A theoretical analysis of the excited states in 2-benzoylthiophene

The lower excited states of 2-benzoylthiophene have been studied using ab initio quantum chemical methods based on multiconfigurational wave functions. Six singlet and six triplet excited states have been characterized. The geometry has been optimized for the two lowest triplet states, which are responsible for the photoreactivity of the chromophore in the photosensitizing drug tiaprofenic acid. The T¹(π → π?) and T₂(n → π?) states have been found to be close in energy with the π → π? state slightly lower. The excited states have been characterized using density difference and spin density plots. The different photochemical behaviour of the two triplet states can be rationalized from the theoretical data.     

Numerical solution of fractionally damped beam by homotopy perturbation method

This paper investigates the numerical solution of a viscoelastic continuous beam whose damping behaviours are defined in term of fractional derivatives of arbitrary order. The Homotopy Perturbation Method (HPM) is used to obtain the dynamic response. Unit step function response is considered for the analysis. The obtained results are depicted in various plots. From the results obtained it is interesting to note that by increasing the order of the fractional derivative the beam suffers less oscillation. Similar observations have also been made by keeping the order of the fractional derivative constant and varying the damping ratios. Comparisons are made with the analytic solutions obtained by Zu-feng and Xiao-yan [Appl. Math. Mech. 28, 219 (2007)] to show the effectiveness and validation of this method.     

First principle studies on structural,electronic, elastic,optical, and thermoelectric properties of XGeCl3 (X = Rb/Cs): Promising compounds for green energy application

This study employed density functional theory (DFT) embedded in Wien2K code to evaluate the physical features of the XGeCl₃ (X = Rb/Cs) cubic halide perovskites. The structural optimization has been performed considering generalized gradient approximation (GGA) and electronic properties have been computed considering modified Becke-Johnson potential (mBJ). The formation energy and phonon dispersion analysis establish the stability of the investigated compounds. Mechanical stability is further confirmed by the computed diverse elastic coefficients. It has been discovered that the examined substances are naturally ductile. The refractive index, reflectivity, and absorption coefficient, are among the optical parameters that have been estimated and analyzed. Interesting results have been obtained for the transport properties of XGeCl₃ (X = Rb/Cs). The XGeCl₃ (X = Rb/Cs) exhibits a high Seebeck coefficient (X = Rb/Cs) and the largest figure of merit (about 0.99), indicating significant potential for thermoelectric applications.     

High temperature drop calorimetry measurements of enthalpy increment in Ti–xTa (x=5, 10, 15, 20 mass%) alloys

The enthalpy increment for a series of Ti–xTa (x=5, 10, 15, 20 mass%) alloys, having α(hcp)+β(bcc) two phase microstructure has been measured using inverse drop calorimetry in the temperature range 463–1257 K. The studies clearly revealed the occurrence of α→β diffusional phase transformation. Both the α→β transformation onset temperatures and the measured transformation enthalpy Δ⁰H_tr^α→β exhibit progressively lower values with increasing Ta content. It is found that the measured enthalpy in the transformation region is constituted of two principal contributions namely, (i) the enthalpy due to untransformed α and coexisting β phases and (ii) the transformation enthalpy due to α→β phase change. Since the fractional extent of α→β transformation varies continuously with temperature, the measured enthalpy variation in the transformation domain has been modeled using Kolmogorov–Johnson–Mehl–Avrami formalism for the diffusional transformation kinetics. The thermodynamic quantities for all the alloys have been derived.     

Doping of the Processable Conducting Poly(m-Aminophenol) with Inorganic Acids

Poly(m-aminophenol) (PmAP) was synthesized from m-aminophenol (mAP) in aqueous sodium hydroxide (NaOH) using ammonium persulfate (APS) as an oxidative initiator. Free standing PmAP films were cast from dimethyl sulfoxide (DMSO) solution of the polymer. Then the film was doped with various inorganic acids using a solution doping technique. Various inorganic acid doped PmAP films were characterized by ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR), and energy dispersive X-ray (EDS) spectroscopies, X-ray diffraction (XRD) analysis and elemental (C, H, N, S, O) analysis. All the results were explained on a comparative basis and the doping scheme was proposed. The DC-conductivity of the inorganic acid doped films was measured using a standard four-probe method. From the DC-conductivity measurements it was found that sulfuric acid had a better doping effect in terms of conductivity than that of the other inorganic acids used, perchloric acid and phosphoric acid. An explanation of the reason for the better doping effect of sulfuric acid than that of the other inorganic acids is given.     

Experimental Investigation into the Mechanical Behavior of Textile Composites with Various Fiber Reinforcement Architectures

Mechanics of Composite Materials - The role of fiber reinforcement architecture in adjusting the mechanical properties of glass-fiber-reinforced epoxy composite materials is studied. Fibrous...     

Distinct Helical Molecular Orbitals through Conformational Lock**

Several theoretical studies have proposed strategies to generate helical molecular orbitals (Hel-MOs) in [n]cumulenes and oligoynes. While chiral even-[n] cumulenes feature Hel-MOs, odd-[n] cumulenes may also present them if the terminal groups lie in different planes. However, the proposed systems have been either experimentally unfeasible or resulted in opposite pseudo-degenerated Hel-MOs. We hereby demonstrate the introduction of a remarkable energy difference between helical orbitals of opposite twist by fixing the torsion angle between the terminal groups in butadiyne fragments. To experimentally lock the conformation of the terminal groups, we designed and synthesized cyclic architectures by combining acetylenes with chiral spirobifluorenes. The high stability of these systems with distinct helical orbitals allowed their isolation and full characterization. In our view, these results constitute a step further in the development of real systems presenting helical molecular orbitals.     

II: PROPERTIES OF DIATOMIC AND TRIATOMIC MOLECULES

Results are presented from a theoretical study of the × ⁶Σ⁺, A ⁶Σ⁺ and ⁶Δ electronic states of CrH using multiconfiguration second-order perturbation theory in the multi-state formalism (MS-CASPT2). It is shown that the results for the spectroscopic constants and radiative lifetimes for the A state are in agreement with experiment and an earlier multireference configuration interaction study only if the two close lying × and A states are allowed to interact at a level of approximation that includes dynamic correlation.