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1.
Richard E. Lyon Natallia Safronava James G. Quintiere Stanislav I. Stoliarov Richard N. Walters Sean Crowley 《火与材料》2014,38(2):264-278
Five material properties commonly used to describe the fire behavior of solids were evaluated as sole explanatory variables for four small‐scale fire tests with pass/fail outcomes by using a physically based probabilistic (phlogistic) burning model. The phlogistic model describes the likelihood of passing vertical Bunsen burner tests and a regulatory heat release rate test reasonably well over a wide range of material properties, as deduced from the correlation coefficient and mean deviation of the predicted and measured values. Of the thermal, combustion, and fire properties examined, the best predictors of the likelihood of passing the fire tests of this study were the heat of combustion of the sample, the heat release capacity, and the heat release parameter. The relative merits and drawbacks of qualitative (threshold) and quantitative (probabilistic) approaches to predicting fire test results using thermal and combustion properties are discussed. Published 2013. This article is a U.S. Government work and is in the public domain in the USA. 相似文献
2.
Improving Web Service Discovery with Usage Data 总被引:2,自引:0,他引:2
Service-oriented computing and Web services are becoming more popular, enabling organizations to use the Web as a market for selling their own services and consuming existing services from others. Nevertheless, the more services are available, the more difficult it becomes to find the most appropriate service for a specific application. Existing approaches to Web service discovery tend to address different information-processing styles. However, Web services have functional and nonfunctional characteristics that can be difficult to present and control. Service behavior and quality-of-service (QoS) parameters can vary over time, and new services can emerge in certain business areas. 相似文献
3.
Gas phase criteria for the onset of flaming combustion of solids in fires are used to locate a critical temperature Tcr in a nonisothermal analysis (TA) experiment that corresponds to the surface temperature of the solid at ignition in a fire test, Tign. This critical TA temperature occurs at low conversion of solid to gaseous fuel so it is independent of the heating rate in the test or the thermal decomposition reaction model. However, Tcr depends on the thermal properties of the polymer and the conditions of the fire test in which the gas phase criteria were measured. Nonisothermal analysis data in nitrogen and air were obtained for 20 polymers by thermogravimetric analysis and microscale combustion calorimetry. The critical temperatures Tcrs obtained from TA experiments compared favorably with analytic results for a simple polymer ignition model and finite element simulations and were in qualitative agreement with ignition temperatures measured in standardized fire tests. 相似文献
4.
Natallia V. Dubashynskaya Anton N. Bokatyi Anatoliy V. Dobrodumov Igor V. Kudryavtsev Andrey S. Trulioff Artem A. Rubinstein Arthur D. Aquino Yaroslav A. Dubrovskii Elena S. Knyazeva Elena V. Demyanova Yuliya A. Nashchekina Yury A. Skorik 《International journal of molecular sciences》2023,24(1)
The growth of microbial multidrug resistance is a problem in modern clinical medicine. Chemical modification of active pharmaceutical ingredients is an attractive strategy to improve their biopharmaceutical properties by increasing bioavailability and reducing drug toxicity. Conjugation of antimicrobial drugs with natural polysaccharides provides high efficiency of these systems due to targeted delivery, controlled drug release and reduced toxicity. This paper reports a two-step synthesis of colistin conjugates (CT) with succinyl chitosan (SucCS); first, we modified chitosan with succinyl anhydride to introduce a carboxyl function into the polymer molecule, which was then used for chemical grafting with amino groups of the peptide antibiotic CT using carbodiimide chemistry. The resulting polymeric delivery systems had a degree of substitution (DS) by CT of 3–8%, with conjugation efficiencies ranging from 54 to 100% and CT contents ranging from 130–318 μg/mg. The size of the obtained particles was 100–200 nm, and the ζ-potential varied from −22 to −28 mV. In vitro release studies at pH 7.4 demonstrated ultra-slow hydrolysis of amide bonds, with a CT release of 0.1–0.5% after 12 h; at pH 5.2, the hydrolysis rate slightly increased; however, it remained extremely low (1.5% of CT was released after 12 h). The antimicrobial activity of the conjugates depended on the DS. At DS 8%, the minimum inhibitory concentration (MIC) of the conjugate was equal to the MIC of native CT (1 µg/mL); at DS of 3 and 5%, the MIC increased 8-fold. In addition, the developed systems reduced CT nephrotoxicity by 20–60%; they also demonstrated the ability to reduce bacterial lipopolysaccharide-induced inflammation in vitro. Thus, these promising CT-SucCS conjugates are prospective for developing safe and effective nanoantibiotics. 相似文献
5.
Natallia V. Dubashynskaya Sergei V. Raik Yaroslav A. Dubrovskii Elena V. Demyanova Elena S. Shcherbakova Daria N. Poshina Anna Y. Shasherina Yuri A. Anufrikov Yury A. Skorik 《International journal of molecular sciences》2021,22(16)
Improving the therapeutic characteristics of antibiotics is an effective strategy for controlling the growth of multidrug-resistant Gram-negative microorganisms. The purpose of this study was to develop a colistin (CT) delivery system based on hyaluronic acid (HA) and the water-soluble cationic chitosan derivative, diethylaminoethyl chitosan (DEAECS). The CT delivery system was a polyelectrolyte complex (PEC) obtained by interpolymeric interactions between the HA polyanion and the DEAECS polycation, with simultaneous inclusion of positively charged CT molecules into the resulting complex. The developed PEC had a hydrodynamic diameter of 210–250 nm and a negative surface charge (ζ-potential = −19 mV); the encapsulation and loading efficiencies were 100 and 16.7%, respectively. The developed CT delivery systems were characterized by modified release (30–40% and 85–90% of CT released in 15 and 60 min, respectively) compared to pure CT (100% CT released in 15 min). In vitro experiments showed that the encapsulation of CT in polysaccharide carriers did not reduce its antimicrobial activity, as the minimum inhibitory concentrations against Pseudomonas aeruginosa of both encapsulated CT and pure CT were 1 μg/mL. 相似文献
6.
Here, successful realization of a variable multivariate optical element (VMOE) based on a transmissive liquid crystal (LC) panel is reported. In contrast to conventional multivariate optical elements (MOEs), a single VMOE is a dynamic system, allowing measurement of numerous analytes in different mixtures. Furthermore, VMOE has superior spectral resolution in comparison to a conventional MOE. It is demonstrated here that the system implemented in a Raman spectrometer predicts the concentration of each individual component in toluene-acetonitrile-cyclohexane mixtures with a prediction error of <6% (mass percentage). With a dedicated optical design of the setup, a prediction error smaller than 2% is expected to be feasible for the current chemical system. 相似文献
7.
It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer (LDV). 相似文献
8.
The sensitivity of the burning rate to variations in physical and chemical properties of synthetic polymers has been examined in order to understand the relative importance of the knowledge of these properties. The sensitivity analysis was performed using a numerical pyrolysis model called ThermaKin, which was employed to compute the rate of burning (expressed in terms of mass loss) of a one‐dimensional material object exposed to steady radiative heat. The results of the calculations indicate that the knowledge of decomposition reaction parameters (including the Arrhenius pre‐exponential factor, activation energy, heat, and char yield) is of key importance for prediction of the peak and average burning rates. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
9.
Natallia Barykina 《Planning Perspectives》2017,32(3):333-352
During the first Five-Year Plan, the Soviet state relied on the expert knowledge of groups of German and other foreign workers (architects, planners, skilled labourers) to design and build the standardized housing projects for industrial cities. This paper outlines the complicated transfer of Western planning ideas and designs into actual built spaces, focusing on the gap between initial plans and the makeshift and provisional types of housing that were constructed in the Soviet industrial city of the early 1930s, amidst escalating attacks on functionalist architecture and constantly fluctuating attitudes toward foreign specialists. 相似文献
10.
Natallia V. Dubashynskaya Anton N. Bokatyi Alexey S. Golovkin Igor V. Kudryavtsev Maria K. Serebryakova Andrey S. Trulioff Yaroslav A. Dubrovskii Yury A. Skorik 《International journal of molecular sciences》2021,22(20)
The development of intravitreal glucocorticoid delivery systems is a current global challenge for the treatment of inflammatory diseases of the posterior segment of the eye. The main advantages of these systems are that they can overcome anatomical and physiological ophthalmic barriers and increase local bioavailability while prolonging and controlling drug release over several months to improve the safety and effectiveness of glucocorticoid therapy. One approach to the development of optimal delivery systems for intravitreal injections is the conjugation of low-molecular-weight drugs with natural polymers to prevent their rapid elimination and provide targeted and controlled release. This study focuses on the development of a procedure for a two-step synthesis of dexamethasone (DEX) conjugates based on the natural polysaccharide chitosan (CS). We first used carbodiimide chemistry to conjugate DEX to CS via a succinyl linker, and we then modified the obtained systems with succinic anhydride to impart a negative ζ-potential to the polymer particle surface. The resulting polysaccharide carriers had a degree of substitution with DEX moieties of 2–4%, a DEX content of 50–85 μg/mg, and a degree of succinylation of 64–68%. The size of the obtained particles was 400–1100 nm, and the ζ-potential was −30 to −33 mV. In vitro release studies at pH 7.4 showed slow hydrolysis of the amide and ester bonds in the synthesized systems, with a total release of 8–10% for both DEX and succinyl dexamethasone (SucDEX) after 1 month. The developed conjugates showed a significant anti-inflammatory effect in TNFα-induced and LPS-induced inflammation models, suppressing CD54 expression in THP-1 cells by 2- and 4-fold, respectively. Thus, these novel succinyl chitosan-dexamethasone (SucCS-DEX) conjugates are promising ophthalmic carriers for intravitreal delivery. 相似文献