Proton‐Conducting Magnetic Coordination Polymers

Three isostructural lanthanide‐based two‐ dimensional coordination polymers (CPs) {[Ln₂(L)₃(H₂O)₂]_n ? 2n CH₃OH) ? 2n H₂O} (Ln=Gd³⁺ ( 1 ), Tb³⁺ ( 2 ), Dy³⁺ ( 3 ); H₂L=cyclobutane‐1,1‐dicarboxylic acid) were synthesized by using a low molecular weight dicarboxylate ligand and characterized. Single‐crystal structure analysis showed that in complexes 1 – 3 lanthanide centers are connected by μ₃‐bridging cyclobutanedicarboxylate ligands along the c axis to form a rod‐shaped infinite 1D coordination chain, which is further linked with nearby chains by μ₄‐connected cyclobutanedicarboxylate ligands to form 2D CPs in the bc plane. Viewing the packing of the complexes down the b axis reveals that the lattice methanol molecules are located in the interlayer space between the adjacent 2D layers and form H‐bonds with lattice and coordinated water molecules to form 1D chains. Magnetic properties of complexes 1 – 3 were thoroughly investigated. Complex 1 exhibits dominant ferromagnetic interaction between two nearby gadolinium centers and also acts as a cryogenic magnetic refrigerant having a significant magnetic entropy change of ?ΔS_m=32.8 J kg^?1 K^?1 for ΔH=7 T at 4 K (calculated from isothermal magnetization data). Complex 3 shows slow relaxation of magnetization below 10 K. Impedance analysis revealed that the complexes show humidity‐dependent proton conductivity (σ=1.5×10^?5 S cm^?1 for 1 , σ=2.07×10^?4 S cm^?1 for 2 , and σ=1.1×10^?3 S cm^?1 for 3 ) at elevated temperature (>75 °C). They retain the conductivity for up to 10 h at high temperature and high humidity. Furthermore, the proton conductivity results were correlated with the number of water molecules from the water‐vapor adsorption measurements. Water‐vapor adsorption studies showed hysteretic and two‐step water vapor adsorption (182000 μL g^?1 for 1 , 184000 μL g^?1 for 2 , and 1874000 μL g^?1 for 3 ) in the experimental pressure range. Simulation of water‐vapor adsorption by the Monte Carlo method (for 1 ) confirmed the high density of adsorbed water molecules, preferentially in the interlayer space between the 2D layers.     

Synthesis of Nitrogen Doped Multilayered Graphene Flakes: Selective Non‐enzymatic Electrochemical Determination of Dopamine and Uric Acid in presence of Ascorbic Acid.

Nitrogen doped multilayered graphene (NDMLG) is synthesized by annealing the black fluffy mass obtained by decomposing the complex prepared from Zn(OAc)₂, diethanolamine and triethanolamine. The NDMLG has been characterized by HRTEM, FESEM, XRD, XPS, Raman spectroscopy, BET which indicate formation of nitrogen doped multilayer graphene flakes with high surface area. NDMLG shows better electrochemical oxidation property towards Dopamine, Uric acid and Ascorbic acid. The linear response ranges for determination of DA, UA and AA are 0.5–150 µM, 3–60 µM and 80–2000 µM respectively and the detection limits (S/N=3) are 15 nM, 15 nM, 580 nM, respectively in the mixture.     

Solution‐Based Synthesis of Layered Intergrowth Compounds of the Homologous PbmBi2nTe3n+m Series as Nanosheets

Layered intergrowth compounds in the homologous Pb_mBi_2nTe_3n+m family are interesting because they are examples of natural heterostructures. We present a simple solution‐based synthesis of two‐dimensional nanosheets of PbBi₂Te₄, Pb₂Bi₂Te₅, and PbBi₆Te₁₀ layered intergrowth compounds, which are members of the Pb_mBi_2nTe_3n+m [that is, (PbTe)_m(Bi₂Te₃)_n] homologous series. Few‐layer nanosheets exhibit narrow optical band gaps (0.25–0.7 eV) with semiconducting electronic‐transport properties.     

Uranium in ground water of Rajnandgaon District of Central India

The present study highlights uranium levels, associated health effects, and physicochemical properties of ground water samples collected from Rajnandgaon District of Chhattisgarh State, Central India. Uranium concentrations of ground water samples are found to exceed than 30 µg/L (United States Environmental Protection Agency and World Health Organisation recommended limit) at two villages in summer and at one village in winter while it is found higher than 60 µg/L (Atomic Energy Regulatory Board, Department of Atomic Energy, India recommended limit) at only one village in summer. Correlation analysis between uranium and physicochemical parameters suggest that Ca²⁺ ion and total alkalinity play an important role in uranium contamination of ground water.

     

All- optical phase encoded 4-to-1 phase multiplexer using four wave mixing in semiconductor optical amplifier

Optics has already showed its potency over its electronic complements in case of superfast computing and communication systems. Semiconductor optical amplifier, (SOA) with its several nonlinear properties, plays a very crucial role in the development of high-speed all-optical processor. Multiplexer and demultiplexer are the extremely important element of the processor which takes part in utilizing different actions like encoding, decoding, routing, and the different process of data conversion and generation, etc. In this paper, the authors have proposed a scheme of phase encoded all-optical phase multiplexer using four wave mixing (FWM) property of semiconductor optical amplifier. Thus, the improved tolerance against fiber-nonlinearity and higher receiver sensitivity of phase encoding method with the fast occurring processes like FWM in SOA offers higher speed in this proposed scheme of multiplexing.     

Enhanced output voltage of nano energy harvester with diverse textiles

Abstract

We demonstrate the electrical properties of nano energy harvesters (NEHs) with various textiles for smart textiles that can be applied to the next generation wearable electronics. Output voltages and currents of NEHs with various fabrics, such as a cotton, rayon and wool that have different triboelectricity were measured. Cotton, rayon and wool shows the maximum output voltages of 1.250, 3.313 and 4.063 V, respectively. In addition, output currents of those textiles were 0.75, 4.4, 1.063 μA, respectively. Wool, in particular, which has the highest triboelectricity of 350 V exhibits the highest output voltage.     

Rapid Suzuki‐Miyaura cross‐coupling reaction catalyzed by zirconium carboxyphosphonate supported mixed valent Pd(0)/Pd(II) catalyst

Mixed valent Pd(0)/Pd(II) nano‐sized aggregates supported onto a chemically robust layered zirconium carboxyphosphonate framework is prepared and its catalytic activity in Suzuki‐Miyaura cross coupling reaction is explored. The exceptionally high catalytic efficacy of the heterogeneous catalyst in Suzuki‐Miyaura cross coupling reaction is signified by remarkably short reaction time 2 minutes and high turnover frequency of 1.3 x 10⁴ hr^?1. The catalyst can be recycled several times without significant loss of catalytic efficacy, while spectroscopic, structural and microscopic investigations suggest the integrity of the catalyst even after fifth catalytic cycle. The unique ability of the zirconium carboxyphosphonate framework to interact strongly with palladium in dual Pd(0)/Pd(II) oxidation states has been attributed to this remarkable augmentation of catalytic efficacy.