Chemical potential and internal energy of the noninteracting Fermi gas in fractional-dimensional space

Chemical potential and internal energy of a noninteracting Fermi gas at low temperature are evaluated using the Sommerfeld method in the fractional-dimensional space. When temperature increases, the chemical potential decreases below the Fermi energy for any dimension equal to 2 and above due to the small entropy, while it increases above the Fermi energy for dimensions below 2 as a result of high entropy. The ranges of validity of the truncated series expansions of these quantities are extended from low to intermediate temperature regime as well as from high to relatively low density regime by using the Padé approximant technique.     

Anion binding with some 22- and 28-membered selenaaza macrocycles: Structural aspects and Se NMR studies

A series of macrocyclic adducts of the 22- and 28-membered selenaaza macrocycles (1 and 2, respectively) with different counter anions such as halides, sulfate, perchlorate, phosphate, trifluoroacetate and nitrate has been prepared. The adducts have been characterized by elemental analysis, IR, ¹H NMR, ⁷⁷Se NMR and ESI-MS analysis. The ⁷⁷Se NMR spectrum of the adduct (7) shows an upfield shift compared to the parent macrocycle. The bromo (5), iodo (6), sulfate (7), trifluroacetate (10) adducts of the 22-membered selenaaza macrocycle and perchlorate (16), trifluroacetate (18) adducts of the 28-membered selenaaza macrocycle have been structurally characterized. The crystal structures show extensive hydrogen bonding networks. The molecular structures of all the compounds show the macrocycle to be fully protonated except the trifluroacetate adduct of the 22-membered macrocycle (10), which is only diprotonated. The binding constants of the neutral 22-membered selenaaza macrocycle towards, fluoride, bromide, iodide and sulfate ion have been determined by the NMR titration method.     

Studies on the adsorption of Brij-35 and CTAB at the coal-water interface

The adsorption behavior of polyoxyethylene (23) lauryl ether (Brij-35) and cetyl trimethyl ammonium bromide (CTAB) on coal sample has been studied. The adsorption process is found to be sensitive to pH, temperature, electrolyte concentration, and the amount of surface active agent. An attempt has been made to explain the adsorption behavior of the surfactants using the Langmuir equation. The extent of adsorption of Brij-35 on coal is found to be the highest at pH 2, which decreases with increase in pH and remains constant in the neutral and alkaline pH regions. But, the adsorption of CTAB exhibits the opposite behavior of that of Brij-35. Adsorption of any of the surfactant at the coal/water interface sharply decreases the apparent viscosity of 55 wt% coal-water slurry (CWS) at a shear rate of 100 s(-1). Electrostatic adsorption of the surfactants on the coal surface decreases the surface charge and renders the coal surface hydrophobic which is manifested in the form of high apparent viscosity of the coal-water slurry under the test conditions.     

Multi-item inventory models with price dependent demand under flexibility and reliability consideration and imprecise space constraint: A geometric programming approach

In this paper, multi-item economic production quantity (EPQ) models with selling price dependent demand, infinite production rate, stock dependent unit production and holding costs are considered. Flexibility and reliability consideration are introduced in the production process. The models are developed under two fuzzy environments–one with fuzzy goal and fuzzy restrictions on storage area and the other with unit cost as fuzzy and possibility–necessity restrictions on storage space. The objective goal and constraint goal are defined by membership functions and the presence of fuzzy parameters in the objective function is dealt with fuzzy possibility/necessity measures. The models are formed as maximization problems. The first one—the fuzzy goal programming problem is solved using Fuzzy Additive Goal Programming (FAGP) and Modified Geometric Programming (MGP) methods. The second model with fuzzy possibility/necessity measures is solved by Geometric Programming (GP) method. The models are illustrated through numerical examples. The sensitivity analyses of the profit function due to different measures of possibility and necessity are performed and presented graphically.     

Chemical Composition and Biological Activity of Essential Oil of Phoebe wightii

Chemistry of Natural Compounds -     

Compositional-dependent enhanced physicochemical and photovoltaic studies of nanocrystalline Ti1-xFexO2-δ photoelectrodes co-sensitized with CdS QDs-N719 dye

Journal of Solid State Electrochemistry - Ti1-xFexO2-δ nanoparticles (NPs) with varying content of Fe (III) ions (x = 0.008 to 0.024 and δ =0.5x) were synthesized using sol-gel method at...     

Poly(methyl methacrylate)-Assisted Exfoliation of Graphite and Its Use in Acrylonitrile-Butadiene-Styrene Composites

One of the applications of graphene in which its scalable production is of utmost importance is the development of polymer composites. Among the techniques used to produce graphene flakes, the liquid-phase exfoliation (LPE) of graphite stands out due to its versatility and scalability. However, solvents suitable for the LPE process are generally toxic and have a high boiling point, making the processing challenging. The use of low boiling point solvents could be convenient for the processing, due to the easiness of their removal. In this study, the use of poly(methyl methacrylate) (PMMA) as a stabilizing agent is proposed for the production of graphene flakes in a low boiling point solvent, that is, acetone. The graphene dispersions produced in the mixture acetone-PMMA have higher concentration, +175 %, and contain a higher percentage of few-layer graphene flakes (<5 layers), that is, +60 %, compared to the dispersions prepared in acetone. The as-produced graphene dispersions are used to develop graphene/acrylonitrile-butadiene-styrene composites. The mechanical properties of the pristine polymer are improved, that is, +22 % in the Young's modulus, by adding 0.01 wt. % of graphene flakes. Moreover, a decrease of ≈20 % in the oxygen permeability is obtained by using 0.1 wt. % of graphene flakes filler, compared to the unloaded matrix.