Neutron diffraction study of the magnetic order in NdMn2Ge1.6Si0.4

Here we report a detailed investigation of NdMn2Ge1.6Si0.4; this forms part of our investigation of the magnetic order across the NdMn2Ge2−xSix (x = 0–2.0) series by magnetometry, x-ray diffraction and neutron diffraction over the temperature range 6–465 K. On decreasing the temperature from 465 K, NdMn2Ge1.6Si0.4 exhibits four magnetic transitions: (i) from paramagnetism to intralayer antiferromagnetism AFl at TIntraN ~ 430 K; (ii) AFl to canted ferromagnetism Fmc at TInterC ~ 330 K; (iii) Fmc to conical magnetic ordering of the Mn sublattice Fmi at Tcc ~ 178 K and (iv) Fmi(Mn) to Fmi(Mn)+F(Nd) at TNdC ~ 72 K

Magnetic properties and magnetocaloric effect of NdMn2−xTixSi2 compounds

The structural and magnetic properties of the intermetallic compounds NdMn2−xTixSi2(x = 0, 0.1, 0.2, and 0.3) have been studied by x-ray and high resolution neutron powder diffraction, specific heat, dc magnetization, and differential scanning calorimetry measurements over the temperature range 3–450 K. The Curie temperature and Néel temperature of NdMn2Si2 decrease from TC = 36 K and TN = 380 K to TC = 14 K and TN = 360 K, respectively, on substitution of Ti (x = 0.3) for Mn. The magnetocaloric effect at the first order ferromagnetic phase transition at TC, has been investigated in detail. Under a change of magnetic field of 0–5 T, the maximum value of the magnetic entropy change is 27 J kg−1 K−1 at x = 0, reducing to 15.3 J kg−1 K−1 at x = 0.1 and 10 J kg−1 K−1 at x = 0.3; importantly, no thermal or field hysteresis losses occur (eliminated from 0.3 K and 28.5 J kg−1 at x = 0 around TC) with increase in Ti concentration. Combined with the lack of any hysteresis effects, these findings indicate that NdMn1.9Ti0.1Si2 compound offers potential as a candidate for magnetic refrigerator applications in the temperature region below 35 K

Magnetic phase transitions and entropy change in layered NdMn1.7Cr0.3Si2

A giant magnetocaloric effect has been observed around the Curie temperature, TC ∼ 42 K, in NdMn1.7Cr0.3Si2 with no discernible thermal and magnetic hysteresis losses. Below 400 K, three magnetic phase transitions take place around 380 K, 320 K and 42 K. Detailed high resolution synchrotron and neutron powder diffraction (10-400 K) confirmed the magnetic transitions and phases as follows: TN intra ∼ 380 K denotes the transition from paramagnetism to intralayer antiferromagnetism (AFl), TN inter ∼ 320 K represents the transition from the AFl structure to the canted antiferromagnetic spin structure (AFmc), while TC ∼ 42 K denotes the first order magnetic transition from AFmc to canted ferromagnetism (Fmc + F(Nd)) due to ordering of the Mn and Nd sub-lattices. The maximum values of the magnetic entropy change and the adiabatic temperature change, around TC for a field change of 5 T are evaluated to be −ΔSM max ∼ 15.9 J kg−1 K−1 and ΔTad max ∼ 5 K, respectively. The first order magnetic transition associated with the low levels of hysteresis losses (therma

Expression of a Constitutively Active Nitrate Reductase Variant in Tobacco Reduces Tobacco-Specific Nitrosamine Accumulation in Cured Leaves and Cigarette Smoke

Burley tobaccos (Nicotiana tabacum) display a nitrogen-use-deficiency phenotype that is associated with the accumulation of high levels of nitrate within the leaf, a trait correlated with production of a class of compounds referred to as tobacco-specific nitrosamines (TSNAs). Two TSNA species, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N-nitrosonornicotine (NNN), have been shown to be strong carcinogens in numerous animal studies. We investigated the potential of molecular genetic strategies to lower nitrate levels in burley tobaccos by overexpressing genes encoding key enzymes of the nitrogen-assimilation pathway. Of the various constructs tested, only the expression of a constitutively active nitrate reductase (NR) dramatically decreased free nitrate levels in the leaves. Field-grown tobacco plants expressing this NR variant exhibited greatly reduced levels of TSNAs in both cured leaves and mainstream smoke of cigarettes made from these materials. Decreasing leaf nitrate levels via expression of a constitutively active NR enzyme represents an exceptionally promising means for reducing the production of NNN and NNK, two of the most well-documented animal carcinogens found in tobacco products

Preferred Features of E-Mental Health Programs for Prevention of Major Depression in Male Workers: Results From a Canadian National Survey

Background: Major depression is a prevalent mental disorder and imposes considerable burden on health and productivity. Men are not immune to major depression, yet they often delay seeking help because of perceived stigma and gender norms. E-mental health programs hold potential for early prevention of major depression. However, we have little knowledge about men\u27s preferences for design features of e-mental health programs. Objectives: The objective of this study was to (1) estimate and compare the proportions of Internet use for medical information, preferred design features, and likely use of e-mental health programs; (2) examine factors associated with the likely use of e-mental health programs; and (3) understand potential barriers to the use of e-mental health programs among Canadian working men, who were at high risk of a major depressive episode (MDE). Methods: A cross-sectional survey in 10 Canadian provinces was conducted between March and December 2015. Random digit dialing method was used through household landlines and cell phones to collect data from 511 working men who were at high risk of having an MDE and 330 working men who were at low risk of having an MDE. Results: High-risk men were more likely to endorse the importance of accessing health resources on the Internet than low-risk men (83.4% vs 75.0%, respectively; P=.01). Of the 17 different features assessed, the top three features most likely to be used by high-risk men were: information about improving sleep hygiene (61.3%), practice and exercise to help reduce symptoms of stress and depression (59.5%), and having access to quality information and resources about work stress issues (57.8%). Compared with men at low risk for MDE, men at high risk for MDE were much more likely to consider using almost every one of the different design features. Differences in preferences for the design features by age among men at high risk of MDE were found only for 3 of 17 features. Differences in preferences for design features between English- and French-speaking participants were found only for 4 out of the 17 features. Analysis of qualitative data revealed that privacy issues, perceived stigma, ease of navigation, personal relevance, and lack of personal interaction, time, and knowledge were identified as barriers to the use of e-mental health programs in working men who were at high risk of MDE. Conclusion: E-mental health programs may be a promising strategy for prevention of depression in working men. Development of e-mental health programs should consider men\u27s preferences and perceived barriers to enhance the acceptability of this approach

A comparative study of magnetic behaviors in TbNi2, TbMn2 and TbNi2Mn

All TbNi2, TbMn2, and TbNi2Mn compounds exhibit the cubic Laves phase with AB2-type structure in spite of the fact that the ratio of the Tb to transition-metal components in TbNi2Mn is 1:3. Rietveld refinement indicates that in TbNi2Mn the Mn atoms are distributed on both the A (8a) and B (16d) sites. The values of the lattice constants were measured to be a = 14.348 Å (space group F-43 m), 7.618 Å, and 7.158 Å (space group Fd-3 m) for TbNi2, TbMn2, and TbNi2Mn, respectively. The magnetic transition temperatures TC were found to be TC = 38 K and TC = 148 K for TbNi2 and TbNi2Mn, respectively, while two magnetic phase transitions are detected for TbMn2 at T1 = 20 K and T2 = 49 K. Clear magnetic history effects in a low magnetic field are observed in TbMn2 and TbNi2Mn. The magnetic entropy changes have been obtained

Molecular Engineering of Potent Sensitizers for Very Efficient Light Harvesting in Thin-Film Solid-State Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have shown significant potential for indoor arid building integrated photovoltaic applications. Herein we present three new D-A-pi-A organic sensitizers, XY1, XY2, and XY3, that exhibit high molar extinction coefficients and a broad absorption range. Molecular modifications of these dyes, featuring a benzothiadiazole (BTZ) auxiliary acceptor, were achieved by introducing a thiophene heterocycle as well as by shifting the, position of BTZ on the conjugated bridge. The ensuing high molar absorption coefficients enabled the fabrication of highly efficient thin-film solid-state DSSCs with only 1.3 mu m mesoporous TiO2 layer. XY2 with a molar extinction coefficient of 6.66 X 10(4) M-1 cm(-1) at 578 nm led to the best photovoltaic performance of 7.51%

Magnetocaloric effect in the metamagnet ErRhSi compound

The magnetocaloric effect is observed in the 1:1:1 compound ErRhSi, which is a metamagnet is reported in this paper. ErRhSi crystallizes in the orthorhombic space group Pnma, adopting the TiNiSi structure type, with lattice parameters a(Å) = 6.7903(5), b(Å) = 4.1881(3), and c(Å) = 7.3847(4). Our magnetic measurements confirm an antiferromagnetic phase transition at TN ≈ 8.5 K, also supported by the specific heat measurement. Crystal field effects of Er3+ are suggested by the inverse magnetic susceptibility data which do not conform to an ideal Curie-Weiss behaviour and also by the total entropy that attains Rln (2) at TN. Although the magnetic hysteresis indicates ErRhSi to be a soft magnet, several clear metamagnetic features are observed at 2 K. Magnetic entropy change ΔSM = − 8.7 J/kg-K is observed at about 9 K with the application of 5 T magnetic field. The corresponding adiabatic temperature change ΔTad is about 4 K. Large magnetocaloric effects suggest that this material is suitable for the low temperature magnetic refrigeration