Zeolite synthesis from paper sludge ash with addition of diatomite

BACKGROUND: This study aimed to investigate the synthesis of zeolites from paper sludge ash (PSA) with added diatomite to remove both NH₄⁺ and PO₄^3? for water purification. The PSA had low Si and significant Ca contents. Four types of diatomite: white (T‐W) and brown (T‐B) from deposits of marine origin in Takanosu, and white (S‐W) and gray (S‐G) from lacustrine deposits in Shonai, were added to NaOH solution to increase the Si content and thereby synthesize zeolites with high cation exchange capacity (CEC). RESULTS: The order of the amounts of Si extracted from the diatomite to the alkali solution was S‐W > T‐W = T‐B > S‐G, which correlates with the amorphous SiO₂ content of diatomite. The original ash without addition of diatomite yielded hydroxysodalite with CEC of about 1.0 mmol g^?1. For all samples, the addition of diatomite to the solution yielded zeolite‐P with a higher CEC, but the addition of excess Si inhibited the synthesis of zeolite‐P, and the CEC of the product was low. A product with high CEC including zeolite‐P was obtained in a solution with around 500 mmol L^?1 of Si concentration, and had the ability to remove both NH₄⁺ and PO₄^3?. CONCLUSION: Diatomite has the potential for used as an additive for the synthesis of high CEC zeolite from PSA. The product with zeolite‐P exhibited relatively high CEC, capacity for NH₄⁺ uptake, and the ability to remove PO₄^3? by precipitation, which is preferable for water purification applications. Copyright © 2008 Society of Chemical Industry     

测井相识别模型及其在东海油气勘探中的应用

文章提出一种测井相识别模型,该模型用常规测井信息,定量地确定测井相在钻遇地层中的空间位置,建立测井相。配合东海油气勘探工作,用该识别模型对苏堤构造带的钻遇地层进行了测井相分析。     

Material removal and surface damage in EDM of Ti3SiC2 ceramic

Material removal and surface damage of Ti₃SiC₂ ceramic during electrical discharge machining (EDM) were investigated. Melting and decomposition were found to be the main material removal mechanisms during the machining process. Material removal rate was enhanced acceleratively with increasing discharge current, i_e, working voltage, u_i, but increased deceleratively with pulse duration, t_e. Microcracks in the surface and loose grains in the subsurface resulted from thermal shock were confirmed, and the surface damage in Ti₃SiC₂ ceramic led to a degradation of both strength and reliability.     

轮式工程机械轮边减速器优化模型与方法

论述了重构轮式工程机械轮边减速器优化设计数学模型的必要性,给出了精确化的目标函数,全面化和准确化的设计变量、基于并行设计的约束条件;介绍了对优化解适用性评价的方法和手段。巧妙地解决了优化解中离散变量的圆整问题,提供了基于MATLAB的求解反渐开线函数的M文件。     

大学教学价值取向的生存论反思

在生存论看来，以实存论为基底的大学教学价值取向，遗忘了追问人的生存意义。实际上，生存意义是在欲、技、道的游戏中生成的。大学教学价值向“寻求意义”的转向，实质上是“理智培育”、“技术培训”、“情感培养”三类传统价值取向在当代的共同表现形式．而非彼此对立。     

水上地震折射互换法误差分析

在理论上，用源检互换的方法进行折射地震勘探是没有误差的，在某些特殊条件下无法铺设检波器而又必须进行折射地震勘探时它也是唯一的选择，然而，在实际工作中，由于各种因素的影响，其误差是不可忽略的。为此，本文从地震折射运动学的角度对水上地震折射互换法因过河钢丝绳的重量、水的流速和流向、炮点深度等客观因素造成的解释误差进行了分析，揭示了水上地震折射互换法应注意的问题。这对水上地震折射互换法的资料解释进行误差校正提供了理论基础。     

钢纤维聚合物混凝土抗压本构关系

钢纤维聚合物混凝土是由聚合物混凝土基体和钢纤维共同组成的纤维增强复合材料，它的力学行为不仅依赖于聚合物混凝土基体的行为，而且与钢纤维的掺量、分散特征以及钢纤维的几何尺寸有关，本文将基于损伤力学原理研究在不同纤维掺量下的钢纤维聚合物混凝土的全程压力-应变曲线及其本构模型。     

Potentiometric studies of oxidation–reduction reactions with redox copolymers

Polymeric oxidants in the bead form that were macroporous styrene/divinylbenzene copolymers containing N‐chlorosulfonamide functional groups (in sodium or hydrogen form) or N‐bromosulfonamide groups (in sodium form) were synthesized and investigated to determine their oxidizing powers. The redox potentials of the N‐chlorosulfonamide/sulfonamide and N‐bromosulfonamide/sulfonamide systems were determined by potentiometric studies at different pH values with aqueous solutions of Na₂SO₃, KCN, and KSCN as reducers. The formal redox potentials of the N‐chlorosulfonamide copolymers were 0.79, 0.44, and ?0.12 V at pH's of 1.8, 8.45, and 13.6, respectively. The formal redox potential of the N‐bromosulfonamide copolymer was about 100 mV higher in comparable conditions and in solutions over pH = 5 (e.g., 0.56 V at pH = 8.56). The comparatively higher oxidizing power of the N‐bromosulfonamide copolymer was particularly evident in a strong alkaline medium (in which the N‐chlorosulfonamide copolymer was not reactive). In contrast, the N‐chlorosulfonamide copolymer showed strong oxidative properties in acidic media (in which the N‐bromosulfonamide copolymer decomposed itself). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

On the microhardness testing of electrically stressed poly(phenylene oxide): Polystyrene blends

Microhardness measurements have been performed on untreated (virgin) and electrically stressed, solvent‐cast laboratory‐prepared samples of pure poly(phenylene oxide) (PPO), pure polystyrene (PS), and PPO : PS polyblends with different weight proportions. Results of such measurement on untreated polyblend sample show that microhardness (H_v) increases with increase in the content of PS up to 10 wt %, which attributed to the existence of homogeneous phase morphology. However, this feature is not observable in samples containing higher content of PS. Electrical stress is found to modify considerably the mechanical property of polymer. The effect of electric field on the microhardness of such samples (PPO : PS :: 90 : 10) has been characterized by the existence of a peak. Trapping of charge carriers in electrically stressed samples imparts hardening to the polyblend up to an applied step field of 190 kV/cm. However, the excessive charging beyond this step field value destroys this characteristic. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Nondegradative microextrusion of resorbable polyesters for pharmaceutical and biomedical applications: The cases of poly‐lactic‐acid and poly‐caprolactone

In recent years biodegradable polymers, particularly polyesters such as the poly(lactic acid) (PLA) and polycaprolactone (PCL), have gained high interests for their applicability in the biomedical and pharmaceutical fields where they're used for manufacturing various different resorbable devices, from tissue engineering scaffolds to controlled drug release systems. Despite many positive characteristics, processability of these materials still remains a critical issue as they easily tend to degrade during manufacturing. In this article we aimed to assess microextrusion as a nondegradative process for manufacturing PLA and PCL. The results we experimentally obtained, that are hereby presented, set a new point in the on‐going debate on degradation during processing of resorbable polymers as they allow to affirm that microextrusion leaves unmodified molecular weight distributions without producing any evident reductions in mean molecular weight. Microextrusion thus represents a risk‐free high molecular weight polymer processing solution for obtaining nondegraded products within pharmaceutical and biomedical production lines, such as for scaffolds for tissue engineering applications or drug delivery. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008