700 High St
Williamsport PA 17701
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License #: MD434379
Taxonomy Codes:208000000X 208M00000X
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Unveiling surface redox charge storage of interacting two-dimensional heteronanosheets in hierarchical architectures. - Nano letters
Two-dimensional (2D) heteronanosheets are currently the focus of intense study due to the unique properties that emerge from the interplay between two low-dimensional nanomaterials with different properties. However, the properties and new phenomena based on the two 2D heteronanosheets interacting in a 3D hierarchical architecture have yet to be explored. Here, we unveil the surface redox charge storage mechanism of surface-exposed WS2 nanosheets assembled in a 3D hierarchical heterostructure using in situ synchrotron X-ray absorption and Raman spectroscopic methods. The surface dominating redox charge storage of WS2 is manifested in a highly reversible and ultrafast capacitive fashion due to the interaction of heteronanosheets and the 3D connectivity of the hierarchical structure. In contrast, compositionally identical 2D WS2 structures fail to provide a fast and high capacitance with different modes of lattice vibration. The distinctive surface capacitive behavior of 3D hierarchically structured heteronanosheets is associated with rapid proton accommodation into the in-plane W-S lattice (with the softening of the E2g bands), the reversible redox transition of the surface-exposed intralayers residing in the electrochemically active 1T phase of WS2 (with the reversible change in the interatomic distance and peak intensity of W-W bonds), and the change in the oxidation state during the proton insertion/deinsertion process. This proposed mechanism agrees with the dramatic improvement in the capacitive performance of the two heteronanosheets coupled in the hierarchical structure.
Anomalous nanoinclusion effects of 2D MoS2 and WS2 nanosheets on the mechanical stiffness of polymer nanocomposites. - Nanoscale
Polymer inorganic nanosheet composites hold great promise in enhancing their physical and mechanical properties by increasing the interfacial area. Herein, we demonstrate the nanoinclusion effects of two-dimensional (2D) molybdenum disulfide (MoS2) and tungsten disulfide (WS2) nanosheets on the mechanical properties of the poly(vinyl alcohol) (PVA) polymer. At very small amounts of nanosheets (0.9 wt% for MoS2 and 2.0 wt% for WS2), nanocomposite films exhibit up to 65% improved mechanical properties than the neat PVA film because of strong non-covalent polymer-filler interactions by means of large contact area induced by the 2D geometry of nanosheets. As demonstrated by the decrease in the crystallinity of PVA and the increase in the glass transition temperature, 2D MoS2 is a more attractive filler than 2D WS2 in terms of reinforcing mechanical properties of PVA. These findings fit well with a modified Halpin-Tsai (H-T) model including a nanoscale interfacial layer that can support the observed reinforcements with extremely small 2D filler loadings. This study highlights the strong interplay between the polymer and inorganic nanosheets which plays an important role in greatly improving the mechanical stability of nanocomposites.
Surface functional groups of carbon nanotubes to manipulate capacitive behaviors. - Nanoscale
The covalent functionalization of carbon nanotubes (CNTs) is a basic but important chemistry that can modify their physicochemical properties, resolve their poor dispersion capability, and improve their capacitance to enable their use as high-energy supercapacitors. However, the relationship between functional groups on the CNT surface and their capacitive characteristics has not yet been explored. Here, we demonstrate the influence of carboxylic, sulfonic, and amine groups tethered to CNTs (Cf-CNTs, Sf-CNTs, and Nf-CNTs, respectively) on capacitor performance in an organic electrolyte. The Cf-CNTs show the highest specific capacitance of 129.4 F g(-1), four-fold greater than 31.2 F g(-1) of pristine CNTs, but they reveal the lowest rate capability of 57%. In contrast, the Sf- and Nf-CNTs exhibit specific capacitances of 70.9 F g(-1) and 83.6 F g(-1), two-fold greater than that of pristine CNTs, along with a good rate capability greater than 80%. Despite their pseudocapacitive nature, all functionalized CNTs show a cyclic stability of more than 80% after 500 cycles due to the electrochemical stability of the functional groups. As demonstrated by spectroscopic analysis, the supercapacitive behaviors of the functionalized CNTs originate from specific interactions between functional groups and lithium ions and the alteration of the electronic structure arising from covalent functionalization.
Seamless reconstruction of intact adult-born neurons by serial end-block imaging reveals complex axonal guidance and development in the adult hippocampus. - The Journal of neuroscience : the official journal of the Society for Neuroscience
In the adult mammalian hippocampus, newborn dentate granule cells are continuously integrated into the existing circuitry and contribute to specific brain functions. Little is known about the axonal development of these newborn neurons in the adult brain due to technological challenges that have prohibited large-scale reconstruction of long, thin, and complex axonal processes within the mature nervous system. Here, using a new serial end-block imaging (SEBI) technique, we seamlessly reconstructed axonal and dendritic processes of intact individual retrovirus-labeled newborn granule cells at different developmental stages in the young adult mouse hippocampus. We found that adult-born dentate granule cells exhibit tortuous, yet highly stereotyped, axonal projections to CA3 hippocampal subregions. Primary axonal projections of cohorts of new neurons born around the same time organize into laminar patterns with staggered terminations that stack along the septo-temporal hippocampal axis. Analysis of individual newborn neuron development further defined an initial phase of rapid axonal and dendritic growth within 21 d after newborn neuron birth, followed by minimal growth of primary axonal and whole dendritic processes through the last time point examined at 77 d. Our results suggest that axonal development and targeting is a highly orchestrated, precise process in the adult brain. These findings demonstrate a striking regenerative capacity of the mature CNS to support long-distance growth and guidance of neuronal axons. Our SEBI approach can be broadly applied for analysis of intact, complex neuronal projections in limitless tissue volume.
Structure and compositional control of MoO3 hybrids assembled by nanoribbons for improved pseudocapacitor rate and cycle performance. - Nanoscale
Hierarchical structures of transition metal oxides with well-defined compositions are crucial for achieving advanced electrodes for energy storage devices. Herein, we first demonstrate the hierarchically structured MoO(3) assembled by twisted nanoribbons with a hybrid composition for improved rate capability and cycle stability of the pseudocapacitor. The hierarchical, flower-like structures of MoO(3) assembled by hybrid nanoribbons were induced by the specific interactions of MoO(3) interlayers with ionic liquids (ILs), as proven by spectroscopic and electrochemical analyses. Furthermore, the interlayer modification of MoO(3) crystallites through IL interaction enabled unique pseudocapacitive behaviors for fast and reversible proton intercalation/extraction that could not be observed by conventional MoO(3). In this research, we used control samples to prove our hypothesis that the capacitor performances of MoO(3) can be improved by a hierarchical structure and hybrid composition. These structural and compositional features of the hybrids greatly enhanced the rate capability by fast ion diffusion while improving cycle stability due to efficient stress release. More importantly, we observed the dramatic enhancement of ion diffusion coefficients of hybrids for good rate capability, because ion diffusion into the layered structure is very critical for maintaining specific capacitance at the high current density. The facilitated ion diffusion is attributed to the hierarchical nanostructure for a short diffusion length and ion accessibility, the high ion mobility in hybrids, and the interlayer modification of MoO(3) by IL coating. Therefore, this research offers new insight into the rational design of advanced electrode materials on the basis of the hierarchical complex structures of transition metal oxides with well-defined hybrid compositions for future applications in energy conversion and storage.
Compliance of child care centers in Pennsylvania with national health and safety performance standards for emergency and disaster preparedness. - Pediatric emergency care
To determine the preparedness of child care centers in Pennsylvania to respond to emergencies and disasters based on compliance with National Health and Safety Performance Standards for Out-of-Home Child Care Programs.A questionnaire focusing on the presence of a written evacuation plan, the presence of a written plan for urgent medical care, the immediate availability of equipment and supplies, and the training of staff in first aid/cardiopulmonary resuscitation (CPR) as delineated in Caring for Our Children: National Health and Safety Performance Standards for Out-of-Home Child Care Programs, 2nd Edition, was mailed to 1000 randomly selected child care center administrators located in Pennsylvania.Of the 1000 questionnaires sent, 496 questionnaires were available for analysis (54% usable response rate). Approximately 99% (95% confidence interval [CI], 99%-100%) of child care centers surveyed were compliant with recommendations to have a comprehensive written emergency plan (WEP) for urgent medical care and evacuation, and 85% (95% CI, 82%-88%) practice their WEP periodically throughout the year. More than 20% of centers did not have specific written procedures for floods, earthquakes, hurricanes, blizzards, or bomb threats, and approximately half of the centers did not have specific written procedures for urgent medical emergencies such as severe bleeding, unresponsiveness, poisoning, shock/heart or circulation failure, seizures, head injuries, anaphylaxis or allergic reactions, or severe dehydration. A minority of centers reported having medications available to treat an acute asthma attack or anaphylaxis. Also, 77% (95% CI, 73%-80%) of child care centers require first aid training for each one of its staff members, and 33% (95% CI, 29%-37%) require CPR training.Although many of the child care centers we surveyed are in compliance with the recommendations for emergency and disaster preparedness, specific areas for improvement include increasing the frequency of practice of the WEP, establishing specific written procedures for external disasters and urgent medical emergencies, maintaining the immediate availability of potentially life-saving medications, and ensuring that all child care center staff are trained in first aid and CPR.
Iatrogenic superior vena caval syndrome. - JPMA. The Journal of the Pakistan Medical Association
The superior vena caval (SVC) syndrome is a common oncological emergency requiring the quick initiation of appropriate therapy. However, it may also result from a medical procedure e.g. central catheter or temporary pacing wire insertion, with symptoms usually developing acutely and dramatically. If symptoms persist despite removal of the offending device, chemotherapy and radiotherapy are obviously precluded. Alternative treatment modalities include thrombolysis, thrombectomy devices, stents, and surgery. Clinically covert thrombosis is not uncommon, and as interventions and invasive procedures requiring central venous cannulations become commonplace, this iatrogenic complications will inevitably occur more often. Even the use of ultrasound guided insertion does not avoid catheter related obstruction. A case of an iatrogenc haemodialysis catheter related SVCS is presented and the aetiopathogensis, signs and symptoms, diagnosis, and management are discussed.
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700 High St Williamsport, PA 17701
699 Rural Ave
700 High St
1521 Washington Blvd
1100 Grampian Blvd