Sterile Filtration of NanoCrystal™ Drug Formulations

A Nano Crystal^TM dispersion of the iodinated x-ray contrast agent iodipamide was prepared by wet milling the drug substance in the presence of Pluronic® F127 stabilizer. The mean particle size of the formulation was 98 nm and all drug particles in the formulation were smaller than 220 nm as determined by dynamic light scattering. Approximately 1 liter of dispersion was filtered through a sterile 0.2-μm disposable capsule filter (Supor® 200 DCF^TM, 0.I m² effective filtration area [EFA], Gelman Sciences) to condition the capsule. No drug concentration or size distribution changes were detected after the filtration process. The microbiological validation tests were performed using Pseudomonas diminuta organisms to challenge the capsule under simulated worst-case process conditions. The results showed that the Supor 200 DCF was able to retain 100% Pseudomonas diminuta organisms (≥10⁷ organisms per cm² of effective filtration area). Thus, this study demonstrated that terminal filtration is a feasible process to sterilize Nano Crystal^TM drug dispersions that may be chemically or physically unstable at elevated temperatures and thus not amenable to terminal heat sterilization.     

Nonlinear Modeling of Flexible Cable Loads on Large Sheaves

Stress analysis of the components of a sheave used to transfer loads between the lift span and counterweight in a movable span bridge is investigated. Stress analysis is a requirement for properly designing such sheaves. Modeling of the mechanism of load transfer from the wire ropes to the sheave is accomplished in three ways: (1) the traditional manner using a uniform pressure distribution; (2) using a varying pressure distribution developed from belt/pulley theory; and (3) using the finite-element method with nonlinear contact elements between the wire rope and the sheave. Internal stresses in the sheave are calculated using uniform distributed pressure and a varying pressure distribution. It is determined that the load distribution on the sheave from the wire ropes is precisely the same for the nonlinear contact analysis and the belt/pulley analysis. The internal stress analysis results show that the traditional, uniformly distributed load representation is less conservative than the more realistic belt/pulley load representation. A methodology is developed that can be utilized to more accurately model the load transfer representation without the complexity of nonlinear analyses.     

Probing the reaction pathway of dehydrogenation of the LiNH2 + LiH mixture using in situ H NMR spectroscopy

Using variable temperature in situ ¹H NMR spectroscopy on a mixture of LiNH₂ + LiH that was mechanically activated using high-energy ball milling, the dehydrogenation of the LiNH₂ + LiH to Li₂NH + H₂ was investigated. The analysis indicates NH₃ release at a temperature as low as 30 °C and rapid reaction between NH₃ and LiH at 150 °C. The transition from NH₃ release to H₂ appearance accompanied by disappearance of NH₃ confirms unambiguously the two-step elementary reaction pathway proposed by other workers.     

An approach to systems verification

The term systems verification refers to the specification and verification of the components of a computing system, including compilers, assemblers, operating systems and hardware. We outline our approach to systems verification, and summarize the application of this approach to several systems components. These components consist of a code generator for a simple high-level language, an assembler and linking loader, a simple operating system kernel, and a microprocessor design.     

A Version Space Approach to Learning Context-free Grammars

In principle, the version space approach can be applied to any induction problem. However, in some cases the representation language for generalizations is so powerful that (1) some of the update functions for the version space are not effectively computable, and (2) the version space contains infinitely many generalizations. The class of context-free grammars is a simple representation that exhibits these problems. This paper presents an algorithm that solves both problems for this domain. Given a sequence of strings, the algorithm incrementally constructs a data structure that has nearly all the beneficial properties of a version space. The algorithm is fast enough to solve small induction problems completely, and it serves as a framework for biases that permit the solution of larger problems heuristically. The same basic approach may be applied to representations that include context-free grammars as special cases, such as And-Or graphs, production systems, and Horn clauses.     

The social class-related experiences of men: Integrating theory and practice.

When a man loses the ability to be the "breadwinner," what types of conflicts does he experience? More important, how can counselors understand the full depth of his concerns if social class is not explored? However, the extant literature on social class and counseling applications is meager. Hence, the author explains the social class worldview model and modern classism theory as frameworks to understand subjective social class experiences. Although the models are theoretical, the author provides case vignettes to illustrate how clinicians can gather and interpret social class information and integrate it into client profiles and treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

如何面对城市消费者

我们的父辈、祖辈甚至是几代以前，居民从农村回到城市的人口的反向迁移，如今全部都记录在案。     

Synthesis, densification, and mechanical properties of TaB2

Tantalum diboride (TaB₂) was synthesized by reducing Ta₂O₅ using B₄C and graphite at 1600 °C under flowing Ar. The powder had an average particle size of 0.4 μm with both needle-like and rounded particles. The TaB₂ powder was hot pressed to relative densities of 97% at 2000 °C (3.6 μm grain size) and 98% at 2100 °C (5.3 μm grain size). Mechanical properties were measured for TaB₂ hot pressed at 2100 °C and were comparable to those of the commonly studied diborides, ZrB₂ and HfB₂. The Young's modulus was 551 GPa, Vickers' hardness was 25.6 GPa, flexure strength was 555 MPa, and fracture toughness was 4.5 MPa-m^1/2.