Hydrogen reduction of chromium chlorides: A kinetic investigation

The reduction of single pellets of chromic and chromous chlorides by hydrogen has been studied kinetically. The reaction 2 CrCL₃ + H₂ →2 HCl + 2 CrCl₂ was investigated over the temperature range 475?615°C. The rate controlling factor in the range of 475?493°C. is vaporization of chromic chloride; the activation energy was found to be 67.8 K.cal./mole. Between S10 and 615°C, the reaction rate is evidently controlled by heat and internal mass transfer processes. In this case the apparent activation energy is 16.6 K.cal./mole. Reduction of chromous chloride, CrCl₂ + H₂ → 2 HCl + Cr, was investigated over the temperature range 675?800°C. This reaction is also controlled by heat and mass transfer and involves vaporization of the chromous chloride. The apparent activation energy is 25.5 K.cal./mole.     

Design and operation of an autosampler controlled flow-injection preconcentration system for lead determination by flame atomic absorption spectrometry

Flow-injection manifolds are described which allow the preconcentration of lead for flame atomic absorption determinations, using columns contained within the sample loop of an injection valve. An interface was designed which allowed the valves and pump in the system to be controlled by an autosampler which enabled precise timing of preconcentration and elution steps. The effects of sample flow rate, buffer pH and buffer type for preconcentration and eluent concentration and flow rate were investigated in order to obtain optimum performance of the system. A 50-times improvement in detection limits over conventional sample introduction was obtained for a sample volume of approximately 12 ml, preconcentrated for 150 s. The injection of eluent, as opposed to the use of a continuously flowing eluent stream, enabled this reagent to be conserved.     

Bedrock and beyond: an examination of the clinical utility of contemporary theories of female psychology

Libido theory and the idea of an innate matrix of bisexuality are an inadequate basis on which to understand female psychology. Rather, it is the mutual influence of sexuality, aggression, object relations, and a superego that inherits the object-related conflicts of early childhood, intertwined as these are with gender issues, that determine the way a woman experiences herself. A woman can have a basically confident, narcissistically valued sense of femaleness and at the same time be troubled by intense feelings of inadequacy and deprivation. Instead of arbitrarily attributing these feelings to penis envy and a sense of castration, based on the idea of bisexuality as bedrock, this paper suggests that we consider primary femininity as bedrock, but that the superego, as heir to unresolved preoedipal and oedipal object-related conflicts, functions to maintain these painful emotions. Clinical material illustrates the utility of these ideas.     

The nomenclature syndrome.

Questions the significance the term identity crisis has placed on the phenomenon of the maturing person in a changing world. The age-old endeavor to understand oneself better may not require the attention it has been receiving in the form of "new" treatment approaches. (0 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optical D-fiber-based volatile organic compound sensor

A fiber-optic sensor used to detect volatile organic compounds is described. The sensor consists of a single-mode D-fiber with a 2.5 microm polydimethylsiloxane layer. The layer is applied to the fiber flat after removal of a section of the fiber's cladding to increase evanescent interaction of the light with the layer. Absorption of volatile organic compounds into the polymer alters the refractive index of the layer, resulting in a birefringent change of the fiber. This change is observed as a shift in polarization of the light carried by the fiber. The sensor has a short length of 3 cm and a response time of around 1 s. The sensor is naturally reversible and gives an exponential response for gas and liquid concentrations of dichloromethane and acetone, respectively.     

Magnetic resonance elastography can monitor changes in medullary stiffness in response to treatment in the swine ischemic kidney

Objective

Low-energy shockwave (SW) therapy attenuates damage in the stenotic kidney (STK) caused by atherosclerotic renal artery stenosis (ARAS). We hypothesized that magnetic resonance elastography (MRE) would detect attenuation of fibrosis following SW in unilateral ARAS kidneys.

Materials and methods

Domestic pigs were randomized to control, unilateral ARAS, and ARAS treated with 6 sessions of SW over 3 consecutive weeks (n = 7 each) starting after 3 weeks of ARAS or sham. Four weeks after SW treatment, renal fibrosis was evaluated with MRE in vivo or trichrome staining ex vivo. Blood pressure, single-kidney renal-blood-flow (RBF) and glomerular-filtration-rate (GFR) were assessed.

Results

MRE detected increased stiffness in the STK medulla (15.3 ± 2.1 vs. 10.1 ± 0.8 kPa, p < 0.05) that moderately correlated with severity of fibrosis (R² = 0.501, p < 0.01), but did not identify mild STK cortical or contralateral kidney fibrosis. Trichrome staining showed that medullary fibrosis was increased in ARAS and alleviated by SW (10.4 ± 1.8% vs. 2.9 ± 0.2%, p < 0.01). SW slightly decreased blood pressure and normalized STK RBF and GFR in ARAS. In the contralateral kidney, SW reversed the increase in RBF and GFR.

Conclusion

MRE might be a tool for noninvasive monitoring of medullary fibrosis in response to treatment in kidney disease.

     

Mode purity comparison of optical vortices generated by a segmented deformable mirror and a static multilevel phase plate

We present a mode purity comparison between optical vortices (OVs) generated by a static multilevel phase plate with 16 or 32 phase steps and a vortex generated with a segmented deformable mirror with 37 actuators. Computer simulations show the intensity and phase of the vortices generated with the two methods. The deformable mirror, by being reconfigurable, shows better mode purity for high charge OVs, while the static phase plate mode efficiency declines due to the fixed number phase quantization.