Characterization of parotid gland tumors using diffusion-relaxation correlation spectrum imaging: a preliminary study

AIM

To assess the performance of diffusion-relaxation correlation spectrum imaging (DR-CSI) in the characterization of parotid gland tumors.

MATERIALS AND METHODS

Twenty-five pleomorphic adenomas (PA) patients, 9 Warthin's tumors (WT) patients and 7 malignant tumors (MT) patients were prospectively recruited. DR-CSI (7 b-values combined with 5 TEs, totally 35 diffusion-weighted images) was scanned for pre-treatment assessment. Diffusion (D)-T2 signal spectrum summating all voxels were built for each patient, characterized by D-axis with range 0∼5 × 10-3 mm2/s, and T2-axis with range 0∼300ms. With boundaries of 0.5 and 2.5 × 10-3 mm2/s for D, all spectra were divided into three compartments labeled A (low D), B (mediate D) and C (high D). Volume fractions acquired from each compartment (VA, VB, VC) were compared among PA, WT and MT. Diagnostic performance was assessed using receiver operating characteristic analysis and area under the curve (AUC).

RESULTS

Each subtype of parotid tumors had their specific D-T2 spectrum. PA showed significantly lower VA (8.85 ± 4.77% vs 20.68 ± 10.85%), higher VB (63.40 ± 8.18% vs 43.05 ± 7.16%), and lower VC (27.75 ± 8.51% vs 36.27 ± 11.09) than WT (all p<0.05). VB showed optimal diagnostic performance (AUC 0.969, sensitivity 92.00%, specificity 100.00%). MT showed significantly higher VA (21.23 ± 12.36%), lower VB (37.09 ± 6.43%), and higher VC (41.68 ± 13.72%) than PA (all p<0.05). Similarly, VB showed optimal diagnostic performance (AUC 0.994, sensitivity 96.00%, specificity 100.00%). No significant difference of VA, VB and VC was found between WT and MT.

CONCLUSIONS

DR-CSI might be a promising and non-invasive way for characterizing parotid gland tumors.

Balanced NOx- and Proton Adsorption for Efficient Electrocatalytic NOx- to NH3 Conversion

Electrocatalytic nitrate (NO3-)/nitrite (NO2-) reduction reaction (eNOx-RR) to ammonia under ambient conditions presents a green and promising alternative to the Haber-Bosch process. Practically available NOx- sources, such as wastewater or plasma-enabled nitrogen oxidation reaction (p-NOR), typically have low NOx- concentrations. Hence, electrocatalyst engineering is important for practical eNOx-RR to obtain both high NH3 Faradaic efficiency (FE) and high yield rate. Herein, we designed balanced NOx- and proton adsorption by properly introducing Cu sites into the Fe/Fe2O3 electrocatalyst. During the eNOx-RR process, the H adsorption is balanced, and the good NOx- affinity is maintained. As a consequence, the designed Cu-Fe/Fe2O3 catalyst exhibits promising performance, with an average NH3 FE of ∼98% and an average NH3 yield rate of 15.66 mg h-1 cm-2 under the low NO3- concentration (32.3 mM) of typical industrial wastewater at an applied potential of -0.6 V versus reversible hydrogen electrode (RHE). With low-power direct current p-NOR generated NOx- (23.5 mM) in KOH electrolyte, the Cu-Fe/Fe2O3 catalyst achieves an FE of ∼99% and a yield rate of 15.1 mg h-1 cm-2 for NH3 production at -0.5 V (vs RHE). The performance achieved in this study exceeds industrialization targets for NH3 production by exploiting two available low-concentration NOx- sources.

Integration of Metal-Organic Frameworks and Metals: Synergy for Electrocatalysis

Electrocatalysis is a highly promising technology widely used in clean energy conversion. There is a continuing need to develop advanced electrocatalysts to catalyze the critical electrochemical reactions. Integrating metal active species, including various metal nanostructures (NSs) and atomically dispersed metal sites (ADMSs), into metal-organic frameworks (MOFs) leads to the formation of promising heterogeneous electrocatalysts that take advantage of both components. Among them, MOFs can provide support and protection for the active sites on guest metals, and the resulting host-guest interactions can synergistically enhance the electrocatalytic performance. In this review, three key concerns on MOF-metal heterogeneous electrocatalysts regarding the catalytic sites, conductivity, and catalytic stability are first presented. Then, rational integration strategies of MOFs and metals, including the integration of metal NSs via surface anchoring, space confining, and MOF coating, as well as the integration of ADMSs either with the metal nodes/linkers or within the pores of MOFs, along with their recent progress on synergistic cooperation for specific electrochemical reactions are summarized. Finally, current challenges and possible solutions in applying these increasingly concerned electrocatalysts are also provided.

Achieving Tunable Selectivity and Activity of CO2 Electroreduction to CO via Bimetallic Silver-Copper Electronic Engineering

Limited comprehension of the reaction mechanism has hindered the development of catalysts for CO₂ reduction reactions (CO₂ RR). Here, the bimetallic AgCu nanocatalyst platform is employed to understand the effect of the electronic structure of catalysts on the selectivity and activity for CO₂ electroreduction to CO. The atomic arrangement and electronic state structure vary with the atomic ratio of Ag and Cu, enabling tunable d-band centers to optimize the binding strength of key intermediates. Density functional theory calculations confirm that the variation of Cu content greatly affects the free energy of *COOH, *CO (intermediate of CO), and *H (intermediates of H₂ ), which leads to the change of the rate-determining step. Specifically, Ag₉₆ Cu₄ reduces the free energy of the formation of *COOH while maintaining a relatively high theoretical overpotential for hydrogen evolution reaction(HER), thus achieving the best CO selectivity. While Ag₇₀ Cu₃₀ shows relatively low formation energy of both *COOH and *H, the compromised thermodynamic barrier and product selectivity allows Ag₇₀ Cu₃₀ the best CO partial current density. This study realizes the regulation of the selectivity and activity of electrocatalytic CO₂ to CO, which provides a promising way to improve the intrinsic performance of CO₂ RR on bimetallic AgCu.

Temperature-Induced Structure Transformation from Co0.85Se to Orthorhombic Phase CoSe2 Realizing Enhanced Hydrogen Evolution Catalysis

Transition-metal chalcogenides (TMC) have been widely studied as active electrocatalysts toward the hydrogen evolution reaction due to their suitable d-electron configuration and relatively high electrical conductivity. Herein, we develop a feasible method to synthesize an orthorhombic phase of CoSe₂ (o-CoSe₂) from the regeneration of Co_0.85Se, where the temperature plays a key role in controlling the structure transformation. To the best of our knowledge, this is the first report about this synthetic route for o-CoSe₂. The resulting o-CoSe₂ catalysts exhibit enhanced hydrogen evolution reaction performance with an overpotential of 220 mV to reach 10 mA cm^-2 in 1.0 M KOH. Density functional theory calculations further reveal that the change in the Gibbs free energy of hydrogen, water adsorption energy, and the downshifted d-band center make o-CoSe₂ more suitable for accelerating the HER process.

Enhanced Electrochemical Reduction of CO2 to CO on Ag/SnO2 by a Synergistic Effect of Morphology and Structural Defects

Silver (Ag)-based materials are considered to be promising materials for electrochemical reduction of CO₂ to produce CO, but the selectivity and efficiency of traditional polycrystalline Ag materials are insufficient; there still exists a great challenge to explore novel modified Ag based materials. Herein, a nanocomposite of Ag and SnO₂ (Ag/SnO₂ ) for efficient reduction of CO₂ to CO is reported. HRTEM and XRD patterns clearly demonstrated the lattice destruction of Ag and the amorphous SnO₂ in the Ag/SnO₂ nanocomposite. Electrochemical tests indicated the nanocomposite containing 15% SnO₂ possesses highest catalytic selectivity featured by a CO faradaic efficiency (FE) of 99.2% at -0.9 V versus reversible hydrogen electrode (vs RHE) and FE>90% for the CO product at a wide potential range from -0.8 V to -1.4 V vs RHE. Experimental characterization and analysis showed that the high catalytic performance is attributed to not only the branched morphology of Ag/SnO₂ nanocomposites (NCs), which endows the maximum exposure of active sites, but also the special adsorption capacity of abundant defect sites in the crystal for *COOH (the key intermediate of CO formation), which improves the intrinsic activity of the catalyst. But equally important, the existed SnO₂ also plays an important role in inhibiting hydrogen evolution reaction (HER) and anchoring defect sites. This work demonstrates the use of crystal defect engineering and synergy in composite to improve the efficiency of electrocatalytic CO₂ reduction reaction (CO₂ RR).

Correlations between microbiota and metabolites after faecal microbiota transfer in irritable bowel syndrome

Faecal microbiota transfer (FMT) consists of the infusion of donor faecal material into the intestine of a patient with the aim to restore a disturbed gut microbiota. In this study, it was investigated whether FMT has an effect on faecal microbial composition, its functional capacity, faecal metabolite profiles and their interactions in 16 irritable bowel syndrome (IBS) patients. Faecal samples from eight different time points before and until six months after allogenic FMT (faecal material from a healthy donor) as well as autologous FMT (own faecal material) were analysed by 16S RNA gene amplicon sequencing and gas chromatography coupled to mass spectrometry (GS-MS). The results showed that the allogenic FMT resulted in alterations in the microbial composition that were detectable up to six months, whereas after autologous FMT this was not the case. Similar results were found for the functional profiles, which were predicted from the phylogenetic sequencing data. While both allogenic FMT as well as autologous FMT did not have an effect on the faecal metabolites measured in this study, correlations between the microbial composition and the metabolites showed that the microbe-metabolite interactions seemed to be disrupted after allogenic FMT compared to autologous FMT. This shows that FMT can lead to altered interactions between the gut microbiota and its metabolites in IBS patients. Further research should investigate if and how this affects efficacy of FMT treatments.

Planar Fully Stretchable Lithium-Ion Batteries Based on a Lamellar Conductive Elastomer

Stretchable lithium-ion batteries (LIBs) have attracted great attention as a promising power source in the emerging field of wearable electronics. Despite the recent advances in stretchable electrodes, separators, and sealing materials, building stretchable full batteries remains a big challenge. Herein, a simple strategy to prepare stretchable electrodes and separators at the full battery scale is reported. Then, electrostatic spraying is used to make the anode and cathode on an elastic current collector. Finally, a polyvinylidene fluoride/thermoplastic polyurethane nanofiber separator is hot-sandwiched between the cathode and anode. The fabricated battery shows stable electrochemical performance during repeatable release-stretch cycles. In particular, a stable capacity of 6 mA•h/cm² at the current rate of 0.5 C can be achieved for the fully stretchable LIB. More importantly, over 70% of the initial capacity can be maintained after 100 cycles with ∼150% stretch.

The study on pathological mechanism and solution method for spinal cord ischemia reperfusion injury

OBJECTIVE

We aimed at investigating the pathological mechanism changing of injury during reperfusion injury, reperfusion time correlation and compliance, finding the blood supply and improving the secondary damage.

MATERIALS AND METHODS

A total of 180 patients who underwent a surgical procedure and that received normal saline intraperitoneally immediately after the patients' aortic occlusions were investigated. Patients were divided in three groups. Experimental conditions and programs were designed for various approaches.

RESULTS

Thirty min after the onset of ischemia, we found a decrease in the local blood flow in the lumbar spinal cord, almost -77.48% of the baseline, which was reversed partially by initial reperfusion, even exceeding the baseline level. However, 1 hour after reperfusion, the blood flow was again decreased to the level below the baseline, followed by a decline to 207.13% ± 38.25 PU for 3 h without any recovery. Attenuating this secondary damage with neuroprotective strategies requires an understanding of these pathophysiologic processes.

CONCLUSIONS

This study showed the pathological mechanism changes during reperfusion injury and reperfusion time correlation and compliance, and analyzed some of the important pathophysiologic processes involved in secondary damage after spinal cord injury. Moreover, our research discusses a number of pharmacologic therapies that have either been studied or have future potential for this devastating injury.

Effects of zoledronic acid on bone mineral density around prostheses and bone metabolism markers after primary total hip arthroplasty in females with postmenopausal osteoporosis

INTRODUCTION

To investigate the effect of zoledronic acid on periprosthetic bone mineral density (BMD) and bone metabolism markers after primary total hip arthroplasty in females with postmenopausal osteoporosis.

METHODS

From November 2015 to April 2016, 40 female patients who met the inclusion criteria were randomized into two groups: a control group (calcium + calcitriol) and a zoledronic acid group (calcium + calcitriol + zoledronic acid). At 1 week and 3, 6, and 12 months after operation, BMD was obtained through dual-energy X-ray absorptiometry (DEXA). At pre-operation and at 3, 6, and 12 months after the operation, levels of bone metabolism markers were obtained by serum examination.

RESULTS

Loss of BMD was significantly more pronounced in the control group than in the ZOL group in zones 1, 4, 6, and 7 at 6 months and in zones 1, 2, 4, 6, and 7 at 12 months after the operation. The levels of bone-resorption marker (β-CTX) were significantly lower in the ZOL group than in the control group at 3, 6, and 12 months after operation. The levels of bone-formation marker (TP1NP) performed statistically differences only at 12 months after the operation in these two groups.

CONCLUSIONS

Receiving an intravenous infusion of 5 mg zoledronic acid after THA can effectively reduce periprosthetic BMD loss and improve bone remodeling in females with postmenopausal osteoporosis. Zoledronic acid significantly inhibited bone mass loss in zones 1, 2, 4, 6, and 7 after THA and inhibited bone-resorption marker (β-CTX) to improve bone remodeling. Zoledronic acid treatment is potentially important for patients with osteoporosis after THA.

Association of serum galectin-3 with risks of death and vascular events in acute ischaemic stroke patients: the role of hyperglycemia

BACKGROUND AND PURPOSE

Whether the association between galectin-3 and stroke outcome is modified by fasting plasma glucose (FPG) is unknown. The aim was to evaluate the prognostic effect of galectin-3 amongst ischaemic stroke patients stratified by FPG.

METHODS

In all, 3082 ischaemic stroke patients were included in this study and serum galectin-3 was tested at baseline. The primary outcome was a composite outcome of death and vascular events, and secondary outcomes were death, stroke recurrence and vascular events within 1 year after stroke.

RESULTS

Increased galectin-3 was significantly associated with the primary outcome, stroke recurrence and vascular events in the patients with hyperglycemia but not in those with normoglycemia (P for interaction < 0.05 for all). The multivariate-adjusted hazard ratios (95% confidence intervals) were 1.72 (1.05-2.84), 2.64 (1.14-6.12) and 2.68 (1.33-5.38) for the primary outcome, stroke recurrence and vascular events, respectively. A linear association between galectin-3 and the primary outcome was observed in hyperglycemic patients (P for linearity = 0.007).

CONCLUSION

Increased galectin-3 was associated with the primary outcome, stroke recurrence and vascular events within 1 year after stroke in the patients with hyperglycemia, suggesting that galectin-3 may be an important prognostic factor for ischaemic stroke patients with hyperglycemia.

Palladium-Cobalt Nanowires Decorated with Jagged Appearance for Efficient Methanol Electro-oxidation

Inexpensive, active, stable, and CO-tolerant nonplatinum catalysts for efficient methanol electro-oxidation are highly desirable to direct methanol fuel cell (DMFC) technology; however, it is still challenging. In this study, we report palladium and cobalt nanowires with jagged appearance (Pd-Co J-NWs), synthesized via first anodic-aluminum-oxide template-confined electrodeposition of Pd-Co regular nanowires, followed by a wet-chemical transformation. Benefiting from the "jagged" appearance and Co dopants, the mass and specific activities of Pd-Co J-NWs for methanol electro-oxidation are evaluated ∼3.2 times and ∼2.1 times as high as those of Pd/C catalysts, respectively. After chronoamperometric measurements for 2000 s, the catalytic stability of Pd-Co J-NWs is ∼5.4 times higher compared to that of commercial Pd/C. Moreover, the onset potential of CO-stripping of Pd-Co J-NWs (0.5 V) is lower than that of Pd/C (0.7 V), suggesting CO antipoisoning. Our approach to Pd-Co J-NWs catalysts provides an experimental guideline for designing other high-performance nonplatinum catalysts, which is promising for future DMFC industry.

Serum 25-hydroxyvitamin D deficiency predicts poor outcome amongst acute ischaemic stroke patients with low high density lipoprotein cholesterol

BACKGROUND AND PURPOSE

Current observational studies indicate that a lower vitamin D level is associated with a higher risk of poor ischaemic stroke prognosis. Whether this association is affected by lipid levels is unclear. Our aim was to examine the effect of serum vitamin D especially its deficiency on the global outcome of ischaemic stroke stratified by individual lipid component level.

METHODS

A total of 3181 ischaemic patients from China Antihypertensive Trial in Acute Ischaemic Stroke were included in this study and their baseline serum 25-hydroxyvitamin D levels were tested. They were prospectively followed up for death, major disability and vascular events for 3 months after acute ischaemic stroke. A multivariable logistic model was used to evaluate the association between serum 25-hydroxyvitamin D levels and clinical outcomes of ischaemic stroke in the 3-month period of follow-up in all patients and in different lipid-level subgroups.

RESULTS

Vitamin D deficiency was associated with poor clinical outcomes only in ischaemic stroke patients with high density lipoprotein cholesterol (HDLC) <1.04 mmol/l rather than all patients. The multivariable adjusted odds ratios (95% confidence intervals) of major disability and composite adverse events were 1.98 (1.08-3.63) and 2.24 (1.22-4.12), respectively. There was a significant interaction effect between vitamin D and HDLC levels on major disability and the composite outcome (P for interaction < 0.05 for both). A significant linear trend existed between 25-hydroxyvitamin D and risk of poor prognosis (P = 0.03).

CONCLUSIONS

Vitamin D deficiency may be merely an independent risk factor of poor prognosis in ischaemic stroke patients with low HDLC level.

Building better lithium-sulfur batteries: from LiNO3 to solid oxide catalyst

Lithium nitrate (LiNO₃) is known as an important electrolyte additive in lithium-sulfur (Li-S) batteries. The prevailing understanding is that LiNO₃ reacts with metallic lithium anode to form a passivation layer which suppresses redox shuttles of lithium polysulfides, enabling good rechargeability of Li-S batteries. However, this view is seeing more challenges in the recent studies, and above all, the inability of inhibiting polysulfide reduction on Li anode. A closely related issue is the progressive reduction of LiNO₃ on Li anode which elevates internal resistance of the cell and compromises its cycling stability. Herein, we systematically investigated the function of LiNO₃ in redox-shuttle suppression, and propose the suppression as a result of catalyzed oxidation of polysulfides to sulfur by nitrate anions on or in the proximity of the electrode surface upon cell charging. This hypothesis is supported by both density functional theory calculations and the nitrate anions-suppressed self-discharge rate in Li-S cells. The catalytic mechanism is further validated by the use of ruthenium oxide (RuO₂, a good oxygen evolution catalyst) on cathode, which equips the LiNO₃-free cell with higher capacity and improved capacity retention over 400 cycles.

Effect of single nucleotide polymorphisms in the ATP-binding cassette B1 gene on the clinical outcome of traumatic brain injury

The critical role of ATP-binding cassette B1 (ABCB1) in the function of the blood-brain barrier led us to conducted this prospective study in order to investigate the clinical outcome of patients suffering from severe traumatic brain injury. A total of 182 patients with traumatic brain injury were included in our study. Genotyping of ABCB1 C3435T and G2677T/A was conducted using polymerase chain reaction-restriction fragment length polymorphism. Using multivariate-logistic regression analysis, we found that patients carrying the CT+CC genotype of ABCB1 C3435T were more likely to have a better neurological outcome when compared with the TT genotype (odds ratio = 2.71, 95% confidence interval = 1.12-6.86). However, no significant association was found between the G2677T/A polymorphism and outcome of traumatic brain injury patients. Our study provides important information regarding the prognostic value of ABCB1 C3435T, and the ABCB1 C3435T polymorphism may be used as a predictive marker for the outcome of traumatic brain injury patients.

Co3O4 nanoparticles decorated carbon nanofiber mat as binder-free air-cathode for high performance rechargeable zinc-air batteries

An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization and a post annealing process in air at a moderate temperature. Electrochemical studies suggest that the nanohybrid material effectively catalyzes oxygen reduction reaction via an ideal 4-electron transfer process and outperforms Pt/C in catalyzing oxygen evolution reactions. Accordingly, the prototype ZnABs exhibit a low discharge-charge voltage gap (e.g. 0.7 V, discharge-charge at 2 mA cm(-2)) with higher stability and longer cycle life compared to their counterparts constructed using Pt/C in air-cathode. Importantly, the hybrid nanofiber mat readily serves as an integrated air-cathode without the need of any further modification. Benefitting from its efficient catalytic activities and structural advantages, particularly the 3D architecture of highly conductive CNFs and the high loading density of strongly attached Co3O4 NPs on their surfaces, the resultant ZnABs show significantly improved performance with respect to the rate capability, cycling stability and current density, promising good potential in practical applications.

Eggplant-derived microporous carbon sheets: towards mass production of efficient bifunctional oxygen electrocatalysts at low cost for rechargeable Zn–air batteries

Microporous carbon sheets derived from eggplant via carbonization and KOH activation serve as efficient bifunctional catalysts for high performance zinc–air batteries.

Cobalt sulfide nanoparticles impregnated nitrogen and sulfur co-doped graphene as bifunctional catalyst for rechargeable Zn–air batteries

Cobalt sulfide nanoparticle impregnated nitrogen and sulfur co-doped graphene nanosheets synthesized in water-based media equip Zn–air batteries with good cycling stability.

Co3O4 nanoparticles grown on N-doped Vulcan carbon as a scalable bifunctional electrocatalyst for rechargeable zinc–air batteries

Balancing the loading of in situ grown Co₃O₄ nanoparticles with the N-doped Vulcan carbon underneath is essential to produce scalable high-performance bifunctional catalysts of Co₃O₄/NVC for rechargeable Zn–air batteries.

Clinical significance of fibroblast growth factor receptor-3 mutations in bladder cancer: a systematic review and meta-analysis

Mutations in the fibroblast growth factor receptor-3 (FGFR3) gene are frequently found in bladder cancer, but their prognostic value remains controversial. To globally summarize the association between FGFR3 mutations and the grade and stage of bladder cancer, and to analyze the predictive role of FGFR3 mutations with respect to survival, eligible studies were identified and assessed for quality through multiple search strategies. Risk ratio (RR) data were collected from studies comparing the number of FGFR3 mutants among low-grade and early-stage bladder cancer patients to the number among high-grade and late-stage patients. Hazard ratio (HR) data were collected from studies comparing survival in patients with mutant FGFR3 genes to those with wild-type genes. Studies were pooled, and the RRs of grade and stage and the HRs of survival were calculated. Thirty studies were included in the present meta-analysis. FGFR3 mutations were found to be closely associated with low-grade and early-stage bladder cancer, showing pooled RRs = 2.948 [95% confidence interval (CI) = 2.357-3.688] and 2.845 (95%CI = 2.145- 3.773), respectively. Notably, patients with FGFR3 mutations tended to show better disease-, progress-, and recurrence-free survival (HR = 0.561, 95%CI = 0.405-0.779), and better disease-specific survival (HR = 0.363, 95%CI = 0.266-0.496). This study demonstrated that FGFR3 mutations are closely related to low grade, early stage, and better survival among bladder cancer patients.

N-containing functional groups induced superior cytocompatible and hemocompatible graphene by NH₂ ion implantation

Graphene is functionalized with amine by NH2 ion implantation at room temperature in vacuum. The reaction is featured by nucleophilic substitution of C-O groups by the ammonia radicals. The presence of N-containing functional groups in graphene is identified by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. N element was successfully introduced to graphene, the atomic ratio of N to C rose to 3.12 %. NH2 ion implanted graphene (G-NH2) is a better hydrophilic material than pristine grahene according to the contact angle experiment. Mouse fibroblast cells and human endothelial cells cultured on G-NH2 displayed superior cell-viability, proliferation and stretching over that on pristine graphene. Platelet adhesion, hemolysis and Kinetic-clotting time were measured on G-NH2, showing excellent anticoagulation, with as good hemolysis as pristine graphene.

Single-atom Catalysis Using Pt/Graphene Achieved through Atomic Layer Deposition

Platinum-nanoparticle-based catalysts are widely used in many important chemical processes and automobile industries. Downsizing catalyst nanoparticles to single atoms is highly desirable to maximize their use efficiency, however, very challenging. Here we report a practical synthesis for isolated single Pt atoms anchored to graphene nanosheet using the atomic layer deposition (ALD) technique. ALD offers the capability of precise control of catalyst size span from single atom, subnanometer cluster to nanoparticle. The single-atom catalysts exhibit significantly improved catalytic activity (up to 10 times) over that of the state-of-the-art commercial Pt/C catalyst. X-ray absorption fine structure (XAFS) analyses reveal that the low-coordination and partially unoccupied densities of states of 5d orbital of Pt atoms are responsible for the excellent performance. This work is anticipated to form the basis for the exploration of a next generation of highly efficient single-atom catalysts for various applications.

NH2+ implantations induced superior hemocompatibility of carbon nanotubes

NH2+ implantation was performed on multiwalled carbon nanotubes (MWCNTs) prepared by chemical vapor deposition. The hemocompatibility of MWCNTs and NH2+-implanted MWCNTs was evaluated based on in vitro hemolysis, platelet adhesion, and kinetic-clotting tests. Compared with MWCNTs, NH2+-implanted MWCNTs displayed more perfect platelets and red blood cells in morphology, lower platelet adhesion rate, lower hemolytic rate, and longer kinetic blood-clotting time. NH2+-implanted MWCNTs with higher fluency of 1 × 1016 ions/cm2 led to the best thromboresistance, hence desired hemocompatibility. Fourier transfer infrared and X-ray photoelectron spectroscopy analyses showed that NH2+ implantation caused the cleavage of some pendants and the formation of some new N-containing functional groups. These results were responsible for the enhanced hemocompatibility of NH2+-implanted MWCNTs.

Light-activated covalent formation of gold nanoparticle-graphene and gold nanoparticle-glass composites

Monolayer protected gold nanoparticles (AuNPs) modified with a 3-aryl-3-(trifluoromethyl)diazirine functionality at its terminus (Diaz-AuNPs, 3.9 nm) were prepared and irradiated in the presence of two very different substrates, reduced graphene and glass. Upon irradiation, the terminal diazirine group loses nitrogen to generate a reactive carbene at the interface of the AuNPs that can then undergo addition or insertion reactions with functional groups on the graphene or glass surfaces, leading to the formation of graphene-AuNP and glass-AuNP hybrids, respectively. The AuNP hybrids were characterized using TEM, XRD, XPS, AFM, and UV-vis spectroscopy. Control experiments done in the absence of irradiation demonstrate that carbene activation is required for incorporation of significant AuNP onto the materials. The AuNP hybrids are robust and stable to excessive washing and centrifugation supporting the covalent nature of the interaction between the AuNP and the graphene or silicate glass substrates. Because the formation of the composite is light activated, it lends itself to photopatterning; this application is demonstrated for making the glass-AuNP composites.

Controllable synthesis of graphene-based titanium dioxide nanocomposites by atomic layer deposition

Atomic layer deposition (ALD) was used to synthesize graphene-based metal oxide nanocomposites. This strategy was fulfilled on the preparation of TiO(2)-graphene nanosheet (TiO(2)-GNS) nanocomposites using titanium isopropoxide and water as precursors. The synthesized nanocomposites demonstrated that ALD exhibited many benefits in a controllable means. It was found that the as-deposited TiO(2) was tunable not only in its morphologies but also in its structural phases. As for the former, TiO(2) was transferable from nanoparticles to nanofilms with increased cycles. With regard to the latter, TiO(2) was changeable from amorphous to crystalline phase, and even a mixture of the two with increased growth temperatures (up to 250 °C). The underlying growth mechanisms were discussed and the resultant TiO(2)-GNS nanocomposites have great potentials for many applications, such as photocatalysis, lithium-ion batteries, fuel cells, and sensors.