Photoswitchable optoelectronic properties of 2D MoSe2/diarylethene hybrid structures.

The ability to modulate optical and electrical properties of two-dimensional (2D) semiconductors has sparked considerable interest in transition metal dichalcogenides (TMDs). Herein, we introduce a facile strategy for modulating optoelectronic properties of monolayer MoSe2 with external light. Photochromic diarylethene (DAE) molecules formed a 2-nm-thick uniform layer on MoSe2, switching between its closed- and open-form isomers under UV and visible irradiation, respectively. We have discovered that the closed DAE conformation under UV has its lowest unoccupied molecular orbital energy level lower than the conduction band minimum of MoSe2, which facilitates photoinduced charge separation at the hybrid interface and quenches photoluminescence (PL) from monolayer flakes. In contrast, open isomers under visible light prevent photoexcited electron transfer from MoSe2 to DAE, thus retaining PL emission properties. Alternating UV and visible light repeatedly show a dynamic modulation of optoelectronic signatures of MoSe2. Conductive atomic force microscopy and Kelvin probe force microscopy also reveal an increase in conductivity and work function of MoSe2/DAE with photoswitched closed-form DAE. These results may open new opportunities for designing new phototransistors and other 2D optoelectronic devices.

Perspective: The current state of Cre driver mouse lines in skeletal research: Challenges and opportunities.

The Cre/Lox system has revolutionized the ability of biomedical researchers to ask very specific questions about the function of individual genes in specific cell types at specific times during development and/or disease progression in a variety of animal models. This is true in the skeletal biology field, and numerous Cre driver lines have been created to foster conditional gene manipulation in specific subpopulations of bone cells. However, as our ability to scrutinize these models increases, an increasing number of issues have been identified with most driver lines. All existing skeletal Cre mouse models exhibit problems in one or more of the following three areas: (1) cell type specificity-avoiding Cre expression in unintended cell types; (2) Cre inducibility-improving the dynamic range for Cre in inducible models (negligible Cre activity before induction and high Cre activity after induction); and (3) Cre toxicity-reducing the unwanted biological effects of Cre (beyond loxP recombination) on cellular processes and tissue health. These issues are hampering progress in understanding the biology of skeletal disease and aging, and consequently, identification of reliable therapeutic opportunities. Skeletal Cre models have not advanced technologically in decades despite the availability of improved tools, including multi-promoter-driven expression of permissive or fragmented recombinases, new dimerization systems, and alternative forms of recombinases and DNA sequence targets. We review the current state of skeletal Cre driver lines, and highlight some of the successes, failures, and opportunities to improve fidelity in the skeleton, based on successes pioneered in other areas of biomedical science.

Polytraumatized patient lower extremity nonunion development: Raw data.

In this article we report data collected to evaluate the pathomechanistic effect of acute anaerobic metabolism in the polytraumatized patient and its subsequent effect on fracture nonunion; see "Base Deficit ≥6 within 24 Hours of Injury is a Risk Factor for Fracture Nonunion in the Polytraumatized Patient" (Sardesai et al., 2021) [1]. Data was collected on patients age ≥16 with an Injury Severity Score (ISS) >16 that presented between 2013-2018 who sustained a fracture of the tibia or femur distal to the femoral neck. Patients presenting to our institution greater than 24 hours post-injury and those with less than three months follow-up were excluded. Medical charts were reviewed to collect patient demographic information and known nonunion risk-factors, including smoking, alcohol use, and diabetes. In addition, detailed injury characteristics to quantify injury magnitude including ISS, Glasgow Coma Scale (GCS) at admission, and ICU length of stay were recorded. ISS values were obtained from our institutional trauma database where they are entered by individuals trained in ISS calculations. Associated fracture-related features including fracture location, soft-tissue injury (open vs. closed fracture), vascular injury, and compartment syndrome were recorded. Finally, vital signs, base deficit (BD), and blood transfusions over 24 hours from admission were recorded. We routinely measure BD and less consistently measure serum lactate in trauma patients at the time of presentation or during resuscitation. BD values are automatically produced by our laboratory with any arterial blood gas order, and we recorded BD values from the medical record. Clinical notes and radiographs were reviewed to confirm fracture union versus nonunion and assess for deep infection at the fracture site. Patients were categorized as having a deep infection if they were treated operatively for the infection prior to fracture healing or classification as a nonunion. Nonunion was defined by failure of progressive healing on sequential radiographs and/or surgical treatment for nonunion repair at least six months post-injury.

Base Deficit ≥ 6 within 24 h of Injury is a risk factor for fracture nonunion in the polytraumatized patient.

BACKGROUND: Polytrauma patients are at risk for fracture nonunion, but the reasons are poorly understood. Increased base deficit (BD) is associated with hypovolemic shock. Although shock delays bone healing in animal models, there have been no clinical studies evaluating the impact of BD on nonunion risk. MATERIALS AND METHODS: Patients age ≥ 16 with injury severity score > 16 that presented to an academic Level One trauma center with an operative femur or tibia fracture were reviewed. Clinical notes and radiographs were assessed to determine fracture healing status. Patient demographics, injury characteristics, BD, and number of packed red blood cell transfusions were recorded. Bivariate and multivariate analyses of multiple risk factors associated with nonunion were conducted to investigate the association of BD with nonunion. RESULTS: The union group was comprised of 243 fractures; there were 36 fractures in the nonunion group. The following predictors were associated with nonunion: smoking (p = 0.009), alcohol use (p < 0.001), open fracture (p < 0.001), and treatment for deep infection at fracture site (p = 0.016). Additionally, worst BD over 24 h ≥ 6 (p = 0.031) was significant for nonunion development. A multivariate logistic regression analysis revealed worst BD ≥6 over 24 h remained significantly associated with the development of nonunion (odds ratio 3.02, p = 0.011) when adjusting for other risk factors. CONCLUSIONS: A BD ≥ 6 within 24 h of admission was associated with a significantly increased risk of developing lower extremity fracture nonunion in polytrauma patients, even after adjusting for multiple other risk factors. Acute post-traumatic acidosis may have effects on long-term fracture healing.

Is Physical Activity Associated With Loneliness or Social Isolation in Older Adults? Results of a Longitudinal Analysis Using the Irish Longitudinal Study on Ageing.

Social relationships are central to the health and well-being of older adults. Evidence exploring the association of physical activity (PA) with social isolation and loneliness is limited. This study uses a path analysis to investigate the longitudinal association between loneliness and social isolation with PA using the Irish Longitudinal Study on Ageing. Higher levels of social isolation measured using the Berkman-Syme Social Network Index were directly and indirectly associated with lower levels of walking, moderate PA, and vigorous PA over 6 years. Additionally, higher levels of walking were associated with lower levels of loneliness measured using a modified version of the University of California, Los Angeles loneliness scale over a 3-year period. Future interventions should target individuals who are more socially isolated and explore the effects of different types of PA on loneliness over time.