Normal Band Research Articles

The cytoskeletal crosslinking protein MACF1 is dispensable for thrombus formation and hemostasis

Coordinated reorganization of cytoskeletal structures is critical for key aspects of platelet physiology. While several studies have addressed the role of microtubules and filamentous actin in platelet production and function, the significance of their crosstalk in these processes has been poorly investigated. The microtubule-actin cross-linking factor 1 (MACF1; synonym: Actin cross-linking factor 7, ACF7) is a member of the spectraplakin family, and one of the few proteins expressed in platelets, which possess actin and microtubule binding domains thereby facilitating actin-microtubule interaction and regulation. We used megakaryocyte- and platelet-specific Macf1 knockout (Macf1fl/fl, Pf4-Cre) mice to study the role of MACF1 in platelet production and function. MACF1 deficient mice displayed comparable platelet counts to control mice. Analysis of the platelet cytoskeletal ultrastructure revealed a normal marginal band and actin network. Platelet spreading on fibrinogen was slightly delayed but platelet activation and clot traction was unaffected. Ex vivo thrombus formation and mouse tail bleeding responses were similar between control and mutant mice. These results suggest that MACF1 is dispensable for thrombopoiesis, platelet activation, thrombus formation and the hemostatic function in mice.

Electronic Transport Evidence for Topological Nodal-Line Semimetals of ZrGeSe Single Crystals

Although the band topology of ZrGeSe has been studied via magnetic torque technique, the electronic transport behaviors related to the relativistic Fermions in ZrGeSe are still unknown. Here, we first report systematic electronic transport properties of high-quality ZrGeSe single crystals under magnetic fields up to 14 T. Resistivity plateaus of temperature dependent resistivity curves both in the presence and absence of magnetic fields as well as large, non-saturating magnetoresistance in low-temperature region were observed. By analyzing the temperature- and angular-dependent Shubnikov-de Haas oscillations and fitting it via the Lifshitz-Kosevich (LK) formula with the Berry phase being taken into account, we proved that Dirac fermions dominate the electronic transport behaviors of ZrGeSe and the presence of non-trivial Berry phase. First principles calculations demonstrate that ZrGeSe possesses Dirac bands and normal bands near Fermi surface, resulting in the observed magnetotransport phenomena. These results demonstrate that ZrGeSe is a topological nodal-line semimetal, which provides a fundamentally important platform to study the quantum physics of topological semimetals.

Coherent vs incoherent transport in holographic strange insulators

Holographic strange metals are known to have a power law resistivity rising with temperature, which is reminiscent of the strange metal phases in condensed matter systems. In some holographic models, however, the exponent of the power law in the resistivity can be negative. In this case one encounters phases with diverging resistivity at zero temperature: holographic strange insulators.These states arise as a result of translational symmetry breaking in the system, which can either be strong explicit and relevant in the IR, or spontaneous, but pinned by a small explicit source. In some regards, one can associate these two classes to the normal band insulators due to the strong ionic potential, and Mott insulator due to the commensurate lock in of the charge density wave.We study different features of these classes on the explicit example of a holographic helical model with homogeneous Bianchy VII type translational symmetry breaking, and uncover the main mechanisms underlying transport in these two cases. We find that while transport in the explicit relevant case is governed by the incoherent conductivity, in the pinned spontaneous case the leading contribution comes from the coherent part.

Voltage-tunable dual-band Ge/Si photodetector operating in VIS and NIR spectral range

Extending and controlling the spectral range of light detectors is very appealing for several sensing and imaging applications. Here we report on a normal incidence dual band photodetector operating in the visible and near infrared with a bias tunable spectral response. The device architecture is a germanium on silicon epitaxial structure made of two back-to-back connected photodiodes. The photodetectors show a broad photoresponse extending from 390nm to 1600nm with the capability to electronically select the shorter (400-1100 nm) or the longer (1000-1600 nm) portion with a relatively low applied voltage. Devices exhibit peak VIS and NIR responsivities of 0.33 and 0.63 A/W, respectively, a low optical crosstalk (<-30dB), a wide dynamic range (>120dB) and, thanks to their low voltage operation, maximum specific detectivities of 7·1011cmHz1/2/W and 2·1010cmHz1/2/W in the VIS and NIR, respectively.

Permutative k-exponential epigroups

We prove that any permutative k-exponential epigroup is a normal band of unipotent epigroups. Moreover, we describe the least regular congruence on such semigroups. Finally, we give an example of a permutative epigroup which is not a band of unipotent epigroups.

Design and Experimental Research of Movable Cable-Driven Lower Limb Rehabilitation Robot

Aiming at solving the problems of the existing lower limb rehabilitation robots on aspects of configuration limitations, human–machine compatibility, gravity compensation, and multimodal rehabilitation, a movable cable-driven lower limb rehabilitation robot (MCLR) is proposed in this paper, which can realize the gait training and walking training in passive mode, initiative mode, and assistive mode. First, the structure and working principle of MCLR is introduced. The traction type is further optimized. Second, the key control problems of the passive force servo system are analyzed in detail. In order to improve the loading accuracy and speed during the initiative training, the dynamic model of the cable-driven unit is established. Based on this model, an active force control strategy is proposed. Finally, the speed control strategy and the active force control strategy are studied experimentally. The experimental results show that the speed servo system has good tracking ability, which can meet the requirements of the passive rehabilitation. The active force control strategy can significantly improve the loading accuracy and the dynamic performance of the force servo system. The force servo system has good tracking ability in the normal rehabilitation frequency band, which can meet the requirements of the initiative rehabilitation.

Characterization and Mechanism Analysis of Growth Bands in Chemical Vapor Deposited ZnS

In the chemical vapor deposited zinc sulfide, it often appears obvious light and dark growth bands along the growth direction, which will affect the homogeneity of optical properties of CVD ZnS and the efficiency of subsequent heat treatment. X-ray diffraction, Metallographic microscope and SEM were used to detect the crystal structure, grain size and microstructure, and the concentration of Zn and S in different bands was tested by EDTA titration, XRF, ICP and HF-combustion IR absorption spectrometric method. Results: Compared to the normal band, the grain size in the bright band was significantly larger, and the concentration of hexagonal phase in the bright band was lower, while the concentration ratio of Zn and S in the CVD ZnS did not have the regularity in the different bands. Combining with relevant knowledge about characteristics of the deposition process and crystal growth theory, the paper analyzes the formation mechanism of growth bands in CVD ZnS, and find that the main factor is the mutation of the concentration of the reactants in the deposition surface, affect the crystal nucleation rate and growth rate, eventually lead to the different grain morphologies, and even showing up the macroscopic growth bands. Compared with the actual process parameters, we have confirmed it and found out the main causes of mutation of the reactant concentration, this will have important guiding significance to the improvement of product quality in the future.

Sign-alternating photoconductivity and magnetoresistance oscillations induced by terahertz radiation in HgTe quantum wells

We report on the observation of terahertz radiation induced photoconductivity and of terahertz analog of the microwave-induced resistance oscillations (MIRO) in HgTe-based quantum well (QW) structures of different width. The MIRO-like effect has been detected in QWs of 20 nm thickness with inverted band structure and a rather low mobility of about 3 $\times$ 10$^5$ cm$^2$/V s. In a number of other structures with QW widths ranging from 5 to 20 nm and lower mobility we observed an unconventional non-oscillatory photoconductivity signal which changes its sign upon magnetic field increase. This effect was observed in structures characterized by both normal and inverted band ordering, as well as in QWs with critical thickness and linear dispersion. In samples having Hall bar and Corbino geometries an increase of the magnetic field resulted in a single and double change of the sign of the photoresponse, respectively. We show that within the bolometric mechanism of the photoresponse these unusual features imply a non-monotonic behavior of the transport scattering rate, which should decrease (increase) with temperature for magnetic fields below (above) the certain value. This behavior is found to be consistent with the results of dark transport measurements of magnetoresistivity at different sample temperatures. Our experiments demonstrate that photoconductivity is a very sensitive probe of the temperature variations of the transport characteristics, even those that are hardly detectable using standard transport measurements.

Uncommon Finding of a Gastrointestinal Stromal Tumor in a Patient with Hyperechoic Liver Lesions - Case Report

Abstract Introduction: Hyperechoic liver lesions identified by conventional ultrasonography are diverse in underlying pathology and most of the time require further investigations. Gastrointestinal stromal tumors (GIST) are rare neoplasms of the gastrointestinal tract which are uncommonly found in metastatic stages at first presentation. Case report: We present the case of a 51 years old woman with nonspecific symptoms in which conventional ultrasonography showed hyperechoic lesions in the right lobe of the liver with a diameter up to 40 mm. Esophagogastroduodenoscopy revealed a submucosal tumor on the small curvature of the stomach, on the anterior wall, with central ulceration, with normal narrow band imaging (NBI) mucosal pattern and negative gastric biopsy. Contrast enhanced ultrasonography was performed, describing multiple lesions with inhomogeneous enhancement in the arterial phase and rapid washout at the end of arterial phase. Endoscopic ultrasound with fine needle aspiration (EUS-FNA) biopsy examination was definitive for the final diagnosis of epithelioid gastric gastrointestinal stromal tumor. The patient was diagnosed with T2N0M1 epithelioid gastric GIST, stage IV, and is currently under treatment with tyrosine kinase inhibitors. Conclusions: GIST represent a diagnostic challenge in medical practice because of its size, unusual location in the submucosal layer and lack of symptoms. The role of EUS-FNA is of paramount importance in increasing the accuracy of diagnosis in the case of GIST. The particularity in our case consists of the unusual presentation with the lack of specific symptoms and signs associated with the presence of metastatic lesions at the moment of the diagnosis of GIST.

Magnetooptics of HgTe/CdTe Quantum Wells with Giant Rashba Splitting in Magnetic Fields up to 34 T

The electron cyclotron resonance spectra in classical and quantizing magnetic fields in asymmetric heterostructures with HgCdTe/CdHgTe quantum wells with selective barrier doping are investigated. Self-consistent calculations of the energy spectra at B = 0 and Landau levels in the framework of the 8-band Kane model using the Hartree approximation are made. The strong (~10%) splitting of the cyclotron resonance line observed in weak fields is attributed to the Rashba effect in samples with inverted and normal band structures. The evolution of absorption lines upon a variation in the magnetic field is investigated up to 34 T, when the magnetic quantization already dominates over Rashba splitting.

Research on the normal spectral band emissivity of tungsten between 150 and 500 °C.

Tungsten is the baseline divertor material for a tokamak. Due to the effect of the interaction of plasma and the first wall, the first wall accumulates a large amount of heat flux and suffers irreversible damages. Therefore, the diagnosis of the first wall temperature of the tokamak by using a radiation thermometer is the premise to ensure the safe and stable operation of the whole facility. However, in order to achieve high precision of temperature measurement, the emissivity of tungsten must be measured accurately. In this paper, we built a set of emissivity measurement system and a method for accurate calculation of emissivity is proposed. This method effectively eliminated the interference of background radiation and improves the accuracy of emissivity measurement. By using this method, the author measured the emissivity of tungsten under the conditions of different surface roughness in the range of 150 °C-500 °C and discussed the uncertainty of the measurement at the end.

Large spin-orbit splitting in inversion layers on HgCdTe with an inverted band structure

This paper reports the study of the magneto-transport properties of a two-dimensional electron gas confined in inversion layers on HgCdTe with an inverted band structure. The magnetoresistance exhibits Shubnikov-de Hass oscillations, where beating patterns are observed at low magnetic field. This can be attributed to the zero-field spin splitting. By using the fast Fourier transformation of the observed beating patterns, the zero-field spin splitting energy is extracted. The extracted energy up to is obtained, which is far larger than that in inversion layers on HgCdTe with a normal band structure. This offers a route to realize a HgTe-based spintronic device that works at room temperature.

Bio and phyto-chemical effect of Amphora coffeaeformis extract against hepatic injury induced by paracetamol in rats.

Paracetamol is the most commonly used analgesic-antipyretic drugs. Its excess use causes an acute hepatotoxicity. It is well known that the Bacillariophyta alga Amphora coffeaeformis is rich in many photosynthetic pigments with antioxidant activities as well as a series of biologically active substances. The current work has been designed to study thephytochemical composition of different A. coffeaeformisalgal extracts to select the most effective one. It was verified that acetone A. coffeaeformis algal extract is rich in various pigments and polyphenolic compounds (β-carotene(9.31±0.06 mg·g-1), gallic acid(28.31 µg·g-1), catechin(38.08 µg·g-1) and p-coumaric acid(38.69 µg·g-1)). The pigments and phenolic profiles in acetone extract were determined in addition to isolation of β-carotene and fucoxanthin which exhibited free radical scavenging activity by 74.80% and 69.40%, respectively. Therefore, the highest total antioxidant capacity and free radical scavenging activity were noticed with this extract. Consequently,efficiency of thisalgal extract was evaluated against hepatic intoxication induced by paracetamol in rats. The biochemical measurements (liver functions and markers of oxidative stress) were assayed. Moreover, the native protein, lipid and calcium moieties of native protein patternsin addition tocatalase (CAT); peroxidases (POX); α- and β-esterase (EST) isoenzymes and genomic DNA patterns were electrophoretically detected in liver tissues. It was found thatparacetamol caused significant (P < 0.05) elevation in serum liver functions associatedwith decline in activities of the antioxidant enzymes in that tissues. Also, it caused alterations represented electrophoretically at qualitative level from variations in the bands number and arrangement. So that, the paracetamol treated group wasnoticed with the lowest similarity index (SI). In addition, it caused abnormalities at the quantitative level through variations in quantity of normal bands. Algal extract restored all the biochemical functions to normal levels in the algal extractsimult-treated and pre-treated groups. Furthermore, it exhibited ameliorative effect against the electrophoretic alterations through restoring the absent normal bands and hiding the abnormal ones and hence increasing the SI values especially in the extractsimult-treated group. Algal extract exhibited antagonistic effect against the hepatic injury and the deleterious effects induced by paracetamol in the extractsimult-treated group.

Identification of arsenic-tolerant and arsenic-sensitive rice (Oryza sativa L.) cultivars on the basis of arsenic accumulation assisted stress perception, morpho-biochemical responses, and alteration in genomic template stability.

Arsenic toxicity is the most commonly experienced challenge of rice plants due to irrigation with arsenic-polluted groundwater and their cultivation in water logging environment which poses threat to human health, particularly in Bangladesh and West Bengal (India). In the present study, hydroponically grown eight rice cultivars, viz., Bhutmuri, Kumargore, Binni, Vijaya, Tulsibhog, Badshabhog, Pusa basmati, and Swarnadhan, were screened for arsenic tolerance by using physiological and molecular parameters. Treatment with 25μM, 50μM, and 75μM arsenate resulted in dosage-based retardation in growth and water content in all the tested cultivars due to accumulation of total arsenic along with the enhanced activity of arsenate reductase with more severe effects exhibited in cvs. Swarnadhan, Pusa basmati, Badshabhog, and Tulsibhog. Arsenic sensitivity of rice cultivars was evaluated in terms of oxidative stress markers generation, antioxidant enzyme activities, and level of genotoxicity. Under arsenate-challenged conditions, the levels of oxidative stress markers, viz., H2O2, MDA, and proline, and activities of antioxidant enzymes, viz., SOD and CAT, along with the level of genotoxicity analyzed by RAPD profiling were altered in variable levels in all tested rice cultivars and showed a significant alteration in band patterns in arsenate-treated seedlings of cvs. Swarnadhan, Pusa basmati, Badshabhog, and Tulsibhog in terms of appearance of new bands and disappearance of normal bands that were presented in untreated seedlings led to reduction in genomic template stability due to their high susceptibility to arsenic toxicity. Cultivar- and dose-dependent alteration of parameters tested including the rate of As accumulation showed that cvs. Kumargore, Binni, and Vijaya, specially Bhutmuri, were characterized as arsenate tolerant and could be cultivated in arsenic-prone areas to minimize level of toxicity and potential health hazards.

On band orthodox semirings

A semiring S is called a band orthodox semiring if $$E^+(S)$$ of all additive idempotents of S is a band semiring. Here we show that every band orthodox semiring is a subdirect product of a left band orthodox semiring and a right band orthodox semiring. Also we introduce the concept of quasi-spined product of a left normal band semiring and a d-inversive semiring with respect to a distributive lattice to study the structure of left normal band orthodox semirings.

Phase Instability and Thermal Properties of Multilayered Vanadium Diselenide: DAC-Based High Pressure Studies

Two-dimensional layered trichalcogenides are of current research interest because of their robust opto-electronics, and thermal properties. Mechanical and phonon vibrational properties of these materials are of significant importance in the field of stress and thermal management. Here we report the pressure dependence of structural and phonon behaviors of high quality few-layers vanadium diselenide nano-sheets grown by hydrothermal method employing synchrotron x-rays and micro-Raman scattering techniques. The high crystalline nature of the nanosheets was examined using transmission electron microscopy. Synchrotron x-ray studies at high pressure (up to 22 GPa) using a diamond-anvil cell identify a displacive type phase transition to a low symmetry monoclinic phase (C2/m) around 7 GPa corroborated with the P-dependent Raman scattering results. Raman spectroscopic studies at high pressure (up to 34 GPa) identify two prominent Raman bands with symmetry Eg and A1g. Eg band at 207 cm-1 shows normal hardening and A1g band at 236 cm-1 softens. The first order pressure derivatives of these phonons at ambient phase (P-3m1) are found to be -3.547(2) and 0.388(6) cm-1/ GPa, respectively. Using the experimental mode Grüneisen parameter of Eg Raman mode, the in-plane thermal expansion coefficient of the titular compound at the ambient phase is estimated. The observed results are expected to be useful in calibration and performance of next generation nano-electronics and optical devices under extreme stress conditions. These experimental results corroborated with our ab-initio calculations will be presented in the ECS meeting.

Non-equilibrium electron transport induced by terahertz radiation in the topological and trivial phases of Hg1-x Cd x Te.

Terahertz photoconductivity in heterostructures based on n-type Hg1−xCdxTe epitaxial films both in the topological phase (x < 0.16, inverted band structure, zero band gap) and the trivial state (x > 0.16, normal band structure) has been studied. We show that both the positive photoresponse in films with x < 0.16 and the negative photoconductivity in samples with x > 0.16 have no low-energy threshold. The observed non-threshold positive photoconductivity is discussed in terms of a qualitative model that takes into account a 3D potential well and 2D topological Dirac states coexisting in a smooth topological heterojunction.

Experimental and Theoretical Investigations on Intermediate Band in Doped Nano-SnS2

Nano-SnS2 and Sn0.75X0.25S2 (X = Cr, Fe, Y) have been prepared by thermolysis method. Phase analysis of x-ray diffraction data confirmed the single-phase nature of all prepared samples, with some residual carbon contributing to the background. Rietveld refinement revealed high anisotropy in crystallite size, signifying a cylindrical structure for the particle shape, as confirmed by transmission electron microscopy. The refined occupancies obtained for the doped cations were found to be smaller than the nominal target doping ratio (25%). Fourier-transform infrared spectra showed presence of Sn–S bond in all samples. The energy was found to be 3.42 eV, 3.33 eV, 2.1 eV and 3.14 eV, and 3.62 eV for undoped SnS2 and when doped with Cr, Fe, and Y, respectively. Density functional theory calculations illustrated that Fe-doped SnS2 has two bandgaps [normal and intermediate (IB) bands]. Meanwhile, Sn0.75Fe0.25S2 sample showed anti-Stokes and an extra photoluminescence peak related to the newly created intermediate band (IB) inside the energy gap. On the other hand, pure SnS2 and Sn0.75X0.25S2 (X = Cr, Y) samples emitted four photoluminescence subspectra in ultraviolet, violet, and blue regions.

Representation of normal bands as semigroups of k-bi-ideals of a semiring

Here we show that every normal band N can be embedded into the normal band $$\mathcal {B(S)}$$ of all k-bi-ideals, the left part $$N/ \mathcal {R}$$ of N into the left normal band $$\mathcal {R(S)}$$ of all right k-ideals, the right part $$N/ \mathcal {L}$$ of N into the right normal band $$\mathcal {L(S)}$$ of all left k-ideals, and the greatest semilattice homomorphic image $$N/ \mathcal {J}$$ of N into the semilattice of all k-ideals of a same k-regular and intra k-regular semiring S.

Topological transitions in continuously deformed photonic crystals

We demonstrate that multiple topological transitions can occur, with high-sensitivity, by continuous change of the geometry of a simple 2D dielectric-frame photonic crystal consisting of circular air-holes. By changing the radii of the holes and/or the distance between them, multiple transitions between normal and topological photonic band gaps (PBGs) can appear. The time-reversal symmetric topological PBGs resemble the quantum spin-Hall insulator of electrons and have two counter-propagating edge states. We search for optimal topological transitions, i.e., sharp transitions sensitive to the geometry, and optimal topological PBGs, i.e., large PBGs with clean spectrum of edge states. Such optimizations reveal that dielectric-frame photonic crystals are promising for optical sensors and unidirectional waveguides.