Spinning of poly(ethylene terephthalate) fibers from a melt pool without a spinneret

Monofilament fibers were spun continuously from the free surface of a pool of molten poly(ethylene terephthalate) without the aid of a spinneret. For take-up velocities in the range of 12 to 400 ft/min, the denier of the filaments produced was an inverse power function of take-up velocity, and the birefringence was an inverse power function of the filament diameter. Production rate and product uniformity were strongly dependent on take-up velocity and surface temperature of the melt pool.     

An Automated Dual-Wavelength Spectrophotometer Optimized for Phytochrome Assay

ABSTRACT

A microcomputer-controlled dual-wavelength spectrophotometer suitable for automated phytochrome assay is described. The optomechanical unit provides for sequential irradiation of the sample by the two measuring wavelengths with intervening dark intervals and for actinic irradiation to inter-convert phytochrome between its two forms. Photomultiplier current is amplified, converted to a digital value and transferred into the computer using a custom-designed IEEE-488 bus interface. The microcomputer calculates mathematically both absorbance and absorbance difference values with dynamic correction for photomultiplier dark current. In addition, the computer controls the operating parameters of the spectrophotometer via a separate interface. These parameters include control of the durations of measuring and actinic irradiation intervals and their sequence. Because the data are processed solely within the microcomputer, except for the initial linear amplification, any output desired can be obtained, including automated determination of not only total phytochrome content, but also of the proportions present in the far-red- and red-absorbing forms.     

Drug use and validity of substance use self-reports in veterans seeking help for posttraumatic stress disorder.

The present study assessed drug use and the validity of self–reports of substance use among help–seeking veterans referred to a specialty clinic for the assessment of posttraumatic stress disorder (PTSD). Patients (n?=?341) were asked to provide a urine sample for use in drug screening as part of an evaluation of PTSD. Self–reports of substance use were compared with same–day supervised urine samples for 317 patients who volunteered to participate in a drug screening. Results suggested that self–reports were generally quite valid. Only 8% of the cases involved patients not reporting substance use detected by urine screens. A total of 42% of the participants were identified as using drugs of abuse (excluding alcohol) through self–report and urine drug screens. Among participants using drugs, PTSD diagnosis was significantly associated with greater marijuana and depressant use as compared with stimulant (cocaine and amphetamines) use. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Si-implantation activation annealing of GaN up to 1400°C

Implant activation annealing of Si-implanted GaN is reported for temperatures from 1100 to 1400°C. Free electron concentrations up to 3.5×10²⁰ cm⁻³ are estimated at the peak of the implanted profile with Hall mobilities of ∼60 cm²/Vs for annealing at 1300°C for 30 s with an AIN encapsulant layer. This mobility is comparable to epitaxial GaN doped at a similarly high level. For annealing at ≥1300°C, the sample must be encapsulated with AIN to prevent decomposition of the GaN layer. Channeling Rutherford backscattering demonstrates the partial removal of the implant damage after a 1400°C anneal with a minimum channeling yield of 12.6% compared to 38.6% for the as-implanted spectrum. Scanning electron microscope images show evidence of decomposition of unencapsulated GaN after a 1300°C anneal and complete sublimation after 1400°C. The use of AIN encapsulation and annealing at temperatures of ∼1300°C will allow the formation of selective areas of highly doped GaN to reduce the contact and access resistance in GaN-based transistors and thyristors.     

Weight regulation with palatable food and liquids in rats with lateral hypothalamic lesions.

Maintained 25 female Carworth CFE albino rats with 4- or 7-sec 1-ma bilateral lesions of the lateral hypothalamus (LH) for 87 days on a high-fat diet and a sequence of fluids (water, 6% sucrose, and 1 or .2% saccharin). Lesioned Ss reached a greater weight than 9 sham-lesioned Ss offered the same diet and fluids, and maintained greater weight regardless of the fluid offered. These data do not support the hypothesis that LH lesions lower the set point for weight. Rather, the finickiness of LH Ss results in smaller intake of unpalatable foods and water which, in turn, results in stablization of weight below that of controls. If sufficiently hydrated, LH Ss eat greater quantities of highly palatable foods than do controls, resulting in greater body weight. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanism mobility and a local dimension test

The mobility of a mechanism is the number of degrees of freedom (DOF) with which it may move. This notion is mathematically equivalent to the dimension of the solution set of the kinematic loop equations for the mechanism. It is well known that the classical Grübler-Kutzbach formulas for mobility can be wrong for special classes of mechanisms, and even more refined treatments based on displacement groups fail to correctly predict the mobility of so-called “paradoxical” mechanisms. This article discusses how recent results from numerical algebraic geometry can be applied to the question of mechanism mobility. In particular, given an assembly configuration of a mechanism and its loop equations, a local dimension test places bounds on the mobility of the associated assembly mode. A publicly available software code makes the idea easy to apply in the kinematics domain.     

First tests of diagnostic mirrors in a tokamak divertor: An overview of experiments in DIII-D

Mirrors will be used in ITER in all optical diagnostic systems observing the plasma radiation in the ultraviolet, visible and infrared ranges. Diagnostic mirrors in ITER will suffer from electromagnetic radiation, energetic particles and neutron irradiation. Erosion due to impact of fast neutrals from plasma and deposition of plasma impurities may significantly degrade optical and polarization characteristics of mirrors influencing the overall performance of the respective diagnostics. Therefore, maintaining the best possible performance of mirrors is of the crucial importance for the ITER optical diagnostics. Mirrors in ITER divertor are expected to suffer from deposition of impurities. The dedicated experiment in a tokamak divertor was needed to address this issue. Investigations with molybdenum diagnostic mirrors were made in DIII-D divertor. Mirror samples were exposed at different temperatures in the private flux region to a series of ELMy H-mode discharges with partially detached divertor plasmas. An increase of temperature of mirrors during the exposure generally led to the mitigation of carbon deposition, primarily due to temperature-enhanced chemical erosion of carbon layers by D atoms. Finally, for the mirrors exposed at the temperature of ∼160 °C neither carbon deposition nor degradation of optical properties was detected.     

Search for New Superconductors: an Electro-Magnetic Phase Transition in an Iron Meteorite Inclusion at 117 K

The discovery of superconductivity in pnictides and iron chalcogenides inspires the search for new iron-based superconducting phases. Iron-rich meteorites present a unique opportunity for this search because they contain a broad range of compounds produced under extreme growth conditions. We investigated a natural iron sulfide-based material (troilite) inclusion with its associated minerals in the iron meteorite (Fe, Ni), Tlacotepec. Tlacotepec cooled over the course of 10 ⁶–10 ⁷ years in an asteroidal core under high pressure while insoluble sulfur-rich materials segregated into inclusions within the Fe–Ni core, synthesizing minerals under conditions not possible in the laboratory. The search for superconductivity in these heterogeneous materials requires a technique capable of detecting minute amounts of a superconducting phase embedded in a non-superconducting matrix. We used magnetic field modulated microwave spectroscopy (MFMMS), the most sensitive, selective, and non-destructive technique, to search for superconductivity in heterogeneous systems. Here, we report the observation of an electro-magnetic phase transition (EMPT) at 117 K that produces a unique MFMMS response. A pronounced and reproducible peak proves the appearance of an EMPT at 117 K. The temperature of this transition is not influenced by moderate magnetic fields up to 1400 Oe. Further, hysteretic isothermal field sweep loops are typical of the field sweep loops caused by flux trapping in high T _c superconductors. Although the compound responsible for the peak in the MFMMS spectra was not identified, our results indicate that it is a material heterogeneously distributed over the inclusion and possibly an iron sulfide-based phase.