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Cyclic transparent optical polymer (CYTOP), a fluoropolymer, finds a plethora of applications in microelectronic devices for sustainable energy harvesting and memory devices. By and large, these devices demand high voltage breakdown, a high dielectric constant, transparency, charge storage, and retention capabilities. Despite many efforts, comprehensive investigation of the charge distribution, retention, and discharge studies conducted on the CYTOP film at the micro-scale remains elusive. Here, we present direct quantification and mapping of surface charge on the CYTOP surface at room temperature using two different modes of advanced surface probe microscopy i.e., Kelvin probe force microscopy (KPFM) and electrostatic force microscopy (EFM). We estimated that the surface charge densities of the CYTOP film using EFM are 1.4 and 3.3 µC/cm2 for the injection of positive and negative charges, respectively. Furthermore, we determined the charge retention time for both injected positive and negative charges. We found that the retention capacity of the negative charges on the CYTOP film is much higher as compared to the positive charges. Moreover, it is also observed that injected negative charges are strongly localized on the CYTOP surface compared to the positive counterpart. Additionally, we demonstrated that charge writing is possible on the CYTOP surface using the AFM conductive tip. These results may find potential applications in energy harvesting, sensing, memory devices, security, and surveillance.
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PURPOSE: Early-onset scoliosis (EOS) has always been a challenging situation for spine surgeons. The aim of treatment is to control the direction of curve progression to allow for the complete development of lungs. Among all the growth constructs available, traditional growth rods (TGR) and magnetically controlled growth rods (MCGR) are most widely used. The MCGR has been introduced a few years back and there is a dearth of long-term follow-up studies. The purpose of this study is to compare the effectiveness of TGR and MCGR for the treatment of EOS. METHODS: All patients of EOS managed with either TGR or MCGR were included in the study. The patients managed with other methods or having follow-up < 2-years were excluded from the study. A total of 20 patients were recruited in the MCGR group and 28 patients were recruited in the TGR group. Both groups were matched by etiology, gender, pre-operative radiological parameters, and complications including unplanned surgeries. RESULTS: The mean age in our study was 7.90 years in the MCGR group and 7.46 years in the TGR group. The mean duration of follow-up in the MCGR group was 50.89 months and in the TGR group 94.2 months. Pre-operative cobb's angle in the coronal plane and T1-S1 were comparable in both groups with a mean cobb's angle of 65.4 in MCGR and 70.5 in TGR. The mean T1-S1 length in the MCGR group was 36.1cms and in the TGR group was 35.2 cms (p = 0.18). The average increase in T1-S1 length was 1.3 cm/year in the TGR group and 1.1 cm/year in the MCGR group (p > 0.05). The TGR patients underwent 186 open lengthening surgeries and 11 unplanned surgeries for various complications. The MCGR group has 180 non-invasive lengthening with only 4 unplanned returns to OT for various causes. CONCLUSION: The curve correction was similar in both TGR and MCGR groups. The average T1-S1 length achieved on final follow-up was similar in both groups. The MCGR patients have attained similar correction with fewer invasive procedures and lesser complications compared to the TGR group.
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Escoliose , Humanos , Escoliose/cirurgia , Escoliose/diagnóstico por imagem , Feminino , Masculino , Criança , Seguimentos , Resultado do Tratamento , Pré-Escolar , Idade de Início , Fixadores InternosRESUMO
Yew plants (Taxus species) represent a genus of plants known to be highly toxic, though lethal intoxication is rare. The majority of deaths in yew berry poisonings occur due to its cardiotoxic effect, mediated through generation of a number of fatal tachy- and brady-arrhythmias. However, there are no guidelines on the most effective management in these cases, and interventions vary greatly between published reports. Here we report a case of a 20-year-old female who presented with refractory lethal arrythmia and shock refractory to conventional therapy. She presented to the emergency department and promptly required airway management and hemodynamic support necessitating intensive care unit management. She received many antiarrhythmics, digoxin immune Fab, lipid emulsification, and eventually transvenous pacemaker insertion for overdrive pacing. Despite our interventions, our patient ultimately died after a decision to withdraw care. We also reviewed 43 reports of yew poisoning cases described in the literature. We discuss the most common strategies used to treat such patients including gastric decontamination, antiarrhythmics, electrical pacing, extracorporeal life support and other therapies. We need better understanding of this condition, to identify which therapies offer maximal benefit and to optimize outcomes for this rare but often devastating toxidrome.
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Arritmias Cardíacas/induzido quimicamente , Frutas/intoxicação , Choque Cardiogênico/induzido quimicamente , Suicídio , Taxus/intoxicação , Arritmias Cardíacas/diagnóstico , Cardiotoxicidade , Evolução Fatal , Feminino , Humanos , Choque Cardiogênico/diagnóstico , Adulto JovemRESUMO
Modification of carbon nitride based polymeric 2D materials for tailoring their optical, electronic and chemical properties for various applications has gained significant interest. The present report demonstrates the synthesis of a novel modified carbon nitride framework with a remarkable 3:5 C:N stoichiometry (C3N5) and an electronic bandgap of 1.76 eV, by thermal deammoniation of the melem hydrazine precursor. Characterization revealed that in the C3N5 polymer, two s-heptazine units are bridged together with azo linkage, which constitutes an entirely new and different bonding fashion from g-C3N4 where three heptazine units are linked together with tertiary nitrogen. Extended conjugation due to overlap of azo nitrogens and increased electron density on heptazine nucleus due to the aromatic π network of heptazine units lead to an upward shift of the valence band maximum resulting in bandgap reduction down to 1.76 eV. XRD, He-ion imaging, HR-TEM, EELS, PL, fluorescence lifetime imaging, Raman, FTIR, TGA, KPFM, XPS, NMR and EPR clearly show that the properties of C3N5 are distinct from pristine carbon nitride (g-C3N4). When used as an electron transport layer (ETL) in MAPbBr3 based halide perovskite solar cells, C3N5 outperformed g-C3N4, in particular generating an open circuit photovoltage as high as 1.3 V, while C3N5 blended with MA xFA1- xPb(I0.85Br0.15)3 perovskite active layer achieved a photoconversion efficiency (PCE) up to 16.7%. C3N5 was also shown to be an effective visible light sensitizer for TiO2 photoanodes in photoelectrochemical water splitting. Because of its electron-rich character, the C3N5 material displayed instantaneous adsorption of methylene blue from aqueous solution reaching complete equilibrium within 10 min, which is significantly faster than pristine g-C3N4 and other carbon based materials. C3N5 coupled with plasmonic silver nanocubes promotes plasmon-exciton coinduced surface catalytic reactions reaching completion at much low laser intensity (1.0 mW) than g-C3N4, which showed sluggish performance even at high laser power (10.0 mW). The relatively narrow bandgap and 2D structure of C3N5 make it an interesting air-stable and temperature-resistant semiconductor for optoelectronic applications while its electron-rich character and intrasheet cavity make it an attractive supramolecular adsorbent for environmental applications.
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Anodically formed TiO2 nanotube arrays (TNTAs) constitute an optoelectronic platform that is being studied for use as a photoanode in photoelectrocatalytic cells, as an electron transport layer (ETL) in solar cells and photodetectors, and as an active layer for chemiresistive and microwave sensors. For optimal transport of charge carriers in these one-dimensional polycrystalline ordered structures, it is desirable to introduce a preferential texture with the grains constituting the nanotube walls aligned along the transport direction. Through x-ray diffraction analysis, we demonstrate that choosing the right water content in the anodization electrolyte and the use of a post-anodization zinc ion treatment can introduce a preferential texture in sub-micron length transparent TNTAs formed on non-native substrates. The incorporation of 1.5 atom% of Zn in TiO2 nanotubes prior to annealing, was found to consistently result in the strongest preferential orientation along the [001] direction. [001] oriented TNTAs exhibited a responsivity of 523 A W-1 at a bias of 2 V for 365 nm photons, which is among the highest reported performance values for ultraviolet photodetection using titania nanotubes. Furthermore, the textured nanotubes without a Zn2+ treatment showed a significantly enhanced performance in halide perovskite solar cells that used TNTAs as the ETL.
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A fluorine-doped, chlorine-intercalated carbon nitride (CNF-Cl) photocatalyst has been synthesized for simultaneous improvements in light harvesting capability along with suppression of charge recombination in bulk g-C3N4. The formation of heterojunctions of these CNF-Cl nanosheets with low bandgap, earth abundant bismuth oxyiodide (BiOI) was achieved, and the synthesized heterojunctions were tested as active photoanodes in photoelectrochemical water splitting experiments. BiOI/CNF-Cl heterojunctions exhibited extended light harvesting with a band-edge of 680 nm and generated photocurrent densities approaching 1.3 mA cm-2 under AM1.5 G one sun illumination. Scanning Kelvin probe force microscopy under optical bias showed a surface potential of 207 mV for the 50% BiOI/CNF-Cl nanocomposite, while pristine CNF-Cl and BiOI had surface photopotential values of 83 mV and 98 mV, respectively, which in turn, provided direct evidence of superior charge separation in the heterojunction blends. Enhanced charge carrier separation and improved light harvesting capability in BiOI/CNF-Cl hybrids were found to be the dominant factors in increased photocurrent, compared to the pristine constituent materials.
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Toxic shock syndrome (TSS) is caused by staphylococcal and streptococcal superantigens (SAgs) that provoke a swift hyperinflammatory response typified by a cytokine storm. The precipitous decline in the host's clinical status and the lack of targeted therapies for TSS emphasize the need to identify key players of the storm's initial wave. Using a humanized mouse model of TSS and human cells, we herein demonstrate that SAgs elicit in vitro and in vivo IL-17A responses within hours. SAg-triggered human IL-17A production was characterized by remarkably high mRNA stability for this cytokine. A distinct subpopulation of CD4+ effector memory T (TEM) cells that secrete IL-17A, but not IFN-γ, was responsible for early IL-17A production. We found mouse "TEM-17" cells to be enriched within the intestinal epithelium and among lamina propria lymphocytes. Furthermore, interfering with IL-17A receptor signaling in human PBMCs attenuated the expression of numerous inflammatory mediators implicated in the TSS-associated cytokine storm. IL-17A receptor blockade also abrogated the secondary effect of SAg-stimulated PBMCs on human dermal fibroblasts as judged by C/EBP δ expression. Finally, the early IL-17A response to SAgs was pathogenic because in vivo neutralization of IL-17A in humanized mice ameliorated hepatic and intestinal damage and reduced mortality. Together, our findings identify CD4+ TEM cells as a key effector of TSS and reveal a novel role for IL-17A in TSS immunopathogenesis. Our work thus elucidates a pathogenic, as opposed to protective, role for IL-17A during Gram-positive bacterial infections. Accordingly, the IL-17-IL-17R axis may provide an attractive target for the management of SAg-mediated illnesses.
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Interleucina-17/imunologia , Choque Séptico/imunologia , Subpopulações de Linfócitos T/imunologia , Linfócitos T/imunologia , Animais , Modelos Animais de Doenças , Citometria de Fluxo , Infecções por Bactérias Gram-Positivas/imunologia , Humanos , Memória Imunológica/imunologia , Interleucina-17/biossíntese , Camundongos , Camundongos Endogâmicos C57BL , Reação em Cadeia da Polimerase , Choque Séptico/metabolismo , Subpopulações de Linfócitos T/metabolismo , Linfócitos T/metabolismoRESUMO
Toxic shock syndrome (TSS) and other superantigen-mediated illnesses are associated with 'systemic' immunosuppression that jeopardizes the host's ability to fight pathogens. Here, we define a novel mechanism of 'local' immunosuppression that may benefit the host. Systemic exposure to staphylococcal enterotoxin B (SEB) rapidly and selectively recruited CD11b(+)Gr-1(high)Ly-6C(+) granulocytic myeloid-derived suppressor cells (MDSCs) to the liver of HLA-DR4 transgenic mice. Hepatic MDSCs inhibited SEB-triggered T cell proliferation in a reactive oxygen species-dependent manner, and ex vivo-generated human MDSCs also similarly attenuated the proliferative response of autologous T cells to SEB. We propose a role for MDSCs in mitigating excessive tissue injury during TSS.
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Enterotoxinas/imunologia , Antígeno HLA-DR4/genética , Células Supressoras Mieloides/imunologia , Choque Séptico/imunologia , Superantígenos/imunologia , Animais , Antígeno CD11b/imunologia , Proliferação de Células , Modelos Animais de Doenças , Feminino , Granulócitos/imunologia , Antígeno HLA-DR4/imunologia , Humanos , Terapia de Imunossupressão , Fígado/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Espécies Reativas de Oxigênio/imunologiaRESUMO
OBJECTIVE: To evaluate clinical and radiological outcomes of growing rod (GR) in the management of Early Onset Scoliosis (EOS) with intraspinal anomalies. BACKGROUND DATA: The effect of repeated distractions following GR, in the presence of intraspinal anomalies has not been studied. METHODS: During 2007-2012, 46 patients underwent fusionless surgery. Out of these 46 patients, 13 patients had one or more intraspinal anomalies. 11 patients had undergone prior neurosurgical procedure while 2 (filum terminale lipoma and syringomyelia) did not. A total of 88 procedures were conducted during the treatment period; 13 index surgeries, 74 distractions of GR and 1 unplanned surgery. RESULTS: The age at surgery was 6.8 ± 2.5 years (3.5-12 years). 11 patients had congenital scoliosis and 2 had idiopathic scoliosis. A total of 19 (41.30 %) intraspinal anomalies [Tethered Cord Syndrome (TCS) 08, Split Cord Malformation (SCM) 08, Syringomyelia 01, Meningomyelocele 01, Filum terminale Lipoma 01] were seen. The average lengthening procedures per patient were 5.7 (4-9) with distraction interval of 6.7 (6-7.25) months. Pre-operative Cobb angle was 78.50 ± 18.1 (54-114°) and improved to 53.10 ± 16.70 (36-84°) at final follow-up. A total of 15 complications related to implant (9), wound (2), anesthesia (2) and neurological (2) occurred in 7 patients. Among the two neurological complications, one patient sustained fall in the post-op period and reported to the emergency department with paraplegia and broken proximal screw. While other patient experienced MEP changes during index procedure. None of the patients had any neurological complications during repeated lengthening procedures. CONCLUSION: The most common cord anomalies associated with EOS in our study are TCS and SCM. Although presence of previous intraspinal anomaly does not seem to increase the incidence of neurological deficit, use of neuromonitoring is advisable for all index procedure and selected distractions. STUDY DESIGN: Level 4 (case series).
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Osteogênese por Distração/métodos , Escoliose/cirurgia , Medula Espinal/anormalidades , Medula Espinal/patologia , Cauda Equina/patologia , Criança , Pré-Escolar , Feminino , Humanos , Lipoma/complicações , Masculino , Meningomielocele/complicações , Defeitos do Tubo Neural/complicações , Osteogênese por Distração/instrumentação , Neoplasias do Sistema Nervoso Periférico/complicações , Radiografia , Escoliose/diagnóstico por imagem , Escoliose/etiologia , Escoliose/patologia , Medula Espinal/diagnóstico por imagem , Siringomielia/complicações , Resultado do TratamentoRESUMO
Triboelectric nanogenerators (TENGs) can play a pivotal role in harnessing non-utilized reciprocating motion and convert it into electrical energy that can later be stored in a battery or capacitor to power various Internet of Things-based smart electronic and wearable devices. Herein, we designed a cost-effective instrumental test bed focused on investigating the output performance of a horizontal contact separation mode triboelectric nanogenerator by varying the input parameters, such as applied force, motor speed, triboplate separation, and frequency of instrumental setup. The test bed mainly consists of three major parts: (i) application of force, (ii) tapping of TENG sample, and (iii) output parameters measurement. The output performance in terms of open circuit output voltage (VOC), short circuit current (ISC), and power density of polydimethylsiloxane-based TENG was monitored and optimized by varying the input parameters. A low-cost current measuring circuitry using an operational amplifier integrated circuit has been proposed with 92% accuracy. The maximum value of VOC and ISC was observed to be 254 V and 31.8 µA at a motor speed of 600 rpm, the distance between both the plates was 6 mm, the input applied force of 40 N, and the striking frequency of 3 Hz. The maximum power density of 2.1 W/m2 was obtained at an input impedance of 8 kΩ. The durability of the test bed as well as the TENG sample was also measured for 25 h. The degree of uncertainty was measured for VOC, ISC, and applied force and calculated to be 1.62%, 7.45%, and 6.27%, respectively.
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Plasmonics in metal nanoparticles can enhance their near field optical interaction with matter, promoting emission into selected optical modes. Here, using Ga nanoparticles with carefully tuned plasmonic resonance in proximity to MoSe2 monolayers, we show selective photoluminescence enhancement from the B-exciton and its trion with no observable A-exciton emission. The nanoengineered substrate allows for the first direct experimental observation of the B-trion binding energy in semiconducting monolayers. Using temperature-dependent photoluminescence measurements, we show the following features of the MoSe2 B-exciton family: (i) the trion binding energy has an observable temperature dependence with a decreasing trend towards low temperatures and (ii) the exciton-trion emission ratio varies non-monotonically with temperature with a steep increase in the trion emission at lower temperatures. Using detailed models, we identify the particle size required for selective excitation and describe the underlying physical processes. This opens newer avenues for selectively promoting excitonic species and tuning the effective particle lifetimes in monolayer semiconductors. These results demonstrate the excellent plasmonic properties of Ga nanoparticles, which along with facile processing techniques makes it an attractive alternative to the prevalent noble metal plasmonics having applications in flexible/stretchable materials and textiles.
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OBJECTIVE: Operative treatment of early onset scoliosis (EOS) with Magnetically Controlled Growing Rod (MCGR) in moderate-to-severe curves poses a challenge due to the limited amount of force and length available with the implant. The purpose of this study was to assess the use of the intra-operative internal spine distraction using Harrington Outrigger, before definitive implantation of MCGR, with regard to initial correction, maintenance of correction, truncal balance, and complication rates. PATIENTS AND METHODS: 16 EOS patients treated with the application of MCGR using the intra-operative internal distractor technique were included in the study. More than 50% of cases were congenital scoliosis with multiple vertebral anomalies. All patients were followed up for a minimum of 2 years. Radiological measurement of change in Cobb angle, thoracic kyphosis, lumbar lordosis, T1-S1 length, T1-T12l length, and sagittal balance were done at pre-op, immediate post-op, after 1 year, and 2 years. All the complications were noted and documented. RESULTS: The mean age of the operated patients was 8 ± 1.7 years, range (4-10 years). Mean pre-operative Cobb angle was 70.4 degrees. The mean correction of major Cobb angle was 34.6°. The percentage correction achieved in post-operative Cobb angle was about 51%. Mean change in post-operative thoracic kyphosis was 18.5° (40%). The average gain in immediate post-operative spinal length (T1-S1) and thoracic height (T1-T12) was 46.7 mm (18.3%) and 41 mm (23%), respectively. CONCLUSION: Large and rigid curves in EOS can achieve a significant correction of Cobb angle and coronal imbalance during the index operation, by the use of intra-operative internal distraction at the time of MCGR insertion. LEVEL AND TYPE OF STUDY: Retrospective clinical study, level 4.
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Cifose , Escoliose , Humanos , Pré-Escolar , Criança , Escoliose/cirurgia , Resultado do Tratamento , Vértebras Torácicas/cirurgia , Estudos Retrospectivos , Cifose/cirurgiaRESUMO
Cellulose nanocrystals (CNC) are the focus of significant attention in the broad area of sustainable technologies for possessing many desirable properties such as a large surface area, high strength and stiffness, outstanding colloidal stability, excellent biocompatibility and biodegradability, low weight and abundance in nature. Yet, a fundamental understanding of the micro- and nanoscale electrical charge distribution on nanocellulose still remains elusive. Here we present direct quantification and mapping of surface charges on CNCs at ambient condition using advanced surface probe microscopy techniques such as Kelvin probe force microscopy (KPFM), electrostatic force microscopy (EFM) and force-distance (F-D) curve measurements. We show by EFM measurements that the surface charge in the solid-state (as contrasted with liquid dispersions) present at ambient condition on CNCs provided by Innotech Alberta is intrinsically negative and the charge density is estimated to be 13 µC/cm2. These charges also result in CNCs having two times the adhesive force exhibited by SiO2 substrates in adhesion mapping studies. The origin of negative surface charge is likely due to the formation of CNCs through sulfuric acid hydrolysis where sulfate half esters groups remained on the surface (Johnston et al., 2018).
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Celulose/química , Microscopia de Força Atômica/métodos , Microscopia de Varredura por Sonda/métodos , Nanopartículas/química , Hidrólise , Fenômenos Físicos , Dióxido de Silício , Ácidos Sulfúricos/química , Propriedades de SuperfícieRESUMO
We report highly fluorescent cellulose nanocrystals (CNCs) formed by conjugating a carboxylated zinc phthalocyanine (ZnPc) to two different types of CNCs. The conjugated nanocrystals (henceforth called ZnPc@CNCs) were bright green in color and exhibited absorption and emission maxima at â¼690 and â¼715 nm, respectively. The esterification protocol employed to covalently bind carboxylated ZnPc to surface hydroxyl group rich CNCs was expected to result in a monolayer of ZnPc on the surface of the CNCs. However, dynamic light scattering (DLS) studies indicated a large increase in the hydrodynamic radius of CNCs following conjugation to ZnPc, which suggests the binding of multiple ZnPc molecular layers on the CNC surface. This binding could be through co-facial π-stacking of ZnPc, where ZnPc metallophthalocyanine rings are horizontal to the CNC surface. The other possible binding mode would give rise to conjugated systems where ZnPc metallophthalocyanine rings are oriented vertically on the CNC surface. Density functional theory based calculations showed stable geometry following the conjugation protocol that involved covalently attached ester bond formation. The conjugates demonstrated superior performance for potential sensing applications through higher photoluminescence quenching capabilities compared to pristine ZnPc.
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Leading edge p-i-n type halide perovskite solar cells (PSCs) severely underperform n-i-p PSCs. p-i-n type PSCs that use PEDOT:PSS hole transport layers (HTLs) struggle to generate open-circuit photovoltage values higher than 1 V. NiO HTLs have shown greater promise in achieving high Voc values albeit inconsistently. In this report, a NiO nanomesh with Ni3+ defect grown by the hydrothermal method was used to obtain PSCs with Voc values that consistently exceeded 1.10 V (champion Voc = 1.14 V). A champion device photoconversion efficiency of 17.75% was observed. Density functional theory modeling was used to understand the interfacial properties of the NiO/perovskite interface. The PCE of PSCs constructed using the Ni3+-doped NiO nanomesh HTL was â¼34% higher than that of conventional compact NiO-based perovskite solar cells. A suite of characterization techniques such as transmission electron microscopy, field emission scanning electron microscopy, intensity-modulated photocurrent spectroscopy, intensity-modulated photovoltage spectroscopy, time-resolved photoluminescence, steady-state photoluminescence, and Kelvin probe force microscopy provided evidence of better film quality, enhanced charge transfer, and suppressed charge recombination in PSCs based on hydrothermally grown NiO nanostructures.
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Polyethersulfone (PES) is a polymeric permeable material used in ultrafiltration (UF) membranes due to its high thermomechanical and chemical stability. The hydrophobic nature of PES membranes renders them prone to fouling and restricts the practical applications of PES in the fabrication of water treatment membranes. The present study demonstrates a non-solvent-induced phase separation (NIPS) approach to modifying PES membranes with different concentrations of discrete TiO2 nanotubes (TNTs). Zeta potential and contact angle measurements showed enhanced hydrophilicity and surface negative charge in TNTs/PES nanocomposite membranes compared to unmodified PES membranes. To discern the antifouling and permeation properties of the TNTs/PES membranes, steam assisted gravity drainage (SAGD) wastewater obtained from the Athabasca oil sands of Alberta was used. The TiO2 modified polymer nanocomposite membranes resulted in a higher organic matter rejection and water flux than the unmodified PES membrane. The addition of discrete TNTs at 1 wt% afforded maximum water flux (82 L/m2 h at 40 psi), organic matter rejection (53.9%), and antifouling properties (29% improvement in comparison to pristine PES membrane). An enhancement in fouling resistance of TNTs/PES nanocomposite membranes was observed in flux recovery ratio experiments.
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Although the generation of mechanical stress in the anode material is suggested as a possible reason for electrode degradation and fading of storage capacity in batteries, only limited knowledge of the electrode stress and its evolution is available at present. Here, we show real-time monitoring of the interfacial stress of a few-layer MoS2 system under the sodiation/desodiation process using microcantilever electrodes. During the first sodiation with a voltage plateau of 1.0 to 0.85 V, the MoS2 exhibits a compressive stress (2.1 Nm-1), which is substantially smaller than that measured (9.8 Nm-1) during subsequent plateaus at 0.85 to 0.4 V due to the differential volume expansion of the MoS2 film. The conversion reaction to Mo below 0.1 V generates an anomalous compressive stress of 43 Nm-1 with detrimental effects. These results also suggest the existence of a separate discharge stage between 0.6 and 0.1 V, where the generated stress is only approximately one-third of that observed below 0.1 V. This approach can be adapted to help resolve the localized stress in a wide range of electrode materials, to gain additional insights into mechanical effects of charge storage, and for long-lifetime battery design.
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STUDY DESIGN: A prospective single-center study. OBJECTIVE: The aim of this study was to record the characteristic forces and lengths observed during distraction episodes in early-onset scoliosis (EOS), and analyze their interdependencies on the key variability among the patients. SUMMARY OF BACKGROUND DATA: The goal of the growing-rod technique is to achieve deformity correction alongside maintaining growth of the spine. The deformity correction is achieved during the initial surgery, but follow-up distraction episodes are necessary to maintain the growth. The key variables, under the control of a surgeon, that affect the growth are the applied distraction forces and the distraction lengths. Since the advent of dual growth rod technique, there have been many studies exploring the relationship between these and the actual growth. However, there is sparse evidence on the actual magnitude of distraction forces, and none on its association with patient's parameters such as sex, age, and deformity. METHODS: In a consecutive series of 47 patients implanted with dual growth rods, the distraction forces (in N) and the lengths (in mm) achieved during each distraction episode and compared against the episode-specific demographics. The values obtained from each side, that is, concave and convex sides, were averaged to calculate the mean. Statistical analysis was performed using t-distribution because for each normalized time points (distraction episode). RESULTS: In cumulative, the distraction force increased by an amount of 268%, with 120% increase in the early stages (distractions episodes 1-6) and 68% increase in the later stages (distractions episodes 6-11), whereas the cumulative decrease in the length over 11 distractions episodes was 47%, with 34% and 20% in the early and later stages, respectively. The study does not identify any significant trend with respect to sex, age, and deformity. CONCLUSION: The distraction force and the length increased and decreased respectively with every consecutive distraction episode, with no correlation to sex, age, extent of deformity, or the extent of correction. LEVEL OF EVIDENCE: 5.
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Desenvolvimento Ósseo , Osteogênese por Distração/instrumentação , Próteses e Implantes , Escoliose/diagnóstico por imagem , Escoliose/cirurgia , Desenvolvimento Ósseo/fisiologia , Criança , Feminino , Humanos , Masculino , Osteogênese por Distração/métodos , Estudos Prospectivos , Estudos Retrospectivos , Coluna Vertebral/diagnóstico por imagem , Coluna Vertebral/cirurgia , Resultado do TratamentoRESUMO
The direct conversion of mechanical energy into electricity by nanomaterial-based devices offers potential for green energy harvesting 1-3 . A conventional triboelectric nanogenerator converts frictional energy into electricity by producing alternating current (a.c.) triboelectricity. However, this approach is limited by low current density and the need for rectification 2 . Here, we show that continuous direct-current (d.c.) with a maximum density of 106 A m-2 can be directly generated by a sliding Schottky nanocontact without the application of an external voltage. We demonstrate this by sliding a conductive-atomic force microscope tip on a thin film of molybdenum disulfide (MoS2). Finite element simulation reveals that the anomalously high current density can be attributed to the non-equilibrium carrier transport phenomenon enhanced by the strong local electrical field (105-106 V m-2) at the conductive nanoscale tip 4 . We hypothesize that the charge transport may be induced by electronic excitation under friction, and the nanoscale current-voltage spectra analysis indicates that the rectifying Schottky barrier at the tip-sample interface plays a critical role in efficient d.c. energy harvesting. This concept is scalable when combined with microfabricated or contact surface modified electrodes, which makes it promising for efficient d.c. triboelectricity generation.
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Incidence of back pain among children and adolescents is gradually increasing. Children undergo extensive diagnostic workup that ultimately results in a nonconfirmative diagnosis. A good history and clinical examination can, to a large extent help differentiate non-specific from organic causes of backache. Diagnostic workup may be initiated if symptoms are severe and/or persistant. The authors review some of the common causes of back pain in pediatric population, clinical presentations, and the relevant investigations along with their management.