nH Values Research Articles

Disinfection by methylthionine chloride and chitosan in combination with Photo radiation therapy on caries affected dentin nano hardness, adhesive integrity, and bond failure.

The aim of the study was to assess the disinfection efficacy, bond integrity, and nano hardness of caries-affected dentin (CAD) surface bonded to resin cement when disinfected with chlorhexidine (CHX), Methylene blue activated by Photodynamic therapy (MB-PDT), chitosan, silver diamine fluoride (SDF), chitosan activated by PDT, and SDF-diode laser against S. mutans. A total of 60 human mandibular molars were extracted non-traumatically and gathered using ICDAS criteria. The dentin surface was prepared, leaving CAD to receive a disinfection procedure. After inoculation with S. mutans, the CAD samples were divided into six groups and disinfected with various disinfectants (n = 10) CHX, MB-PDT, chitosan, chitosan-PDT, SDF, and SDF+ diode laser. Survival rates of S. mutans were analyzed following the restoration of samples with resin cement via the etch and rinse method to assess SBS. Also, nano hardness was analyzed. Statistical analysis was performed by using the ANOVA and the Tukey multiple test (p<0.05). The Kruskal-Wallis test was used to evaluate the change in survival rate. Related to the survival rates, the SDF+ diode laser displayed the highest reduction in S. mutans levels and chitosan presented the lowest level of disinfection. The intergroup comparison revealed that CHX and chitosan-PDT displayed comparable outcomes of S. mutans survival rate to that of SDF+ diode laser (p>0.05). Likewise, MB-PDT and SDF displayed a comparable survival rate of S. mutans to Chitosan disinfection (p>0.05). Considering SBS and nano hardness, the highest SBS and NH were exhibited by the SDF+ diode laser, and the lowest SBS and NH values were exhibited by MB-PDT. The intragroup comparison revealed that CAD specimens disinfected with Chitosan-PDT showed comparable SBS and NH values to the SDF+ diode laser (p>0.05). CHX, chitosan, and SDF exhibited bond values and NH comparable to MB-PDT (p<0.05). Synergistic use of Silver diamine fluoride with diode laser and chitosan activated by PDT can be used as an alternative to CHX for controlling S. mutans growth, promoting enhanced bond efficacy and nano hardness for bonding resin cement to the caries-affected dentin.

A machine learning algorithm for reliably predicting active galactic nucleus absorbing column densities

We present a new method for predicting the line-of-sight column density (NH) values of active galactic nuclei (AGN) based on mid-infrared (MIR), soft X-ray, and hard X-ray data. We developed a multiple linear regression machine learning algorithm trained with WISE colors, Swift-BAT count rates, soft X-ray hardness ratios, and an MIR–soft X-ray flux ratio. Our algorithm was trained off 451 AGN from the Swift-BAT sample with known NH and has the ability to accurately predict NH values for AGN of all levels of obscuration, as evidenced by its Spearman correlation coefficient value of 0.86 and its 75% classification accuracy. This is significant as few other methods can be reliably applied to AGN with Log(NH &lt; 22.5). It was determined that the two soft X-ray hardness ratios and the MIR–soft X-ray flux ratio were the largest contributors toward accurate NH determinations. We applied the algorithm to 487 AGN from the BAT 150 Month catalog with no previously measured NH values. This algorithm will continue to contribute significantly to finding Compton-thick (CT) AGN (NH ≥ 1024 cm−2), thus enabling us to determine the true intrinsic fraction of CT-AGN in the local Universe and their contribution to the cosmic X-ray background.

Abnormal network homogeneity of default-mode network and its relationships with clinical symptoms in antipsychotic-naïve first-diagnosis schizophrenia.

Schizophrenia is a severe mental disorder affecting around 0.5–1% of the global population. A few studies have shown the functional disconnection in the default-mode network (DMN) of schizophrenia patients. However, the findings remain discrepant. In the current study, we compared the intrinsic network organization of DMN of 57 first-diagnosis drug-naïve schizophrenia patients with 50 healthy controls (HCs) using a homogeneity network (NH) and explored the relationships of DMN with clinical characteristics of schizophrenia patients. Receiver operating characteristic (ROC) curves analysis and support vector machine (SVM) analysis were applied to calculate the accuracy of distinguishing schizophrenia patients from HCs. Our results showed that the NH values of patients were significantly higher in the left superior medial frontal gyrus (SMFG) and right cerebellum Crus I/Crus II and significantly lower in the right inferior temporal gyrus (ITG) and bilateral posterior cingulate cortex (PCC) compared to those of HCs. Additionally, negative correlations were shown between aberrant NH values in the right cerebellum Crus I/Crus II and general psychopathology scores, between NH values in the left SMFG and negative symptom scores, and between the NH values in the right ITG and speed of processing. Also, patients’ age and the NH values in the right cerebellum Crus I/Crus II and the right ITG were the predictors of performance in the social cognition test. ROC curves analysis and SVM analysis showed that a combination of NH values in the left SMFG, right ITG, and right cerebellum Crus I/Crus II could distinguish schizophrenia patients from HCs with high accuracy. The results emphasized the vital role of DMN in the neuropathological mechanisms underlying schizophrenia.

Development of a Quasi-Quantitative Structure-Activity Relationship Model for Prediction of the Immobilization Response of Daphnia magna Exposed to Metal-Based Nanomaterials.

The conventional Hill equation model is suitable to fit dose–response data obtained from performing (eco)toxicity assays. Models based on quasi–quantitative structure–activity relationships (QSARs) to estimate the Hill coefficient (nH) were developed with the aim of predicting the response of the invertebrate species Daphnia magna to exposure to metal‐based nanomaterials. Descriptors representing the pristine properties of nanoparticles and media conditions were coded to a quasi–simplified molecular input line entry system and correlated to experimentally derived values of nH. Monte Carlo optimization was used to model the set of nH values, and the model was trained on the basis of reported dose–response relationships of 60 data sets (n = 367 individual response observations) of 11 metal‐based nanomaterials as obtained from 20 literature reports. The model simulates the training data well, with only 2.3% deviation between experimental and modeled response data. The technique was employed to predict the dose–response relationships of 15 additional data sets (n = 72 individual observations) not included in model development of seven metal‐based nanomaterials from 10 literature reports, with an average error of 3.5%. Combining the model output with either the median effective concentration value or any other known effect level as obtained from experimental data allows the prediction of full dose–response curves of D. magna immobilization. This model is an accurate screening tool that allows the determination of the shape and slope of dose–response curves, thereby greatly reducing experimental effort in case of novel advanced metal‐based nanomaterials or the prediction of responses in altered exposure media. This screening model is compliant with the 3Rs (replacement, reduction, and refinement) principle, which is embraced by the scientific and regulatory communities dealing with nano‐safety. Environ Toxicol Chem 2022;41:1439–1450. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Substitutions at a rheostat position in human aldolase A cause a shift in the conformational population.

Some protein positions play special roles in determining the magnitude of protein function: at such "rheostat" positions, varied amino acid substitutions give rise to a continuum of functional outcomes, from wild type (or enhanced), to intermediate, to loss of function. This observed range raises interesting questions about the biophysical bases by which changes at single positions have such varied outcomes. Here, we assessed variants at position 98 in human aldolase A ("I98X"). Despite being ~17 Å from the active site and far from subunit interfaces, substitutions at position 98 have rheostatic contributions to the apparent cooperativity (nH ) associated with fructose-1,6-bisphosphate substrate binding and moderately affected binding affinity. Next, we crystallized representative I98X variants to assess structural consequences. Residues smaller than the native isoleucine (cysteine and serine) were readily accommodated, and the larger phenylalanine caused only a slight separation of the two parallel helixes. However, the diffraction quality was reduced for I98F, and further reduced for I98Y. Intriguingly, the resolutions of the I98X structures correlated with their nH values. We propose that substitution effects on both nH and crystal lattice disruption arise from changes in the population of aldolase A conformations in solution. In combination with results computed for rheostat positions in other proteins, the results from this study suggest that rheostat positions accommodate a wide range of side chains and that structural consequences manifest as shifted ensemble populations and/or dynamics changes.

An electronic phase diagram of hole-doped BiCuSeO crystals determined by transport characterization under various growth conditions

Temperature-hole-concentration dependent electronic phase-diagram of BiCuSeO.

Hydration/Dehydration Behavior of Hydroxyethyl Cellulose Ether in Aqueous Solution.

Hydroxyethyl cellulose (HeC) maintains high water solubility over a wide temperature range even in a high temperature region where other nonionic chemically modified cellulose ethers, such as methyl cellulose (MC) and hydroxypropylmethyl cellulose (HpMC), demonstrate cloud points. In order to clarify the reason for the high solubility of HeC, the temperature dependence of the hydration number per glucopyranose unit, nH, for the HeC samples was examined by using extremely high frequency dielectric spectrum measuring techniques up to 50 GHz over a temperature range from 10 to 70 °C. HeC samples with a molar substitution number (MS) per glucopyranose unit by hydroxyethyl groups ranging from 1.3 to 3.6 were examined in this study. All HeC samples dissolve into water over the examined temperature range and did not show their cloud points. The value of nH for the HeC sample possessing the MS of 1.3 was 14 at 20 °C and decreased gently with increasing temperature and declined to 10 at 70 °C. The nH values of the HeC samples are substantially larger than the minimum critical nH value of ca. 5 necessary to be dissolved into water for cellulose ethers such as MC and HpMC, even in a high temperature range. Then, the HeC molecules possess water solubility over the wide temperature range. The temperature dependence of nH for the HeC samples and triethyleneglycol, which is a model compound for substitution groups of HeC, is gentle and they are similar to each other. This observation strongly suggests that the hydration/dehydration behavior of the HeC samples was essentially controlled by that of their substitution groups.

Physiological Role of Glutamate Dehydrogenase in Cancer Cells.

increased growth rates and final densities of several human metastatic cancer cells. To assess whether glutamate dehydrogenase (GDH) in cancer cells may catalyze the reverse reaction of fixation, its covalent regulation and kinetic parameters were determined under near-physiological conditions. Increased total protein and phosphorylation were attained in -supplemented metastatic cells, but total cell GDH activity was unchanged. Higher Vmax values for the GDH reverse reaction vs. forward reaction in both isolated hepatoma (HepM) and liver mitochondria [rat liver mitochondria (RLM)] favored an -fixing role. GDH sigmoidal kinetics with , ADP, and leucine fitted to Hill equation showed nH values of 2 to 3. However, the K0.5 values for were over 20 mM, questioning the physiological relevance of the GDH reverse reaction, because intracellular in tumors is 1 to 5 mM. In contrast, data fitting to the Monod–Wyman–Changeux (MWC) model revealed lower Km values for , of 6 to 12 mM. In silico analysis made with MWC equation, and using physiological concentrations of substrates and modulators, predicted GDH N-fixing activity in cancer cells. Therefore, together with its thermodynamic feasibility, GDH may reach rates for its reverse, -fixing reaction that are compatible with an anabolic role for supporting growth of cancer cells.

Broad-band X-ray analysis of local mid-infrared-selected Compton-thick AGN candidates

The estimate of the number and space density of obscured AGN over cosmic time still represents an open issue. While the obscured AGN population is a key ingredient of the X-ray background synthesis models and is needed to reproduce its shape, a complete census of obscured AGN is still missing. Here we test the selection of obscured sources among the local 12-micron sample of Seyfert galaxies. Our selection is based on a difference up to three orders of magnitude in the ratio between the AGN bolometric luminosity, derived from the spectral energy distribution (SED) decomposition, and the same quantity obtained by the published XMM-Newton 2-10 keV luminosity. The selected sources are UGC05101, NGC1194 and NGC3079 for which the available X-ray wide bandpass, from Chandra and XMM-Newton plus NuSTAR data, extending to energies up to ~30-45 keV, allows us an accurate determination of the column density, and hence of the true intrinsic power. The newly derived NH values clearly indicate heavy obscuration (about 1.2, 2.1 and 2.4 x10^{24} cm-2 for UGC05101, NGC1194 and NGC3079, respectively) and are consistent with the prominent silicate absorption feature observed in the Spitzer-IRS spectra of these sources (at 9.7 micron rest frame). We finally checked that the resulting X-ray luminosities in the 2-10 keV band are in good agreement with those derived from the mid-IR band through empirical L_MIR-L_X relations.

Molecular motions, structure and hydration behaviour of glucose oligomers in aqueous solution.

The degree of polymerization and temperature dependencies of the molecular motions, configuration and hydration behaviour of glucose oligomers (Gn, n = 2 to 7, degree of polymerization) in aqueous solutions were investigated using extremely high-frequency dielectric spectrum measuring techniques up to 50 GHz. The obtained dielectric spectra for the aqueous Gn solutions were well decomposed into four Debye-type relaxation modes. The fastest relaxation mode j = 1 was assigned to the rotational process of free water molecules in the sample solution. The second fastest mode j = 2 was attributed to the exchange process of hydrated water molecules with free water molecules, and the third mode j = 3 was recognized as the rotational process of hydroxy groups attached to each repeating glucopyranoside (Glu) unit after their lifetimes of intramolecular hydrogen bonding. The slowest mode j = 4 at a relaxation time depending on n was assigned to the overall rotation of the Gn molecules possessing configurations similar to that of small fragments of single helical V-type crystalline structures at low temperatures. The presence of the dielectric mode j = 4 revealed that the Glu units possessed electric dipole moments carrying a component parallel to the Gn backbone aligned with the C1 → C4 direction. The number of hydrated water molecules per Glu unit (hydration number, nH) was determined for Gns in aqueous solutions in the temperature range from 10 °C to 70 °C via the relaxation strength of mode j = 1. The Gn oligomers were highly soluble in water within the temperature range examined, possessing nH values slightly dependent on n and demonstrated clear dehydration behaviour at approximately 30 °C with increasing temperature. These temperature dependencies of nH were substantially weaker than those of a model Glu unit compound, methyl α-d-glucopyranoside (G1). Then, the polymerization of glucose oligomers effectively depresses the dehydration behaviour of G1.

Origin of the low-temperature plasma in the Galactic center X-ray emission

Abstract The Galactic Center X-ray emission (GCXE) is composed of high-temperature (∼7 keV) and low-temperature (∼1 keV) plasmas (HTP and LTP, respectively). The global structure of the HTP is roughly uniform over the Galactic Center (GC) region, and the origin of the HTP has been extensively studied. On the other hand, the LTP is more clumpy, and its origin has not been studied in detail. In the S xv Heα line map, a pair of horn-like soft diffuse sources are seen at symmetric positions with respect to Sagittarius A⋆. The X-ray spectra of the pair are well represented by an absorbed thin thermal plasma model of temperature and NH of 0.6–0.7 keV and 4 × 1022 cm−2, respectively. The NH values indicate that the pair are located near the GC. Then the dynamical time scales of the pair are ∼105 yr. The Si and S abundances and the surface brightnesses in the S xv Heα line band are 0.7–1.2 and 0.6–1.3 solar, and (2.0–2.4) × 10−15 erg s−1 cm−2 arcmin−2, respectively. The temperature, abundances, and surface brightness are similar to those of the LTP in the GCXE, while the abundances are far larger than those of known point sources, typically coronal active stars and RS CVn-type active binaries. Based on these results, the possible origin of the LTP is discussed.

Hydration of urea and alkylated urea derivatives.

Compressibility data and broadband dielectric spectra of aqueous solutions of urea and some of its alkylated derivatives have been evaluated to yield their numbers Nh of hydration water molecules per molecule of solute. Nh values in a broad range of solute concentrations are discussed and are compared to hydration numbers of other relevant molecules and organic ions. Consistent with previous results, it is found that urea differs from other solutes in its unusually small hydration number, corresponding to just one third of the estimated number of nearest neighbor molecules. This remarkable hydration behavior is explained by the large density φH of hydrogen bonding abilities offered by the urea molecule. In terms of currently discussed models of reorientational motions and allied dynamics in water and related associating liquids, the large density φH causes a relaxation time close to that of undisturbed water with most parts of water encircling the solute. Therefore only a small part of disturbed ("hydration") water is left around each urea molecule. Adding alkyl groups to the basic molecule leads to Nh values which, within the series of n-alkylurea derivatives, progressively increase with the number of methyl groups per solute. With n-butylurea, Nh from dielectric spectra, in conformity with many other organic solutes, slightly exceeds the number of nearest neighbors. Compared to such Nh values, hydration numbers from compressibility data are substantially smaller, disclosing incorrect assumptions in the formula commonly used to interpret the experimental compressibilities. Similar to other series of organic solutes, effects of isomerization have been found with alkylated urea derivatives, indicating that factors other than the predominating density φH of hydrogen bond abilities contribute also to the hydration properties.

Modelling the effects of quinidine, disopyramide, and E-4031 on short QT syndrome variant 3 in the human ventricles

Objective: Short QT syndrome (SQTS) is an inherited cardiac channelopathy, but at present little information is available on its pharmacological treatment. SQT3 variant (linked to the inward rectifier potassium current IK1) of SQTS, results from a gain-of-function mutation (Kir2.1 D172N) in the KCNJ2-encoded channels, which is associated with ventricular fibrillation (VF). Using biophysically-detailed human ventricular computer models, this study investigated the potential effects of quinidine, disopyramide, and E-4031 on SQT3. Approach: The ten Tusscher et al model of human ventricular myocyte action potential (AP) was modified to recapitulate the changes in IK1 due to heterozygous and homozygous forms of the D172N mutation. Wild-type (WT) and mutant WT-D172N and D172N formulations were incorporated into one-dimensional (1D) and 2D tissue models with transmural heterogeneities. Effects of drugs on channel-blocking activity were modelled using half-maximal inhibitory concentration (IC50) and Hill coefficient (nH) values. Effects of drugs on AP duration (APD), effective refractory period (ERP) and QT interval of pseudo-ECGs were quantified, and both temporal and spatial vulnerability to re-entry was measured. Re-entry was simulated in the 2D ventricular tissue. Main results: At the single cell level, the drugs quinidine, disopyramide, and E-4031 prolonged APD at 90% repolarization (APD90), and decreased maximal transmural voltage heterogeneity (δV); this caused the decreased transmural dispersion of APD90. Quinidine prolonged the QT interval and decreased the T-wave amplitude. Furthermore, quinidine increased ERP and reduced temporal vulnerability and increased spatial vulnerability, resulting in a reduced susceptibility to arrhythmogenesis in SQT3. In the 2D tissue, quinidine was effective in terminating and preventing re-entry associated with the heterozygous D172N condition. Quinidine exhibited significantly better therapeutic effects on SQT3 than disopyramide and E-4031. Significance: This study substantiates a causal link between quinidine and QT interval prolongation in SQT3 Kir2.1 mutations and highlights possible pharmacological agent quinidine for treating SQT3 patients.

Modeling the effects of amiodarone on short QT syndrome variant 2 in the human ventricles.

The short QT syndrome (SQTS) is a new genetic disorder associated with atrial and ventricular arrhythmias and sudden death. The SQT2, SQTS variant, results from a gain-of-function mutation (V307L) in the KCNQ1-encoded potassium channel. Although pro-arrhythmogenic effects of SQTS have been characterized, less is known about the pharmacology of SQTS. Therefore, this study aims to assess the effects of amiodarone on SQT2. The ten Tusscher et al. model of the human ventricular action potential (AP) was modified to incorporate changes to IKs based on experimental data. Cell models were incorporated into heterogeneous one-dimensional (1D) tissue to compute the pseudo-ECG and the corresponding QT interval. The blocking effects of amiodarone on IKs, INa, INaK, ICaL, INaCa, and IKr were modeled using nH (Hill coefficient) and IC50 values from the literature. At the cellular level, amiodarone both at low and high doses prolonged the SQT2 AP duration (APD); at the tissue level, amiodarone at a high dose caused QT prolongation to the physiological range, but failed at a low dose. Amiodarone at a high dose produced better therapeutic effects on SQT2 than at a low dose. This study provides new evidence that amiodarone at a high dose may be a potential pharmacological treatment for SQT2.

In silico assessment of the effects of quinidine, disopyramide and E-4031 on short QT syndrome variant 1 in the human ventricles.

AimsShort QT syndrome (SQTS) is an inherited disorder associated with abnormally abbreviated QT intervals and an increased incidence of atrial and ventricular arrhythmias. SQT1 variant (linked to the rapid delayed rectifier potassium channel current, IKr) of SQTS, results from an inactivation-attenuated, gain-of-function mutation (N588K) in the KCNH2-encoded potassium channels. Pro-arrhythmogenic effects of SQT1 have been well characterized, but less is known about the possible pharmacological antiarrhythmic treatment of SQT1. Therefore, this study aimed to assess the potential effects of E-4031, disopyramide and quinidine on SQT1 using a mathematical model of human ventricular electrophysiology.MethodsThe ten Tusscher et al. biophysically detailed model of the human ventricular action potential (AP) was modified to incorporate IKr Markov chain (MC) formulations based on experimental data of the kinetics of the N588K mutation of the KCNH2-encoded subunit of the IKr channels. The modified ventricular cell model was then integrated into one-dimensional (1D) strand, 2D regular and realistic tissues with transmural heterogeneities. The channel-blocking effect of the drugs on ion currents in healthy and SQT1 cells was modeled using half-maximal inhibitory concentration (IC50) and Hill coefficient (nH) values from literatures. Effects of drugs on cell AP duration (APD), effective refractory period (ERP) and pseudo-ECG traces were calculated. Effects of drugs on the ventricular temporal and spatial vulnerability to re-entrant excitation waves were measured. Re-entry was simulated in both 2D regular and realistic ventricular tissue.ResultsAt the single cell level, the drugs E-4031 and disopyramide had hardly noticeable effects on the ventricular cell APD at 90% repolarization (APD90), whereas quinidine caused a significant prolongation of APD90. Quinidine prolonged and decreased the maximal transmural AP heterogeneity (δV); this led to the decreased transmural heterogeneity of APD across the 1D strand. Quinidine caused QT prolongation and a decrease in the T-wave amplitude, and increased ERP and decreased temporal susceptibility of the tissue to the initiation of re-entry and increased the minimum substrate size necessary to prevent re-entry in the 2D regular model, and further terminated re-entrant waves in the 2D realistic model. Quinidine exhibited significantly better therapeutic effects on SQT1 than E-4031 and disopyramide.ConclusionsThe simulated pharmacological actions of quinidine exhibited antiarrhythmic effects on SQT1. This study substantiates a causal link between quinidine and QT interval prolongation in SQT1 and suggests that quinidine may be a potential pharmacological agent for treating SQT1 patients.

Kinetic behavior in self-assembly process of associative polymer solutions

ABSTRACTUsing associative polymers with different micro-block length (NH), their kinetic behaviors in the self-assembly process have been discussed with steady flow, step shear rate and dynamic light scattering (DLS) experiments. The results showed that the NH is the most important parameter to affect rheology of associative polymers, and the equilibrium time and viscosity recovery are an obvious difference from seconds to hours after violent pre-shearing. With DLS data, the hydrophobic micro-zone size is always a polydispersion distribution, and gradually concentrated three scales of size, the associative polymers with higher NH values have a longer time to reach equilibrium state. The kinetic behavior of associative polymers has a greater potential to apply in enhanced oil recovery (EOR) field, we conclude that the polymers with medium associative strength have a smaller shear thinning index and higher viscosity recovery, and may satisfy the polymer flooding requirements of displacement efficiency and injectivity.

Suzaku observations of two diffuse hard X-ray source regions, G22.0+0.0 and G23.5+0.1

Abstract G22.0+0.0 and G23.5+0.1 are diffuse hard X-ray sources discovered in the ASCA Galactic Plane Survey. We present Suzaku results of spectral analysis for these sources. G22.0+0.0 is confirmed to be a largely extended emission. Its spectra were represented by a highly absorbed power-law model with a photon index of 1.7 ± 0.3 and a moderately absorbed thermal emission with a temperature of 0.34$^{+0.11}_{-0.08}\:$keV. The difference in the NH values between the two components suggests that the thermal component is unrelated to the power-law component and is a foreground emission located in the same line of sight. G23.5+0.1 is an extended source with a size of ∼3${^{\prime}_{.}}$5. Its spectra were fitted with an absorbed power-law model with a photon index of 2.4$^{+0.5}_{-0.4}$. The spatial and spectral properties show that both sources are candidates for old pulsar wind nebulae (PWNe). In addition to the extended sources, we analyzed spectra of three point sources found in the observed fields. Based on the spectral features, we discuss the origin of the sources.

INTERSTELLAR DUST PROPERTIES FROM A SURVEY OF X-RAY HALOS

Interstellar dust grains produce X-ray halos around bright sources due to small-angle X-ray scattering. Numerous studies have examined these halos, but no systematic study has yet tested the available halo data against the large number of well-defined dust models in circulation. We have therefore obtained the largest sample to date of X-ray dust halos from XMM-Newton and Chandra, and fitted them with 14 commonly used dust grain models, including comparisons with the optical extinction, AV, where available in the literature. Our main conclusions are summarized as follows. (1) Comparing AV with NH values measured via X-ray spectral fits, we find a ratio of AV/NH (1021 cm?2) = 0.48 ? 0.06, in agreement with previous work. (2) Out of 35 halos, 27 could be fit by one or more grain models, with the most successful models having maximum grain radius ?m and fewer large grains than the less successful models. This suggests that the diffuse ISM does not contain a signicant presence of grains with ?m. (3) Most halos were best fit assuming a single dust cloud dominated the scattering, rather than smoothly distributed dust along the sightline. (4) Eight sources could not be fit with the models considered here, most of which were along distant ( kpc) sight lines through the Galactic thin disk. (5) Some sight lines had halos with observed X-ray scattering optical depth ?sca/AV that were signicantly different than expected. This may result from an inhomogeneous dust distribution across the halo extraction area.

Measurements of n-InGaAs with MBE layers: Relevance of negative magnetoresistance in the investigated samples

Measurements of nH were performed. nH values showed a distinct increase at temperatures below ~90K (1.1μm n-InGaAs samples) and a decrease at temperatures below ~30K (7μm n-InGaAs samples), depending on the doping level. These trends might be related to the magnetoresistance (MR) of the n-InGaAs samples. The MR behavior of the n-InGaAs samples with respect to magnetic field and temperature was apparently dependent on the doping level. Two n-InGaAs samples, one of which had a thin InGaAs epilayer (1.1μm) and the other with a thicker (7μm) epilayer, showed interesting behavior at low temperature. Their behavior at magnetic fields of approximately −15000 to +15,000G were determined. The resistivity ((ρG – ρ0)/ρ0) of the 1.1μm sample was negative at temperatures lower than 30K.

Finite element and network electrical simulation of rotating magnetofluid flow in nonlinear porous media with inclined magnetic field and hall currents

A mathematical model is presented for viscous hydromagnetic flow through a hybrid non-Darcy porous media rotating generator. The system is simulated as steady, incompressible flow through a nonlinear porous regime intercalated between parallel plates of the generator in a rotating frame of reference in the presence of a strong, inclined magnetic field A pressure gradient term is included which is a function of the longitudinal coordinate. The general equations for rotating viscous magnetohydrodynamic flow are presented and neglecting convective acceleration effects, the two-dimensional viscous flow equations are derived incorporating current density components, porous media drag effects, Lorentz drag force components and Hall current effects. Using an appropriate group of dimensionless variables, the momentum equations for primary and secondary flow are rendered nondimensional and shown to be controlled by six physical parameters-Hartmann number (Ha), Hall current parameter (Nh), Darcy number (Da), Forchheimer number (Fs), Ekman number (Ek) and dimensionless pressure gradient parameter (Np), in addition to one geometric parameter-the orientation of the applied magnetic field (? ). Several special cases are extracted from the general model, including the non-porous case studied earlier by Ghosh and Pop (2006). A numerical solution is presented to the nonlinear coupled ordinary differential equations using both the Network Simulation Method and Finite Element Method, achieving excellent agreement. Additionally very good agreement is also obtained with the earlier analytical solutions of Ghosh and Pop (2006). for selected Ha, Ek and Nh values. We examine in detail the effects of magnetic field, rotation, Hall current, bulk porous matrix drag, second order porous impedance, pressure gradient and magnetic field inclination on primary and secondary velocity distributions and also frictional shear stresses at the plates. Primary velocity is seen to decrease with an increase in Hall current parameter (Nh) with the converse observed for the secondary velocity.