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排序方式: 共有53条查询结果,搜索用时 46 毫秒
1.
Alexandra Kodadová Zuzana Vitková Petra Herdová Anton Ťažký Jarmila Oremusová Daniel Grančai 《Drug development and industrial pharmacy》2015,41(7):1080-1088
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.
Glassey C.R. Shanthikumar J.G. Seshadri S. 《Semiconductor Manufacturing, IEEE Transactions on》1996,9(4):536-549
We consider the problem of reducing the cycle time required for producing wafers at a given rate in high-volume single-product semiconductor fabs. Based on theoretical results, we propose a new method of input control that uses intersecting hyperplanes to decide when to release a new lot into the wafer fab. The release control rules constructed thus are said to belong to the class of linear control rules. We provide numerical examples to demonstrate that our method gives nearly optimal results for flowline and probabilistic reentrant flowline models. We then propose the linear control rule called descending control (DEC) and give a hybrid simulation-optimization procedure for determining DEC rules in real-life settings. We provide numerical results for the HP development fab model of Wein 相似文献
3.
Jn Cvengro Jarmila Paligov Zuzana Cvengroov 《European Journal of Lipid Science and Technology》2006,108(8):629-635
Castor oil is a non‐traditional raw material for the preparation of methyl and ethyl esters of higher fatty acids as alternative fuels for diesel engines. Castor oil contains ricinoleic acid (12‐hydroxy octadecene acid) with a major share of about 90%. The article presents the parameters of castor oil‐based methyl esters (COME) and ethyl esters (COEE) defined by the standard EN 14 214. The densities of COME and COEE are higher than the limit defined by the standard EN 14 214. The viscosities are more than twice as high as the limit value. The cetane numbers are lower than defined by the standard EN 14 214. For the remaining parameters, COME and COEE meet, in principle, the standard EN 14 214. The presence of the free hydroxyl group has virtually no effect on the values of such parameters as carbon residue, filterability at low temperatures and oxidation stability, for which some influence was expected. The physicochemical parameters of the castor oil esters are discussed in comparison to the analogous esters of high‐oleic sunflower oil, which contain about 80% of oleic acid. Both the methyl and ethyl esters of high‐oleic sunflower oil meet the standard EN 14 214 in all prescribed parameters. 相似文献
4.
Alvaro J. Romera Gil Levy Pierre C. Beukes Dave A. Clark Chris B. Glassey 《Nutrient Cycling in Agroecosystems》2012,92(3):329-346
On New Zealand dairy farms, it is the nitrogen excreted directly onto pasture, particularly urine, that drives nitrogen (N)
leaching from the farm. A new framework (UPF: Urine Patch Framework) is presented that post-processes the results of a whole
farm model and runs a mechanistic soil model to simulate the urine patches. Two alternative methods to simulate the spatial
distribution of urine patches were implemented and compared (Grid: spatially explicit, and Probabilistic: based on the probability of different temporal urination patterns). This paper describes the implementation of these two
methods in connection with a Whole Farm Model; and compares the N leaching predictions with observed data. Two examples are
provided, one analyzing the impact of urine patch overlap and another, the relative risk of N leaching at different times
of urinary N deposition. The model showed good correlation and predictive ability between simulated annual N leaching results
and observed data [R2 = 94 %, mean relative prediction error (MRPE) = 10 % for Grid and R2 = 72 %, MRPE = 20 % for Probabilistic]. The two methods produced similar results across an 8-year period for monthly and annual N leaching (R2 = 96 %, MRPE = 10 % and R2 = 86 %, MRPE = 8 %; respectively). Only 8 % of the paddock area was covered with multiple urinations during 1 year, but as
much as 39 % of the total urine volume was deposited on overlapped patches. Systematically removing all urinary N for 1 month
in either May or June reduced N leaching by approximately 20 %. Avoiding urinary N deposition during autumn or early winter
could be highly effective in mitigating N leached during the following winter. 相似文献
5.
6.
Patrik Palacka Anna Gvozdjkov Zuzana Rausov Jarmila Kucharsk Jn Slopovský Jana Obertov Daniel Furka Samuel Furka Keshav K. Singh Zuzana Sumbalov 《International journal of molecular sciences》2022,23(1)
Mitochondrial bioenergetics reprogramming is an essential response of cells to stress. Platelets, an accessible source of mitochondria, have a crucial role in cancer development; however, the platelet mitochondrial function has not been studied in urothelial carcinoma (UC) patients. A total of 15 patients with UC and 15 healthy controls were included in the study. Parameters of platelet mitochondrial respiration were evaluated using the high-resolution respirometry method, and the selected antioxidant levels were determined by HPLC. In addition, oxidative stress was evaluated by the thiobarbituric acid reactive substances (TBARS) concentration in plasma. We demonstrated deficient platelet mitochondrial respiratory chain functions, oxidative phosphorylation (OXPHOS), and electron transfer (ET) capacity with complex I (CI)-linked substrates, and reduced the endogenous platelet coenzyme Q10 (CoQ10) concentration in UC patients. The activity of citrate synthase was decreased in UC patients vs. controls (p = 0.0191). γ-tocopherol, α-tocopherol in platelets, and β-carotene in plasma were significantly lower in UC patients (p = 0.0019; p = 0.02; p = 0.0387, respectively), whereas the plasma concentration of TBARS was increased (p = 0.0022) vs. controls. The changes in platelet mitochondrial bioenergetics are consistent with cell metabolism reprogramming in UC patients. We suppose that increased oxidative stress, decreased OXPHOS, and a reduced platelet endogenous CoQ10 level can contribute to the reprogramming of platelet mitochondrial OXPHOS toward the activation of glycolysis. The impaired mitochondrial function can contribute to increased oxidative stress by triggering the reverse electron transport from the CoQ10 cycle (Q-junction) to CI. 相似文献
7.
Enhancement of magnetic losses in hybrid polymer composites with MnZn-ferrite and conductive fillers
Robert Moučka Alexander V. Lopatin Natalia E. Kazantseva Jarmila Vilčáková Petr Sáha 《Journal of Materials Science》2007,42(22):9480-9490
Polymer composites (PCs) with a polyurethane (PU) matrix filled with magnetic filler (MnZn ferrite) and hybrid polymer composites
(HPCs) consisting of this magnetic filler and various types of conductive fillers (carbon black, carbon fibers, aluminum powder,
polypyrrole) are prepared. The matrix structure of a HPC is formed (i) by a polymer filled with conductive filler, which forms
the skeleton of an infinite cluster, and (ii) by ferrite particles that are larger than conductive particles. Thus, an HPC
represents an ensemble of ferrite particles each of which is surrounded by a conductive medium and can be considered as a
“core–shell” structure. The development of a core–shell structure is evidenced by the lower electric percolation threshold
in an HPC compared with that in PU filled with conductive filler. Magnetic and dielectric spectra of PCs and HPCs are studied
in the frequency range from 1 MHz to 10 GHz. Hybrid systems exhibit a considerable enhancement of magnetic losses compared
with PCs. The enhancement of magnetic losses in HPCs is due to the conduction currents that are induced in the conductive
shell by a microwave magnetic field. 相似文献
8.
Marek Vochozka Anna Maroušková Jan Váchal Jarmila Straková 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(22):3332-3337
Steam-explosion pretreatment allows lowering of the natural resistance of plant material to subsequent biodegrading processes, such as anaerobic fermentation. This is achieved by a complex of cavitation forces that disintegrate rigid lignocellulose structures and liberate labile organic matter during a quick release of phytomass from a steam-pressurized reactor back to the atmospheric pressure. Hydrolyzing reactants or catalysts may increase the effect; however, the management of chemicals raises financial and environmental concerns. The current state of knowledge was reviewed to identify promising designs and reengineering that would enable subsequent transfer into the commercial scale in order to reverse the current trend of phytomass waste management – landfilling. In an effort to achieve profitability, it has been concluded that further development should focus on a deeper interconnection of the apparatus with associated technology units, reuse of waste heat from the subsequent biogas combustion, widening the range of processing parameters, reuse of nutrients, and utilization of the ballast organic matter. 相似文献
9.
Closed-loop job release control for VLSI circuit manufacturing 总被引:10,自引:0,他引:10
A closed-loop job release mechanism for job shops where the main source of randomness is due to machine failure and repair is introduced. The release policy adapts concepts of the reorder-point method of inventory control to the context of job-shop scheduling. The control mechanism, called starvation avoidance, is compared empirically with other input control mechanisms on several semiconductor wafer manufacturing job shops with favorable results 相似文献
10.
A graphical tool for inventory and production control, currently in use at a major US semiconductor manufacturer, is presented. The tool supports a bottleneck starvation avoidance policy. Equations for calculating the bottleneck in a clean room manufacturing environment are presented. A new constraint which must be satisfied to ensure starvation avoidance is introduced. A technique for helping a manual decision process conform to this constraint is presented. Many graphs are given to illustrate the concepts 相似文献