[Application of island flap and its combined flap on repairing nasal alae defects]

Objective: To evaluate the application of island flap and combined flap in one-stage reconstruction of nasal alae defects after external nasal tumor resection. Methods: Data of 11 patients with perforating or full-thickness defects of the alae after nasal tumor resection in XuanWu Hospital, Capital Medical University between June 2016 and February 2021 were analyzed retrospectively. There were 7 males and 4 females, and the ages ranged from 51 to 89 years. Island flap, island flap combined with nasolabial flap or V-Y advancement flap, and island flap combined with bilobed flap were applied according to the range of defects. Descriptive statistical method was applied to analyze the treatment effects. Results: All flaps of the 11 patients were successful survival and the incisions were primary healing. Being followed up for 5 to 59 months, the patients had satisfying appearance and ventilation function, and no tumor relapsed. Conclusion: For the patients with nasal alae defects after external nose tumor resection, selecting suitable island skin flap or combined skin flap can be used to reconstruct the ideal nasal appearance and function of the nose.

Ti3+ Tuning the Ratio of Cu+ /Cu0 in the Ultrafine Cu Nanoparticles for Boosting the Hydrogenation Reaction

Hydrogenation of diesters to diols is a vital process for chemical industry. The inexpensive Cu⁺ /Cu⁰ -based catalysts are highly active for the hydrogenation of esters, however, how to efficiently tune the ratio of Cu⁺ /Cu⁰ and stabilize the Cu⁺ is a great challenge. In this work, it is demonstrated that doped Ti ions can tune the ratio of Cu⁺ /Cu⁰ and stabilize the Cu⁺ by the TiOCu bonds in Ti-doped SiO₂ supported Cu nanoparticle (Cu/Ti-SiO₂ ) catalysts for the high conversion of dimethyl adipate to 1,6-hexanediol. In the synthesis of the catalysts, the Ti⁴⁺ OCu²⁺ bonds promote the reduction of Cu²⁺ to Cu⁺ by forming Ti³⁺ O_V Cu⁺ (O_V : oxygen vacancy) bonds and the amount of Ti doping can tune the ratio of Cu⁺ /Cu⁰ . In the catalytic reaction, the O vacancy activates CO in the ester by forming new Ti^{3+ δ} O_R Cu^{1+ δ} bonds (O_R : reactant oxygen), and Cu⁰ activates hydrogen. After the products are desorbed, the Ti^{3+ δ} O_R Cu^{1+ δ} bonds return to the initial state of Ti³⁺ O_V Cu⁺ bonds. The reversible TiOCu bonds greatly improve the activity and stability of the Cu/Ti-SiO₂ catalysts. When the content of Ti is controlled at 0.4 wt%, the conversion and selectivity can reach 100% and 98.8%, respectively, and remain stable for 260 h without performance degradation.

[Relations of human papillomavirus infection, vaginal micro-environmental disorder with cervical lesion]

Objective: To study the relations of human papillomavirus (HPV) infection, vaginal micro-environmental disorder with cervical lesion. Methods: A total of 1 019 women including 623 with normal cervical (NC), 303 with low-grade cervical lesion (CIN Ⅰ) and 93 with high-grade cervical lesion (CIN Ⅱ/Ⅲ) were enrolled in this study from the communities in Shanxi province, China. Case-control method was adopted, with NC as the control group and CIN as the case group. Related information was collected including demographic characteristics and relevant factors related to cervical lesions. HPV genotypes were detected by flow-through hybridization technology. Vaginal pH was detected by the pH test paper. Vaginal H(2)O(2) was detected by the combined detection kit of aerobic vaginitis and bacterial vaginosis. Vaginal cleanliness was detected by smear method. Results: Data from the unconditional logistic regression analysis showed that HPV infection (CINⅠ: aOR=1.39, 95%CI: 1.01-1.90; CINⅡ/Ⅲ: aOR=11.74, 95%CI: 6.96-19.80), H(2)O(2) (CINⅠ: aOR=2.09, 95%CI: 1.47-2.98; CINⅡ/Ⅲ: aOR=4.12, 95%CI: 2.01-8.43), cleanliness (CIN Ⅱ/Ⅲ: aOR=2.62, 95%CI: 1.65-4.14), and composite indicators (CINⅠ: aOR=1.67, 95%CI: 1.24-2.25; CINⅡ/Ⅲ: aOR=4.24, 95%CI: 2.30-7.81) all had increased the risk of cervical lesion and the trend on the severity (P<0.001) of cervical lesions. Additionally, we observed a synergic effect between HPV infection and vaginal micro-environmental composite indicator in CINⅡ/Ⅲ. With or without HPV infection, the ORs value of CINⅠ caused by vaginal micro-environment disorder remained close. Conclusions: Results from our study revealed that vaginal micro-environmental composite indicator could increase the risk for cervical lesion, in particular with the high-grade ones which all posed stronger risks when combined with HPV infection. However, the role of vaginal micro-environment disorder in the occurrence of CIN Ⅰ should not be ignored.

Morphologically controlled cobalt oxide nanoparticles for efficient oxygen evolution reaction

Electrochemical water oxidation is one of the thrust areas of research today in solving energy and environmental issues. The morphological control in the synthesis of nanomaterials plays a crucial role in designing efficient electrocatalyst. In general, various synthetic parameters can direct the morphology of nanomaterials and often this is the main driving force for the electrocatalyst in tuning the rate of the oxygen evolution reaction (OER) for the electrochemical water-splitting. Here, a facile and cost-effective synthesis of spinel cobalt oxides (Co₃O₄) via a one-pot hydrothermal pathway with tunable morphology has been demonstrated. Different kinds of morphologies have been obtained by systematically varying the reaction time i.e. nanospheres, hexagon and nanocubes. Their catalytic activity has been explored towards OER in 1.0 M alkaline KOH solution. The catalyst Co₃O₄-24 h nanoparticles synthesized in 24 h reaction time shows the lowest overpotential (η) value of 296 mV at 10 mA cm^-2 current density, in comparison to that of other as-prepared catalysts i.e. Co₃O₄-pH9 (311 mV), Co₃O₄-12 h (337 mV), and Co₃O₄-6 h (342 mV) with reference to commercially available IrO₂ (415 mV). Moreover, Co₃O₄-24 h sample shows the outstanding electrochemical stability up to 25 h time.

[Survey of related factors of maternal venous thromboembolism in nine hospitals of China]

Objective: To investigate and analyze disease status and risk factors of venous thromboembolism (VTE) during pregnancy and puerperium in our country. Methods: Clinical datas were collected from 575 patients diagnosed with VTE during pregnancy and puerperium and hospitalized in nine medical institutions in our country from January 1, 2015 to November 30, 2019, and retrospectively analyzed it's disease status and risk factors. Results: (1) The proportion of VTE in pregnancy and puerperium was 50.6% (291/575) and 49.4% (284/575), respectively. Four patients died, the mortality rate was 0.7% (4/575). The cause of death was pulmonary embolism. (2) The location of VTE during pregnancy and puerperium was mainly in the lower limb vascular (76.2%, 438/575), followed by pulmonary vessels (7.1%, 41/575). (3) In the risk factors of VTE, cesarean section accounted for 32.3% (186/575), maternal advance age accounted for 27.7% (159/575), braking or hospitalization during pregnancy accounted for 13.6% (78/575), other risk factors accounted for more than 5% were previous VTE, obesity, preterm birth, assistant reproductive technology conception and so on, pre-eclampsia and multiple pregnancy accounted for 4.9% (28/575) respectively. In addition, some patients with VTE did not have any of the above risk factors, and the incidence rate was as high as 23.1% (133/575). Conclusions: The occurrence of VTE during pregnancy and puerperium is related to multiple risk factors, and could lead to matemal death, It is very necessary to screen VTE risk factors for all pregnant women, to make corresponding prevention and control measures.

No pulsed radio emission during a bursting phase of a Galactic magnetar

Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances^1-3. It has long been speculated that magnetars are the engine powering repeating bursts from FRB sources^4-13, but no convincing evidence has been collected so far¹⁴. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft γ-ray bursts¹⁵. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft γ-ray/hard-X-ray flare^18-21. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-γ-ray repeater (SGR) bursts were detected in γ-ray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.

Hierarchical Tubular Architecture Constructed by Vertically Aligned CoS2 -MoS2 Nanosheets for Hydrogen Evolution Electrocatalysis

Developing efficient electrocatalysts for the hydrogen evolution reaction (HER) is crucial for establishing a sustainable and environmentally friendly energy system, but it is still a challenging issue. Herein, hierarchical tubular-structured CoS₂ -MoS₂ /C as efficient electrocatalysts are fabricated through a unique metal-organic framework (MOF) mediated self-sacrificial templating. Core-shell structured MoO₃ @ZIF-67 nanorods are used both as a precursor and a sacrificial template to form the one-dimensional tubular heterostructure where vertically aligned two-dimensional CoS₂ -MoS₂ nanosheets are formed on the MOF-derived carbon tube. Trace amounts of noble metals (Pd, Rh, and Ru) are successfully introduced to enhance the electrocatalytic property of the CoS₂ -MoS₂ /C nanocomposites. The as-synthesized hierarchical tubular heterostructures exhibit excellent HER catalytic performance owing to the merits of the hierarchical hollow architecture with abundantly exposed edges and the uniformly dispersed active sites. Impressively, the optimal Pd-CoS₂ -MoS₂ /C-600 catalyst delivers a current density of 10 mA cm^-2 at a low overpotential of 144 mV and a small Tafel slope of 59.9 mV/dec in 0.5 m H₂ SO₄ . Overall, this MOF-mediated strategy can be extended to the rational design and synthesis of other hollow heterogeneous catalysts for scalable hydrogen generation.

Optimizing Electron Densities of Ni-N-C Complexes by Hybrid Coordination for Efficient Electrocatalytic CO2 Reduction

Metal-N-C is a type of attractive electrocatalyst for efficient CO₂ reduction to CO. Because of the ambiguity in their atomic structures, the active sites and catalytic mechanisms of the catalysts have remained under debate. Here, the effects of N and C hybrid coordination on the activity of Ni-N-C catalysts were investigated, combining theoretical and experimental methods. The theoretical calculations revealed that N and C hybrid coordination greatly enhanced the capability of single-atom Ni active sites to provide electrons to reactant molecules and strengthens the bonding of Ni to N and C in the Ni-N-C complexes. During the reaction process, the C and N coordination synergistically optimized the reaction energies in the conversion of CO₂ to CO. A good agreement between theoretical calculations and electrochemical experiments was achieved based on the newly developed Ni-N-C electrocatalysts. The activity of hybrid-coordination NiN₂ C₂ was more than double that of single-coordination NiN₄ .

[The application of Chinese version of anterior skull base questionnaire (ASBQ) in patients with anterior and middle skull base tumors]

Objective: To develop the Chinese version of anterior skull base questionnaire(ASBQ) and to verify its application in patients with anterior and middle skull base tumors. Methods: The following steps were finished including getting the permission from the author of the original English scale, translating and back-translating, tentative test, discussing the consequence and cultural debugging. From October 2016 to December 2018, 51 patients with skull base tumors from Xuanwu Hospital and China-Japan Friendship Hospital were enrolled as an experimental group, aged from 24 to 70 years old, with 19 males and 32 females, which included 27 patients with anterior skull base tumor and 24 patients with middle skull base tumor. From December 2016 to January 2018, 46 healthy volunteers were selected as a control group, aged from 18 to 36 years old, including 26 females and 20 males. The subjects in the test group and the control group were rigorously tested with official manuscripts and judged whether the manuscript was applicable. The SPSS 22.0 statistical software was used to analyze the data of the test group, the anterior skull base group, the middle skull base group and the control group to evaluate the performance of the scale. Results: Both the rate of the recovery and efficiency in experimental group, anterior skull base group and middle skull base group were 100%, with the average time of completion of (8.7±3.2), (11.2±4.0) and (7.3±2.1) min, respectively in each group. The r value of test-retest reliability was 0.96, 0.99 and 0.97 in experimental group, anterior skull base group and middle skull base group, with the split-half reliability coefficient of 0.91, 0.90 and 0.96, with the entire scale Cronbach's coefficient of 0.91, 0.95 and 0.93, respectively. The content validity and the construct validity of the scale were good enough, and the criteria validity was-0.483,-0.509 and -0.489 in experimental group, anterior skull base group and middle skull base group. The scale could well distinguish the difference of the quality of life between the preoperative and postoperative patients in experimental group and the middle skull base group. The difference of the quality of life in anterior skull base group was not found between preoperative and postoperative patients. Conclusion: The Chinese version of ASBQ has good reliability and validity, which is suitable for a wide range of Chinese patients with anterior and middle skull base tumors to assess their quality of life.

[Application of modified Dix-Hallpike maneuver in the diagnosis of posterior semicircular canal benign paroxysmal positional vertigo]

Objective:To investigate the application of modified Dix-Hallpike maneuver in the diagnosis of posterior semicircular canal benign paroxysmal positional vertigo. Method:The modified Dix-Hallpike maneuver, supine roll maneuver and classical Dix-Hallpike maneuver were performed respectively. The sensitivity and specificity of modified and classical Dix-Hallpike maneuver in the diagnosis of posterior semicircular canal BPPV was compared. Result:Fifty-five posterior semicircular canal BPPV patients showed both modified and classical Dix-Hallpike maneuver positive result, including 12 cases of rotational nystagmus induced by ipsilateral supine roll maneuver. Conclusion:Modified Dix-Hallpike maneuver and classical Dix-Hallpike maneuver have the same effect on the diagnosis of posterior semicircular canal BPPV, but the former is easy to the operation, nystagmus observation and result judgment, and is conducive to the promotion of use..

Abnormal methylation of spermatozoa induced by benzo(a)pyrene in rats

Epigenetic mutations caused by pollutants are possibly linked to many diseases. Benzo(a)pyrene (BaP) is one of the most representative air pollutants and has aroused wide concern because of its strong carcinogenicity. The reproductive toxicity induced by BaP has been identified, but little is known about the characteristics of the methylation changes induced by BaP. In this study, a methylated DNA immunoprecipitation sequencing method was used to detect the methylation of sperm DNA of rats exposed to BaP. Compared with the respective genes in normal rats, there were 3227 hypomethylated genes and 828 hypermethylated genes after BaP exposure. Gene ontology enrichment analysis reported that differentially methylated genes (DMGs) were enriched in the localization, single-multicellular organism process and plasma membrane. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that the DMGs were significantly enriched in the Ras signalling pathway, Rap1 signalling pathway, pancreatic secretion and neuroactive ligand-receptor interaction. DisGeNET disease spectrum analysis showed that DMGs were associated with infertility and certain genetic diseases. Further research needs to be done to explore whether these abnormal methylation are transgenerational.

Hollow Functional Materials Derived from Metal-Organic Frameworks: Synthetic Strategies, Conversion Mechanisms, and Electrochemical Applications

Hollow materials derived from metal-organic frameworks (MOFs), by virtue of their controllable configuration, composition, porosity, and specific surface area, have shown fascinating physicochemical properties and widespread applications, especially in electrochemical energy storage and conversion. Here, the recent advances in the controllable synthesis are discussed, mainly focusing on the conversion mechanisms from MOFs to hollow-structured materials. The synthetic strategies of MOF-derived hollow-structured materials are broadly sorted into two categories: the controllable synthesis of hollow MOFs and subsequent pyrolysis into functional materials, and the controllable conversion of solid MOFs with predesigned composition and morphology into hollow structures. Based on the formation processes of hollow MOFs and the conversion processes of solid MOFs, the synthetic strategies are further conceptually grouped into six categories: template-mediated assembly, stepped dissolution-regrowth, selective chemical etching, interfacial ion exchange, heterogeneous contraction, and self-catalytic pyrolysis. By analyzing and discussing 14 types of reaction processes in detail, a systematic mechanism of conversion from MOFs to hollow-structured materials is exhibited. Afterward, the applications of these hollow structures as electrode materials for lithium-ion batteries, hybrid supercapacitors, and electrocatalysis are presented. Finally, an outlook on the emergent challenges and future developments in terms of their controllable fabrications and electrochemical applications is further discussed.

[Analysis of labor progression characteristics of 1 089 nulliparas managed by the new partogram]

Objective: To analyze labor progression characteristics among nulliparas and provide reference to labor progress management. Methods: A retrospective study was conducted on 1 089 women who went for vaginal delivery at the First Affiliated Hospital, Sun Yet-San University from January 1st, 2015 to May 31th, 2016. The duration of cervical dilation from 1.0 cm to the next and the process of initial cervical dilation (2.0 cm or 3.0 cm) to full cervical dilation of nulliparas were analyzed. Results: The cervical dilation speed was accelerating with the progress of labor. The rate of cervical dilation changed fastest between 5.0-6.0 cm dilation, which was more than 3.0 cm/hour. With regard to labor curves, at admission of 2.0 cm cervical dilation, it rose dramatically from 5.0 cm dilation. At admission of 3.0 cm dilation, it presented approximately linear rising before 5.5 cm dilation, then became steeper. Conclusions: The cervical dilation speed is fast. Both labor curves of initial cervical dilation (2.0 cm or 3.0 cm) to full cervical dilation show obvious acceleration stage with steep slope.

Tailored synthesis of Zn-N co-doped porous MoC nanosheets towards efficient hydrogen evolution

Developing non-precious metal catalysts with both high efficiency and long-term stability is the top priority for hydrogen evolution reactions (HER). Herein, we present a facile two-step method to synthesize Zn, N co-doped molybdenum carbide nanosheets (Zn-N-MoC-H NSs) by using bi-metal oxides of ZnMoO4 as a unique precursor. Zn not only serves as a template to form a porous structure on MoC nanosheets during volatilizing at high temperatures, but also acts as a doping source for Zn doping in MoC. The N-containing carbon source realizes N doping of MoC. Benefitting from Zn, N co-doping and the porous nanosheet structure with a large electrochemical surface area, Zn-N-MoC-H NSs lead to enhanced HER activity in an acidic electrolyte (0.5 M H2SO4) with a low onset potential of -66 mV vs. RHE (1 mA cm-2), overpotential of 128 mV (10 mA cm-2), small Tafel slope of 52.1 mV dec-1 and persistent long-term stability. Density functional theory calculations reveal that Zn, N co-doping can synergistically weaken the strong Mo-H bonding, improve absorbed hydrogen atom (Hads) desorption and lead to faster HER kinetics. This study provides new insights into the use of Zn as a template and electronic regulator toward efficient catalysis and applications in energy storage and conversion.

[Risk factors, diagnosis and treatment of peri-implant diseases]

With the wide spread of dental implantation, more and more soft and hard tissue illness related to dental implants occurred. According to a statistical analysis, about 1/4 to 1/2 patients are under the risk of suffering from peri-implant diseases. Peri-implant diseases include peri-implant mucotitis and peri-implantitis. The former is connected with soft tissue while the latter is related to hard tissue around dental implant. This article reviews the diagnosis, classification and treatment of peri-implant diseases.

[Establishment and characterization of an orthotopic murine model of mucosal malignant melanoma of the maxillary sinus]

Objective:To establish a stable and reliable orthotopic murine model of mucosal malignant melanoma of the maxillary sinus so as to provide animal models for further studying for pathogenesis and therapy of sinonasal malignancy.Method:B16 were implanted in the right maxillary sinus of male nude mice. After tumors appeared in right maxillary sinus, tumor growth and survival rate were recorded. The degree of tumor infiltration was observed through the MRI.Result:Mice with B16 implanted in right maxillary sinus developed primary tumors. The survival and the tumor volume were related to the number of tumor cells implanted. We found that the tumor can invade into nasal cavity, orbital cavity and the basilar region using MRI.Conclusion:We successfully established a model for mucosal malignant melanoma of the maxillary sinus. This model offers an experimental tool for further research on biological characteristics of sinonasal malignancy and the development of new therapy.

[The impact of resection of skull base tumor via an endoscopic endonasal approach on the visual function of vision impaired patients and the analysis of factors affecting their visual recovery]

Objective: To evaluate the visual outcomes of patients with visual impairment after resecting skull base tumor via an endoscopic endonasal approach, and to analyze the factors affecting visual recovery. Methods: One hundred and fifty-three patients with skull base tumor who suffered from preoperative visual impairment from Skull Base Surgery Center of Xuanwu Hospital were operated through an endoscopic endonasal approach. Both preoperative and postoperative visual function outcomes as well as factors that might have affected their visual recovery were analyzed retrospectively by Chi square test and Logistic regression analysis. Results: Complete resection was achieved in 85.6% of the patients using this technique. The rate of postoperative visual recovery in the female group (86.1%) was higher than that in the male group (73.9%), the benign group (90.2%) higher than the malignant group (20.0%), the group without optic atrophy (97.1%) higher than the one with (51.2%), and the acute group (96.6%) higher than the chronic group (80.0%). Significant differences were found between the abovementioned groups (χ(2) value was 5.849, 87.860, 79.757, 4.745, respectively, all P<0.05). The degree of optic atrophy and the property of tumors were significantly associated with visual improvement after treatment (Wold χ(2) value was 18.597 and 35.623, all P<0.001). Conclusions: Our results indicate that endoscopic endonasal surgery shows its ability both to resect skull base tumors and to improve visual function in the majority of patients. The timing of treatment for patients suffered from preoperative visual impairment should be selected in early stage before optic atrophy occurs.

Commentary on "A novel treatment strategy for newly diagnosed high-grade T1 bladder cancer: Gemcitabine and cisplatin adjuvant chemotherapy-A single-institution experience."

BACKGROUND

Management of high-grade T1 (formerly T1G3) bladder cancer continues to be controversial. Should patients with T1G3 bladder cancer have an immediate radical cystectomy or should they receive intravesical bacillus Calmette-Guérin preserving bladder? Gemcitabine and cisplatin (GC) adjuvant chemotherapy may help to strike a balance between intravesical and early cystectomy. For purposes of this study, we continue to refer high-grade T1 lesion as "T1G3."

OBJECTIVE

To evaluate the characteristics and the long-term outcome of GC adjuvant chemotherapy in T1G3 bladder cancer after transurethral resection of bladder tumor (TURBT).

MATERIALS AND METHODS

We, retrospectively, reviewed 48 patients who were newly diagnosed with T1G3 bladder cancer between January 2009 and December 2012. A total of 48 patients received 4 cycles of GC adjuvant chemotherapy after TURBT. One month after 4 cycles of GC adjuvant chemotherapy, response was evaluated by re-TURBT. Median follow-up was 59.5 (range: 18-70) months, all patients have been observed for more than 3 years. Salvage cystectomy was recommended for patients with persistent disease and for tumor progression after initial complete response.

RESULT

Complete response was achieved in 44 (91.7%) patients. Of complete responders, 5 patients experienced recurrence and 5 patients showed progression. The progression rate and disease-specific survival rate were 10.4% and 91.7% at 3 years, respectively. More than 80% of survivors preserved their bladder. Kaplan-Meier curves showed that concomitant carcinoma in situ (CIS) was the only factor that had an influence on progression-free survival (P = 0.022) and disease-specific survival (P = 0.017). Concomitant CIS was the prognostic factor for progression rate and disease-specific survival rate at 3 years (P = 0.008 and P = 0.035).

CONCLUSION

GC adjuvant chemotherapy is a safe conservative treatment for T1G3 bladder cancer, but effective is really a phase II study. Patients with T1G3 bladder cancer with concomitant CIS should be treated more aggressively because of the high risk of progression.

Facile Synthesis of Palladium-Nanoparticle-Embedded N-Doped Carbon Fibers for Electrochemical Sensing

In recent years, there have been many studies on metal/carbon hybrid materials for electrochemical applications. However, reducing the metal content in catalysts is still a challenge. Here, a facile synthesis of palladium (Pd) nanoparticle-embedded N-doped carbon fibers (Pd/N-C) through electropolymerization and reduction methods is demonstrated. The as-prepared Pd/N-C contains only 1.5 wt % Pd. Under optimal conditions, bisphenol A is detected by using amperometry in two dynamic ranges from 0.1 to 10 μm and from 10 to 200 μm, and the obtained correlation coefficients are close to 0.9836 and 0.9987, respectively. The detection limit (DL) for bisphenol A is determined to be 29.44 (±0.77) nm.

Highly sensitive flexible three-axis tactile sensors based on the interface contact resistance of microstructured graphene

The lack of high-performance tactile sensors, especially for pressure/force, is a huge obstacle for the widespread application of intelligent robots. Current pressure sensors are often operated in the high range of pressure and normal direction, showing a little ability in the low range of pressure and three-axis direction simultaneously. Herein, a highly sensitive flexible tactile sensor with three-axis force sensing capacity is presented by combining microstructured polydimethylsiloxane (PDMS) arrays and a reduced graphene oxide (rGO) film. The deformation of microstructured rGO/PDMS results in a change in the contact area between the rGO film and electrode, leading to a high sensitivity of -1.71 kPa-1 in the low range pressure of 0-225 Pa with a fast response time of 6 ms at a large feature size of 100 μm. To realize three-axis sensing, a sensing unit was built up, which was composed of the adjacent four parts of patterns and electrodes underneath a bump. A mechanical model of the exerted spatial force was established to calculate each axis force component via the deformation of the rGO/PDMS pattern. The experimental results show that the current difference between the adjacent two parts has a strong relationship with the applied force. As a proof of concept, we have demonstrated a 3 × 3 array sensor for arbitrary force sensing. Our tactile sensor would be used in transmitting information from a gentle spatial force and would exhibit broad applications as e-skin in integrated robots.

Spatially Confined Assembly of Monodisperse Ruthenium Nanoclusters in a Hierarchically Ordered Carbon Electrode for Efficient Hydrogen Evolution

The redox units of polyaniline (PAni) are used cooperatively, and in situ, to assemble ruthenium (Ru) nanoclusters in a hierarchically ordered carbon electrode. The oxidized quinonoid imine (QI) units in PAni bond Ru complex ions selectively, whereas reduced benzenoid amine (BA) units cannot. By electrochemically tuning the ratio of QI to BA, Ru complexes are spatially confined in the outer layer of hierarchical PAni frameworks. Carbonization of Ru-PAni hybrids induces nucleation on the outer surface of the carbon support, generating nearly monodisperse Ru nanoclusters. The optimized catalyst has a low loading of approximately 2 wt % Ru, but exhibits a mass activity for the hydrogen evolution reaction that is about 6.8 times better than commercial 20 wt % Pt/C catalyst.