Model for practical prediction of natural carbonation in reinforced concrete: Part 1-formulation

A model is proposed for prediction of natural carbonation in reinforced concrete (RC) structures, and is potentially applicable to existing and new RC structures. The major components of the model comprise mathematical functions applied to predict the influence of concrete composition, and environmental factors on natural carbonation.This paper introduces the model concept and explains its structure including derivation, optimization and calibration. Over 163 data sets taken from a 10-year carbonation study were used in the model development and calibration. Only the experimental data that were based on outdoor natural exposure environment were employed in this research. Also in this study, the proposed model is compared with fib-Model Code 2010 using carbonation predictions generated from 346 data sets involving real world, highway structures. It is shown that the proposed model is comparably accurate and involves mainly basic tests with no major anticipated costs.     

Effects of N/C,P/C and Fe/C ratios on dark fermentative hydrogen gas production from waste paper towel hydrolysate

The effects of N/C, P/C and Fe/C ratios on dark fermentative hydrogen gas production from activated carbon treated WPT hydrolysate were investigated using Box–Behnken statistical experiment design. N/C, P/C and Fe/C ratios were chosen as independent variables while the H₂ yield and SHPR were set as the objective functions. H₂ yield and SHPR functions were described by two quadratic model functions. The addition of a proper amount of N, P and Fe to the fermentation media was found to be essential to enhance the H₂ production performance. Linear and interaction terms of N/C and Fe/C did have a significant effect on the H₂ yield in the model function. However, the SHPR was significantly affected by the linear and interaction terms of N/C and P/C. The most convenient N/C, P/C and Fe/C ratios resulting maximum H₂ yield (0.656 mol H₂/mol glucose) and SHPR (241.64 mL H₂/g biomass.h) were determined as 0.05, 0.09 and 0.003 (w/w), respectively.     

Time‐domain hybrid formulations for wave simulations in three‐dimensional PML‐truncated heterogeneous media

We are concerned with the numerical simulation of wave motion in arbitrarily heterogeneous, elastic, perfectly‐matched‐layer‐(PML)‐truncated media. We extend in three dimensions a recently developed two‐dimensional formulation, by treating the PML via an unsplit‐field, but mixed‐field, displacement‐stress formulation, which is then coupled to a standard displacement‐only formulation for the interior domain, thus leading to a computationally cost‐efficient hybrid scheme. The hybrid treatment leads to, at most, third‐order in time semi‐discrete forms. The formulation is flexible enough to accommodate the standard PML, as well as the multi‐axial PML. We discuss several time‐marching schemes, which can be used à la carte, depending on the application: (a) an extended Newmark scheme for third‐order in time, either unsymmetric or fully symmetric semi‐discrete forms; (b) a standard implicit Newmark for the second‐order, unsymmetric semi‐discrete forms; and (c) an explicit Runge–Kutta scheme for a first‐order in time unsymmetric system. The latter is well‐suited for large‐scale problems on parallel architectures, while the second‐order treatment is particularly attractive for ready incorporation in existing codes written originally for finite domains. We compare the schemes and report numerical results demonstrating stability and efficacy of the proposed formulations. Copyright © 2014 John Wiley & Sons, Ltd.     

Solubility and dissolution enhancement strategies: current understanding and recent trends

Identification of lead compounds with higher molecular weight and lower aqueous solubility has become increasingly prevalent with the advent of high throughput screening. Poor aqueous solubility of these lipophilic compounds can drastically affect the dissolution rate and subsequently the drug absorbed in the systemic circulation, imposing a significant burden of time and money during drug development process. Various pre-formulation and formulation strategies have been applied in the past that can improve the aqueous solubility of lipophilic compounds by manipulating either the crystal lattice properties or the activity coefficient of a solute in solution or both, if possible. However, despite various strategies available in the armor of formulation scientist, solubility issue still remains an overriding problem in the drug development process. It is perhaps due to the insufficient conceptual understanding of solubility and dissolution phenomenon that hinders the judgment in selecting suitable strategy for improving aqueous solubility and/or dissolution rate. This article, therefore, focuses on (i) revisiting the theoretical and mathematical concepts associated with solubility and dissolution, (ii) their application in making rationale decision for selecting suitable pre-formulation and formulation strategies and (iii) the relevant research performed in this field in past decade.     

MOA放电计数器用高通流ZnO电阻片的配方试验

在传统Bi2O3-ZnO系配方基础上,通过调整TiO2、SiO2、NiO等金属氧化物的配合量,改进添加剂制作工艺,JS-2#配方D90 mm×7mm电阻片,U5.5 kA小于1.5 kV、2 ms/2 200 A方波通过20次、性能稳定,可以满足特高压等级MOA放电计数器的性能要求。     

Improving dissolution kinetics of pharmaceuticals by fluidized bed impregnation of active pharmaceutical ingredients

Investigational drugs are increasingly becoming less soluble in aqueous media, thus, presenting real challenges during development. Previous work has successfully demonstrated the manufacturing of pharmaceuticals using fluidized bed (FB) impregnation of APIs onto porous carriers. This study demonstrates the usefulness of FB impregnation in formulating poorly soluble drugs. We show that dissolution of Fenofibrate is greatly improved by FB impregnation onto Neusilin^® (Fuji Health Science Inc, Burlington, NJ USA), a synthetic amorphous form of magnesium alumino‐metasilicate. We impregnate Neusilin^® for range of loadings and examine Fenofibrate's physical state. Dissolution of impregnated formulations is drug loading dependent and loadings below 40% show great improvement (decrease) in release time compared to physical blend. Release times are further improved by milling. We also examine feasibility of coimpregnating Fenofibrate with additives and observe stability (1.5 years) of the amorphous form of Fenofibrate inside Neusilin^®. This stabilization significantly improves Fenofibrate's dissolution kinetics, making our formulation comparable to one of the current market formulations, TriCor^® tablets (AbbVie Inc, North Chicago, IL USA). © 2016 American Institute of Chemical Engineers AIChE J, 62: 4201–4214, 2016     

25%吡唑·毒氟磷悬浮剂的研制

采用流点法、黏度曲线法确定润湿分散剂种类及用量,并通过筛选增稠剂、防冻剂等,确定25%吡唑·毒氟磷悬浮剂的最佳配方。其最佳配方组成为:5%吡唑醚菌酯、20%毒氟磷、3%7286、1.5%J601、1%1 1 06、0.2%黄原胶、1%硅酸镁铝、4%乙二醇、0.3%卡松、0.2%消泡剂1 860,水补足至1 00%。该制剂对黄瓜炭疽病防治效果良好,各项性能指标符合悬浮剂的相关标准,具有广阔的开发前景。     

Dynamic analysis of Coriolis flow meter using Timoshenko beam element

Coriolis mass flow meter (CFM) is used to measure the rate of mass flow through a pipe conveying fluid. In the present work, the Coriolis effect produced in the pipe due to a lateral excitation is modeled using the finite element (FE) method in MATLAB©. The coupled equation of motion for the fluid and pipe is converted to FE equations by applying Galerkin technique. The pipe conveying fluid is excited at its fundamental natural frequency. The time lag observed between symmetrically located measurement points which are equidistant from the point of excitation, is utilized to predict the mass flow rate. The results predicted by the present code is validated using the experimental, and numerical results published in the literature. The main contribution is the development of a FE model, using three node Timoshenko beam element to analyse the dynamics of fluid conveying pipes subjected to external excitation. The direction of the Coriolis force is perpendicular to the plane containing the velocity of flow vector and angular velocity vector of the pipe. Hence a three dimensional FE model is essential. This model can include curved geometry, damping, velocity and gyroscopic effects for three dimensional flexible tubes. The reduced integration used for overcoming shear locking in two node elements, will result in the formation of spurious modes leading to an incorrect prediction of natural frequencies and velocity. These modes will not occur while using three node elements. Influence of spatial as well as temporal discretisation on the time lag and frequency are also discussed. The sensitivity analysis shows that the time lag varies linearly with the mass flow rate.