Добірка наукової літератури з теми "Active laser gla"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Active laser gla".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Статті в журналах з теми "Active laser gla"
1
Bakunina, Irina, Lubov Slepchenko, Stanislav Anastyuk, Vladimir Isakov, Galina Likhatskaya, Natalya Kim, Liudmila Tekutyeva, Oksana Son та Larissa Balabanova. "Characterization of Properties and Transglycosylation Abilities of Recombinant α-Galactosidase from Cold-Adapted Marine Bacterium Pseudoalteromonas KMM 701 and Its C494N and D451A Mutants". Marine Drugs 16, № 10 (24 вересня 2018): 349. http://dx.doi.org/10.3390/md16100349.
Повний текст джерелаАнотація:
A novel wild-type recombinant cold-active α-d-galactosidase (α-PsGal) from the cold-adapted marine bacterium Pseudoalteromonas sp. KMM 701, and its mutants D451A and C494N, were studied in terms of their structural, physicochemical, and catalytic properties. Homology models of the three-dimensional α-PsGal structure, its active center, and complexes with D-galactose were constructed for identification of functionally important amino acid residues in the active site of the enzyme, using the crystal structure of the α-galactosidase from Lactobacillus acidophilus as a template. The circular dichroism spectra of the wild α-PsGal and mutant C494N were approximately identical. The C494N mutation decreased the efficiency of retaining the affinity of the enzyme to standard p-nitrophenyl-α-galactopiranoside (pNP-α-Gal). Thin-layer chromatography, matrix-assisted laser desorption/ionization mass spectrometry, and nuclear magnetic resonance spectroscopy methods were used to identify transglycosylation products in reaction mixtures. α-PsGal possessed a narrow acceptor specificity. Fructose, xylose, fucose, and glucose were inactive as acceptors in the transglycosylation reaction. α-PsGal synthesized -α(1→6)- and -α(1→4)-linked galactobiosides from melibiose as well as -α(1→6)- and -α(1→3)-linked p-nitrophenyl-digalactosides (Gal2-pNP) from pNP-α-Gal. The D451A mutation in the active center completely inactivated the enzyme. However, the substitution of C494N discontinued the Gal-α(1→3)-Gal-pNP synthesis and increased the Gal-α(1→4)-Gal yield compared to Gal-α(1→6)-Gal-pNP.
2
Thalji, Nabil K., Lacramioara Ivanciu, Reema Jasuja, Sunita Patel-Hett, Joachim Fruebis, Debra Pittman, and Rodney M. Camire. "Zymogen-like FXa Is a Potent Bypassing Agent for Reversal of Direct FXa Inhibitors in Vivo." Blood 124, no. 21 (December 6, 2014): 582. http://dx.doi.org/10.1182/blood.v124.21.582.582.
Повний текст джерелаАнотація:
Abstract The pharmacokinetic challenges of warfarin therapy have led to the development of new oral anticoagulants (NOACs) that directly inhibit coagulation factor Xa (FXa). While these new drugs (including rivaroxaban and apixaban) have many benefits over warfarin, no approved strategy exists to reverse their anticoagulant effects in the event of life-threatening bleeding or emergent need for surgery. The most promising reversal strategy in clinical development is a catalytically inactive form of FXa (Gla-domainless FXaS195A, GD-FXaS195A) that binds the NOAC with high affinity to relieve inhibition of endogenous FXa. In principle, removing the inhibitor through molecular engagement is attractive, especially when administered before bleeding begins (e.g. pre-surgery), and there is in vivo evidence to support the efficacy of GD-FXaS195A as a pre-injury antidote for direct FXa inhibitors. However, since GD-FXaS195A is a scavenger of the inhibitor and not a pro-hemostatic agent, GD-FXaS195A may not be effective if given after a bleeding episode has begun. Moreover, its mechanism of action necessitates a 1:1 ratio of GD-FXaS195A to neutralize the inhibitor. Thus, high doses (hundreds of milligrams of protein) will likely be required in humans. We hypothesized that a pro-hemostatic bypassing agent might be able to reverse the effects of direct FXa inhibitors no matter when it is administered, and with high potency. To evaluate this, we used a variant of FXa (FXaI16L) that is more zymogen-like than wild-type (wt)-FXa. This "zymogen-like" variant has lower catalytic activity in in vitro assays compared to wt-FXa due to impaired active site maturation. It is also resistant to active site inhibitors including plasma protease inhibitors, resulting in an extension of its plasma half-life (>30 minutes vs ~1 minute for wt-FXa). Importantly, its activity is rescued upon binding to its cofactor FVa in vivo, and we have previously shown that FXaI16L bypasses the intrinsic pathway defect in hemophilic mice. Here we evaluated whether FXaI16L might also be able to bypass direct FXa inhibitors using in vitro thrombin generation assays (TGAs) and two in vivo injury models in mice, and directly compared FXaI16L to GD-FXaS195A. In TGA experiments, 500 nM rivaroxaban decreased peak thrombin generation to 23% of that observed in normal human plasma (NHP). This decreased thrombin generation could be reversed by the addition of 3 nM human (h)FXaI16L which normalized peak thrombin generation. In comparative studies, hFXaI16L was 300-fold more potent than GD-FXaS195A in TGA assays. These data highlight that differences in mechanism of action (pro-hemostatic vs. scavenger) will have a huge impact on amounts of protein needed to revive thrombin generation. This was further reflected in in vivo studies. In invivo experiments with wild-type mice using 7.5% FeCl3 to induce carotid artery thrombosis, 1 mg/kg rivaroxaban prevented formation of occlusive thrombi. 30 minutes after the initial FeCl3 injury to rivaroxaban-treated mice, infusion of 0.25 mg/kg murine (m)FXaI16L normalized the phenotype, causing rapid occlusion at the injury site within 5 minutes. In contrast, we did not observe carotid artery occlusion with administration of up to 25 mg/kg GD-FXaS195A 30 minutes after the injury to rivaroxaban-treated mice (Fig. 1). When both rivaroxaban and the reversal agent were given prior to the injury, both mFXaI16L (0.5 mg/kg) and GD-FXaS195A (25 mg/kg) were effective at reversing the inhibition. Furthermore, using intravital microscopy to examine thrombus formation at the site of laser injury to mouse cremasteric arterioles, we found that 1 mg/kg rivaroxaban completely abrogated fibrin deposition and substantially reduced platelet accumulation. Treatment with1 mg/kg mFXaI16L substantially increased platelet and fibrin deposition at the site of laser injury. Figure 1 Carotid occlusion time when the reversal agent was infused 30 minutes after the FeCl3 injury. Figure 1. Carotid occlusion time when the reversal agent was infused 30 minutes after the FeCl3 injury. Taken together, these data provide strong support for the in vivo efficacy and potency of FXaI16L as a potential pro-hemostatic bypass agent to reverse direct FXa inhibitors. The data also illustrate that antidotes like GD-FXaS195A may not be as effective as pro-hemostatic agents like FXaI16L following an injury, and we predict that effective reversal of NOACs will require a nuanced approach that uses an antidote or a bypassing agent depending on the clinical scenario. Disclosures Jasuja: Pfizer: Employment. Patel-Hett:Pfizer: Employment. Fruebis:Pfizer: Employment. Pittman:Pfizer: Employment. Camire:Pfizer: Consultancy, Patents & Royalties, Research Funding.
3
Cujic, Danica, Zanka Bojic-Trbojevic, Nikola Kolundzic, Toshihiko Kadoya, and Ljiljana Vicovac. "Molecular forms of galectin-1 from human placenta and trophoblast cells." Journal of the Serbian Chemical Society 80, no. 2 (2015): 159–69. http://dx.doi.org/10.2298/jsc140428091c.
Повний текст джерелаАнотація:
Galectin-1 (gal-1) is the best studied member of the galectin family of the human placenta assumed to play important roles in pregnancy. Standard isolation of gal-1 from human placenta using lactose extraction and affinity chromatography in the presence of a reducing agent, produced several known forms of gal-1, which were compared to the recombinant human gal-1 (rhgal-1) and oxidized recombinant human gal-1 (Ox-gal-1). Isolated placental gal-1 retained lectin binding activity, evidenced by hemagglutination and dot blot lectin assays. Characterization of the forms present by surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF MS), based on hydrophilic interactions or immunorecognition, provided a sensitive tool for detection of the fine differences among the diverse molecular forms. The forms detected included previously established biologically active oxidized gal-1 and reduced gal-1, as well as some other currently uncharacterized (less investigate forms.
4
Guo, Xiaofeng, Xiaoling Gao, Brendan T. Keenan, Jingxu Zhu, Dimitra Sarantopoulou, Jie Lian, Raymond J. Galante, Gregory R. Grant, and Allan I. Pack. "RNA-seq analysis of galaninergic neurons from ventrolateral preoptic nucleus identifies expression changes between sleep and wake." BMC Genomics 21, no. 1 (September 14, 2020). http://dx.doi.org/10.1186/s12864-020-07050-7.
Повний текст джерелаАнотація:
Abstract Background Previous studies show that galanin neurons in ventrolateral preoptic nucleus (VLPO-Gal) are essential for sleep regulation. Here, we explored the transcriptional regulation of the VLPO-Gal neurons in sleep by comparing their transcriptional responses between sleeping mice and those kept awake, sacrificed at the same diurnal time. Results RNA-sequencing (RNA-seq) analysis was performed on eGFP(+) galanin neurons isolated using laser captured microdissection (LCM) from VLPO. Expression of Gal was assessed in our LCM eGFP(+) neurons via real time qPCR and showed marked enrichment when compared to LCM eGFP(−) cells and to bulk VLPO samples. Gene set enrichment analysis utilizing data from a recent single-cell RNA-seq study of the preoptic area demonstrated that our VLPO-Gal samples were highly enriched with galanin-expressing inhibitory neurons, but not galanin-expressing excitatory neurons. A total of 263 genes were differentially expressed between sleep and wake in VLPO-Gal neurons. When comparing differentially expressed genes in VLPO-Gal neurons to differentially expressed genes in a wake-active neuronal region (the medial prefrontal cortex), evidence indicates that both systemic and cell-specific mechanisms contribute to the transcriptional regulation in VLPO-Gal neurons. In both wake-active and sleep-active neurons, ER stress pathways are activated by wake and cold-inducible RNA-binding proteins are activated by sleep. In contrast, expression of DNA repair genes is increased in VLPO-Gal during wakefulness, but increased in wake-active cells during sleep. Conclusion Our study identified transcriptomic responses of the galanin neurons in the ventrolateral preoptic nucleus during sleep and sleep deprivation. Data indicate that VLPO contains mainly sleep-active inhibitory galaninergic neurons. The VLPO galanin neurons show responses to sleep and wake similar to wake-active regions, indicating these responses, such as ER stress and cold-inducible RNA-binding proteins, are systemic affecting all neuronal populations. Region-specific differences in sleep/wake responses were also identified, in particular DNA repair. Our study expands knowledge about the transcriptional response of a distinct group of neurons essential for sleep.
5
USPENSKAYA, ELENA V., POLYNA А. ZABORKINA, EVGENIYA A. RYNDINA, TATYANA V. PLETENEVA, MARIYA A. MOROZOVA, ILAHA V. KAZIMOVA, and ANTON V. SYROESHKIN. "APPLICATION OF MATHEMATICAL MODELING AND PHYSICO-CHEMICAL ANALYSIS METHODS IN THE PREDICTION OF BIOLOGICAL ACTIVITY AND QUALITY CONTROL OF GOSSYPOL DERIVATIVES." International Journal of Applied Pharmaceutics, November 7, 2022, 120–26. http://dx.doi.org/10.22159/ijap.2022v14i6.46052.
Повний текст джерелаАнотація:
Objective: The purpose of this work was to evaluate in silico biological activity profiles of real and virtual molecular structures of gossypol derivatives and to develop methods of Physico-chemical analysis to control their quality. Methods: Substance of gossypol-acetic acid (GAA) and 14 virtual derivatives; PASS and ChemicDescript QSAR methods; low angle and dynamic laser light scattering (LALLS, DLS) methods; IR Spectroscopy–Cary 630 Fourier Transform IR Spectrometer, UV spectrometry–Cary-60 spectrophotometer, Optical microscopy (Altami BIO 2 microscope); Spirotox method for a sample’s biological activity. Results: A distance-based topological Balaban index (J) was successfully selected by ChemicDescript analysis; the Pa meaning by PASS Online program showed maximum (from 0.8 to 0.9) variations of antitumor and antiandrogenic and minimum of antiviral activities of GAA derivatives (Pa<0.5) despite the existing literature data. Microscopy and DLS methods demonstrated the values of high powder dispersion d=0.8 nm and weak stability of colloidal particles =-0.9 mV. According to UV data =42.4±0.8 (100 ml·g-1·cm-1) at λmax=380 nm. The LALLS method determined the GAA dissolution rate constant in ethanol: k=0.041±0.004 s-1. The calculated activation energy values of cell biosensor death process in 1 mmol solution of GAA in N,N-DMF: °bsEa=174.36±0.45 kJ·mol-1 in comparison with the solvent medium: °bsEa=213±1.55 kJ·mol-1 Conclusion: The developed approach of chemometric, laser and biotesting methods can be used for the identification of biologically active properties, as well as for qualitative analysis within the development of the standard for the pharmaceutical substance of natural polyphenols.
Тези доповідей конференцій з теми "Active laser gla"
1
Ackerson, Crey, Brent Ward, Kristen Kennedy, Chunli Dai, Peter C. Griffith, and Elizabeth Hoy. "ACTIVE LAYER DETACHMENT SLIDES, KLUANE RANGES, SOUTHWEST YUKON." In GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-369887.
Повний текст джерела
2
Levy, Joseph, and Logan Schmidt. "LINKING PERMAFROST AND ACTIVE LAYER SURFACE PROPERTIES TO THERMOKARST RISK." In GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-281548.
Повний текст джерела
3
Nichols, Floyd, Melissa A. Berke, Melissa A. Berke, Keith O'Connor, Keith O'Connor, Lori A. Ziolkowski, and Lori A. Ziolkowski. "DETERMINING MICROBIAL COMMUNITY SHIFTS WITH ALTITUDE FROM THE ACTIVE LAYER OF PERMAFROST REGIONS IN ALASKA." In 54th Annual GSA Northeastern Section Meeting - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019ne-328690.
Повний текст джерела
4
LECOMPTE, M. F. "PENETRATION OF FACTOR Xa INTO PHOSPHOLIPID LAYERS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643834.
Повний текст джерелаАнотація:
Negatively charged phospholipids (PL) at the platelet surface play a crucial role in the conversion of prothrombin into thrombin in the prothrombinase complex. Interactions of prothrombin and factor Xa (FXa) with PL are generally thought to occur through ionic interactions via Ca++ bridges. However we have shown by various independent approaches that prothrom bin (as well as FV and FVa) actually penetrates into the PL layer. We show that this is also the case, in the presence of Ca++ , for the other vitamin K-dependent, Gla-containing protein of the complex, FXa.Electrochemical surface measurements indicate a reversible increase in the capacitance of condensed PL monolayers (containing various concentrations of phosphatidylserine (PS)), upon interaction with bovine FXa (kindly provided by Dr. C.M. Jackson). Reduction of the FXa disulfide bridges at the contact of the electrode further demonstrates penetration Parallely, radioactive surface measurements allow to follow the adsorption of FXa which is quite reversible on PS gono-layers and to determine the association constant, 6.106 1/mol, very similar to the Ka of FX, obtained by various different techniques.Finally, penetration of FXa with PS containing PL vesicles was tested using the radiolabelled apolar probe (INA) which binds selectively to the lipid embedded domains of protein. FXa was radioactively labelled and the label preferentially found on the active site containing FXa heavy chain Moreover, interaction of FXa with PS vesicles decreases its Km for S 2222.Supported by grant INSERM n° 845016
5
McClung, A. J. W., G. P. Tandon, K. E. Goecke, and J. W. Baur. "Non-Contact Technique for Characterizing Full-Field Surface Deformation of Shape Memory Polymers." In ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3679.
Повний текст джерелаАнотація:
Thermally-actuated shape memory polymers (SMPs) typically display two phases separated by the glass transition temperature (Tg). At temperatures well below the Tg, the polymer exhibits a relatively high elastic modulus. Well above the Tg the elastic modulus drops by several orders of magnitude. In this high temperature region, SMP materials can achieve strain levels well above 100 %. The complex behavior of SMPs (stiffnesses dropping to the order of 1 GPa and extremely high strain levels) precludes the use of traditional strain gages and low-contact force extensometers. The present study presents a detailed expansion of state-of-the-art thermomechanical testing techniques used to characterize the material behavior of SMPs. An MTS environmental chamber with an observation window allows for non-contact optical measurements during testing. A laser extensometer is used for measurement and active control of axial strain. The upper limit on the strain rate capability of the laser extensometer is established. In addition, the photographic strain measurement method known as digital image correlation (DIC) is incorporated, allowing for full field measurement of axial and transverse strains of SMPs over a range of temperatures and strain rates. The strain measurements of the DIC and laser extensometer are compared to each other as well as to clip-on extensometers and strain gages. The comparisons provide insight into the limitations of the traditional strain measurement systems. A series of tensile tests are performed on a commercial SMP from 25 °C up to temperatures of 130 °C and strain levels above 100 %. The laser extensometer provides a robust method for controlling the strain in the gage section of the samples. In addition, results show that the full field measurements of both the axial and the transverse strain are essential for characterizing the constitutive response of SMPs at room and elevated temperatures.
6
Akhmediev, N. N., and J. M. Soto-Crespo. "Plethora of soliton-like pulses in passively mode-locked fiber lasers." In Nonlinear Guided Waves and Their Applications. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/nlgw.1996.sad.10.
Повний текст джерелаАнотація:
There is a great interest in soliton generation in actively and passively mode-locked fiber lasers [1, 2, 3, 4]. The mode-locked soliton fiber lasers can generate pulses with a wide range of durations, pulse powers, and repetition rates. Theoretical studies of the soliton fiber lasers are based on the complex Ginzburg-Landau (CGLE). Different forms of this have been used, including the cubic GLE [5], cubic CGLE with saturation [6, 7], quintic CGLE [8, 9, 10, 11, 12], and more complicated models. All these models (except the cubic CGLE without saturation) have solutions in the form of stable pulses. In this study we have found two new forms of pulse-like solutions which have been missed in previous works. In particular, we discover that besides the well-known solution in the form of bell-shaped pulse (plain pulse), and two other forms found in [13], the quintic CGLE has two additional branches of stable stationary solutions in the form of wide composite pulses with a dual-frequency spectrum. These two solutions can co-exist with known pulses but exist for a narrower range of value of the parameters.
7
Alozie, Ogechukwu, Yi-Guang Li, Pericles Pilidis, Yang Liu, Xin Wu, Xingchao Shong, Wencheng Ren, and Theodosios Korakianitis. "An Integrated Principal Component Analysis, Artificial Neural Network and Gas Path Analysis Approach for Multi-Component Fault Diagnostics of Gas Turbine Engines." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15740.
Повний текст джерелаАнотація:
Abstract Gas path diagnostics is a key aspect of the engine health monitoring (EHM) process that aims to detect, identify and predict engine component faults, using information from installed sensors, in order to guide maintenance action, maintain engine efficiency and prevent catastrophic failures. To achieve high prediction accuracies, current data-derived diagnostic models tend to be engine specific while the model-based methods are known to be time-consuming, especially for complex engine configurations. This paper proposes an integrated approach for accurate and accelerated isolation and prediction of multiple-degraded gas turbine component faults that comprises 3 steps — feature extraction using the Principal Component Analysis (PCA), machine learning classification with a multi-layer perceptron, artificial neural network (MLP-ANN) and model-based fault prediction via the non-linear Gas Path Analysis (GPA) technique. In this hybrid approach, the PCA first transforms the measurement fault signature into a fault-feature domain, which becomes an input to the multi-label ANN classifier used to isolate the potential faulty components. The non-linear GPA finally quantifies the magnitude of degradation that produced the recorded fault signature. Once trained and validated, the PCA-ANN model is deployed as part of the data processing mechanism prior to the actual GPA calculation. This method was assessed and validated using the thermodynamic performance model of a 2-shaft, high-bypass ratio, turbofan engine. For training and testing the PCA-ANN classifier, a total of 28,000 final samples for 14 measurement parameters, each averaged from 10 data points with Gaussian noise of zero mean and unit standard deviation, and implanted with single-, double- and triple-component fault cases of various magnitude, were generated by steady-state performance simulation of the engine model at its reference operating condition. Correlation analysis of this data set revealed the optimum sensor subset to be used for multi-component diagnostics. A quantitative analysis of the PCA-ANN fault isolation on the test set produced a classification accuracy of 96.6% and performed better on all metrics, compared to other multi-label classification algorithms. Finally, the proposed integrated approach achieved an average of 94.35% reduction in processing time, when compared to the conventional non-linear GPA by component-fault-cases (CFCs), while predicting implanted faults to the same accuracy.
8
Stassen, J. M., and D. Collen. "ON THE MECHANISM OF THE IN VIVO SYNERGISM BETWEEN TISSUE-TYPE PLASMINOGEN ACTIVATOR (t-PA) AND SINGLE CHAIN UROKINASE-TYPE PLASMINOGEN ACTIVATOR (scu-PA)." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643793.
Повний текст джерелаАнотація:
t-PA and scu-PA, in molar ratios between 1:4 and 4:1 do not act synergically in vitro (Thromb. Haemost. 56,35,1986) but display marked synergism in a rabbit model (Circulation 74, 838, 1986) and in man (Am. Heart J. 112, 1083, 1986). To investigate the mechanism of in vivo synergism in the rabbit model (J. Clin. Invest. 71, 368, 1983), t-PA and scu-PA were infused 1) simultaneously over 4 hrs, 2) t-PA over 1 hr, then 15 min later scu-PA over 2 hrs and 3) scu-PA over 1 hr, then 15 min later t-PA over 2 hrs.Significant synergism on thrombolysis is observed when t-PA and scu-PA are infused simultaneously or when t-PA is followed by scu-PA but not when scu-PA is followed by t-PA. These results suggest that low dose t-PA induces some plasminogen activation, sufficient to partially degrade fibrin, exposing COOH-terminal lysines with high affinity for plasminogen (Eur. J. Biochem. 140, 513, 1984). scu-PA might then activate surface-bound Glu-pla-minogen more efficiently.Sequential therapy with t-PA (or any other agent which "predigests" the thrombus), followed by scu-PA might constitute an alternative to simultaneous infusion of synergistic thrombolytic agents.
9
Lei, Shenghui, Ertugrul Kardemir, David McCloskey, John F. Donegan, and Ryan Enright. "Thermo-Mechanical Study of AlN Thin-Films As Heat Spreaders in III-V Photonic Devices." In ASME 2017 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2017 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/ipack2017-74184.
Повний текст джерелаАнотація:
Ridge-type hybrid III-V active waveguides on silicon-on-insulator (SOI) substrates demonstrate poor thermal performance due to several factors. One aspect of their typical design that leads to large thermal resistance is the use of polymer-based optical cladding around the waveguide. To address this issue, we have been exploring the use of deposited aluminium nitride (AlN) as an alternative optical cladding material. AlN is an excellent dielectric with optical properties making it suitable as a cladding around III-V waveguides. Crucially, this material can demonstrate thermal conductivities ∼100 times larger than current polymer cladding materials such as benzocyclobutene (BCB). Electro-thermo simulation results suggest that replacing BCB with AlN could reduce device thermal resistance by ∼2 times. However, our previous linear elastic mechanical modelling indicates that mismatched thermal expansion has the potential to cause mechanical tensile failure in the III-V waveguide when cooled from the processing temperature to room temperature if AlN is deposited in a neutral residual stress state. Here, to facilitate the design of encapsulated reliable hybrid semiconductor lasers, we extend our finite element, electro-thermo-mechanical model to include a residual stress in the deposited AlN. Using the Christensen criterion to define the maximum allowable stress in the device, our simulations indicate that there is a window of residual compressive stress in the AlN where mechanical failure may be avoided. To assess the feasibility of accessing this region of compressive residual stress while maintaining suitable thermal properties in the deposited AlN, we measure the thermal conductivity of AlN thin films (∼1.6 μm thick) deposited on silicon using a time-domain thermo reflectance (TDTR) setup. Stress measurements demonstrate compressive residual stresses ranging from ∼0 to −0.5 GPa. The TDTR measurement results reveal a similar thermal conductivity of ∼155 Wm−1K−1 over the entire range of compressive residual stress. These results strengthen the promise of encapsulating III-V active waveguides with AlN that simultaneously satisfy both thermal and mechanical requirements.
10
de Four, N. J., R. M. Bertina, and F. Havgrkate. "STIMULATION OF FIBRINOLYSIS BY ACTIVATED PROTEIN C (APC)." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642961.
Повний текст джерелаАнотація:
In 1960 Mammen and Seegers reported the discovery of a new protein (autoprothrombin II-A, APC) with both anticoagulant and profibrinolytic activity. They found that APC accelerated clot lysis in vitro and proposed that this was due to a reduction of plasmin - inhibitory activity. Many years later Comp et al (J Clin Inv 68: 1221) reported that the infusion of APC into dogs resulted in an increase in circulating plasminogen activator activity. This observation stimulated more extensive studies of the profibrinolytic effects of APC.In our laboratories we have studied the effect of human APC on clot lysis both in whole blood (human) and in a system of purified human proteins. In these systems 125I-labelled fibrinogen was incorporated in a clot formed after the addition of Jombin (complete clot formation within 5 min) and the subsequent lysis of this clot was followed by measuring the release of I-labelled fibrin degradation products (FDP) into the supernatant. Human t-PA was added to the system to achieve complete lysis of the clot within a few hours.When APC was added to citrated whole blood before clot formation, it was found to accelerate clot lysis in a dose dependent way. This effeg| was specific for APC and dependent on an intact active site, on the presence of protein S (the protein cofactor of APC) and Ca . The presence of APC did not influence the composition of the FDP formed, as analysed by means of SDS-polyacry-1 amide gel electroforesis, and its effect was found to be independent of the presence or absence of a.-antiplasmin.Subsequently we developped a clot lysis system using the purified human proteins of the fibrinolytic system: fibrinogen, FXIII, t-PA, PAI-1 (from human endothelial cells), glu-plasminogen and a -antiplasmin. In this system clot lysis was dependent on the concentrations of plasminogen, -antiplasmin, t-PA and PAI-1, but independent on the thrombin concentration and the presence or absence of phospholipids (purified from human brain). In the absence of PAI-1, no effect of APC on clot lysis was observed. However, in the presence of PAI-1, APC accelerated clot lysis. This effect was independent of the presence or absence of phospholipids and/or protein S and could be explained by the observation that APC can form a complex with PAI-1 (~ 95 kd) and under certain conditions even can convert active PAI-1 (~ 46 kd) into an inactive degradation product (~ 42 kd). However, complex formation is relatively slow anti high PAI-1 concentrations are needed to observe the reaction. The addition of protein S or phospholipids in the presence of Ca did not stimulate complex formation. Therefore, it seems highly unlikely that neutralization of PAI-1 by APC is responsible for the profibrinolytic effect of APC in the whole blood clot lysis.A completely different explanation for the profibrinolytic effect of APC was suggested by the observation that the addition of blood-platelets to the system of purified fibrinolytic components introduced a dependence of the clot lysis rate on the thrombin concentration (decrease in clot lysis at increasing thrombin concentration). This finding opened the possibility that APC stimulated fibrinolysis by reducing the effective thrombin concentration. Subsequent experiments using the whole blood clot lysis system revealed that in the presence of anti-FX antibodies clot lysis was no longer accelerated by APC, while the actual rate of clot lysis depended on the concentration of thrombin added.We like to propose, that in a blood clot lysis system APC most likely accelerates fibrinolysis by reducing the effective thrombin concentration; if at all, neutralization of PAI-1 may play only a minor role.