On studies of spontaneously emitted Cd I and Cd II lasing transitions

The effect of spatial variation with respect to metal surface, buffer gas (helium) pressure, temporal behavior on the intensity of spontaneously emitted Cd I and Cd II lasing transitions is reported. A strong dependence of intensity of the emitted spectrum on pressure of helium gas, indicating electron-ion recombination is observed. An estimate of temperature corresponding to recombination laser for Cd I and Cd II transitions is presented.     

Field emission theory of dislocation-sensitized photo-stimulated exo-electron emission from coloured alkali halide crystals

A new field emission theory of dislocation-sensitized photo-stimulated exo-electron emission (DSPEE) is proposed, which shows that the increase in the intensity of photo emission fromF-centres during plastic deformation is caused by the appearance of an electric field which draws excited electrons out of the deeper layer and, therefore, increases the number of electrons which reach the surface. The theory of DSPEE shows that the variation of DSPEE flux intensity should obey the following relation

Synthesis,characterization, and antibacterial activity of some thiazoles derived from allyl thioureas

Synthesis of thiazoles was carried out from allyl thioureas using different cyclizing agents such as hydrogen chloride gas and bromine. Synthesized compounds were characterized by IR, ¹H and ¹³C NMR, mass spectrometry, and elemental analysis. The synthesized thiazoles were evaluated for their antibacterial activity against Gram postitive (Lactobacillus bulgaris and Streptococcus mitis) and Gram negative (Yersinia) as well as antifungal activity against Aspergillus niger fungi.     

Preparation and characterization of reduced graphene oxide supported nickel oxide nanoparticle-based platform for sensor applications

A nanostructured composite film comprising reduced graphene oxide (rGO) and nickel oxide (NiO) nanoparticles (NPs) has been prepared and utilized for development of a simple yet efficient sensor for detection of dopamine and epinephrine in a single run. The hybrid material rGO-NiO nanocomposite was synthesized chemically, and the formation of nanocomposite was confirmed via X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, UV-Vis, and Fourier transform infrared (FTIR) spectroscopic techniques. The incorporation of NiO NPs on rGO support was found to provide improved sensing characteristics at electrode interface due to enhanced electron mobility on rGO sheet and high catalytic activity of NiO NPs. Subsequently, the synthesized rGO-NiO nanocomposite was deposited onto indium tin oxide (ITO)-coated glass substrate by simple drop-casting method, and the electrode was characterized through atomic force microscopy (AFM) and scanning electron microscopic (SEM) studies. After optimization of experimental conditions electrochemically for its high sensitivity, the fabricated rGO-NiO/ITO electrode was used for simultaneous detection of dopamine and epinephrine by square wave voltammetry (SWV) method. The results showed high sensitivity of 0.545 and 0.638 μA/μM for dopamine and epinephrine respectively in a broad linear range of 0.5–50 μM. Moreover, remarkable detection limits of 0.495 and 0.423 μM were found for dopamine and epinephrine, and the developed sensor exhibited a wide separation of 380 mV between the respective detection peaks of dopamine and epinephrine. Beside this, the proposed sensor was successfully applied in presence of high concentration of interfering agents, ascorbic acid and uric acid, and validated with real serum samples.     

Entropy of Quantum Dynamical Systems and Sufficient Families in Orthomodular Lattices with Bayessian State

The purpose of the present paper is to study the entropy hs（Ф） of a quantum dynamical systems Ф = （ L, s, Ф）, where s is a bayessian state on an orthomodular lattice L. Having introduced the notion of entropy hs（ Ф, A） of partition A of a Boolean algebra B with respect to a state s and a state preserving homomorphism Ф, we prove a few results on that, define the entropy of a dynamical system hs（Ф）, and show its invariance. The concept of sufficient families is also given and we establish that hs （Ф） comes out to be equal to the supremum of hs （Ф,A）, where A varies over any sufficient family. The present theory has then been extended to the quantum dynamical system （ L, s, Ф）, which as an effect of the theory of commutators and Bell inequalities can equivalently be replaced by the dynamical system （B, s0, Ф）, where B is a Boolean algebra and so is a state on B.     

Anomalous behavior of optogalvanic signal in a miniature neon discharge lamp

A strong optogalvanic effect has been observed in a negative glow of a miniature neon discharge lamp using tunable pulse dye laser pumped by a copper vapor laser. A comparative study on temporal evolution of optogalvanic signal in a positive and negative dynamic resistance region of the discharge is described. Dye laser beam was tuned to various neon transitions 1s_i → 2p_j (Paschen notations) within 570-617 nm wavelength range. Anomalous behavior of optogalvanic signal was observed at 588.2 nm for (1s₅ → 2p₂) neon transition at low discharge current (<220 μA). This anomalous behavior is the attributes of damped oscillations of optogalvanic signal that correlate with negative dynamic resistance (dV/di < 0) of the discharge. Penning ionization at low discharge current and small energy mismatch is assumed to be the main cause of the negative dynamic resistance. Penning ionization process has been explained by resonantly ionizing energy transfer via collisions between neon buffer gas atoms in the lowest metastable state (1s₅) and electrode sputtered atoms in ground state using their partial energy level diagram.     

8‐Aminoquinoline‐Assisted Synthesis and Crystal Structure Studies of Ferrocenyl Aryl Sulfones

A copper‐catalyzed 8‐aminoquinoline‐directed oxidative cross‐coupling of the C?H bond of ferrocene with sodium arylsulfinates has been achieved. The robust copper catalyst tolerates a range of methyl, tert‐butyl, bromo, chloro, iodo and nitro functional groups in the phenyl ring, and set the stage for the synthesis of substituted ferrocene sulfones. Furthermore, X‐ray crystal structure study on several ferrocenyl sulfones reveals the tetrahedral geometry around sulfur; interestingly, the O‐S‐O angle is larger than the electropositive substituent C‐S‐C angle which could be explained by Bent's rule. Further, unusual intramolecular O(S)???N(amide) short contacts (2.925–3) and O(S)???C=O were also noticed in ferrocenyl sulfones.     

A quarter of a century after its synthesis and with >200 papers based on its use, `Co(CO3)0.5(OH)·0.11H2O′ proves to be Co6(CO3)2(OH)8·H2O from synchrotron powder diffraction data

The successful attempt to solve the crystal structure of Co(CO₃)_0.5(OH)·0.11H₂O (denoted CCH ), based on synchrotron powder diffraction data, leads to a drastic revision of the chemical formula to Co₆(CO₃)₂(OH)₈·H₂O [hexacobalt(II) bis(carbonate) octahydroxide monohydrate] and to a hexagonal cell instead of the orthorhombic cell suggested previously [Porta et al. (1992). J. Chem. Soc. Faraday Trans. 88 , 311–319]. This results in a new structure‐type related to malachite involving infinite chains of [CoO₆] octahedra sharing edges along a short c axis, delimiting tunnels having a three‐branched star section. All reports discussing cobalt hydroxycarbonates ( CCH ) without any structural knowledge and especially its topotactic decomposition into Co₃O₄ have, as a result, to be reconsidered.     

The Three Avtars of the Chern-Simons Term in 3 Space-Time Dimensions

I discuss in detail the three “avtars” of the Chern-Simons (C-S) term in 2 + 1 dimensions i.e. (i) C-S term as gauge field mass term (ii) C-S term as a purely kinematic term (iii) gauge theories with purely C-S action. In the first case we find that because of the C-S term one has massive gauge quanta and still the theory is gauge invariant. Such a C-S term can be generated either by spontaneous symmetry breaking or by radiative corrections. The dramatic effect of this term is that the vortices of the abelian (or nonabelian) Higgs model now have finite, quantized charge and angular momentum. In the second case the C-S term is not really independent but can be expressed in terms of the basic quanta of the 0(3) nonlinear σ-model or CP¹ model. In either case one finds that due to this term the soliton of the model has fractional spin and statistic interpolating between fermions and bosons. The relevance of this in the context of high-T_c, superconductivity is discussed in some detail. Finally the third avtar has to do with some recent work of Witten where he has shown that the Hilbert spaces of the quantum Yang-Mills theory with pure C-S action can be interpreted as the spaces of the conformal blocks in 1 + 1 dimensional conformal theories.     

In-situ fabrication of barium titanate@polyvinyl pyrrolidone in polyvinylidene fluoride polymer nanocomposites for dielectric capacitor applications

We have demonstrated an in situ route to design barium titanate (BT)@polyvinyl pyrrolidone (PVP) nanoparticles (NPs) in PVP/polyvinylidene fluoride (PVDF) blends. Thus, the PVP simultaneously acted as a linker and a part of the polymer matrix. We have hydrothermally synthesized the tetragonal phase of BT NPs (~150 nm). The BT NPs content was varied from 0 to 15 vol%. The resulting polymer nanocomposites generated enormous interfaces because of homogeneously dispersed BT@PVP NPs. Furthermore, the PVP simultaneously tailored the interfacial properties surrounding the BT NPs and bulk of the polymer matrix. Therefore, we achieved an enhanced maximum polarization (P_max) and energy density (U_d) of 27.9 μC cm⁻² and 13.4 J cm⁻³ (2261 kV cm⁻¹), respectively, at 7.5 vol% BT NPs loadings. At the same time, PVP/PVDF blends showed P_max and U_d of only 3.9 μC cm⁻² and 4.6 J cm⁻³ (3369 kV cm⁻¹), respectively. This simple approach of in situ nanomaterials modification will lead to development of low-cost and time-efficient dielectric capacitors.