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991.
An operating system contains a replaceable unit whose wear (i.e. accumulated amount of damage) can be observed over time. When the wear reaches a certain level the unit is no longer able to function satisfactorily and needs to be replaced. Although units are produced to the same nominal specification there is still some random variation among them in their wear rates. This will be expressed by incorporating a random effect, or frailty term, in the model for individual degradation. There are costs for observing the wear on a unit, for replacing a unit, and for allowing a unit to fail before being replaced. When the last cost is comparatively large replacement before failure is preferable. For some standard examples of wear processes the lifetime distributions are obtained and the cost consequences of particular maintenance schemes are investigated. 相似文献
992.
对比研究了可压缩与不可压缩流体的Rayleigh Taylor不稳定性小扰动阶段的增长速率,其中,压力是密度的任意单值函数,这个函数也即是可压缩流体的状态方程。研究表明:在相同密度分布条件下,可压缩流体的界面扰动增长速率总是比相应的不可压缩流体的界面增长率大,其相对增长率随扰动波长的增加而增大,随两种介质的声速减小而增大,在长波和易压缩流体中,相对增长率可达0.8以上。因此,在某些条件下,流体可压缩性对Rayleigh Taylor不稳定性的影响是不能忽略的。 相似文献
993.
Taishun Liu 《Journal of Mathematical Analysis and Applications》2004,295(2):404-417
In this paper, we consider a normalized biholomorphic mapping f(x) defined on the unit ball in a complex Banach space, where the origin 0 is a zero of order k+1 of f(x)−x. The precise growth and covering theorem for f(x) is obtained when f(x) is a starlike mapping or a starlike mapping of order α. Especially, the precise growth and covering theorem for f(x) is also established when f(x) is a quasi-convex mapping. Moreover, the precise distortion theorem for f(x) is given when f(x) is a convex mapping. Our result includes many known results. 相似文献
994.
Rayees Ahmad Sheikh Sheikh Shreaz Guruaribam Shashikumar Sharma Luqman Ahmad Khan Athar Adil Hashmi 《Journal of Saudi Chemical Society》2012,16(4):353-361
A new organylborate ligand, potassium hydro (phthalyl) (salicylyl) borate and its Co(II), Ni(II), and Cu(II) complexes were synthesized. The compounds were characterized by elemental analysis, FTIR, 1H NMR, ESI MS, UV–Vis techniques, molar conductivity and magnetic data measurements. The spectroscopic data support a distorted square planar geometry around the Cu(II) ion, while the Co(II) and Ni(II) ions acquire a distorted octahedral geometry. These synthesised compounds were also tested for their in vitro antimicrobial activities against some bacterial and fungal strains to assess their inhibiting potential and the activities shown by these complexes were compared with standard drugs. Results showed that there is a marked increase in the antibacterial and antifungal activities of the cobalt(II) complex than the free ligand and other complexes when treated against the same microorganism at the same concentration. 相似文献
995.
996.
Naoya Kawakami Dr. Hiroki Sato Dr. Naohiro Terasaka Prof. Kunio Matsumoto Prof. Hiroaki Suga 《Angewandte Chemie (International ed. in English)》2023,62(36):e202307157
Receptor tyrosine kinases (RTKs) are generally activated through their dimerization and/or oligomerization induced by their cognate ligands, and one such RTK hepatocyte growth factor (HGF) receptor, known as MET, plays an important role in tissue regeneration. Here we show the development of ubiquitin (Ub)-based protein ligand multimers, referred to as U-bodies, which act as surrogate agonists for MET and are derived from MET-binding macrocyclic peptides. Monomeric Ub constructs (U-body) were first generated by genetic implantation of a macrocyclic peptide pharmacophore into a structural loop of Ub (lasso-grafting) and subsequent optimization of its flanking spacer sequences via mRNA display. Such U-body constructs exhibit potent binding affinity to MET, thermal stability, and proteolytic stability. The U-body constructs also partially/fully inhibited or enhanced HGF-induced MET-phosphorylation. Their multimerization to dimeric, tetrameric, and octameric U-bodies linked by an appropriate peptide linker yielded potent MET activation activity and downstream cell proliferation-promoting activity. This work suggests that lasso-grafting of macrocycles to Ub is an effective approach to devising protein-based artificial RTK agonists and it can be useful in the development of a new class of biologics for various therapeutic applications. 相似文献
997.
Jaleel CA Manivannan P Lakshmanan GM Gomathinayagam M Panneerselvam R 《Colloids and surfaces. B, Biointerfaces》2008,61(2):298-303
An experiment was conducted in two varieties, rosea and alba, of Catharanthus roseus plants with two watering treatments viz., 100 and 60% of field capacity, to understand the effects of water deficit on early growth, biomass allocation and photosynthetic pigment responses. We found that there were significant differences in early growth, dry matter accumulation and pigment variations between the two varieties. The root length, shoot length, total leaf area, fresh and dry weights were significantly reduced under water stress treatments. There was a significant reduction in the photosynthetic pigment contents in both the varieties. The rosea variety was more affected due to water deficit when compared to alba variety. 相似文献
998.
多羟基化合物法制备五次孪晶银纳米线的生长机理 总被引:2,自引:0,他引:2
运用多羟基化合物方法, 在添加表面活性剂聚乙烯吡咯烷酮(PVP) K30的溶液中合成了多次孪晶银纳米颗粒和纳米线. 运用透射电子显微术(TEM)和光吸收谱, 对不同的摩尔比n(PVP):n(AgNO3)和不同的搅拌条件下制备的纳米线进行了对比研究. 结果表明, 这种方法的制备过程中不仅存在由五个{111}面包裹成的锥形生长, 而且还同时存在垂直于生长方向的{110}层状生长, 并且两者之间还存在着竞争; 另外对纳米线的弯折处进行的高分辨电子显微学研究表明, 纳米线制备过程中遭受的塑性变形在纳米线中产生了大量的层错和位错; 纳米线折断产生的新鲜断口容易成为新的晶粒形核位置. 相似文献
999.
Muñiz-Valencia R Ceballos-Magaña SG Gonzalo-Lumbreras R Santos-Montes A Izquierdo-Hornillos RC 《Journal of separation science》2008,31(12):2303-2309
An improved sample preparation procedure for the determination of 17 steroids (corticoids (CC) and androgenic anabolic steroids (AAS)), used potentially as growth promoters, in feed samples has been developed. This procedure is based on two reported LC-UV methods. The improved procedure includes a leaching process using ACN, saponification, and SPE using polymeric cartridges. The proposed method was validated according to the EU criteria established for quantitative screening methods in PFS. The extraction efficiencies, decision limits (CCalpha) and detection capabilities (CCbeta), for these compounds were in the ranges of 82-100%, 19-40, and 24-53 microg/kg, respectively. The repeatability and the within-laboratory reproducibility at 1.0, 1.5, and 2.0 CCbeta levels were smaller than 10%. Accuracy was in the 97-101% range. The robustness was evaluated using the Youden robustness test. This method was applied to the analysis of steroids in different kinds of FS with satisfactory results. 相似文献
1000.
R. SanthakumariK. Ramamurthi Helen Stoeckli-EvansR. Hema W. Nirmala 《Physica B: Condensed Matter》2011,406(10):1872-1876
Synthesis of semiorganic material, triphenylphosphine oxide cadmium iodide (TPPOCdI), is reported for the first time. Employing the temperature reduction method, a crystal of size 16×7×6 mm3 was grown from dimethyl sulfoxide (DMSO) solution. Three dimensional crystal structure of the grown crystal was determined by single crystal X-ray diffraction study. The complex crystallizes in the chiral orthorhombic space group P212121. FTIR study was carried out in order to confirm the presence of the functional groups. UV-vis-NIR spectral studies show that the crystal is transparent in the wavelength range of 290-1100 nm. The microhardness test was carried out, and the load hardness was measured. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. Second harmonic generation efficiency of the powdered TPPOCdI, tested using Nd: YAG laser, is ∼0.65 times that of potassium dihydrogen orthophosphate. 相似文献