Sharp Loss Research Articles

An Interesting Cecal Mass in a Patient with AIDS

FigurePurpose: Disseminated histoplasmosis is a common opportunistic infection in AIDS patients who are severely immunocompromised. Gastrointestinal histoplasmosis (GIH) generally occurs in association with disseminated histoplasmosis or rarely as localized lesions. GIH is defined by radiological or endoscopic findings in conjunction with positive gastrointestinal tissue cultures or histopathologic observation of broad budding yeasts of H. capsulatum in tissue specimens. GIH typically occurs with median CD4 counts of 35 and patients naïve to anti-retroviral therapy. Common clinical features include fever, abdominal pain and diarrhea. Colon is the most frequently affected site (67%) followed by the cecum (17%). Endoscopic findings of GIH are usually multiple ulcers or pseudopolyps; however it can rarely present as a mass or constricting lesion suspicious for malignancy. We describe a case of a 45-year-old white male with history of hemophilia A and AIDS. Patient was admitted to us with a three week history of sharp right lower quadrant abdominal pain and weight loss. Patient had no history of opportunistic infection and was naïve to anti-retroviral therapy. On physical examination, the right lower quadrant was tender to palpation with voluntary guarding. Laboratory examination revealed a CD4 count of 17/μL. A computed tomography (CT) scan of his abdomen showed a non-obstructing cecal mass with an ‘apple-core’ appearance highly suspicious for malignancy (marked by white arrow in Fig. 1). Subsequent colonoscopy showed multiple small ulcers in the cecum, ascending colon and the transverse colon with a three centimeter mass in the cecum (Fig. 2). Histopathology of the ulcers and the mass showed numerous intracellular budding yeasts consistent with H. capsulatum. Patient was started on itraconazole and reported resolution of abdominal pain during an outpatient follow-up after a three week period.[figure1][figure2]Figure

Titanium phosphonate-supported palladium catalyst for the hydrogenation of acetophenone with one-phase catalysis and two-phase separation

Abstract A novel inorganic polymer titanium 2-[ N -(2-hydroxy-1,2-diphenylethyl)]aminoethylphosphate (TiP) and its supported palladium complex (TiP–Pd) had been synthesized and characterized by IR, XPS, XRD, TG, SEM and TEM. The catalyst TiP–Pd was applied to the catalytic hydrogenation of acetophenone in homogeneous ethanol phase and can be conveniently recovered with above 97% recovery by adding equal volume of petroleum ether. In the catalytic hydrogenation of acetophenone, the selectivities to 1-phenylethanol and ethylbenzene was up to 93.3% at −20 °C and 100% at −20 to 40 °C, respectively under atmospheric hydrogen pressure. The catalyst TiP–Pd can be reused 11 times without the leaching of palladium ion and the sharp loss of catalytic activity.

Trypanosoma cruzi: Attenuation of virulence and protective immunogenicity after monoallelic disruption of the cub gene

Calmodulin–ubiquitin ( cub) is a single-copy gene of Trypanosoma cruzi, which encodes a 208 aminoacid polypeptide of unknown function, containing putative calcium-binding domains. After targeted deletion, a clone (TulCub8) was derived where one of the two alleles was disrupted. This clone displayed a sharp and stable loss of virulence for mice. Parasitemias after inoculation of 10 6 trypomastigotes of the mutant, as compared to wild-type parasites were 68-fold lower ( p = 0.018) in adult Swiss mice and 27-fold lower ( p = 0.002) in newborn Balb/c mice. Epimastigote inocula of the mutant were strongly protective against infection by wild-type parasites. Virulence was not restored by serial passage in mice, showing that the attenuated phenotype is stable and gene-conversion from the intact cub allele does not occur at an appreciable rate. Retransfection of the missing cub allele restored virulence. Complementation experiments showed that the intact cub gene is necessary for full expression of virulence.

Probabilistic Error Diffusion For Image Enhancement

This paper presents a stochastic error diffusion approach and analyzes its effect on image quality and artifacts. Unlike traditional error diffusion techniques that use fixed or image- dependent error diffusion weights, stochastic error diffusion distributes image quantization errors to neighboring pixels based on a stochastic process whose expectation and entropy are controllable. A model is provided to derive diffusion weight expectations based on the principle of uniform error propagation . The paper empirically compares the difference between random quantization thresholds and random diffusion weights and shows that stochastic error diffusion, unlike random dithering, does not generally produce images of degraded quality. On the contrary, by selecting appropriate expectation and entropy for diffusion weights, stochastic error diffusion may drastically reduce image noise patterns with little loss of image sharpness.

Studies on the structural, thermal and optical behaviour of solution grown organic NLO material: 8‐hydroxyquinoline

AbstractSingle crystal of 8‐hydroxyquinoline (8HQ) having chemical formula C9H7NO, an organic nonlinear optical (NLO) material has been successfully grown by slow evaporation solution growth technique at room temperature. The crystal system has been confirmed from the powder X‐ray diffraction (PXRD) analysis. The crystalline perfection was evaluated by high resolution X‐ray diffractometry (HRXRD). From this analysis we found that the quality of the crystal is quite good. However, a very low angle (tilt angle 14 arc sec) boundary was observed which might be due to entrapping of solvent molecules in the crystal during growth. Its optical behavior has been examined by UV‐Vis. analysis, which shows the absence of absorbance between the wavelengths ranging from 400 to 1200 nm. From the thermal analysis it was observed that the material exhibits single sharp weight loss starting at 113°C without any degradation. The laser damage threshold was measured at single shot mode and the SHG behavior has been tested using Nd:YAG laser as a source. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Structural, thermal and spectroscopic properties of supramolecular coordination solids

Molecules in metal isonicotinate tetrahydrates, M(NC5H4-p-CO2)2.4H2O with M = Mn, Fe, Co, Ni, Cu, Zn, consisting of the hexacoordinate complexestrans-[M(NC5H4-p-CO2)(OH2)4], participate in exhaustive hydrogen-bond formation among themselves to lead to a robust 3D supramolecular network in the solid state. Solid-state diffuse reflectance UV-Vis-NIR spectra of the complexes have been assigned to ligand field and charge transfer transitions. Sharp weight loss due to dehydration, as shown by TGA of Cu(NC5H4-p-CO2)2.4H2O, suggests the suitability of this complex for the gravimetric estimation of copper.

Studying the effect of environmental variables on the genotype × environment interaction of tomato

Genotype × environment interaction (GEI) affects marketable fruit yield and average fruit weight of both hybrid and open-pollinated (OP) tomato genotypes. Cultivars vary significantly for marketable fruit yield, with hybrid cultivars having, on average, higher yield than OP cultivars. However, information is scanty on environmental factors affecting the differential response of tomato genotypes across environments. Hence, the aim of this research was to use factorial regression (FR) and partial least squares (PLS) regression, which incorporate external environmental and genotypic covariables directly into the model for interpreting GEI. In this research, data from an FAO multi-environment trial comprising 15 tomato genotypes (7 hybrid and 8 OP) evaluated in 18 locations of Latin America and the Caribbean were analyzed using FR and PLS. Environmental factors such as days to harvest, soil pH, mean temperature (MET), potassium available in the soil, and phosphorus fertilizer accounted for a sizeable portion of GEI for marketable fruit yield, whereas trimming, irrigation, soil organic matter, and nitrogen and phosphorus fertilizers were important environmental covariables for explaining GEI of average fruit weight. Locations with relatively high minimum and mean temperatures favored the marketable fruit yield of OP heat-tolerant lines CL 5915-223 and CL 5915-93. An OP cultivar (Catalina) and a hybrid (Apla) showed average marketable fruit yield across environments, while two hybrids (Sunny and Luxor) exhibited outstanding marketable fruit yield in high yielding locations (due to lower temperatures and higher pH) but a sharp yield loss in poor environments. Two stable hybrid genotypes in high yielding environments, Narita and BHN-39, also showed high and stable yield in average and low yielding environments.

Spin-polarized electron energy loss spectroscopy on Fe(100) thin films grown onAg(100)

We report sharp spin-dependent energy loss features in electron scattering frombcc Fe(100) thin films grown on Ag(100). Majority spin features are observed at∼1.8 and 2.5 eV energy loss, and a minority spin feature is observed at∼2.0 eV energy loss. The majority spin peaks are attributed to spin-flip exchange scatteringfrom the Fe films. The minority spin peak is attributed to non-flip exchange scattering withan energy corresponding to the separation between occupied and unoccupied minority spinbands. The observed peak energies compare favourably with electronic structurecalculations for Fe and with spin-resolved photoemission and inverse photoemission results.

Synthesis and Characterization of Mixed‐Metal Oxide Nanopowders Along the CoOx–Al2O3 Tie Line Using Liquid‐Feed Flame Spray Pyrolysis

We report here the use of liquid‐feed flame spray pyrolysis (LF‐FSP) to produce a series of nanopowders along the CoOx–Al2O3 tie line. The process is a general aerosol combustion synthesis route to a wide range of lightly agglomerated oxide nanopowders. The materials reported here were produced by aerosolizing ethanol solutions of alumatrane [Al(OCH2CH2)3N] and a cobalt precursor, made by reacting Co(NO3)2·6H2O crystals with propionic acid. The compositions of the as‐produced nanopowders were controlled by selecting the appropriate ratios of the precursors. Nine samples with compositions (CoO)y(Al2O3)1−y, y=0−1 along the CoOx–Al2O3 tie line were prepared and studied. The resulting nanopowders were characterized by X‐ray fluorescence, BET, scanning electron microscopy, high‐resolution transmission electron micrographs, X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and FTIR. The powders typically consist of single‐crystal particles <40 nm diameter and specific surface areas (SSAs) of 20–60 m2/g. XRD studies show a gradual change in powder patterns from δ‐Al2O3 to Co3O4. The cobalt aluminate spinel phase is observed at stoichiometries (21 and 37 mol%) not seen in published phase diagrams, likely because LF‐FSP processing involves a quench of >1000°C in microseconds frequently leading to kinetic rather than thermodynamic products. Likewise, the appearance of Co3O4 rather than CoO as the end member in the tie line is thought to be a consequence of the process conditions. TGA studies combined with diffuse reflectance FTIR spectroscopic studies indicate that both physi‐ and chemi‐sorbed H2O are the principal surface species present in the as‐processed nanopowders. The only sample that differs is Co3O4, which has some carbonate species present that are detected and confirmed by a sharp mass loss event at ∼250°C. The thermal behavior of the high cobalt content samples differs greatly from the low cobalt content samples. The latter behave like most LF‐FSP‐derived nanopowders exhibiting typical 1%–4% mass losses over the 1400°C range due mostly to loss of water and some CO2. The high cobalt content samples exhibit a sharp mass loss event that can be attributed to the decomposition of Co3O4 to CoO.

Structure, thermal analysis and magnetism of the doubly bridged linear polymer [Ni(4-NH 2-C 6H 4CO 2) 2(CH 3OH) 2] · CH 3OH

The title compound [Ni(4-NH 2-C 6H 4CO 2) 2(CH 3OH) 2] · CH 3OH ( 1) consists of Ni(II) atoms doubly bridged by p-aminobenzoate ligands (PAB) into 1D chains which are further connected into a 3D framework by methanol molecules through hydrogen bonding. Compound 1 is monoclinic P2(1)/ n, a = 9.0903(5) Å, b = 10.9059(5) Å, c = 9.9994(5) Å, β = 106.6880(10)°, Z = 4. Intrachain π–π interactions are observed between the aromatic rings of doubly bridging PAB ligands. The aromatic rings are in an offset arrangement with 3.607 Å interplanar spacing. The magnetic data of compound 1 for the temperature range 300–3 K is indicative of ferromagnetically coupled nickel species. The best fitting parameters were obtained for J = 0.74 cm −1, D = −2.48 cm −1 and g = 2.35. Thermogravimetric analysis of 1 indicates a sharp weight loss of one PAB ligand centered at 387.42 °C (Δ H = 94.86 kJ/mol) and a loss of two coordinated methanol molecules at 489.20 °C with Δ H = 29.78 kJ/mol. The formation constant of Ni(II) with p-aminobenzoic acid has been evaluated at different temperatures using pH titration techniques in 50% ethanol. The obtained values at 25 °C are log K f1 = 3.24 and log K f2 = 1.21. The thermodynamic parameters of complexation were also calculated and discussed.

Fabrication and characterization of permeable degradable poly( dl-lactide- co-glycolide) (PLGA) hollow fiber phase inversion membranes for use as nerve tract guidance channels

Biodegradable permeable poly( dl-lactide- co-glycolide) (PLGA) hollow fiber membranes (HFMs) were fabricated using a wet phase inversion technique. By varying several parameters, such as the spinneret size, solvent and non-solvent pair, polymer concentration, flow rate, precipitation method, drop height, and small molecular pore-forming agents, PLGA HFMs with variable sizes, surface morphologies, porosities, and diffusive permeability were obtained. Under simulated physiological conditions in vitro, PLGA HFMs exhibited a degradation profile to accommodate nervous system regeneration and axonal outgrowth. While accelerated degradation resulted in substantial molecular weight loss starting at 2 weeks and loss of selective permeability at 3 weeks, PLGA HFMs maintained gross structural integrity in the first 4 weeks, followed by sharp weight loss at 6 weeks and complete disappearance at about 8 weeks. When compared to the raw PLGA material in a pellet form, which underwent heterogeneous degradation, the PLGA HFMs exhibited a homogeneous degradation where the surface and bulk degraded at approximately the same rate, and an overall lower degradation rate. Our results indicate that using a wet phase inversion technique, degradable HFMs with variable size, inner and outer surface morphologies, porosity, and permeability with potential applications for nerve tract guidance conduits can be fabricated.

A shape-selective catalyst for epoxidation of cyclic olefins: The nanoporous nickel phosphate VSB-5

Nickel in the form of porous nickel phosphate VSB-5 has been used as a shape-selective catalyst for epoxidation of cyclic olefins such as cyclohexene and cyclooctene using hydrogen peroxide. The VSB-5 showed high selectivity to cyclohexene oxide and cyclohexane diol, much higher productivity per catalyst weight in the epoxidation of cyclohexene, and high selectivity to cyclooctene oxide in the epoxidation of cyclooctene. The VSB-5 behaved as a heterogeneous catalyst in the epoxidation and can be used many times without structure degradation, leaching of active nickel species, or significant activity loss. It has been concluded that the epoxidation reaction with VSB-5 proceeds via a free-radical mechanism by taking into consideration a sharp activity loss in the presence of a radical scavenger, hydroquinone. The effect of radical scavengers with different molecular dimension on the catalytic activity also indicates the shape selectivity in the pores of VSB-5.

Thermal decomposition of hydronium jarosite (H3O)Fe3(SO4)2(OH)6

Thermogravimetry combined with mass spectrometry has been used to study the thermal decomposition of a synthetic hydronium jarosite. Five mass loss steps are observed at 262, 294, 385, 557 and 619°C. The mass loss step at 557°C is sharp and marks a sharp loss of sulphate as SO3 from the hydronium jarosite. Mass spectrometry through evolved gases confirms the first three mass loss steps to dehydroxylation, the fourth to a mass loss of the hydrated proton and a sulphate and the final step to the loss of the remaining sulphate. Changes in the molecular structure of the hydronium jarosite were followed by infrared emission spectroscopy. This technique allows the infrared spectrum at the elevated temperatures to be obtained. Infrared emission spectroscopy confirms the dehydroxylation has taken place by 400 and the sulphate loss by 650°C. Jarosites are a group of minerals formed in evaporite deposits and form a component of the efflorescence. The minerals can function as cation and heavy metal collectors. Hydronium jarosite has the potential to act as a cation collector by the replacement of the proton with a heavy metal cation.

Distribution and properties of catalytically active Cu 2+-sites on a mesoporous MCM-41 silicate modified by Al, Zr, W, B, or P ions

Pure SiO 2 having a MCM-41 structure was modified by the introduction of 1 mmol/g of Al, Zr, W, B, or P. The parent silica and the modified materials were used to support a dispersed cupric oxide. The distribution, properties and thermal stability of the catalytic Cu 2+-active sites were examined by ESR and IR spectroscopy and by measuring the activity in a test reaction of ethane oxidation. Modification of the parent silica MCM-41 influences drastically the stabilization of isolated Cu 2+-species. Al-MCM-41 provides the most disperse (70–80%) and thermally stable state of the cupric phase. However, no simple correlation exists between the total number of surface Cu 2+-sites and the catalytic activity. The specific catalytic activity (per one Cu 2+-active site accessible to the reactants) depends strongly on the structure of the localized site. Isolated Cu 2+-sites grafted to Al-MCM-41 show relatively high activity for the sample calcined at 520 °C. Thermal treatment at 650–750 °C causes a sharp loss of specific Cu 2+ catalytic activity of Cu/Al-MCM-41 (as is also the case with CuH-ZSM-5). The less disperse cupric phase in non-modified MCM-41 demonstrates a higher specific catalytic activity.

HTS Narrow Band Filters at UHF Band for Radio Astronomy Applications

High performance narrow-band High-Temperature Superconductor (HTS) filters at 610 MHz with very sharp cut-off response and low loss are needed for improving the observation of pulsars at the Jodrell Bank Observatory, UK. An eight-pole quasi-elliptic HTS filter using compact resonators has been designed for this purpose. The measured response of filter has an insertion loss of 0.3 dB (including a 0.2 dB ripple), and a return loss of 15 dB in the passband. Two transmission zeroes are realized to improve the steepness of the cut-off. The lowest harmonic is designed to appear at 1.79 GHz, about three times the center frequency. The out-of-band rejection is better than 85 dB up to this harmonic. The filter has been tested in the observatory with excellent results.

Phytotoxic effects of trichloroacetic acid on Scots pine and birch determined by chl a fluorescence and the JlP-test

Trichloroacetic acid (TCA) is a phytotoxic substance that, until the 1980s was used in the form of sodium trichloroacetate (TCA-Na) as a herbicide in agriculture and forestry. Since then it has been banned almost everywhere in Europe and in many other countries in the world. Although much has been learned about the natural and anthropogenic sources of TCA over the past few years, at present little is known about the harmful effects of TCA and its atmospheric precursors (such as tetrachloroethylene, PER) on wild and forest plant species. Therefore experiments lasting a number of years were carried out on pine trees (Pinus sylvestris L.) and birch trees (Betula pendula Roth) with respect to the chronic uptake of airborne PER via the air/leaf pathway, the aim being to study the fate of PER and its metabolisation into TCA. This work was augmented by outdoor model experiments on pines about 10 years old regarding the uptake of TCA-Na via the soil/root pathway. Chlorophyll a fluorescence measurements on needles and leaf material affected by TCA-Na and PER indicated that the extent to which TCA influences photochemical and biochemical mesophyll processes varies depending on the entry pathway, the particular part of the plant directly affected by TCA, and weather-related factors. It was proven that TCA-Na applied via the soil/root pathway moderately raises the vitality of pine trees depending on the concentration involved, despite high levels of TCA in the needles (up to 1 800μg TCA kg –1 dry weight needles). By contrast, fumigating pine trees and birch trees with PER led to the accumulation of up to 70μg TCA kg –1 dw in the assimilation organs and exacerbated the trees’ sensitivity to stressors. Although physiological activity was initially stimulated, the effect of additional stress in the form of an artificially induced drought caused PER-affected birch trees, in particular, to sometimes undergo sharp losses of vitality of as much as 58% compared to the controls. One may thus expect that, future climate changes accompanied by long periods of drought are likely to exacerbate the ecotoxicological risk in regions with high PER pollution, possibly resulting in the vegetation in the terrestrial ecosystems of the areas concerned being destabilised.

Large crystal local-field effects in the dynamical structure factor of rutileTiO2

We present ab initio time-dependent density-functional calculations and nonresonant inelastic x-ray scattering measurements of the dynamical structure factor of rutile ${\mathrm{TiO}}_{2}$. Our calculations are in good agreement with experiment and prove the presence of large crystal local-field effects below the Ti $M$ edge, which yield a sharp loss peak at 14 eV whose intensity features a remarkable nonmonotonic dependence on the wave vector. These effects, which impact the excitation spectra in the oxide more dramatically than in transition metals, provide a signature of the underlying electronic structure.

Study on the pyrolysis of wood-derived rayon fiber by thermogravimetry–mass spectrometry

The thermal pyrolysis of wood-derived rayon fiber has been studied from ambient temperature up to 800 °C by thermogravimetry–mass spectrometry (TG–MS) analysis in an inert environment. Following an initial plateau region, the wood-derived rayon fiber rapidly decomposes in a narrow temperature range of 300–350 °C. After this sharp weight loss, there is a gradual but constant weight loss up to 800 °C. The values of kinetic parameters have been determined by using two dynamic thermogravimetric curves (TG and DTG). The data show that kinetics of wood-derived rayon fiber is similar to that of other cellulosic materials thermal degradation. Gases and tarry volatile products formed from the pyrolysis of wood-derived rayon fiber are monitored by MS. Water ( m/z 18) is the predominant ion observed, followed by CO ( m/z 28), CO 2 ( m/z 44) and CH 4 ( m/z 16). The MS signals show that the tarry volatiles are composed of varieties of compounds. The formation reactions of primary products from the pyrolysis are discussed in detail in the present paper.

Adaptive economizing and financial feedback in pure competition

A simple model of pure competition among a finite number of cautious, adaptive economizing firms is used to explore industrial behavior when outputs are bounded by financial feedback. Identical agents share identical trajectories that can converge to a competitive equilibrium, but the slightest heterogeneity in initial conditions, degree of caution, or in unit costs drives all from the market except a subset of competitors who share identical costs and output levels. Those remaining can converge to a competitive equilibrium. If demand is inelastic at such a point, however, fluctuations in output, perhaps after a prolonged period of profitable growth can arise with profitable periods followed by sharp losses or even a complete collapse.

Copolymerization of ethylene and non-conjugated diene with metallocene/methylaluminoxane system supported on MCM-41 mesoporous material

Ethylene was copolymerized with the non-conjugated diene 5,7-dimethylocta-1,6-diene by metallocene catalysts, homogenous and supported on MCM-41 mesoporous material activated by methylaluminoxane at room temperature. The employed metallocenes were (BzCp) 2ZrCl 2 ( 1), (C 18H 37Cp) 2ZrCl 2 ( 2), (CH 3) 2Si(Ind) 2ZrCl 2 ( 3) and ϕ 2C(Cp,Flu)ZrCl 2 ( 4). Diene incorporation and thermal characteristic of the polymers were determined by 13C-NMR and DSC. For the homogeneous systems, only the unbridged metallocene ( 1) showed a decrease in the activity as the diene content was increased. The ability for diene incorporation in the polymer chain followed the catalyst order ( 1) < ( 3) < ( 2) < ( 4). Regarding the supported systems, it was observed that all of them showed lower activity than the corresponding homogeneous catalysts. A sharp loss of activity in relation to the homogeneous counterpart was noticed by employing the ansa-metallocenes on MCM-41, especially the complex ( 4) supported catalyst. The effect of the mesoporous material as support on the behavior of the studied metallocene homogeneous systems in ethylene–diene copolymerization was an increase of polymer molecular weight, maintaining the same level of diene incorporation, except for catalyst ( 2), when a decrease of the diene incorporation was observed.