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REDD+ is one of the climate change mitigation options in the forestry sector in developing countries, which is under different phases of implementation. India is under the readiness phase of REDD+ implementation, and has developed National REDD+ Strategy and Forest Reference Level. Relevant policies, laws and regulations related to forest resources support the implementation of REDD+ activities. Lack of capacity of the stakeholders on REDD+ related issue, as well as lack of availability of adequate quality planting stocks, and readily available international and national finance are identified as the challenges for implementation of REDD+ activities in India. [ABSTRACT FROM AUTHOR]

This paper investigates the ferromagnetism in ZnO:Mn powders and presents our findings about the role played by the doping concentration and the structural defects towards the ferromagnetic signal. The narrow-size-distributed ZnO:Mn nanoparticles based powders with oxygen rich stoichiometery were synthesized by wet chemical method using zinc acetate dihydrate and manganese acetate tetrahydrate as precursors. A consistent increase in the lattice cell volume, estimated from x-ray diffraction spectra and the presence of Mn 2p3/2 peak at ∼640.9 eV, in x-ray photoelectron spectroscopic spectra, confirmed a successful incorporation of manganese in its Mn2+ oxidation state in ZnO host matrix. Extended deep level emission spectra in Mn doped ZnO powders exhibited the signatures of oxygen interstitials and zinc vacancies except for the sample with 5 at. % Mn doping. The nanocrystalline powders with 2 and 5 at. % Mn doping concentration were ferromagnetic at room temperature while the 10 at. % Mn doped sample exhibited paramagnetic behavior. The maximum saturation magnetization of 0.05 emu/g in the nanocrystalline powder with 5 at. % Mn doping having minimum defects validated the ferromagnetic signal to be due to strong p-d hybridization of Mn ions. [ABSTRACT FROM AUTHOR]

This paper reports the temperature-dependent tailoring of acceptor defects in oxygen rich ZnO thin films, for enhanced p-type conductivity. The oxygen rich p-type ZnO thin films were successfully grown by pulsed laser deposition on silicon substrate at different postdeposition annealing temperatures (500-800 °C). The oxygen rich ZnO powder was synthesized by wet chemical method using zinc acetate dihydrate [Zn(CH3COO)2·2H2O] and potassium hydroxide (KOH) as precursors. The powder was then compressed and sintered to make pellets for pulsed laser deposition system. The x-ray diffraction analysis exhibits an improved crystallinity in thin films annealed at elevated temperatures with a temperature-dependent variation in lattice constants. An analysis of Auger Zn L3M4,5M4,5 peak reveals a consistent decrease in interstitial zinc (Zni) exhibiting its temperature-dependent reversion to zinc lattice sites. Room temperature photoluminescence of the p-type ZnO shows a dominant deep level emission peak at ∼3.12 eV related to oxygen interstitials (acceptors). The relative concentration of oxygen interstitials (Oi) increases with increase in annealing temperature, resulting in enhanced hole carrier concentration. The maximum hole carrier concentration of 6.8 × 1014 cm-3 (indicating p-type conductivity) was estimated using Hall probe measurements for the thin film sample annealed at 700 °C. [ABSTRACT FROM AUTHOR]

The Lee model code is used to compute neon soft x-ray yield Ysxr for the NX2 plasma focus as a function of pressure. Comparison with measured Ysxr shows reasonable agreement in the Ysxr versus pressure curve, the absolute maximum yield as well as the optimum pressure. This gives confidence that the code gives a good representation of the neon plasma focus in terms of gross properties including speeds and trajectories and soft x-ray yields, despite its lack of modeling localized regions of higher densities and temperatures. Computed current curves versus pressure are presented and discussed particularly in terms of the dynamic resistance of the axial phase. Computed gross properties of the plasma focus including peak discharge current Ipeak, pinch current Ipinch, minimum pinch radius rmin, plasma density at the middle duration of pinch npinch, and plasma temperature at middle duration of pinch Tpinch are presented and the trends in variation of these are discussed to explain the peaking of Ysxr at optimum pressure. [ABSTRACT FROM AUTHOR]

The effect of energetic argon ion irradiation, using a 3.3 kJ pulsed plasma focus device, is studied systematically on a 4H polytype (002)-oriented CdI2 stoichiometric film having compressive residual stress. The CdI2 films were exposed to energetic ions from the plasma focus device at different distances from the top of the central electrode. The irradiation was found to change the orientation of the film to (110) at certain moderate irradiation distances. A linear decrease in grain size and residual stress was observed with decreasing irradiation distance (or increasing ion energy), consistent with both structural and morphological observations. The direct optical energy gap Eg was found to increase linearly at the rate 15 μeV/atm with the compressive stress. The combined data of present compressive stress and from earlier reported tensile stress show a consistent trend of Eg change with stress. The iodine–iodine distance in the unit cell could be responsible for the observed change in Eg with stress. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We demonstrate interface energy level engineering, exploiting the modification in energy band structure across Verwey transition temperature (TV) of Fe3O4, in a Fe3O4(111)/Alq3/Co spin-valve (SV). I-V characteristics exhibit a transition in conduction mode from carrier injection to tunneling across TV of Fe3O4 electrode. Both giant magneto-resistance (GMR) and tunneling MR (TMR) have been observed in a single SV, below and above TV, respectively. We have achieved room-temperature SV operation in our device. We believe that the tuning of charge gap at Fermi level across TV resulting in a corresponding tuning of conduction mode and a unique cross over from GMR to TMR. [ABSTRACT FROM AUTHOR]

We show a large negative magnetoresistance (MR) of ≈10% near room temperature in FeRh0.46Pd0.54, which increases to more than 60% at low temperatures. The magnitude of resistivity and, hence, MR depend on the history of the sample in HT (magnetic field-temperature) space, e.g., resistivity at 5 K changes by more than 70% with thermal cycling. These results are explained due to slow kinetics of the transformation from austenite antiferromagnetic (AF) to martensite ferromagnetic (FM) state with the decrease in temperature. As a result, AF to FM transformation remains incomplete on experimental time scales and non-ergodic AF phase co-exists with a low temperature equilibrium FM phase. In the present system, the kinetics of the transition is shown to dominate up to 150 K, which is significantly high in comparison to other kinetically arrested systems. [ABSTRACT FROM AUTHOR]

The hydrogenated amorphous carbon nitride (a-CNx:H) thin films were synthesized on the SS-304 substrates using a dense plasma focus device. The a-CNx:H thin films were synthesized using CH4/N2 admixture gas and 20 focus deposition shots on substrates placed at different distances from the anode top. X-ray photoelectron spectroscopy and Raman analysis confirmed different C-N bonding in the a-CNx:H thin films. A decrease in the N/C ratio as well as the sp3/sp2 ratio with an increase in the substrate distance has been observed. The higher amount of C-N formation for the film synthesized at 10 cm is observed which decreases with increasing distance. The X-ray photoelectron spectroscopy and Raman analysis affirmed the C ≡ N presence in all the thin films synthesized at different distances. The morphology of the synthesized a-CNx:H thin films showed nanoparticles and nanoparticle clusters formation at the surface. The hardness results showed comparatively lower hardness of the a-CNx:H thin films due to the presence of C ≡ N. The C-N formation with lower amount of C ≡ N and a higher N/C ratio as well as a higher sp3/sp2 ratio for the films synthesized at 10 cm show reasonably higher hardness. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Our systematic path dependent resistivity study in H – T space shows that paramagnetic (PM)–ferromagnetic (FM) transition in CoS 1.76 Se 0.24 is kinetically arrested. The resistivity at low temperature depends on the path followed in H – T space and the critical field required for PM to FM transition varies non-monotonically with temperature. Measurements under CHUF (cooling and heating in unequal magnetic field) protocol show reentrant transition on warming under higher magnetic field (than that applied during cooling), which indicate that PM state is the non-equilibrium state. Among the growing list of diverse system showing glass like arrested magnetic states, the present system is the first example where, kinetic arrest is observed for a disordered (here PM) to ordered (here FM) magnetic transition. [ABSTRACT FROM AUTHOR]

Unconventional thermal effects across the first-order antiferromagnetic (AFM)-ferromagnetic (FM) transition in an intermetallic alloy are reported. They show instances of warming when heat is extracted from the sample, and cooling when heat is provided to the sample across the AFM-FM transition in Ta-doped HfFe2, thus providing indisputable evidence of metastable supercooled AFM and superheated FM states, respectively. Such thermal effects are observed in a magnetic solid prepared from commercially available materials. The transition proceeds in multiple steps which is interpreted in the framework of quenched disorder broadening of the AFM-FM transition and classical nucleation theory. Measurements in the presence of a magnetic field conform to the above framework. [ABSTRACT FROM AUTHOR]

Schumann resonances (SRs) are the AC components of the global electric circuit and are excited by the lightning activity within the Earth-ionosphere waveguide. An induction magnetometer, which was operated from the Indian Antarctic station, Maitri (70.8°S, 11.7°E), served to examine the SR parameters, namely the amplitude and frequency, in the north-south (HNS) and east-west (HEW) magnetic components. The analysis for the first resonant mode presented in this work reveals a strong UT variation in its amplitude in seasonal as well as yearly timescales. The NS amplitude reveals a semi-diurnal variation with peaks at ~1000 and ~2100 UT, whereas the EW amplitude exhibits a strong diurnal variation with a pronounced peak at 1600 UT. The diurnal curves for the frequency for both components are similar in nature to those for the amplitude, but for a time shift. The diurnal trend in the amplitude is retained irrespective of seasons, whereas significant difference are noticed in the frequency behaviour between the summer and winter seasons, especially in the EW component. The observed diurnal variation in the SR intensity is explained in terms of the dominant thunderstorm activity centred over the three convectively active regions: Asia/ Maritime Continent (Indonesia), South America and Africa. The diurnal variation in frequency depends not only on the location of the thunderstorm region with respect to the observer, but also on the ionospheric day/night conditions and the Earth-ionosphere cavity thickness. [ABSTRACT FROM AUTHOR]

Large magnetocaloric effect (MCE) and magnetoresistance (MR) together with negligible hysteresis loss have been observed in ErNiSi compound, which undergoes metamagnetic transition at low temperatures. Magnetization, heat capacity, and resistivity measurements confirm the metamagnetic transition. Both MCE and MR follow H² dependence in the paramagnetic regime. The maximum value of isothermal entropy change (ΔSM) and MR for a field change of 50 kOe are found to be 19.1 J/kg K and ~34%, respectively. Large MCE with negligible magnetic hysteresis loss could make this material promising for low temperature magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The Al/a-C nanocomposite thin films are synthesized on Si substrates using a dense plasma focus device with aluminum fitted anode and operating with CH4/Ar admixture. X-ray diffractometer results confirm the formation of metallic crystalline Al phases using different numbers of focus shots. Raman analyses show the formation of D and G peaks for all thin film samples, confirming the presence of a-C in the nanocomposite thin films. The formation of Al/a-C nanocomposite thin films is further confirmed using X-ray photoelectron spectroscopy analysis. The scanning electron microscope results show that the deposited thin films consist of nanoparticles and their agglomerates. The sizes of th agglomerates increase with increasing numbers of focus deposition shots. The nanoindentation results show the variations in hardness and elastic modulus values of nanocomposite thin film with increasing the number of focus shots. Maximum values of hardness and elastic modulus of the composite thin film prepared using 20 focus shots are found to be about 10.7 GPa and 189.2 GPa, respectively. [ABSTRACT FROM AUTHOR]

Nanostructured multiphase zirconia films (MZFs) are deposited on Zr substrate by the irradiation of energetic oxygen ions emanated from a plasma focus device. The oxygen operating gas pressure of 1 mbar (1 bar = 105 Pa) provides the most appropriate ion energy flux to deposit crystalline ZrO2 films. X-ray diffraction (XRD) patterns reveal the formation of polycrystalline ZrO2 films. The crystallite size (CS), crystal growth, and dislocation densities are attributed to increasing focus shots, sample axial distances, and working gas pressures. Phase and orientation transformations from t-ZrO2 to m-ZrO2 and c-ZrO2 are associated with increasing focus shots and continuous annealing. For lower (200 °C) annealing temperature (AT), full width at half maximum (FWHM) of diffraction peak, CS, and dislocation density (δ) for (020) plane are found to be 0.494, 16.6 nm, and 3.63 × 10−3 nm−2 while for higher (400 °C) AT, these parameters for (111) plane are found to be 0.388, 20.87 nm, and 2.29 × 10−3 nm−2, respectively. Scanning electron microscope (SEM) results demonstrate the formation of rounded grains with uniform distribution. The estimated values of atomic ratio (O/Zr) in ZrO2 films deposited for different axial distances (6 cm, 9 cm, and 12 cm) are found to be 2.1, 2.2, and 2.3, respectively. Fourier transform infrared (FTIR) analysis reveals that the bands appearing at 441 cm−1 and 480 cm−1 belong to m-ZrO2 and t-ZrO2 phases, respectively. Maximum microhardness (8.65±0.45 GPa) of ZrO2 film is ∼ 6.7 times higher than the microhardness of virgin Zr. [ABSTRACT FROM AUTHOR]

This paper reports the tailoring of acceptor defects in oxygen rich thin films at different post-deposition annealing temperatures (500-800°C) and doping concentrations. The XRD spectra exhibited the nanocrystalline nature of thin films along with inconsistent variation in lattice parameters suggesting the temperature-dependent activation of structural defects. Photoluminescence emission spectra revealed the temperature dependent variation in deep level emissions (DLE) with the presence of acceptors as dominating defects. The concentration of native defects was estimated to be increased with temperature while a reverse trend was observed for those with increasing doping concentration. A consistent decrease in DLE spectra, with increasing content, revealed the quenching of structural defects in the optical band gap of favorable for good quality thin films with enhanced optical transparency. [ABSTRACT FROM AUTHOR]

We have achieved giant enhancement of magnetoresistance (MR) by the formation of La0.67Sr0.33MnO3 (LSMO)-Pr0.67Ca0.33MnO3 (PCMO) core-shell nanostructure. Astonishingly, 1143% enhancement of MR in the core-shell nanostructure has been observed with respect to the parent PCMO nanoparticles at 100 K and 2 T magnetic field. The observed giant enhancement is the result of significantly weaken the charge ordered state in the created ferromagnetic-charge ordered core-shell nano structure. Our study clearly indicates a method to achieve huge enhancement of magnetoresistance that can eventually give rise artificially created superior materials important for magnetic field sensor technology. [ABSTRACT FROM AUTHOR]

(ZnO) 1−x(Co 3O 4) x≤0.05 thin-film series were deposited in vacuum Ar–O 2 and N 2 environment using the pulsed-laser deposition (PLD) technique. Bulk pellets were prepared by the solid-state reaction technique by mixing ZnO and Co 3O 4 powder and further utilized for deposition of thin films. XRD patterns of pellets exhibit homogeneous ZnCoO phase formation with no other impurity phases. Single-phase (002) oriented ZnCoO thin films were formed without any cobalt segregation. The cobalt core peaks confirmed the existence of +2 valence state of cobalt in thin-film samples, and the binding energy difference between the cores peaks showed the homogeneous doping of cobalt in ZnO matrix. The magnetic ordering was achieved in thin films samples which were deposited in vacuum and N 2 ambience. [ABSTRACT FROM AUTHOR]

Low-temperature (< 10 eV) plasmas with densities varying over a very wide range from 10^13\ \m^-3 at the lower end to as high as 10^23\ \m^-3 have firmly established themselves as one of the most efficient and versatile tools to create and process materials at nanoscale. The dense plasma focus (DPF) device, which is a noncylindrical Z-pinch facility that compresses the plasma to very high energy densities, offers a complex mix of high energy ions of the filling gas species, immensely hot and dense decaying plasma, fast-moving ionization wave front, and a strong shockwave that provides a unique plasma and a physical/chemical environment that is completely unheard of in any other conventional plasma-based deposition or processing facility. This review aims to highlight the novel features offered by pulsed high-energy-density pinch plasmas from a DPF, having temperatures and densities a few orders of magnitudes higher than conventional low-temperature plasmas, in the processing and the synthesis of materials at nanoscale. The nanoscale fabrication using the DPF device is elaborated and discussed in two broad categories: 1) top–down nanoscale fabrication by processing of bulk or thin-film target materials that are placed downstream the anode axis by the energetic transient flux of energetic ions, the hot decaying plasma, the fast ionization wave front, and the shock front; and 2) bottom–up nanoscale fabrication by deposition of nanostructured thin films of metals and/or their nitrides, carbides, and oxides by ablating the metal fitted on to the anode top under suitable reactive or inert background plasma. [ABSTRACT FROM PUBLISHER]

First-order antiferromagnetic insulating (AFI)-ferromagnetic metallic (FMM) transition as a function of temperature and magnetic field has been imaged using magnetic force microscopy (MFM) in La5/8-yPryCa3/8MnO3 (y = 0.45) thin film grown on NdGaO3 substrate. These images, showing AFI to FMM transformation during in-field cooling and reverse transformation during warming of the same region, cannot be described solely in terms of the broad first-order transition due to quench disorder. Growth morphology of the FMM phase is observed to be path dependent as larger size FMM regions (but with smaller net fraction) are observed for isothermal field induced transition when compared to isofield thermal transition. This is shown to be a consequence of the glasslike arrested AFI state even at ≈100 K. Apparent variable range hopping like transport near TMi during cooling is shown to be a consequence of growth of the FMM phase in an AFI matrix. [ABSTRACT FROM AUTHOR]

Objective: Although undernutrition is recognized as a risk factor for mortality among people living with HIV (PLWHIV), even among those initiating antiretroviral therapy, few studies have explored the underlying determinants of undernutrition. The objectives of the present study were to: (i) examine the independent association between household food security, individual diet quality and nutritional status; and (ii) determine if any association between food security and nutritional status is mediated through diet quality.Design: Cross-sectional baseline survey.Setting: Gulu and Soroti districts, Uganda.Subjects: Nine hundred and two PLWHIV recruited into a study evaluating the impact of a food assistance programme supported by the World Food Programme.Results: Food security and diet quality were measured using the Household Food Insecurity Access Scale (HFIAS) and the Individual Dietary Diversity Score (IDDS), respectively. Multivariate regression results demonstrated that HFIAS and IDDS independently predict BMI (P < 0.01) and mid upper-arm circumference (P < 0.05). The adjusted odds ratio of being underweight (BMI < 18.5 kg/m2) among individuals living in severely food-insecure households was 1.92 (P < 0.0 0 1); individuals consuming a highly diverse diet had an adjusted odds ratio of being underweight of 0.56 (P < 0.05) compared with those consuming a diet of low diversity. Similar results were observed when mid upper-arm circumference and wasting were modelled as outcomes. Using path analysis, we observed that the indirect effect of food insecurity on BMI mediated through dietary diversity is negligible, and mostly a result of the direct effect of food insecurity on BMI.Conclusions: Our results provide an empirical basis for focused efforts on improving food access and diet quality among PLWHIV. Addressing the broader structural determinants of food security of people infected and affected by HIV is crucial. [ABSTRACT FROM AUTHOR]

The present study is focused on the copper-doped ZnO system. Bulk copper-doped ZnO pellets were synthesized by a solid-state reaction technique and used as target material in pulsed laser deposition. Thin films were grown for different Cu doped pellets on sapphire substrates in vacuum (5×10 mbar). Thin films having (002) plane of ZnO showed different oxidation states of dopants. M- H curves exhibited weak ferromagnetic signal for 1-3 % Cu doping but for 5 % Cu doped thin film sample showed the diamagnetic behavior. For deeper information, thin films were grown for 5 % Cu doped ZnO bulk pellet in different oxygen ambient pressures and analyzed. PL measurement at low temperature showed the emission peak in thin films samples due to acceptor-related transitions. XPS results show that copper exists in Cu and Cu valence states in thin films and with increasing O ambient pressure the valence-band maximum in films shifts towards higher binding energy. Furthermore, in lower oxygen ambient pressure (1×10 mbar) thin films showed magnetic behavior but this vanished for the film grown at higher ambient pressures of oxygen (6×10 mbar), which hints towards the decrease in donor defects. [ABSTRACT FROM AUTHOR]

Spin valves have revolutionized the field of magnetic recording and memory devices. Spin valves are generally realized in thin film heterostructures, where two ferromagnetic (FM) layers are separated by a nonmagnetic conducting layer. Here, we demonstrate spin-valve-like magnetoresistance at room temperature in a bulk ferrimagnetic material that exhibits a magnetic shape memory effect. The origin of this unexpected behavior in Mn2NiGa has been investigated by neutron diffraction, magnetization, and ab initio theoretical calculations. The refinement of the neutron diffraction pattern shows the presence of antisite disorder where about 13% of the Ga sites are occupied by Mn atoms. On the basis of the magnetic structure obtained from neutron diffraction and theoretical calculations, we establish that these antisite defects cause the formation of FM nanoclusters with parallel alignment of Mn spin moments in a Mn2NiGa bulk lattice that has antiparallel Mn spin moments. The direction of the Mn moments in the soft FM cluster reverses with the external magnetic field. This causes a rotation or tilt in the antiparallel Mn moments at the cluster-lattice interface resulting in the observed asymmetry in magnetoresistance. [ABSTRACT FROM AUTHOR]

Abstract: The origin of anomalous thermomagnetic irreversibility in rare earth germanide has been addressed. Open hysteresis observed in magnetoresistance (MR) at low temperature is shown to decrease with increasing temperature which correlates with the corresponding isothermal magnetostriction (MS) measurements. These thermomagnetic irreversibilities are interpreted in terms of kinetic arrest of magnetic field induced first order transition. The minor loop study of isothermal MS suggests that open loop in MS and MR is associated with large magnetostriction across metamagnetic transitions. The magnetoresistance associated with the second metamagnetic transition at higher field is reversible where magnetostriction variation with field is negligible. [Copyright &y& Elsevier]

Data from the 2005 Ethiopia Demographic and Health Survey (EDHS) and the 2007 Zambia Demographic Health Survey (ZDHS) were analyzed to examine the association between World Health Organization (WHO) recommended IYCF indicators and nutritional status among children 0-23 months of age in Ethiopia and Zambia. A total of 1810 and 2512 children within this age group from Ethiopia and Zambia, respectively, were included in the analysis. Exclusive breast-feeding among children 0-5.9 months of age is low in both Ethiopia (43 %) and Zambia (51 %). Timely introduction of complementary food is lower in Ethiopia (61 %) compared to Zambia (90 %). Only 7 percent of children between 6-23 months of age consumed diets that met the minimum dietary diversity requirement of four or more food groups consumed per day compared to 37 % in Zambia. Multiple linear and logistic regression analyses using appropriate measures to account for the complex survey design were applied to examine the associations between IYCF practices and child anthropometry. Linear regression results show that exclusive breast-feeding (EBF) is positively associated with weight-for-height z-score (WHZ) (effect size (ES) 0.65; p<0.001) and weight-for-age z-score (WAZ) (ES 0.28; p<0.01) in Zambia. In Ethiopia, EBF under 6 months of age is negatively associated with height-for-age z-score (HAZ) (ES 0.81; p<0.01). Timely introduction of complementary food between 6-8 months of age was positively associated with HAZ (ES 1.19; p<0.01) in Zambia. Higher dietary diversity score was associated with higher HAZ (ES 0.23, p<0.001 in Ethiopia; ES 0.12, p<0.01 in Zambia) and WAZ (ES 0.17, p<0.001 in Ethiopia; ES 0.04, p<0.10 in Zambia) in both countries. The findings demonstrate the need to reinforce age- appropriate IYCF practices to address child undernutrition. Special attention is needed to improve the complementary feeding practices, particularly diet diversity for children 6-23 months of age, while sustaining a focus on EBF among children under 6 months of age, in order to improve overall nutritional status of young children in Ethiopia and Zambia. [ABSTRACT FROM AUTHOR]

The effects of Mn substitution on the physical properties and structural characteristics of BiPbSrCaCuMnO y (Bi-2223) superconductor system have been studied. For this, the samples of nominal composition BiPbSrCaCuMnO y ( x=0.00, 0.10, 0.15 & 0.20) was prepared by the solid-state reaction method. It has been found that the effects of Mn substitution favor the formation of Bi-2223 phases. The phase identification/gross structural characteristics of synthesized (HTSC) materials explored through powder X-ray diffractometer reveals that all the samples crystallize in orthorhombic structure with lattice parameters ( a=5.4918 Å, b=5.4071 Å, and c=37.0608 Å) up to Mn concentration of x=0.20. The critical transition temperature ( T) measured by standard four probe method has been found to depress from 108 K to 70 K and transport current density ( J) has been increased from 4.67×10 to 3.52×10 A cm as Mn content ( x) increases from 0.00 to 0.20. The surface morphology investigated through scanning electron microscope and atomic force microscopy (SEM and AFM) results that voids and grains size increases as the Mn concentration increases besides the nanosphere like structures on the surface of the Mn doped Bi-2223 sample. [ABSTRACT FROM AUTHOR]

Abstract: Tremendous amount of solar energy is hurled into the space by transient sporadic emissions occurring within the Sun. A fraction of this energy is transferred into the Earth''s magnetosphere by the magnetic reconnection process. Interplanetary magnetic field plays a crucial role in the excitation of geomagnetic storms and their subsequent evolution. The present study attempts to determine the influence of post-shock duration of southward B z on the development and intensification of intense () geomagnetic storms. The study presents 18 big storm events that occurred during the solar cycle 23. In all the cases under study, the interplanetary shocks were driven by the interplanetary coronal mass ejections (ICMEs). The ICME structures may contain southward magnetic fields within the sheath, the magnetic cloud or both in succession, which can lead to the development of intense geomagnetic storms. In addition, dependence of storm strength on the total energy influx into the magnetosphere () and ring current (E RC ) energy is also assessed. Geomagnetic storm characteristics are examined at a low-latitude station, Alibag (geographic lat. , long. ; geomagnetic lat. , long. ), using high resolution digital data. The minimum duration of southward B z for strengthening the storms is . All intense storms are found to have minimum values of southward directed B z to be and interplanetary electric field . Intensity of geomagnetic storms at low-latitudes follows a fairly linear dependence on the ring current energy. [Copyright &y& Elsevier]

Study of expansion dynamics of pulsed-laser ablation plasmas from Fe and graphite targets is presented. A 532 nm Q-switched Nd:YAG laser with fluence of 30 J cm is used to ablate the Fe and graphite targets in various Ar ambient gas pressures. Plasma ablation parameters for the two target materials are estimated using snow-plow and shock-wave models, which show that the laser beam energy deposited to ablated species remains at 70% for both targets at all ambient pressures. The plume splitting was observed, more prominently, for Fe plasma as it moves faster compared to graphite plasma. The difference in plasma plume fronts' speeds for different targets was attributed to the significant difference in mass of the ablated plasma for two targets, as estimated from simulation results. [ABSTRACT FROM AUTHOR]

The magnetic nanoparticles of Fe/FeCo/FePt, in the past, in a PLD system were grown by us using argon ambient gas pressure of about 0.1-75.0 mbar, as the ambient gas pressure can be used to tune the energy of the incident plasma plume species, the expansion volume, the growth duration, etc. which can control the particle size. In present paper, we report the direct synthesis of small-sized nanoparticles even when no ambient gas was used, with the experiments being done in higher vacuum of about 10 mbar in PLD chamber. The deposition rate under vacuum condition is significantly higher than the deposition rate at high ambient pressure. The study of inplane and outplane magnetic properties, along with XRD results, confirmed that the as-deposited CoPt nanoparticles thin film has oriented growth. The as-deposited CoPt nanoparticles are in magnetically soft fcc phase and a post deposition annealing at 600°C resulted in phase transition to magnetically hard fct phase. [ABSTRACT FROM AUTHOR]

Pulsed laser generated Fe plasma plumes have been studied near the target surface using time-resolved imaging. A fast gated intensified CCD camera is used to capture the images with a gate width of 2 ns. The plasma plumes were generated using a Q-switched Nd-YAG laser at 1064 nm with a fluence of ∼2 kJ/cm. The expansion studies were done up to a distance of about 5 mm from the target surface. The snow plow and the shock wave models were fitted to the experimental data to estimate the ablation parameters and to study plasma expansion dynamics (i.e. velocity and kinetic temperature) at Ar ambient gas pressure of 1 mbar. The high magnification near-target imaging results showed that the axial plume expansion velocity is about ∼10 ms. A strong shock is also captured near the target at few tens of nano-seconds, which was not observable with moderate magnification. [ABSTRACT FROM AUTHOR]

In the paper, we report the synthesis and characterization of bulk and thin films of cobalt doped ZnO. Doped ZnO thin films with (002) orientation were grown on sapphire substrates in different N pressures using a Nd:YAG laser based PLD system. XPS analysis of thin films confirmed the presence of Co ions in the bulk target material and in thin film samples. PL measurements exhibited emission in the visible region only. M- H curves showed ferromagnetic nature of thin films which was found to change with the change in ambient nitrogen gas pressure. The surface morphology of thin films was also affected by ambient nitrogen gas pressure. [ABSTRACT FROM AUTHOR]

A time resolved imaging study of pulsed laser ablated Fe and Al plasma plumes with specific interest in the splitting of plumes into the slow and fast moving components as they expand through the background argon gas at different pressures is reported. The material ablation was achieved using a Q-switched Nd:YAG (yttrium aluminum garnet) laser operating at 532 nm with a pulse duration of ∼8 ns full width at half maximum and a fluence of 30 Jcm-2 at the target surface. Typical time resolved images with low magnification show that the splitting occurs at moderate background gas pressures (0.5 and 1.0 mbar for Fe, and 0.2 mbar for Al plasma plumes). The plume splitting did not occur for higher background gas pressures. [ABSTRACT FROM AUTHOR]

A table top ~0.2-kJ miniature plasma focus (PF) device "FMPF-1" (2.4 µF, 27 ± 2 nH, T/4 ~400 ns, 9-14 kV) has been successfully used as a compact and portable, pulsed hard X-ray (HXR) source for fast (< 32-ns exposure time) radiography applications using Hydrogen (H2) as filling gas. The overall dimensions of the apparatus, which includes capacitor bank, sparkgap switch, and the focus chamber, are 0.2 m x 0.2 m x 0.5 m, and the system weighs about 25 kg. The time resolved information of HXR emission and their relative yield along the axial (0°) and radial (90°) directions are measured using a pair of cross-calibrated scintillator-photomultiplier detectors. The average pulse durations (full-width at half-maximum) of HXR pulse are measured to be 29±3 ns in axial direction and 18±2 ns in the radial direction. The average axial to radial HXR yield anisotropy is found to be 3.9 ± 0.9 at the optimum pressure of 3.5 mbar. The experimental estimation of the effective average energy of the HXR emission, with high-Z (Pb) insert in stainless steel anode is found to be in the range of 60-80 keV. The potential of the miniature PF as compact radiographic source is illustrated by radiographic imaging, with submillimeter range (< 0.3 mm) spatial resolution, of different objects placed outside the chamber. [ABSTRACT FROM AUTHOR]

The effects of the different number (1, 2 and 3) of H+ ion irradiation shots on pulsed laser deposited FePt thin films, using pulsed plasma focus device, are investigated. The FePt thin films were exposed to energetic H+ ions in a plasma focus device at a fixed distance of 4 cm from the top of central electrode. It was deduced that single shot ion irradiation based transient thermal treatment induces an effect similar to the conventional annealing at 400°C. Well-separated nanoparticles are formed, and the significant enhancement of the coercivity, by about two orders of magnitude, at a lower annealing temperature of 400°C has been observed in the single shot ion irradiated samples. The increase of plasma focus ion irradiation shots lead to the amorphorization in irradiated FePt samples due to excessive energy transfer causing more defects and lattice distortion, and a decreasing coercivity trend in irradiated and annealed samples are observed due to reduction in the texture coefficient of magnetic easy axis (001) orientation fct phase. [ABSTRACT FROM AUTHOR]

Objectives: The relationship between Fe status and HIV infection is complex and poorly understood. While anaemia is a major complication of HIV infection, higher Fe stores may be associated with disease progression. There is limited and conflicting data available from Africa. Design: Cross-sectional and prospective cohort study. Setting, subjects and methods: We examined the association between postpartum Fe status (Hb, serum ferritin (SF) and transferrin receptor (TfR)) and viral load (VL) and HIV-related mortality in 643 HIV-positive Zimbabwean women over a period of 12 months. Results: In non-anaemic women a log10 increase in SF was associated with a 2·3-fold increase in VL (P=0·019); this association was absent in anaemic women. In prospective analyses, a log10 increase in SF was associated with a 4-fold increase in mortality by 12 months (P=0η002). Hb was negatively associated with VL (P=0·001) and mortality (P=0·047). The adverse associations between SF and both VL and mortality were found at SF concentrations >45 μg/l (P<0·05). Controlling for α1 acid glycoprotein, a marker of inflammation, attenuated the association between both SF and VL and mortality, but these remained significant. Conclusions: These results are consistent with the hypothesis that high Fe stores have adverse consequences in HIV infection. If adverse consequences are real, our data suggest that they occur at SF concentrations exceeding those consistent with adequate Fe nutriture. [ABSTRACT FROM AUTHOR]

Objectives:The acute phase response (APR) influences indicators of iron status. A recent WHO/CDC consultation recommended concurrent measurement of α-1-acid-glycoprotein (AGP) in surveys to control for the APR, and aid in interpreting iron status. They proposed further exploratory analyses using AGP. We examined whether the APR (measured by AGP) influences the expected relationships between iron status indicators in an HIV-infected population.Subjects:We measured hemoglobin (Hb), serum ferritin (SF), transferrin receptor (TfR), erythropoietin (EPO) and AGP in a cross-sectional survey of 643 HIV-positive Zimbabwean women.Results:SF was significantly higher in APR-positive (AGP>1 g/l) women (P<0.001), in whom there was no association between SF and Hb. TfR was inversely associated with Hb, in both APR-positive and APR-negative women (P<0.001). However, among anemic women (Hb<110 g/l), APR-positive women had marginally lower TfR concentrations (P=0.053). There was no difference in EPO response to decreasing Hb among APR-positive and APR-negative women.Conclusions:AGP captured the influence of the APR on iron indicators and their relationships with each other. The APR influenced SF and its relationship with Hb as expected. TfR behaved unexpectedly. Although TfR has been promoted as an iron indicator that is uninfluenced by the APR, TfR concentrations were depressed among anemic APR-positive women. Because TfR reflects iron deficiency and erythropoietic activity, pro-inflammatory cytokines associated with the APR may be inhibiting erythropoeisis, which is reflected by lower TfR concentrations. We support the WHO/CDC recommendation that AGP is a useful indicator to assess the influence of the APR on iron status indicators.European Journal of Clinical Nutrition (2009) 63, 787–793; doi:10.1038/ejcn.2008.33; published online 28 May 2008 [ABSTRACT FROM AUTHOR]

Abstract: The variations in the horizontal and declination components of the geomagnetic field in response to the interplanetary shocks driven by fast halo coronal mass ejections, fast solar wind streams from the coronal hole regions and the dynamic pressure pulses associated with these events are studied. Close association between the field-aligned current density (j ∥) and the fluctuations in the declination component (ΔD ABG) at Alibag is found for intense storm conditions. Increase in the dawn-dusk interplanetary electric field (E y ) and ΔD ABG are generally in phase. However, when the magnetospheric electric field is directed from dusk to dawn direction, a prominent scatter occurs between the two. It is suggested that low-latitude ground magnetic data may serve as a proxy for the interplanetary conditions in the solar wind. [Copyright &y& Elsevier]

The anisotropies of neutron and high energy deuteron emissions from the NX2 plasma focus device [M. V. Roshan et al., Phys. Lett. A 373, 851 (2009)] are studied. The nuclear activation of graphite targets is used to measure the fluences of high energy deuterons in the axial and radial directions. Two bismuth germanate scintillation detectors connected to multichannel analyzer systems are used for the detection of 511 keV gamma rays resulting from positron annihilation in the two targets. In addition, fast neutron activation detectors are employed to measure the axial and radial fluences of fusion neutrons. These detection systems are calibrated using the simulation code MCNPX [L. S. Waters et al., AIP Conf. Proc. 896, 81 (2007)]. Two distinct regimes of neutron and deuteron anisotropies are observed for the NX2 device. For deuterium gas pressures below 10 mbar, the neutron anisotropy increases with increasing pressure, while the overall neutron yield remains low. For gas pressures of 10–14 mbar, the neutron anisotropy is essentially constant, while, with increasing pressure, the neutron yield rises rapidly and the deuteron anisotropy falls. [ABSTRACT FROM AUTHOR]

Fe-doped polycrystalline samples La0.67Ca0.33Fe x Mn1 − x O3 ( x = 0%, 5%, 7.5%, 10% and 15%) are studied employing 57Fe Mössbauer effect measurements. The room temperature Mössbauer measurements of all the samples indicate the presence of Fe + 3 state and it is observed that the quadrupole splitting remains constant up to 10% Fe doping and increases with 15% Fe doping. Resistivity data shows increasing insulating behaviour with Fe doping and insulating region follows Efros–Shlovskii variable range hoping model. [ABSTRACT FROM AUTHOR]

Nanocrystalline multiphase titanium oxycarbide (TiCxOy) thin films composed of TiC2, TiO0.325, Ti2O3 and graphitic carbon have been deposited on titanium substrates, using energetic carbon ions delivered by the UNU/ICTP and the NX2 plasma focus devices operated at different repetition rates. X-ray diffraction (XRD) patterns of the nanocomposite films reveal the relative transformation of various oxide and carbide phases accompanied by the suppression of the TiC2 phase when the energy flux of the ion beam and the repetition rate are increased. A field emission scanning electron microscope (FESEM) with an energy dispersive X-ray spectroscopy (EDS) attachment reveals a non-porous microcrack-free nanocrystalline granular surface morphology of the composite films with uniform carbon distribution. X-ray photoelectron spectroscopy (XPS) confirms the formation of oxycarbides (TiCxOy) along with significant carbon adsorbate. Raman studies of the films also verify the relative phase transformation in the TiCxOy nanocomposite by tuning the deposition parameters. The Vickers microhardness of the sample surface is improved more than 400%. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic and transport properties of Ti substituted are drastically affected with a change in preparation conditions. Low temperature infra-red absorption measurements reveal that this is perhaps due to inhomogeniety in substitution of on Mn sites. It is found that, in the high temperature annealed samples, the substitution of Ti supresses the double exchange interaction due to the formation of –O– chains. While in the low temperature annealed case substitution of Ti causes formation of isolated ferromagnetic clusters linked to each other by a variable range hopping polaron. [Copyright &y& Elsevier]

Abstract: We report the effects of local structure on the electrical transport and magnetic properties of La0.67Ca0.33Mn1− x Ti x O3 (0⩽x⩽0.10) system. Linear increase in the lattice parameters, consequent expansion of unit cell and a monotonic decrease in the relative Mn4+ concentration with x suggest that Ti4+ predominantly replaces Mn4+ in La0.67Ca0.33Mn1− x Ti x O3 (x⩽0.10). The ferromagnetic-metallic ground state modifies to a glassy insulator for x⩾0.05. No field induced metallic state could be discerned for x=0.10 even at a field of 8T and at as low a temperature as 4.2K. Ti substitution significantly enhances the colossal magnetoresistance (CMR) effect. Both the metal to insulator transition temperature and Curie temperature (T c) decrease at a rate of ∼26K/at% up to x=0.05. T c levels off for higher compositions. Modification of the major carrier concentration (decreased Mn4+ concentration) seems to be insufficient to account for the observed reduction in the transition temperatures. This in turn emphasizes the significance of local structural effects: systematic elongation of the Mn–O bond lengths and decrease of Mn–O–Mn angles leading to strong suppression of itinerant ferromagnetism and metallicity of the compounds. The additional features in the ac susceptibility, viz., a broad shoulder just below T c followed by a sharp decrease in the susceptibility signal at low temperatures and a non-closure of MR at zero field as high as ∼75% at 5K indicate a frustrated magnetic ground state for x=0.07. Based on the inter-comparison of the structural, electrical transport and magnetic properties of the Mn site substituted La0.67Ca0.33MnO3 with iso-valent diamagnetic and paramagnetic ions, we argue that local structural effects have a decisive role to play, compared to the local spin coupling effects, in the ferromagnetic-metallic ground state of the CMR manganites. [Copyright &y& Elsevier]

Solar cycle-23 witnessed many successive intense X-ray solar flares and coronal mass ejections (CME) during the peak activity period, as well as in the descending phase of the cycle. Some of these emissions had large solar energetic particle events associated with them. When such solar ejecta impact the Earth's magnetosphere, they cause large scale disturbances in the geomagnetic field known as geomagnetic storms. Large variability in the occurrence characteristics of geomagnetic storms is controlled ultimately by the solar activity. Thus the changes in the interplanetary conditions are distinctly seen in the low latitude geomagnetic records as each storm event differs from the other. Several intense storm events of solar cycle-23 are analyzed for assessing the role of interplanetary magnetic field components By (east-west) and Bz (north-south) in controlling the generation and development of various types of storms. [ABSTRACT FROM AUTHOR]

Experiments show that the performance of the plasma focus (PF) depends on several macroscopic parameters like the energy of the capacitor bank, current, voltage, electrodes dimension, and curvature of current sheath in the axial phase. Recent work (IEEE Trans. Plasma Sci., vol. 24, no. 3, pp. 1101–1105, 1996) shows that overriding the dependence of performance on the individual parameters listed above is the dependence on a combined parameter called the drive or speed parameter S : (Ip/a)/ √ρ. This parameter S appears as most fundamental in the process of nondimensionalization of the magnetohydrodynamic equations coupling the highly supersonic motion of the plasma layer with the electromagnetic circuit equation. The drive parameter S is found to directly control the speed of the plasma layer in both axial and radial phases of the PEA literature survey (IEEE Trans. Plasma Sci., vol. 24, no. 3, pp. 1101–1105, 1996) first pointed out that neutron-optimized Mather-type PF devices with a range of energies from a few kilojoules to hundreds of kilojoules all operate with a remarkably constant drive parameter. This constancy of S has been extended more recently (Plasma Phys. Control. Fusion, vol. 47, pp. A361–A381, 2005) to PF devices over eight orders of magnitude of storage energies, from a fractional of a joule to megajoules. In this paper, experiments on 2–3,kJ dense PF with modified anodes have been conducted to show that this drive parameter remains fairly constant for the different ratios of the anode length to anode radius. It is also suggested that there may be significant differences in the values of drive parameters for Filippov-type focus devices, Mather-type focus devices, and also hybrid-type devices. [ABSTRACT FROM AUTHOR]

Abstract: Conductivity vs. temperature (σ–T) at zero and 8-T field, magneto-resistance (Δρ/ρ), magnetization vs. temperature (M–T) and magnetization vs. field (M–H) of Al70.5Pd22Mn7.5 quasicrystal have been studied in the temperature range of 1.4K to 300K. The σ–T variations in both the field conditions show a σ–T minima. In addition to this the σ–T variation at 8T shows a maxima also at ∼6K. Comparative analysis shows that the observed σ–T minima arises due to competing inelastic scattering events in the presence of weak-localization effect. These events are e–ph scattering in the dirty-metallic limit (τ i ∝ T −2), and the Kondo-type spin-flip scattering (τ sf). The maxima observed for the σ–T variation at 8T, has been attributed to suppression of the spin-flip scattering in the presence of field. The magneto-resistance is found to be large and positive. It was properly accounted only when the Stoner-enhancement, found in the case of spin fluctuating systems, was taken into consideration. [Copyright &y& Elsevier]

The electrical conductivity and magnetization behaviour of single-phase Al 70-x B x Pd 20 Mn 10 (x?=?0, 0.5, 1, 2 and 4) quasicrystals have been measured. We observe that boron substitution for aluminium causes large changes in the s vs. T behaviours. s vs. (ln?T) -1 plots shows linear behaviour. Scaling was achieved by plotting {(s(T)?-?s min )/(s 4 ?-?s min )} vs. [ln(T/T min )] -1 . These samples show large positive magnetoresistance with H 2 behaviour. In the Al–B–Pd–Mn and Al–Pd–Mn quasicrystals, the observed s(T) behaviour has been explained using the weak localization theory, including Kondo-type spin-flip scattering and not due to spin-orbit scattering. [ABSTRACT FROM AUTHOR]