Cortical implants for the blind

Arrays of stimulating electrodes can be placed in the brain itself, in the visual cortex, to bring vision to the profoundly blind. However, when designing such devices one needs to take into consideration the fact that the visual pathway maps images onto cortical structures in a complex and unpredictable way     

Growth structure investigation of MgF2 and NdF3 films grown by molecular beam deposition on CaF2(111) substrates

The growth structure of MgF₂ and NdF₃ films grown on polished CaF₂(111) substrates deposited by molecular beam deposition has been investigated using transmission electron microscopy (TEM) of microfractographical and surface replications as well as cross-sectional TEM, atomic force microscopy, packing density, and absorption measurements. It has been shown that by taking advantage of ultrahigh vacuum environments and a special stratification property of MgF₂ and NdF₃ films, the preparation of nanocrystalline films of high packing density and low optical absorption is possible at a substrate temperature of 425 K.     

Direct algorithms for data analysis in the location of sources of radiation from measured differences in distance: Model experiment

Results are presented from a model (numerical) experiment performed to check the efficiency of three groups of direct data-analysis algorithms to be used in satellite location of ground or ocean sources of radiation. The methodology behind the experiment is also explained. Translated from Izmeritel'naya Tekhnika, No. 12, pp. 40–44, December, 1996.     

Measurement of the dielectric constant of highly absorbing polar liquids at microwave frequencies

Nomograms are given for claculating the dielectric constant and dielectric loss of polar liquids by measuring the standing wave ratio for an infinitely thick layer of fluid and the layer thickness at which wave reflection is minimum. Translated from Izmeritel'naya Tekhnika, No. 2, pp. 46–47, February, 1996.     

Crack curving under mode-I loading

The whole history of failure of a rectangular panel with two symmetrical notches and a central crack subjected to a progressively increasing tension load normal to the crack plane is studied. The material of the panel exhibits substantial plastic deformation prior to fracture. An elastic-plastic analysis of the plate is first performed based on finite elements. The results of stress analysis are coupled with the strain energy density theory to determine the critical load for crack initiation and the history of stable crack growth up to the point of instability. At instability the crack runs fast through the elastic material bypassing the plastic zone near the plate boundary. The crack deviates from its initial direction and is curved even though the plate is subjected to opening-mode loading. Results for crack trajectories are given for various initial crack lengths and notch radii of the plate.Presented at Fourth Greek National Congress on Mechanics, 26–29 June 1995, held at Xanthi, Greece.     

Evaluation of a Conical Mill for Screening of Direct Compression Formulations

Suitability of a Quadro Comil^TM for screening of direct compression tablet masses was evaluated with respect to alteration of particle size distribution and blending efficiency. Air jet sieving was qualijied for determination of a particle size of spraydried lactose and microcrystalline cellulose. Using a full 3¹ × 2³ factorial design not only effects of single processing parameters (output screen size, impeller shape, velocity of the mill, and type of powder), but also their respective combinations were investigated in terms of impact on particle size and flow properties (angle of repose, bulk and tapped densities). Particle sizes before and after passing the Comil were found to be normally distributed. The results indicate that the process does not allow any of the powder characteristics studied beyond normal batch-to batch variability. This refers in particular to the proportion of fines. For evaluation of the deagglomeration effectiveness, a 2³ design was implemented with iron oxide as a model drug. Homogeneity of the blends was determined optically, and after screening twice it was found to be acceptable even with this substance, which has a particularly high agglomeration tendency, high density, and small particle size. The Quadro Comil is therefore regarded as fully suitable for deagglomeration of powders in a gentle and effective manner     

Ascitic fluid analysis in hepatocellular carcinoma

BACKGROUND: Ascites in patients with hepatocellular carcinoma (HCC) is a poorly characterized subgroup of malignancy-related ascites. Not only the underlying liver disease, but also the tumor growth and spread contributes to the ascites formation. The authors differentiated ascites in HCC from other types of ascites. METHODS: The authors analyzed the ascitic fluid of 185 consecutive patients (89 liver cirrhosis, 33 HCC, 31 peritoneal carcinomatosis, 22 liver metastases, 10 spontaneous bacterial peritonitis). RESULTS: Each subgroup showed a typical pattern. Compared with the cirrhotic patients, those with HCC showed a higher frequency of positive cytologic findings (4 of 33 versus 0/89, P < 0.004), elevated fibronectin concentration (10/33 versus 8/89, P < 0.004), and elevated polymorphonuclear cell count (10/33 versus 5/89 P < 0.004). CONCLUSIONS: A significant number of patients with ascites and HCC patients showed signs of peritoneal infiltration with positive cytologic findings and increased concentration of fibronectin. Moreover, neutrocytic ascites without signs of superinfection is relatively common (30%).     

Cyclooxygenase and lipoxygenase arachidonate metabolites synthesized by mouse peritoneal macrophages: in vitro effect of N-phenyllinoleamide from toxic oil samples

N-phenyllinoleamide (NPLA) has been detected as extraneous compound in adulterated cooking oils associated with a unique epidemic disease known as the Toxic Oil Syndrome (TOS). In this communication we report on the action of NPLA on the endogenous cyclooxygenase and lipoxygenase arachidonate metabolism. Results show that mouse peritoneal macrophages (MPM) exposed to 1 mM NPLA for 2 h undergo significant increases of 6-keto prostaglandin F1a, prostaglandin E2, leukotriene B4, 12- and 15-hydroxyeicosatetraenoic acids. MPM prelabelled with 3H-AA showed an enhanced release when exposed to NPLA. Thus, it is concluded that NPLA potentiates AA release from cell membrane phospholipids and the subsequent cyclooxygenase and lipoxygenase oxidative metabolism of this precursor to various eicosanoids. This is in agreement with the implication of peroxidative process mediated by fatty acids anilides in TOS.     

Comparison of two Varieties of Microcrystalline Cellulose as Filler-Binders II. Hydrochlorothiazide Tablets

In tests of direct-compression hydrochlorothiazide tablets prepared with either of two varieties of microcrystalline cellulose (Avicel PH 101 and Avicel PH 102), PH 102 tablets had better mechanical properties (owing to lower compressibility of mixtures and greater Interparticle bonding), while PH 101 tablets released the active principle faster. These differences are related to observed differences In tablet micropore structure.