真空断路器真空度与灭弧室屏蔽罩上感应电位联系机理研究

屏蔽罩电位是判断真空断路器灭弧室真空度水平优劣的一种技术手段,研究人员对屏蔽罩电位信号成分及其形成机理进行了大量的研究工作,并在理论上和试验方面取得了一定成果。但对于真空屏蔽罩上电位的成因并无公认的解释,且实际应用中难以将不同型号的断路器按同一标准对待。为寻求真空度与屏蔽罩电位的内在联系机理,本文基于前人研究成果,从电介质学及气体放电的相关理论出发,将真空度劣化过程分成三个阶段分别讨论,阐述了各个阶段依据理论基础。特别针对真空度高于0.1 Pa时较难判断的屏蔽罩电位值,利用有限元分析的方法进行了3D电场计算,分析了该真空度范围下屏蔽罩电位的变化规律,研究成果提供了一种真空度判断与评估的可行方法,具有较好的应用参考价值。     

Gemifloxacin mesylate (GFM): dissolution test based on in vivo data

Gemifloxacin mesylate (GFM) is a synthetic, broad-spectrum, fluoroquinolone antibacterial agent. It is different from other class members because it achieves adequate plasma concentrations to inhibit both topoisomerase IV and gyrase. The aim of this study was to develop and validate a dissolution test for GFM in coated tablets, using a simulated absorption profile based on in vivo data obtained from the literature. The fraction and percentage of the dose absorbed were calculated using model-dependent Loo-Riegelman approach for two compartments. The best in vitro dissolution profile was obtained using 900?mL of pH 6.0 phosphate buffer as a dissolution medium at 37?°C?±?0.5?°C and paddles at 50?rpm. The in vitro dissolution samples were analyzed using a liquid chromatography method, and the validation was performed according to USP 34 (2011). The method showed specificity, precision, accuracy, robustness and linearity. Under these conditions, a level-A in vitro–in vivo correlation was suggested (r?=?0.9926). The prediction errors were calculated to determine the validity and accuracy of the suggested correlation. The dissolution test can be used to evaluate the dissolution profile of GFM-coated tablets and minimize the number of bioavailability studies as part of new formulation development.     

Olefin incorporation on supported FeCo alloy Fischer-Tropsch catalysts

We have previously reported on the properties of silicasupported Fe, Co and FeCo alloy for the Fischer-Tropsch (FT) reaction, both at atmospheric pressure and up to 14 atm (14 × 1·0133 × 10⁵ Pa). The selectivity for C₂−C₃ olefins reported in the literature for these catalysts (particularly FeCo) was found to be somewhat suppressed at higher pressures, although methanol production was enhanced. The present study is concerned with the possible role of olefin insertion on hydrocarbon chain growth and oxygenate production. Results for both ethylene and 1-pentene indicate some incorporation into the next higher carbon number product at low CO conversions, but not a significant effect on overall chain growth. There is a diminution of oxygenate formation with olefin-containing feeds for all catalysts and reaction conditions investigated (250°C, 1 and 7·8 atm). Present results do not exclude a role of olefin insertion in the mechanism of chain growth, but it seems to be a minor one at most. This paper is dedicated to Dr L K Doraiswamy on his sixtieth birthday. This research was supported by the Department of Energy, Office of Basic Energy Sciences, Contract DE-AC02-78ER04993.     

On the determination of optimal transition profile of a stepped bar in tension or in torsion by BEM

The objective is to have uniformly distributed tangential stresses on the transition profile of a stepped bar subjected to tensile and torsional loading using an axisymmetric boundary element formulation. The transition curve is represented by the Langragian interpolation polynomial with progressive degrees to avoid shape distortion during the optimization procedure. The calculated result is compared with that obtained by fluid dynamics given in the literature. It is seen that the transition curve obtained in this paper is reasonable.     

炭/炭复合材料石墨化度的表征(Ⅰ)

叙述了用Ｘ－射线衍射（ＸＲＤ）表征炭－石墨化度的来源,以及炭－石墨材料与炭／炭复合材料的不同点。在一定的实验基础和理论分析上,提出目前ＸＲＤ测试的Ｇ参数表征Ｃ／Ｃ复合材料的石墨化度时不完善,它只反映了Ｃ／Ｃ组分中石墨化度高的组分的石墨化性能。同时提出了两种Ｃ／Ｃ复合材料石墨化度表征的新方法,一是考虑衍射强度的Ｇ参数的修正公式;另一是利用激光拉曼光谱来表征。     

Models,algorithms and performance analysis for adaptive operating room scheduling

The complex optimisation problems arising in the scheduling of operating rooms have received considerable attention in recent scientific literature because of their impact on costs, revenues and patient health. For an important part, the complexity stems from the stochastic nature of the problem. In practice, this stochastic nature often leads to schedule adaptations on the day of schedule execution. While operating room performance is thus importantly affected by such adaptations, decision-making on adaptations is hardly addressed in scientific literature. Building on previous literature on adaptive scheduling, we develop adaptive operating room scheduling models and problems, and analyse the performance of corresponding adaptive scheduling policies. As previously proposed (fully) adaptive scheduling models and policies are infeasible in operating room scheduling practice, we extend adaptive scheduling theory by introducing the novel concept of committing. Moreover, the core of the proposed adaptive policies with committing is formed by a new, exact, pseudo-polynomial algorithm to solve a general class of stochastic knapsack problems. Using these theoretical advances, we present performance analysis on practical problems, using data from existing literature as well as real-life data from the largest academic medical centre in The Netherlands. The analysis shows that the practically feasible, basic, 1-level policy already brings substantial and statistically significant improvement over static policies. Moreover, as a rule of thumb, scheduling surgeries with large mean duration or standard deviation early appears good practice.     

Equivalence of the different Cm- and Cs-term expressions used in liquid chromatography and a geometrical model uniting them

It is shown that all C m and C s expressions ever established in the literature are intrinsically fully identical and can be derived from a simple parallel plug flow model. Analytically solving this model yields C m- and C s-term expressions that exactly correspond to the expressions obtained via either the method of moments (general rate model) or via Giddings' nonequilibrium theory. This holds for open-tubular as well as packed and monolithic columns. From this equivalence, a set of convenient "translation" expressions could be established, enabling a swift transition between the different C m- and C s-term expressions that currently coexist in literature. The link with the parallel plug flow model provides a good physical insight into the assumptions underlying the general rate model (e.g., a plug flow in the flow-through pores) and in the physical meaning of the different parameters involved in it. The parallel plug flow model also allows us to illustrate the difference between the zone and the phase retention factor and between the intraparticle diffusion coefficient and the effective diffusion coefficient used in the general rate model. These differences are subtle, but as they can have a large impact, they constitute important potential sources of confusion currently obscuring the modeling of HPLC columns.     

A test of inventory models with permissible delay in payment

Contrary to the long-standing view in the finance literature that firms should maximise payment delays, research in operations management suggests that long payment delays can be suboptimal. In this study, we reconcile these two views by applying a secondary data approach to established operations management theory. Based on a sample of 3383 groups of public US firms from a novel database, we find that our data are consistent with the causal relations and theoretical predictions of the operations management literature. Firm profitability is positively associated with payment delay. Payment delay, in turn, is positively associated with the capital cost difference between buyer and supplier and negatively associated with the price elasticity of demand and the deterioration rate of inventory. However, we do not observe any significant interaction effects between these factors, which raise a number of questions for future research.     

In vitro models to estimate drug penetration through the compromised stratum corneum barrier

Objectives: The phospholipid vesicle-based permeation assay (PVPA) is a recently established in vitro stratum corneum model to estimate the permeability of intact and healthy skin. The aim here was to further evolve this model to mimic the stratum corneum in a compromised skin barrier by reducing the barrier functions in a controlled manner. Methods: To mimic compromised skin barriers, PVPA barriers were prepared with explicitly defined reduced barrier function and compared with literature data from both human and animal skin with compromised barrier properties. Caffeine, diclofenac sodium, chloramphenicol and the hydrophilic marker calcein were tested to compare the PVPA models with established models. Results and discussions: The established PVPA models mimicking the stratum corneum in healthy skin showed good correlation with biological barriers by ranking drugs similar to those ranked by the pig ear skin model and were comparable to literature data on permeation through healthy human skin. The PVPA models provided reproducible and consistent results with a distinction between the barriers mimicking compromised and healthy skin. The trends in increasing drug permeation with an increasing degree of compromised barriers for the model drugs were similar to the literature data from other in vivo and in vitro models. Conclusions: The PVPA models have the potential to provide permeation predictions when investigating drugs or cosmeceuticals intended for various compromised skin conditions and can thus possibly reduce the time and cost of testing as well as the use of animal testing in the early development of drug candidates, drugs and cosmeceuticals.     

质检专业文献翻译技巧分析——以日语翻译为例

本文以质检日语翻译实践为例,分析质检翻译文体特征和翻译技巧。对质检口语、标准、计量、科技文献的翻译技巧进行了分析。     

The coordinated production and transportation scheduling problem with a time-sensitive product: a branch-and-cut algorithm

In many supply chain scenarios in which short lifespan products are considered, production and transportation decisions must be made in a coordinated manner with no inventory stage. Hence, a solution to this problem conveys information about production starting times of each product lot at facility and delivery times of the lots to various customer-sites located in different geographic regions. In this paper, we study a variant of the problem that single product with limited shelf life is produced at single facility. Once produced, production lot is directly distributed to the customers with non-ignorable transportation time by single vehicle having limited capacity before the lifespan. Objective is to determine the minimum time required to produce and deliver all customer demands. To this end, we develop a branch-and-cut (B&C) algorithm using several valid inequalities adopted from the existing literature to improve lower bounds and applying a local search based on simulated annealing approach to improve upper bounds. On test problems available in the literature, we evaluate the performance of the B&C algorithm. Results show the promising performance of the B&C algorithm.     

细菌纤维素基磁性纳米复合材料的研究进展

细菌纤维素作为一种新型的生物纳米材料,不同于植物纤维素,其较高的比表面积、精细的三维纳米网状结构和表面大量的活性反应位点可以作为"模板"反应使用,通过原位复合的方法可有效地控制、合成具有预期特定形貌与尺寸且分布均匀的磁性纳米复合材料,从而获得良好的综合性能。从细菌纤维素作为"模板"制备功能化材料的机理出发,归纳总结了近年来细菌纤维素基磁性材料的研究进展,着重归纳了解决磁性膜材料的颗粒团聚问题的方法,并展望了细菌纤维素基磁性材料的发展趋势。     

Onychopharmacokinetics of terbinafine hydrochloride penetration from a novel topical formulation into the human nail in vitro

This study determined the onychopharmacokinetics, nail absorption, distribution, and penetration of [¹⁴C]-terbinafine HCl in a new topical formulation into/through the human finger nail using the in vitro finite dose model. This study determined the penetration rate of terbinafine HCl from multiple doses of topical formulation applied daily for 14 days. Results showed that the total dose recovery (mass balance) was almost 100%. The concentration of terbinafine HCl in the deeper nail plate (ventral/intermediate layers) and the cotton-pad nail bed samples after the 14-day treatment were 613?±?145 and (±S.D.) and 27?±?1.2 µg/cm³ (or 1.9?±?0.6 µg/cm³ daily) on average, respectively. In comparison with nail concentration data from the literature for other topical terbinatine formulations, our results show that higher amounts of terbinafine HCl reached the deep nail plate and/or the nail bed after a 14-day topical treatment with this topical formulation in vitro.     

形变铜基原位复合材料的研究进展

本文对形变铜基原位复合材料的基本原理、制备方法、组织和性能特点等进行了综述，并分析指出了需进一趟研究的几个问题。     

In vitro dissolution method fitted to in vivo absorption profile of rivaroxaban immediate-release tablets applying in silico data

Objective: This study aimed to develop and validate an in vitro dissolution method based on in silico–in vivo data to determine whether an in vitro–in vivo relationship could be established for rivaroxaban in immediate-release tablets.

Significance: Oral drugs with high permeability but poorly soluble in aqueous media, such as the anticoagulant rivaroxaban, have a major potential to reach a high level of in vitro–in vivo relationship. Currently, there is no study on scientific literature approaching the development of RIV dissolution profile based on its in vivo performance.

Methods and results: Drug plasma concentration values were modeled using computer simulation with adjustment of pharmacokinetic properties. Those values were converted into drug fractions absorbed by the Wagner–Nelson deconvolution approach. Gradual and continuous dissolution of RIV tablets was obtained with a 30?rpm basket on 50?mM sodium acetate +0.2% SDS, pH 6.5 medium. Dissolution was conducted for up to 180?min. The fraction absorbed was plotted against the drug fraction dissolved, and a linear point-to-point regression (R²?=?0.9961) obtained.

Conclusion: The in vitro dissolution method designed promoted a more convenient dissolution profile of RIV tablets, whereas it suggests a better relationship with in vivo performance.     

Differences in wood material responses for radial and tangential direction as measured by dynamic mechanical thermal analysis

Wood is a complex cellular structure with different properties in the radial and tangential direction. Many researchers have measured dynamic properties in the longitudinal direction and a few in the radial direction but very little data can be found in the literature on dynamic mechanical properties in the tangential direction. The purpose of the work presented in this paper was to investigate the dynamic mechanical behaviour in the radial and tangential directions of wood (Pinus sylvestris). Testing was done in tension at 1 Hz with a Dynamic Mechanical Thermal Analyser. Properties in radial and tangential direction were different. The radial direction showed a higher elastic modulus and lower loss factor levels at temperatures between –120°C and 80°C. The tangential direction had on average a higher peak temperature than the radial direction for a loss factor peak around –80°C. It is the opposite of synthetic composites where the stiffer direction has a higher peak temperature. A loss factor peak at around 0°C was seen, most significantly in the tangential direction. This peak has scarcely been reported in the literature before. The distance between annual rings did not significantly affect the dynamic behaviour in the tangential direction.     

Optical constants of in situ-deposited films of important extreme-ultraviolet multilayer mirror materials

We have performed angle-dependent reflectance measurements of in situ magnetron sputtered films of B(4)C, C, Mo, Si, and W. The Fresnel relations were used to determine the complex index of refraction from the reflectance data in the region of approximately 35-150 eV. In the cases of Si, C, and B(4)C we found excellent agreement with published data. However, for Mo and W we found that the optical properties from 35 to 60 eV differed significantly from those in the literature.     

Temperature Dependence of Resin Flow in a Resin Film Infusion (RFI) Process by Ultrasound Imaging

Ultrasonic imaging in the C-scan mode was used in conjunction with the amplitude of the reflected signal to measure the temperature dependence of resin flow rate in single layers of woven carbon fabric. The RFI samples were vacuum-bagged and scanned in a water tank at 50°C, 60°C, 70°C, and 80°C. The measured flow rates were plotted versus inverse viscosity to determine the permeability in the thin film, non-saturated system. The permeability values determined in this work were consistent with permeability values reported in the literature. Capillary flow was not observed at the temperatures and times required for pressurized flow to occur. The flow rate at 65°C was predicted from the measured flow rates, and then measured in a 10-layer laminate. The investigation demonstrates that ultrasonic imaging in the C-scan mode in conjunction with the amplitude of the reflected signal is an effective method for measuring resin flow through fabric.     

A deductive approach to select or rank journals in multifaceted subject, Oceanography

Whether singleton approach (citation analysis of identified source journals) used by Gross and Gross (Science 66(1713):385?C389, 1927) or differential approach (citation analysis of articles in specific subject field) applied by Bradford (Engineering 137:85?C86, 1934) suitable to select or rank journals in multifaceted subject????Oceanography?? is presented. This study discusses both the approaches analyzing citations of published literature in oceanography from 30 countries. The ranking correlation of journals showed better positive correlation (lowest ???=?0.662 for 2005?C2009 to highest ???=?0.817 for 1995?C1999) when top ranked journals from the list generated complying Gross and Gross approach (GA) were correlated with same journal titles of the list generated complying Bradford approach than the other way (lowest ???=?0.588 for 2005?C2009 to highest ???=?0.726 for 1990?C1994). Both the approaches matched similar number of journals to country-wise lists and give unbiased choice in preferring a ranking list. The journals distribution graphs showed typical Bradford?CLeimkuhler curves in both the approaches for all the datasets. But the groos droop appears comparatively early with shorter straight line in GA. The high clustering of literature to limited number of journals is a disadvantage in multifaceted subject. So the differential approach used by Bradford is being considered suitable for multifaceted subject like, ??Oceanography??.     

碳纤维增强聚乳酸复合材料体外降解特性

制备了碳纤维增强聚乳酸(C/ PLA) 骨折内固定复合材料, 研究了体外降解过程中其力学性能的变化。结果表明: 在体外降解过程中, C/ PLA 复合材料的各项力学性能均有不同程度的下降, 但经过硝酸处理后的C/PLA 复合材料降解速度缓慢, 表明界面结合强度的提高对降解过程起抑制作用。