Copolymerization of 2-methyl-N-1,3-thiazole-2-ylacrylamide with glycidyl methacrylate: synthesis, characterization, reactivity ratios and biological activity

The free-radical copolymerization of 2-methyl-N-1,3-thiazole-2-ylacrylamide monomer (TMA) with glycidyl methacrylate (GMA) was carried out in 1,4-dioxane at 65 ± 1 °C using azobisisobutironitril (AIBN) as an initiator. The copolymers were characterized by FTIR, ¹³C-NMR and ¹H-NMR spectroscopic methods. The copolymer compositions were determined by elemental analysis. The weight-average and number-average molecular weights of the copolymers were obtained by gel permeation chromatography (GPC). The polydispersity indices of the polymers, determined with gel permeation chromatography, suggested a strong tendency for chain termination by disproportionation. Thermal properties of the polymers were also studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The monomer reactivity ratios were calculated according to the general copolymerization equation using Kelen–Tudos and Fineman–Ross linearization methods. The reactivity ratios indicated a tendency toward for alternation. The thermal decomposition activation energies of the polymers were evaluated by Ozawa method. The antibacterial and antifungal effects of the copolymers were also investigated on various bacteria and fungi. All the products showed moderate activity against different strains of bacteria and fungi.     

On nonlocal microfluid mechanics

The simple microfluid theory of Eringen [1] is generalized to include nonlocal effects. The balance laws, jump conditions, and constitutive equations are obtained. The nonlocal intermolecular forces, energy and entropy are accounted for by nonlocal field residuals and functional constitutive equations of space type. The second law of thermodynamics is used to obtain specific forms of these residuals, constitutive equations and restrictions to be imposed. The linear theory is developed fully for the micromorphic and micropolar nonlocal fluids. The nonlocal effects are shown to include surface tension and surface stresses. Passage is made to material gradient theories.     

A continuum theory of rigid suspensions

A continuum theory of rigid suspension is presented. The theory modifies and extends the Batchelor^1,2 theory of fiber suspensions to heat conducting thermo-viscous Newtonian solvents carrying rigid suspensions.     

Edge dislocation in nonlocal elasticity

The solution is presented for the problem of straight edge dislocation in nonlocal elasticity. The stress field and elastic energy are calculated. Classical singularities in the expressions of the stress field and stored energy are found not present in the nonlocal model. An estimate is made for the critical shear stress which will produce a single edge dislocation of one atomic distance.     

Oxidation and thermal shock behavior of thermal barrier coated 18/10CrNi alloy with coating modifications

In this study, substrates of 18/10CrNi alloy plates were initially sprayed with a Ni-21Cr-10Al-1Y bond coat and then with an yttria stabilized zirconia top coat by plasma spraying. Subsequently, plasma-sprayed Thermal barrier coatings (TBCs) were treated with two different modification methods, namely, vacuum heat treatment and laser glazing. The effects of modifications on the oxidation and thermal shock behavior of the coatings were evaluated. The effect of coat thickness on the bond strength of the coats was also investigated. Results showed enhancement of the oxidation resistance and thermal shock resistance of TBCs following modifications. Although vacuum heat treatment and laser glazing exhibited comparable results as per oxidation resistance, the former generated the best improvement in the thermal shock resistance of the TBCs. Bond strength also decreased as coat thickness increased.     

Electrochemical impedance spectroscopy of poly(N-methyl pyrrole) on carbon fiber microelectrodes and morphology

This work reports the supercapacitive properties of electrochemically grown homopolymer films on carbon fiber microelectrode (CFME) via poly(N-methyl pyrrole) (P(NMPy)) which is characterized by cyclic voltammetry (CV), Fourier transform infrared reflectance (attenuated total reflection) spectroscopy (FTIR-ATR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). Microporosity of P(NMPy) electrocoated carbon fiber microelectrodes facilitated improved capacitance and redox behaviours by applying different DC potentials in electrochemical impedance spectroscopic measurements. The capacitance values of P(NMPy)/CFME is obtained (0.059 F) which is in the range of manufactured values.     

Heterojunction solar cells with integrated Si and ZnO nanowires and a chalcopyrite thin film

ZnO nanowires (NWs) have been successfully synthesized using a hydrothermal technique on both glass and silicon substrates initially coated with a sputtered ZnO thin film layer. Varying ZnO seed layer thicknesses were deposited to determine the effect of seed layer thickness on the quality of ZnO NW growth. The effect of growth time on the formation of ZnO NWs was also studied. Experimental results show that these two parameters have an important effect on formation, homogeneity and vertical orientation of ZnO NWs. Silicon nanowires were synthesized by a Ag-assisted electroless etching technique on an n-type Si (100) wafer. SEM observations have revealed the formation of vertically-aligned Si NWs with etching depth of ∼700 nm distributed over the surface of the Si. An electron-beam evaporated chalcopyrite thin film consisting of p-type AgGa_0.5In_0.5Se₂ with ∼800 nm thickness was deposited on the n-type ZnO and Si NWs for the construction of nanowire based heterojunction solar cells. For the Si NW based solar cell, from a partially illuminated area of the solar cell, the open-circuit voltage, short-circuit current density, fill factor and power conversion efficiency were 0.34 V, 25.38 mA cm⁻², 63% and 5.50%, respectively. On the other hand, these respective parameters were 0.26 V, 3.18 mA cm⁻², 35% and 0.37% for the ZnO NW solar cell.     

Smartphone addiction and its relationship with social anxiety and loneliness

Individuals with psychosocial problems such as social phobia or feelings of loneliness might be vulnerable to excessive use of cyber-technological devices, such as smartphones. We aimed to determine the relationship of smartphone addiction with social phobia and loneliness in a sample of university students in Istanbul, Turkey. Three hundred and sixty-seven students who owned smartphones were given the Smartphone Addiction Scale (SAS), UCLA Loneliness Scale (UCLA-LS), and Brief Social Phobia Scale (BSPS). A significant difference was found in the mean SAS scores (p?<?.001) between users who declared that their main purpose for smartphone use was to access social networking sites. The BSPS scores showed positive correlations with all six subscales and with the total SAS scores. The total UCLA-LS scores were positively correlated with daily life disturbance, positive anticipation, cyber-oriented relationship, and total scores on the SAS. In regression analyses, total BSPS scores were significant predictors for SAS total scores (β?=?0.313, t?=?5.992, p?<?.001). In addition, BSPS scores were significant predictors for all six SAS subscales, whereas UCLA-LS scores were significant predictors for only cyber-oriented relationship subscale scores on the SAS (β?=?0.130, t?=?2.416, p?<?.05). The results of this study indicate that social phobia was associated with the risk for smartphone addiction in young people. Younger individuals who primarily use their smartphones to access social networking sites also have an excessive pattern of smartphone use.     

Additive manufacturing of PA12 carbon nanotube composites with a novel laser polymer deposition process

The facile manufacture of PA12 MWCNT/silica (50/50 by weight) nanocomposite powders through a high energy mixing process is presented, which are useful to generate 3D objects by a novel Laser Polymer Deposition (LPD) process. The mixing as well as the LPD process led to no discernible changes in the material properties (DSC, SEM, LD) of the core-shell nanocomposites, enabling the recycling of unconverted powder. The built parts yield ultimate tensile stresses and Young's modulus at 10%–20% of the bulk material. Partially unmolten particles and voids were identified as the main mechanical failure mechanism in the built parts. The mechanical properties are better with low additive content (Young's modulus: 89.8 ± 5.4 MPa; UTS: 12.9 ± 5.3 MPa with 0.25 wt% additives). Electronic conductivity up to the region of moderate conductivity could be achieved by multiwalled carbon nanotube (MWCNT) network formation (8 × 10⁻⁴ S cm⁻¹ at 1.25 wt% of additives). A variant of the processing strategy revealed that a higher mechanical strength can be achieved by a laser induced remelting of the traces following their initial construction.