Multifunctional temperature-responsive polymers as advanced biomaterials and beyond

The versatility and applicability of thermoresponsive polymeric systems have led to great interest and a multitude of publications. Of particular significance, multifunctional poly(N-isopropylacrylamide) (PNIPAAm) systems based on PNIPAAm copolymerized with various functional comonomers or based on PNIPAAm combined with nanomaterials exhibiting unique properties. These multifunctional PNIPAAm systems have revolutionized several biomedical fields such as controlled drug delivery, tissue engineering, self-healing materials, and beyond (e.g., environmental treatment applications). Here, we review these multifunctional PNIPAAm-based systems with various cofunctionalities, as well as highlight their unique applications. For instance, addition of hydrophilic or hydrophobic comonomers can allow for polymer lower critical solution temperature modification, which is especially helpful for physiological applications. Natural comonomers with desirable functionalities have also drawn significant attention as pressure surmounts to develop greener, more sustainable materials. Typically, these systems also tend to be more biocompatible and biodegradable and can be advantageous for use in biopharmaceutical and environmental applications. PNIPAAm-based polymeric nanocomposites are reviewed as well, where incorporation of inorganic or carbon nanomaterials creates synergistic systems that tend to be more robust and widely applicable than the individual components. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48770.     

Recent Progress in Photocatalysis Mediated by Colloidal II-VI Nanocrystals

The use of photoexcited electrons and holes in semiconductor nanocrystals as reduction and oxidation reagents is an intriguing way of harvesting photon energy to drive chemical reactions. This review focuses on recent research efforts to understand and control the photocatalytic processes mediated by colloidal II-VI nanocrystalline materials, such as cadmium and zinc chalcogenides. First, we highlight how nanocrystal properties govern the rates and efficiencies of charge-transfer processes relevant to photocatalysis. We then describe the use of nanocrystal catalyst heterostructures for fuel-forming reactions, most commonly H₂ generation. Finally, we review the use of nanocrystal photocatalysis as a synthetic tool for metal–semiconductor nano-heterostructures.     

Pseudoelastic behaviour of a natural material is achieved via reversible changes in protein backbone conformation

The egg capsules of marine prosobranch gastropods, commonly know as whelks, function as a protective encapsulant for whelk embryos in wave-swept marine environments. The proteinaceous sheets comprising the wall of whelk egg capsules (WEC) exhibit long-range reversible extensibility with a hysteresis of up to 50 per cent, previously suggested to result from reversible changes in the structure of the constituent protein building blocks. Here, we further investigate the structural changes of the WEC biopolymer at various hierarchical levels using several different time-resolved in situ approaches. We find strong evidence in these biological polymers for a strain-induced reversible transition from an ordered conformational phase to a largely disordered one that leads to the characteristic reversible hysteretic behaviour, which is reminiscent of the pseudoelastic behaviour in some metallic alloys. On the basis of these results, we generate a simple numerical model incorporating a worm-like chain equation to explain the phase transition behaviour of the WEC at the molecular level.     

Pilot-scale in situ bioremedation of uranium in a highly contaminated aquifer. 2. Reduction of u(VI) and geochemical control of u(VI) bioavailability

In situ microbial reduction of soluble U(VI) to sparingly soluble U(IV) was evaluated at the site of the former S-3 Ponds in Area 3 of the U.S. Department of Energy Natural and Accelerated Bioremediation Research Field Research Center, Oak Ridge, TN. After establishing conditions favorable for bioremediation (Wu, et al. Environ. Sci. Technol. 2006, 40, 3988-3995), intermittent additions of ethanol were initiated within the conditioned inner loop of a nested well recirculation system. These additions initially stimulated denitrification of matrix-entrapped nitrate, but after 2 months, aqueous U levels fell from 5 to approximately 1 microM and sulfate reduction ensued. Continued additions sustained U(VI) reduction over 13 months. X-ray near-edge absorption spectroscopy (XANES) confirmed U(VI) reduction to U(IV) within the inner loop wells, with up to 51%, 35%, and 28% solid-phase U(IV) in sediment samples from the injection well, a monitoring well, and the extraction well, respectively. Microbial analyses confirmed the presence of denitrifying, sulfate-reducing, and iron-reducing bacteria in groundwater and sediments. System pH was generally maintained at less than 6.2 with low bicarbonate level (0.75-1.5 mM) and residual sulfate to suppress methanogenesis and minimize uranium mobilization. The bioavailability of sorbed U(VI) was manipulated by addition of low-level carbonate (< 5 mM) followed by ethanol (1-1.5 mM). Addition of low levels of carbonate increased the concentration of aqueous U, indicating an increased rate of U desorption due to formation of uranyl carbonate complexes. Upon ethanol addition, aqueous U(VI) levels fell, indicating that the rate of microbial reduction exceeded the rate of desorption. Sulfate levels simultaneously decreased, with a corresponding increase in sulfide. When ethanol addition ended but carbonate addition continued, soluble U levels increased, indicating faster desorption than reduction. When bicarbonate addition stopped, aqueous U levels decreased, indicating adsorption to sediments. Changes in the sequence of carbonate and ethanol addition confirmed that carbonate-controlled desorption increased bioavailability of U(VI) for reduction.     

Development of a method for evaluating accessibility of medical equipment for patients with disabilities

Objective

The purpose of this study was to develop a method for evaluating accessibility of medical equipment for patients with disabilities.

Methods

The researchers reviewed videotapes of patient-participants with various physical and sensory disabilities using different types of medical equipment. For each of 11 videotapes, four observers independently identified and documented access and safety barriers, such as physical, sensory, cognitive, and environmental barriers. Inter-observer variability for identifying barrier presence was assessed with kappa statistics for pairs of observers.

Results

A list of 10 access and safety barriers was developed through an iterative consensus process, which identified design features of medical equipment that presented difficulties for participants with disabilities. The list is useful for identifying and categorizing accessibility problems found in equipment. While reliability of barrier identification was substantial or moderate for some barriers, reconciliation of barrier events identified by multiple video observers is recommended for optimal results.     

Anorexia nervosa and autism spectrum disorders: Guided investigation of social cognitive endophenotypes.

Death by suicide occurs in a disproportionate percentage of individuals with anorexia nervosa (AN), with a standardized mortality ratio indicating a 57-fold greater risk of death from suicide relative to an age-matched cohort. Longitudinal studies indicate impaired social functioning increases risk for fatal outcomes, while social impairment persists following recovery. Study of social cognition in AN may elucidate impaired processes that may influence therapeutic efficacy. Symptoms of autism spectrum disorders (ASD) are overrepresented in those who evidence a chronic course. Relative to that in AN, social information processing in ASD is well characterized and may inform systematic study in AN. This article (a) reviews impaired interpersonal processes in AN, (b) compares the phenotype of AN with that of ASD, (c) highlights deficits of social cognitive disturbance in ASD relative to AN, and (d) proposes a new framework to understand the interaction of individuals with AN with their social context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Back to basics: The importance of focus selection.

Examines the importance of selecting a therapeutic focus when teaching the introductory course in brief insight-oriented psychotherapy to psychiatric residents. The initial attention required toward the selection of a focus, and adherence to this central theme during treatment, are the essential features of the brief therapeutic technique. Case material from a 68-yr-old man provided by a resident illustrates the process of finding a therapeutic focus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Not Now! Supporting interruption management by indicating the modality and urgency of pending tasks

Operators in complex event-driven domains must coordinate competing attentional demands in the form of multiple tasks and interactions. This study examined the extent to which this requirement can be supported more effectively through informative interruption cueing (in this case, partial information about the nature of pending tasks). The 48 participants performed a visually demanding air traffic control (ATC) task. They were randomly assigned to 1 of 3 experimental groups that differed in the availability of information (not available, available upon request, available automatically) about the urgency and modality of pending interruption tasks. Within-subject variables included ATC-related workload and the modality, frequency, and priority of interruption tasks. The results show that advance knowledge about the nature of pending tasks led participants to delay visual interruption tasks the longest, which allowed them to avoid intramodal interference and scanning costs associated with performing these tasks concurrently with ATC tasks. The 3 experimental groups did not differ significantly in terms of their interruption task performance; however, the group that automatically received task-related information showed better ATC performance, thus experiencing a net performance gain. Actual or potential applications of this research include the design of interfaces in support of attention and interruption management in a wide range of event-driven environments.     

Fibrinogen Replacement Therapy for Traumatic Coagulopathy: Does the Fibrinogen Source Matter?

Fibrinogen is the first coagulation protein to reach critically low levels during traumatic haemorrhage. There have been no differential effects on clinical outcomes between the two main sources of fibrinogen replacement: cryoprecipitate and fibrinogen concentrate (Fg-C). However, the constituents of these sources are very different. The aim of this study was to determine whether these give rise to any differences in clot stability that may occur during trauma haemorrhage. Fibrinogen deficient plasma (FDP) was spiked with fibrinogen from cryoprecipitate or Fg-C. A panel of coagulation factors, rotational thromboelastography (ROTEM), thrombin generation (TG), clot lysis and confocal microscopy were performed to measure clot strength and stability. Increasing concentrations of fibrinogen from Fg-C or cryoprecipitate added to FDP strongly correlated with Clauss fibrinogen, demonstrating good recovery of fibrinogen (r² = 0.99). A marked increase in Factor VIII, XIII and α₂-antiplasmin was observed in cryoprecipitate (p < 0.05). Increasing concentrations of fibrinogen from both sources were strongly correlated with ROTEM parameters (r² = 0.78–0.98). Cryoprecipitate therapy improved TG potential, increased fibrinolytic resistance and formed more homogeneous fibrin clots, compared to Fg-C. In summary, our data indicate that cryoprecipitate may be a superior source of fibrinogen to successfully control bleeding in trauma coagulopathy. However, these different products require evaluation in a clinical setting.