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1
Kilic, Keziban. « CNDA : une réforme de façade ». Plein droit 105, no 2 (2015) : 22. http://dx.doi.org/10.3917/pld.105.0022.
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Chen, Qing, Cheng-Hong Wang, Shi-Kai Deng, Ya-Dong Wu, Yi Li, Li Yao, Jian-Dong Jiang, Xin Yan, Jian He et Shun-Peng Li. « Novel Three-Component Rieske Non-Heme Iron Oxygenase System Catalyzing theN-Dealkylation of Chloroacetanilide Herbicides in Sphingomonads DC-6 and DC-2 ». Applied and Environmental Microbiology 80, no 16 (13 juin 2014) : 5078–85. http://dx.doi.org/10.1128/aem.00659-14.
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ABSTRACTSphingomonads DC-6 and DC-2 degrade the chloroacetanilide herbicides alachlor, acetochlor, and butachlor viaN-dealkylation. In this study, we report a three-component Rieske non-heme iron oxygenase (RHO) system catalyzing theN-dealkylation of these herbicides. The oxygenase component genecndAis located in a transposable element that is highly conserved in the two strains. CndA shares 24 to 42% amino acid sequence identities with the oxygenase components of some RHOs that catalyzeN- orO-demethylation. Two putative [2Fe-2S] ferredoxin genes and one glutathione reductase (GR)-type reductase gene were retrieved from the genome of each strain. These genes were not located in the immediate vicinity ofcndA. The four ferredoxins share 64 to 72% amino acid sequence identities to the ferredoxin component of dicambaO-demethylase (DMO), and the two reductases share 62 to 65% amino acid sequence identities to the reductase component of DMO.cndA, the four ferredoxin genes, and the two reductases genes were expressed inEscherichia coli, and the recombinant proteins were purified using Ni-affinity chromatography. The individual components or the components in pairs displayed no activity; the enzyme mixture showedN-dealkylase activities toward alachlor, acetochlor, and butachlor only when CndA-His6was combined with one of the four ferredoxins and one of the two reductases, suggesting that the enzyme consists of three components, a homo-oligomer oxygenase, a [2Fe-2S] ferredoxin, and a GR-type reductase, and CndA has a low specificity for the electron transport component (ETC). TheN-dealkylase utilizes NADH, but not NADPH, as the electron donor.
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Liu, F., H. Liu, S. Liu, B. Liu, L. Lei, C. Chen et Y. Wu. « Nb3Sn Strand Verification for ITER TF Conductors of CNDA ». Fusion Science and Technology 66, no 1 (août 2014) : 208–13. http://dx.doi.org/10.13182/fst13-729.
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Long, Feng, Fang Liu, Yu Wu et Zhipeng Ni. « The First Benchmarking of ITER BR Nb3Sn Strand of CNDA ». Plasma Science and Technology 14, no 9 (septembre 2012) : 847–49. http://dx.doi.org/10.1088/1009-0630/14/9/14.
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El Amri, A., et J. P. Hilger. « Etude calorimétrique du revenu de l’acier Z3 CNDA 13-08 ». Revue de Métallurgie 90, no 5 (mai 1993) : 629–36. http://dx.doi.org/10.1051/metal/199390050629.
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Robineau, Virginie, Aurélia Malhou et Marie Daniès. « Quels enjeux de l’interprétariat sur le recours à la CNDA ? » Mémoires N° 87, no 3 (27 février 2024) : 18–19. http://dx.doi.org/10.3917/mem.087.0018.
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Xu, Xingya, et Mitsuhiro Yanagida. « Suppressor screening reveals common kleisin–hinge interaction in condensin and cohesin, but different modes of regulation ». Proceedings of the National Academy of Sciences 116, no 22 (9 mai 2019) : 10889–98. http://dx.doi.org/10.1073/pnas.1902699116.
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Cohesin and condensin play fundamental roles in sister chromatid cohesion and chromosome segregation, respectively. Both consist of heterodimeric structural maintenance of chromosomes (SMC) subunits, which possess a head (containing ATPase) and a hinge, intervened by long coiled coils. Non-SMC subunits (Cnd1, Cnd2, and Cnd3 for condensin; Rad21, Psc3, and Mis4 for cohesin) bind to the SMC heads. Here, we report a large number of spontaneous extragenic suppressors for fission yeast condensin and cohesin mutants, and their sites were determined by whole-genome sequencing. Mutants of condensin’s non-SMC subunits were rescued by impairing the SUMOylation pathway. Indeed, SUMOylation of Cnd2, Cnd3, and Cut3 occurs in midmitosis, and Cnd3 K870 SUMOylation functionally opposes Cnd subunits. In contrast, cohesin mutants rad21 and psc3 were rescued by loss of the RNA elimination pathway (Erh1, Mmi1, and Red1), and loader mutant mis4 was rescued by loss of Hrp1-mediated chromatin remodeling. In addition, distinct regulations were discovered for condensin and cohesin hinge mutants. Mutations in the N-terminal helix bundle [containing a helix–turn–helix (HTH) motif] of kleisin subunits (Cnd2 and Rad21) rescue virtually identical hinge interface mutations in cohesin and condensin, respectively. These mutations may regulate kleisin’s interaction with the coiled coil at the SMC head, thereby revealing a common, but previously unknown, suppression mechanism between the hinge and the kleisin N domain, which is required for successful chromosome segregation. We propose that in both condensin and cohesin, the head (or kleisin) and hinge may interact and collaboratively regulate the resulting coiled coils to hold and release chromosomal DNAs.
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Liu, F., H. Liu, S. Liu, B. Liu, L. Lei et Y. Wu. « NbTi Strands Verification for ITER PF CICC Process Qualification of CNDA ». Journal of Physics : Conference Series 507, no 3 (12 mai 2014) : 032029. http://dx.doi.org/10.1088/1742-6596/507/3/032029.
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Liu, Fang, Feng Long, Bo Liu, Lei Lei, Yu Wu et Huajun Liu. « Implementation and analysis of ITER strand test of CNDA for world-wide benchmarking ». Fusion Engineering and Design 88, no 1 (janvier 2013) : 17–22. http://dx.doi.org/10.1016/j.fusengdes.2012.09.010.
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Monopoli, Antonio, Giovanni Ventura, Andrea Aloia, Fulvio Ciriaco, Angelo Nacci, Tommaso R. I. Cataldi et Cosima D. Calvano. « Synthesis and Investigation of Novel CHCA-Derived Matrices for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric Analysis of Lipids ». Molecules 27, no 8 (15 avril 2022) : 2565. http://dx.doi.org/10.3390/molecules27082565.
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A significant area of study and upgrading for increasing sensitivity and general performances of matrix-assisted laser-desorption ionization (MALDI) mass spectrometry (MS) is related to matrix design. Several efforts have been made to address the challenge of low-mass-region interference-free for metabolomics analysis and specifically for lipidomics. To this aim, rationally designed matrices as 4-chloro-α-cyanocinnamic acid (ClCCA) were introduced and reported to provide enhanced analytical performances. We have taken this rational design one step further by developing and optimizing new MALDI matrices with a range of modifications on the CHCA core, involving different functionalities and substituents. Of particular interest was the understanding of the electron-withdrawing (e.g., nitro-) or donating (e.g., methoxy-) effects along with the extent of conjugation on the ionization efficiency. In the present work, ten matrices were designed on a reasonable basis, synthesized, and characterized by NMR and UV spectroscopies and laser desorption ionization. With the assistance of these putative MALDI matrices, samples containing phospholipids (PL), and neutral di-/tri-acylglycerols (DAG, TAG) were investigated using milk, fish, blood, and human plasma extracts. In comparison with CHCA and ClCCA, four of them, viz. [(2E,4E)-2-cyano-5-(4-methoxyphenyl)penta-2,4-dienoic acid] (1), [(2E,4E)-2-cyano-5-(4-nitrophenyl)penta-2,4-dienoic acid] (2), [(E)-2-cyano-3-(6-methoxynaphthalen-2-yl)acrylic acid] (6) and [(E)-2-cyano-3-(naphthalen-2-yl)acrylic acid] (7) displayed good to even excellent performances as MALDI matrices in terms of ionization capability, interference-free spectra, S/N ratio, and reproducibility. Especially compound 7 (cyano naphthyl acrylic acid, CNAA) was the election matrix for PL analysis and matrix 2 (cyano nitrophenyl dienoic acid, CNDA) for neutral lipids such as DAG and TAG in positive ion mode.
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Chen, Mei Rong, Xing Shen, Lin Li et Song Qing Hu. « Cloning and Characterization of Three Genes Encoding LMW-GSs from Triticum aestivum, Cultival Cheyenne ». Advanced Materials Research 554-556 (juillet 2012) : 1116–20. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.1116.
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Three low molecular weight subunit genes, named LMW-CND1 (GeneBank accession JQ780048), LMW-CND2 (GeneBank accession JQ779840), LMW-CND3 (GeneBank accession JQ779841), with a ORF of 1053 bp, 903 bp, 969 bp, respectively, were isolated from cv. Cheyenne and characterized detailed in molecular level. The proteins encoded by the genes, with 350, 300, 322 amino acid residues respectively, differ only in repetitive domain of sequences due to insertion or deletion of repeats in this domain. Highly similarity in amino-acid sequence between these three subunits and other published LMW-GSs was also observed, showing that all three genes published here are typical LMW-GS genes and closely related to the genes on chromosome 1D. Besides, secondary structure prediction of proteins indicated that, in the three LMW-GSs, random loop accounts for no less than 70 %, α-helix amounts to 26 %, average, and only 1.4 %~1.7 % is β-sheet.
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Delarboulas, M., et R. Cozar. « Deuxième partie : Caractéristiques et possibilités d’applications aérospatiales de l’acier E Z 3 CNDA 13-08 ». Matériaux & ; Techniques 73, no 10-11 (1985) : 622–31. http://dx.doi.org/10.1051/mattech/198573100622.
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Liu, Xiaojun, Yingjun Jiang, Akira Matsuda et William Plunkett. « Homologous Recombination Repair of DNA Strand Breaks Induced by the Nucleoside Analogue CNDAG. » Blood 116, no 21 (19 novembre 2010) : 1189. http://dx.doi.org/10.1182/blood.v116.21.1189.1189.
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Abstract Abstract 1189 We hypothesize that the novel deoxyguanosine analogue CNDAG [9-(2-C-cyano-2-deoxy-1-β-D-arabino-pentofuranosyl) guanine] may share the common action mechanism with its cytosine congener CNDAC [2′-C-cyano-2′-deoxy-1-β-D-arabino-pentofuranosylcytosine], a prodrug of which, sapacitabine, is undergoing clinical trials in myeloid leukemias. CNDAC induces single strand breaks following incorporation into DNA. Subsequent processing or DNA replication across the unrepaired nicks would generate double strand breaks (DSBs) [1]. Because cytosine and guanine nucleoside congeners have remarkably different clinical activities, e.g., cytarabine (acute myelogenous leukemia) and nelarabine (T-cell malignancies), it will be useful to pursue investigations to fully characterize the metabolism and actions of CNDAG. This study was aimed at defining cellular response and damage repair mechanisms for two CNDAG prodrugs, 2-amino-9-(2-C-cyano-2-deoxy-1-β-D-arabino-pentofuranosyl)-6-methoxy purine (6-OMe) and 9-(2-C-cyano-2-deoxy-1-β-D-arabino-pentofuranosyl)-2,6-diaminopurine (6-NH2). Each prodrug is a substrate for adenosine deaminase (ADA), the action of which generates CNDAG. First, growth inhibition by both CNDAG prodrugs was dependent upon both concentration and time of exposure; the proliferation of T-cell malignant lines (CCRF-CEM and Jurkat) was suppressed more to B-cell lines (Raji and IM-9). This may be attributed to relatively low activity of deoxycytidine kinase in the latter cell lines. Second, p53 knocked-out and parental HCT116 cells were equally sensitive to CNDAG 6-NH2 in a clonogenic assay, indicating that cytotoxicity of CNDAG is independent of p53 status. Third, similar to CNDAC, CNDAG prodrugs activated repair proteins in multiple DNA damage response pathways, as revealed by immunoblotting. 24-hr incubation of CCRF-CEM cells with 50 microM either prodrug increased the phosphorylation of Ser-1981 on ATM, Ser-345 on Chk1, Thr-68 on Chk2, Ser-966 on SMC1, Ser-343 on Nbs1 and g-H2AX. In contrast, there was no increase in phosphorylation of two other sensor kinases, DNA-PKcs (Ser-2056) which participates in repair of double strand breaks by non-homologous end-joining, and ATR (Ser-428) which senses stalled DNA replication forks. Fourth, we investigated the role of components of homologous recombination (HR) in CNDAG-induced DNA damage repair. The clonogenic survival of human fibroblasts deficient in ATM or those transfected with an empty vector were approximately 20- to 30-fold more sensitive to CNDAG prodrugs than cells complemented with full-length ATM cDNA. Chinese hamster cells deficient in Rad51D or either of the two Rad51-interacting proteins, Xrcc3 and Brca2, conferred greater than 30-fold sensitivity to CNDAG prodrugs relative to respective wild type lines. Similar sensitization was also observed with CNDAC. In contrast, cells lacking HR function were not more sensitive to ara-C or ara-G compared to their parental and complemented cells, indicating HR is a unique repair mechanism for 2`-C-cyano-2`-deoxy-nucleoside analogues. Finally, a cytogenetic approach was used to analyze sister chromatid exchange (SCE, a hallmark for HR) formation in metaphase cells exposed to 2 microM CNDAG 6-NH2. The frequencies of SCEs in AA8 cells incubated with CNDAG for two cell cycles (mean 14.2 per metaphase) were 2-fold of those exposed for one cell cycle (mean 7.4 per metaphase, n>20, p<0.001), the latter greater than control (mean 6 per metaphase, p<0.05). Together these results demonstrate that DNA damage caused by CNDAG activates ATM-dependent signaling pathways and is repaired through homologous recombination. Thus, this is a class effect caused by 2`-C-cyano-2`-deoxy-nucleoside analogues. Our study suggests that despite relatively less potency, CNDAG might have distinct clinical activity from that of CNDAC. [1] Liu X, et al. Blood, Blood. 2010 May 17, Epub ahead of print, PMID: 20479284. Disclosures: No relevant conflicts of interest to declare.
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Gagnon, J., et G. J. Arlaud. « Primary structure of the A chain of human complement-classical-pathway enzyme C1r. N-terminal sequences and alignment of autolytic fragments and CNBr-cleavage peptides ». Biochemical Journal 225, no 1 (1 janvier 1985) : 135–42. http://dx.doi.org/10.1042/bj2250135.
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Activated human complement-classical-pathway enzyme C1r has previously been shown to undergo autolytic cleavages occurring in the A chain [Arlaud, Villiers, Chesne & Colomb (1980) Biochim. Biophys. Acta 616, 116-129]. Chemical analysis of the autolytic products confirms that the A chain undergoes two major cleavages, generating three fragments, which have now been isolated and characterized. The N-terminal alpha fragment (approx. 210 residues long) has a blocked N-terminus, as does the whole A chain, whereas N-terminal sequences of fragments beta and gamma (approx. 66 and 176 residues long respectively) do not, and their N-terminal sequences were determined. Fragments alpha, beta and gamma, which are not interconnected by disulphide bridges, are located in this order within C1r A chain. Fragment gamma is disulphide-linked to the B chain of C1r, which is C-terminal in the single polypeptide chain of precursor C1r. CNBr cleavage of C1r A chain yields seven major peptides, CN1b, CN4a, CN2a, CN1a, CN3, CN4b and CN2b, which were positioned in that order, on the basis of N-terminal sequences of the methionine-containing peptides generated from tryptic cleavage of the succinylated (3-carboxypropionylated) C1r A chain. About 60% of the sequence of C1r A chain (440-460 residues long) was determined, including the complete sequence of the C-terminal 95 residues. This region shows homology with the corresponding parts of plasminogen and chymotrypsinogen and, more surprisingly, with the alpha 1 chain of human haptoglobin 1-1, a serine proteinase homologue.
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Liu, C. P., F. H. Bach et S. K. Wu. « Molecular studies of a rare DR2/LD-5a/DQw3 HLA class II haplotype. Multiple genetic mechanisms in the generation of polymorphic HLA class II genes. » Journal of Immunology 140, no 10 (15 mai 1988) : 3631–39. http://dx.doi.org/10.4049/jimmunol.140.10.3631.
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Abstract A cDNA library was constructed from a homozygous B lymphoblastoid cell line (REM) obtained from an individual of a long isolated American Indian tribe, the Warao. The REM cell line expresses serologically defined determinants, DR2 and DQw3, and the T lymphocyte-defined (Dw/LD) specificity, LD-5a. T cells can recognize differences between FJO (a DR2/DQw1 cell line that expresses the Dw specificity MN2) and REM for both DR and DQ molecules. cNDA clones encoding the polymorphic DR beta 1-, DR beta 2-, DQ beta-, and DQ alpha-chains were sequenced and compared with other DR and DQ gene sequences. The DR beta 1-sequence of REM is identical to the DR beta 1-sequence of FJO; the DR beta 2-sequence is also identical to that of FJO except for one amino acid difference at position 67 in the polymorphic first domain (Leu in REM, Phe in FJO) due to a single point mutation. The DQ beta-sequence is identical to that of DR4/DQw3 haplotype; the DQ alpha is different from the DQ alpha of DR4/DQw3 haplotype and identical to the DQ alpha of both the DR3/DQw2 haplotype of a Raji cell line and the DR5/DQw3 haplotype in deduced amino acid sequence. Taken together, these findings suggest that: 1) a single amino acid difference (position 67) in the third hypervariable region of the first domain of the DR beta 2-chain in the DR2 haplotype is apparently sufficient for stimulating T cell responses; 2) the DQw3 serologic specificity may be defined mainly by the DQ beta-rather than DQ alpha-chain; and 3) multiple genetic events have probably occurred to generate the rarely found REM (DR2/LD-5a/DQw3) haplotype.
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Zawada-Michałowska, Magdalena, Paweł Pieśko et Jerzy Józwik. « Tribological Aspects of Cutting Tool Wear during the Turning of Stainless Steels ». Materials 13, no 1 (26 décembre 2019) : 123. http://dx.doi.org/10.3390/ma13010123.
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The research paper presents the tribological aspects of cutting tool wear during the turning of stainless steels. An experiment was conducted in order to assess the wear of carbide cutting inserts with CVD-applied anti-wear coatings (CNMG 12 04 08 ZSZ and CNMA 12 04 12-KR 3205) and an uncoated ceramic cutting insert (CNGA 12 04 08 T0102 WG 650). The test subject included the following stainless steel grades X20Cr13 (1.4021) and X8CrNiS18-9 (1.4305). The analysis involved the direct wear indicator, VBBmax, and the indirect wear indicator, which was the roughness of machined surfaces and the Ra parameter. Based on the obtained results for both X20Cr13 and X8CrNiS18-9 steels, it was noticed that the best durability was exhibited by the CNMG 12 04 08 ZSZ insert, whereas the worst durability was identified for the CNGA 12 04 08 T0102 WG 650 insert. When analysing the results obtained with the VBBmax direct indicator, it was observed that in the case of each of the insert, most often the course of their wear was of nature similar to linear. Comparing the VBBmax direct indicator with the indirect indicator, namely, the measured Ra parameter, it was concluded that they were convergent. Upon the deterioration of the surface quality, greater values of the selected geometric measure of wear on the flank face were also identified.
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Li, Wenli, Ju Tang, Yuzhao Li, Han Bai, Weizuo Zhang, Jin Zhang, Yiming Xiao et Wen Xu. « Preparation and Fluorescent Wavelength Control of Multi-Color Nitrogen-Doped Carbon Nano-Dots ». Nanomaterials 11, no 12 (25 novembre 2021) : 3190. http://dx.doi.org/10.3390/nano11123190.
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It is known that, by taking advantage of heteroatom doping, the electronic states and transition channels in carbon nano-dots (CNDs) can be effectively modulated. Thus, the photoluminescence (PL) properties of CNDs can be changed. For potential applications of CNDs as advanced materials for optoelectronic devices, it is important and significant to develop the practical techniques for doping heteroatoms into CNDs. In this work, we synthesize the multi-color fluorescent by using a fast and effective microwave method where the CNDs are nitrogen-doped. We examine the influence of different ratios of the raw materials on the structure and optical properties of N-CNDs. The results show that the prepared N-CNDs can generate blue (445 nm), green (546 nm), and orange (617 nm) fluorescence or PL with the mass ratio of the raw materials at 1:1, 1:2 and 1:3, respectively. We find that the N content in N-CNDs leads to different surface/edge states in n−π∗ domain. Thus, the wavelength of the PL emission from N-CNDs can be tuned via controlling the N concentration doped into the CNDs. Moreover, it is shown that the intensity of the PL from N-CNDs is mainly positively related to the content of C-O groups attached on the surface/edges of the N-CNDs. This study provides an effective experimental method and technical way to improve the fluorescent emission, and to modulate the color of the PL emission from CNDs.
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Ataie, Zomorrod, Mohammad Dastjerdi, Khadijeh Farrokhfall et Zahra Ghiravani. « The Effect of Cinnamaldehyde on iNOS Activity and NO-Induced Islet Insulin Secretion in High-Fat-Diet Rats ». Evidence-Based Complementary and Alternative Medicine 2021 (13 juillet 2021) : 1–8. http://dx.doi.org/10.1155/2021/9970678.
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Introduction. Obesity and insulin resistance are associated with alterations in nitric oxide level and insulin secretion. Previous studies demonstrated that cinnamaldehyde (CNMA) improved islet insulin secretion and restored nitric oxide (NO) level, but its underlying mechanisms have not been investigated. This study aimed to investigate the effect of CNMA on inducible nitric oxide synthase (iNOS) activity and NO-induced islet insulin secretion in high-fat-diet (HFD) treated rats. Materials and Methods. Forty male Wistar rats (12 weeks old) were randomly divided into four equal groups, namely, control, CNMA, HFD, and HFD + CNMA. Control and CNMA groups were treated with standard laboratory animals’ diet, while HFD and HDF + CNMA groups were fed with an HFD diet enriched with 25% W / W tail fat for 16 weeks. CNMA was administrated orally (20 mg/kg body weight, daily) during the study period. Islet insulin secretion and the inducible NOS activity in the presence or absence of L-NAME (NO synthase inhibitor, 5 mmol/L) were evaluated. Results. L-NAME-suppressed insulin secretion in control, HFD, and HFD + CNMA groups; however, in the CNMA group, it could not exhibit such effect ( P < 0.01 ). Islets of HFD-treated animals showed significantly higher iNOS activity than controls. CNMA treatment significantly suppressed iNOS activities in CNMA and HFD + CNMA groups compared with control and HFD, respectively. Conclusion. These results suggest that the beneficial effect of CNMA on insulin secretion might be due to its inhibitory effect on iNOS activity.
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Khan, Safeera, Jessica Chavez, Xuewei Zhu, Norman H. L. Chiu, Wendi Zhang, Ziyu Yin, Jian Han et al. « Carbon Nanodots Inhibit Oxidized Low Density Lipoprotein-Induced Injury and Monocyte Adhesion to Endothelial Cells Through Scavenging Reactive Oxygen Species ». Journal of Biomedical Nanotechnology 17, no 8 (1 août 2021) : 1654–67. http://dx.doi.org/10.1166/jbn.2021.3125.
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Oxidized low density lipoprotein (Ox-LDL) is a known biomarker of inflammation and atherosclerosis, a leading cause of death worldwide. As a new class of nanomaterials, carbon nanodots (CNDs) are widely used in bioimaging, diagnostics, and drug delivery. However, there is no current report on how these CNDs affect the cardiovascular system, particularly their potential in mediating endothelial inflammatory dysfunction. This study examined effects of CNDs on Ox-LDL-mediated endothelial dysfunction. CNDs significantly inhibited Ox-LDL-mediated adhesion of monocytes to human microvascular endothelial cells (HMEC-1), in human microvascular endothelial cells (HMEC-1). CNDs significantly inhibited Ox-LDL-mediated adhesion of monocytes to endothelial cells, which is an essential step in the development of atherosclerosis. Further, CNDs significantly inhibited OxLDL-induced expression of interleukin-8 (IL-8), a vital cytokine on monocyte adhesion to the endothelial cells. These results demonstrate CNDs possess anti-inflammatory properties. CNDs also protect cells against Ox-LDL-induced cytotoxicity. Electron paramagnetic resonance (EPR) spectroscopy studies demonstrated direct reactive oxygen species-scavenging by CNDs. This result indicates that the anti-inflammatory properties of CNDs are most likely due to their direct scavenging of reactive oxygen species. Animal studies involving mice did not show any morphological or physical changes between the CNDs and control groups. Our study provides evidence of potential of CNDs in reducing Ox-LDL-mediated inflammation and cytotoxicity in HMEC-1.
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Xu, Yaochang, et Ping Guo. « MEA-CNDP : A Membrane Evolutionary Algorithm for Solving Biobjective Critical Node Detection Problem ». Computational Intelligence and Neuroscience 2021 (28 novembre 2021) : 1–20. http://dx.doi.org/10.1155/2021/8406864.
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The critical node detection problem (CNDP) refers to the identification of one or more nodes that have a significant impact on the entire complex network according to the importance of each node in a complex network. Most methods consider the CNDP as a single-objective optimization problem, which requires more prior knowledge to a certain extent. This paper proposes a membrane evolution algorithm MEA-CNDP to solve biobjective CNDP. MEA-CNDP includes a population initialization strategy based on the evaluation of decision variables, a strategy to transform the main objective, a strategy to update the membrane inherited pool, and four membrane evolutionary operators. The numerical experiments on 16 benchmark problems with random and logarithmic weights show that MEA-CNDP outperforms other algorithms in most cases. In particular, MEA-CNDP has unique advantages in dealing with large-scale sparse bi-CNDP.
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Yang, Xue-Chun, Song Gao, Sha-Qi Fu, Xuan Yao, Zheng Jiao, Jing-Tai Zhao, Zhi-Jun Zhang et Ling-Li Cheng. « Aerogel Assembled by Two Types of Carbon Nanoparticles for Efficient Removal of Heavy Metal Ions ». Gels 8, no 8 (22 juillet 2022) : 459. http://dx.doi.org/10.3390/gels8080459.
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Both sodium alginate and polyethyleneimine (PEI) have a good ability to adsorb heavy metal ions. PEI and sodium alginate were used as important precursors to synthesize positively charged carbon nanoparticles (p-CNDs) with hydroxyl and carboxyl, and negatively charged carbon nanoparticles (n-CNDs) with amino, respectively. The carbon nanoparticles (CNDs) aerogel with a large specific surface area and rich functional groups were constructed by self-assembled p-CNDs and n-CNDs via electrostatic attraction for adsorption of heavy metal ions in water. The results show that CNDs aerogel has good adsorption properties for Pb2+ (96%), Cu2+ (91%), Co2+ (86%), Ni2+ (82%), and Cd2+ (78%). Furthermore, the fluorescence emission intensity of CNDs aerogel will gradually decrease with the increase in the adsorption rate, indicating that it can detect the adsorption process synchronously. In addition, the cytotoxicity test reveals that CNDs have good biocompatibility and will not cause secondary damage to biological cells.
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Perli, Gabriel, Marco C. P. Soares, Thiago D. Cabral, Diego L. Bertuzzi, Julio R. Bartoli, Sébastien Livi, Jannick Duchet-Rumeau, Cristiano M. B. Cordeiro, Eric Fujiwara et Catia Ornelas. « Synthesis of Carbon Nanodots from Sugarcane Syrup, and Their Incorporation into a Hydrogel-Based Composite to Fabricate Innovative Fluorescent Microstructured Polymer Optical Fibers ». Gels 8, no 9 (1 septembre 2022) : 553. http://dx.doi.org/10.3390/gels8090553.
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Carbon nanodots (CNDs) are interesting materials due to their intrinsic fluorescence, electron-transfer properties, and low toxicity. Here, we report a sustainable, cheap, and scalable methodology to obtain CNDs from sugarcane syrup using a domestic microwave oven. The CNDs were characterized by infrared spectroscopy, dynamic light scattering, atomic force microscopy, absorption, and emission spectroscopies. The CNDs have 3 nm in diameter with low polydispersity and are fluorescent. A fluorescent hydrogel–CNDs composite was obtained using gelatin polypeptide as the polymeric matrix. The new hydrogel–CNDs composite was incorporated in the cavities of a double-clad optical fiber using an innovative approach that resulted in a microstructured polymer optical fiber with intrinsic fluorescence. This work shows a promising alternative for the fabrication of fluorescent materials since the CNDs synthesis is sustainable and environmentally friendly. These CNDs might substitute the rare-earth and other heavy metals of high cost and toxicity, which are usually incorporated in double-clad fibers for applications on lasers, amplifiers, and spectroscopy.
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Khan, Safeera, Andrew Dunphy, Mmesoma S. Anike, Sarah Belperain, Kamal Patel, Norman H. L. Chiu et Zhenquan Jia. « Recent Advances in Carbon Nanodots : A Promising Nanomaterial for Biomedical Applications ». International Journal of Molecular Sciences 22, no 13 (24 juin 2021) : 6786. http://dx.doi.org/10.3390/ijms22136786.
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Carbon nanodots (CNDs) are an emerging class of nanomaterials and have generated much interest in the field of biomedicine by way of unique properties, such as superior biocompatibility, stability, excellent photoluminescence, simple green synthesis, and easy surface modification. CNDs have been featured in a host of applications, including bioimaging, biosensing, and therapy. In this review, we summarize the latest research progress of CNDs and discuss key advances in our comprehension of CNDs and their potential as biomedical tools. We highlighted the recent developments in the understanding of the functional tailoring of CNDs by modifying dopants and surface molecules, which have yielded a deeper understanding of their antioxidant behavior and mechanisms of action. The increasing amount of in vitro research regarding CNDs has also spawned interest in in vivo practices. Chief among them, we discuss the emergence of research analyzing CNDs as useful therapeutic agents in various disease states. Each subject is debated with reflection on future studies that may further our grasp of CNDs.
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Nguyen, Duy-Khanh, Thanh-Son Le, Quang-Trung Le et Xuan-Dung Mai. « The roles of intermediate fluorophores on the optical properties of bottom-up synthesized carbon nanodots ». HPU2 Journal of Science : Natural Sciences and Technology 2, no 2 (31 août 2023) : 68–82. http://dx.doi.org/10.56764/hpu2.jos.2023.2.2.68-82.
Texte intégralRésumé :
Carbon nanodots (CNDs) are the latest nano-sized carbon materials having unique properties such as biocompatible, highly photoluminescent, and nontoxic which are suitable for diverse applications including lighting, sensing, bioimaging, and biochemical analyzing. CNDs could be synthesized by top-down methods in which graphite is fragmented into nano-sized graphene dots. Alternatively, CNDs could be formed by a bottom-up synthetic strategy where organic molecules are fused together via complex condensation and carbonization processes. Although a great number of organic molecules have been used successfully to prepare CNDs there are very few CNDs that exhibit the quantum size effects. The absorption and emission properties of bottom-up synthesized CNDs rely vastly on molecular-like fluorophores which are the intermediates formed during the fusion of molecular precursors and are incorporated into CNDs in the later states of carbonization processes. This review aims to demonstrate recent understandings on the formation of intermediate fluorophores and their contribution to the optical properties of CNDs
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Asif, Saleem, Eun-Gyeong Kim, Yoon-Hee Jang, Rahmatullah Jan, Nari Kim, Sajjad Asaf, Lubna, Muhammad Farooq et Kyung-Min Kim. « Identification of the OsCML4 Gene in Rice Related to Salt Stress Using QTL Analysis ». Plants 11, no 19 (21 septembre 2022) : 2467. http://dx.doi.org/10.3390/plants11192467.
Texte intégralRésumé :
Soil salinity is a major abiotic stress that causes disastrous losses in crop yields. To identify favorable alleles that enhance the salinity resistance of rice (Oryza sativa L.) crops, a set of 120 Cheongcheong Nagdong double haploid (CNDH) lines derived from a cross between the Indica variety Cheongcheong and the Japonica variety Nagdong were used. A total of 23 QTLs for 8 different traits related to salinity resistance on chromosomes 1–3 and 5–12 were identified at the seedling stage. A QTL related to the salt injury score (SIS), qSIS-3b, had an LOD score of six within the interval RM3525–RM15904 on chromosome 3, and a phenotypic variation of 31% was further examined for the candidate genes. Among all the CNDH populations, five resistant lines (CNDH 27, CNDH 34-1, CNDH 64, CNDH 78, and CNDH 112), five susceptible lines (CNDH 52-1, CNDH 67, CNDH 69, CNDH 109, and CNDH 110), and the parent lines Cheongcheong and Nagdong were selected for relative gene expression analysis. Among all the genes, two candidate genes were highly upregulated in resistant lines, including the auxin-responsive protein IAA13 (Os03g0742900) and the calmodulin-like protein 4 (Os03g0743500-1). The calmodulin-like protein 4 (Os03g0743500-1) showed a higher expression in all the resistant lines than in the susceptible lines and a high similarity with other species in sequence alignment and phylogenetic tree, and it also showed a protein–protein interaction with other important proteins. The genes identified in our study will provide new genetic resources for improving salt resistance in rice using molecular breeding strategies in the future.
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Zhang, Jun, Xiao Zhang, Zhiyuan Ren, Lun Yang, Yalu Tang, Yalin Ma, Yu Cui, Benling Gao et P. K. Chu. « Influence of photon reabsorption on the optical and catalytic properties of carbon nanodots/titanium oxide composites ». Applied Physics Letters 120, no 21 (23 mai 2022) : 213902. http://dx.doi.org/10.1063/5.0093878.
Texte intégralRésumé :
To enhance the optical and catalytic properties of TiO2, carbon nanodots (CNDs) are incorporated to prepare hybrid CNDs/TiO2 materials with different precursor concentrations and the photocatalytic characteristics are evaluated systematically. When the CNDs/TiO2 materials are excited optically, some high-energy photons are reabsorbed by those in the lower energy states, indicating that photon reabsorption of CNDs plays a key role. The results enrich our understanding of the optical and catalytic mechanisms and provide insight into the design of CNDs-based composites.
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Chatzimitakos, Theodoros G., Athanasia Kasouni, Anastassios Troganis, Ioannis Leonardos, Ioannis Tzovenis, Alexandros Ntzouvaras et Constantine Stalikas. « Carbon Nanodots Synthesized from Dunaliella salina as Sun Protection Filters ». C 6, no 4 (30 octobre 2020) : 69. http://dx.doi.org/10.3390/c6040069.
Texte intégralRésumé :
Carbon nanodots (CNDs) are more and more being exploited for various applications including biological ones. To this end, they have been thoroughly studied for their potential as antibacterial, wound healing, and bioimaging agents. In this study, we examined the sun protection properties of CNDs. Dunaliella salina was selected as a promising precursor for the synthesis of CNDs which were compared with those produced by citric acid, a widely used precursor for such materials. The CNDs were examined spectrophotometrically, and the sun protection factors were calculated. Additionally, in vitro experiments were carried out to evaluate their UV protection properties and to obtain better insight into whether CNDs are suitable to be used as filters for the development of new sunscreens. The results were conclusive that both CNDs possess favorable properties that potentiate their use for the development of sunscreens. However, the CNDs from Dunaliella salina were found to be superior to those derived from citric acid. Therefore, they can further be exploited as sun protection filters.
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Walsby, Elisabeth J., Chiara Ghiggi, Ruth H. Mackay, Simon R. Green, Steven Knapper et Alan K. Burnett. « 2′–Cyano–2′–Deoxyarabinofuranosylcytosine Is Active in Acute Myeloid Leukaemia and Acts in Synergy with Cytarabine. » Blood 114, no 22 (20 novembre 2009) : 4153. http://dx.doi.org/10.1182/blood.v114.22.4153.4153.
Texte intégralRésumé :
Abstract Abstract 4153 2′–Cyano–2′–deoxyarabinofuranosylcytosine (CNDAC) is the metabolic product of sapacitabine following hydrolysis of the palmitoyl sidechain from the pyrimidine analog primarily by plasma, gut and liver amidases. CNDAC is in turn phosphorylated into the active triphosphate form (CNDACTP) by deoxycytidine kinase (dCK). CNDACTP is incorporated into DNA resulting in single stranded DNA breaks during replication and inducing cell cycle arrest. Previously the cytotoxic effects of CNDAC have also been associated with intracellular accumulation of CNDAC triphosphate and chain termination. CNDAC and sapacitabine have overlapping cytotoxic effects. Acute myeloid leukaemia (AML) cell lines NB4 and HL-60 had an LD50 of 0.24μM (± 0.24) for CNDAC and 0.23μM (± 0.21) for cytarabine (AraC) following 24 hours treatment. Primary AML blasts isolated from patients at diagnosis (n = 15) had a higher mean LD50 (25.22μM ± 19.41) for CNDAC and AraC (8.09μM ± 8.93). This is thought to be due to the requirement of cells to be actively cycling in order to be susceptible to these agents. CNDAC induces apoptosis in NB4 and HL-60 cell lines with significant increases in the percentage of cells with increased Annexin V/propidium iodide staining at concentrations of 1.0μM and above (P < 0.04) and significant caspase-3 activation at concentrations of 0.1μM and above (P < 0.05). Treatment with CNDAC also results in a significant concentration-dependent accumulation in the G2 phase of the cell cycle after 24 hours in NB4 and HL-60 cells (P = 0.003 and 0.011 respectively). Synergy was observed in the AML cell lines when CNDAC was combined with AraC at a ratio of 2:1 The mean combination index for CNDAC and AraC was 0.67 (± 0.21). The activity of deoxycytidine kinase (dCK) was blocked by the addition of excess deoxycytidine, under these conditions the effects of CNDAC were abrogated (P < 0.05) in NB4 and HL-60 cells suggesting that CNDAC requires phosphorylation by dCK for its activation in the cells. The nucleoside transporters hENT 1 and 2 and hCNT3 transport a range of nucleoside analogues through the cell membrane into cells, the use of hENT inhibitors led to a 2.5 fold increase in the LD50 for CNDAC (P = 0.028) over 48 hours. This prolonged exposure to CNDAC could have resulted in some passive uptake of CNDAC into the cells potentially explaining why the agent retained some cell killing activity. Equivalent results have been obtained with dCK and hENT inhibitors in other cell lines indicating that there is a general requirement for these enzymes for CNDAC activity. Interestingly, when cells are treated with the parent drug sapacitabine in the presence of excess deoxycytidine the cytotoxicity is reduced, but when cells are treated in the presence of hENT inhibitors, sapacitabine's cytotoxicity is improved. This suggests that the presence of the palmitoyl side-chain allows membrane permeability even in the absence of the traditional nucleoside transporters. Disclosures: Green: Cyclacel Ltd: Employment.
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Ditting, Tilmann, Karl F. Hilgers, Karie E. Scrogin, Alexander Stetter, Peter Linz et Roland Veelken. « Mechanosensitive cardiac C-fiber response to changes in left ventricular filling, coronary perfusion pressure, hemorrhage, and volume expansion in rats ». American Journal of Physiology-Heart and Circulatory Physiology 288, no 2 (février 2005) : H541—H552. http://dx.doi.org/10.1152/ajpheart.00131.2004.
Texte intégralRésumé :
Left ventricular (LV) end-diastolic pressure (LVEDP) increase due to volume expansion (VExp) enhances mechanosensitive vagal cardiac afferent C-fiber activity (CNFA), thus decreasing renal sympathetic nerve activity (RSNA). Hypotensive hemorrhage (hHem) attenuates RSNA despite decreased LVEDP. We hypothesized that CNFA increases with any change in LVEDP. Coronary perfusion pressure (CPP), supposedly affected in both conditions, might also be a stimulus of CNFA. VExp and hHem were performed in anesthetized male Sprague-Dawley rats while blood pressure, heart rate, and RSNA were measured. Cervical vagotomy abolished RSNA response in both reflex responses. Single-unit CNFA was recorded while LVEDP was changed. Rapid changes (± 4, ±6, ±8 mmHg) were obtained by graded occlusion of the caval vein and descending aorta. Prolonged changes were obtained by VExp and hHem. Furthermore, CNFA was recorded in a modified Langendorff heart while CPP was changed (70, 100, 40 mmHg). Rapid LVEDP changes increased CNFA [caval vein occlusion: +16 ± 3 Hz (approximately +602%); aortic occlusion: +15 ± 3 Hz (approximately +553%); 70 units; P < 0.05]. VExp and hHem ( n = 6) increased CNFA [VExp: +10 ± 4 Hz (approximately +1,033%); hHem: +10 ± 2 Hz (approximately +1,225%); P < 0.05]. An increase in CPP increased CNFA [+2 ± 1 Hz (approximately +225%); P < 0.05], whereas a decrease in CPP decreased CNFA [−0.8 ± 0.4 Hz (approximately −50%); P < 0.05]. All C fibers recorded originated from the LV. CNFA increased with any LVEDP change but changed equidirectionally with CPP. Thus neither LVEDP nor CPP fully accounts directly for afferent C-fiber and reflex sympathetic responses. The intrinsic afferent stimuli and receptive fields accounting for reflex sympathoinhibition still remain cryptic.
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Porcelli, Brunetta, Miriana d’Alessandro, Latika Gupta, Silvia Grazzini, Nila Volpi, Maria Romana Bacarelli, Federica Ginanneschi et al. « Anti-Cytosolic 5′-Nucleotidase 1A in the Diagnosis of Patients with Suspected Idiopathic Inflammatory Myopathies : An Italian Real-Life, Single-Centre Retrospective Study ». Biomedicines 11, no 7 (12 juillet 2023) : 1963. http://dx.doi.org/10.3390/biomedicines11071963.
Texte intégralRésumé :
Background: Anti-cytosolic 5′-nucleotidase 1A (anti-cN1A) antibodies were proposed as a biomarker for the diagnosis of inclusion body myositis (IBM), but conflicting specificity and sensitivity evidence limits its use. Our study aimed to assess the diagnostic accuracy of anti-cN1A in a cohort of patients who underwent a myositis line immunoassay for suspected idiopathic inflammatory myopathies (IIM). We also assessed the agreement between two testing procedures: line immunoassay (LIA) and enzyme-linked immunoassay (ELISA). Materials and methods: We collected retrospective clinical and serological data for 340 patients who underwent a myositis antibody assay using LIA (EUROLINE Autoimmune Inflammatory Myopathies 16 Ag et cN-1A (IgG) line immunoassay) and verification with an anti-cN1A antibody assay using ELISA (IgG) (Euroimmun Lubeck, Germany). Results: The serum samples of 20 (5.88%) patients (15 females, 5 males, mean age 58.76 ± 18.31) tested positive for anti-cN1A using LIA, but only two out of twenty were diagnosed with IBM. Seventeen out of twenty tested positive for anti-cN1A using ELISA (median IQR, 2.9 (1.9–4.18)). Conclusions: Our study suggests excellent concordance between LIA and ELISA for detecting anti-cN1A antibodies. LIA may be a rapid and useful adjunct, and it could even replace ELISA for cN1A assay. However, the high prevalence of diseases other than IBM in our cohort of anti-cN1A-positive patients did not allow us to consider anti-cN1A antibodies as a specific biomarker for IBM.
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Gotangco Castillo, C. Kendra, Samuel Levis et Peter Thornton. « Evaluation of the New CNDV Option of the Community Land Model : Effects of Dynamic Vegetation and Interactive Nitrogen on CLM4 Means and Variability ». Journal of Climate 25, no 11 (juin 2012) : 3702–14. http://dx.doi.org/10.1175/jcli-d-11-00372.1.
Texte intégralRésumé :
The Community Land Model, version 4 (CLM4) includes the option to run the prognostic carbon–nitrogen (CN) model with dynamic vegetation (CNDV). CNDV, which simulates unmanaged vegetation, modifies the CN framework to implement plant biogeography updates. CNDV simulates a reasonable present-day distribution of plant functional types but underestimates tundra vegetation cover. The CNDV simulation is compared against a CN simulation using a vegetation distribution generated by CNDV and against a carbon-only simulation with prescribed nitrogen limitation (CDV). The comparisons focus on the means and variability of carbon pools and fluxes and biophysical factors, such as albedo, surface radiation, and heat fluxes. The study assesses the relative importance of incorporating interactive nitrogen (CDV to CNDV) versus interactive biogeography (CN to CNDV) in present-day equilibrium simulations. None of the three configurations performs consistently better in simulating carbon or biophysical variables compared to observational estimates. The interactive nitrogen (N) cycle reduces annual means and interannual variability more than dynamic vegetation. Dynamic vegetation reduces seasonal variability in leaf area and, therefore, in moisture fluxes and surface albedo. The interactive N cycle has the opposite effect of enhancing seasonal variability in moisture fluxes and albedo. CNDV contains greater degrees of freedom than CN or CDV by adjusting both through nitrogen–carbon interactions and through vegetation establishment and mortality. Thus, in these equilibrium simulations, CNDV acts as a stronger “regulator” of variability compared to the other configurations. Discussed are plausible explanations for this behavior, which has been shown in past studies to improve climate simulations through better represented climate–vegetation interactions.
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Kishore, Somasundaram Chandra, Suguna Perumal, Raji Atchudan, Thomas Nesakumar Jebakumar Immanuel Edison, Ashok K. Sundramoorthy, Muthulakshmi Alagan, Sambasivam Sangaraju et Yong Rok Lee. « Eco-Friendly Synthesis of Functionalized Carbon Nanodots from Cashew Nut Skin Waste for Bioimaging ». Catalysts 13, no 3 (9 mars 2023) : 547. http://dx.doi.org/10.3390/catal13030547.
Texte intégralRésumé :
In this study, Anacardium occidentale (A. occidentale) nut skin waste (cashew nut skin waste) was used as a raw material to synthesize functionalized carbon nanodots (F-CNDs). A. occidentale biomass-derived F-CNDs were synthesized at a low temperature (200 °C) using a facile, economical hydrothermal method and subjected to XRD, FESEM, TEM, HRTEM, XPS, Raman Spectroscopy, ATR-FTIR, and Ultraviolet-visible (UV–vis) absorption and fluorescence spectroscopy to determine their structures, chemical compositions, and optical properties. The analysis revealed that dispersed, hydrophilic F-CNDs had a mean diameter of 2.5 nm. XPS and ATR-FTIR showed F-CNDs had a crystalline core and an amorphous surface decorated with –NH2, –COOH, and C=O. In addition, F-CNDs had a quantum yield of 15.5% and exhibited fluorescence with maximum emission at 406 nm when excited at 340 nm. Human colon cancer (HCT-116) cell assays showed that F-CNDs readily penetrated into the cells, had outstanding biocompatibility, high photostability, and minimal toxicity. An MTT assay showed that the viability of HCT-116 cells incubated for 24 h in the presence of F-CNDs (200 μg mL–1) exceeded 95%. Furthermore, when stimulated by filters of three different wavelengths (405, 488, and 555 nm) under a laser scanning confocal microscope, HCT-116 cells containing F-CNDs emitted blue, red, and green, respectively, which suggests F-CNDs might be useful in the biomedical field. Thus, we describe the production of a fluorescent nanoprobe from cashew nut waste potentially suitable for bioimaging applications.
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Chavez, Jessica, Ajmal Khan, Kenna R. Watson, Safeera Khan, Yaru Si, Alexandra Y. Deng, Grant Koher, Mmesoma S. Anike, Xianwen Yi et Zhenquan Jia. « Carbon Nanodots Inhibit Tumor Necrosis Factor-α-Induced Endothelial Inflammation through Scavenging Hydrogen Peroxide and Upregulating Antioxidant Gene Expression in EA.hy926 Endothelial Cells ». Antioxidants 13, no 2 (10 février 2024) : 224. http://dx.doi.org/10.3390/antiox13020224.
Texte intégralRésumé :
Carbon nanodots (CNDs) are a new type of nanomaterial with a size of less than 10 nanometers and excellent biocompatibility, widely used in fields such as biological imaging, transmission, diagnosis, and drug delivery. However, its potential and mechanism to mediate endothelial inflammation have yet to be explored. Here, we report that the uptake of CNDs by EA.hy926 endothelial cells is both time and dose dependent. The concentration of CNDs used in this experiment was found to not affect cell viability. TNF-α is a known biomarker of vascular inflammation. Cells treated with CNDs for 24 h significantly inhibited TNF-α (0.5 ng/mL)-induced expression of intracellular adhesion molecule 1 (ICAM-1) and interleukin 8 (IL-8). ICAM-1 and IL-8 are two key molecules responsible for the activation and the firm adhesion of monocytes to activated endothelial cells for the initiation of atherosclerosis. ROS, such as hydrogen peroxide, play an important role in TNF-α-induced inflammation. Interestingly, we found that CNDs effectively scavenged H2O2 in a dose-dependent manner. CNDs treatment also increased the activity of the antioxidant enzyme NQO1 in EA.hy926 endothelial cells indicating the antioxidant properties of CNDs. These results suggest that the anti-inflammatory effects of CNDs may be due to the direct H2O2 scavenging properties of CNDs and the indirect upregulation of antioxidant enzyme NQO1 activity in endothelial cells. In conclusion, CND can inhibit TNF-α-induced endothelial inflammation, possibly due to its direct scavenging of H2O2 and the indirect upregulation of antioxidant enzyme NQO1 activity in endothelial cells.
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Liu, Xiaojun, Yaqing Wang, Sherri Benaissa, Akira Matsuda, Hagop Kantarjian, Zeev Estrov et William Plunkett. « Homologous recombination as a resistance mechanism to replication-induced double-strand breaks caused by the antileukemia agent CNDAC ». Blood 116, no 10 (9 septembre 2010) : 1737–46. http://dx.doi.org/10.1182/blood-2009-05-220376.
Texte intégralRésumé :
Abstract The nucleoside analog 2′-C-cyano-2′-deoxy-1-β-D-arabino-pentofuranosyl-cytosine (CNDAC), currently in clinical trials for hematologic malignancies, has a novel action mechanism of causing a single-strand break after its incorporation into DNA. Double-strand breaks (DSBs) are generated thereafter in vivo and, if not repaired, pose lethal impact on cell survival. This study sought to define the mechanisms by which CNDAC-induced DSBs are formed and repaired. We demonstrated that single-strand breaks induced by CNDAC incorporation into DNA were converted to DSBs when cells progressed into the subsequent S-phase. CNDAC-induced DSBs were products of replication, rather than a consequence of apoptosis. ATM, the activator of homologous recombination (HR), was essential for cell survival after CNDAC treatment in cell lines and in primary acute myeloid leukemia samples, as were the HR components, Rad51, Xrcc3, and Brca2. Furthermore, formation of sister chromatid exchanges, a hallmark of HR, increased significantly after CNDAC-treated cells had progressed into a second replication cycle. In contrast, neither the replication stress sensor ATR nor DNA-PK, the initiator of nonhomologous end-joining of DSB, was involved in repair of CNDAC-induced damage. Together, these results indicate that HR, but not nonhomologous end-joining, is the major repair or survival mechanism for DNA damage caused by CNDAC.
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Sekar, Rajkumar, Nagaraj Basavegowda, Saktishree Jena, Santhoshkumar Jayakodi, Pandian Elumalai, Amballa Chaitanyakumar, Prathap Somu et Kwang-Hyun Baek. « Recent Developments in Heteroatom/Metal-Doped Carbon Dot-Based Image-Guided Photodynamic Therapy for Cancer ». Pharmaceutics 14, no 9 (5 septembre 2022) : 1869. http://dx.doi.org/10.3390/pharmaceutics14091869.
Texte intégralRésumé :
Carbon nanodots (CNDs) are advanced nanomaterials with a size of 2–10 nm and are considered zero-dimensional carbonaceous materials. CNDs have received great attention in the area of cancer theranostics. The majority of review articles have shown the improvement of CNDs for use in cancer therapy and bioimaging applications. However, there is a minimal number of consolidated studies on the currently developed doped CNDs that are used in various ways in cancer therapies. Hence, in this review, we discuss the current developments in different types of heteroatom elements/metal ion-doped CNDs along with their preparations, physicochemical and biological properties, multimodal-imaging, and emerging applications in image-guided photodynamic therapies for cancer.
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Mukherjee, Anurag, et Suhrit Ghosh. « Core-Substituted Naphthalene-Diimides (cNDI) and Related Derivatives : Versatile Scaffold for Supramolecular Assembly and Functional Materials ». Organic Materials 03, no 03 (16 juin 2021) : 281–92. http://dx.doi.org/10.1055/a-1530-0476.
Texte intégralRésumé :
Naphthalene-diimide (NDI)-derived building blocks have been explored extensively for supramolecular assembly as they exhibit attractive photophysical properties, suitable for applications in organic optoelectronics. Core-substituted derivatives of the NDI chromophore (cNDI) differ significantly from the parent NDI dye in terms of optical and redox properties. Adequate molecular engineering opportunities and substitution-dependent tunable optoelectronic properties make cNDI derivatives highly promising candidates for supramolecular assembly and functional materials. This short review discusses recent development in the area of functional supramolecular assemblies based on cNDIs and related molecules.Table of contents1. Introduction2. General Supramolecular Assemblies of cNDI Derivatives3. cNDI-Based Chiral Supramolecular Assemblies and Functional Materials4. Controlled Supramolecular Polymerization with cNDI Derivatives5. Dimeric Naphthalimide-Based Building Blocks6. Conclusions and Outlook
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Gong, Yi, Yanbing Han, Fang Zhang, Mingyue Zhai, Xing Chen, Qiaoyin Long, Ziyuan Wang, Fuchun Chen et Jianwen Yang. « Color Tuning of Biomass-Derived Carbon Nanodots by Reaction Temperature Toward White Light-Emitting Diodes ». Nano 15, no 12 (18 novembre 2020) : 2050159. http://dx.doi.org/10.1142/s1793292020501593.
Texte intégralRésumé :
In this work, carbon nanodots (CNDs) were synthesized from extract of mango leaves. Sphere nanodots were formed rapidly by one-step microwave heating. The photoluminescence (PL) of the CNDs was found greatly dependent on the reaction temperature. The emission peak position of the CNDs changed from 550[Formula: see text]nm to 430[Formula: see text]nm when the heating temperature increased from 120[Formula: see text]C to 150[Formula: see text]C. Particularly, the CNDs synthesized at 130[Formula: see text]C showed multi-band emission at 411[Formula: see text]nm, 480[Formula: see text]nm and 530[Formula: see text]nm, providing emitting color from blue to yellow. Moreover, the free chlorophyll molecules in the solution added red fluorescence at 670[Formula: see text]nm, and the integrated emitting color of the CNDs solution was close to white. Coated on a commercial 365[Formula: see text]nm light-emitting diode (LED) chip, the CNDs showed greenish white light with CIE coordinates of (0.37, 0.44). This work provided a one-pot, rapid and green method to obtain multi-emissive CNDs toward white LEDs.
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Zhang, Junming, Ailing Yang et Kang Zhang. « Photophysical Properties of Bright Luminescent Polyethyleneimine@Carbon Nanodots and Their Application in White Light-Emitting Diodes ». Photonics 10, no 3 (2 mars 2023) : 262. http://dx.doi.org/10.3390/photonics10030262.
Texte intégralRésumé :
Highly fluorescent carbon nanodots (CNDs) have broad application prospects in optoelectronics, energy, biological imaging, and other fields because of their good solubility in water, adjustable photoluminescence (PL), low toxicity, good biocompatibility, and stable chemical properties. In this paper, polyethyleneimine@CNDs (PEI@CNDs) with unique excitation- and concentration-dependent PL properties were synthesized by one-pot hydrothermal approach. The morphology, structure, surface chemistry, photophysical properties, and stability of the PEI@CNDs were well probed. The PEI@CNDs solution at low concentration displayed blue PL with a quantum yield of 50.6%. As the concentrations of the PEI@CNDs increase, the PL colors changed from blue, cyan, and green, to greenish-yellow. At low concentration, the excitation-independent and excitation-dependent PL property is mainly caused by carbon core and surface state emission. However, at higher concentration, the quenched blue emission and enhanced green emission were found. This is mainly attributed to the aggregate-related inner filter effect, electron transfer, and surface states. Mixing 10.0 mg/mL of PEI@CNDs with polyvinyl alcohol can be used to construct composite films, which were combined with the blue light-emitting diode to construct white light-emitting diodes with white and warm white emissions.
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Gude, Venkatesh. « Synthesis of hydrophobic photoluminescent carbon nanodots by using L-tyrosine and citric acid through a thermal oxidation route ». Beilstein Journal of Nanotechnology 5 (11 septembre 2014) : 1513–22. http://dx.doi.org/10.3762/bjnano.5.164.
Texte intégralRésumé :
Hydrophobic photoluminescent carbon nanodots (CNDs) were fabricated by using citric acid and L-tyrosine precursor molecules through a simple, facile thermal oxidation process in air. These CNDs (less than 4 nm in size) exhibited a characteristic excitation wavelength dependent emission and upconversion emission properties and are insoluble in water, but soluble in organic solvents. FTIR and 1H NMR analyses showed a selective participation of L-tyrosine molecule during the carbonization process at 220 °C without a disturbance of its benzylic protons and aromatic phenyl ring bearing hydroxy group. TEM and XRD studies revealed a quasi-spherical morphology and poor-crystalline nature of CNDs. Because the presence of the hydroxy group of L-tyrosine is dominating at the surface, these CNDs are also soluble in water under basic conditions. The effects of base and silver nanoparticles on the luminescence properties of CNDs were studied and a quenching of fluorescence was observed. These tyrosine-passivated CNDs are applicable for both biologically and commercially.
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Sai, Liman, Shuping Jiao et Jianwen Yang. « Ultraviolet Carbon Nanodots Providing a Dual-Mode Spectral Matching Platform for Synergistic Enhancement of the Fluorescent Sensing ». Molecules 25, no 11 (9 juin 2020) : 2679. http://dx.doi.org/10.3390/molecules25112679.
Texte intégralRésumé :
The sensing of chromium(VI) (Cr(VI)) is highly desired, due to its toxic and carcinogenic effects upon human health. Fluorescent probes, especially carbon nanodots (CNDs), have been widely used for Cr(VI) sensing via the inner filter effect (IFE). However, improving the sensitivity of these probes remains a difficult issue. In this work, CNDs derived from β-Lactoglobulin were applied as an ultrasensitive fluorescent probe for Cr(VI). With 260 nm excitation, the CNDs showed multi-band emission, including an ultraviolet 360 nm peak. The spectral matching of the CNDs with Cr(VI) led to synergistic suppression of both the excitation and emission light in the fluorescent sensing. As a consequence, the CNDs showed high sensitivity toward Cr(VI), the detection limit reaching as low as 20 nM. Moreover, taking advantage of the multi-emissive property of the CNDs, the synergistic effect was proven in an IFE-based sensing system, which might be extended to the design of other kinds of fluorescent probes.
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Harsanti, S.Si, Lilik. « PERBAIKAN PEMULIAAN MUTASI PADA TANAMAN KAPAS (Gossypium hirsutum.L) ». Jurnal Ilmiah Aplikasi Isotop dan Radiasi 12, no 2 (9 juin 2017) : 123. http://dx.doi.org/10.17146/jair.2016.12.2.3225.
Texte intégralRésumé :
PERBAIKAN PADA TANAMAN KAPAS DENGAN PEMULIAAN MUTASI (Gossypium hirsutum.L). Kapas memiliki potensi yang besar untuk dibudidayakan dan dikembangkan di Indonesia karena memiliki daya adaptasi yang luas, produktivitas tinggi, efisien dalam penggunaan input perkebunan, relatif tahan terhadap hama dan penyakit tanaman. Secara umum tanaman kapas merupakan tanaman industri penghasil serat yang penting dalam industri bahan pakaian. Sentra penanaman kapas telah lama dikenal dan ditanam oleh petani khususnya di Jawa Timur, Jawa Tengah, NTB, Sulawesi selatan dan sulawesi tenggara biasanya ditanam setelah pemanenan padi sawah. Galur-galur mutan yang berasal dari kultur jaringan embrio aksis kapas varietas NIAB-999 yang diiradiasi gamma 60 Co, dengan dosis 20 gray digunakan dalam percobaan ini. Percobaan dilakukan di Kebun Percobaan Citayam menggunakan rancangan Acak Kelompok dengan ulangan 5 kali.Kedua galur ditanam pada plot yang berukuran 8 x 7 M2 dengan jarak tanam 10 x 100 cm dan menggunakan varietas: Kanesia 15, Karisma sebagai pembanding. Parameter yang diamati adalah umur tanaman, tinggi tanaman, jumlah cabang generatif, jumlah boll perpohon dan berat kapas per biji perpetak/produksi . Hasil penelitian menunjukkan bahwa tanaman galur mutan CN 2A merupakan hasil terbesar hasil berat kapas per biji perpetak perkilogram yaitu 6,300 kg jika dibandingkan dengan kontrol nasional (Kanesia 15 dan varietas Karisma) serta kontrol induk NIAB 999. Pengujian Mutu Serat di Balai Besar Tekstil Bandung Sedangkan untuk kekuatan serat CN4A (29,7 (g/tex) masih tinggi hasilnya dibandingkan dengan Karisma (29,7 g/tex) dan Kanesia 15 (29,00 g/tex). Untuk kehalusan serat CN4A (5,3 micron) dan yang terendah NIAB 999 (4,9 micron) masih unggul dari kontrol nasional Kanesia 15 (5,2 micron). Demikian juga dengan keseragaman serat yang tertinggi CN2A (8,6 %) sedang kontrol nasional Kanesia 15 (83,7%) keseragaman serat dari keempat jenis kapas yang diuji cukup baik yaitu di atas 80 %. Pengujian Penyakit di Hama Penyakit di BALITTAS Malang dengan uji hasil utk mortalitas larva Helicoverpa amigera setelah mengkonsumsi daun kuncup bunga dan daun buah muda yang Pada hari ketiga umumnya larva masih hidup100%, kecuali pada varietas Kanesia 15 terjadi kematian larva 8%. Pada hari ketujuh kematian larva 15-37% dan hari kesebelas kematian larva mencapai 39-57%. Mortalitas larva hari ketujuh dan kesebelas, tidak berbeda nyata pada semua galur harapan dan varietas kontrol nasional kanesia 15, Kanesia 10 dan Karisma.
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Indriyati, Muhammad Miftahul Munir, Muhamad Nasir et Ferry Iskandar. « Effect of post-treatment drying processes on the optical and photothermal properties of carbon nanodots derived via microwave-assisted method ». IOP Conference Series : Earth and Environmental Science 1017, no 1 (1 avril 2022) : 012009. http://dx.doi.org/10.1088/1755-1315/1017/1/012009.
Texte intégralRésumé :
Abstract Carbon nanodots (CNDs) are considered as potential materials for photothermal applications and can be used as solar absorbers to enhance the absorption and conversion efficiency of solar energy to heat. To meet the criteria as solar absorbers, CNDs were synthesized via microwave heating and dried by two different drying processes, namely freeze drying and oven drying, obtaining CNDs powder with the labeled of CND-FD and CND-OD, respectively. The effect of these two drying methods on the optical and photothermal properties of CNDs was investigated. It was observed that soft and light powders were obtained from freeze drying, while oven drying resulted in shiny and agglomerate particles. Oven drying did not alter the absorption profile of CNDs, but freeze-drying resulted in broader and slightly red-shift absorption compared with that of CNDs colloid before drying. Photoluminescence intensity of CND-FD was only half of that of CND-OD. FTIR analysis revealed that CND-FD contained fewer hydroxyl and hydrophilic amine groups, leading to less hygroscopic nature of CND-FD than CND-OD. Because of its better absorption capability, the presence of CND-FD in water significantly increased the water evaporation rate and evaporation efficiency up to 2.2 kg/m2.h and 84%, respectively, three times higher than that of water without CNDs. With a similar photothermal testing condition, CND-OD resulted in a evaporation rate of only 0.9 kg/m2.h and evaporation efficiency of 36%. It can be noticed that freeze drying is more suitable to dry CNDs powder over oven drying to obtain excellent optical and photothermal properties of CNDs.
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Indriyati, Muhammad Miftahul Munir, Muhamad Nasir et Ferry Iskandar. « Effect of post-treatment drying processes on the optical and photothermal properties of carbon nanodots derived via microwave-assisted method ». IOP Conference Series : Earth and Environmental Science 1017, no 1 (1 avril 2022) : 012009. http://dx.doi.org/10.1088/1755-1315/1017/1/012009.
Texte intégralRésumé :
Abstract Carbon nanodots (CNDs) are considered as potential materials for photothermal applications and can be used as solar absorbers to enhance the absorption and conversion efficiency of solar energy to heat. To meet the criteria as solar absorbers, CNDs were synthesized via microwave heating and dried by two different drying processes, namely freeze drying and oven drying, obtaining CNDs powder with the labeled of CND-FD and CND-OD, respectively. The effect of these two drying methods on the optical and photothermal properties of CNDs was investigated. It was observed that soft and light powders were obtained from freeze drying, while oven drying resulted in shiny and agglomerate particles. Oven drying did not alter the absorption profile of CNDs, but freeze-drying resulted in broader and slightly red-shift absorption compared with that of CNDs colloid before drying. Photoluminescence intensity of CND-FD was only half of that of CND-OD. FTIR analysis revealed that CND-FD contained fewer hydroxyl and hydrophilic amine groups, leading to less hygroscopic nature of CND-FD than CND-OD. Because of its better absorption capability, the presence of CND-FD in water significantly increased the water evaporation rate and evaporation efficiency up to 2.2 kg/m2.h and 84%, respectively, three times higher than that of water without CNDs. With a similar photothermal testing condition, CND-OD resulted in a evaporation rate of only 0.9 kg/m2.h and evaporation efficiency of 36%. It can be noticed that freeze drying is more suitable to dry CNDs powder over oven drying to obtain excellent optical and photothermal properties of CNDs.
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Lucchini, Matteo, Lorenzo Maggi, Elena Pegoraro, Massimiliano Filosto, Carmelo Rodolico, Giovanni Antonini, Matteo Garibaldi et al. « Anti-cN1A Antibodies Are Associated with More Severe Dysphagia in Sporadic Inclusion Body Myositis ». Cells 10, no 5 (10 mai 2021) : 1146. http://dx.doi.org/10.3390/cells10051146.
Texte intégralRésumé :
In recent years, an autoantibody directed against the 5′-citosolic nucleotidase1A (cN1A) was identified in the sera of sporadic inclusion body myositis (s-IBM) patients with widely variable sensitivity (33%–76%) and specificity (87%–100%). We assessed the sensitivity/specificity of anti-cN1A antibodies in an Italian cohort of s-IBM patients, searching for a potential correlation with clinical data. We collected clinical data and sera from 62 consecutive s-IBM patients and 62 other inflammatory myopathies patients. Testing for anti-cN1A antibodies was performed using a commercial ELISA. Anti-cN1A antibodies were detected in 23 s-IBM patients, resulting in a sensitivity of 37.1% with a specificity of 96.8%. Positive and negative predictive values were 92.0% and 60.6%, respectively. We did not find significant difference regarding demographic variables, nor quadriceps or finger flexor weakness. Nevertheless, we found that anti-cN1A-positive patients presented significantly lower scores in IBMFRS item 1 (swallowing, p = 0.045) and more frequently reported more severe swallowing problems, expressed as an IBMFRS item 1 score ≤ 2 (p < 0.001). We confirmed the low sensitivity and high specificity of anti-cN1A Ab in s-IBM patients with a high positive predictive value. The presence of anti-CN1A antibodies identified patients with a greater risk of more severe dysphagia.
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Semsey, Dávid, Duyen H. H. Nguyen, Gréta Törős, Arjun Muthu, Safa Labidi, Hassan El-Ramady, Áron Béni, Mahendra Rai et Prokisch József. « Analysis of Fluorescent Carbon Nanodot Formation during Pretzel Production ». Nanomaterials 14, no 13 (3 juillet 2024) : 1142. http://dx.doi.org/10.3390/nano14131142.
Texte intégralRésumé :
Baked pretzels are a popular choice for a quick snack, easily identifiable by their classic twisted shape, glossy exterior, and small salt crystals sprinkled on top, making them a standout snack. However, it is not commonly known that compounds with fluorescent properties can be formed during their production. Carbon nanodots (CNDs) with an average size of 3.5 nm were isolated and identified in bakery products. This study delved into the formation of CNDs in pretzel production using a fractional factorial experimental design. The research revealed that the baking temperature had the most significant impact on the concentration of CNDs, followed by the concentration of NaOH in the immersion solution, and then the baking time. This study highlights the unique role of the NaOH immersion step, which is not typically present in bread-making processes, in facilitating the formation of CNDs. This discovery highlights the strong correlation between the formation of CNDs and the heat treatment process. Monitoring and controlling these factors is crucial for regulating the concentration of CNDs in pretzel production and understanding nanoparticle formation in processed foods for food safety.
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Sam, Simanye, Soraya Phumzile Malinga et Nonhlangabezo Mabuba. « Carbon Nanodots Embedded on a Polyethersulfone Membrane for Cadmium(II) Removal from Water ». Membranes 11, no 2 (5 février 2021) : 114. http://dx.doi.org/10.3390/membranes11020114.
Texte intégralRésumé :
Cadmium(II) is a toxic heavy metal in aquatic systems. As a potential solution, green carbon nanodots (CNDs) were synthesized from oats and embedded on polyethersulfone membrane (PES) via phase inversion for the adsorption of Cd2+ from water. Characterization techniques for the CNDs and PES membranes were transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Raman spectroscopy, atomic force microscopy (AFM), contact angle and a pure water flux assessment system operated at 300 kPa. TEM results showed that the CNDs were well dispersed with a uniform shape and size (6.7 ± 2.8 nm). Raman spectroscopy revealed that the CNDs were embedded on the PES and the ID/IG ratio slightly increased, showing that the membranes maintained good structural integrity.The CNDs/PES proved to be more hydrophilic than PES. The glassy carbon electrode (GCE) in anodic stripping voltammetry (ASV) technique detected 99.78% Cd2+ removal by 0.5% CNDs/PES at optimum conditions: 30 min. contact time, at pH 5 and 0.5 ppm Cd2+ solution. The 0.5% CNDs/PES removed Cd(II) due to the hydroxyl group (-OH) and carboxyl group (-COO-) on the membrane composite. It was established that Cu2+ and Pb2+ have a significant interfering effect during the analysis of Cd2+ using GCE in ASV technique. The 0.5% CNDs/PES is recyclable because it removed above 95% of cd2+ in four cycles. In a spiked tap water sample, 58.38% of Cd2+ was sensed by GCE of which 95% was in agreement with the value obtained from inductively coupled plasma optical emission spectrometry (ICPOES).
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Dunphy, Andrew, Kamal Patel, Sarah Belperain, Aubrey Pennington, Norman Chiu, Ziyu Yin, Xuewei Zhu et al. « Modulation of Macrophage Polarization by Carbon Nanodots and Elucidation of Carbon Nanodot Uptake Routes in Macrophages ». Nanomaterials 11, no 5 (26 avril 2021) : 1116. http://dx.doi.org/10.3390/nano11051116.
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Atherosclerosis represents an ever-present global concern, as it is a leading cause of cardiovascular disease and an immense public welfare issue. Macrophages play a key role in the onset of the disease state and are popular targets in vascular research and therapeutic treatment. Carbon nanodots (CNDs) represent a type of carbon-based nanomaterial and have garnered attention in recent years for potential in biomedical applications. This investigation serves as a foremost attempt at characterizing the interplay between macrophages and CNDs. We have employed THP-1 monocyte-derived macrophages as our target cell line representing primary macrophages in the human body. Our results showcase that CNDs are non-toxic at a variety of doses. THP-1 monocytes were differentiated into macrophages by treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) and co-treatment with 0.1 mg/mL CNDs. This co-treatment significantly increased the expression of CD 206 and CD 68 (key receptors involved in phagocytosis) and increased the expression of CCL2 (a monocyte chemoattractant and pro-inflammatory cytokine). The phagocytic activity of THP-1 monocyte-derived macrophages co-treated with 0.1 mg/mL CNDs also showed a significant increase. Furthermore, this study also examined potential entrance routes of CNDs into macrophages. We have demonstrated an inhibition in the uptake of CNDs in macrophages treated with nocodazole (microtubule disruptor), N-phenylanthranilic acid (chloride channel blocker), and mercury chloride (aquaporin channel inhibitor). Collectively, this research provides evidence that CNDs cause functional changes in macrophages and indicates a variety of potential entrance routes.
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Barry, Kathryn E., et Stefan A. Schnitzer. « Are we missing the forest for the trees ? Conspecific negative density dependence in a temperate deciduous forest ». PLOS ONE 16, no 7 (15 juillet 2021) : e0245639. http://dx.doi.org/10.1371/journal.pone.0245639.
Texte intégralRésumé :
One of the central goals of ecology is to determine the mechanisms that enable coexistence among species. Evidence is accruing that conspecific negative density dependence (CNDD), the process by which plant seedlings are unable to survive in the area surrounding adults of their same species, is a major contributor to tree species coexistence. However, for CNDD to maintain community-level diversity, three conditions must be met. First, CNDD must maintain diversity for the majority of the woody plant community (rather than merely specific groups). Second, the pattern of repelled recruitment must increase in with plant size. Third, CNDD should extend to the majority of plant life history strategies. These three conditions are rarely tested simultaneously. In this study, we simultaneously test all three conditions in a woody plant community in a North American temperate forest. We examined whether understory and canopy woody species across height categories and dispersal syndromes were overdispersed–a spatial pattern indicative of CNDD–using spatial point pattern analysis across life history stages and strategies. We found that there was a strong signal of overdispersal at the community level. Across the whole community, larger individuals were more overdispersed than smaller individuals. The overdispersion of large individuals, however, was driven by canopy trees. By contrast, understory woody species were not overdispersed as adults. This finding indicates that the focus on trees for the vast majority of CNDD studies may have biased the perception of the prevalence of CNDD as a dominant mechanism that maintains community-level diversity when, according to our data, CNDD may be restricted largely to trees.
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Tyutrin A.A., Rakevich A. L. et Martynovich E.F. « The luminescence photostability of carbon nanodots synthesized by the plasma method from a glucose solution after UV radiation ». Technical Physics Letters 49, no 3 (2023) : 40. http://dx.doi.org/10.21883/tpl.2023.03.55683.19427.
Texte intégralRésumé :
Carbon nanodots (CNDs) were synthesized by the microplasma method using a glucose solution as a precursor. The photoluminescence of CNDs before and after UV irradiation was studied. The spectral and kinetic properties of the synthesized CNDs were studied using a MicroTime 200 confocal scanning luminescence microscope. It was experimentally demonstrated that the short component (tau1) of luminescence refers to C=O bonds on the CND surface. A significant decrease in the luminescence intensity of CNDs after UV irradiation due to a decrease in oxygen-containing groups on the surface of carbon dots was found. Keywords: Luminescence, carbon nanodots, photostability, time-correlated photon counting.
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Dang, Christa, Karra D. Harrington, Yen Ying Lim, David Ames, Jason Hassenstab, Simon M. Laws, Nawaf Yassi et al. « Superior Memory Reduces 8-year Risk of Mild Cognitive Impairment and Dementia But Not Amyloid β-Associated Cognitive Decline in Older Adults ». Archives of Clinical Neuropsychology 34, no 5 (1 octobre 2018) : 585–98. http://dx.doi.org/10.1093/arclin/acy078.
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Abstract Objective To prospectively examine 8-year risk of clinical disease progression to mild cognitive impairment (MCI)/dementia in older adults ≥60 with superior episodic memory (SuperAgers) compared to those cognitively normal for their age (CNFA). Additionally, to determine the extent to which SuperAgers were resilient to the negative effects of elevated amyloid-beta (Aβ+) on cognition. Method Participants were classified as SuperAgers based on episodic memory performance consistent with younger adults aged 30–44 and no impairment on non-memory tests (n = 179), and were matched with CNFA on age, sex, education, and follow-up time (n = 179). Subdistribution hazard models examined risk of clinical progression to MCI/dementia. Linear mixed models assessed the effect of Aβ on cognition over time. Results Prevalence of Aβ+ and APOE ε4 was equivalent between SuperAgers and CNFA. SuperAgers had 69%–73% reduced risk of clinical progression to MCI/dementia compared to CNFA (HR: 0.27–0.31, 95% CI: 0.11–0.73, p < .001). Aβ+ was associated with cognitive decline in verbal memory and executive function, regardless of SuperAger/CNFA classification. In the absence of Aβ+, equivalent age-related changes in cognition were observed between SuperAgers and CNFA. Conclusions SuperAgers displayed resilience against clinical progression to MCI/dementia compared to CNFA despite equivalent risk for Alzheimer’s disease (AD); however, SuperAgers had no greater protection from Aβ+ than CNFA. The deleterious effects of Aβ on cognition persist regardless of baseline cognitive ability. Thus, superior cognitive performance does not reflect resistance against the neuropathological processes associated with AD, and the observed resilience for SuperAgers may instead reflect neuropsychological criteria for cognitive impairment.