The link between parents' perceptions of the school and their responses to school bullying: Variation by child characteristics and the forms of victimization.

A growing number of researchers encourage parents to notify the school when their children are bullied and work collaboratively with the school to resolve the situation. However, there is limited research on factors that are associated with parents' responses to their child's victimization. Using data from an online survey of 773 parents of victimized students enrolled in 93 schools (elementary, middle, and high), the current study employed structural equation modeling to examine the association between parents' perceptions of the school's climate and parents' responses to their child's victimization. The results indicated that the more favorable parents' perceptions of the climate were, the less likely they were to contact their child's school or talk to their child in response to the victimization. The parents' perception of the climate and response choice also varied as a function of the child's age and the form of bullying experienced. These findings suggest that parents' perceptions of the school are associated with their responses to their child's victimization. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

RAI: A High Throughput Routing Protocol for Multi-hop Multi-rate Ad hoc Networks

The advantages of using the multiple rates for wireless communications have been revealed in the recent years. To determine the appropriate rate and to make routing decision more precise, the communication nodes need the information from lower layer. Therefore, in this paper, a high throughput routing protocol using lower layer information for Multi-rate Ad-hoc Networks is proposed. We introduce a new routing metric named “Route Assessment Index” (RAI). The route with maximum RAI value is preferred to achieve the high throughput route, and to avoid the link bottleneck for reducing the packet drop rate. The chosen route also has a small number of hops. The routing protocol works in distributed manner, and correctness of the proposal is proven. The simulation results show that our new metric provides an accurate and efficient method for assessing and selecting the best route in Multi-rate Ad-hoc Networks.     

Optimization of the Scratch Test for specific coating designs

The proper design of wear resistant coatings applied to cutting tools comprises the optimization of the mechanical properties (Young's modulus, yield strength, adhesion, intrinsic stresses, fracture, fretting etc.) of the coating-tool system. The goal is to find material and structural solutions which keep the resulting stress-strain field under typical application conditions below the stability limits of the system. Based on nanoindentation measurements obtained from the coating-tool system which should be optimized, a scratch test is dimensioned with respect to load range and indenter geometry. The measured data from this “Physical Scratch Test” are used to simulate spatial stress profiles and to calculate the von Mises stress characteristics and the maximum normal stresses in the scratch direction. In a further step, the simulations are used to suggest scratch parameters for a “Fine Tuned Scratch Test” which increase the sensitivity of the test for specific depth regions in the coating-tool architecture and allow improved and more sensitive investigations of critical interfaces, transition layers and surface-near substrate regions. The tests were performed at PVD coated inserts (nitrides and oxides) and compared with the results obtained from cutting tests.     

The structure of a linear chip firing game and related models

In this paper, we study the dynamics of sand grains falling in sand piles. Usually sand piles are characterized by a decreasing integer partition and grain moves are described in terms of transitions between such partitions. We study here four main transition rules. The worst classical one, introduced by Brylawski (Discrete Math. 6 (1973) 201) induces a lattice structure L_B(n) (called dominance ordering) between decreasing partitions of a given integer n. We prove that a more restrictive transition rule, called SPM rule, induces a natural partition of L_B(n) in suborders, each one is associated to a fixed point for the SPM rule. In the second part, we extend the SPM rule in a natural way and obtain a model called Linear Chip Firing Game (Theoret. Comput. Sci. 115 (1993) 321). We prove that this new model has interesting properties: the induced order is a lattice, a natural greedoid can be associated to the model and it also defines a strongly convergent game. In the last section, we generalize the SPM rule in another way and obtain other lattice structure parametrized by some θ, denoted by L(n,θ), which form a decreasing sequence of lattices when θ varies in [−n+2,n]. For each θ, we characterize the fixed point of L(n,θ) and give the value of its maximal sized chain's length. We also note that L(n,−n+2) is the lattice of all compositions of n.     

The chemical and structural origin of efficient p-type doping in P3HT

We investigate the chemical and structural properties of solution-processed thin films of P3HT blended with p-type dopant F4TCNQ. The maximum in-plane electrical conductivity of doped films is observed at a molar doping fraction of 0.17, in agreement with the binding mechanism of F4TCNQ:P3HT complexes. Through the use of X-ray diffraction, a previously unreported crystalline phase is observed for P3HT films doped above a critical threshold concentration. This crystalline phase involves the incorporation of F4TCNQ molecules into ordered polymer regions and ultimately improves charge dissociation, leading to higher carrier density in thin film. Finally, optical absorption and X-ray diffraction reveal that the chemical state of P3HT in solution has a dramatic impact on the electrical and structural properties of the blended films.     

Modified Fluoroquinolones as Antimicrobial Compounds Targeting Chlamydia trachomatis

Chlamydia trachomatis causes the most common sexually transmitted bacterial infection and trachoma, an eye infection. Untreated infections can lead to sequelae, such as infertility and ectopic pregnancy in women and blindness. We previously enhanced the antichlamydial activity of the fluoroquinolone ciprofloxacin by grafting a metal chelating moiety onto it. In the present study, we pursued this pharmacomodulation and obtained nanomolar active molecules (EC₅₀) against this pathogen. This gain in activity prompted us to evaluate the antibacterial activity of this family of molecules against other pathogenic bacteria, such as Neisseria gonorrhoeae and bacteria from the ESKAPE group. The results show that the novel molecules have selectively improved activity against C. trachomatis and demonstrate how the antichlamydial effect of fluoroquinolones can be enhanced.     

Generalized Approach towards Secretion-Based Protein Production via Neutralization of Secretion-Preventing Cationic Substrate Residues

Many heterologous proteins can be secreted by bacterial ATP-binding cassette (ABC) transporters, provided that they are fused with the C-terminal signal sequence, but some proteins are not secretable even though they carry the right signal sequence. The invention of a method to secrete these non-secretable proteins would be valuable both for understanding the secretory physiology of ABC transporters and for industrial applications. Herein, we postulate that cationic “supercharged” regions within the target substrate protein block the secretion by ABC transporters. We also suggest that the secretion of such substrate proteins can be rescued by neutralizing those cationic supercharged regions via structure-preserving point mutageneses. Surface-protruding, non-structural cationic amino acids within the cationic supercharged regions were replaced by anionic or neutral hydrophilic amino acids, reducing the cationic charge density. The examples of rescued secretions we provide include the spike protein of SARS-CoV-2, glutathione-S-transferase, streptavidin, lipase, tyrosinase, cutinase, growth factors, etc. In summary, our study provides a method to predict the secretability and a tool to rescue the secretion by correcting the secretion-blocking regions, making a significant step in understanding the physiological properties of ABC transporter-dependent protein secretion and laying the foundation for the development of a secretion-based protein-producing platform.     

A novel active‐clamp zero‐voltage‐switching buck‐boost converter

An active‐clamp zero‐voltage‐switching (ZVS) buck‐boost converter is proposed in this paper to improve the performance of converter in light load condition. By employing a small resonant inductor, the ZVS range of switches could be adjusted to very light load condition. Moreover, 2 clamping capacitors are added in the converter to eliminate the voltage spike on the switches during transition. The operating principle of the proposed converter is analyzed, and the optimal design guide for full range ZVS is also provided. A 60‐W output prototype is experimentally built and tested in laboratory to verify the feasibility of proposed converter. The measured results show the critical ZVS operation of power switches at 1 and 0.7‐W output power for buck and boost mode, respectively. The peak conversion efficiency is up to 92.3%.     

Density-controllable growth of SnO2 nanowire junction-bridging across electrode for low-temperature NO2 gas detection

The junction-bridging structure of metal oxide nanowires (NWs) improves gas-sensing properties. In this study, an on-chip growth method was used to fabricate gas sensors, it easily and effectively controls NW junctions. SnO₂ NWs were synthesized by thermal evaporation at 800 °C with tin powder as the source. The density of the NW junctions was controlled by changing the mass of the source material. A source material with large mass yielded high-density NW junctions. With electrode spacing of 20 μm, NW junctions were formed from the source material of larger than 2 mg. Gas sensing results revealed that the junction sensors exhibited a good response to NO₂ gas at a concentration of 1–10 ppm. The sensors exhibited a good response to NO₂ gas at low temperature of up to 100 °C and short response–recovery time (~20 s). The sensors also had good selectivity to NO₂ gas. The response (R _gas /R _air) to 1 ppm NO₂ was as high as 22 at 100 °C, whereas the cross gas responses (R _air /R _gas) to 10 ppm CO, 10 ppm H₂S, 100 ppm C₂H₅OH, and 100 ppm NH₃ were negligible (1.1–1.3).