Study of cold powder compaction by using the discrete element method

The discrete element method (DEM), based on a soft-sphere approach, is commonly used to simulate powder compaction. With these simulations a new macroscopic constitutive relation can be formulated. It is able to de-scribe accurately the constitutive material of powders during the cold compaction process. However, the force-law used in the classical DEM formulation does not reproduce correctly the stress evolution during the high density compaction of powder. To overcome this limitation at a relative density of about 0.85, the high density model is used. This contact model can reproduce incompressibility effects in granular media by implementing the local solid fraction into the DEM software, using Voronoi cells. The first DEM simulations using the open-source YADE software show a fairly good agreement with the multi-particle finite element simulations and experimental results.     

Aerobic selective oxidation of (hetero)aromatic primary alcohols to aldehydes or carboxylic acids over carbon supported platinum

The synthesis of substituted benzaldehydes, benzoic acids, heterocyclic aromatic aldehydes and acids has been studied via the oxidation of the aromatic alcohols with air under mild pressure (<20 bar) at 100 °C, in the presence of a 1.95 wt.% Pt/C catalyst. The solvent was found to play the most important role in determining the selectivity of the oxidation products. Changing the solvent enabled tuning the reaction either to the aldehyde (pure dioxane), or the carboxylic acid (dioxane/aqueous solution without or with addition of sodium hydroxide). This oxidation method allowed to effectively oxidize many substituted benzylalcohols with various electron-releasing or -attracting groups (NO₂, Me, OMe, Cl, Br, OH, phenyl, …) and heterocyclic alcohols including nitrogen and sulphur atoms (2-thiophenemethanol, 2- and 4-pyridine methanol compounds).     

Human and nonhuman primate lymphocytes engrafted into SCID mice reside in unique mesenteric lymphoid structures

The present study compares the location and phenotype of B lineage lymphocytes in tissues from SCID mice engrafted with PBMC of human, chimpanzee, and pig-tailed macaque origin. In mice repopulated with both human and nonhuman primate lymphocytes, plasma cells were found in the peritoneal cavity in vascularized structures located in the mesentery near the pancreas, intestines, and spleen. The predominant isotype of the plasma cells was IgG; IgM and IgA cells were also present. Kappa and lambda light chains were expressed by 62% and 38% of the Ig-containing cells, respectively. J chain expression occurred in most cells irrespective of the Ig isotype. In the SCID mice engrafted with human lymphocytes, a few IgM-containing cells were found in the spleen; plasma cells were not found in other tissues, including the intestine. The aggregation of plasma cells did not appear to be a result of infection with EBV. T cells were rarely found in the lymphoid aggregates but were recovered from the spleen and peritoneal lavage. Human Ig levels in the serum of engrafted mice reflected the isotype distribution of the cells with IgG > IgM > or = IgA.     

Some Relationships between Dyeing Kinetics of Polyester Fibres and Their Structural Changes Caused by Heat-Treatment and Dveine Conditions

The rate of dyeing of a poly (ethylene terephthalate) has been characterized as a function (a) of the tension applied before heat setting, (b) of the shrinkage allowed during heat setting, and (c) of the tension applied before dyeing. Very small variations in applied tension lead to very significant differences in rate of dyeing. Furthermore, in order to correlate the dyeing results with changes in the fibre, the structure of the polyfethylene terephthalate fibre was determined as a function of the tension applied before either heat setting or dyeing. The structural parameters studied were crystallinity, crystalline orientation, birefringence, amorphous orientation factor and water swelling at 130d?C. The variations in dyeing kinetics may be due to changes of amorphous orientation on the one hand and to changes in tortuosity, size and volume of pores on the other.     

A geometric algorithm based on tetrahedral meshes to generate a dense polydisperse sphere packing

In the discrete element method, the packing generation of polydisperse spheres with a high packing density value is a major concern. Among the methods already developed, few algorithms can generate sphere packing with a high density value. The aim of this paper is to present a new geometric algorithm based on tetrahedral meshes to generate dense isotropic arrangements of non-overlapping spheres. The method consists of first filling in every tetrahedron with spheres in contact (i.e., hard-sphere clusters). Then, the algorithm increases the packing density value by detecting the large empty spaces and filling them with new spheres. This new geometric algorithm can also generate a complex shape structure.     

A Bipolar-Selected Phase Change Memory Featuring Multi-Level Cell Storage

In this paper, a 90-nm 128-Mcell non-volatile memory based on phase-change Ge₂-Sb₂-TeB alloy is presented. Memory cells are bipolar selected, and are based on a /xtrench architecture. Experimental investigation on multi-level cell (MLC) storage is addressed exploiting the chip MLC capability. To this end, a programming algorithm suitable for 2 bit/cell storage achieving tightly placed inner states (in terms of cell current or resistance) is proposed. Measurements showed the possibility of placing the required distinct cell current distributions, thus demonstrating the feasibility of the MLC phase-change memory (PCM) storage concept. Endurance tests were also carried out. Cumulative distribu tions after 2-bit/cell programming before cycling and after 100 k program cycles followed by 1 h/150 degC bake are presented. Experimental results on MLC endurance are also provided from a 180-nm 8-Mb PCM demonstrator with the same mutrench cell structure.     

Quinazolines: combined type 3 and 4 phosphodiesterase inhibitors

A series of quinazolines has been prepared and evaluated for its ability to inhibit cyclic AMP phosphodiesterase type 3, type 4A, 4B and 4D. The most potent inhibitors showed IC50 values in the nanomolar range for type 3 and type 4 isoforms and bind with high affinity to the [3H]rolipram binding site. These quinazolines represent a new family of potent mixed PDE 3/4 inhibitors and are expected to have a therapeutic potential.     

Physician interaction with battered women: the women''s perspective

Ans raci A series of 2-(4-arylpiperazin-1-yl-methyl)-4-methyl-1-oxo-5,6,8,8a-tetrahydro -thiazolo[3,4-d] [1,2,4]triazines was prepared and tested for antinociceptive activity. The compounds were prepared by the Mannich reaction from the corresponding 2-unsubstituted thiazolotriazines. When administered intraperitoneally most were found to have potent analgesic activity in the mouse during tests of phenylbenzoquinone-induced abdominal constriction; ED50 values (doses resulting in half the maximum effect) ranged from 10 to 87 mg kg(-1). Derivatives with a 3-chloro- or 4-fluorophenylpiperazinylmethyl side-chain in the 2-position of the bicyclic system were, when administered intraperitoneally at doses greater than 25 mg kg(-1), also effective in the hot-plate test without associated sedative effects. The compounds have a large therapeutic index; intraperitoneal LD50 values (doses which result in the death of half the animals) were > 700 mg kg(-1). Naloxone attenuated the analgesic activity of the 3-chloro derivative, suggesting the participation of micro-receptors in the antinociceptive effects of this drug. In addition, a nonopioid mechanism, probably related to enhancement of the release of 5-hydroxytryptamine and noradrenaline, or inhibition of the neuronal re-uptake of these compounds, has been evinced to explain the analgesic properties of the 3-chloro or 4-fluoro derivatives. These results provide evidence for the involvement of noradrenergic and 5-hydroxytryptaminergic pathways in the analgesic activity of 3 and 4. Because of their potential effectiveness, the 3-chloro- or 4-fluorophenylpiperazinylmethyl derivatives might be suitable for treatment of a wide variety of painful conditions and could be attractive reserve agents for patients dissatisfied with opioids.