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1.
This study deals with the formulation of natural drugs into hydrogels. For the first time, compounds from the sage essential oil were formulated into chitosan hydrogels. A sample preparation procedure for hydrophobic volatile analytes present in a hydrophilic water matrix along with an analytical method based on the gas chromatography coupled with the mass spectrometry (GC-MS) was developed and applied for the evaluation of the identity and quantity of essential oil components in the hydrogels and saline samples. The experimental results revealed that the chitosan hydrogels are suitable for the formulation of sage essential oil. The monoterpene release can be effectively controlled by both chitosan and caffeine concentration in the hydrogels. Permeation experiment, based on a hydrogel with the optimized composition [3.5% (w/w) sage essential oil, 2.0% (w/w) caffeine, 2.5% (w/w) chitosan and 0.1% (w/w) Tween-80] in donor compartment, saline solution in acceptor compartment, and semi-permeable cellophane membrane, demonstrated the useful permeation selectivity. Here, (according to lipophilicity) an enhanced permeation of the bicyclic monoterpenes with antiflogistic and antiseptic properties (eucalyptol, camphor and borneol) and, at the same time, suppressed permeation of toxic thujone (not exceeding its permitted applicable concentration) was observed. These properties highlight the pharmaceutical importance of the developed chitosan hydrogel formulating sage essential oil in the dermal applications.  相似文献   
2.
The enzymatic conversion of lignins, possibly in combination with electrochemical oxidation, makes aromatics such as syringol, guaiacol, vanillin and catechol available in the qualities required by the fragrance industry. The lignins were obtained by soda digestion from wheat straw and Miscanthus, characterized and then converted with laccases. The overall yield amounted up to 9 wt % with a product spectrum confined to four substances. Catechol was the major product, with a fraction of ≈75 %. It can easily be isolated by extraction with acetone.  相似文献   
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4.
The need for electronics to operate at temperatures of 200°C and above continues to grow. These applications include avionics, aerospace, automotive, downhole drilling, mining, and many others. To satisfy this demand, a significant amount of research and development has been conducted. Despite the efforts, the number of new electronic components designed specifically for high-temperature operation is still relatively limited. In Low Temperature Co-fired Ceramic (LTCC) packages, LTCC materials are generally used as the host media for a number of pre-fabricated semiconductor components. As a result, reliability of the entire LTCC package largely depends on the performance of the least robust component. Ferro A6M-E and Ferro L8 are the two well-established and recognized LTCC dielectrics widely used for mid and high frequency LTCC applications, including several high reliability aerospace and defense applications that require demanding Mil-Spec qualifications. This study is our first attempt to characterize and understand basic high-temperature dielectric properties of these two commercial LTCC materials. The secondary objective is to initiate a dialogue in attempt to establish reliability requirements for LTCC packages dedicated for high-temperature operation.  相似文献   
5.
The ozonation of two differently substituted azo dyes (Schwarz GRS and Orange Acid 8) in water media is studied. The influence of pH on the effectiveness of the ozonation at various initial concentrations of each dye is explored. It was found out that the rates of decolorization for amino-group substituted dyes reflect the considerable influence by the widely varying initial pH from 4.5 to 10. Specifically, the highest effect of decolorization of this dye was obtained at the highest pH studied (pH 10) for all initial concentrations of the solutions. Considering the dye without an amino-group substitute, the rates of color disappearance in ozonation reflected to a lower degree the variations of the initial pH. Pseudo-first-order trends of decolorization were observed in all the experimental runs. Regarding the kinetic results obtained, an attempt to explain the different dyes reactivity was made based on the absolute electronegativity (Elumo + Ehomo) of both dyes. The COD/BOD analysis shows that the ozonation of both azo dyes can reduce the sample COD but it could not improve the biodegradability ratio (BOD5/COD). BOD decrease with ozonation time indicates that the intermediates of the ozonation are of lower biodegradability. Oxalic acid was found as the final product of ozonation of both dyes.  相似文献   
6.
Healthcare institutions typically post their privacy practices online as privacy policy documents. We conducted a longitudinal study that examines the effects of HIPAA's enactment on a collection of privacy policy documents for a fixed set of organizations over a four-year period. We present our analysis of 24 healthcare privacy policy documents from nine healthcare Web sites, analyzed using goal mining, a content-analysis method that supports extraction of useful information about institutions' privacy practices from documents. We compare our results to our pre-HIPAA study of these same institutions' online privacy practices and evaluate their evolution in the presence of privacy laws  相似文献   
7.
Aqueous molal solutions of xylose and lysine (initial pH 4–9) were refluxed either with control of the pH at 5–0 or without pH control (final pH 2–6). Analysis by gas chromatography (GC) and GC-mass spectrometry resulted in the identification of 58 and 28 compounds, respectively, from the two systems. Furans were the main reaction products in both systems and 2-furfural alone comprised 522 and 999 g kg?1 of the volatiles, respectively, from the systems with final pH values of 5–0 and 2–6. Maintaining the pH at 5–0 resulted in a higher yield and greater numbers of nitrogen-containing compounds, and monocyclic pyrroles, pyridines and 2,3-dihydro-l H-pyrrolizines were identified only in that system. Aliphatic compounds, alicyclic compounds, benzene derivatives. l-(2–furfuryl)pyrroles and pyrazines were also identified. This investigation is the first report of the formation of 2.3-dihydro-l H-pyrrolizines in a model system containing lysine as the amino compound; a possible mechanism is proposed.  相似文献   
8.
The adoption of unified fracture mechanics terminology (UFMT) will promote efficient communication between specialists in different fields of fracture research, harmonization of national and international standards relating to fracture mechanics, and last but not least improvement of the existing methodology for teaching and education in fatigue and fracture. In this paper the definitions of some basic and related terms included in different standards on fracture mechanics terminology are confronted with one another. Alternative definitions of the same terms are offered. By this strategy the author tries to show that the definitions of basic and related terms appropriate for the UFMT should emerge as a consequence of harmonizing a crack model with an actual crack and then both taken together with a fracture model, laboratory test methods, and failure assessment codes.Published in Problemy Prochonsti, No. 1, pp. 17–29, January, 1996.This paper is published as a matter of discussion.  相似文献   
9.
Introduction of the BER? KOMPAKS® automated system at the Vyksa Metallurgical Plant to safely and efficiently manage the operation of the plant’s equipment has allowed the facility to begin operating that equipment based on real-time evaluations of its actual physical condition. Introduction of the new system has also allowed better coordination of repair-scheduling with ongoing production operations, significantly improved the reliability and readiness of the equipment for operation at 100% capacity, completely eliminated the human factor from the process of monitoring the condition of equipment, and made it possible to check the quality and timeliness of equipment maintenance and repair work so as to ensure safe, efficient operation of the entire production complex.  相似文献   
10.
Optimal synthesis of tunable elastic wave-guides   总被引:1,自引:0,他引:1  
Topology optimization, or control in the coefficients of partial differential equations, has been successfully utilized for designing wave-guides with precisely tailored functionalities. For many applications it would be desirable to have the possibility of drastically altering the wave-guiding properties of a device “on the fly,” in a controllable manner as an influence of some external input. This would enable wave-guides with highly non-linear input-output mappings, such as for example controllable wave switches.In this paper, we propose using finite elastic pre-straining for the purpose of tuning a wave-guide. In order to systematically formulate and solve the wave-guide synthesis problems we utilize mathematical programming methods in conjunction with topology optimization for parametrizing the design space. The resulting extremal problem is, from a practical point, equivalent to finding an optimal subdivision of a given control volume into two disjoint subsets occupied by two different materials, normally resulting in a highly heterogeneous elastic body with desired wave-guiding functionalities in the original and finitely deformed configurations.The proposed methodology is illustrated with numerical examples.  相似文献   
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