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Two-dimensional (2D) transition metal dichalcogenide (TMD) monolayers have currently been of immense interest in materials research because of their versatility, and tunable electronic and magnetic properties. In this study, we systematically studied the electronic and magnetic properties in pristine and hydrogenated 1T, 1T’, and 2H TMD monolayers. We found Group IV (Ti, Zr, and Hf), VI (Cr, Mo, and W), and X (Ni, Pd, and Pt) pristine TMD monolayers, respectively, mostly adopted 1T, 2H, and 1T as their stable structures, except for WTe2 which exhibits 1T’. The stable 1T’ structure only exists for pristine WTe2 and it had been identified as a topological insulator with a band gap of 0.11 eV. Upon hydrogenation, a structural phase transition occurred from 1T to 2H in Group IV, while for Group X, the stable structure remained 1T. For Group VI, the stable phase transitioned from 1T to 2H or 1T’ phases. Moreover, we found nineteen 2D magnetic materials through hydrogenation. Finally, further exploration of band topologies under hybrid functional calculations revealed that four of these identified magnetic monolayer structures exhibit quantum anomalous Hall effect. Our findings show that hydrogenated TMDs provide a new ground in searching for materials which have the potential for spintronics applications.

Background Proximal venous outflow obstruction (PVOO) in the abdomen and pelvis is increasingly recognized as an important contributor to venous disease of the lower extremity. There are currently no guidelines regarding a noninvasive screening tool for PVOO, although magnetic resonance venography (MRV) is commonly used in many practices. The objective of this study was to determine the value and utility of MRV in diagnosis and screening for PVOO. Methods This retrospective study consisted of 46 consecutive patients, all of whom presented with signs and/or symptoms of PVOO and were evaluated with MRV followed by intravascular ultrasound (IVUS) and venography. Of these 46 patients suspected to have PVOO based on clinical evaluation, 24 patients had PVOO confirmed with IVUS and venography and PVOO was not observed on IVUS and venography in the remaining 22 patients. The MRV of these 46 patients was retrospectively reviewed in a blinded fashion and then correlated with IVUS and venography by 1 vascular surgeon. A scoring system was developed to define the types of radiography findings that were observed: normal, suspicious, and abnormal. Results When compared with IVUS and multiplane venography, the interpretation of MRV had a sensitivity of 100% and a specificity of 22.7%. The positive predictive value of MRV was 58.5%, and the negative predictive value was 100%. Conclusions The high sensitivity (100%) and low specificity (22.7%) of MRV suggest that it can be a screening tool at best, used only to rule out PVOO; it cannot be used to confirm PVOO, given its a 41.5% false positive rate. Thus, the development of a different, noninvasive diagnostic test that can more accurately assess patients with suspected PVOO during the initial evaluation of their lower-extremity venous disease should be explored.

The development of super continuum sources is driven by the requirements of a wide range of emerging applications. This paper points out how non-silica fibers are of benefit not only because their broad mid-IR transparency enables continuum generation in the 2–5µm region but also since the high intrinsic nonlinearity of the glasses reduces the power-threshold for devices at wavelengths below 2µm. For these glasses, the material zero-dispersion wavelength is typically shifted to long wavelengths compared to silica so dispersion tailoring is key to creating sources based on practical, near-IR, solid state pump lasers. We show how modeling work has produced fiber designs that provide flattened dispersion profiles with high nonlinearity coefficients and zero-dispersion wavelengths in the near-IR. Building on this flexibility, modeling of the pulse dynamics then demonstrates how coherent mid-IR supercontinuum sources could be developed. We also show the importance of the second zero-dispersion wavelength using bismuth fibers as an example. Nonlinear mode-coupling is shown to be a factor in larger core fibers for high-power applications. Demonstrations of supercontinuum in microstructured tellurite fibers, all-solid lead–silicate (SF57) fibers and in bismuth fibers and tapers are then reported to show what has been achieved experimentally using a range of materials and fiber geometries.

Recent studies have shown that obesity is associated with an increased risk of fracture in both adults and children. It has been suggested that, despite greater bone size, obese individuals may have reduced true volumetric density; however this is difficult to assess using two dimensional techniques such as DXA. We evaluated the relationship between fat mass, and bone size and density, in a population cohort of children in whom DXA and pQCT measurements had been acquired.We recruited 530 children at 6years old from the Southampton Women's Survey. The children underwent measurement of bone mass at the whole body, lumbar spine and hip, together with body composition, by DXA (Hologic Discovery, Hologic Inc., Bedford, MA, USA). In addition 132 of these children underwent pQCT measurements at the tibia (Stratec XCT2000, Stratec Biomedical Systems, Birkenfeld, Germany).Significant positive associations were observed between total fat mass and both bone area (BA) and bone mineral content (BMC) at the whole body minus head, lumbar spine and hip sites (all p

Alterations in expression of the imprinted gene PHLDA2 are linked to low birth weight in both humans and the mouse. However birth weight is a summary measure of fetal growth and provides little information on the growth rate of the fetus in early and late pregnancy. To examine the relation of PHLDA2 expression with rates of fetal growth and explore associations with the infant's body composition in early childhood, we measured PHLDA2 mRNA levels in the term placenta of 102 infants whose mothers were participating in the Southampton Women's Survey (SWS). Higher PHLDA2 expression was associated with a lower fetal femur growth velocity between 19 and 34 weeks gestation. In addition, higher placental PHLDA2 gene expression was associated with a lower child's bone mineral content at four years of age, measured using dual-energy X-ray absorptiometry. The results suggest that placental PHLDA2 may provide a biomarker for suboptimal skeletal growth in pregnancies uncomplicated by overt fetal growth restriction., Highlights ► We examined placental PHLDA2 expression in 102 pregnancies. ► Identified negative correlation between placental PHLDA2 and fetal femur growth. ► Identified negative correlation between placental PHLDA2 and bone density at 4 years. ► Placental PHLDA2 may provide a biomarker for suboptimal skeletal growth.

The use of a helium ion microscope with an integrated gas injection system for nanofabrication is explored by demonstrating the milling of fine features into single layered graphene and the controlled deposition of tungsten and platinum wires from gaseous precursors. Using pattern generator software to control the path of the beam, nanoelectronic device designs are transferred directly into graphene. Four point contact designs are also defined on SiO"2/Si surfaces with atomic force microscopy used to characterize the resulting depositions. Although further optimization of the processes is required and questions of beam-induced damage to the delicate graphene lattice are yet to be answered, the helium ion microscope shows potential to go beyond what is possible with Ga^+ focused ion beam technologies in nanoscale device fabrication.

In this paper we present an analytical methodology to evaluate the response of a gas sensor based on correlation spectroscopy using a Fabry-Perot Interferometer (FPI). Here we consider a FPI which is illuminated with a converging beam from a black-body source. It is shown that the optimal FPI cavity length and reflectivity can be easily determined. We designed and tested three different gas sensors (CO, CO2, and CH4) using this methodology. Our numerical results are fully supported by experimental measurements.

Our specific aim was to investigate whether a local static magnetic field of a permanent magnet, of either pole, affects resting skin blood perfusion. This was done by measuring skin blood perfusion (SBF) by laser-Doppler in dorsum skin of 2nd and 4th fingers of the nondominant hands of 12 volunteers. Both fingers were first exposed to sham magnets, and then the 2nd finger was exposed alternately to north and south poles of a neodymium magnet that produced a field of 4024 G at the palmar part of the finger and a field of 879 +/- 52 G at the site of finger dorsum SBF measurement. Each of the three exposure intervals was 15 min. SBF values were analyzed by first computing the average SBF during the last 5 min of each of the three 15-min exposure intervals. These SBF averages were initially tested for magnet or magnet-pole effects by analysis of variance for repeated measures with finger as a factor, using SBF values for each finger as the test variable. Results of this analysis revealed a large variability in finger SBF among subjects and no significant difference in SBF between exposure conditions (P = 0.705) or any significant interaction between SBF and finger (P = 0.396). However, when intersubject variability was reduced by using the flow difference between treated and nontreated fingers in each exposure interval as the test variable, a statistically significant effect (P = 0.016) attributable to magnet exposure was uncovered. This effect was a reduction in resting SBF in the magnet-exposed fingers that was similar for north and south pole magnet exposure. The present findings are the first to demonstrate a direct effect of locally applied magnets on human skin blood perfusion.

In this work we determine the thermo-optical properties of two chalcogenide glasses (in mol%): 65 Ga 2 S 3 ; 30 La 2 S 3 ; 5 La 2 O 3 (Ga:La:S) and 72.5 Ga 2 S 3 ; 27.5 La 2 O 3 (Ga:La:S:O). The thermal relaxation calorimetry and the thermal lens technique were combined so that the samples specific heat, thermal diffusivity, thermal conductivity, and the temperature coefficient of the optical path length change could be measured. Our results indicate that changes in thermal diffusivity (∼2.7 × 10 −3 cm 2 /s) and conductivity (∼4.8 × 10 −3 W/K cm) observed when La 2 O 3 is added in the glass compounds are less than the error in the data.

The optical absorption of bulk Ga:La:S and Ga:La:S:O glasses in the near infrared was investigated by laser calorimetry using the free-electron laser source at the Thomas Jefferson National Accelerator Facility. An absorption coefficient of 1.2 × 10-2 and 2.3 × 10-2 cm-1 was measured at 1.55µm for Ga:La:S and Ga:La:S:O respectively. Comparing this result with conventional transmission measurements, we show that absorption is the prevailing loss mechanism in the near-IR region. Although not conclusive, our measurements suggest that the absorption is due to impurities and to the weak absorption tail.

As the science of wound healing has evolved over the past two decades, so has awareness of the "hidden epidemic" of lymphedema. Substantial information has been accumulated regarding the pathophysiology and therapy of lymphedema. Until recently, the relationship between wound healing and the negative effects of associated peri-wound lymphedema has received little attention. Identifying wound-related lymph stasis and safe mobilization of the fluid are fundamentals that must be addressed for proper therapy. Experience gained from the successful treatment of primary and secondary lymphedema has proven very useful in the applications to wound-related lymphedema. The mobilization of lymph fluid from the peri-wound area with the use of reasoned compression is essential for proper therapy of the open wound, as are appropriate bandage selection and safeguards for bandage application.

A rapid and deep inspiration triggers a sympathetically mediated transient vasoconstriction of skin arterioles (inspiratory gasp vascular response, IGVR). Because the IGVR has been most often measured and studied in skin that is rich in arteriovenous anastomoses (AVAs), such as the palmar aspect of the distal phalanx or plantar aspect of the toes, there is little information on its features in skin areas not dominated by thermoregulatory AVAs. Thus, the dependence of the magnitude of the IGVR on AVAs is unclear. We reasoned that if responses in a region of low AVA density, such as the finger dorsum distal phalanx, were comparable to those in AVA-rich skin, this would clarify the issue. Further, it might then be possible to use such areas to provide a useful complementary target for future study of sympathetically induced vasoconstriction. To test this, we determined the features of the finger dorsum IGVR in 28 healthy volunteers (age 19–57 years, 14 males) in whom distal phalanx skin blood perfusion (SBF) was monitored by laser–Doppler during 21 sequential IGVRs, each separated by 2 min. IGVR was quantified as the minimum SBF during each IGVR, expressed as a percentage of each immediately preceding 2-min SBF average. Results (mean ± SD) revealed an overall IGVR of 72.2 ± 16.7%, which is very near that reported from studies on the AVA-rich palmar finger pad. We therefore conclude that the IGVR does not depend on the presence of AVAs and that the dorsal distal phalanx is a viable alternative for the study of sympathetically related neurovascular responses.

In this paper, we demonstrate the application of a novel solid state modulator in monitoring the concentration of a test gas. A widespread cost-effective method of gas concentration monitoring currently uses a blackbody source and pyroelectric detector combined with a filter to isolate the required infrared spectral region. Presently the intensity on the detector is modulated by either a mechanical chopper or by electrically-pulsing the source. The device described by this work uses a continuously-driven blackbody source with a novel solid state infrared modulator operating in the 8-14 µm band to generate the required change in intensity on the pyroelectric detector, eliminating the need for moving parts. The modulator may be incorporated into the detector’s optical window in a more-compact future device. The modulator operation is outlined, and the results of determining the concentration of SF6 test gas in a dedicated cell are compared for the solid state modulator and a mechanical chopper.

Preliminary results are presented on a measurement technique for determination of water penetration into fibre optic sensors under high pressure, high temperature conditions. Both fibre optic sensors and communication fibres were subjected to prolonged treatment in heavy water at temperatures up to 250°C and pressures of 40 bar. Deuterium penetration is measured by a nuclear reaction technique based on a 3He micro-focussed ion beam, which permits two-dimensional mapping of the deuterium penetration into cleaved fibres. Water penetration can be detected whilst still confined to the cladding, well before any optical effects become apparent, permitting prediction of likely fibre lifetime under down-hole conditions after realistic experimental times.

A complete spectroscopic evaluation of rare earth-doped PBr3/AlBr3/SbBr3 has been carried out for several of the lanthanides. A comprehensive assignment of 4f energy levels has been made and absorption and fluorescence spectra have been used in evaluating the Judd–Ofelt parameters for most of the rare earths studied. The stimulated emission cross sections for the 4F3/2–4I11/2 transition in the neodymium-doped solution was found to be σNd=6.8 × 10−20 cm2, and for the 4I13/2–4I15/2 transition in the erbium-doped solution σEr=6.2 × 10−21 cm2. Non-radiative relaxation rates and stimulated emission cross sections have also been evaluated for potential laser transitions in the 3–5 μm spectral region.

Lead germanate thin films have been grown on BK7 and silica substrates, using pulsed excimer laser deposition (PLD) at wavelengths of 193 and 248 nm, from a bulk lead germanate target under various partial pressures of oxygen. The films produced vary in colour from brown, through clear, to yellow, and a parametric study has been undertaken of the film properties as a function of the growth conditions. The measured losses of the lead germanate films grown on glass substrates varied from ~ 2.5 to 7 dB /cm depending on the oxygen partial pressure used.

The effect of structural inhomogeneities in multi-quantum-well lasers caused by composition and well width fluctuations on the line-shape and gain of the lasers is discussed based on gaussian and uniform distribution models. Quantitative results of wide applicability are deduced. The results show that the structural inhomogeneities will reduce the gain and broaden the lineshape.

This paper describes the optical properties of GLS thin films deposited by laser ablation technique. These results complement the structural and compositional data on the same specimens reported in the preceding papers. A systematic investigation of the energy dependence of the refractive index, optical absorption edge, Urbach edge and optical gap has been carried out as a function of increasing deposition energy density. The optical absorption coefficient as a function of photon energy, deduced from transmission (T) and reflection (R) measurements, shows a very large shift of the edge towards lower energies relative to that of bulk glass with increasing deposition energy density. The optical gap, as determined by Taut extrapolation, and Urbach parameter have been determined as a function of deposition energy density. The changes in optical properties are correlated with the structural data

It is well known that the angular alignment tolerance for Brewsters angle plates is not generally strict. It is often not appreciated that for high index plates however wedge tolerances are small. It is shown that in Brewster angle plates of high refractive index materials, small wedge angles in the fabricated plate can cause internal s-plane reflections to become trapped by total internal reflection. A wedge angle acceptable in terms of its p-plane loss can cause such trapped reflections. In laser systems the resulting multiply reflected beams can move sideways in the plate and eventually hit o-ring seals or other mounting arrangements, causing component damage and leaks in unexpected locations. Stray light problems of an unexpected nature can occur from this effect in both laser based and conventional optical devices.

Lower extremity transcutaneous oxygen tension (TcPO2) is used as a diagnostic and prognostic indicator of tissue perfusion and is reduced in diabetes mellitus. Since cardiac output, leg blood flow and microvascular perfusion each can singly or jointly effect tissue oxygenation, the relative importance of macro- vs microvascular factors has not been resolved. To clarify this issue we compared TcPO2 levels in diabetic and nondiabetic subjects in whom cardiac output, leg pulsatile blood flow, and microcirculatory perfusion parameters were noninvasively measured. In 60 diabetic and 60 nondiabetic subjects the following measurements were done on both legs during a single session evaluation: foot dorsum TcPO2 at 457, skin microvascular perfusion reserve (MVR) in response to local thermal provocation from 35 to 457 using laser-Doppler, anklebrachial index using Doppler ultrasound (ABI), and pulsatile leg blood flow using magnetic resonance flowmetry; cardiac output was determined using transthoracic bioimpedance. The diabetic and nondiabetic groups were determined to have nonsignificant differences (mean{ SEM, DM vs NODM) with respect to age (63.3{ 1.1 vs 60.1 { 1.5 years), cardiac output (5.5 { 0.2 vs 5.5 { 0.2 l/min), leg blood flow (1.6 { 0.05 vs 1.7 { 0.06 ml/min/100 cc) and ABI. Although macrocirculatory values were equivalent, microvascular function indicators were significantly reduced in the diabetic group: TcPO2 (51.9{ 1.4 vs 62.9 { 1.3 mmHg); MVR (76.7 { 1.5 vs 84.9 { 0.9%) and were correlated only in diabetics (r 2 A 0.48, Po 0.001). The findings suggest a primary linkage between the diabetic TcPO2 deficit and the microcirculatory submaximal vasodilatory response, with little if any role of macrocirculatory factors. q 1996 Academic Press, Inc.