Investigation of Structural, Magneto-transport, and Electronic properties of Pr0.7Sr0.3MnO3 nanoparticle

In this report Micro-structural, magnetic, electronic, and magneto-transport properties of perovskite Pr0.7Sr0.3MnO3 manganite nanoparticles have been thoroughly investigated. A series of samples with different particle size (Φ) is synthesized by chemical pyrophoric reaction process. Rietveld refinement of X-Ray diffraction pattern of the sample showed single phase orthorhombic structure with Pbnm space group. Metal- insulator transition () has been observed in the temperature range of 180-200 K in zero field resistivity data (2300 K) and it differs from ferromagnetic to paramagnetic transition temperature () due to enhanced surface disorder effect. The lowest nanomentric sample exhibit maximum 85 % magneto-resistances under 8 T magnetic field at 4 K. Magneto-impedance measurement of the Pr0.7Sr0.3MnO3 nano particles have been obtained at 0.8 T in the temperature range 80-300 K. The magneto transport properties has been explored with spin polarized tunneling and spin dependent scattering of single ferromagnetic domain with nanometric grain size modulation. We have analyzed temperature dependent resistivity data using small polaron hopping and variable range hopping models. Below < 40 K a resistivity upturn behavior exhibiting a distinct resistivity minimum has been observed for each sample, which is best explained by electron-electron interaction and weak localization mechanism

Centrality, transverse momentum and collision energy dependence of the Tsallis parameters in relativistic heavy-ion collisions

The thermodynamic properties of matter created in high-energy heavy-ion collisions have been studied in the framework of the non-extensive Tsallis statistics. The transverse momentum ($p_{\rm T}$)~spectra of identified charged particles (pions, kaons, protons) and all charged particles from the available experimental data of Au-Au collisions at the Relativistic Heavy Ion Collider (RHIC) energies and Pb-Pb collisions at the Large Hadron Collider (LHC) energies are fitted by the Tsallis distribution. The fit parameters, $q$ and $T$ measure the degree of deviation from an equilibrium state and the effective temperature of the thermalized system, respectively. The $p_{\rm T}$~spectra are well described by the Tsallis distribution function from peripheral to central collisions for the wide range of collision energies, from $\sqrt{s_{\rm NN}}$ = 7.7 GeV to 5.02 TeV. The extracted Tsallis parameters are found to be dependent on the particle species, collision energy, centrality, and fitting ranges in $p_{\rm T}$. For central collisions, both $q$ and $T$ depend strongly on the fit ranges in $p_{\rm T}$. For most of the collision energies, $q$ remains almost constant as a function of centrality, whereas $T$ increases from peripheral to central collisions. For a given centrality, $q$ systematically increases as a function of collision energy whereas $T$ has a decreasing trend. A profile plot of $q$ and $T$ with respect to collision energy and centrality shows an anti-correlation between the two parameters.Comment: 12 pages, 10 figure

Emergence of size induced metallic state in the ferromagnetic insulating Pr0.8Sr0.2MnO3 manganite: Breaking of surface polarons

Nano-dimensional effects on electronic-, magneto-transport properties of granular ferromagnetic insulating (FMI) Pr0.8Sr0.2MnO3 (PSMO) manganite (down to 40 nm) have been investigated in details. From the electronic and magnetic transport properties, a metallic state has been observed in grain size modulation by suppressing the ferromagnetic insulating state of PSMO bulk system. A distinct metal-insulator transition (MIT) temperature around 150 K has been observed in all nanometric samples. The observed insulator to metallic transition with size reduction can be explained with surface polaron breaking model, originates due to enhanced grain surface disorder. This proposed phenomenological polaronic model plays a significant role to understand the polaronic destabilization process on the grain surface regime of these phase separated nano-mangnatie systems. Temperature dependent resistivity and magnetoresistance data in presence of external magnetic fields are investigated in details with various compatible models

Synthesis, spectra and redox properties of mononuclear five-co-ordinate copper(II) complexes with non-communicable pyrazole/pyridyl containing ligands: X-ray structure of [2,6-bis(3,5-dimethyl-pyrazol-1-ylmethyl)pyridine][2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine]copper(II) diperchlorate

Synthesis and characterization of a series of five-co-ordinate mononuclear copper(II) compounds (1-8) have been achieved using 1 tridentate / bidentate heterocyclic nitrogen donor ligands with mixed hard-soft donor sets [L1 = 2,6-bis(pyrazol-1-ylmethyl)pyridine; L2 = 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine; L3 = 2-(pyrazol-1-ylmethyl)pyridine; L4 = 2-(3,5-dimethylpyrazol-1-ylmethyl)- pyridine]. Two types of complexes have been synthesized: (i) the anion bound complexes [Cu(L1/L2 )X2] (X=Cl- 1and 2; N-3 3 and 4; SCN- 5 and 6) and (ii) mixed-ligand complexes [Cu(L1/L2)(L3/L4)](ClO4)2 7 and 8. Complexes 1-8 belong to only a handful of copper(II) complexes with this class of non-planar ligands where pyrazole and pyridine rings are separated by methylene spacer(s). A representative complex [Cu(L2)(L4)](ClO4)2 8, having CuN5 co-ordination sphere, has been structurally characterized, to reveal square pyramidal stereochemistry at the copper(II) centre. Conductivity measurements revealed that one of the co-ordinated anions in 3, 5 and 6 is dissociated in solution, with the vacant site occupied by solvent molecule. Absorption and EPR spectral features of 1-8 represent that these copper(II) complexes adopt essentially a square pyramidal geometry. However, for 1 both in the solid state as well as in solution and for 2 in solution we propose that the copper(II) centre could be six-co-ordinate. Cyclic voltammetric measurements reveal the following trends in their E½ values (CuII -CuI redox process): (i) relative stabilization of CuII state by anionic ligands (N-3, Cl- or NCS- ) and a strongly co-ordinating solvent like DMF and (ii) predominance of steric over electronic effect (L1 vs. L2)

Analysis of National Forest Programs for REDD+ Implementation in six South and Southeast Asia countries

Aim of study: To facilitate REDD+ implementation and identify relevant attributes for robust REDD+ policies, this study evaluated and synthesized information from national forest programs in South and Southeast Asian countries.Area of study: Data was collected from six countries: Sri Lanka, Indonesia, Bangladesh, Philippines, India and Thailand.Methods: The data sources for the evaluation was an in-depth desk review of relevant documents and focus group discussion among experts from each study country.  Main Results: We found out that diverse factors may influence program feasibility and the ability to achieve ‘triple benefits’: the nature of the forest targeted by the policy, the characteristics of the population affected by the policy, attributes of the policy instrument and the different actors involved.Research highlights: We argue that national policies and programs targeted for REDD+ implementation should focus on the identified features to achieve REDD+ goals.Keywords: policy evaluation; policy instruments; triple benefits; Southeast Asia

The plastic waste problem in Malaysia: management, recycling and disposal of local and global plastic waste

Plastic waste is one of the world’s most pressing human health and environmental concerns. Plastic constitutes the third highest waste source globally, with the total volume of plastic waste growing in-line with increases in the global population and per capita consumption. Malaysia is tracking global trends in both the overall generation of plastic waste and the consumption of single-use plastics and since 2017 has been the world’s largest importer of plastic waste. These elements create a number of major challenges for the country’s waste management system. This review outlines the current state of plastic waste production and management in Malaysia, including options for landfill, recycling and incineration. It presents information on the scale and both the human and ecological risks of plastic waste in the country (i.e. microplastics, landfill, incineration), outlines key plastic waste management policy initiatives (including plastics alternatives such as biodegradable plastics) and highlights key constraints on the success of these. Significant internal constraints stem from the inconsistent application of policy initiatives by state governments, in addition to the lack of public awareness and interest in household recycling. The paper closes by discussing options for and constraints on the switch to biodegradable alternatives and proposes a model of plastic management based on a circular economy approach and solid waste management hierarchy. Success in reducing the problems posed by plastic in Malaysia will require sustained effort at many levels, but positive experiences in other countries give some cause for optimism

Challenges and considerations of applying nature-based solutions in low- and middle-income countries in Southeast and East Asia

Low- and middle-income countries in Southeast and East Asia face a range of challenges related to the rapid pace of urbanisation in the region, the scale of pollution, climate change, loss of ecosystem services and associated difficulties for ecological restoration. Possible pathways towards a more sustainable future lie in the applications of nature-based solutions (NBS). However, there is relatively little literature on the application of NBS in the region, particularly Southeast Asia. In this paper we address this gap by assessing the socio-ecological challenges to the application of NBS in the region – one of the most globally biodiverse. We first provide an overview and background on NBS and its underpinnings in biodiversity and ecosystem services. We then present a typology describing five unique challenges for the application of NBS in the region: (1) Characteristics of urbanisation; (2) Biophysical environmental and climatic context; (3) Environmental risks and challenges for restoration; (4) Human nature relationships and conflicts; and (5) Policy and governance context. Exploiting the opportunities through South-South and North-South collaboration to address the challenges of NBS in Southeast and East Asia needs to be a priority for government, planners and academics.Peer reviewe

Tree species that 'live slow, die older' enhance tropical peat swamp restoration : Evidence from a systematic review

Degraded tropical peatlands lack tree cover and are often subject to seasonal flooding and repeated burning. These harsh environments for tree seedlings to survive and grow are therefore challenging to revegetate. Knowledge on species performance from previous plantings represents an important evidence base to help guide future tropical peat swamp forest (TPSF) restoration efforts. We conducted a systematic review of the survival and growth of tree species planted in degraded peatlands across Southeast Asia to examine (1) species differences, (2) the impact of seedling and site treatments on survival and growth and (3) the potential use of plant functional traits to predict seedling survival and growth rates. Planted seedling monitoring data were compiled through a systematic review of journal articles, conference proceedings, reports, theses and unpublished datasets. In total, 94 study-sites were included, spanning three decades from 1988 to 2019, and including 141 indigenous peatland tree and palm species. Accounting for variable planting numbers and monitoring durations, we analysed three measures of survival and growth: (1) final survival weighted by the number of seedlings planted, (2) half-life, that is, duration until 50% mortality and (3) relative growth rates (RGR) corrected for initial planting height of seedlings. Average final survival was 62% and half-life was 33 months across all species, sites and treatments. Species differed significantly in survival and half-life. Seedling and site treatments had small effects with the strongest being higher survival of mycorrhizal fungi inoculated seedlings; lower survival, half-life and RGR when shading seedlings; and lower RGR and higher survival when fertilising seedlings. Leaf nutrient and wood density traits predicted TPSF species survival, but not half-life and RGR. RGR and half-life were negatively correlated, meaning that slower growing species survived for longer. Synthesis and applications. To advance tropical peat swamp reforestation requires expanding the number and replication of species planted and testing treatments by adopting control vs. treatment experimental designs. Species selection should involve slower growing species (e.g. Lophopetalum rigidum, Alstonia spatulata, Madhuca motleyana) that survive for longer and explore screening species based on functional traits associated with nutrient acquisition, flooding tolerance and recovery from fire.Peer reviewe