Effect of load changes on dynamic coefficient of friction of crystalline and amorphous materials

Journal of Materials Science Letters -     

Nepali children's ideas about emotional displays in hypothetical challenges.

Although culture plays an important role in specifying socially prescribed ways to communicate and act in emotional situations, few cultures have been studied. This study describes the ideas of 50 first-grade boys and girls (aged 6–9 years) from 2 different Nepali cultures (Tamang and Chhetri-Brahmin) regarding how they would feel and act in 6 emotionally challenging situations (e.g., peer conflict, family conflict). Significant cultural differences were found. Chhetri-Brahmin children were more likely than Tamang children to endorse negative emotions and to report masking negative emotion. These differences appeared to be related to socialization processes in the respective cultures. Chhetri-Brahmin mothers reported teaching their children about emotion, whereas Tamang mothers reported that children learned by themselves. The children's responses may reflect ideas about emotion regulation that emerge from the differing socioreligious contexts in which they live. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A scheme for mapping tolerance specifications to generalized deviation space for use in tolerance synthesis and analysis

Tolerances impose restrictions on the possible deviations of features from their nominal sizes/shapes. These variations of size/shape could be thought of as deviations of a set of generalized coordinates defined at some convenient point on a feature. Any tolerance specification for a feature imposes some kind of restrictions or constraints on its deviation parameters. These constraints, in general, define a bounded region in the deviation space. In this paper, a method has been presented for converting tolerance specifications as per maximum material condition (MMC)/least material condition (LMC)/regardless of feature size (RFS) material conditions for standard mating features (planar, cylindrical, and spherical) into a set of inequalities in a deviation space. Both virtual condition boundaries Virtual condition boundary: A constant boundary generated by the collective effects of a size feature's specified MMC or LMC material condition and the geometric tolerance for that material condition. (VCB) and tolerance zones are utilized for these mappings. The mapping procedures have been illustrated with an example. Note to Practitioners-This paper deals with methods to convert tolerance specification as per ASME Y14.5M into a set of generalized deviation of features and vice-versa. These are intermediate relationships that are required for use in deviation-based tolerance synthesis methods. In this work, different examples have been presented to show how different tolerance specifications (such as positional tolerance at maximum material condition (MMC), least material condition (LMC), etc.) applied to different features could be treated on a generalized basis for tolerancing of manufactured parts.     

Nature of V ions in SnO2: EPR and photoluminescence studies

SnO₂ and 5 at.% V doped SnO₂ samples were prepared by citrate-gel method. From Raman study on vanadium doped SnO₂, the existence of phase separated V₂O₅ clusters has been established. EPR study on the V doped sample clearly revealed the existence of V⁴⁺ ions, which are incorporated in SnO₂ lattice and the existence of conduction electrons with g = 1.993. For vanadium doped SnO₂ sample, there is a decrease in luminescence at 400 nm and an increase in activation energy of electrical conduction compared to undoped SnO₂, and this has been attributed to the decrease in oxygen vacancies brought about by the incorporation of V⁵⁺ in the SnO₂ lattice.     

Bi-functional NiO-ZnO nanocomposite: Synthesis,characterization, antibacterial and photo assisted degradation study

NiO–ZnO mixed metal oxide nanocomposite was synthesized via chemical homogeneous precipitation method. The synthesized nanocomposite was also characterized by XRD, FESEM with EDS, FTIR, and UV. XRD exhibit an average crystallite size of 29 nm. The elemental composition obtained from EDS shows a nearly equal concentration of Ni and Zn with an atomic ratio of Ni/Zn = 0.96. The particles of nanocomposite are highly stable throughout a wide range of pH. The DLS exhibit an average hydrodynamic particle size ~49 nm. The high pore diameter and pore volume of nanocomposite obtained from BET exhibited a high photocatalytic activity for the removal of methylene blue (MB) dye under UV light irradiation. The kinetics of photocatalytic reduction of MB followed the Langmuir isotherm model, suggesting homogeneous surface adsorption of MB on the surface of the nanocomposite. NiO-ZnO nanocomposite was also found to be an effective antibacterial agent against Gram positive bacteria (Staphylococcus aureus) and Gram negative bacteria (Escherichia coli). Colony forming unit plate counting method showed that 95% and 85% of S. aureus and E. coli respectively were killed by the nanocomposite. Also, this suggested that nanocomposite was more effective towards S. aureus than E. coli. Release of intracellular components was evident from FESEM image of nanocomposite-bacteria cell, cell integrity study, and cell permeability study. This included the release of electrolytes, nucleic acid, and proteins, ultimately leading to cell lysis.     

Analysis on down converting Sm3+-incorporated TiO2 mesoporous nanostructures for DSSC applications

Journal of Materials Science: Materials in Electronics - The Dye Sensitized Solar Cells (DSSCs) gaining scientific interest due to its immense property of increased photoelectric conversion...     

Light‐weight thermal insulating fly ash cenosphere ceramics

Light weight fly ash cenosphere (FAC) ceramic composites were developed by simple slip casting method. Thermal properties, Bulk density, Microstructure, flexural strength, and phase analysis of the FAC ceramic composites were measured. The results proved that the FAC have ability to lower bulk density and thermal conductivity effectively. The lowest thermal conductivity achieved for FAC ceramic composites (0.27 W/m.K) was further reduced 0.21 W/m.K by adding combustible additives ie activated charcoal and corn starch. The flexural strength, bulk density and thermal conductivity of FAC ceramic composites reduced consistently with an increase in FAC content. The maximum flexural strength of 13.45 MPa was achieved with 50% FAC and the minimum flexural strength of 4.07 MPa was obtained with 80% FAC. The open porosity increased from 35.51% to 43.76% and 38.19% with an addition of 15% activated charcoal and corn starch, respectively, when compared to no additives. The bulk density of 699, 619, and 675 kg/m³ was achieved with 80% FAC, 80% FAC with the addition of 15% activated charcoal and corn starch, respectively. The 80% FAC ceramic composite shows low thermal expansion coefficient 6.54 × 10^?6/°C at the temperature of 50°C then it varies between 3.7 and 5 × 10^?6/°C in the temperature range above 100°C. These results prove that the developed light weight FAC ceramic are excellent low‐cost thermal insulating materials.     

Droplet-based pyrosequencing using digital microfluidics

The feasibility of implementing pyrosequencing chemistry within droplets using electrowetting-based digital microfluidics is reported. An array of electrodes patterned on a printed-circuit board was used to control the formation, transportation, merging, mixing, and splitting of submicroliter-sized droplets contained within an oil-filled chamber. A three-enzyme pyrosequencing protocol was implemented in which individual droplets contained enzymes, deoxyribonucleotide triphosphates (dNTPs), and DNA templates. The DNA templates were anchored to magnetic beads which enabled them to be thoroughly washed between nucleotide additions. Reagents and protocols were optimized to maximize signal over background, linearity of response, cycle efficiency, and wash efficiency. As an initial demonstration of feasibility, a portion of a 229 bp Candida parapsilosis template was sequenced using both a de novo protocol and a resequencing protocol. The resequencing protocol generated over 60 bp of sequence with 100% sequence accuracy based on raw pyrogram levels. Excellent linearity was observed for all of the homopolymers (two, three, or four nucleotides) contained in the C. parapsilosis sequence. With improvements in microfluidic design it is expected that longer reads, higher throughput, and improved process integration (i.e., "sample-to-sequence" capability) could eventually be achieved using this low-cost platform.     

Synthesis of cobalt hexacyanoferrate nanoparticles and its hydrogen storage properties

In the present paper, we report hydrogen storage properties of cobalt hexacyanoferrate nanoparticles as a function of temperature. Cobalt hexacyanoferrate nanoparticles were synthesized by facile chemical precipitation method. The resulted compound forms FCC structure analogous to Prussian blue and is found to be stable up to 550 K. Presence of characteristic absorption bands in the range of 2000–2300 cm^?1 in IR spectra corresponds to the CN stretching frequency of Fe(III)CNCo(II) sequence and this confirms the formation of Prussian blue analogues. Hydrogen adsorption studies were performed at variable temperatures. The effect of precursor concentration on hydrogen storage property has been investigated and interestingly, with increase in cobalt precursor concentration, hydrogen storage capacity is found to decrease. This correlates well with openness of the crystal structure. To the best of our knowledge, this is the first report on hydrogen storage properties of cobalt hexacyanoferrate.     

Analysis of dipyridine dipyrrole based molecules for solar cell application using computational approach

Journal of Computational Electronics - In this work, six dipyridine dipyrrole (DPDP) derivatives are reported as π-conjugated, electron donor molecules used in BHJ solar cells. Density...