Liquid lasing from solutions of ligand-engineered semiconductor nanocrystals.

Semiconductor nanocrystals (NCs) can function as efficient gain materials with chemical versatility because of their surface ligands. Because the properties of NCs in solution are sensitive to ligand-environment interactions, local chemical changes can result in changes in the optical response. However, amplification of the optical response is technically challenging because of colloidal instability at NC concentrations needed for sufficient gain to overcome losses. This paper demonstrates liquid lasing from plasmonic lattice cavities integrated with ligand-engineered CdZnS/ZnS NCs dispersed in toluene and water. By taking advantage of calcium ion-induced aggregation of NCs in aqueous solutions, we show how lasing threshold can be used as a transduction signal for ion detection. Our work highlights how NC solutions and plasmonic lattices with open cavity architectures can serve as a biosensing platform for lab-on-chip devices.

The process of telepractice implementation during the COVID-19 pandemic: a narrative inquiry of preschool speech-language pathologists and assistants from one center in Canada.

BACKGROUND: Many professional services were pressed to adopt telepractice in response to the global coronavirus SARS-CoV-2 (COVID-19) pandemic. The need to adopt a new service delivery approach quickly created different implementation challenges. This study explored the lived experiences of frontline clinicians who successfully transitioned their in-person speech-language therapy services to telepractice through an implementation science lens. METHODS: The study was conducted in partnership with one publicly funded program in Ontario, Canada that offers services to preschoolers with speech, language and communication disorders. Sixteen frontline speech-language pathologists and assistants at this organization shared their lived experience transitioning to telepractice during the pandemic during videoconference interviews. A narrative inquiry approach was used to analyze interview transcripts to identify the processes (or steps) this program took to implement telepractice and to understand the facilitators and barriers to telepractice implementation during the pandemic. RESULTS: The following six stages were identified from clinicians' narratives: abrupt lockdown; weeks of uncertainty; telepractice emerged as an option; preparation for telepractice; telepractice trials; and finally, full implementation of telepractice. The stages of events offered significant insights into how government public health measures influenced clinicians' decisions and their processes of adopting telepractice. In terms of barriers, clinicians reported a lack of knowledge, skills and experience with telepractice and a lack of technological support. The organization's learning climate and team approach to transitioning services were identified as the main facilitator of implementation. CONCLUSIONS: Findings suggest a need for better coordination of public health measures and professional services, which would have eased clinicians' stress and facilitated an earlier transition to telepractice. Fostering an organization's learning climate may improve organization's resilience in response to emergency situations.

Single-Leg Squat Delicacies-The Position of the Nonstance Limb is an Important Consideration.

Context: The single-leg squat task is often used as a rehabilitative exercise or as a screening tool for the functional movement of the lower limb. Objective: To establish the effect of 3 different positions of the nonstance leg on 3-dimensional kinematics, muscle activity, and center of mass displacement during a single-leg squat. Design: Within-subjects, repeated-measures design. Setting: Movement analysis laboratory. Participants: A total of 10 participants, aged 28.2 (4.42) years performed 3 squats to 60° of knee flexion with the nonstance (1) hip at 90° flexion and knee at 90° flexion, (2) hip at 30° flexion with the knee fully extended, or (3) hip in neutral/0° and the knee flexed to 90°. Main Outcome Measures: Trunk, hip, knee and ankle joint angles, and center of mass displacement were recorded with inertial sensors while muscle activity was captured through wireless electromyography. Results: Most trunk flexion (21.38° [18.43°]) occurred with the nonstance hip at 90° and most flexion of the stance hip (23.10° [6.60°]) occurred with the nonstance hip at 0°. Biceps femoris activity in the 90° squat was 40% more than in the 0° squat, whereas rectus femoris activity in the 0° squat was 29% more than in the 90° squat. Conclusion: The position of the nonstance limb should be standardized when the single-leg squat is used for assessment and be adapted to the aim when used in rehabilitation.

HIV-related stigma and social capital in South Africa.

Few studies have considered the relationship between social capital and stigmatizing attitudes. The aim of this study is to assess the relationship between HIV stigmatizing attitudes and individual perceptions of social capital in South Africa. The study surveyed 619 community members to assess whether social capital predicted personal and attributed HIV stigmatizing attitudes. Personal stigma was defined as the individual's own attitude toward people with HIV and attributed stigma were those attitudes that the individual perceived as existing in their communities. Results showed that social capital components significantly predicted personal and attributed stigma above and beyond demographic covariates and whether the participant knew someone with HIV. Individual social capital components of empowerment, trust, and group membership related to personal stigma; and safety, trust, and homogeneity of residential area related to attributed stigma.

Synthesis of the pyrrolidinone core of KSM-2690 B.

[reaction: see text] The first synthesis of the pyrrolidinone core of the polyene beta-lactone antibiotic KSM-2690 B is described. An ammonia-free Birch reductive aldol reaction utilizing acetaldehyde is one of the key steps, together with a ruthenium-catalyzed alkene isomerization reaction.

Relations between social support, appraisal and coping and both positive and negative outcomes in young carers.

This study examined a stress/coping model of adjustment in early caregiving. It was hypothesized that better adjustment would be related to higher social support and approach coping, and lower stress appraisals and avoidant coping. One hundred young carers aged 10-25 years completed questionnaires. Predictors included choice in caregiving, social support, stress appraisal and coping. Dependent variables were global distress and positive outcomes (life satisfaction, positive affect, benefits). Correlations supported all hypothesized relations between the stress/coping predictors and adjustment outcomes. Regression analyses showed social support as the strongest predictor of adjustment, whereas coping and choice in caregiving emerged as weaker predictors and stress appraisal was unrelated to adjustment. The stress/coping framework and findings have the potential to inform interventions designed to promote well-being in young carers.

The ammonia-free partial reduction of substituted pyridinium salts.

This paper reports a study into the partial reduction of N-alkylpyridinium salts together with subsequent elaboration of the intermediates thus produced. Activation of a pyridinium salt by placing an ester group at C-2, allows the addition of two electrons to give a synthetically versatile enolate intermediate which can be trapped with a variety of electrophiles. Furthermore, the presence of a 4-methoxy substituent on the pyridine nucleus enhances the stability of the enolate reaction products, and hydrolysis in situ gives stable dihydropyridone derivatives in good yields. These versatile compounds are prepared in just three steps from picolinic acid and can be derivatised at any position on the ring, including nitrogen when a p-methoxybenzyl group is used as the N-activating group on the pyridinium salt. This publication describes our exploration of the optimum reducing conditions, the most appropriate N-alkyl protecting group, as well as the best position on the ring for the methoxy group. Electrochemical techniques which mimic the synthetic reducing conditions are utilised and they give clear support for our proposed mechanism of reduction in which there is a stepwise addition of two electrons to the heterocycle, mediated by di-tert-butylbiphenyl (DBB). Moreover, there is a correlation between the viability of reduction of a given heterocycle under synthetic conditions and its electrochemical response; this offers the potential for use of electrochemistry in predicting the outcome of such reactions.

Epidemiologic studies of PCB congener profiles in North American fish consuming populations.

Long range atmospheric and stream transport and oceanic currents drive the ecologic process of PCB deposition in the abiotic environment. In contrast short range transport via bioaccumulation-biomagnification up the food chain determines PCB congener profiles and concentrations and their adverse effects in biological organisms. Two research approaches to congeners, with potential to associate specific adverse human health effects with PCB concentrations in indigenous small populations, are summarized in this study. The field epidemiological approach includes giving questionnaires to target population groups in conjunction with sampling for PCBs (and selected persistent organic pollutants and metals), in foods purchased or hunted and collected by Inuit peoples. Direct determination of contaminant levels in food sources and among individuals in selected comparative subpopulations is also presented.