Structural elucidation of NASICON (Na3Al2P3O12) based glass electrolyte materials: effective influence of boron and gallium

Understanding the conductivity variations induced by compositional changes in sodium super ionic conducting (NASICON) glass materials is highly relevant for applications such as solid electrolytes for sodium (Na) ion batteries. In the research reported in this paper, NASICON-based NCAP glass (Na_2.8Ca_0.1Al₂P₃O₁₂) was selected as the parent glass. The present study demonstrates the changes in the Na⁺ ion conductivity of NCAP bulk glass with the substitution of boron (NCABP: Na_2.8Ca_0.1Al₂B_0.5P_2.7O₁₂) and gallium (NCAGP: Na_2.8Ca_0.1Al₂Ga_0.5P_2.7O₁₂) for phosphorus and the resulting structural variations found in the glass network. For a detailed structural analysis of NCAP, NCABP and NCAGP glasses, micro-Raman and magic angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopic techniques (for ³¹P, ²⁷Al, ²³Na, ¹¹B and ⁷¹Ga nuclei) were used. The Raman spectrum revealed that the NCAP glass structure is more analogous to the AlPO₄ mesoporous glass structure. The ³¹P MAS-NMR spectrum illustrated that the NCAP glass structure consists of a high concentration of Q⁰ (3Al) units, followed by Q⁰ (2Al) units. The ²⁷Al MAS-NMR spectrum indicates that alumina exists at five different sites, which include AlO₄ units surrounded by AlO₆ units, Al(OP)₄, Al(OP)₅, Al(OAl)₆ and Al(OP)₆, in the NCAP glass structure. The ³¹P, ²⁷Al and ¹¹B MAS-NMR spectra of the NCABP glass revealed the absence of B–O–Al linkages and the presence of B₃–O–B₄–O–P₄ linkages which further leads to the formation of borate and borophosphate domains. The ⁷¹Ga MAS-NMR spectrum suggests that gallium cations in the NCAGP glass compete with the alumina cations and occupy four (GaO₄), five (GaO₅) and six (GaO₆) coordinated sites. The Raman spectrum of NCAGP glass indicates that sodium cations have also been substituted by gallium cations in the NCAP glass structure. From impedance analysis, the dc conductivity of the NCAP glass (∼3.13 × 10⁻⁸ S cm⁻¹) is slightly decreased with the substitution of gallium (∼2.27 × 10⁻⁸ S cm⁻¹) but considerably decreased with the substitution of boron (∼1.46 × 10⁻⁸ S cm⁻¹). The variation in the conductivity values are described based on the structural changes of NCAP glass with the substitution of gallium and boron.

Understanding the conductivity variations induced by compositional changes in sodium super ionic conducting (NASICON) glass materials is highly relevant for applications such as solid electrolytes for sodium (Na) ion batteries.     

Microtiter plate-based assay for inhibitors of penicillin-binding protein 2a from methicillin-resistant Staphylococcus aureus

Penicillin-binding protein 2a (PBP2a), the molecular determinant for high-level β-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA), is intrinsically resistant to most β-lactam antibiotics. The development and characterization of new inhibitors targeting PBP2a would benefit from an effective and convenient assay for inhibitor binding. This study was directed toward the development of a fluorescently detected β-lactam binding assay for PBP2a from MRSA. Biotinylated ampicillin and biotinylated cephalexin were tested as tagging reagents for fluorescence detection by using a streptavidin-horseradish peroxidase conjugate. Both bound surprisingly well to PBP2a, with binding constants of 1.6 ± 0.4 μM and 13.6 ± 0.8 μM, respectively. Two forms of the assay were developed, a one-step direct competition form of the assay and a two-step indirect competition form of the assay, and both forms of the assay gave comparable results. This assay was then used to characterize PBP2a binding to ceftobiprole, which gave results consistent with previous studies of ceftobiprole-PBP2a binding. This assay was also demonstrated for screening for PBP2a inhibitors by screening a set of 13 randomly selected β-lactams for PBP2a inhibition at 750 μM. Meropenem was observed to give substantial inhibition in this screen, and a follow-up titration experiment determined its apparent K(i) to be 480 ± 70 μM. The availability of convenient and sensitive microtiter-plate based assays for the screening and characterization of PBP2a inhibitors is expected to facilitate the discovery and development of new PBP2a inhibitors for use in combating the serious public health problem posed by MRSA.     

Modular hip exoskeleton improves walking function and reduces sedentary time in community-dwelling older adults

Numerous studies showed that postural balance improves through light touch on a stable surface highlighting the importance of haptic information, seemingly downplaying the mechanical contributions of the support. The present study examined the mechanical effects of canes for assisting balance in healthy individuals challenged by standing on a beam. Sixteen participants supported themselves with two canes, one in each hand, and applied minimal, preferred, or maximum force onto the canes. They positioned the canes in the frontal plane or in a tripod configuration. Statistical analysis used a linear mixed model to evaluate the effects on the center of pressure and the center of mass. The canes significantly reduced the variability of the center of pressure and the center of mass to the same level as when standing on the ground. Increasing the exerted force beyond the preferred level yielded no further benefits, although in the preferred force condition, participants exploited the altered mechanics by resting their arms on the canes. The tripod configuration allowed for larger variability of the center of pressure in the task-irrelevant anterior–posterior dimension. High forces had a destabilizing effect on the canes: the displacement of the hand on the cane handle increased with the force. Given this static instability, these results show that using canes can provide not only mechanical benefits but also challenges. From a control perspective, effort can be reduced by resting the arms on the canes and by channeling noise in the task-irrelevant dimensions. However, larger forces exerted onto the canes can also have destabilizing effects and the instability of the canes needs to be counteracted, possibly by arm and shoulder stiffness. Insights into the variety of mechanical effects is important for the design of canes and the instructions of how to use them.     

Use of MPH hemostatic powder for electrophysiology device implantation reduces postoperative rates of pocket hematoma and infection

Background: Surgical site bleeding and infection are potential complications after electrophysiology (EP) device implantation procedures. To date, there is a wide variety of tools for management of intraoperative bleeding but it still remains unclear what methods are preferred.

Objective: The aim of our study is to compare the rate of complications in patients who underwent cardiac implantable electronic device (CIED) implantation utilizing MPH hemostatic powder to the rate of complications in those patients who underwent standard procedure protocol without MPH hemostatic powder.

Methods: In our study, a new plant-derived microporous polysaccharide hemostatic powder (Arista) was used. A total of 283 consecutive patients were retrospectively studied to assess the rate of complications in patients who underwent CIED implantation with MPH hemostatic powder (n?=?77, MPH hemostatic powder) and without (n?=?206, no MPH hemostatic powder). Patients were followed for 12 months.

Results: The MPH hemostatic powder group of patients had a lower complication rate when compared to no MPH hemostatic powder, 0.3% vs. 1.7% (p?Conclusion: Using MPH hemostatic powder for post-procedural hemostasis was shown to result in a significant reduction in the rate of overall post-procedural complications (a composite endpoint of hematoma and infections), and a trend in reduction of the infections rates and device implantation site hematoma rates.     

Appraisals of robotic locomotor exoskeletons for gait: focus group insights from potential users with spinal cord injuries

Abstract

Purpose: To describe appraisals of robotic exoskeletons for locomotion by potential users with spinal cord injuries, their perceptions of device benefits and limitations, and recommendations for manufacturers and therapists regarding device use.

Materials and methods: We conducted focus groups at three regional rehabilitation hospitals and used thematic analysis to define themes.

Results: Across four focus groups, 35 adults participated; they were predominantly middle-aged, male, and diverse in terms of race and ethnicity, well educated, and not working. Participants had been living with SCI an average of two decades. Most participants were aware of exoskeletons. Some were enthusiastic about the usability of the devices while others were more circumspect. They had many questions about device affordability and usability, and were discerning in their appraisal of benefits and suitability to their particular circumstances. They reflected on device cost, the need for caregiver assistance, use of hands, and environmental considerations. They weighed the functional benefits relative to the cost of preferred activities. Their recommendations focused on cost, battery life, and independent use.

Conclusions: Potential users’ appraisals of mobility technology reflect a nuanced appreciation of device costs; functional, social, and psychological benefits; and limitations. Results provide guidance to therapists and manufacturers regarding device use.

• Implications for Rehabilitation

• Potential users of robotic locomotor exoskeletons with spinal cord injuries appreciate the functional, social, and psychological benefits that these devices may offer.

• Their appraisals reflect nuanced consideration of device cost and features, and the suitability of the assistive technology to their circumstances.

• They recommend that manufacturers focus on reducing cost, extending battery life, and features that allow independent use.

     

Postural and Metabolic Benefits of Using a Forearm Support Walker in Older Adults With Impairments

Objective

To investigate the postural and metabolic benefits a walker with adjustable elbow support (LifeWalker [LW]) can provide for ambulation in population with impairment. The clinical outcomes from the elbow support walker will be compared with standard rollator (SR) and participants predicate device (PD).

Reduced reciprocal inhibition during assisted stepping in human spinal cord injury

The aim of this study was to establish the modulation pattern of the reciprocal inhibition exerted from tibialis anterior (TA) group I afferents onto soleus motoneurons during body weight support (BWS) assisted stepping in people with spinal cord injury (SCI). During assisted stepping, the soleus H-reflex was conditioned by percutaneous stimulation of the ipsilateral common peroneal nerve at one fold TA M-wave motor threshold with a single pulse delivered at a short conditioning-test interval. To counteract movement of recording and stimulating electrodes, a supramaximal stimulus at 80–100 ms after the test H-reflex was delivered. Stimuli were randomly dispersed across the step cycle which was divided into 16 equal bins. The conditioned soleus H-reflex was significantly facilitated throughout the stance phase, while during swing no significant changes on the conditioned H-reflex were observed when compared to the unconditioned soleus H-reflex recorded during stepping. Spontaneous clonic activity in triceps surae muscle occurred in multiple phases of the step cycle at a mean frequency of 7 Hz for steps with and without stimulation. This suggests that electrical excitation of TA and soleus group Ia afferents did not contribute to manifestation of ankle clonus. Absent reciprocal inhibition is likely responsible for lack of soleus H-reflex depression in swing phase observed in these patients. The pronounced reduced reciprocal inhibition in stance phase may contribute to impaired levels of co-contraction of antagonistic ankle muscles. Based on these findings, we suggest that rehabilitation should selectively target to transform reciprocal facilitation to inhibition through computer controlled reflex conditioning protocols.