Visually-guided protein crystal manipulation using micromachined silicon tools

We present a system for protein crystal micro-manipulation with focus on automated crystal mounting for the purposes of X-ray data collection. The system features a set of newly designed micropositioner end-effectors we call microshovels which address some limitations of the traditional cryogenic loops. We have used micro-electrical mechanical system (MEMS) techniques to design and manufacture various shapes and quantities of microshovels. Visual feedback from a camera mounted on the microscope is used to control the micropositioner as it lowers a microshovel into the liquid containing the crystals and approaches a selected crystal for pickup. We present experimental results that illustrate the applicability of our approach

Visually-guided protein crystal manipulation using micromachined silicon tools

We present a system for protein crystal micro-manipulation with focus on automated crystal mounting for the purposes of X-ray data collection. The system features a set of newly designed micropositioner end-effectors we call microshovels which address some limitations of the traditional cryogenic loops. We have used micro-electrical mechanical system (MEMS) techniques to design and manufacture various shapes and quantities of microshovels. Visual feedback from a camera mounted on the microscope is used to control the micropositioner as it lowers a microshovel into the liquid containing the crystals and approaches a selected crystal for pickup. We present experimental results that illustrate the applicability of our approach

Highly Concentrated LiTFSI-EC Electrolytes for Lithium Metal Batteries

Concentrated electrolytes have the potential to increase the stability for batteries with lithium metal anodes. In this study, liquid electrolytes were created by mixing ethylene carbonate (EC), a solid at room temperature, with a high concentration of LiTFSI salt. The binary LiTFSI-EC highly concentrated electrolytes have the benefit of extremely low volatility as compared to conventional organic electrolytes and also allow for cycling vs Li metal anodes. Using a LiTFSI-EC electrolyte with molar ratio 1:6, the Coulombic efficiency for Li plating/stripping on Cu is 97% at a current density of 1 mA cm-2 with a 2 mAh cm-2 capacity, pointing to a practically useful performance. In a full cell setup using a commercial LiFePO4 (LFP) cathode, the efficiency is maintained, proving compatibility. In comparison to other carbonate-based electrolytes, there is less accumulation of decomposition products on the surface of a cycled Li film, which in part explains the improved cycle life. In all, this electrolyte system shows promise in terms of electrochemical stability and may allow for safe Li metal batteries due to the inherent physical stability.\ua0\ua9 2019 American Chemical Society

Observed Reductions in School Bullying, Nonbullying Aggression, and Destructive Bystander Behavior: A Longitudinal Evaluation

This study was a longitudinal extension of a random control trial of the Steps to Respect antibullying program. Students in Grades 3–5 were surveyed (n = 624) and observed on the playground (n = 360). Growth curve models of intervention students showed 2-year declines in playground bullying, victimization, nonbullying aggression, destructive bystander, and argumentative behavior. Grade-equivalent contrasts indicated group differences in all problem behaviors. Problem behaviors in the control group increased or remained stable across grade. Intervention group students reported less difficulty responding assertively to bullying compared with control students. Within both groups, older students perceived themselves to be more aggressive and less frequently victimized than younger students. Methodological issues posed by inconsistencies between self-reported and observed behavior are discussed

Effects of a School-Based Social-Emotional Competence Program: Linking Children\u27s Goals, Attributions, and Behaviors

This study examined the effects of the Second Step social–emotional learning program and addressed the relations between social cognitions and prosocial and antisocial behavior. Children (N = 1,253) in intervention and control groups were assessed by teacher ratings, self report, and observation in two conflict situations. Intervention children were more likely to prefer prosocial goals and give egalitarian reasons for satisfaction than control children. Intervention children also required less adult intervention, and behaved less aggressively and (among girls) more cooperatively. Teacher ratings of social behavior showed improvement over time. Individual and dyadic behavior varied as a function of goals, hostile attributions, and attitude concordance within dyads. Findings are discussed with respect to social-cognitive models of aggression and prosocial behavior

A Microrobotic System For Protein Streak Seeding

We present a microrobotic system for protein crystal micromanipulation tasks. The focus in this report is on a task called streak seeding, which is used by crystallographers to entice certain protein crystals to grow. Our system features a set of custom designed micropositioner end-effectors we call microshovels to replace traditional tools used by crystallographers for this task. We have used micro-electrical mechanical system (MEMS) techniques to design and manufacture various shapes and quantities of microshovels. Visual feedback from a camera mounted on the microscope is used to control the micropositioner as it lowers a microshovel into the liquid containing the crystals for poking and streaking. We present experimental results that illustrate the applicability of our approach

Walking the Talk in Bullying Prevention: Teacher Implementation Variables Related to Initial Impact of the \u27Steps to Respect\u27 Program

This study examined relationships between teacher implementation of a comprehensive bullying prevention program and student outcomes. Implementation in third- through sixth-grade classrooms (N = 36) was measured by observation and teacher report. Student outcomes were measured by student surveys and teacher ratings of peer social skills (N = 549) and observations of playground behaviors (n = 298). Multilevel modeling showed that teacher coaching of students involved in bullying was associated with less observed victimization and destructive bystander behavior among students engaged in these problems at pretest, and less observed aggression among fifth- and sixth-grade students. Support for skill generalization related to reductions in observed aggression and victimization among older students. Adherence to lessons was associated with higher ratings of peer social skills. Quality of lesson instruction corresponded to greater self-reported victimization, as well as more perceived difficulty responding assertively to bullying. Implications for school-based practice and future research directions are discussed

Construction and analysis of causally dynamic hybrid bond graphs

Engineering systems are frequently abstracted to models with discontinuous behaviour (such as a switch or contact), and a hybrid model is one which contains continuous and discontinuous behaviours. Bond graphs are an established physical modelling method, but there are several methods for constructing switched or ‘hybrid’ bond graphs, developed for either qualitative ‘structural’ analysis or efficient numerical simulation of engineering systems. This article proposes a general hybrid bond graph suitable for both. The controlled junction is adopted as an intuitive way of modelling a discontinuity in the model structure. This element gives rise to ‘dynamic causality’ that is facilitated by a new bond graph notation. From this model, the junction structure and state equations are derived and compared to those obtained by existing methods. The proposed model includes all possible modes of operation and can be represented by a single set of equations. The controlled junctions manifest as Boolean variables in the matrices of coefficients. The method is more compact and intuitive than existing methods and dispenses with the need to derive various modes of operation from a given reference representation. Hence, a method has been developed, which can reach common usage and form a platform for further study