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排序方式: 共有4126条查询结果,搜索用时 15 毫秒
1.
In 1937, Sir H. A Krebs first published the Citric Acid Cycle, a unidirectional cycle with carboxylic acids. The original concept of the Citric Acid Cycle from Krebs’ 1953 Nobel Prize lecture illustrates the unidirectional degradation of lactic acid to water, carbon dioxide and hydrogen. Here, we add the heart lactate dehydrogenase•proton-linked monocarboxylate transporter 1 complex, connecting the original Citric Acid Cycle to the flow of energy and material. The heart lactate dehydrogenase•proton-linked monocarboxylate transporter 1 complex catalyses the first reaction of the Citric Acid Cycle, the oxidation of lactate to pyruvate, and thus secures the provision of pyruvic acid. In addition, we modify Krebs’ original concept by feeding the cycle with oxaloacetic acid. Our concept enables the integration of anabolic processes and allows adaption of the organism to recover ATP faster. 相似文献
2.
Mohammed M. Mehanna Mohamad Ibrahim Shabarek Hoda A. Elmartadny 《Drug development and industrial pharmacy》2019,45(3):485-497
Pravastatin is a promising drug utilized in the treatment of hyperlipidemia, yet, its main clinical limitation is due to gastric liability which fractions its oral bioavailability to less than 18%. The purpose of the current study is to encapsulate pravastatin into Eudragit®-based spray-dried microparticles aspiring to overcome its acid liability. With the aim to optimize the microparticles, formulation and process parameters were studied through acid resistance challenging test. Physicochemical characterization of the optimized spray-dried pH-sensitive microparticles namely; in-vitro dissolution, surface morphology, compatibility, and solid-state studies were performed. Moreover, in-vivo evaluation of the microparticles and accelerated stability studies were carried out. The results outlined that polymer to drug ratio at 5:1 and pravastatin concentration at 1%w/w in spray-drying feed solution showed 38.55% and 53.97% encapsulation efficiency, respectively. The significance of process parameters specifically; the flow rate and the inlet temperature on microparticles surface integrity were observed, and optimized until encapsulating efficiency reached 72.37%. The scanning electron microscopical examination of the optimized microparticles illustrate uniform smooth surface spheres entrapping the drug in an amorphous state as proved through Differential Scanning Calorimetry (DSC) and Fourier Transfer Infrared (FTIR) studies. The in-vivo evaluation demonstrated a 5-fold enhancement in pravastatin bioavailability compared to the marketed product. The results provided evidence for the significance of spray-dried pH-sensitive microparticles as a promising carrier for pravastatin, decreasing its acid liability, and improving its bioavailability. 相似文献
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4.
Jagoda O. Szafrańska Bartosz G. Sołowiej 《International Journal of Food Science & Technology》2020,55(5):1971-1979
The objective of this study was the evaluation of different fibres (bamboo, acacia, potato or citrus) addition on texture, rheological and sensory properties of acid casein processed cheese sauces. Fibres used in production of sauces had an impact on the texture, viscosity, viscoelastic and sensory properties. The largest increase in viscosity was observed in products with addition of potato fibre, which have good water holding and adsorption capacity. Processed cheese sauce with the addition of citrus fibre was characterised by the highest values in general, and the increase of this feature in the tested samples was regular. Adhesiveness was the highest in products with 1% addition of every fibre. The lowest values of viscosity single shear, G′ and G″ moduli, among all tested, had sauces with acacia fibre. Moreover, they had the most thin liquid consistency, which was different from preferred one. 相似文献
5.
《Journal of the European Ceramic Society》2020,40(4):1111-1118
Highly textured TiB2 ceramics were prepared by slip casting an aqueous suspension in a magnetic field of 9 T, followed by sintering using Field Assisted Sintering Technology (FAST). Particle size refinement by ball milling improved both the degree of texturing and densification of the material (RD > 98 %). The sintered material exhibited a Lotgering orientation factor of 0.90, with the c-axis of TiB2 oriented parallel to the magnetic field and FAST pressing direction. The texturing effect induced by the uniaxial pressing was negligible. The textured TiB2 material exhibited a significant anisotropy in mechanical properties; the values of hardness and indentation elastic modulus measured along directions transverse to the c-axis of TiB2 were 37 % and 13 % higher than the ones measured along the c-axis direction. Moreover, the specific wear rate of a surface of textured TiB2 parallel to the field was one order of magnitude lower than a surface perpendicular to the field. 相似文献
6.
以连续芳纶纤维(Kevlar)为增强体,热塑性聚乳酸(PLA)为基体,采用熔融沉积成型(FDM)工艺,设计并制备了一体成型的Kevlar/PLA波纹夹层结构复合材料。研究了Kevlar/PLA波纹夹层结构复合材料在压缩载荷下的断裂模式,分析了结构参数、工艺参数对试样的压缩性能和结构密度的影响。结果表明,随着芯层波纹数量的增加,试样的压缩性能与结构密度均呈增大趋势;随着芯层波纹高度的增大,试样的压缩强度先增大后减小,结构密度不断减小;随着打印层高的增大,试样中的纤维体积含量不断减少,试样的压缩强度略有下降。 相似文献
7.
《International Journal of Hydrogen Energy》2020,45(43):23056-23068
A series of monometallic and bimetallic palladium gold catalyst were prepared and studied for the formic acid dehydrogenation reaction. Different Pd/Au compositions were employed (PdxAu100-x, where x = 25; 50 and 75) and their impact on alloy structure, particle size and dispersion was evaluated. Active phase composition and reaction parameters such as temperature, formic acid concentration or formate/formic acid ratio were adjusted to obtain active and selective catalyst for hydrogen production. An important particle size effect was observed and related to Pd/Au composition for all bimetallic catalysts. 相似文献
8.
Jianfeng Wu Cheng Hu Chen Ping Xiaohong Xu Weiheng Xiang 《Ceramics International》2018,44(16):19590-19596
To prolong the service life of cordierite–spodumene composite ceramics applied to the solar heat transmission pipeline, the zircon modifier was introduced to improve the corrosion resistance of the ceramics. The effects of zircon on the density, bending strength, crystalline phase, microstructure and chemical stability were studied. The results showed that the sintering temperature range of the composite ceramics was broadened to 40–60?°C with the introduction of 5–15?wt% zircon. Moreover, the mechanical strength and corrosion resistance of the ceramic materials were improved with the zircon introduction. In particular, sample C3 containing 15?wt% of zircon and sintered at 1360?°C exhibited the best performance, which had the 0.03% Wa, 0.07% Pa, 2.34?g?cm?3 Db and 100.17?MPa bending strength. After acid and alkali corrosion, the water absorption was still less than 0.5% and the strength loss rate decreased to less than 5.3%. The XRD and SEM analyses demonstrated that the ZrSiO4 grains dispersed at the grain boundaries could enhance the mechanical properties. Furthermore, the existence of the Zr4+ ions not only reduced the cationic solubility of the glassy phases but also led to a reaction with OH? to form Zr(OH)4 on the surfaces. This improved the corrosion resistance of the composite ceramics and endowed it with a high residual strength after the acid and alkali corrosion. 相似文献
9.
Karolina M. Wójciak Dariusz M. Stasiak Joanna Stadnik Karolina Ferysiuk Anna Kononiuk 《International Journal of Food Science & Technology》2019,54(1):75-83
In this study, the influence of sonication time on the biogenic amines formation as a critical point in uncured dry-fermented beef manufacturing was studied. Samples of musculus semimembranosus were sonicated at different times (5 and 10 min) using ultrasound cold bath (4 °C) in acid whey (US 40 kHz and acoustic power 480 W). The effect of sonication on biogenic amine (BA) formation was investigated during 93 days of ripening period. Other parameters (pH value, water activity, microbial counts) that might provide further information on the product under study were also determined. The use of ultrasound during beef marinating in acid whey has a positive effect on retarding histamine (HIS), cadaverine (CAD), tyramine (TYR) and putrescine (PUT) formation. Moreover, the sonication treatment did not inhibit the growth of lactic acid bacteria (LAB) in dry-fermented beef during the whole ripening period. The pathogen bacteria (Staphylococcus aureus, Clostridium sp., Listeria monocytogenes) were not detected in all samples neither after 31 nor after 93 days of ripening period. 相似文献
10.
《International Journal of Hydrogen Energy》2020,45(17):10334-10341
Synergistic effect of sodium borohydride (NaBH4) mixed with waste aluminum in hydrolytic system were investigated to improve the hydrogen generation (HG) efficiency. The alkaline aqueous originated from NaBH4 hydrolysis impels the passive aluminum hydroxide film of Al surface to be dissolved, thus, mutual effect of HG amount increasing by 88% and 50% for Al powder and waste Al can, respectively. To add acid catalyst in the mutual mixture system prompts to significantly accelerate HG rate from 100 ml/min˙g to 400 ml/min˙g but raising temperature is not obviously found. It is speculated that exothermic effect dominates the NaBH4 hydrolytic reaction and eliminates the temperature effect. In this study, the mutual hydrolyzed reaction of NaBH4 and waste Al provides ecofriendly environment, low cost and enables to achieve higher HG rate and further uses for portable/mobile fields. 相似文献