ABSTRACT
Liquid crystal elastomers (LCEs) exhibit significant viscoelasticity. Although the rate-dependent stress-strain relation of LCEs has already been widely observed, the effect of the intricate interplay of director rotation and network extension on the viscoelastic behavior of main-chain LCEs remains inadequately understood. In this study, we report real-time measurements of the stress, director rotation, and all strain components in main-chain nematic LCEs subjected to uniaxial tension both parallel and tilted to the initial directors at different loading rates and relaxation tests. We find that both network extension and director rotation play roles in viscoelasticity, and the characteristic relaxation time of the network extension is much larger than that of the director rotation. Interestingly, the gradual change of the director in a long-time relaxation indicates the director reorientation delay is not solely due to the viscous rotation of liquid crystals but also arises from its coupling with the highly viscous network. Additionally, significant rate-dependent shear strain occurs in LCEs under uniaxial tension, showing non-monotonic changes when the angle between the stretching and the initial director is large enough. Finally, a viscoelastic constitutive model, only considering the viscosity of the network by introducing multiplicative decomposition of the deformation gradient, is utilized to manifest the relation between rate-dependent macroscopic deformation and microscopic director rotation in LCEs.
ABSTRACT
BACKGROUND: Personalized body-worn alcohol dispensers may serve as an important tool for perioperative infection control, but the impact of these devices on the epidemiology of transmission of high-risk Enterococcus , Staphylococcus aureus , Klebsiella, Acinetobacter , Pseudomonas , and Enterobacter (ESKAPE) pathogens is unknown. We aimed to characterize the epidemiology of ESKAPE transmission in the pediatric anesthesia work area environment with and without a personalized body-worn alcohol dispenser. METHODS: This controlled before and after study included 40 pediatric patients enrolled over a 1-year study period. Two groups of operating room cases were compared: (1) operating room cases caring for patients with usual care (December 17, 2019, to August 25, 2020), and (2) operating room cases caring for patients with usual care plus the addition of a personalized, body-worn alcohol hand rub dispenser (September 30, 2020, to December 16, 2020). Operating rooms were randomly selected for observation of ESKAPE transmission in both groups. Device use was tracked via wireless technology and recorded in hourly hand decontamination events. RESULTS: Anesthesia providers used the alcohol dispenser 3.3 ± 2.1 times per hour. A total of 57 ESKAPE transmission events (29 treatment and 28 control) were identified. The personalized body-worn alcohol dispenser impacted ESKAPE transmission by increasing the contribution of provider hand contamination at case start (21/29 device versus 10/28 usual care; relative risk, [RR] 2.03; 99.17% confidence interval [CI], 1.025-5.27; P = .0066) and decreasing the contribution of environmental contamination at case end (3/29 device versus 12/28 usual care; RR, 0.24; 99.17% CI, 0.022-0.947; P = .0059). ESKAPE pathogen contamination involved 20% (8/40) of patient intravascular devices. There were 85% (34/40) of preoperative patient skin surfaces contaminated with ≥1 (1.78 ± 0.19 [standard deviation {SD}]) ESKAPE pathogens. CONCLUSIONS: A personalized body-worn alcohol dispenser can impact the epidemiology of ESKAPE transmission in the pediatric anesthesia work area environment. Improved preoperative patient decolonization and vascular care are indicated to address ESKAPE pathogens among pediatric anesthesia work area reservoirs.
ABSTRACT
ED-initiated addiction treatment holds promise for enhancing access to treatment for those with opioid use disorder (OUD). We present a literature review summarizing the evidence for buprenorphine induction in the ED including best practices for dosing, follow-up care, and reducing implementation barriers. A literature search of Pubmed, PsychInfo, and Embase identified articles studying OUD treatment in the ED published after 1980. Twenty-five studies were identified including eleven scientific abstracts. Multiple studies suggest that buprenorphine induction improves engagement in substance treatment up to 30 days after ED treatment. Many different induction protocols were presented, but no particular approach was best supported as criteria for induction and initial dosing vary widely. Similarly, transition of care models focused on either a "hub and spoke" model or "warm hand-offs" model, but no studies compared these approaches. Common barriers to implementing induction programs were provider inexperience, discomfort with addiction treatment, and limited time during the ED visit. No studies described the number of EDs offering induction. While ED buprenorphine induction is safe and enhances adherence to addiction treatment, uncertainty persists in how to best identify patients needing treatment, how to initiate buprenorphine, and how to enhance follow-up after ED-initiated treatment.
