Berry paramagnetism in the Dirac semimetal ZrTe5

Dirac matters have attracted a lot of interest due to their unique band structure with linear band dispersions, which have great potential for technological applications. Recently, three-dimensional Dirac and Weyl semimetals have invoked distinctive phenomena originating from a non-trivial Berry phase. In this study, we prepare single crystals of TixZr1-xTe5 with a highly anisotropic Fermi surface. Our detailed electrical transport measurements reveal that the crystals show the Lifshitz transition, and Ti doping induces a band shift. Further quantum oscillation analyses demonstrate that the TixZr1-xTe5 crystals are 3D Dirac semimetals. Additionally, we observed a minimum temperature-dependent magnetic susceptibility, which is close to a peak position of electrical resistivity. This observation is interpreted in terms of the Berry paramagnetism. Our finding paves the way to determine a band topology by magnetism and also provides a platform to apply the Berry magnetism to Dirac semimetals.

Thin Films of Nanocrystalline Fe(pz)[Pt(CN)4] Deposited by Resonant Matrix-Assisted Pulsed Laser Evaporation

Prior studies of the thin film deposition of the metal-organic compound of Fe(pz)Pt[CN]4 (pz = pyrazine) using the matrix-assisted pulsed laser evaporation (MAPLE) method, provided evidence for laser-induced decomposition of the molecular structure resulting in a significant downshift of the spin transition temperature. In this work we report new results obtained with a tunable pulsed laser, adjusted to water resonance absorption band with a maximum at 3080 nm, instead of 1064 nm laser, to overcome limitations related to laser–target interactions. Using this approach, we obtain uniform and functional thin films of Fe(pz)Pt[CN]4 nanoparticles with an average thickness of 135 nm on Si and/or glass substrates. X-ray diffraction measurements show the crystalline structure of the film identical to that of the reference material. The temperature-dependent Raman spectroscopy indicates the spin transition in the temperature range of 275 to 290 K with 15 ± 3 K hysteresis. This result is confirmed by UV-Vis spectroscopy revealing an absorption band shift from 492 to 550 nm related to metal-to-ligand-charge-transfer (MLCT) for high and low spin states, respectively. Spin crossover is also observed with X-ray absorption spectroscopy, but due to soft X-ray-induced excited spin state trapping (SOXIESST) the transition is not complete and shifted towards lower temperatures.

Detecting cadmium contamination in loessal soils using near-infrared spectroscopy in the Xiaoqinling gold area

Loess is an important soil type that is widespread in the Loess Plateau of northwest China. However, mining exploitation, beneficiation, and metallurgy have led to inorganic contamination of soils that threatens the health of residents. The regular absorption peak shift of near-infrared (NIR) spectra in loessal soils represents a new method of soil environmental assessment based on field reflectance spectroscopy and hyperspectral remote sensing. Specifically, the NIR features of loessal soil will shift in response to changes in the soil composition and microstructure induced by heavy metal pollution. This study collected 27 samples from notable regions in the study area. Mid-infrared (MIR) spectral analysis, NIR spectral analysis, modified seven-step Tessier sequential extraction, and X-ray diffraction were used to analyze the band shift phenomenon of MIR and NIR features. The alignment of NIR bands was determined via the correlation between NIR and MIR bands associated with the vibration variations of the hydroxyl group. The correlations established by NIR band positions and exchangeable Cd cations were also analyzed. The results were then discussed according to the mineralogical characteristics of the heavy metal cations adsorbed on the surface and interlayer sites of clay minerals. These results can be used as a reference for the application of NIR technology to detecting heavy metal contamination in the soil of mining regions.

Temperature Dependences of IR Spectra of Humic Substances of Brown Coal

The capabilities of temperature-monitored IR spectroscopy for studying the organic matter and mineral composition of humic substances (HS) were tested. Temperature dependences of the mid-IR spectra of humic substances heated in the air in the range 25–215 °C (298–488 K, with a step of 2.5 °C)—for three commercially available samples isolated from brown coal (leonardite)—were performed. The characteristic bands were identified, and their changes in band maxima positions and intensities were compared. From the viewpoint of interpretation of HS components, the spectra were divided into regions of quartz lattice region (800–260 cm−1), quartz overtone region (1270–800 cm−1), humic substance organic matter region (1780–1270 cm−1), quartz combination region (2800–1780 cm−1), CH-speciation region (3100–2800 cm−1), and hydrogen-speciation region (4000–3100 cm−1) thus selected to contain the dominating type of bands. For the first time, a reversible change in the frequencies of the band maxima in IR spectra upon heating was observed, which can be interpreted as forming structures with a particular order in the studied humic substances in the dry state. For a single sample, both the band-shift scale and the functional dependence of the various bands on temperature differ significantly. The approach differentiates crystalline quartz bands, amorphous silica, and HSOM/surface groups experiencing a different temperature behavior of the band maxima and their intensities. Band-maximum temperature dependence can be considered more stable to changes in experimental conditions than band maxima at a single temperature, thus providing a more detailed HS structure analysis without HS decomposition or destruction.

Two-Step Facile Preparation of 2D MoS2/ZnO Nanocomposite p - n Junctions with Enhanced Photoelectric Performance

Both p - n and n - p heterojunctions of ZnO-MoS2 have been fabricated in order to understand the performance of electron and hole transport properties in solar cells and a self-powered photodetector system. Atomically thin 2-dimensional (2D) MoS2 was prepared by using a spin coating method with controlled process times, whereas ZnO nanowires were prepared by using a plasma sputtering deposition technique. The nanoscale morphologies, composites, and photoelectric properties of nanocomposites were examined using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and micro-Raman scattering spectroscopy, respectively. 2D heteronanostructures have exhibited an enhanced performance as compared to single-material-based prototypes. In photovoltaic mode, n - p heterojunction of the ZnO-MoS2-based prototype appears to have much better photoelectric conversion efficiency than that in the case with p - n junction, indicating highly effective hole transport properties of 2D MoS2 materials. Both band broadening and band shift were observed. Furthermore, the bias, annealing, and synergistic effects on the generated photocurrents and the response times were evaluated. The newly designed prototype exhibits exceptional properties: a broadband spectral response, a high signal-to-noise ratio, and excellent stability.

Redox index of Cys-thiol residues of serum apolipoprotein E and its diagnostic potential

Background: The redox modulation of Cys-thiol participates in various pathophysiological processes. We explored the proper index for estimating the redox status of Cys-thiol of serum apolipoprotein E (apoE), named “redox-IDX-apoE,” which is necessary to understand the redox biology of age-related diseases. Methods: The fractions of the reduced form (red-), reversible oxidized form (roxi-), and irreversibly oxidized form (oxi-) apoE in serum, obtained from the patients with no apparent disease (controls, n=192) and with atherosclerosis and type 2 diabetes (patients, n=16), were measured by a band-shift assay using a maleimide compound. Redox-IDX-apoE candidates were determined by calculating the values of these fractions and the total apoE concentration. Results: Cys number of apoE significantly increased for the ratio of roxi-apoE to total-apoE (roxi/total) (E2/E3>E3/E3>E3/E4) but decreased for the ratios of red-apoE to roxi-apoE (red/roxi) and [red-apoE + oxi-apoE] to roxi-apoE ([red + oxi]/roxi) (E2/E3<E3/E3<E3/E4). Considering the subjects with apoE3/E3, these ratios were independent of age and sex. Roxi/total showed negative correlations with serum triglyceride (TG) and HbA1c levels, while both red/roxi and [red + oxi]/roxi showed significant positive correlations with them. However, red/roxi and [red + oxi]/roxi in patients were significantly lower than those in controls, although serum TG and HbA1c levels in the patients were significantly higher than those in controls. Conclusion: The redox status of serum apoE-Cys-thiol is closely involved in the metabolism of TG-rich lipoproteins and glucose. The appropriate use of redox-IDX-apoE could be helpful in the diagnosis and prognosis of age-related diseases and in understanding the underlying mechanisms.

Synthesis and Characterization of Pure and Nitrogen Doped Titanium Oxide Nanocrystallites for Visible Light Photocatalytic Applications

The pure and nitrogen doped titanium oxide (TiO2) nanocrystallites were synthesized using sol-gel technique. The synthesized nanoparticles were characterized to examine the microstructural, optical and photocatalytic properties. The XRD studies of pure and doped TiO2 showed the formation of polycrystalline tetragonal structure with anatase phase. The crystallite sizes were calculated and found to be 17 and 15 nm for the pure and N-doped TiO2, respectively. FTIR studies indicated that the N-doped TiO2 bands are stronger compared with pure TiO2, indicating the more hydroxyl groups. FESEM studies showed the uniform formation of TiO2 nanocrystallites and spherical in shape with agglomeration. The photoluminescence spectra of the samples show emission peaks, indicating the band to band shift having the energy gap of 2.9 eV. The photocatalytic performance of the nanocatalyst was studied using methylene blue dye under visible light irradiation for 90 min. The photocatalytic efficiency of 66.9% and 85.8% is obtained for the pure and N-doped TiO2, respectively.

Redox Index of Cys-Thiol Residues of Serum Apolipoprotein E and Its Diagnostic Potential

We explored the proper index for estimating the redox status of Cys-thiol of serum apolipoprotein E (apoE), named “redox-IDX-apoE,” which is necessary to understand the redox biology of age-related diseases, such as atherosclerosis. The fractions of reduced form (red-), reversible oxidized form (roxi-), and irreversibly oxidized form (oxi-) apoE were measured by a band-shift assay. Candidates of redox-IDX-apoE were determined by calculating the values of these fractions and total apoE concentration. The ratios of roxi-apoE to total-apoE (roxi/total), red-apoE to roxi-apoE (red/roxi), and [red-apoE + oxi-apoE] to roxi-apoE ([red + oxi]/roxi) were independent of age and sex. Roxi/total showed significant negative correlations with serum triglyceride (TG) and HbA1c levels, while red/roxi and [red + oxi]/roxi showed significant positive correlations with them. However, red/roxi and [red + oxi]/roxi in the patients with atherosclerosis were significantly lower than those in control subjects, although serum TG and HbA1c levels in the patients were significantly higher than those in controls. The redox status of serum apoE-Cys-thiol is closely involved in the metabolism of TG-rich lipoproteins and glucose and may vary depending on the difference in pathological conditions. The appropriate usage of these ratios could be helpful in the diagnosis and prognosis of age-related diseases.

Secondary metabolites profiling of Vernonia amygdalina Del. in response to copper-induced abiotic stress

Background: Vernonia amygdalina is a green leafy vegetable that grows in tropical Africa and popularly cultivated in the southern part of Nigeria for its economic, nutritional and ethnomedicine value.Aims: This study analysed the influence of copper-induced abiotic stress on the deoxyribonucleic acid and secondary metabolites of V. amygdalina.Setting: Analyses of plant material were carried out in the Department of Botany, Lagos State University.Methods: Deoxyribonucleic acid (DNA) extraction and Inter Simple Sequence Repeat (ISSR) amplification were performed. Copper (Cu) concentration in leaves and stem of V. amygdalina was determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES), secondary metabolites were determined using gas chromatography–mass spectrometry (GC-MS) and the effect on DNA amplification and profiling was analysed using gel electrophoresis.Results: After 41 days of cultivation, the stem of V. amygdalina significantly bioaccumulated 37 mg/L, 50 mg/L and 215 mg/L of Cu after spiking with 400 mg/L, 1000 mg/L and 2000 mg/L, respectively, whilst the leaves accumulated 52 mg/L, 100 mg/L and 350 mg/L of Cu, respectively. Copper-impregnated soil influenced phytochemicals of the plants by causing inconsistent increase and decrease in specific compounds such as levomenthol, methyl stearate and glycerine. Deoxyribonucleic acid bands of the stem and leaf of V. amygdalina from control site showed no band shift, whilst band shift occurred in the stem and leaf of the Cu-spiked V. amygdalina.Conclusion: This study revealed the leaves of V. amygdalina having higher Cu accumulation capacity than the stems. Also, Cu alters the quality and quantity of phytochemicals in plant parts.