Integrative Modulation of Magnetic Resonance Transverse and Longitudinal Relaxivity in a Cell-Viable Bimagnetic Ensemble, γ-Fe2O3@ZnFe2O4

The potential application of magnetic nanosystems as magnetic resonance imaging (MRI) contrast agents has been thoroughly investigated. This work seeks to attain robust MRI-contrast efficiency by designing an interacting landscape of a bimagnetic ensemble of zinc ferrite nanorods and maghemite nanoparticles, γ-Fe2O3@ZnFe2O4. Because of competing spin clusters and structural anisotropy triggered by isotropic γ-Fe2O3 and anisotropic ZnFe2O4, γ-Fe2O3@ZnFe2O4 undergoes the evolution of cluster spin-glass state as evident from the critical slowing down law. Such interacting γ-Fe2O3@ZnFe2O4 with spin flipping of 1.2 × 10-8 s and energy barrier of 8.2 × 10-14 erg reflects enhanced MRI-contrast signal. Additionally, γ-Fe2O3@ZnFe2O4 is cell-viable to noncancerous HEK 293 cell-line and shows no pro-tumorigenic activity as observed in MDA-MB-231, an extremely aggressive triple-negative breast cancer cell line. As a result, γ-Fe2O3@ZnFe2O4 is a feasible option for an MRI-contrast agent having longitudinal relaxivity, r1, of 0.46 s-1mM-1 and transverse relaxivity, r2, of 15.94 s-1mM-1, together with r2/r1 of 34.65 at 1.41 T up to a modest metal concentration of 0.1 mM. Hence, this study addresses an interacting isotropic/anisotropic framework with faster water proton decay in MR-relaxivity resulting in phantom signal amplification.

Novel Nano-Electroplating-Based Plasmonic Platform for Giant Emission Enhancement in Monolayer Semiconductors

Two-dimensional semiconductors such as monolayer MoS2 have attracted considerable attention owing to their exceptional electronic and optical characteristics. However, their practical application has been hindered by the limited light absorption resulting from atomically thin thickness and low quantum yield. A highly effective approach to address these limitations is by integrating subwavelength plasmonic nanostructures with monolayer semiconductors. In this study, we employed electron beam lithography and nanoelectroplating techniques to develop a gold nanodisc (AuND) array plasmonic platform. Monolayer MoS2 transferred on top of the AuND array yields up to 150-fold photoluminescence enhancement compared to a gold film without normalization with respect to plasmonic hot spots. In addition, the unique protocol of nanoelectroplating helps to get flat-top cylindrical discs which enable less tear during the delicate wet transfer of monolayer MoS2. We explain our experimental findings based on electromagnetic simulations.

Polarity-Tunable Photocurrent through Band Alignment Engineering in a High-Speed WSe2/SnSe2 Diode with Large Negative Responsivity

Excellent light-matter interaction and a wide range of thickness-tunable bandgaps in layered vdW materials coupled by the facile fabrication of heterostructures have enabled several avenues for optoelectronic applications. Realization of high photoresponsivity at fast switching speeds is a critical challenge for 2D optoelectronics to enable high-performance photodetection for optical communication. Moving away from conventional type-II heterostructure pn junctions towards a WSe₂/SnSe₂ type-III configuration, we leverage the steep change in tunneling current along with a light-induced heterointerface band shift to achieve high negative photoresponsivity, while the fast carrier transport under tunneling results in high speed. In addition, the photocurrent can be controllably switched from positive to negative values, with ∼10⁴× enhancement in responsivity, by engineering the band alignment from type-II to type-III using either the drain or the gate bias. This is further reinforced by electric-field dependent interlayer band structure calculations using density functional theory. The high negative responsivity of 2 × 10⁴ A/W and fast response time of ∼1 μs coupled with a polarity-tunable photocurrent can lead to the development of next-generation multifunctional optoelectronic devices.

Multi-Bit Analog Transmission Enabled by Electrostatically Reconfigurable Ambipolar and Anti-Ambipolar Transport

Various analog applications, such as phase switching, have been demonstrated using either ambipolar or anti-ambipolar transport in two-dimensional materials. However, the availability of only one transport mode severely limits the application scope and range. This work demonstrates electrostatically reconfigurable and tunable ambipolar and anti-ambipolar transport in the same field-effect transistor using a photoactive ambipolar WSe₂ channel with gate-controlled channel and Schottky barriers. This enables the realization of in-phase, out-of-phase, and double-frequency sinusoidal output signals under dark and illumination conditions. The output waveforms were used to generate phase-, frequency-, and amplitude-modulated analog schemes for 2- and 3-bit data transmission. Evaluation of all possible schemes for their power consumption, error probability, and implementation complexity highlights the importance of switching between ambipolar and anti-ambipolar modes of transport for best transmission performance. A dual-metal contact transistor with improved linearity for harmonic and excess power suppression demonstrates further performance enhancement. Generic device architecture and operation makes this work adaptable to any ambipolar material amenable to electrostatic control.

First-principles based simulations of electronic transmission in ReS2/WSe2 and ReS2/MoSe2 type-II vdW heterointerfaces

Electronic transmission in monolayer ReS\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2 and ReS\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2 based van der Waals (vdW) heterointerfaces are studied here. Since ReS\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2/WSe\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2 and ReS\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2/MoSe\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2 type-II vdW heterostructures are suitable for near infrared (NIR)/short-wave infrared (SWIR) photodetection, the role of interlayer coupling at the heterointerfaces is examined in this work. Besides, a detailed theoretical study is presented employing density functional theory (DFT) and nonequilibrium Green’s function (NEGF) combination to analyse the transmission spectra of the two-port devices with ReS\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2/WSe\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2 and ReS\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2/MoSe\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2 channels and compare the near-equilibrium conductance values. Single layer distorted 1T ReS\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2 exhibits formation of parallel chains of ‘Re’-‘Re’ bonds, leading to in-plane anisotropy. Owing to this structural anisotropy, the charge carrier transport is very much orientation dependent in ReS\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{2}$$\end{document}2. Therefore, this work is further extended to investigate the role of clusterized ‘Re’  atoms in electronic transmission.

All-Electrical High-Sensitivity, Low-Power Dual-Mode Gas Sensing and Recovery with a WSe2/MoS2 pn Heterodiode

Two-dimensional MoS₂ gas sensors have conventionally relied on a change in field-effect-transistor (FET) channel resistance or in the Schottky contact/pn homojunction barrier. We demonstrate an enhancement in sensitivity (6×) and dynamic response along with a reduction in detection limit (8×) and power (10⁴×) in a gate-tunable type-II WSe₂(p)/MoS₂(n) heterodiode gas sensor over an MoS₂ FET on the same flake. Measurements for varying NO₂ concentration, gate bias, and MoS₂ flake thickness, reinforced with first-principles calculations, indicate dual-mode operation due to (i) a series resistance-based exponential change in the high-bias thermionic current (high sensitivity), and (ii) a heterointerface carrier concentration-based linear change in near-zero-bias interlayer recombination current (low power) resulting in sub-100 μW/cm² power consumption. Fast and gate-bias tunable recovery enables an all-electrical, room-temperature dynamic operation. Coupled with the sensing of trinitrotoluene (TNT) molecules down to 80 ppb, this study highlights the potential of the WSe₂/MoS₂ pn heterojunction as a simple, low-overhead, and versatile chemical-sensing platform.

Enhanced responsivity and detectivity of fast WSe2 phototransistor using electrostatically tunable in-plane lateral p-n homojunction

Layered transition metal dichalcogenides have shown tremendous potential for photodetection due to their non-zero direct bandgaps, high light absorption coefficients and carrier mobilities, and ability to form atomically sharp and defect-free heterointerfaces. A critical and fundamental bottleneck in the realization of high performance detectors is their trap-dependent photoresponse that trades off responsivity with speed. This work demonstrates a facile method of attenuating this trade-off by nearly 2x through integration of a lateral, in-plane, electrostatically tunable p-n homojunction with a conventional WSe2 phototransistor. The tunable p-n junction allows modulation of the photocarrier population and width of the conducting channel independently from the phototransistor. Increased illumination current with the lateral p-n junction helps achieve responsivity enhancement upto 2.4x at nearly the same switching speed (14-16 µs) over a wide range of laser power (300 pW-33 nW). The added benefit of reduced dark current enhances specific detectivity (D*) by nearly 25x to yield a maximum measured flicker noise-limited D* of 1.1×1012 Jones. High responsivity of 170 A/W at 300 pW laser power along with the ability to detect sub-1 pW laser switching are demonstrated.

Electrically Tunable Room Temperature Hysteresis Crossover in Underlap MoS2 Field-Effect Transistors

Clockwise to anticlockwise hysteresis crossover in current-voltage transfer characteristics of field-effect transistors (FETs) with graphene and MoS₂ channels holds significant promise for nonvolatile memory applications. However, such crossovers have been shown to manifest only at high temperature. In this work, for the first time, we demonstrate room temperature hysteresis crossover in few-layer MoS₂ FETs using a gate-drain underlap design to induce a differential response from traps near the MoS₂-HfO₂ channel-gate dielectric interface, also referred to as border traps, to applied gate bias. The appearance of trap-driven anticlockwise hysteresis at high gate voltages in underlap FETs can be unambiguously attributed to the presence of an underlap since transistors with and without the underlap region were fabricated on the same MoS₂ channel flake. The underlap design also enables room temperature tuning of the anticlockwise hysteresis window (by 140×) as well as the crossover gate voltage (by 2.6×) with applied drain bias and underlap length. Comprehensive measurements of the transfer curves in ambient and vacuum conditions at varying sweep rates and temperatures (RT, 45 °C, and 65 °C) help segregate the quantitative contributions of adsorbates, interface traps, and bulk HfO₂ traps to the clockwise and anticlockwise hysteresis.

Near-Direct Bandgap WSe2/ReS2 Type-II pn Heterojunction for Enhanced Ultrafast Photodetection and High-Performance Photovoltaics

Pn heterojunctions comprising layered van der Waals (vdW) semiconductors have been used to demonstrate current-rectifiers, photodetectors, and photovoltaic devices. However, a direct or near-direct heterointerface bandgap for enhanced photogeneration in high light-absorbing few-layer vdW materials remains unexplored. In this work, for the first time, density functional theory calculations show that the heterointerface of few-layer group-6 transition metal dichalcogenide (TMD) WSe₂ with group-7 ReS₂ results in a sizable (0.7 eV) near-direct type-II bandgap. The interlayer IR bandgap is confirmed through IR photodetection, and microphotoluminescence measurements demonstrate type-II alignment. Few-layer flakes exhibit ultrafast response time (5 μs), high responsivity (3 A/W), and large photocurrent-generation and responsivity-enhancement at the hetero-overlap region (10-100×). Large open-circuit voltage of 0.64 V and short-circuit current of 2.6 μA enable high output electrical power. Finally, long-term air-stability and facile single contact metal fabrication process make the multifunctional few-layer WSe₂/ReS₂ heterostructure diode technologically promising for next-generation optoelectronics.

Accurate Threshold Voltage Reliability Evaluation of Thin Al2O3 Top-Gated Dielectric Black Phosphorous FETs Using Ultrafast Measurement Pulses

Few-layer black phosphorus (BP) has attracted significant interest in recent years due to electrical and photonic properties that are far superior to those of other two-dimensional layered semiconductors. The study of long term electrical stability and reliability of black phosphorus field effect transistors (BP-FETs) with technologically relevant thin, and device-selective, gate dielectrics, stressed under realistic (closer to operation) bias and measured using state-of-the-art ultrafast reliability characterization techniques, is essential for their qualification and use in different applications. In this work, air-stable BP-FETs with a thin top-gated dielectric (15 nm Al₂O₃, SiO₂ equivalent thickness of 5 nm) were fabricated and comprehensively characterized for threshold voltage ( V_th) instability under negative gate bias stress at various measurement delays ( t_m), stress biases ( V_GSTR), temperatures ( T), and stress times ( t_str) for the first time. Thin top-gated oxide enables low V_GSTR that is closer to the operating condition and ultrafast V_th measurements with low delay ( t_m = 10 μs, due to high drain current) that ensure minimal recovery. The resultant time kinetics of V_th degradation (Δ V_th) shows fast saturation at longer stress times and low-temperature activation energy. V_th instability in these top-gated devices is suggested to be dominated by hole trapping, which is modeled using first-order equations at different V_GSTR and T. It is shown that measurements using larger t_m show lower degradation magnitude that do not saturate due to recovery artifacts and give inaccurate estimation of hole trap densities. Conventional, thick, and global back-gated oxide BP-FETs were also fabricated and characterized for varying t_m (1 ms being the lowest due to a low drain current level for thick oxide), V_GSTR, and T to benchmark our top-gated results. Nonsaturating Δ V_th in the back-gated devices is shown to result from recovery artifacts due to the large t_m (1 ms and greater) values. Finally, using a V_GSTR and T-dependent first-order model, we show that the top-gated Al₂O₃ BP-FETs with scaled gate oxide thickness can match state-of-the-art Si reliability specifications at operating voltage and room/elevated temperature.

Janus nanoparticles for contrast enhancement of T1–T2 dual mode magnetic resonance imaging

MnFe₂O₄@MnO Janus nanoparticles efficiently enhances contrast of both T₁ and T₂ based MR Images.

Multilayer ReS2 Photodetectors with Gate Tunability for High Responsivity and High-Speed Applications

Rhenium disulfide (ReS₂) is an attractive candidate for photodetection applications owing to its thickness-independent direct band gap. Despite various photodetection studies using two-dimensional semiconductors, the trade-off between responsivity and response time under varying measurement conditions has not been studied in detail. This report presents a comprehensive study of the architectural, laser power and gate bias dependence of responsivity and speed in supported and suspended ReS₂ phototransistors. Photocurrent scans show uniform photogeneration across the entire channel because of enhanced optical absorption and a direct band gap in multilayer ReS₂. A high responsivity of 4 A W^-1 (at 50 ms response time) and a low response time of 20 μs (at 4 mA W^-1 responsivity) make this one of the fastest reported transition-metal dichalcogenide photodetectors. Occupancy of intrinsic (bulk ReS₂) and extrinsic (ReS₂/SiO₂ interface) traps is modulated using gate bias to demonstrate tunability of the response time (responsivity) over 4 orders (15×) of magnitude, highlighting the versatility of these photodetectors. Differences in the trap distributions of suspended and supported channel architectures, and their occupancy under different gate biases enable switching the dominant operating mechanism between either photogating or photoconduction. Further, a new metric that captures intrinsic photodetector performance by including the trade-off between its responsivity and speed, besides normalizing for the applied bias and geometry, is proposed and benchmarked for this work.

Enhanced stability and performance of few-layer black phosphorus transistors by electron beam irradiation

Few layer black phosphorus (BP) has recently emerged as a potential graphene analogue due to its high mobility and direct, appreciable, band gap. The fabrication and characterization of field effect transistors (FETs) involves exposure of the channel material to an electron beam (e-beam) in imaging techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and fabrication techniques like electron beam lithography (EBL). Despite this, the effect of e-beam irradiation on BP-FET performance has not been studied experimentally. In this work, we report the first experimental study on the impact of e-beam irradiation on BP-FETs. An electron beam is known to induce defects and structural changes in 2D materials like graphene, MoS2etc. resulting in the deterioration of the device quality. However, for BP-FETs, we observe an improvement in the on-current and carrier mobility (μ) along with a decrease in threshold voltage (Vth) on exposure to an e-beam with 15 keV energy for 80 seconds. These changes can be attributed to the capture of electrons by traps near the SiO2-BP interface and reduced BP surface roughness due to e-beam exposure. Hysteresis measurements and physical characterization (i.e. atomic force microscopy (AFM), X-ray photoelectron (XPS) and Raman spectroscopies) validate these mechanisms. Reduced hysteresis indicates occupation of the traps, AFM surface scans indicate reduced surface roughness and XPS data show a reduced phosphorus oxide (POx) peak immediately after exposure. Raman measurements indicate a probable structural change due to the interaction between e-beam and BP which could result in better stability.

Phase engineering of seamless heterophase homojunctions with co-existing 3R and 2H phases in WS2 monolayers

Self-organized semiconductor-semiconductor heterostructures (3R-2H) that coexist in atomically thin 2D monolayers forming homojunctions are of great importance for next-generation nanoelectronics and optoelectronics applications. Herein, we investigated the defect controlled growth of heterogeneous electronic structure within a single domain of monolayer WS₂ to enable in-plane homojunctions consisting of alternate 2H semiconducting and 3R semiconducting phases of WS₂. X-ray photoelectron, Raman, and photoluminescence spectroscopy along with fluorescence and Kelvin probe force microscopy imaging confirm the formation of homojunctions, enabling a direct correlation between chemical heterogeneity and electronic heterostructure in the atomically thin WS₂ monolayer. Quantitative analysis of phase fractions shows 59% stable 2H phase and 41% metastable 3R phase estimated over WS₂ flakes of different sizes. Time-resolved fluorescence lifetime imaging confirms distinct contrast between 2H and 3R phases with two distinct lifetimes of 3.2 ns and 1.1 ns, respectively. Kelvin probe force microscopy imaging revealed an abrupt change in the contact potential difference with a depletion width of ∼2.5 μm, capturing a difference in work function of ∼40 meV across the homojunction. Further, the thermal stability of coexisting phases and their temperature dependent optical behavior show a distinct difference among 2H and 3R phases. The investigated aspects of the controlled in plane growth of coexisting phases with seamless homojunctions, their properties, and their thermal stability will enable the development of nanoscale devices that are free from issues of lattice mismatch and grain boundaries.

Exciton Emission Intensity Modulation of Monolayer MoS2 via Au Plasmon Coupling

Modulation of photoluminescence of atomically thin transition metal dichalcogenide two-dimensional materials is critical for their integration in optoelectronic and photonic device applications. By coupling with different plasmonic array geometries, we have shown that the photoluminescence intensity can be enhanced and quenched in comparison with pristine monolayer MoS2. The enhanced exciton emission intensity can be further tuned by varying the angle of polarized incident excitation. Through controlled variation of the structural parameters of the plasmonic array in our experiment, we demonstrate modulation of the photoluminescence intensity from nearly fourfold quenching to approximately threefold enhancement. Our data indicates that the plasmonic resonance couples to optical fields at both, excitation and emission bands, and increases the spontaneous emission rate in a double spacing plasmonic array structure as compared with an equal spacing array structure. Furthermore our experimental results are supported by numerical as well as full electromagnetic wave simulations. This study can facilitate the incorporation of plasmon-enhanced transition metal dichalcogenide structures in photodetector, sensor and light emitter applications.

Few-Layer MoS₂ p-Type Devices Enabled by Selective Doping Using Low Energy Phosphorus Implantation

P-type doping of MoS2 has proved to be a significant bottleneck in the realization of fundamental devices such as p-n junction diodes and p-type transistors due to its intrinsic n-type behavior. We report a CMOS compatible, controllable and area selective phosphorus plasma immersion ion implantation (PIII) process for p-type doping of MoS2. Physical characterization using SIMS, AFM, XRD and Raman techniques was used to identify process conditions with reduced lattice defects as well as low surface damage and etching, 4X lower than previous plasma based doping reports for MoS2. A wide range of nondegenerate to degenerate p-type doping is demonstrated in MoS2 field effect transistors exhibiting dominant hole transport. Nearly ideal and air stable, lateral homogeneous p-n junction diodes with a gate-tunable rectification ratio as high as 2 × 10(4) are demonstrated using area selective doping. Comparison of XPS data from unimplanted and implanted MoS2 layers shows a shift of 0.67 eV toward lower binding energies for Mo and S peaks indicating p-type doping. First-principles calculations using density functional theory techniques confirm p-type doping due to charge transfer originating from substitutional as well as physisorbed phosphorus in top few layers of MoS2. Pre-existing sulfur vacancies are shown to enhance the doping level significantly.

Interfacial n-Doping Using an Ultrathin TiO2 Layer for Contact Resistance Reduction in MoS2

We demonstrate a low and constant effective Schottky barrier height (ΦB ∼ 40 meV) irrespective of the metal work function by introducing an ultrathin TiO2 ALD interfacial layer between various metals (Ti, Ni, Au, and Pd) and MoS2. Transmission line method devices with and without the contact TiO2 interfacial layer on the same MoS2 flake demonstrate reduced (24×) contact resistance (RC) in the presence of TiO2. The insertion of TiO2 at the source-drain contact interface results in significant improvement in the on-current and field effect mobility (up to 10×). The reduction in RC and ΦB has been explained through interfacial doping of MoS2 and validated by first-principles calculations, which indicate metallic behavior of the TiO2-MoS2 interface. Consistent with DFT results of interfacial doping, X-ray photoelectron spectroscopy (XPS) data also exhibit a 0.5 eV shift toward higher binding energies for Mo 3d and S 2p peaks in the presence of TiO2, indicating Fermi level movement toward the conduction band (n-type doping). Ultraviolet photoelectron spectroscopy (UPS) further corroborates the interfacial doping model, as MoS2 flakes capped with ultrathin TiO2 exhibit a reduction of 0.3 eV in the effective work function. Finally, a systematic comparison of the impact of selective doping with the TiO2 layer under the source-drain metal relative to that on top of the MoS2 channel shows a larger benefit for transistor performance from the reduction in source-drain contact resistance.

Evaluation of Glycemia Control Achieved by Glargine and Lispro Versus Detemir and Aspart Insulin Regimes in Type 2 Diabetics Undergoing Surgery

There is paucity of scientific literature regarding the clinical outcome of long lasting basal insulin and rapid acting mealtime insulin regimes in surgical situations although employed in non-surgical situations. This study has evaluated the clinical outcome of two subcutaneous split-mixed Glargine+Lispro and Detemir+Aspart insulin regimes in type 2 diabetics undergoing surgery.

Solution-processed poly(3,4-ethylenedioxythiophene) thin films as transparent conductors: effect of p-toluenesulfonic acid in dimethyl sulfoxide

Conductivity enhancement of thin transparent films based on poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) by a solution-processed route involving mixture of an organic acid and organic solvent is reported. The combined effect of p-toluenesulfonic acid and dimethyl sulfoxide on spin-coated films of PEDOT-PSS on glass substrates, prepared from its commercially available aqueous dispersion, was found to increase the conductivity of the PEDOT-PSS film to ∼3500 S·cm(-1) with a high transparency of at least 94%. Apart from conductivity and transparency measurements, the films were characterized by Raman, infrared, and X-ray photoelectron spectroscopy along with atomic force microscopy and secondary ion mass spectrometry. Combined results showed that the conductivity enhancement was due to doping, rearrangement of PEDOT particles owing to phase separation, and removal of PSS matrix throughout the depth of the film. The temperature dependence of the resistance for the treated films was found to be in accordance with one-dimensional variable range hopping, showing that treatment is effective in reducing energy barrier for interchain and interdomain charge hopping. Moreover, the treatment was found to be compatible with flexible poly(ethylene terephthalate) (PET) substrates as well. Apart from being potential candidates to replace inorganic transparent conducting oxide materials, the films exhibited stand-alone catalytic activity toward I(-)/I3(-) redox couple as well and successfully replaced platinum and fluorinated tin oxide as counter electrode in dye-sensitized solar cells.

A clinical study to compare the efficacy and safety of pregabalin sustained release formulation with pregabalin immediate release formulation in patients of diabetic peripheral neuropathic pain

OBJECTIVE

To compare the efficacy and safety of sustained release (SR) formulation of pregabalin with immediate release (IR) formulation in patient with diabetic peripheral neuropathic pain.

MATERIALS AND METHODS

In this open label, randomized, comparative, multicentric study, the primary efficacy measure was reduction in visual analogue scale (VAS) of short form McGill pain questionnaire (SF-MPQ) score from baseline to last visit. The secondary evaluation measures included reduction in SF-MPQ descriptive score and present pain intensity score and change in clinical global impression - improvement of illness (CGI-I) and clinical global impression - severity of illness (CGI-S) from baseline to last visit. Total duration of the study was 12 weeks. Safety evaluation was done by recording treatment emergent adverse events and laboratory investigations at baseline and end of treatment.

RESULTS

Of 265 randomized patients, 133 received pregabalin SR tablets and 132 pregabalin IR. Patients randomized to both treatments responded to respective treatments. The least square means of VAS score in both the groups were reduced significantly (P <0.01). Reduction in both groups was similar (P = ns). At the end of the trial in both the groups, there was a significant reduction in the SF-MPQ descriptive score (P <0.01), severity of illness as well as clinically significant improvement in the symptoms. Difference between the groups for CGI-I (P = 0.37) and CGI-S (P = 0.41) score was not statistically significant. Treatment in both the groups was found safe and well tolerated.

CONCLUSION

The study shows that the pregabalin SR is safe and effective in patients of diabetic peripheral neuropathic pain. The results of the study demonstrated that pregabalin SR has comparable efficacy and safety as pregabalin IR.

CYLD mutations in familial skin appendage tumours

BACKGROUND

Germ-line mutations in CYLD are found in patients with familial skin appendage tumours. The protein product functions as a deubiquitinase enzyme, which negatively regulates NF-kappaB and c-Jun N-terminal kinase signalling. Brooke-Spiegler syndrome (BSS) is characterised by cylindromas, trichoepitheliomas and spiradenomas, whereas in familial cylindromatosis (FC) patients present with cylindromas and in multiple familial trichoepitheliomas (MFT) with trichoepitheliomas as the only skin tumour type. Although described as distinct entities, recent studies suggest that they are within the spectrum of a single entity.

OBJECTIVE

To investigate the mutation spectrum of CYLD and possible genotype-phenotype correlations.

METHODS

25 families including 13 BSS, 3 FC, and 9 MFT families were examined and evaluated for mutations in the CYLD gene.

RESULTS

In total, 18 mutations in CYLD, including 6 novel mutations, were identified in 25 probands (72%). The mutation frequencies among distinct phenotypes were 85% for BSS, 100% for FC, and 44% for MFT. The majority of the mutations were insertions, deletions or nonsense mutations leading to formation of truncated proteins. All mutations were located between exons 9 to 20, encoding the NEMO binding site and the catalytic domain. Genotype-phenotype analysis failed to reveal a correlation between the types of mutations and their location within the gene and the patients' phenotypes and disease severity.

CONCLUSIONS

This study provides further evidence on the role of CYLD in the pathogenesis of skin appendage tumours characterised by cylindromas, trichoepitheliomas and/or spiradenomas, but the molecular mechanisms of CYLD in skin tumorigenesis and the reasons for phenotypic variability remain to be explored.

Angiotensin II-induced mesangial cell apoptosis: role of oxidative stress

BACKGROUND

Angiotensin II (ANG II) has been shown to play a role in the induction of glomerular injury. In the present study, we evaluated the effects of ANG II on mesangial cell apoptosis and the involved molecular mechanism.

MATERIALS AND METHODS

The effect of ANG II on apoptosis of mouse mesangial cells (MC) was evaluated by morphologic, DNA fragmentation and TUNEL assays. To evaluate the role of oxidative stress and involved mechanisms, we studied the effect of antioxidants, anti-TGF-beta antibody, inhibitors of nitric oxide synthase and modulators of cytosolic calcium/heme oxygenase (HO) activity. In addition, we studied the effect of ANG II on the generation of reactive oxygen species (ROS) by MCs.

RESULTS

ANG II promoted apoptosis of MCs in a dose dependent manner. This effect of ANG II was not only associated with ROS production, but also inhibited by antioxidants. Both Anti-TGF-beta antibody and propranolol inhibited ANG II-induced ROS generation and apoptosis. BAPTA inhibited both ANG II- and TGF-beta-induced apoptosis. On the other hand, thapsigargin stimulated MC apoptosis under basal as well as ANG II/TGF-beta stimulated states. ANG II receptor types 1 and 2 antagonists attenuated the proapoptotic effect of ANG II. Hemin inhibited but zinc protoporphyrin enhanced the proapoptotic effect of ANG II. Propranolol increased HO activity; whereas pre-treatment with propranolol prevented ANG II-induced apoptosis.

CONCLUSIONS

ANG II promotes MC apoptosis. This effect of ANG II is mediated through downstream signaling involving TGF-beta, phospholipase D, and Ca(2+), contributing to the activation of NADPH oxidase and generation of ROS. HO activity plays a modulatory role in ANG II- induced MC apoptosis.

ProFeel: low cost visual-haptic perceptualization of protein structure-structure alignments

We describe ProFeel, an application for exploring molecular data from protein structure-structure alignments using a force-feedback joystick. Protein structure analysis is a useful application for multimodal information perceptualization because researchers in this area typically use several independent measures in assessment. A system that allows the user to simultaneously evaluate different criteria would therefore be quite useful. Four variables are assigned three different haptic effects each to allow the user to discern twelve separate data values. The haptic representation is coupled with a traditional molecular graphics visual display.

Follicular carcinoma in a functioning struma ovarii

We describe a case of follicular carcinoma in a functioning struma ovarii, which presented as an ovarian mass in a patient who had undergone a near-total thyroidectomy for a benign lesion. She underwent bilateral salpingo-oophorectomy and received radiotherapy and L-thyroxine treatment with no evidence of metastases in 4 years follow-up.

PROMUSE: a system for multi-media data presentation of protein structural alignments

We present and evaluate PROMUSE: an integrated visualization/sonification system for analyzing pairwise protein structural alignments (superpositions of two protein structures in three-dimensional space). We also explore how the use of sound can enhance the perception and recognition of specific aspects of the local environment at given positions in the represented molecular structure. Sonification presents several opportunities to researchers. For those with visual impairment, data sonification can be a useful alternative to visualization. Sonification can further serve to improve understanding of information in several ways. One use for data sonification is in tasks such as background monitoring, in which case sounds can be used to indicate thresholding events. With PROMUSE, data represented visually may be enhanced or disambiguated by adding sound to the presentation. This aspect of data representation is particularly important for showing features that are difficult to represent visually, due to occlusion or other factors. Another feature of our system is that by representing some variables through sound and others visually, the amount of information that may be represented simultaneously is extended. Our tool aims to augment the power of data visualization rather than replace it. To maximize the utility of our sonifications to represent data, we employed musical voices and melodic components with unique characteristics. We also used sound effects such as panning a voice to the left or right speaker and changing its volume to maximize the individuality of the sonification elements. By making the sonification parameters distinct, we allow the user to focus on those portions of the sonification necessary to resolve possible ambiguities in the visual display. Sonifications of low level data such as raw protein or DNA sequences tend to sound random, and not very musical. We chose instead to sonify an analysis of data features, and thereby present a higher level view of the data. We also used brief melodic phrases rather than single notes in order to generate sounds that were more pleasing and musically idiomatic. To validate the utility of our system, we present the results of an experiment in which PROMUSE was used to test the use of sound as an aid for clarifying visual information. We also compare the overall effectiveness of visual versus aural information delivery.

Cortisol response to arginine-vasopressin does not compare with cortisol response to insulin-hypoglycemia in pituitary tumors

Timed cortisol responses to insulin-hypoglycemia (IH) and arginine-vasopressin (AVP) were compared in 16 patients with pituitary tumors and six healthy controls. Serum cortisol was estimated by a specific and sensitive radioimmunoassay as per the WHO protocol. The basal cortisol (AM) was normal (> 290 nmol/l) in 9 patients and low in seven. With IH peak cortisol response was normal (> 550 nmol/l) in 10 patients, 8 of whom had normal and 2 had low basal (AM) cortisol. In contrast AVP evoked normal cortisol responses in only 5 of these patients, all of whom had normal basal (AM) cortisol and none had low basal (AM) cortisol. The data indicate lower sensitivity for AVP stimulation test (50%) and favour IH as the standard cortisol stimulation test in patients with pituitary tumors awaiting surgery.

Assessing the hypothalamo-pituitary-adrenocortical axis using physiological doses of adrenocorticotropic hormone

We compared cortisol responses to 1 microgram adrenocorticotropic hormone (ACTH), 250 micrograms ACTH and insulin-induced hypoglycaemia (IIH), in patients suspected to have secondary hypocortisolism. Twenty-four patients (16 with hypothalamopituitary disorders and 8 on long-term glucocorticoid therapy) and eight healthy controls, underwent all three test protocols, with intervals of one day between each test. Mean cortisol responses to all three tests were comparable in both groups, but were more closely correlated for IIH vs. the 1 microgram ACTH test (r = 0.96) than for IIH vs. the 250 micrograms ACTH test (r = 0.88). Seven patients had discrepant results; all had a normal peak cortisol response to 250 micrograms ACTH (> 550 nmol/l), but a subnormal response to 1 microgram ACTH. Six of these also had a subnormal response to IIH. Cortisol responses to IIH match more closely those for 1 microgram ACTH in individual instances than those for 250 micrograms ACTH. The standard 250 micrograms ACTH stimulation, being supraphysiological, leads to underdiagnosis of the hypocortisolaemic state. The 1 microgram ACTH stimulation test should replace the standard 250 micrograms ACTH stimulation test in assessing the hypothalamo-pituitary-adrenocortical axis in secondary hypocortisolism.