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Zn1-xCexO nanoparticles with x = 0, 0.01, 0.03, 0.05 and 0.07 were synthesised using a chemical co-precipitation method. The effects of Ce3+doping on the properties of zinc oxide (ZnO) nanoparticles were studied. The prepared nanoparticles were characterised by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy (PL), UV-visible spectroscopy and vibrating sample magnetometry. The CeO2secondary phase induced structural and morphological changes. The Zn-O stretching peak shifted slightly due to the inclusion of Ce3+ions into the ZnO matrix. PL spectroscopy revealed minor defects and a direct bandgap of 2.81-3.15 eV. The samples exhibited diamagnetic behaviour with a ferromagnetic contribution at room temperature. The prepared samples were assessed for their antibacterial efficiency against six bacterial strains using the agar well diffusion method.

Mg-doped CuO nanoparticles (Cu1-xMgxO) capped with ethylenediamine tetraacetic acid (EDTA), 0.000 ≤ x≤ 0.020, have been synthesized by the co-precipitation route. The anti-corrosion behavior of 10 ppm of pure and Mg-doped CuO nanoparticles was studied on mild steel in 0.5 M hydrochloric (HCl) and sulfuric (H2SO4) acids, containing 1% of sodium dodecyl sulfate (SDS) as surfactant. Potentiodynamic polarization and electrochemical impedance spectroscopy were employed to study their anti-corrosion behavior. Based on the results provided, the successful corrosion inhibition of mild steel in 0.5 M HCl and H2SO4solutions has been established and confirmed by Raman measurements at 50 min in the presence of pure and Mg-doped CuO nanoparticles. Mg-doped CuO nanoparticles enhanced the corrosion protection of mild steel in 0.5 M HCl and H2SO4solutions. This might be attributed to the adsorption reaction of Mg2+ions that form a protective film on the mild steel surface. This was confirmed by Raman spectra in both media, where the corrosion products formed such as hematite, goethite, maghemite, and green rust were detected and analyzed.

Zn0.97Mn0.03O and Zn0.87Mn0.03Fe0.1O nanoparticles have been synthesized using co-precipitation technique. The obtained nanoparticles were characterized by X-ray diffraction, and transmission electron microscopy. The elemental contents of the prepared nanoparticles were determined using particle-induced X-ray emission. Besides, the oxygen content of these nanoparticles was determined using non-Rutherford backscattering spectroscopy. The electrochemical behaviour of 10 ppm nanoparticles on the corrosion of mild steel in 0.5 M HCl and 0.5 M NaCl solutions containing 1% SDS was studied using potentiodynamic polarization curve measurements and electrochemical impedance spectroscopy techniques. The mechanism of inhibition of the studied nanoparticles was discussed and explained. Iron containing nanoparticles enhanced the corrosion protection of mild steel in 0.5 M HCl due to the ability of Fe2+to deposit onto metal surface. However, in neutral 0.5 M NaCl medium, both nanoparticles have approximately similar efficiency.

The effect of erbium (Er) doping on the structural, magnetic and mechanical properties of Zn1−xErxO, with 0.00 ≤ x ≤ 0.10, samples was studied using X-ray powder diffraction, M–H magnetic hysteresis and digital Vickers microhardness tester, respectively. The samples were prepared by wet chemical co-precipitation method. Vickers microhardness (Hv) measurements were carried out at different applied loads (0.25–10 N) and dwell times (t = 10–60 s) to study the mechanical performance of the samples. Experimental results of Hvwere analyzed using Meyer’s law, and modeled according to Hays–Kendall, elastic/plastic deformation, modified proportional specimen resistance (MPSR) and Indentation Induced Cracking models. It was observed that the MPSR model was the most appropriate model for describing the load independent microhardness data of Er-doped ZnO nanoparticle samples. Indentation creep behavior of Zn1−xErxO samples was studied at room temperature by measuring the variation of Hvwith the dwell times (t = 10–60 s) at fixed applied loads F = 1, 5 and 10 N, respectively. The results showed that Er-doped ZnO nanoparticles samples possessed grain boundary sliding and dislocation climbs at low loads followed by dislocation creep for higher loads within the operative creep mechanism.

Background: The properties of spinel ferrites are known to be dependent on many various factors and mainly on the cations distribution among the tetrahedral and octahedral sites. Therefore, they are sensitive to the presence of doping cations, the type and the amount of these cations. Many researchers have focused on investigating the effect of doping on spinel ferrites nanoparticles with various types of dopants. Among the dopants, transition metal (TM) ions have shown significant effects and changes on the structural, optical, electric and magnetic properties of spinel ferrites nanoparticles. Objectives: The goal of this work is to investigate the effect of the TM ions Mo5+ on the several properties of manganese ferrites nanoparticles. Methods: Mo-doped manganese ferrites nanoparticles with the general formula MnFe2-xMoxO4 (0≤x≤ 0.1) were prepared by co-precipitation technique using two different methods, depending on the molarity of NaOH and the annealing temperatures. The characterization of the prepared samples was conducted by X-ray powder diffraction (XRD), Energy-Dispersive X-ray (EDX), Transmission Electron Microscopy (TEM), ultraviolet-visible (UV-Vis) absorption spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy in order to investigate the effect of Mo-doping on the structure, crystallite size, morphology, energy gap and functional groups of MnFe2O4 nanoparticles. Vibrating sample magnetometer (VSM) was used to study the magnetic hysteresis of the samples. Results: The XRD patterns show the segregation of MnFe2O4 phase into α-Fe2O3 and Mn2O3 for samples prepared at 4 M NaOH and annealing temperature of 873 K. Whereas, samples prepared at 2 M NaOH without annealing process, obtained a single phase of MnFe2O4. The Eg of both samples decreases with the increase in Mo-doping. FTIR confirms the presence of Fe-O bands corresponding to α-Fe2O3 for annealed samples, and the metal-O bands corresponding to octahedral and tetrahedral sites in non-annealed samples. Magnetic measurements show that annealed samples are antiferromagnetic whereas ferromagnetic behavior is observed in non-annealed samples. Dielectric measurements, for both samples, indicate that the dielectric parameters are strongly dependent on both Mo-concentrations and temperatures. Conclusion: In order to get a single phase of MnFe2O4 nanoparticles, thermal treatment at high temperature and high molarity of NaOH are not recommended. Mo-doping has significant influences on the optical, magnetic and dielectric properties and therefore future studies on the Mo-doping with different and new doping percentages are recommended.

Herein, the co-precipitation method is used to synthesize pure and Zn-doped copper oxide (CuO) nanoparticles with low concentrations, 0.5, 0.75, 1, and 1.25 at.% capped by ethylenediaminetetraacetic acid. The influence of Zn doping on the structural, morphological, optical, and magnetic properties is characterized. X-ray powder diffraction patterns confirm the formation of the monoclinic CuO phase without any impurities. In addition, the Zn dopant revealed the formation of mixed morphology welded with some elongated and small agglomerated nanoparticles. Fourier transform infrared spectra affirm the successful formation of the CuO monoclinic structure. The optical properties were examined in ethanol and propanol solvents, which demonstrated a dependence on the excitation, emission, and solvent. Consequently, the crystallite size and energy band gap are both found to decrease for 0.5 at.% Zn dopant and then increase for the highest concentrations. Furthermore, M–H loops reveal the presence of paramagnetic behavior with weak ferromagnetic nature at the low field with Zn doping. Accordingly, the anti-corrosion behavior of the prepared nanoparticles has been studied. They have 83% corrosion inhibition on mild steel in 0.5 M HCl which is confirmed by impedance and polarization studies.

In this study, the influence of adding Yttrium iron garnet (Y3Fe5O12) nanoparticles (NPs) on the microstructure and fluctuation-induced conductivity (FIC) of Cu0.5Tl0.5Ba2Ca2Cu3O10-δ(CuTl-1223) superconductor was studied. Y3Fe5O12NPs were produced by the co-precipitation technique. By solid state route, (Y3Fe5O12)x/Cu0.5Tl0.5Ba2Ca2Cu3O10-δcomposites, with x= 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10 wt. % were prepared. The tetragonal unit cell parameters of (Y3Fe5O12)x/Cu0.5Tl0.5Ba2Ca2Cu3O10-δcomposites were found to be invariable with Y3Fe5O12content. The volume fraction of the host phase was increased with Y3Fe5O12addition till x= 0.04 wt. %. The different vibrational modes of the samples were identified through Fourier transform infrared spectroscopy (FTIR). The transition from normal to the superconducting state, for the prepared composites, was done through d.c resistivity measurements from room temperature down to zero critical temperature (T0). The Aslamazov–Larkin (AL) model was used to examine fluctuation regions in resistivity-temperature curves. At high temperatures, short wave fluctuation was observed. A cross-over between short wave fluctuation and the mean-field region was spotted at lower temperatures. The mean field region for the examined composites was composed of two-dimensional fluctuations along with one-dimensional fluctuation. The coherence length along the c-axis ζc(0), interlayer coupling (J), and anisotropy parameter (γ) were estimated from the Lawrence–Doniach (LD) model as a function of Y3Fe5O12content.

The addition of magnetic Co0.5Zn0.5Fe2O4nanoparticles to the superconducting Cu0.5Tl0.5-1223 phase has been used to investigate the electrical resistivity behavior of the composite above the superconducting transition temperature Tc. This was studied according to the opening of spin gap and fluctuation conductivity. The results indicated that the pseudogap temperature (T*) and superconducting fluctuation temperature (Tscf) change by increasing the addition of Co0.5Zn0.5Fe2O4nanoparticles. It was found that T* is related to hole carrier concentration Pand it also depends on the antiferromagnetic fluctuation affected by magnetic nanoparticles. The excess-conductivity analysis showed four different fluctuation regions started from high temperature up to Tc, and they were denoted by short wave (sw), two-dimensional (2D), three-dimensional (3D), and critical (cr) fluctuations. The crossover temperature between 3D and 2D (T3D–2D) in the mean field region was decreased by increasing the addition of Co0.5Zn0.5Fe2O4nanoparticles, in accordance with the decrease in Tscfwith x. The coherence length at 0 K along c-axis ξc(0), effective layer thickness of the 2D system d, and inter-layer coupling strength Jwere estimated as a function of Co0.5Zn0.5Fe2O4nanoparticle addition. Moreover, the thermodynamics, lower and upper critical magnetic fields, as well as critical current density have been calculated from the Ginzburg number NG. It was found that the low concentration of Co0.5Zn0.5Fe2O4nanoparticles up to x= 0.08 wt% improves the superconducting parameters of Cu0.5Tl0.5-1223 phase. On the contrary, these parameters were deteriorated for (Co0.5Zn0.5Fe2O4)x/Cu0.5Tl0.5-1223 composite with x> 0.08 wt%.

Superconductor samples of type (CoFe2O4)xGdBa2Cu3O7-δ(0≤x≤0.1) were synthesized by the conventional solid-state reaction technique, whereas nanosized CoFe2O4was prepared by co-precipitation method with grain size of about 8.5 nm. The elemental content of the prepared samples was determined using particle induced X-ray emission (PIXE). The temperature dependence of real (χ') and imaginary (χʺ) components of AC magnetic susceptibility (ACMS) at different magnetic field amplitude (3–15 Oe) was investigated. The analysis of the temperature dependence of ACMS was performed using Bean critical state model. The values of the critical current density Jcat T> Tp(Tpis the inter-granular loss peak temperature) were calculated as a function of magnetic field and nanosized CoFe2O4content. It was found that the low nanosized CoFe2O4addition content (x= 0.01) improves the critical current density Jcof Gd-123 superconducting phase. The observed variation of Jcwith temperature indicated that the weak links are changed from superconductor–normal metal–superconductor (SNS) for free sample to superconductor–insulator–superconductor (SIS) type of junctions for samples added with nanosized CoFe2O4of x> 0.01. We also discussed the experimental results in the framework of the critical state model to estimate the effective volume fraction of the grains fgusing Cole–Cole plots.

The effect of the partial substitution of Ca2+by Ho3+ions on the electrical and mechanical properties of the superconducting phase (Bi,Pb)-2223 was studied. Superconducting samples of the type (Bi1.8Pb0.4)Sr2Ca2.1−xHoxCu3.1O10+δwere prepared by solid-state reaction technique under ambient pressure, and characterized by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The superconducting transition temperature Tcand pseudogap temperature T* were estimated from electrical resistivity measurements, while the critical current density Jcwas determined from I–Vcurves. The electrical resistivity data were discussed according to bipolaron model in the absence of thermally excited individual polarons. The sample with x= 0.025 showed the highest phase volume fraction, Tc, and Jc. Room temperature Vickers microhardness measurements were carried out at different applied loads (0.25–5 N) in order to investigate the performance of the mechanical properties of (Bi1.8Pb0.4)Sr2Ca2.1−xHoxCu3.1O10+δphase. It was found that all the samples exhibit normal indentation size effect (ISE). The Vickers microhardness number HVincreased as xincreased from 0 to 0.025. The experimental results were discussed in view of Meyer’s law, Hays–Kendall (HK) approach, elastic/plastic deformation (EPD) model, and proportional specimen resistance (PSR) model. The load independent (true) microhardness of (Bi1.8Pb0.4)Sr2Ca2.1−xHoxCu3.1O10+δsuperconducting samples showed identical behavior to that of the PSR model.

X-ray powder diffraction, scanning electron microscopy (SEM), energy dispersive X-ray, electrical resistivity and AC-magnetic susceptibility measurements have been performed for polycrystalline superconducting samples of type TlBa2Ca2−x Sc x Cu3O9−δ (0.0 ≤ x ≤ 0.6). The powder X-ray diffractograms indicate that the tetragonal structure of Tl-1223 is not affected by Sc-substitution whereas the lattice parameters are changed. The X-ray analysis indicates that the low-contents of scandium (x) enhance the formation of Tl-1223 and reduce the secondary phases. The grain-size determined by SEM decreases as x increases. The electrical resistivity measurements show suppression in the superconducting transition temperature, T c, and an increase in both the residual resistivity and the superconducting transition width as x increases. The suppression in T c is attributed to the hole-filling mechanism. [ABSTRACT FROM AUTHOR]

The thermomechanical analysis (TMA) of Cu0.5Tl0.5Ba2a2−x R x Cu3O10−δ, where R=Pr and La, with 0.0≤x≤0.15, was carried out in temperature range from 450 to 1145 K. The samples were prepared by single-step solid state reaction technique. The prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The superconductivity of the prepared samples was investigated by electrical resistivity measurement. The results showed that low substitution content enhanced the (Cu0.5Tl0.5)-1223 phase formation, while the higher substitution content degraded this phase. The higher superconducting transition temperatures Tc were found to be 114 K and 109 K at x= 0.025 for Pr- and La-substitutions, respectively The average linear thermal expansion coefficient increased as x increased, while the shrinkage temperature decreased as x increased. Those results were emphasized by porosity and Vickers microhardness calculations. Debye temperature θD was calculated from the linear thermal expansion coefficient data and correlated to Tc to estimate the electron-phonon coupling λep. [ABSTRACT FROM AUTHOR]

The major limitation of Bi-system superconductor applications is the intergrain weak links and weak flux pinning capability producing low critical current density of the Bibased phases. In order to enhance these characteristics and other superconducting properties, effective flux pinning centers are introduced into high temperature superconductors. In this work, different weight percentages of ZnO nano oxide were introduced at the final stage of the Bi1.8Pb0.4Sr2Ca2Cu3O10-y superconductor preparation process. Phase characterization was completed by X-ray diffraction (XRD). Exact constitution of the samples was determined using particle induced X-ray emission (PIXE). Granular and microstructure were investigated using scanning electron microscopy (SEM). Electrical resistivity as function of the temperature was carried to evaluate the relative performance of samples, and finally, E-J characteristic curves were obtained at 77K. Using 0.4 ZnO weight percentage, the electrical and granular properties were greatly enhanced, indicating more efficient pinning mechanisms. A critical current density of 949 A/cm2 was obtained which represents more than twice the value obtained for the pure sample (Jc= 445 A/cm2).

Superconducting samples of TlBa2CaCu2?xScxO7??with x= 0.0,0.025,0.05,0.1,0.15 and 0.2 have been prepared via the solid-state reaction technique. The effect of weak magnetic fields up to 4.4 kG on the electrical resistivity of the prepared samples has been studied to investigate the flux motion for this phase. The results reveal a slight shift in the superconducting transition temperature Tcand an increase in the superconducting transition width ?Twith increasing magnetic field. The magnetic field has a small effect on the electrical resistivity in the normal state and in the first stage of transition, whereas the change in the second stage of superconducting transition is very large. The experimental data, in the second stage of superconducting transition, fit well with the thermally activated flux creep model and the activation energy U(B) shows a power law dependence on magnetic field as B??. Also, the transition width is related to the magnetic field according to the relation ?T?Bn. The values of ? and nare strongly dependent on the scandium content. The magnetic field and temperature dependence of the activation energy U(B,T) is found to be U(B,T)~?TB??, where ? = ?+n. The critical current density Jc(0) and the upper critical field Bc2(0) are calculated, from the above measurements, as a function of scandium content. Finally, the electronic thermal conductivity ?e, estimated from the Wiedermann-Franz law, is reported at different applied magnetic fields for the prepared samples.

Bulk superconductor samples of type TlBa2Ca2(Cu3?xCox)O9??with were prepared by a single-step solid-state reaction. The prepared samples were characterized by powder x-ray diffraction and the superconductivity of these samples was investigated by electrical resistivity and ac magnetic susceptibility. The x-ray data indicate that the lattice parameters aand cvary but the structure of Tl-1223 remains tetragonal with cobalt substitution up to x= 0.6. The transition temperature 'TC', deduced from electrical resistivity and ac magnetic susceptibility measurements, is suppressed by substituting Co impurities at Cu sites. The suppression in TChas been discussed using a Cooper pair-breaking mechanism due to the Abrikosov and Grokov model. The effects of external magnetic field on the ac magnetic susceptibility as well as calculations of critical current density as a function of cobalt content and temperature are reported.

Bulk superconductor samples of type TlBa2Ca2(Cu3−xCox)O9−δ with were prepared by a single-step solid-state reaction. The prepared samples were characterized by powder x-ray diffraction and the superconductivity of these samples was investigated by electrical resistivity and ac magnetic susceptibility. The x-ray data indicate that the lattice parameters a and c vary but the structure of Tl-1223 remains tetragonal with cobalt substitution up to x = 0.6. The transition temperature ‘TC ’, deduced from electrical resistivity and ac magnetic susceptibility measurements, is suppressed by substituting Co impurities at Cu sites. The suppression in TC has been discussed using a Cooper pair-breaking mechanism due to the Abrikosov and Grokov model. The effects of external magnetic field on the ac magnetic susceptibility as well as calculations of critical current density as a function of cobalt content and temperature are reported.

In Palestine, there has been an increase in the reported incidence of acute hepatitis A virus (HAV) infection since 1995. Since overt clinical disease occurs only among adults, questions were raised whether or not a shift in the epidemiology of HAV has occurred. This is generally characterized by a decrease in the overall incidence rate and a shifting in the mean age of infection towards adolescence and early adulthood. The need for a vaccination programme is being discussed. To resolve this issue, we examined the prevalence of anti-HAV in a representative sample of 396 school children in the Gaza Strip. The prevalence of anti-HAV was 93·7% (95% CI: 91·3, 96·1%). Stratifying the prevalence by age showed that 87·8% (95% CI: 78·6, 97%) were HAV antibody positive by the age of 6. By the age of 14, almost 98% (95% CI: 92·7, 100%) were HAV antibody positive. This means that the majority of HAV infection is still taking place in early childhood, when it is usually asymptomatic and of little clinical significance. The results refuted the shifting epidemiology theory and we recommend that a vaccination programme against HAV infection is not yet needed. Alternative explanations for the increase in reported cases are discussed.

Processed cheese spreads were produced using Ras cheese as the cheese base with salt mixtures (i) Na-pyrophosphate + Na-polyphosphate, (ii) Na-pyrophosphate + Na-polyphosphate + Na-tripolyphosphate, and (iii) Na-pyrophosphate + Na-polyphosphate + Na-orthphosphate + Na-tripolyphosphate. For comparison, cheese spreads were also made with commercial emulsifying salts JOHA S10, S9 special, and NO. Texture profile analysis showed that the values of chewiness, gumminess, adhesiveness, and hardness were significantly different for various treatments. Also, the texture profile values increased upon storage and were highest in the samples stored at room temperature. The light microscopy photographs indicated different emulsification degree with various emulsifying salt mixtures. These observations were also confirmed with the image analysis and Transmission Electron Microscopy.

Processed cheese spreads were produced using Ras cheese and various emulsifying salt mixtures. Acidified Ras cheese (2 months old) was used as the cheese base and blended with following emulsifying salt mixtures: (i) Na-pyrophosphate + Na-polyphosphate, (ii) Na-pyrophosphate + Na-polyphosphate + Na-tripolyphosphate, and (iii) Na-pyrophosphate + Na-polyphosphate + Na-orthophosphate + Na-tripolyphosphate. The control cheese spreads were also made with commercial emulsifying salts, Joha S10, S9s, and NO. Water activity, oil index, meltability, flow behavior, color parameters and sensory evaluations for the resultant processed cheese were studied. Cheeses showed slight differences in water activity while the differences were significant in oil index and meltability values. Shear stress of the processed cheese samples measured at 60°C was different from that of the control. It was dependent upon the individual salts in emulsifying mixture. Spreadable Ras cheese was shinier in treatment (iii) and exhibited darker color in samples stored at room temperature (20°C). Sensory evaluation showed that all cheeses were acceptable but the mixtures (i) 70:30, (ii) 60:30:10, and (iii) 50:20:20:10 produced the most acceptable processed cheese.

Little attention has been given to the content uniformity of dispersed solid drugs in suppositories. Problems like sedimentation and/or incomplete dispersion of drug agglomerates may result in poor content uniformity, particularly when drug is formulated in minute amounts. Addition of lactose, as an inert carrier to a drug, at an optimal drug-carrier ratio has shown to improve content uniformity of suppositories. Time of mixing is another parameter which has also been optimized. In addition to the coefficient of variation a sedimentation Index 'SI' has been proposed as in-process control parameter to evaluate the content uniformity of suppositories. Value of unity for 'SI' indicates absence of sedimentation; a problem which is mainly encountered with mixing of solids in liquids or melted suppository bases

The determination of the rate and pH dependency of chlorination of amino acids by chloramine-T (CAT) using the model compounds β-alanine, L-alanine, and L-alanine ethyl ester was investigated. The reactions were studied under pseudo-first-order conditions where the amino acid concentration was in large excess over CAT. The rates of the reactions were determined spectrophotometrically by following the disappearance of CAT. The overall reaction was found to obey second-order kinetics. The effect of pH was studied over the range 6.1 to 12.0. The reaction rate was found to be independent of pH in the range 6.1 to 8.5, and to decrease with increasing pH above 8.5. The pH dependency was rationalized by assuming that un-ionized CAT reacts with the un-ionized amino group of the amino acid. The value of the resulting second-order rate constant (1.9 × 107M−1min−1) was of the same order of magnitude as rate constants reported for similar N-chlorination reactions. A cyclic transition state involving a water molecule is proposed.

Abstract: Irritable bowel syndrome is the most frequently diagnosed disorder in gastroenterology. It has been demonstrated with specialized motility studies that these patients compared to healthy subjects show changes in rectoanal electrical and mechanical activity and in rectoanal sensitivity. However, until now no report has been published on morphological alterations in the rectum or the internal anal sphincter. Twenty-five consecutive patients with irritable bowel syndrome (mean age 32, range 17–47 years; 24 females) were evaluated prospectively by transrectal ultrasonography, rectal sensitivity studies, and recordings of both electrical and mechanical activity of the distal rectum and internal anal sphincter during a 2-h interdigestive period. Ten healthy volunteers (mean age 34.5, range 19–50 years) served as a control group. Paired and non-paired Student's two-tailed t test and linear regression analysis were used. It was shown that muscle thickness of the rectum during rest (4.7±0.1 mm) was correlated neither with its rectal spike amplitude (0.73±0.1 mV) nor with rectal spike frequency (17.06±3.6 spike/2 h). In addition, the diameter of the internal anal sphincter (1.2±0.1 mm) was correlated neither with its resting pressure, nor with frequency (17.1±3.2/2 h), duration (14.9±1.5 s), or amplitude (14.1 ±1.9 mmHg), of inhibition of the spontaneous rectoanal inhibitory reflex. No correlation was found between ultrasonographic parameters and rectal distension variables (r=0.03). This study demonstrates for the first time morphological anorectal changes in patients with irritable bowel syndrome compared to healthy subjects, in addition to showing that morphological changes are independent of physiological ones. Therefore both transrectal ultrasonography to determine anorectal morphology and electromanometry to assess anorectal function are important measures in the evaluation of patients with irritable bowel syndrome.

Abstract.: Background: In patients with IBS, many symptoms have their origin in the recto-anal segment, with motility changes in the rectum and in the internal anal sphincter, and alterations in rectal sensitivity. However, up to now, it is not known if these clinical and physiological changes are equated with morphological changes in the recto-anal segment. Methods: Sixteen consecutive patients with IBS (mean age 22, range 18–33 years; 13 females) and 10 healthy volunteers (mean age 34.5, range 19–50 yr.; 6 males) were evaluated prospectively with defaecography. Results: 1) Anorectal angle: No significant differences were observed in the anorectal angle during rest (91.6 ± 3.5° vs 92.6 ± 2.5°) and during defaecation (92 ± 5.5° vs 98.7 ± 2.6°) between patients with IBS and healthy volunteers. However, patients wih IBS were unable to widen the angle during defaecation, remaining the same at rest (91.6 ± 3.5°) as during defaecation (92 ± 5.5°). IBS patients with constipation (n = 2) compared to those with normal frequency defaecation (n = 13) showed no significant differences at rest (95 ± 6 vs 89.8 ± 4.1°) and during defaecation (100 ± 8 vs 88.9 ± 6.4°). Healthy volunteers widened the angle by more than 5° during defaecation. 2) Perineometry: although not significant, patients with IBS had less perineal descent during the simulated defaecation (1.98 ± 0.37 cm) than healthy subjects (2.1 ± 0.3 cm). Nevertheless, during squeeze there was significantly less mobility or perineal descent in patients with IBS than in control subjects (0.21 ± 0.17 vs 0.95 ± 0.21 cm; P = 0.01). Conclusions: The findings of this study suggest that patients with IBS as a whole, whether constipation predominant or not, showed changes in pelvic-floor mobility.

OMethyl oquinone monoxime 1 reacts thermally with compounds 2ador 6a,bor 7a,bto give mainly the corresponding 2substituted phenanthroxazoles 3acand 8. The reaction of 1 with aromatic methylene compounds lOacaffords the ketones 13acin moderate to high yields. Similar products are also obtained from the reaction of monoximes 15a,bwith some of the above reactants. The unexpected products 5and 20are obtained from the reaction of 1with 2methylimidazole 2d and with phenyloxirane 19 respectively, while the 4H1,4oxazine derivative 23is obtained from the reaction of 1with indene 21.

Standardization and calibration of a new colorimetric assay for detection of reverse transcriptase (RT) was carried out for optimal detection of RT activity-blocking antibody (RTb-Ab) in serum. A total of 99 of 100 Swedish and 54 of 54 African human immunodeficiency virus type 1 (HIV-1) antibody-positive individuals had RTb-Ab. The one RTb-Ab-negative HIV-1 serum sample from a Swedish individual was obtained early during seroconversion. Five of 615 HIV-1-negative sera from tumor patients, pregnant women, patients undergoing routine viral diagnostics, and blood donors gave false-positive results. In addition, 3 of 126 HIV-1-negative African serum samples and 2 of 91 serum samples selected because of false reactivity in other commercially available HIV antibody assays were positive for RTb-Ab. RT activity and RTb-Ab were measured in sera from newly HIV-1-infected individuals during seroconversion. Peak RT activity was usually detected between days 8 and 13 after the onset of symptoms of primary infection. In addition, HIV-1 RTb-Ab was detected in the same recently infected individuals in most cases within 1 month and in some cases as early as 10 to 12 days after the onset of symptoms. A cross-reactivity study involving HIV-1 and HIV-2 RTb-Abs and their homologous RT showed HIV-1 RTb-Ab to be highly type specific. None of 10 serum samples from HIV-1-infected individuals showed cross-reacting RTb-Ab toward HIV-2 RT, whereas 4 of 10 serum samples from HIV-2-infected patients showed cross-reactivity toward HIV-1 RT; however, the cross-reactivity toward HIV-1 RT was 3,000 times lower than that toward its homologous RT. Future uses for the assay with reference to the recent World Health Organization proposal for other methods instead of Western blotting (immunoblotting) for confirming HIV-1 infection and for methods for the diagnosis of infection as follow-up in vaccine trials are also discussed.

The alpha-adrenergic receptor mechanism in rabbit aorta was examined for the involvement of alpha-1 or alpha-2 receptor subtypes. Agonists (phenylephrine, norepinephrine and clonidine) and antagonists (prazosin and yohimbine) with known receptor subtype selectivity were used to define the contribution of alpha-1 or alpha-2 receptors to receptor-initiated cellular Ca++ influx, intracellular release of Ca++ and overall contraction. The receptor content of isolated membranes was also measured in [3H]prazosin and [3H]yohimbine radioligand binding studies. Contraction-derived KB values for prazosin (3 nM) or yohimbine (1 microM) were similar for all three agonists, indicating that each acted on the same alpha-1 receptor. Prazosin (10(-7) M) was effective in causing inhibition of cellular Ca++ influx initiated by agonists whereas yohimbine (10(-6) M) had no effect. Prazosin but not yohimbine caused a partial reduction in phenylephrine or norepinephrine-induced stimulation of 45Ca efflux rate whereas the smaller clonidine-induced stimulation was totally inhibited by prazosin and partially inhibited by yohimbine. Alpha-1 specific binding of [3H]prazosin was observed with a KD of 3.5 nM and maximum binding site (Bmax) of 73 fmol/mg of protein. Although no alpha-2 specific binding of [3H]yohimbine was observed, binding to a low-affinity/high-capacity class of sites was found. The results indicate the sole presence and contribution of alpha-1 receptors to Ca++ flux and contractile events in the rabbit aorta.

The kinetics of decomposition of the following conformationally restricted N-chloro-α-amino acids were studied: 1-amino-1- cyclopentanecarboxylic acid (2), 1-amino-1-cyclohexanecarboxylic acid (4), 2-amino-2-norbornanecarboxylic acid (6), and 2-amino-2- benzonorbornanecarboxylic acid (8). The first-order rate constants obtained were 0.520, 5.197, 0.198, and 0.078, respectively, which correlated with the ring strain in the structurally related cyclic ketones cyclopentanone, cyclohexanone, norborane-2-one, and benzonorbornane-2-one. The data are supportive of a concerted mechanism for the decomposition reaction involving an imine-like transition state.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.