Single atom catalysts: a surface heterocompound perspective

The concept of single atom catalysts (SACs) originated from reducing the amount of noble metals used, by steadily refining the particle size loaded on a substrate surface. It has been rapidly moving to non-noble elements and their compounds in recent years, notably transition metals and even non-metals. They are of heterogeneous types, where the active species are refined to atomic dispersion scales on the surfaces/sub-surfaces of the solid support. The catalytic performance is governed by both the type and population of accessible active sites, and their bond and coordination environment, largely as a result of the interactions with the substrate surface. Unlike the internal structure within a crystalline solid, there is a large spatial variation in the bond and coordination environment of different atoms on the solid surface across different length scales, and in particular with the unsaturated surface, where there are various defects. They can also be dramatically altered during both the catalyst synthesis and actual catalysis process. In a way, they form a "surface heterocompound", where the local bonds for each metal atom are of a compound type, while there can be a large variation from one to another. Herein, we will look into the evolution from traditional heterogeneous catalysts to SACs, from the surface heterocompound perspective. Discussion will then be made on the on-going strategies and challenges in manipulating and identifying the local bond and coordination environment on the hetero-surfaces, in an attempt to develop efficient catalysts for the targeted applications, where both synthesis techniques and analytical tools are critically important, and computational studies can provide the key guiding principles. With selected paradigm studies, we will briefly examine the future perspectives for this newly emerging catalysis frontier.

Assembling of Bi atoms on TiO2 nanorods boosts photoelectrochemical water splitting of semiconductors

Low photoconversion efficiency, high charge transfer resistance and fast recombination rate are the bottlenecks of semiconductor nanomaterials in photoelectrochemical (PEC) water splitting, where the introduction of an appropriate co-catalyst is an effective strategy to improve their performance. In the present study, we have purposely designed atomic-scale dispersed bismuth (Bi) assembled on titanium dioxide nanorods (TiO2), and demonstrated its effective role as a co-catalyst in enhancing the PEC water splitting performance of TiO2. As a result, functionalized Bi/TiO2 generates a high photocurrent intensity at 1.23 VRHE under simulated solar light irradiation, which is 4-fold higher than that of pristine TiO2, exhibiting a significantly improved PEC performance for water splitting. The strategy presented in this study opens a new window for the construction of non-precious metals dispersed at atomic scales as efficient co-catalysts for realizing sustainable solar energy-driven energy conversion and storage.

Twinned Tungsten Carbonitride Nanocrystals Boost Hydrogen Evolution Activity and Stability

Synergistic integration of two active metal-based compounds can lead to much higher electrocatalytic activity than either of the two individually, due to the interfacial effects. Herein, a proof-of-concept strategy is creatively developed for the successful fabrication of twinned tungsten carbonitride (WCN) nanocrystals, where W₂ C and WN are chemically bonded at the molecule level. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption fine structure (XAFS) spectroscopy analyses demonstrate that the intergrowth of W₂ C and WN in the WCN nanocrystals produces abundant N-W-C interfaces, leading to a significant enhancement in catalytic activity and stability for hydrogen evolution reaction (HER). Indeed, it shows 14.2 times higher and 140 mV lower in the respective turn-over frequency (TOF) and overpotential at 10 mA cm^-2 compared to W₂ C alone. To complement the experimental observation, the theoretical calculations demonstrate that the WCN endows more favorable hydrogen evolution reaction than the single W₂ C or WN crystals due to abundant interfaces, beneficial electronic states, lower work function, and more active W sites at the N-W-C interfaces.

Strong Charge Transfer at 2H-1T Phase Boundary of MoS2 for Superb High-Performance Energy Storage

Transition metal dichalcogenides exhibit several different phases (e.g., semiconducting 2H, metallic 1T, 1T') arising from the collective and sluggish atomic displacements rooted in the charge-lattice interaction. The coexistence of multiphase in a single sheet enables ubiquitous heterophase and inhomogeneous charge distribution. Herein, by combining the first-principles calculations and experimental investigations, a strong charge transfer ability at the heterophase boundary of molybdenum disulfide (MoS₂ ) assembled together with graphene is reported. By modulating the phase composition in MoS₂ , the performance of the nanohybrid for energy storage can be modulated, whereby remarkable gravimetric and volumetric capacitances of 272 F g^-1 and 685 F cm^-3 are demonstrated. As a proof of concept for energy application, a flexible solid-state asymmetric supercapacitor is constructed with the MoS₂ -graphene heterolayers, which shows superb energy and power densities (46.3 mWh cm^-3 and 3.013 W cm^-3 , respectively). The present work demonstrates a new pathway for efficient charge flow and application in energy storage by engineering the phase boundary and interface in 2D materials of transition metal dichalcogenides.

Flexible and Wearable All-Solid-State Al-Air Battery Based on Iron Carbide Encapsulated in Electrospun Porous Carbon Nanofibers

In this work, electrospinning N-doped carbon nanofibers containing iron carbide (Fe₃C@N-CFs) are synthesized and employed as the cathode in the flexible Al-air battery. Benefiting from the excellent catalytic activity of the iron carbide which is uniformly encapsulated in the N-doped carbon matrix, as well as the large specific surface area of the cross-linked network nanostructure, the as-prepared Fe₃C@N-CFs show outstanding catalytic activity and stability toward oxygen reduction reaction. The as-fabricated all-solid-state Al-air batteries with Fe₃C@N-CF catalyst show a stable discharge voltage (1.61 V) for 8 h, giving a capacity of 1287.3 mA h g^-1.

A comparative study of proximal femoral locking compress plate, proximal femoral nail antirotation and dynamic hip screw in intertrochanteric fractures

OBJECTIVE

We aimed to compare the clinical efficacy of three different internal fixation methods, i.e. proximal femoral locking compress plate (PF-LCP), proximal femoral nail antirotation (PFNA) and dynamic hip screw (DHS) system in intertrochanteric femur fracture.

PATIENTS AND METHODS

We selected a total of 150 patients with Intertrochanteric femur fracture who were admitted to this hospital between January 2015 and December 2016 for treatment, and those patients were divided into three groups according to the difference in treatment methods, i.e., Group A (n=50), Group B (n=50) and Group C (n=50). For patients in Group A, they received the PF-LCP treatment, patients in Group B received PFNA treatment while those in Group C received DHS treatment; ultimately, clinical efficacy was compared among three groups.

RESULTS

In Group B, the efficacy was superior to those in Group A and C in terms of comparison of surgical duration, bleeding amount, time point of callus formation, healing time of fracture and length of stay (LOS) in hospital (p<0.05); after operation, the prevalence rate of complication in Group B was significantly lower than those in Group A and Group C (p<0.05); in comparison of preoperative Harris score among three groups, the different had no statistical significance (p>0.05). The Harris scores in Group B at the 1st, 3rd, and 6th month after operation were all significantly higher than those in Group A and C (p<0.05).

CONCLUSIONS

Compared with PF-LCP and DHS, PFDA can better fix the intertrochanteric femur fracture with little effect on blood circulation at the fracture end and slight damage to sclerotin, thereby accelerating the recovery of hip joint function without any increase in prevalence of complications. Therefore, PFDA has a promising clinical efficacy and safety, which is worthy of being promoted in clinical practice.

Regulation network analysis in the esophageal squamous cell carcinoma

BACKGROUND

The incidence of esophageal squamous cell carcinoma (ESCC) has high regional selectivity. The molecular mechanisms of ESCC are complex and involve multiple oncogenes, tumor suppressor genes, receptor tyrosine kinases, cytoplasmic enzymes, and tumor interstitial elements.

AIM

Here we used bioinformatics to obtain some important genes and pathways involved in ESCC.

MATERIALS AND METHODS

In this article, we did Affymetrix microarray data collection from three big databases, and then selected all the differentially expressed genes (DEGs) according to some principles. On this basis, we carried out regulation network analysis and pathway enrichment analysis, obtaining ESCC related regulation network analysis, after which we selected significant pathways on regulation network and established TF-pathway regulation network.

RESULTS

In the transcription factors (TFs) regulation network we found SP1, E2F1, USF2 and SP3 form a local network which suggested that these TFs might play a more important role in ESCC. Some key pathways were also identified, such as P53 signaling pathway, melanoma and prostate cancer pathways.

CONCLUSIONS

The identification of crucial molecular pathways involved in ESCC would ultimately improve therapeutic effects and facilitate the development of new treatment strategies.

Bioinformatics analysis of two microarray gene-expression data sets to select lung adenocarcinoma marker genes

BACKGROUND

Lung adenocarcinoma (LAC) is the most frequent histologic type of lung cancer and rates of adenocarcinoma are increasing in most countries. Recently, several molecular markers have been identified to predict LAC. However, more prognostic makers and the underlying role of those makers are still imperative.

AIM

In this study, our objective was to identify a set of discriminating genes that can be used for characterization and prediction of response to LAC.

MATERIALS AND METHODS

Using the bioinformatics analysis method, we merged two LAC datasets-GSE2514 and GSE7670 to find novel target genes and pathways to explain the pathogenicity.

RESULTS

The results showed that EDNRB (endothelin receptor type B), ADRB2 (beta-adrenergic receptor), S1PR1 (sphingosine-1-phosphate receptor 1), P2RY14 (PsY purinoceptor 14), LEPR (leptin-receptor), GHR (growth hormone receptor), PPM1D (protein phosphatase-1D), and GADD45B (growth arrest and DNA-damage-inducible, beta) have high degrees in response to LAC. Additionally, EDNRB, ADRB2, S1PR1, P2RY14, LEPR, and GHR may be involved in LAC through Neuroactive ligand-receptor interaction, but PPM1D and GADD45B may be through p53 signaling pathway. Some of our prediction had been demonstrated by previous reports, such as ADRB2, S1PR1, GHR, PPM1D, and GADD45B. Therefore, we hope our study could lay a basis for further study of other target genes, such as EDNRB, P2RY14, and LEPR.

CONCLUSIONS

It is effective to identify potential molecular marker for LAC and predict their underlying functions by bioinformatics analysis and graph clustering method. However, further experiments are still indispensable to confirm our conclusion.

Bioinformatics analysis reveals potential candidate drugs for psychological stress in ovarian cancer

BACKGROUND

Women with ovarian cancer may be at increased risk for psychological distress around the time of diagnosis relative to patients diagnosed with other cancers, because of the seriousness of the disease. However, the molecular mechanism of this effect is far from clear.

AIM

We sought to investigate the influence of psychological status in regulating gene expression among women with primary ovarian cancer and to identify the small molecules which exhibit similar effects with different psychological status.

MATERIALS AND METHODS

DNA microarray analyses of 10 ovarian carcinomas (GSE9116, downloaded from GEO) identified 916 human transcripts that were differentially expressed in tumors from patients with high depression relative to grade-and stage-matched tumors from low depression patients, and pathways related to immune system were dysfunctional.

RESULTS

Our results suggest that psychosocial stress is related to impaired immunity in ovarian cancer patients. Besides, we identified a group of small molecules which can be exploited as adjuvant drug to improve therapeutic effect for ovarian cancer, such as MS-275 and adiphenine.

CONCLUSIONS

Our findings may be useful for the development of management strategies for psychological distress, and we suggest that there is a need for improvement in the quality of life of cancer outpatients being treated with chemotherapy.

[Risk of cerebrovascular disease incidence in the cohort of Mayak production association workers first employed during 1948-1958]

Incidence of cerebrovascular diseases (CVD) has been studied in a cohort of 12210 workers first employed at one of the main plants (reactors, radiochemical or plutonium) of the Mayak nuclear facility during 1948-1958 and followed up to the end of 2000. Information on external gamma doses is available for virtually all (99.9%) of these workers; the mean (+/- one standard deviation) total gamma dose was 0.91 +/- 0.95 Gy (99% percentile 3.9 Gy) for men and 0.65 +/- 0.75 Gy (99% percentile 2.99 Gy) for women. Plutonium body burden was measured only for 30.0% of workers. Amongst those monitored, the mean (+/- standard deviation) cumulative liver dose from plutonium alpha exposure was 0.40 +/- 1.15 Gy (99% percentile 5.88 Gy) for men and 0.81 +/- 4.60 Gy (99% percentile 15.95 Gy) for women 4418 cases (first diagnosis) of CVD were identified in the studied cohort. A statistically significant increasing trend in CVD incidence with total external gamma dose was revealed after adjustment for non-radiation factors and internal exposure from incorporated plutonium-239. Excess relative risk per Gy was 0.464 (95% confidence interval 0.360-0.567). Incidence of CVD was statistically significantly higher for the workers chronically exposed to external gamma rays at a dose above 1.0 Gy A statistically significant increasing trend in CVD incidence with internal liver dose from plutonium alpha exposure was observed after adjustment for non-radiation factors and external exposure. ERR per Gy was 0.155 (95% confidence interval 0.075-0.235). CVD incidence was statistically significantly higher among workers with a plutonium liver dose above 0.1 Gy, although the trend estimates differed between workers at different plants. The incidence risk estimates for external radiation are generally compatible with estimates from the study of Chernobyl clean-up workers, although the incidence data point to higher risk estimates compared to those from the Japanese A-bomb survivors.

The influence of level of feeding on growth and serum insulin-like growth factor I and insulin-like growth factor-binding proteins in growing beef cattle supplemented with somatotropin

The objective of this study was to determine the effects of level of feeding on growth, feed efficiency (gain:feed; G:F), body composition (BC), and serum concentrations of somatotropin (ST), IGF-I, and IGF-binding proteins (BP) in growing beef cattle supplemented with bovine (b) ST. In each of two consecutive years, 40 growing beef cattle were blocked by weight (average BW: yr 1 = 316 kg, yr 2 = 305 kg) and used in a 2 x 2 factorial arrangement with main effects of bST (0 or 33 microg x kg BW(-1) x d(-1)) and level of feed intake (ad libitum [AL] or 0.75 AL). Relative to uninjected cattle, treatment with bST increased ADG 9.6% (1.14 vs 1.25 kg/d; P < 0.05) and increased G:F 8.1% (12.3 vs 13.3 gain [g]:feed [kg]; P < 0.05), whereas ADG in AL animals was 39% greater than that in 0.75 AL animals (1.39 vs 1.00 kg/d; P < 0.05). There was a tendency (P = 0.10) for a bST x level of feeding interaction, such that the increase in ADG with bST was greater in AL cattle than in 0.75 AL cattle (10.6 vs 7.8%; P = 0.10). Serum concentrations of ST were greater in 0.75 AL cattle than in AL cattle (13.0 vs 8.6 ng/mL; P < 0.05) and in bST-treated cattle than in uninjected cattle (16.3 vs 5.2 ng/mL; P < 0.05). Due to a bST x level of feeding interaction (P < 0.01), the magnitude of the increase in serum ST to exogenous bST was greater (P < 0.01) in 0.75 AL cattle than in AL cattle. Relative to uninjected cattle, treatment with bST increased (P < 0.05) serum concentrations of IGF-I and IGFBP-3 and reduced (P < 0.05) concentrations of IGFBP-2. Similarly, AL cattle had greater (P < 0.05) serum concentrations of IGF-I and IGFBP-3 and reduced (P < 0.05) IGFBP-2 compared with 0.75 AL cattle. In summary, treatment with bST increased growth rate and G:F and stimulated serum IGF-I and IGFBP-3 while reducing IGFBP-2. Feeding at 0.75 ad libitum intake reduced the magnitude of response for each of these variables. Thus, limit-feeding may reduce the effect of exogenous bST on growth rate by blunting bST-induced increases in IGF-I and IGFBP-3 and bST-induced decreases in IGFBP-2.

[Thrombopoietic effect of recombinant human thrombopoietin gene transferred to mice mediated by electric pulse on normal and experimental thrombocytopenia mice]

OBJECTIVE

To investigate the thrombopoietic effect of recombinant human thrombopoietin (rhTpo) gene transferred by electric pulse to normal and experimental thrombocytopenia mice.

METHODS

Eukaryotic high expressing plasmid pcDI/Tpo was constructed by gene recombinant technology. 200 microg of the recombinant plasmid was injected into quadriceps femoris muscle of normal and experimental thrombocytopenia mice. Six times of electric pulse at 100v, 1Hz, 40ms were given immediately after the injection.The expression of rhTpo gene and its protein were assayed by RT-PCR and Western Blotting, respectively. Serum Tpo concentration was assayed by ELISA method.

RESULTS

The recombinant plasmid pcDI/Tpo was successfully constructed. The expression of mRNA and protein of rhTpo gene was detected in the skeletal muscle of mice after transfection. Serum Tpo level increased from 328 +/- 89 ng/L to 1185 +/- 264 ng/L, and the platelet level of transfected mice increased from (259 +/- 27) x 10(9)/L to (640 +/- 31) x 10(9)/L. After injection with carboplatin, the platelet level decreased, but the nadir point was higher in pcDI/Tpo group than that in control group, and the recovery time of platelet count in pcDI/Tpo group shortened.

CONCLUSION

The rhTpo gene could be effectively transfected to mice by electric pulse and played thrombopoietic role in vivo.

Expression and functional characterization of the cardiac muscle ryanodine receptor Ca(2+) release channel in Chinese hamster ovary cells

To study the function and regulation of the cardiac ryanodine receptor (RyR2) Ca(2+) release channel, we expressed the RyR2 proteins in a Chinese hamster ovary (CHO) cell line, and assayed its function by single channel current recording and confocal imaging of intracellular Ca(2+) ([Ca(2+)](i)). The 16-kb cDNA encoding the full-length RyR2 was introduced into CHO cells using lipofectAmine and electroporation methods. Incorporation of microsomal membrane vesicles isolated from these transfected cells into lipid bilayer membrane resulted in single Ca(2+) release channel activities similar to those of the native Ca(2+) release channels from rabbit cardiac muscle SR membranes, both in terms of gating kinetics, conductance, and ryanodine modification. The expressed RyR2 channels were found to exhibit more frequent transitions to subconductance states than the native RyR2 channels and RyR1 expressed in CHO cells. Caffeine, an exogenous activator of RyR, induced release of [Ca(2+)](i) from these cells. Confocal imaging of cells expressing RyR2 did not detect spontaneous or caffeine-induced local Ca(2+) release events (i.e., "Ca(2+) sparks") typically seen in cardiac muscle. Our data show that the RyR2 expressed in CHO cells forms functional Ca(2+) release channels. Furthermore, the lack of localized Ca(2+) release events in these cells suggests that Ca(2+) sparks observed in cardiac muscle may involve cooperative gating of a group of Ca(2+) release channels and/or their interaction with muscle-specific proteins.

[Long-term results of surgical treatment of intractable Menière's disease for control of vertigo]

OBJECTIVE

To acquire the long-term (an average of over 10 years follow-up) results of surgical treatment of patients with Meniere's disease for control of vertigo.

METHOD

Endolymphatic sac surgery was done in 6 cases (1 case of endolymphatic sac decompression and 5 cases of sac-mastoid shunting) and translabyrinth vestibular neurotomy was operated on 6 cases.

RESULT

Complete relief from symptoms of vertigo occurred in the 6 cases through vestibular neurotomy and there were no recurrence in 11-13 years follow-up. Three of 6 cases with endolymphatic sac surgery had complete control of vertigo and were cured clinically. Symptoms of vertigo of the rest 3 cases were effectively controlled.

CONCLUSION

Endolymphatic sac surgery and translabyrinth vestibular neurotomy are effective way for control of vertigo of patients with intractable Meniere's disease. Translabyrinth vestibular neurotomy are more effective for control of vertigo for appropriately selected patients.

Caffeine-induced release of intracellular Ca2+ from Chinese hamster ovary cells expressing skeletal muscle ryanodine receptor. Effects on full-length and carboxyl-terminal portion of Ca2+ release channels

The ryanodine receptor (RyR)/Ca2+ release channel is an essential component of excitation-contraction coupling in striated muscle cells. To study the function and regulation of the Ca2+ release channel, we tested the effect of caffeine on the full-length and carboxyl-terminal portion of skeletal muscle RyR expressed in a Chinese hamster ovary (CHO) cell line. Caffeine induced openings of the full length RyR channels in a concentration-dependent manner, but it had no effect on the carboxyl-terminal RyR channels. CHO cells expressing the carboxyl-terminal RyR proteins displayed spontaneous changes of intracellular [Ca2+]. Unlike the native RyR channels in muscle cells, which display localized Ca2+ release events (i.e., "Ca2+ sparks" in cardiac muscle and "local release events" in skeletal muscle), CHO cells expressing the full length RyR proteins did not exhibit detectable spontaneous or caffeine-induced local Ca2+ release events. Our data suggest that the binding site for caffeine is likely to reside within the amino-terminal portion of RyR, and the localized Ca2+ release events observed in muscle cells may involve gating of a group of Ca2+ release channels and/or interaction of RyR with muscle-specific proteins.

Performance evaluation of a Scheimpflug stereocamera for particle image velocimetry

We describe a novel stereocamera for particle image velocimetry (PIV) applications that incorporates the Scheimpflug condition that the object plane, lens plane, and image plane must be collinear. We examined the governing equations for this system using a computer-based sensitivity analysis to predict the accuracy of the in-plane and out-of-plane measurement. We evaluated the performance of the Scheimpflug PIV system with a three-dimensional uniform translation test. Results indicate that the Scheimpflug PIV stereocamera performs as expected. The larger off-axis angles possible with the Scheimpflug system can provide a higher accuracy in the out-of-plane component when compared with a translation PIV stereocamera.