Academic literature on the topic 'PBAC'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'PBAC.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "PBAC"
1
Marshall, Richard S., David C. Gemperline, Fionn McLoughlin, Adam J. Book, Kay Hofmann, and Richard D. Vierstra. "An evolutionarily distinct chaperone promotes 20S proteasome α-ring assembly in plants." Journal of Cell Science 133, no. 21 (October 8, 2020): jcs249862. http://dx.doi.org/10.1242/jcs.249862.
Full textAbstract:
ABSTRACTThe core protease (CP) subcomplex of the 26S proteasome houses the proteolytic active sites and assumes a barrel shape comprised of four co-axially stacked heptameric rings formed by structurally related α- and β-subunits. CP biogenesis typically begins with the assembly of the α-ring, which then provides a template for β-subunit integration. In eukaryotes, α-ring assembly is partially mediated by two hetero-dimeric chaperones, termed Pba1–Pba2 (Add66) and Pba3–Pba4 (also known as Irc25–Poc4) in yeast. Pba1–Pba2 initially promotes orderly recruitment of the α-subunits through interactions between their C-terminal HbYX or HbF motifs and pockets at the α5–α6 and α6–α7 interfaces. Here, we identified PBAC5 as a fifth α-ring assembly chaperone in Arabidopsis that directly binds the Pba1 homolog PBAC1 to form a trimeric PBAC5–PBAC1–PBAC2 complex. PBAC5 harbors a HbYX motif that docks with a pocket between the α4 and α5 subunits during α-ring construction. Arabidopsis lacking PBAC5, PBAC1 and/or PBAC2 are hypersensitive to proteotoxic, salt and osmotic stresses, and display proteasome assembly defects. Remarkably, whereas PBAC5 is evolutionarily conserved among plants, sequence relatives are also dispersed within other kingdoms, including a scattered array of fungal, metazoan and oomycete species.
2
Porrata, Luis F., Dennis A. Gastineau, Alvaro Pineda, Jeffrey L. Winters, S. Breanndan Moore, Douglas J. Padley, Kevin L. Bundy, et al. "Increasing the Number of Apheresis Collections Increases Lymphocyte Collection and Affects Survival after Autologous Stem Cell Transplantation for Non-Hodgkin Lymphoma." Blood 104, no. 11 (November 16, 2004): 892. http://dx.doi.org/10.1182/blood.v104.11.892.892.
Full textAbstract:
Abstract Peripheral blood infused total autograft absolute lymphocyte count (A-ALC) correlates with day 15 absolute lymphocyte count and is an independent prognostic factor for survival after autologous stem cell transplantation (ASCT) for non-Hodgkin lymphoma (NHL). Factors to enhance A-ALC collections are not well defined. We hypothesize that the number of peripheral blood apheresis collections (PBAC) directly correlates with A-ALC. 190 consecutive NHL patients who underwent ASCT at the Mayo Clinic between 1993 and 2001 were analyzed. The primary end point of the study was to assess the correlation between the number of PBAC and A-ALC. The secondary end point was to determine if the number of PBAC affected survival post-ASCT. Of the 190 patients, 18 patients underwent 1 PBAC, 23 patients 2 PBAC, 50 patients 3 PBAC, 37 patients 4 PBAC, 50 patients 5 PBAC, and 12 patients had ≥ 6 PBAC. There was no association between the number of PBAC and the number of CD34+ stem cells collected (p= 0.25). A strong association between number of PBAC and A-ALC (Kruskall Wallis test, p <0.0001)(Figure 1) was identified. Using a cut-off of 4 PBAC, superior overall survival (OS) and progression-free survival (PFS) were observed for patients that underwent 4 PBAC or more compared to patients that underwent less than 4 PBAC (86 months vs 18 months, p <0.0001; 76 months vs 10 months, p <0.0001, respectively). Multivariate analysis demonstrated PBAC ≥ 4 is an independent prognostic factor for OS (RR = 0.654, 95%CI: 0.529–0.804, p< 0.0001) and for PFS (RR = 0.682, 95%CI: 0.561–0.826, p< 0.0001) when compared with other significant factors including performance status, lactate dehydrogenase and extra nodal disease. These data suggest that increasing the number of PBAC beyond the minimum number required to meet CD34+ collection targets may result in improved overall and progression-free survival mediated by an increase in autograft absolute lymphocyte count.
3
El-khadragy, Manal, Wafa A. Al-Megrin, Norah A. AlSadhan, Dina M. Metwally, Rehab E. El-Hennamy, Fatma Elzahraa H. Salem, Rami B. Kassab, and Ahmed E. Abdel Moneim. "Impact of Coenzyme Q10 Administration on Lead Acetate-Induced Testicular Damage in Rats." Oxidative Medicine and Cellular Longevity 2020 (June 3, 2020): 1–12. http://dx.doi.org/10.1155/2020/4981386.
Full textAbstract:
Exposure to lead (Pb) causes multiorgan dysfunction including reproductive impairments. Here, we examined the protective effects of coenzyme Q10 (CoQ10) administration on testicular injury induced by lead acetate (PbAc) exposure in rats. This study employed four experimental groups (n=7) that underwent seven days of treatment as follows: control group intraperitoneally (i.p.) treated with 0.1 ml of 0.9% NaCl containing 1% Tween 80 (v:v), CoQ10 group that was i.p. injected with 10 mg/kg CoQ10, PbAc group that was i.p. treated with PbAc (20 mg/kg), and PbAc+CoQ10 group that was i.p. injected with CoQ10 2 h after PbAc. PbAc injection resulted in increasing residual Pb levels in the testis and reducing testosterone, luteinizing hormone, and follicle-stimulating hormone levels. Additionally, PbAc exposure resulted in significant oxidative damage to the tissues on the testes. PbAc raised the levels of prooxidants (malondialdehyde and nitric oxide) and reduced the amount of endogenous antioxidative proteins (glutathione and its derivative enzymes, catalase, and superoxide dismutase) available in the cell. Moreover, PbAc induced the inflammatory response as evidenced by the upregulation of inflammatory mediators (tumor necrosis factor-alpha and interleukin-1 beta). Further, PbAc treatment induced apoptosis in the testicular cells, as indicated by an increase in Bax and caspase 3 expression, and reduced Bcl2 expression. CoQ10 supplementation improved testicular function by inhibiting Pb accumulation, oxidative stress, inflammation, cell death, and histopathological changes following PbAc exposure. Our findings suggest that CoQ10 can act as a natural therapeutic agent to protect against the reproductive impairments associated with PbAc exposure.
4
Lybrand, Sean, and Michael Wonder. "Analysis of PBAC submissions and outcomes for medicines (2010–2018)." International Journal of Technology Assessment in Health Care 36, no. 3 (June 2020): 224–31. http://dx.doi.org/10.1017/s026646232000029x.
Full textAbstract:
ObjectivesThe Pharmaceutical Benefits Scheme (PBS) provides timely, reliable, and affordable access to necessary medicines for Australians. We reviewed the Pharmaceutical Benefits Advisory Committee (PBAC) submissions and their related outcomes and timelines since 2010.MethodsWe examined the PBS Website to identify submissions and their related PBAC outcomes for new medicines, new indications, and new combination products that had been considered by the PBAC since 2010.ResultsThirty-five PBAC meetings were held during the study period, at which the Committee considered 781 submissions (1,074 medicine/patient population pairings). We saw an increase in the annual number of submissions (medicine/patient population parings). The recommendation rate for the study period was higher than the rejection rate. The annual mean value for the period from the date of initial PBAC recommendation to the date of PBS listing ranged from 357 to 644 days; the annual mean value for the period of the date of PBAC recommendation to the date of PBS listing ranged from 187 to 245 days. It took, on average, 1.70 submissions that included an economic evaluation to obtain a PBAC recommendation. It took more submissions to obtain a PBAC recommendation for a cost-effectiveness analysis submission than it did for a CMA submission. The PBAC was willing to recommend medicines for most acceptable base-case incremental cost-effectiveness ratio (ICER) bands, and the majority of the PBAC did not recommended any medicine in the study period that had a base-case ICER >AUD75,000.ConclusionsThe results of our analyses reveal a minor reduction in the period from the date of PBAC recommendation to the date of PBS listing. Several analyses were hampered by a high proportion of missing data.
5
S. Yousef, Al Omar, Alkhuriji A. Fahad, Ahmed E. Abdel Moneim, Dina M. Metwally, Manal F. El-khadragy, and Rami B. Kassab. "The Neuroprotective Role of Coenzyme Q10 Against Lead Acetate-Induced Neurotoxicity Is Mediated by Antioxidant, Anti-Inflammatory and Anti-Apoptotic Activities." International Journal of Environmental Research and Public Health 16, no. 16 (August 13, 2019): 2895. http://dx.doi.org/10.3390/ijerph16162895.
Full textAbstract:
Heavy metal exposure, in lead (Pb) particularly, is associated with severe neuronal impairment though oxidative stress mediated by reactive oxygen species, and antioxidants may be used to abolish these adverse effects. This study investigated the potential neuroprotective role of coenzyme Q10 (CoQ10) against lead acetate (PbAc)-induced neurotoxicity. Twenty-eight male Wistar albino rats were divided into four equal groups (n = 7) and treated as follows: the control group was injected with physiological saline (0.9% NaCl); the CoQ10 group was injected with CoQ10 (10 mg/kg); PbAc group was injected with PbAc (20 mg/kg); PbAc + CoQ10 group was injected first with PbAc, and after 1 h with CoQ10. All groups were injected intraperitoneally for seven days. PbAc significantly increased cortical lipid peroxidation, nitrate/nitrite levels, and inducible nitric oxide synthase expression, and decreased glutathione content, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase activity and mRNA expression, as well as nuclear factor erythroid 2–related factor 2 (Nrf2) and homoxygenase-1 (HO-1) expression. PbAc also promoted the secretion of interleukin-1ß and tumor necrosis factor-α, inhibited interleukin-10 production, triggered the activation of pro-apoptotic proteins, and suppressed anti-apoptotic proteins. Additionally, PbAc increased the cortical levels of serotonin, dopamine, norepinephrine, GABA, and glutamate, and decreased the level of ATP. However, treatment with CoQ10 rescued cortical neurons from PbAc-induced neurotoxicity by restoring the balance between oxidants and antioxidants, activating the Nrf2/HO-1 pathway, suppressing inflammation, inhibiting the apoptotic cascade, and modulating cortical neurotransmission and energy metabolism. Altogether, our findings indicate that CoQ10 has beneficial effects against PbAc-induced neuronal damage through its antioxidant, anti-inflammatory, anti-apoptotic, and neuromodulatory activities.
6
Baty, RS, KE Hassan, KF Alsharif, RE El-Hennamy, EK Elmahallawy, MM Hafez, AE Abdel Moneim, and RB Kassab. "Neuroprotective role of luteolin against lead acetate-induced cortical damage in rats." Human & Experimental Toxicology 39, no. 9 (March 25, 2020): 1200–1212. http://dx.doi.org/10.1177/0960327120913094.
Full textAbstract:
Luteolin (LUT) is a glycosylated flavonoid compound that has multiple beneficial pharmacological and biological impacts. The current investigation was undertaken to evaluate the putative neuroprotective potency of LUT against neuronal damage induced by lead acetate (PbAc). Twenty-eight rats were placed into four equal groups. Group 1: served as the control group, group 2: rats were supplemented orally with LUT (50 mg kg−1), group 3: rats were intraperitoneally injected with PbAc (20 mg kg−1), and group 4: rats were pretreated with LUT before PbAc injection with the same doses. All animals were treated for 7 days. The exposure to PbAc increased the concentration of lead in the cortical tissue, neuronal lipid peroxidation, and nitric oxide (NO) production and decreased the antioxidant enzymes. Additionally, PbAc enhanced a neuroinflammatory response in the cortical tissue through increasing the pro-inflammatory cytokines secretion and inducible NO synthase expression. Moreover, cortical cell death was recorded following PbAc intoxication as evidenced by the enhancement of the proapoptotic and inhibiting the antiapoptotic markers. Interestingly, LUT supplementation reversed the cortical adverse reactions induced by PbAc. Taken together, these findings may suggest that LUT may be useful for attenuating neuronal damage induced by PbAc through inhibiting the oxidative damage, neuroinflammation, and the cortical cell death.
7
Behairy, Amany, Mohamed M. Hashem, Khaled Abo-El-Sooud, Abeer E. El-Metwally, Bayan A. Hassan, and Yasmina M. Abd-Elhakim. "Quercetin Abates Aluminum Trioxide Nanoparticles and Lead Acetate Induced Altered Sperm Quality, Testicular Oxidative Damage, and Sexual Hormones Disruption in Male Rats." Antioxidants 11, no. 11 (October 28, 2022): 2133. http://dx.doi.org/10.3390/antiox11112133.
Full textAbstract:
This study examined the effects of exposure to lead acetate (PbAc) and/or aluminum trioxide nanoparticles (Al2O3NPs) on testicular function. Additionally, the probable reproprotective effects of quercetin (QTN) against Al2O3NPs and PbAc co-exposure in male Sprague Dawely rats were assessed. Al2O3NPs (100 mg/kg b.wt.), PbAc (50 mg/kg b.wt.), and QTN (20 mg/kg b.wt.) were orally administered for 60 days. Then, spermiogram, histopathological examinations of the testis and accessory glands, and immunohistochemical detection of androgen receptors (AR) and tumor necrotic factor alpha (TNF-α) were achieved. Moreover, serum levels of male sex hormones and testicular levels of antioxidant indices were estimated. The results showed that Al2O3NPs and/or PbAc caused significant sperm abnormalities, testicular oxidative stress, and histopathological changes. Furthermore, serum testosterone, LH, and FSH levels significantly decreased, while estradiol levels significantly increased. The Al2O3NPs and/or PbAc co-exposed group had more obvious disturbances. Furthermore, QTN co-administration significantly reversed the Al2O3NPs and PbAc-induced testicular histopathological alterations, reduced antioxidant defenses, and altered AR and TNF-α immune expression in testicular tissues. Conclusively, Al2O3NPs and/or PbAc evoked testicular dysfunction by inducing oxidative injury and inflammation. However, QTN oral dosing effectively mitigated the negative effects of Al2O3NPs and PbAc by suppressing oxidative stress and inflammation and improving the antioxidant defense system.
8
Halimeh, Susan, Hannelore Rott, Guenther Kappert, and Manuela Siebert. "Establishment Of a Reference Range For The Pbac-Score." Blood 122, no. 21 (November 15, 2013): 4772. http://dx.doi.org/10.1182/blood.v122.21.4772.4772.
Full textAbstract:
Introduction Heavy menstrual bleeding (HMB) is defined as bleeding that lasts for more than seven days or as the loss of more than 80mL of blood per mentrual cycle (1)The menstrual blood loss can be quantified by the use of a pictorial bleeding assessment chart (PBAC). The PBAC-Score was initially validated by Higham et al. (2) With the PBAC-Score the women can capture the number of pads or tampons and also state the intensity through the assessment of the drenching. The aim of this study was to establish a reference range for the PBAC-Score. Samples and Methods We analysed samples of 310 women with menorrhagia and 108 controls by conducting the following tests: Blood count, VWF:RCo, VWF:Ag, VWF:CB, VWF:multimers, Fibrinogen (Clauss), activities of FII, FV, FVII, FVIII (clotting and chromogenic), FIX, FX, FXI, FXII, FXIII. In all women the menstrual blood loss was quantified usind the PBAC-Score and the results were compared. Results In 202 of 310 women (65.1%) a bleeding disorder could be detected. In those with a bleeding disorder, the distribution was as followed: 64% of these women had a von Willebrand disease, 7.2% FVII-deficiency, 7.7% FXIII-deficiency and the remaining 21.1% other mild factor dificiencies. The mean PBAC-Score in women with menorrhagia was 262 (range 31 – 4212) in our control group the mean PBAC-Score was 60 (range 8 – 97). Discussion/Conclusion Attemps to measure the quantity of menstrual blood loss can be useful in clinical practice. In our opinion the best cut of for the PBAC-Score is 100 with a sensitifity of 90% and a specifity of 100%. We found a high correlation of a PBAC >100 and an inherited bleeding disorder, especially von Willebrand diesease. In 65.1% of our patients an abnormal coagulation was found. In 4 (3.7%) women of the control group slightly abnormal von Willebrand parameters could been dectected. We validated the reference range for the PBAC-Score as 0 - 100. Disclosures: Halimeh: Octapharma AG: Investigator Other, Research Funding.
9
AL-Megrin, Wafa A., Afrah F. Alkhuriji, Al Omar S. Yousef, Dina M. Metwally, Ola A. Habotta, Rami B. Kassab, Ahmed E. Abdel Moneim, and Manal F. El-Khadragy. "Antagonistic Efficacy of Luteolin against Lead Acetate Exposure-Associated with Hepatotoxicity is Mediated via Antioxidant, Anti-Inflammatory, and Anti-Apoptotic Activities." Antioxidants 9, no. 1 (December 21, 2019): 10. http://dx.doi.org/10.3390/antiox9010010.
Full textAbstract:
The abundant use of lead (Pb; toxic heavy metal) worldwide has increased occupational and ecosystem exposure, with subsequent negative health effects. The flavonoid luteolin (LUT) found in many natural foodstuffs possesses antioxidant and anti-inflammatory properties. Herein, we hypothesized that LUT could mitigate liver damage induced by exposure to lead acetate (PbAc). Male Wistar rats were allocated to four groups: control group received normal saline, LUT-treated group (50 mg/kg, oral, daily), PbAc-treated group (20 mg/kg, i.p., daily), and LUT+PbAc-treated group (received the aforementioned doses via the respective routes of administration); the rats were treated for 7 days. The results revealed that PbAc exposure significantly increased hepatic Pb residue and serum activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin value. Oxidative reactions were observed in the liver tissue following PbAc intoxication, characterized by the depletion and downregulation of antioxidant proteins (glutathione, glutathione reductase, glutathione peroxidase, superoxide dismutase, catalase, nuclear factor erythroid 2-related factor 2, and heme oxygenase-1), and an increase in oxidants (malondialdehyde and nitric oxide). Additionally, PbAc increased the release and expression of the pro-inflammatory cytokines (tumor necrosis factor alpha and interleukin-1 beta), inducible nitric oxide synthase, and nuclear factor kappa B. Moreover, PbAc enhanced hepatocyte loss by increasing the expression of pro-apoptotic proteins (Bax and caspase-3) and downregulating the anti-apoptotic protein (Bcl-2). The changes in the aforementioned parameters were further confirmed by noticeable histopathological lesions. LUT supplementation significantly reversed all of the tested parameters in comparison with the PbAc-exposed group. In conclusion, our findings describe the potential mechanisms involved in the alleviation of PbAc-induced liver injury by luteolin via its potent anti-inflammatory, antioxidant, and anti-apoptotic properties.
10
Flowers, Melinda, Sean Lybrand, and Michael Wonder. "Analysis of sponsor hearings on health technology assessment decision making." Australian Health Review 44, no. 2 (2020): 258. http://dx.doi.org/10.1071/ah18113.
Full textAbstract:
Objective The aim of this study was to get a better understanding of the frequency of Pharmaceutical Benefits Advisory Committee (PBAC) hearings, the factors that influence a sponsor’s decision to proceed with a hearing and to assess the impact hearings may have had on PBAC decision making. Methods All public summary documents (PSDs) from March 2014 to November 2016 PBAC meetings, obtained from the Pharmaceutical Benefits Scheme (PBS) website, were examined to identify major submissions for which sponsor hearings were conducted. Each PSD was analysed to determine the topics discussed at the sponsor hearing and the ‘usefulness’ of a sponsor hearing from the PBAC’s perspective. Results During the study period there were 472 PSDs. 74 sponsor hearings (28% of major submissions) were conducted during the study period. A clinician external to the sponsor presented at the majority of the hearings (78%) and accordingly, the main topics presented related to clinical positioning/use and clinical benefit/use. Conclusion The PBAC considered approximately 45% of sponsor hearings to be informative or moderately informative whereas 18% were classed as uninformative. What is known about the topic? Although the sponsors of medicines being considered by the Pharmaceutical Benefits Advisory Committee (PBAC) for public subsidy have been able to give a 10 min presentation to the Committee at the time of decision making for several years, it is unknown whether these hearings are beneficial. What does this paper add? We present what is believed to be the results of the first analysis of PBAC sponsor hearings. What are the implications for practitioners? All stakeholders should consider the findings of our research and associated recommendations to ensure that future sponsor hearings enhance PBAC decision making and promote good public health policy.
Dissertations / Theses on the topic "PBAC"
1
Pereira, Danilo Assis. "Adaptação e evidências de validade do teste neuropsicológico PBAC para a população brasileira." reponame:Repositório Institucional da UnB, 2014. http://repositorio.unb.br/handle/10482/17166.
Full textAbstract:
Tese (doutorado)—Universidade de Brasília, Faculdade de Ciências da Saúde, Programa de Pós-Graduação em Ciências da Saúde, 2014.Submitted by Ana Cristina Barbosa da Silva (annabds@hotmail.com) on 2014-12-01T16:57:40Z No. of bitstreams: 1 2014_DaniloAssisPereira.pdf: 4139179 bytes, checksum: e48669ba2bd83b61e0a1e8f2e52a7544 (MD5)
Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2014-12-01T18:59:28Z (GMT) No. of bitstreams: 1 2014_DaniloAssisPereira.pdf: 4139179 bytes, checksum: e48669ba2bd83b61e0a1e8f2e52a7544 (MD5)
Made available in DSpace on 2014-12-01T18:59:28Z (GMT). No. of bitstreams: 1 2014_DaniloAssisPereira.pdf: 4139179 bytes, checksum: e48669ba2bd83b61e0a1e8f2e52a7544 (MD5)
Instrumentos de rastreio cognitivos são utilizados em todo o mundo por vários profissionais de saúde para detectar indivíduos com provável comprometimento cognitivo. O teste PBAC(Philadelphia Brief Assessment of Cognition) foi proposto a partir de uma série de instrumentos neuropsicológicos bem estabelecidos na literatura para avaliar comportamento social, memória,linguagem, percepção visoespacial e funções executivas. A literatura aponta que os subtestes do PBAC são correlacionados com perda de massa encefálica em pacientes com doenças neurodegenerativas. Este estudo tem como objetivo verificar evidências de validade da adaptação brasileira do teste de rastreio cognitivo PBAC usando amostras clínicas e populacionais, comparando-o a outros testes de rastreio cognitivo e funcionais. Participaram deste estudo 325 voluntários entre 18 e 94 anos de idade (mediana de 65), com escolaridade entre 0 e 19 anos (mediana de 13). Quatro amostras distintas foram utilizadas: 103 jovens universitários, 183 idosos hígidos, 24 pacientes portadores de demências (sendo mais comum a doença de Alzheimer) e 16 Kalungas moradores da região de Cavalcante-GO, descendentes dos quilombolas. Outros instrumentos de rastreio cognitivo (MEEM, Teste do Relógio, Trilhas A e B,Stroop) e funcionais (GDS e Pfeffer) foram utilizados numa sub amostra para a validação convergente e discriminante. Análises especiais de modelagem de equação estrutural Bayesiana(BSEM) e teoria de resposta ao item multidimensionais (TRIm) e multigrupo foram utilizadas. O teste PBAC possui boa confiabilidade na amostra geral (alfa = 0,86), mas não na amostra de jovens (0,37). Quatro dimensões distintas foram encontradas: memória, linguagem, habilidade visoconstrutiva e funções executivas. O modelo BSEM mostrou para o grupo de idosos hígidos que a idade influencia negativamente a memória, mas não as demais habilidades. A escolaridade apresentou influência positiva em todos os constructos latentes. Com exceção dos itens Escrita e Trilhas, todos os demais apresentaram maior informação nas habilidades latentes dos idosos com demência, quando comparados aos hígidos nas funções de informações da TRI multigrupo.Tabelas normativas com a habilidade (teta), escore z e escala T foram calculadas para cada dimensão do teste, tendo como norma os dados dos idosos hígidos. O teste de rastreio cognitivo PBAC se mostrou tão sensível e específico quanto o MEEM para a detecção de demência do tipo Alzheimer. O teste é mais informativo em pessoas com habilidades latentes mais baixas. A retirada de alguns itens do teste pode aumentar sua acurácia para o diagnóstico de Alzheimer,no entanto mais estudos com outros grupos clínicos se tornam essenciais, uma vez que sua construção objetivou a avaliação multiclínica. ________________________________________________________________________________ ABSTRACT
Cognitive screening tests are used worldwide by many health professionals to detect individuals with probable cognitive impairment. The PBAC (Philadelphia Brief Assessment of Cognition) was proposed based on a series of well-established neuropsychological instruments to assess socialbehavior/comportment, memory, language, visuospatial perception, and executive functions. The literature indicates that the subtests of the PBAC are correlated with loss of brain tissue in patients with several neurodegenerative diseases. This study aims to find evidence of validation of the PBAC using clinical and population samples, and comparing it to other cognitive and functional screening tests. Participated in this study 325 individuals aged between 18 and 94 years-old(median 65), and schooling between 0 and 19 years (median 13). Four different samples were used: 103 university students, 183 healthy elderly, 24 patients with dementia (most common being Alzheimer's disease), and 16 afro-descendants (called Kalungas, living at Cavalcante-GO). All participants signed a consent form. Other cognitive screening instruments (MMSE, Clock Design Test, Trail Tests A and B, and Victoria Stroop Test) and functional tests (Pfeffer and GDS) were used in a subsample for the convergent and discriminant validity. Special analysis of Bayesianstructural equation modeling (BSEM), multi-group and multidimensional response theory item(mIRT) were used. The PBAC test showed good reliability in the overall sample (alpha = 0.86),but not in the youth sample (0.37). Four distinct dimensions were found: memory, language,executive functions, and visuos patial perception. The BSEM model showed that in healthy elderly people, age negatively influences memory, but not other skills. Education had a positive influence on all latent constructs. Except Writing and Oral Trails, all other items presented greaterinformation on the latent abilities for the clinical group when compared to the information functions of the healthy elderly group. Normative tables with the ability (theta), z scale, and T scores were calculated for each dimension of the test, using the healthy elderly normative data. The PBAC cognitive screening test proved to be as sensitive and specific as the MMSE for detecting cognitive disorders associated to Alzheimer’s dementia. The test is more informative on those individuals with lower latent abilities. The withdrawal of some items can increase PBAC’saccuracy for the diagnosis of Alzheimer's, however further studies with other clinical groups are essential since its construction aimed to evaluate other kind of neurodegenerative disease.
2
CALO', LUCIA. "ANALISI DEI PROBLEMI GINECOLOGICI ED OSTETRICI NELLE DONNE CON COAGULOPATIA A DIATESI EMORRAGICA ATTRAVERSO IL REGISTRO INTERNAZIONALE (WRBDD)." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/170490.
Full textAbstract:
SUMMARY
Patients affected by bleeding disorders present a wide spectrum of clinical symptoms that vary from mild or moderate bleeding tendency to significant episodes. Women with inherited bleeding disorders are particularly disadvantaged since in addition to suffering from general bleeding symptoms they are also at risk of bleeding complications from regular haemostatic challenges during menstruation, pregnancy and childbirth. Moreover, such disorders pose important problems for affected women due to their reduced quality of life caused by limitations in activities and work, and alteration of their reproductive life. These latter problems include excessive menstrual bleeding or menorrhagia, miscarriage, bleeding complications during pregnancy and after delivery and their related complications such as acute or chronic anaemia.
Moreover, reliable information on clinical management are scarce, only a few available long term prospective studies of large cohorts provide evidence-based guideline about diagnosis and treatment.
To this end, the University of Milan has created a working group on menorrhagia and other gynecological problems in women with rare bleeding disorders (WRBD: http://www.wrbd.org/network.htm) involving worldwide renewed centers besides the Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre of Milan. A prospective study recruiting women with confirmed diagnosis of von Willebrand disease (VWD), rare coagulation disorders (RBDs: rare bleeding disorders) and platelet disorders was designed. Women without evidence of coagulation disorders constituted the control group.
The aim of this project was to retrospectively and prospectively collect a large cohort of women to:
- evaluate the prevalence of gynaecological problems (menarche, ovulation bleeding, menorrhagia, bleeding during pregnancy and postpartum bleeding)
- evaluate the association between menstrual loss and clinical severity (other bleeding symptoms)
- evaluate the association between clinical severity and phenotype results
- to collect and analyse data on concomitant gynaecological abnormalities, complications of menorrhagia (anaemia), requirement of gynaecological intervention and to evaluate the occurrence of abortion, miscarriage and other pregnancy complications.
A specifically tailored questionnaire was used to collect data, along with the Bleeding Score (BS) quesstionnaire, capable of translating the hemorrhagic history of the subject in a numerical coefficient, and the pictorial blood assessment chart (PBAC), graphical tool that scores the intensity of menstrual flow, thus defining the severity of menorrhagia. The collected data have been then entered into a database specifically created to obtain a complete and extensive amount of information which will ultimately be able to extrapolate the clinical information necessary for the intended purposes.
After the first year, 231 patients were enrolled in the study: 113 (48.9%) patients were affected with VWD, 38 (16.5%) with RBDs and 80 (34%) were controls for a total of 214 pregnancies.
Our data showed that menorrhagia was a specific symptom of women with VWD, while the profuse menarche and intermittent and heavy menstrual bleeding seemed to be a symptom of women with RBDs. However, the intra-abdominal bleeding and the vaginal bleeding near ovulation seem not to be specifically related to the presence of hemorrhagic disease, confirming currently available data from the literature. Similarly, hemorrhagic complications during surgery do not seem to have a higher incidence in the presence of VWD or RBDs compared with controls, but we consider that these data needs to be further analyzed after further enlargement of the sample size in order to discriminate the population in two groups: with and without prophylaxis preopaeratoria.
The results of the study did not detect significant differences between the two groups (women with VWD and RDBs) and the general population with regard to the rate of spontaneous abortions, intrauterine deaths and the incidence of bleeding occurring during pregnancy, confirming the data of the current literature. Hemorrhage after vaginal delivery was, however, the only hemorrhagic complication showing a significantly higher incidence in the two groups of patients compared with controls. In particular secondary postpartum haemorrhage was higher in women with VWD compared to controls.
BS and PBAC in our study were also tested for their potential for predicting the phenomenon of bleeding the patient. The PBAC showed to have a predictive value on the profuse menarche in the group of women with RBDs (threshold value 606.5) and acute hemorrhagic event and bleeding near ovulation in women with VWD (threshold value 737 and 682.5, respectively). Both scoring systems were found to predict the postpartum bleeding in women with VWD: a BS higher than 11 seemed to be associated to a 3-fold increased risk of postpartum bleeding, whereas a PBAC higher than 200 to a 18-fold increased risk.
The coagulant activity level of the deficient factor was shown to be a predictive tool for hemorrhagic event at menarche and for the acute bleeding in women with VWD (24.5 and 17.5, respectively; threshold value 22) and for the acute bleeding in women with RBDs (threshold 27). It was also shown to be associated to postpartum hemorrhage in women with VWD (an activity level less than 23% was associated to a to 6-fold higher risk).
In conclusion, our results, although preliminary have considerable importance as an outcome of a collaborating data collection project, using an ad hoc database, whose final validation will happen in the course of study with the ultimate goal of providing all the necessary features to make it maximally effective and accurate. Eventually, the analysis of data collected will provide a suitable substrate for the drafting of guidelines for the universal prophylactic and therapeutic approach to obstetricians hemorrhagic gynecological problems.
3
Silva, Rafael Soares. "Termo-estabilização da blenda PLA/PBAT." Universidade Presbiteriana Mackenzie, 2016. http://tede.mackenzie.br/jspui/handle/tede/2854.
Full textAbstract:
Submitted by Rosa Assis (rosa_assis@yahoo.com.br) on 2016-09-22T13:50:32Z
No. of bitstreams: 2
license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)
Rafael Soares Silva.pdf: 2923341 bytes, checksum: a831738a4d83ca6103e1489945754a7b (MD5)Made available in DSpace on 2016-09-22T13:50:32Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Rafael Soares Silva.pdf: 2923341 bytes, checksum: a831738a4d83ca6103e1489945754a7b (MD5) Previous issue date: 2016-05-20
This study aimed to evaluate the effects of additives (primary and secondary antioxidants) in thermal stabilization process of poly (lactic acid) / poly (butylene adipate-co-terephthalate) - PLA / PBAT using a torque rheometer as a preliminary tool evaluation of the stabilization process. The additives Irganox 1010, Irganox 1076, Irganox B900, Irgafos 168, and a flavonoid were used in two concentrations, 0.3 and 0.5% w/w. The assessment of the effects of stabilizing additives was carried out by monitoring the torque during mixing molar mass measurements, infrared analysis, turbidity and Scanning Electron Microscopy of the samples after processing. It carried out the monitoring of the pure blend torque values and addition of stabilizing additives during processing up to 5 minutes in an internal mixer of the type "mixer" under rotation of 60 rpm and a temperature of 180 °C. Within a series of primary and secondary antioxidants, it was found that some of these additives failed torque values greater than or similar to the pure blend at certain concentrations (Irganox 1076, Irganox B900 and Irgafos 168). molar mass measurements showed that pure processed blend undergoes a large number of chain scission and most additives stabilizing action achieved unless the flavonoid. One important information obtained through analyzes of torque rheometry and molar mass that is higher drying time strongly prevents hydrolysis reactions. Comparing the infrared spectra of pure and pure blend blend processed, there is not the appearance of no new peak occurs due to the degradative process. By UV-Vis analysis of the polymer solutions we verified the presence of crosslinked polymer microstructures due to thermo-oxidative reactions. Images obtained by scanning Elletrônica Microscopy (SEM), one can observe the presence of two distinct phases for the pure blend processed, and the use of additives in both compositions show a much smaller difference of phases to blend pure. These results indicate the possibility of using commercial additives used for non-biodegradable polymers in systems using biodegradable polymers.
Este trabalho teve como objetivo avaliar a ação de aditivos (antioxidantes primários e secundários) no processo de estabilização térmica da blenda poli(ácido láctico)/poli(butileno adipato-co-tereftalato) - PLA/PBAT usando um reômetro de torque como ferramenta prévia de avaliação do processo de estabilização. Os aditivos Irganox 1010, Irganox 1076, Irganox B900, Irgafos 168 e o Flavonóide foram usados em duas concentrações, 0,3 e 0,5% em massa. A avaliação dos efeitos dos aditivos estabilizantes foi realizada por meio de monitoramento do torque durante mistura, medidas de massa molar, análises de infravermelho, turbidez e microscopia eletrônica de varredura das amostras após processamento. Realizou-se o monitoramento dos valores de torque da blenda pura e com adição de aditivos estabilizantes durante processamento por até 5 minutos em um misturador interno do tipo “Mixer” sob rotação de 60 rpm e temperatura de 180 oC. Dentro de uma série de antioxidantes primários e secundários, verificou-se o uso de alguns desses aditivos conseguiram valores de torque superior ou semelhante ao da blenda pura em determinadas concentrações (Irganox 1076, Irganox B900 e Irgafos 168). Medidas de massa molar mostraram que a blenda pura processada sofre um grande número de cisão de cadeias e que a maioria dos aditivos conseguiram ação estabilizante menos o flavonóide. Uma informação importante obtida por meio das análises de reometria de torque e massa molar é que um tempo maior de secagem evita fortemente as reações de hidrólise. Comparando-se os espectros de infravermelho da blenda pura e da blenda pura processada, nota-se que não aparecem nenhum novos picos relacionados ao processo degradativo. Através da análise de UV-Vis das soluções poliméricas verificou-se a presença de microestruturas poliméricas reticuladas em virtude das reações termo-oxidativas. Imagens obtidas por Microscopia Elletrônica de varredura (MEV), evidenciam a presença de duas fases distintas para a blenda pura processada, e o uso dos aditivos nas duas composições mostram uma diferenciação das fases muito menor que para blenda pura. Esses resultados indicam que existe a possibilidade do uso de aditivos comerciais usados para polímeros não-biodegradáveis em sistemas com polímeros biodegradáveis.
4
Fu, Yang. "Morphologie des mélanges ternaires PLA/PBAT/PA." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEM068/document.
Full textAbstract:
Ce travail vise à obtenir une morphologie cœur-peau directement lors du mélangeage à l’état fondu de polymères ternaires PLA/PBAT/PA. Le but final est d'améliorer la ténacité de l'acide polylactique (PLA). La morphologie des mélanges de polymères multi-phases est contrôlée par la thermodynamique du système. La morphologie des mélanges ternaires peut être prédite à partir des valeurs relatives des trois coefficients d'étalement caractérisant le triplet de polymères. Les coefficients d'étalement sont calculés à partir des valeurs des tensions interfaciales entre les composants binaires. La détermination des tensions interfaciales entre PLA, poly (butylène adipate-co-téréphtalate) (PBAT) et un copolyamide (PA) prédit une morphologie dispersée complexe dans la matrice PLA où les sous-inclusions PA sont partiellement encapsulées dans la phase PBAT. Cette morphologie a été obtenue par mélange à l'état fondu des trois composants, comme observé par les observations en microscopie électronique à balayage. Dans une seconde étape, une compatibilisation sélective a été utilisée pour modifier l'emplacement des sous-inclusions de PA. A cette fin, deux copolymères diblocs PBAT-b-PLA, PA-b-PBAT ont été synthétisés. La présence des copolymères diblocs nous permet de modifier la tension interfaciale des couples PLA/PBAT, PA/PBAT. Cette modification de l'équilibre de tension interfaciale modifie avec succès la morphologie, passant d’une semi-encapsulation à une encapsulation complète des sous-inclusions de PA dans les gouttes de PBAT. La performance mécanique de ce mélange ternaire a été évaluéeThis work aims at achieving direct core-shell morphologies in ternary PLA/PBAT/PA polymer blends by melt mixing. The final goal is to improve the toughness of polylactic acid (PLA). The morphology of multi-phase polymer blends is controlled by the thermodynamics of the system. The morphology of ternary blends can be predicted from the relative values of the three spreading coefficients characterizing the triplet of polymers. Spreading coefficients are calculated from the values of interfacial tensions between binary components. The determination of interfacial tensions between a PLA, a poly(butylene adipate-co-terephthalate) (PBAT) and a copolyamide (PA) predicts a complex dispersed morphology in the PLA matrix where PA subinclusions are partly encapsulated in the PBAT phase. This morphology was obtained by melt mixing the three components, as observed by scanning electron microscopy. In a second step, selective compatibilization was used to modify the PA sub-inclusion location. To this end, PBAT-b-PLA and PA-b-PBAT di-block copolymers were synthesized. The presence of the di-block copolymers enabled to modify the interfacial tension in PLA/PBAT and PA/PBAT. The modification of the interfacial tension balance was shown to successfully change the morphology from semi-encapsulation to full encapsulation of PA sub-inclusions in the PBAT drops. The mechanical performance of this ternary blend was evaluated
5
Vaccioli, Kleber. "Estudo da blenda PBAT/PLA com cargas." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-12072016-101827/.
Full textAbstract:
Neste trabalho compósitos foram obtidos a partir da blenda comercial 100% biodegradável Ecovio® C2224 da BASF, uma blenda formada por 55% em massa de um copoliéster biodegradável, o Ecoflex® (poli[(adipato de butileno)-co-(tereftalato de butileno)]) e 45% em massa de PLA poli(ácido láctico). Como carga, utilizaram-se dois tipos de argilas comerciais do grupo das esmectitas, ambas predominantemente montmorilonitas: Cloisite Sódica® e Cloisite 30B®. Também foi utilizado como carga a sílica coloidal comercial Aerosil 200®, com área superficial de 200 m2/g e diâmetro médio de partícula 12nm. Os compósitos estudados, ambos contendo 5% e 10% em massa de cargas, foram preparados em uma extrusora de rosca dupla, acoplada a um reômetro de torque. O estudo foi dividido em três etapas: 1ª) etapa: Obtenção e caracterização dos compósitos de Ecovio®/ argila e Ecovio® / sílica; 2ª) etapa: Avaliação da fotodegradação do Ecovio® puro e dos compósitos obtidos; 3ª) etapa: Avaliação da biodegradabilidade do Ecovio® puro e dos compósitos após exposição em câmara de UV. As propriedades mecânicas dos compósitos antes e depois de serem submetidos à exposição em câmara de UV foram avaliadas por ensaios de resistência à tração e resistência ao impacto Izod. Os resultados obtidos na 1ª etapa deste trabalho indicaram aumento nos valores de módulo de elasticidade de todos os compósitos, em relação à blenda pura. Destacam-se as composições com 5% e 10% em massa de sílica coloidal, que apresentaram aumentos de até 115% nos valores de módulo de elasticidade, sem perdas significativas em resistência à tração, alongamento e resistência ao impacto, quando comparadas à fase matriz. Na 2ª etapa, a partir de 20 dias de exposição, todas as composições (blendas e compósitos) apresentam redução nas propriedades mecânicas em função do aumento do tempo de exposição à radiação UV. Na 3ª etapa, independente do tipo ou teor de carga presente na blenda, todas as composições apresentaram índices de biodegradabilidade, depois de 120 dias, de 40 a 60%, devido à prévia exposição à radiação UV.In this work, composites were prepared with 100% biodegradable commercial blend Ecovio® C2224 BASF, a polymer blend composed of 55 wt% of a biodegradable copolyester, the Ecoflex®, poly [(butylene adipate) -co- (butylene terephthalate)], and 45 wt% of PLA poly(lactic acid). Two types of commercial clays of the smectite group, predominantly montmorillonites, were used as fillers: Cloisite Na+® and Cloisite 30B®. The commercial colloidal silica Aerosil 200®, with a surface area of 200 m2/g and an average particle diameter of 12 nm, was also used as filler. The composites containing 5 and 10 wt% of filler were obtained in a twin screw extruder coupled to a torque rheometer. This study was divided in three steps: 1st) Preparation and characterization of Ecovio®/clay and Ecovio®/silica composites; 2nd) Evaluation of the photodegradation of pure Ecovio® and of the composites; 3rd) Biodegradability assessment of pure Ecovio® and composites after exposure to UV chamber. The mechanical properties of the composites before and after the exposition to UV were evaluated by tensile and Izod impact strength. The results obtained in the 1st step showed an increase in the tensile modulus of all blends, especially for the compositions with 5 and 10 wt% of colloidal silica, which presented an increase of 115% in their tensile modulus values without significant reduction in impact and tensile strength and elongation, when compared to the pure blend. In the 2nd step, from 20 UV exposure days, all compositions (blends and composites), presented a significant reduction in the mechanical properties as a function of the increase of the UV radiation exposure time. In step 3, regardless of the filler type or content, all blend compositions showed biodegradability index, after 120 days, of 40 to 60%, due to the prior UV exposure.
6
Khan, Anastassiya. "Synthesis and characterization of defective PBAs electrode material." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21015/.
Full textAbstract:
Sodium manganese hexacyanoferrate (NaMnHCF) and its derivatives have been synthesized by simple co-precipitation method with addition of the citric and ascorbic acids respectively. The correspondent crystal structure, water content, chemical formula and a deep structural investigation of prepared samples have been performed by means of the combination of the laboratory and synchrotron techniques (PXRD, FT-IR, TGA, MP-AES and XAS). Electrochemical tests have been done using three-electrode system in sodium nitrate solution at different concentration. From cyclic voltammetry curves, Fe3+/2+ redox peak has been observed, whereas Mn3+/2+ peak was not always evident. Structural stability of the cycled samples has then been tested using 2D XRF imaging and Transmission X-ray microscopy (TXM) techniques. The intercalation of NaMnHCF after 20 cycles has been found by micro-XANES analysis of the highlighted spots which have been found in the XRF images. TXM has also confirmed the appearance of the intercalated particles after 50 cycles comparing the spectra between charged and discharged materials at three different edges (Mn, Fe and N). However, by comparison with lithium samples, it seems obvious that sodium samples are more homogeneous and intercalation is at the very beginning indicating the relative structural stability of sodium manganese hexacyanoferrate electrode material.
7
Bøe, Andreas Gagnat. "Degradation and Stability of PBCA and POCA Nanoparticles." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22417.
Full textAbstract:
Nanoparticles represent promising carriers for controlled drug delivery. In this project threedifferent intruments: Zetasizer, Nanosight and Gas Chromatography, have been used to detect and analyse degradation of monodisperse poly butylcyanoacrylate (PBCA) and polyoctylcyanoacrylate (POCA) nanoparticles with a mean size diameter of 145 and 155 nm,respectively. It was found that the Nanosight and Gas Chromatography are valuable instrumentsfor detecting and analysing degradation, whereas the Zetasizer turned out to giveunreliable results because of increasing polydispersity in the samples. PBCA and POCAparticles were tested in two different setups. One including a dialysis setup in room temperature,in which the solvent was regularly exchanged. The other consisted of reagent bottlesheld in an oven at 37C. In the dialysis method the influence of buffers with pH 4.0, pH5.5 and pH 7.4 were tested. In the reagent bottles different mediums were tested, like cellmedium, blood serum and buffer pH 7.4 with and without the enzyme esterase. From theseexperiments it became clear that PBCA particles degraded significantly faster than POCAparticles in all tested mediums. Degradation of PBCA particles were also strongly affectedby the pH. At pH 4.0 there was little (10%) or no degradation still after 30 days. The concentration of PBCA particles in pH 7.4 decayed as a 1/x -function, in which 53\% of the PBCA particles in buffer pH 7.4 have been degraded after 8.5 hours.The degradation-rate for PBCA and POCA in blood serum was approximately similar as in buffer pH 7.4, whereas in cell medium it was slightly slower.
8
SOUSA, Jokderlea Correa de. "Estudo da cinética de cristalização do compósito poli(butileno-adipato-co-tereftalato)/fibra de coco." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/17526.
Full textAbstract:
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-07-22T13:49:26Z
No. of bitstreams: 2
license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5)
Dissertação Jokderléa - Versão digital.pdf: 2657401 bytes, checksum: aa4dfc40144fb6bdb5d19dd66aa43470 (MD5)Made available in DSpace on 2016-07-22T13:49:26Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Jokderléa - Versão digital.pdf: 2657401 bytes, checksum: aa4dfc40144fb6bdb5d19dd66aa43470 (MD5) Previous issue date: 2016-02-25
FINEP
ANP
PRH
Neste trabalho estudou-se compósitos poliméricos obtidos a partir de um poliéster biodegradável e fibra de coco (Cocus nucifera), uma fibra abundante na região Nordeste e para a qual não existem relatos na literatura de sua utilização em compósitos com o poli(butileno-adipato-co-tereftalato)(PBAT). O uso de fibra de coco nas formulações é uma alternativa para redução de custos, pois propõe uma substituição parcial do polímero a ser utilizado. Estudou-se a influência da fibra sobre as propriedades reológicas e térmicas dos compósitos. As fibras naturais foram secas e classificadas antes de sua utilização. Foi realizado um teste preliminar por Calorimetria Diferencial Exploratória (DSC) com o PBAT onde foi definida a temperatura de fusão para o processamento no reômetro. Compósitos de PBAT e fibra de coco foram preparados com formulações de 10, 20, 30, 40 e 50% em massa de fibra em um misturador interno. Foi possível quantificar a dependência do torque com a velocidade de rotação dos rotores pelo índice de pseudoplasticidade através da lei da potência. A avaliação reológica dos compósitos obtidos mostrou a dependência do torque e da temperatura com a quantidade de fibra adicionada. Foi realizado um estudo sobre a cristalização dos compósitos com 10, 20 e 30% de fibra comparando com o polímero puro, submetido as mesmas condições de preparação. A análise dos resultados obtidos pelo DSC indicou que a adição de fibras nos compósitos alterou a temperatura de cristalização para valores mais elevados, sugerindo que as fibras podem ter um efeito nucleante. Os compósitos quando submetidos a variações nas velocidades de resfriamento, mostraram que o processo de cristalização se altera, deslocando os picos de cristalização para temperaturas menores, conforme aumentava a velocidade de arrefecimento. Foi construído o modelo cinético de Pseudo-Avrami para o compósito PBAT/10% fibra de coco, pois seus parâmetros de cristalização apresentaram desvios menores ou próximos de 10% em relação ao PBAT puro. Houve boa adequação dos modelos aos dados experimentais nas três taxas de resfriamento utilizadas.
In this work, it was studied polymer composites made from a biodegradable polyester and natural coconut fibre (Cocus nucifera). Great abundance of this fibre can be found in the northeast areas of Brazil, and there are no reports in the literature of its use in polymer composites with poly (butylene-adipate-co-terephthalate). The use of coconut fiber in the formulations is an alternative for reducing costs, because it proposes a partial replacement for the polymer to be used. The study assessed the effects of the fibre on rheological and thermal properties of the biocomposites. Natural fibres were dried and classified before its utilization. Initially, the PBAT characterization was performed by differential scanning calorimetry in which were defined the melting temperature for processing in the rheometer. Composites of PBAT and coconut fibre were prepered with formulations containing 10, 20, 30, 40 and 50% in mass of fibre in the internal mixer. It was possible to quantify the dependence of torque with rotor speeds by the pseudoplasticity index through the power law. The rheological evaluation of the obtained composites showed the dependency on torque and temperature with the amount of fiber added. A study was conducted on composites crystallization of 10, 20 and 30% of fibre comparing it to the pure polymer submitted to the same conditions of preparation. Analysis of the results obtained by DSC indicated that the addition of fibres in the composite altered the crystallization temperature to higher values, suggesting that the fibres may have a nucleating effect. The composites when exposed to variations in the cooling rates, showed that the crystallization process is changed, displacing the crystallization peaks to lower temperatures as the cooling rate was increased. It was built the kinetic model of Pseudo-Avrami for the composite PBAT/10% coconut fibre, because its crystallization parameters showed lower error values or near 10% compared to pure PBAT. There was a good adjustment between models and experimental data in the three cooling rates utilized.
9
Abass, Abdul-Kariem. "Electrical and optical studies of lead phthalocynanine (PbPc) thin films." Thesis, Lancaster University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239800.
Full text
10
Reis, Pedro Rodrigo de Sousa. "Obtenção e caracterização de compósitos de blendas poliméricas biodegradáveis reforçadas com bio-hidroxiapatita." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-01112018-151923/.
Full textAbstract:
Este trabalho apresenta a preparação e caracterização de materiais compósitos baseados na mistura (blenda) de poli (ácido lático) PLA e poli (adipato co-tereftalato de butileno) PBAT reforçados com bio-hidroxiapatita \"HAp\", obtida a partir de cascas de ovos brancos de galinha. A obtenção de HAp foi realizada por via úmida, reação ácido-base. Primeiramente, foi obtido o bio-carbonato de cálcio a partir das cascas de ovos brancos de galinha, seguido de um ciclo térmico de aquecimento a 800 °C para a conversão em óxido de cálcio, o qual posteriormente foi sinterizado a 900 °C para a obtenção da HAp. Os materiais compósitos de PLA/PBAT reforçados com 1, 3 e 5 %, em massa, de HAp em pó, com tamanho de partículas iguais ou menor que 10 μm, foram preparadas pelo processo de extrusão utilizando-se uma extrusora de dupla-rosca. Após o processo de extrusão, os materiais foram alimentados ao funil de alimentação de uma injetora de laboratório para a obtenção dos corpos de prova para os ensaios de caracterização. Parte dos corpos de prova foram submetidos à esterilização por radiação gama (radioesterilização), utilizando-se feixe de elétrons de alta energia, gerados em um acelerador de elétrons industrial, de 1,5 MeV, à temperatura ambiente e na presença de ar, com dose de radiação de 25 kGy. As amostras de HAp foram caracterizadas por meio dos ensaios de difração de raios X (DRX), espectroscopia vibracional de absorção no infravermelho com transformada de Fourier (FTIR), termogravimetria (TG) e microscopia eletrônica de varredura com fonte de emissão de campo (MEV-FEG). O PLA/PBAT puro e seus compósitos não irradiados e irradiados foram caracterizados por meio dos ensaios de DRX, TG, MEV-FEG, calorimetria exploratória diferencial (DSC), temperatura de distorção térmica (HDT), ponto de amolecimento Vicat, resistência à tração, à flexão e ao impacto Izod, validação do processo de esterilização (teste de carga microbiana (Biocarga ou Bioburden) e ensaios de esterilidade) e citotoxicidade \"in vitro\" pelo método de incorporação do vermelho neutro para avaliação da biocompatibilidade das amostras. As análises de DRX da HAp mostraram os picos característicos presentes na fase amorfa da HAp; os picos e bandas largas pertencentes aos grupos moleculares da HAp foram identificados por meio da análise por FTIR; a estabilidade térmica da HAp obtida foi confirmada por termogravimetria, a qual mostrou uma pequena perda de massa com o aumento da temperatura, devido à queima do solvente, evaporação de água e queima de materiais orgânicos presentes na amostra de HAp, as imagens obtidas por MEV-FEG mostraram estruturas irregulares características da HAp. A incorporação de HAp na blenda de PLA/PBAT promoveu ganhos superiores a 10 % na temperatura de distorção térmica e no ponto de amolecimento Vicat original da blenda, aumento superior a 15 % nas propriedades mecânicas de resistência à tração e à flexão, e aumento superior a 10 % a resistência ao impacto Izod, melhorando suas propriedades de forma significativa quando comparado a blenda de PLA/PBAT. Os testes de carga microbiana e esterilidade mostraram que a dose de radiação de 25 kGy aplicada foi eficaz para a esterilização das amostras dos materiais. Todas as amostras apresentaram-se biocompatíveis em ambiente celular pelo teste de citotoxicidade \"in vitro\", apresentando potencial para estudo \"in vivo\".This work presents the preparation and characterization of composites based on blends of poly (lactic acid) - PLA and poly (adipate co-terephthalate of butylene) - PBAT reinforced with bio-hydroxyapatite \"HAp\", obtained from avian eggshells waste of white color. The HAp was obtained by the wet chemical method from the acid-base reaction. Firstly, the bio-calcium carbonate (bio-CaCO3) was obtained from the avian eggshells waste. The bio-CaCO3 was submitted to a heating cycle at 800 °C in order to convert bio-CaCO3 in the bio-calcium oxide, which was then sintered at 900 °C and the bio-HAp was obtained. PLA/PBAT reinforced with 1, 3 and 5 % in weight of HAp, particle size ≤ 10 μm, were prepared by the extrusion process using a twin-screw extruder. After the extrusion process, the PLA/PBAT blend and its composites were fed into a laboratory injection molding machine and the specimens test were obtained for the characterization tests. Part of the specimens was submitted to sterilization by gamma radiation (radio-sterilization) with electron-beam using an industrial electron accelerator of 1.5 MeV, at the radiation dose of 25 kGy, room temperature and in the presence of air. HAp was characterized by X ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and scanning electron microscopy with field emission source (FE-SEM) analysis. The blends and composites (non-irradiated and irradiated samples) were characterized by XRD; TG; FE-SEM and differential scanning calorimetry (DSC) analysis. The thermal distortion temperature (HDT), Vicat softening temperature, tensile, flexural, and impact Izod tests were also carried out. The validation of materials sterilization process (Bioburden tests) and cytotoxicity test \"in vitro\" to evaluating the biocompatibility of the material composites were also made. XRD analyzes results showed a characteristic peak in the amorphous phase of HAp. FTIR analysis identified broad peaks and bands belonging to the molecular groups of HAp. The thermal stability of the HAp was confirmed by the TG analysis, which showed a small loss of mass with the increase of temperature due to the burning of solvents, water evaporation and burning of organic materials present in the sample of HAp. The FE-SEM images showed irregular structures characteristic of HAp. Regarding the PLA/PBAT/HAP composites, it can be observed increases up to 10 % in thermal distortion temperature and Vicat softening temperature, higher than 15 % in the tensile and flexural strength, and higher than 10 % in the Izod impact when compared with neat PLA/PBAT blend. The bioburden tests showed that radiation dose of 25 kGy was effective for sterilization of the materials. The results of the cytotoxicity test \"in vitro\" showed that all samples are biocompatible in the cellular environment, and therefore, presents a potential for \"in vivo\" study.
Books on the topic "PBAC"
1
Division, United States General Accounting Office Accounting and Information Management. PBGC. Washington, D.C: The Office, 1995.
Find full text
2
Corporation, Pension Benefit Guaranty, ed. Divorce orders & PBGC. [Washington, D.C.]: PBGC, 1996.
Find full text
3
Corporation, Pension Benefit Guaranty, ed. Divorce orders & PBGC. [Washington, D.C.]: PBGC, 1996.
Find full text
4
Corporation, Pension Benefit Guaranty, ed. Divorce orders & PBGC. [Washington, D.C.]: PBGC, 1996.
Find full text
5
Corporation, Pension Benefit Guaranty, ed. Divorce orders & PBGC. [Washington, D.C.]: PBGC, 1996.
Find full text
6
Corporation, Pension Benefit Guaranty, ed. Divorce orders & PBGC. [Washington, D.C.]: PBGC, 1996.
Find full text
7
Corporation, Pension Benefit Guaranty, ed. Divorce orders & PBGC. [Washington, D.C.]: PBGC, 1996.
Find full text
8
Corporation, Pension Benefit Guaranty, ed. Divorce orders & PBGC. [Washington, D.C.]: PBGC, 1996.
Find full text
9
Pension Benefit Guaranty Corporation. Insurance Operations Dept, ed. Your guide to PBGC payments. Washington, DC (P.O. Box 19153, Washington 20036-0153): Pension Benefit Guaranty Corporation, Insurance Operations Dept., 1999.
Find full text
10
Pension Benefit Guaranty Corporation. Insurance Operations Dept., ed. Your guide to PBGC payments. Washington, DC (P.O. Box 19153, Washington 20036-0153): Pension Benefit Guaranty Corporation, Insurance Operations Dept., 1997.
Find full textBook chapters on the topic "PBAC"
1
Ivars, Ignacio Más, and Gunnar Karlsson. "PBAC: Probe-Based Admission Control." In Quality of Future Internet Services, 97–109. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/3-540-45412-8_8.
Full text
2
Lang, Ulrich, and Rudolf Schreiner. "Proximity-Based Access Control (PBAC) using Model-Driven Security." In ISSE 2015, 157–70. Wiesbaden: Springer Fachmedien Wiesbaden, 2015. http://dx.doi.org/10.1007/978-3-658-10934-9_14.
Full text
3
Frank, J. Howard, J. Howard Frank, Michael C. Thomas, Allan A. Yousten, F. William Howard, Robin M. Giblin-davis, John B. Heppner, et al. "Pban." In Encyclopedia of Entomology, 2766. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6359-6_2810.
Full text
4
Gooch, Jan W. "PBAN." In Encyclopedic Dictionary of Polymers, 521. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_8476.
Full text
5
Donato, Dominique M., Steven K. Hanks, Kenneth A. Jacobson, M. P. Suresh Jayasekara, Zhan-Guo Gao, Francesca Deflorian, John Papaconstantinou, et al. "PBAF RSC." In Encyclopedia of Signaling Molecules, 1348. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4419-0461-4_101000.
Full text
6
Braun-Falco, Markus, Henry J. Mankin, Sharon L. Wenger, Markus Braun-Falco, Stephan DiSean Kendall, Gerard C. Blobe, Christoph K. Weber, et al. "PBC." In Encyclopedia of Molecular Mechanisms of Disease, 1592. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-29676-8_8143.
Full text
7
Invernizzi, Pietro. "PBC Genetics." In Encyclopedia of Medical Immunology, 840–46. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-0-387-84828-0_516.
Full text
8
Lozano-Ojalvo, Daniel, Rosina López-Fandiño, and Iván López-Expósito. "PBMC-Derived T Cells." In The Impact of Food Bioactives on Health, 169–80. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-16104-4_16.
Full text
9
Löding, Christof, and Anton Pirogov. "Ambiguity, Weakness, and Regularity in Probabilistic Büchi Automata." In Lecture Notes in Computer Science, 522–41. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45231-5_27.
Full textAbstract:
AbstractProbabilistic Büchi automata are a natural generalization of PFA to infinite words, but have been studied in-depth only rather recently and many interesting questions are still open. PBA are known to accept, in general, a class of languages that goes beyond the regular languages. In this work we extend the known classes of restricted PBA which are still regular, strongly relying on notions concerning ambiguity in classical $$\omega $$ ω -automata. Furthermore, we investigate the expressivity of the not yet considered but natural class of weak PBA, and we also show that the regularity problem for weak PBA is undecidable.
10
van Buuren, H. R. "Corticosteroids in PBC." In Primary Biliary Cirrhosis, 130–37. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-4884-9_16.
Full textConference papers on the topic "PBAC"
1
Wu, Haiyan, Chengxiang Tan, and Haihang Wang. "A Hybrid RBAC-PBAC Access Control Model for Network Isolation System." In First International Workshop on Knowledge Discovery and Data Mining (WKDD 2008). IEEE, 2008. http://dx.doi.org/10.1109/wkdd.2008.120.
Full text
2
Sodiya, Adesina, and Adebukola Onashoga. "Components- Based Access Control Architecture." In InSITE 2009: Informing Science + IT Education Conference. Informing Science Institute, 2009. http://dx.doi.org/10.28945/3374.
Full textAbstract:
Ensuring adequate security of information has been a growing concern of individuals and organizations. There is then the need to provide suitable access control mechanism for preventing insider abuses and ensuring appropriate use of resources. This paper presents an access control scheme that adopts the techniques of Role-Based Access Control (RBAC), Purpose-Based Access Control (PBAC), Time-Based Access Control (TBAC) and History-Based Access Control (HBAC) as components to form an integrated Components-based Access Control Architecture (CACA). In CACA, an Access Control Score (ACS) is computed from the combined access control techniques. CACA also combines ACS with the sensitivity nature of system resources before a level of access is granted. The architecture was implemented within a payroll system developed using JAVA and SQL. Using usability testing, the evaluation of CACA showed 92% reduction in insider abuses and misuse of privileges. This shows that CACA can provide higher level of security access as against what used to exist.
3
Azzam, R. M. A. "Analytical determination of the complex refractive index of an opaque film deposited on a transparent substrate from the pseudo-Brewster angles of internal and external reflection." In Optical Interference Coatings. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oic.1988.wc5.
Full textAbstract:
A new method is described for the explicit determination of the refractive index amd extinction coefficient of an opaque film deposited on a transparent substrate from purely angular, nonpolarimetric, measurements. In particular it is shown that the real and imaginary parts of the complex dielectric constant ε = εr –j εi of the film are obtained analytically, directly and noniteratively, from the pseudo-Brewster angles (PBAs) of internal and external reflection. This follows from a study of the properties of the contours of constant PBA in the complex ε plane. For this method to be accurate, one of the two PBAs should be <45°, i.e. the substrate should be sufficiently optically dense or the UV and VUV spectral range is of interest. Experimental errors of the PBAs may also render impossible the determination of εi when |εi/εr|≪1. Simulated measurements on Ag and TiN films will be presented to demonstrate the method.
4
Ahmad Hairi, Amelia Najwa, Ungku Fatimah Ungku Zainal Abidin, Maimunah Sanny, and Nur Qistina Aznor Shahril. "Consumers' Perceptions and Associations on Plant-based Cheese Analogue in Malaysia." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/oftn5374.
Full textAbstract:
Plant-based cheese analogue (PBCA) has just started to debut in the plant-based dairy product market in Malaysia. Despite that, no research has been made on the consumers’ view on PBCA in Malaysia. This study attempts to identify the Malaysian consumers’ purchase intention of PBCA, assess the consumers’ associations evoked by cheese, and discover any differences in the perceptions of cheese and expectations toward PBCA of consumers. A quantitative online survey was conducted among cheese and PBCA consumers in Malaysia and results showed that purchase intention is the significant predictor behaviour to consume PBCA. Consumers’ attitude, subjective norm, and perceived barriers significantly influenced the purchase intention of PBCA but objective knowledge, perceived behavioural control and health consciousness showed otherwise. The study also shows that the consumers from different household groups perceive cheese and PBCA positively which shows the acceptance towards the products in the population. It can be concluded that consumers in Malaysia had a same direction in viewing PBCA. This research would benefit the local food industry players to understand more about the consumers’ view and aid them in producing a product that suits their needs.
5
Si, P., J. Zou, J. F. Ying, Y. H. Zhang, F. F. Wang, and Y. Z. Qi. "Photooxidation aging behavior of PLA/PBAT films with different PBAT contents." In The 2015 International Conference on Sustainable Development (ICSD2015). WORLD SCIENTIFIC, 2016. http://dx.doi.org/10.1142/9789814749916_0080.
Full text
6
Radovanovic, M. "IntroductionWhy PBC?" In Advanced Course in Fluidized Bed Combustion. Connecticut: Begellhouse, 1986. http://dx.doi.org/10.1615/ichmt.1986.advcoursefluidbedcomb.20.
Full text
7
Wang, Jinsu, Sharad Mehrotra, and Nalini Venkatasubramanian. "PBCA - Prediction Based Channel Allocation." In IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference. IEEE, 2007. http://dx.doi.org/10.1109/glocom.2007.911.
Full text
8
Le Berre, Daniel, Pierre Marquis, Stefan Mengel, and Romain Wallon. "Pseudo-Boolean Constraints from a Knowledge Representation Perspective." In Twenty-Seventh International Joint Conference on Artificial Intelligence {IJCAI-18}. California: International Joint Conferences on Artificial Intelligence Organization, 2018. http://dx.doi.org/10.24963/ijcai.2018/261.
Full textAbstract:
We study pseudo-Boolean constraints (PBC) and their special case cardinality constraints (CARD) from the perspective of knowledge representation. To this end, the succinctness of PBC and CARD is compared to that of many standard propositional languages. Moreover, we determine which queries and transformations are feasible in polynomial time when knowledge is represented by PBC or CARD, and which are not (unconditionally or unless P = NP). In particular, the advantages and disadvantages compared to CNF are discussed.
9
Barbee, Gibson, and Philippe Westreich. "NS 999 Electric Switcher Update." In ASME 2013 Rail Transportation Division Fall Technical Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/rtdf2013-4708.
Full textAbstract:
Norfolk Southern Railway Company (NS) is developing an all-electric switching locomotive, the NS 999, to provide a zero point source emission electric locomotive option for rail switching service. The original NS 999, unveiled in September 2009, suffered from poor battery management and challenging battery packaging. The rebuilt NS 999, anticipated in the 4th quarter 2013, will be powered by Axion Power’s PbC® batteries. The Axion PbC® batteries provide increased charge/discharge cycle life and charge acceptance compared to conventional Valve Regulated Lead–Acid (VRLA) batteries, as well as increased usable energy when configured in series as ‘long strings.’ NS and Axion will review the challenges of the initial NS 999 battery management system, improvements to the battery management system, and test results from the Norfolk Southern Hybrid Locomotive Simulator using Axion’s PbC® lead–carbon hybrid battery/supercapacitor. Axion will present test data showing the low variation in strings of PbC® batteries compared to VRLA while simulating locomotive switching. PbC® batteries have a unique charging curve, known as “concave down, increasing,” which allows the batteries to self-equalize in strings. This characteristic of PbC® batteries provides for simpler battery management and reduced maintenance charging, while increasing the usable energy available within the string. The rebuilt experimental locomotive NS 999 will use Axion’s PbC® lead–carbon batteries for the energy storage system to power locomotive switching and recover braking energy. If this research is successful, a zero point source emission electric locomotive could provide an option to reduce emissions in urban non-attainment areas and reduce dependence on petroleum. The NS 999 electric switcher is the first step to the ultimate goal of recovering braking energy from high power conventional diesel locomotives.
10
Alleyne, Andrew. "Passivity-Based Nonlinear Control Strategies for Strict Feedback Form Systems." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0018.
Full textAbstract:
Abstract This paper presents a tracking algorithm for the control of nonlinear dynamic systems represented in Strict Feedback Form. The construction of the stabilizing algorithm is given using Passivity-based arguments which result in a Passivity-Based Controller (PBC). Also shown are simulations demonstrating the performance of the suggested approach. This paper also shows a direct comparison with the most popular control strategy for Strict Feedback Form Systems: Integrator Backstepping. It is shown that although Integrator Backstepping has several advantages, most notably flexibility in designing output feedback and adaptive approaches, there do exist important situations that favor the PBC. When the model structure is poorly known, the PBC contains diagnostic effects allowing it to systematically pinpoint parts of the model containing inaccuracies. Moreover, the PBC can be simpler to implement than the Backstepping algorithms in the non-adaptive, state feedback case.
Reports on the topic "PBAC"
1
Rafaeli, Ada, and Russell Jurenka. Molecular Characterization of PBAN G-protein Coupled Receptors in Moth Pest Species: Design of Antagonists. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7593390.bard.
Full textAbstract:
The proposed research was directed at determining the activation/binding domains and gene regulation of the PBAN-R’s thereby providing information for the design and screening of potential PBAN-R-blockers and to indicate possible ways of preventing the process from proceeding to its completion. Our specific aims included: (1) The identification of the PBAN-R binding domain by a combination of: (a) in silico modeling studies for identifying specific amino-acid side chains that are likely to be involved in binding PBAN with the receptor and; (b) bioassays to verify the modeling studies using mutant receptors, cell lines and pheromone glands (at tissue and organism levels) against selected, designed compounds to confirm if compounds are agonists or antagonists. (2) The elucidation ofthemolecular regulationmechanisms of PBAN-R by:(a) age-dependence of gene expression; (b) the effect of hormones and; (c) PBAN-R characterization in male hair-pencil complexes. Background to the topic Insects have several closely related G protein-coupled receptors (GPCRs) belonging to the pyrokinin/PBAN family, one with the ligand pheromone biosynthesis activating neuropeptide or pyrokinin-2 and another with diapause hormone or pyrokinin-1 as a ligand. We were unable to identify the diapause hormone receptor from Helicoverpa zea despite considerable effort. A third, related receptor is activated by a product of the capa gene, periviscerokinins. The pyrokinin/PBAN family of GPCRs and their ligands has been identified in various insects, such as Drosophila, several moth species, mosquitoes, Triboliumcastaneum, Apis mellifera, Nasoniavitripennis, and Acyrthosiphon pisum. Physiological functions of pyrokinin peptides include muscle contraction, whereas PBAN regulates pheromone production in moths plus other functions indicating the pleiotropic nature of these ligands. Based on the alignment of annotated genomic sequences, the primary and secondary structures of the pyrokinin/PBAN family of receptors have similarity with the corresponding structures of the capa or periviscerokinin receptors of insects and the neuromedin U receptors found in vertebrates. Major conclusions, solutions, achievements Evolutionary trace analysisof receptor extracellular domains exhibited several class-specific amino acid residues, which could indicate putative domains for activation of these receptors by ligand recognition and binding. Through site-directed point mutations, the 3rd extracellular domain of PBAN-R was shown to be critical for ligand selection. We identified three receptors that belong to the PBAN family of GPCRs and a partial sequence for the periviscerokinin receptor from the European corn borer, Ostrinianubilalis. Functional expression studies confirmed that only the C-variant of the PBAN-R is active. We identified a non-peptide agonist that will activate the PBAN-receptor from H. zea. We determined that there is transcriptional control of the PBAN-R in two moth species during the development of the pupa to adult, and we demonstrated that this transcriptional regulation is independent of juvenile hormone biosynthesis. This transcriptional control also occurs in male hair-pencil gland complexes of both moth species indicating a regulatory role for PBAN in males. Ultimate confirmation for PBAN's function in the male tissue was revealed through knockdown of the PBAN-R using RNAi-mediated gene-silencing. Implications, both scientific and agricultural The identification of a non-peptide agonist can be exploited in the future for the design of additional compounds that will activate the receptor and to elucidate the binding properties of this receptor. The increase in expression levels of the PBAN-R transcript was delineated to occur at a critical period of 5 hours post-eclosion and its regulation can now be studied. The mysterious role of PBAN in the males was elucidated by using a combination of physiological, biochemical and molecular genetics techniques.
2
Malamud, E. The Fermilab Pbar Collider: Machine and Detectors. Office of Scientific and Technical Information (OSTI), February 1985. http://dx.doi.org/10.2172/948918.
Full text
3
Rafaeli, Ada, Russell Jurenka, and Daniel Segal. Isolation, Purification and Sequence Determination of Pheromonotropic-Receptors. United States Department of Agriculture, July 2003. http://dx.doi.org/10.32747/2003.7695850.bard.
Full textAbstract:
Moths constitute a major group of pest insects in agriculture. Pheromone blends are utilised by a variety of moth species to attract conspecific mates, which is under circadian control by the neurohormone, PBAN (pheromone-biosynthesis-activating neuropeptide). Our working hypothesis was that, since the emission of sex-pheromone is necessary to attract a mate, then failure to produce and emit pheromone is a potential strategy for manipulating adult moth behavior. The project aimed at identifying, characterising and determining the sequence of specific receptors responsible for the interaction with pheromonotropic neuropeptide/s using two related moth species: Helicoverpa armigera and H. lea as model insects. We established specific binding to a membrane protein estimated at 50 kDa in mature adult females using a photoaffinity-biotin probe for PBAN. We showed that JH is required for the up-regulation of this putative receptor protein. In vitro studies established that the binding initiates a cascade of second messengers including channel opening for calcium ions and intracellular cAMP production. Pharmacological studies (using sodium fluoride) established that the receptor is coupled to a G-protein, that is, the pheromone-biosynthesis-activating neuropeptide receptor (PBAN-R) belongs to the family of G protein-coupled receptor (GPCR)'s. We showed that PBAN-like peptides are present in Drosophila melanogaster based on bioassay and immunocytochemical data. Using the annotated genome of D. melanogaster to search for a GPCR, we found that some were similar to neuromedin U- receptors of vertebrates, which contain a similar C-terminal ending as PBAN. We established that neuromedin U does indeed induce pheromone biosynthesis and cAMP production. Using a PCR based cloning strategy and mRNA isolated from pheromone glands of H. zea, we successfully identified a gene encoding a GPCR from pheromone glands. The full-length PBAN-R was subsequently cloned and expressed in Sf9 insect cells and was shown to mobilize calcium in response to PBAN in a dose-dependent manner. The successful progress in the identification of a gene, encoding a GPCR for the neurohormone, PBAN, provides a basis for the design of a novel battery of compounds that will specifically antagonize pheromone production. Furthermore, since PBAN belongs to a family of insect neuropeptides with more than one function in different life stages, this rationale may be extended to other physiological key-regulatory processes in different insects.
4
Bhat, C. M. Some design considerations for pbar target sweeping station. Office of Scientific and Technical Information (OSTI), June 1991. http://dx.doi.org/10.2172/5616995.
Full text
5
Rafaeli, Ada, Russell Jurenka, and Chris Sander. Molecular characterisation of PBAN-receptors: a basis for the development and screening of antagonists against Pheromone biosynthesis in moth pest species. United States Department of Agriculture, January 2008. http://dx.doi.org/10.32747/2008.7695862.bard.
Full textAbstract:
The original objectives of the approved proposal included: (a) The determination of species- and tissue-specificity of the PBAN-R; (b) the elucidation of the role of juvenile hormone in gene regulation of the PBAN-R; (c) the identificationof the ligand binding domains in the PBAN-R and (d) the development of efficient screening assays in order to screen potential antagonists that will block the PBAN-R. Background to the topic: Moths constitute one of the major groups of pest insects in agriculture and their reproductive behavior is dependent on chemical communication. Sex-pheromone blends are utilised by a variety of moth species to attract conspecific mates. In most of the moth species sex-pheromone biosynthesis is under circadian control by the neurohormone, PBAN (pheromone-biosynthesis-activating neuropeptide). In order to devise ideal strategies for mating disruption/prevention, we proposed to study the interactions between PBAN and its membrane-bound receptor in order to devise potential antagonists. Major conclusions: Within the framework of the planned objectives we have confirmed the similarities between the two Helicoverpa species: armigera and zea. Receptor sequences of the two Helicoverpa spp. are 98% identical with most changes taking place in the C-terminal. Our findings indicate that PBAN or PBAN-like receptors are also present in the neural tissues and may represent a neurotransmitter-like function for PBAN-like peptides. Surprisingly the gene encoding the PBAN-receptor was also present in the male homologous tissue, but it is absent at the protein level. The presence of the receptor (at the gene- and protein-levels), and the subsequent pheromonotropic activity are age-dependent and up-regulated by Juvenile Hormone in pharate females but down-regulated by Juvenile Hormone in adult females. Lower levels of pheromonotropic activity were observed when challenged with pyrokinin-like peptides than with HezPBAN as ligand. A model of the 3D structure of the receptor was created using the X-ray structure of rhodopsin as a template after sequence alignment of the HezPBAN-R with several other GPCRs and computer simulated docking with the model predicted putative binding sites. Using in silico mutagenesis the predicted docking model was validated with experimental data obtained from expressed chimera receptors in Sf9 cells created by exchanging between the three extracellular loops of the HezPBAN-R and the Drosophila Pyrokinin-R (CG9918). The chimera receptors also indicated that the 3ʳᵈ extracellular loop is important for recognition of PBAN or Diapause hormone ligands. Implications: The project has successfully completed all the objectives and we are now in a position to be able to design and screen potential antagonists for pheromone production. The successful docking simulation-experiments encourage the use of in silico experiments for initial (high-throughput) screening of potential antagonists. However, the differential responses between the expressed receptor (Sf9 cells) and the endogenous receptor (pheromone glands) emphasize the importance of assaying lead compounds using several alternative bioassays (at the cellular, tissue and organism levels). The surprising discovery of the presence of the gene encoding the PBAN-R in the male homologous tissue, but its absence at the protein level, launches opportunities for studying molecular regulation pathways and the evolution of these GPCRs. Overall this research will advance research towards the goal of finding antagonists for this important class of receptors that might encompass a variety of essential insect functions.
6
Altstein, Miriam, and Ronald J. Nachman. Rational Design of Insect Control Agent Prototypes Based on Pyrokinin/PBAN Neuropeptide Antagonists. United States Department of Agriculture, August 2013. http://dx.doi.org/10.32747/2013.7593398.bard.
Full textAbstract:
The general objective of this study was to develop rationally designed mimetic antagonists (and agonists) of the PK/PBAN Np class with enhanced bio-stability and bioavailability as prototypes for effective and environmentally friendly pest insect management agents. The PK/PBAN family is a multifunctional group of Nps that mediates key functions in insects (sex pheromone biosynthesis, cuticular melanization, myotropic activity, diapause and pupal development) and is, therefore, of high scientific and applied interest. The objectives of the current study were: (i) to identify an antagonist biophores (ii) to develop an arsenal of amphiphilic topically active PK/PBAN antagonists with an array of different time-release profiles based on the previously developed prototype analog; (iii) to develop rationally designed non-peptide SMLs based on the antagonist biophore determined in (i) and evaluate them in cloned receptor microplate binding assays and by pheromonotropic, melanotropic and pupariation in vivo assays. (iv) to clone PK/PBAN receptors (PK/PBAN-Rs) for further understanding of receptor-ligand interactions; (v) to develop microplate binding assays for screening the above SMLs. In the course of the granting period A series of amphiphilic PK/PBAN analogs based on a linear lead antagonist from the previous BARD grant was synthesized that incorporated a diverse array of hydrophobic groups (HR-Suc-A[dF]PRLa). Others were synthesized via the attachment of polyethylene glycol (PEG) polymers. A hydrophobic, biostablePK/PBAN/DH analog DH-2Abf-K prevented the onset of the protective state of diapause in H. zea pupae [EC50=7 pmol/larva] following injection into the preceding larval stage. It effectively induces the crop pest to commit a form of ‘ecological suicide’. Evaluation of a set of amphiphilic PK analogs with a diverse array of hydrophobic groups of the formula HR-Suc-FTPRLa led to the identification of analog T-63 (HR=Decyl) that increased the extent of diapause termination by a factor of 70% when applied topically to newly emerged pupae. Another biostablePK analog PK-Oic-1 featured anti-feedant and aphicidal properties that matched the potency of some commercial aphicides. Native PK showed no significant activity. The aphicidal effects were blocked by a new PEGylated PK antagonist analog PK-dF-PEG4, suggesting that the activity is mediated by a PK/PBAN receptor and therefore indicative of a novel and selective mode-of-action. Using a novel transPro mimetic motif (dihydroimidazole; ‘Jones’) developed in previous BARD-sponsored work, the first antagonist for the diapause hormone (DH), DH-Jo, was developed and shown to block over 50% of H. zea pupal diapause termination activity of native DH. This novel antagonist development strategy may be applicable to other invertebrate and vertebrate hormones that feature a transPro in the active core. The research identifies a critical component of the antagonist biophore for this PK/PBAN receptor subtype, i.e. a trans-oriented Pro. Additional work led to the molecular cloning and functional characterization of the DH receptor from H. zea, allowing for the discovery of three other DH antagonist analogs: Drosophila ETH, a β-AA analog, and a dF analog. The receptor experiments identified an agonist (DH-2Abf-dA) with a maximal response greater than native DH. ‘Deconvolution’ of a rationally-designed nonpeptide heterocyclic combinatorial library with a cyclic bis-guanidino (BG) scaffold led to discovery of several members that elicited activity in a pupariation acceleration assay, and one that also showed activity in an H. zea diapause termination assay, eliciting a maximal response of 90%. Molecular cloning and functional characterization of a CAP2b antidiuretic receptor from the kissing bug (R. prolixus) as well as the first CAP2b and PK receptors from a tick was also achieved. Notably, the PK/PBAN-like receptor from the cattle fever tick is unique among known PK/PBAN and CAP2b receptors in that it can interact with both ligand types, providing further evidence for an evolutionary relationship between these two NP families. In the course of the granting period we also managed to clone the PK/PBAN-R of H. peltigera, to express it and the S. littoralis-R Sf-9 cells and to evaluate their interaction with a variety of PK/PBAN ligands. In addition, three functional microplate assays in a HTS format have been developed: a cell-membrane competitive ligand binding assay; a Ca flux assay and a whole cell cAMP ELISA. The Ca flux assay has been used for receptor characterization due to its extremely high sensitivity. Computer homology studies were carried out to predict both receptor’s SAR and based on this analysis 8 mutants have been generated. The bioavailability of small linear antagonistic peptides has been evaluated and was found to be highly effective as sex pheromone biosynthesis inhibitors. The activity of 11 new amphiphilic analogs has also been evaluated. Unfortunately, due to a problem with the Heliothis moth colony we were unable to select those with pheromonotropic antagonistic activity and further check their bioavailability. Six peptides exhibited some melanotropic antagonistic activity but due to the low inhibitory effect the peptides were not further tested for bioavailability in S. littoralis larvae. Despite the fact that no new antagonistic peptides were discovered in the course of this granting period the results contribute to a better understanding of the interaction of the PK/PBAN family of Nps with their receptors, provided several HT assays for screening of libraries of various origin for presence of PK/PBAN-Ragonists and antagonists and provided important practical information for the further design of new, peptide-based insecticide prototypes aimed at the disruption of key neuroendocrine physiological functions in pest insects.
7
Dugan, G. Estimate of the Pbar Yields for the CERN ACOL Project. Office of Scientific and Technical Information (OSTI), May 1986. http://dx.doi.org/10.2172/948890.
Full text
8
Bhat, C. M. Pbar Beam Stacking in the Recycler by Longitudinal Phase-space Coating. Office of Scientific and Technical Information (OSTI), August 2013. http://dx.doi.org/10.2172/1128476.
Full text
9
Baich, M. A. IIT B52 Antifoam Impact Upon PBA Hydrolysis Kinetics. Office of Scientific and Technical Information (OSTI), June 2001. http://dx.doi.org/10.2172/781740.
Full text
10
Cave, William C. The Theoretical Underpinnings of Predictive Battlespace Awareness (PBA). Fort Belvoir, VA: Defense Technical Information Center, July 2003. http://dx.doi.org/10.21236/ada418602.
Full text