光电催化析氧和CO_(2)还原反应催化剂的研究进展

随着日益增加的化石能源消耗和环境污染,新能源和环境友好型技术的应用对工业发展发挥着重要作用.利用太阳能及电能进行各种催化反应的光电催化(PEC)是一种有应用前景的技术,与传统催化技术相比,具有环保节能、效率高的优势.析氧反应(OER)和CO_(2)还原反应(CO_(2)RR)是两种具有能源及环境应用潜力的催化反应.PECOER对基于水氧化和其他相关氧化反应的可再生能源技术具有重要作用.PEC CO_(2)RR可以将CO_(2)转化为高附加值化学品,实现CO_(2)的合理利用.上述两种技术均具有较大的研究价值和应用前景.本综述首先阐述了电催化和光催化技术的优缺点.由于工业上使用电催化技术会消耗煤和石油等化石能源,有污染环境的风险,且长期的用电成本会影响最终的盈利;而使用光催化技术又面临着反应效率不理想、稳定性差和可见光吸收率低等缺点.一方面,PEC技术可以解决光催化中光生电子-空穴对复合速度快、反应时间长的缺点;另一方面,PEC技术可以降低电催化过程中在高电流密度下反应所需的过电位,在节省电能的同时提高反应效率.此外,系统地介绍了光电催化产氧和CO_(2)RR的机理和参数、催化剂类型、评价标准以及近年来的研究进展.对于反应条件,光电催化和电催化所使用的基础仪器基本相同,而光电催化是在电催化的基础之上施加外部光源,利用光能进一步提高反应效率和稳定性.光电催化和电催化的反应机理也基本一致,不同的是光电催化的评价标准与电催化有所不同.在光照作用下,除了关注特定电压下的电流密度、选择性和稳定性外,研究者们更关注应用偏压光子电流转换效率(ABPE)和入射光子对电流的效率(IPCE)的影响.同时,介绍了用于PEC OER和CO_(2)RR催化剂的类别、优势、合成方法、设计原则和改性策略.就目前研究而言,光电催化性能优异的催化剂一般都具有导电性良好、光吸收效率高和载流子分离速率快等特点.随着对光电催化技术研究地深入,通过掺杂、制造缺陷、设计异质结、负载单/双原子和改变反应微环境等方法有效地提升了催化效率和稳定性.在上述研究基础上,还扩展性地阐述光热催化、光酶催化等近几年的热点技术,这些技术均具有反应条件温和、过程简单和效率高等特点,在未来具有较大的研究价值.最后,展望了PEC技术的未来发展趋势和前景,重点关注了它在工业上的应用前景和价值.在未来,PEC技术将朝着智能化、创新和环保的方向发展.通过先进的理论技术(如理论计算、机器学习、分子动力学模拟等)和原位表征探索反应机理,实现低成本、绿色和智能化的技术以迎接未来实现大规模工业化的挑战,从而在盈利和环保两者之间实现“双赢”.希望本文能帮助读者更快及更全面地了解PEC技术的基本原理、常用催化剂、改性策略、拓展技术、应用前景和发展趋势,从而为读者提供可借鉴的研究思路.

Transition from a filamentary mode to a diffuse one with varying distance from needle to stream of an argon plasma jet

Plasma jet has extensive application potentials in various fields, which normally operates in a diffuse mode when helium is used as the working gas. However, when less expensive argon is used, the plasma jet often operates in a filamentary mode. Compared to the filamentary mode, the diffuse mode is more desirable for applications. Hence, many efforts have been exerted to accomplish the diffuse mode of the argon plasma jet. In this paper, a novel single-needle argon plasma jet is developed to obtain the diffuse mode. It is found that the plasma jet operates in the filamentary mode when the distance from the needle tip to the central line of the argon stream(d) is short. It transits to the diffuse mode with increasing d. For the diffuse mode, there is always one discharge pulse per voltage cycle, which initiates at the rising edge of the positive voltage. For comparison, the number of discharge pulse increases with an increase in the peak voltage for the filamentary mode. Fast photography reveals that the plasma plume in the filamentary mode results from a guided positive streamer,which propagates in the argon stream. However, the plume in the diffuse mode originates from a branched streamer, which propagates in the interfacial layer between the argon stream and the surrounding air. By optical emission spectroscopy,plasma parameters are investigated for the two discharge modes, which show a similar trend with increasing d. The diffuse mode has lower electron temperature, electron density, vibrational temperature, and gas temperature compared to the filamentary mode.

Differential diagnosis of gastric submucosal masses and external pressure lesions

Lesions of the left triangular ligament of the liver are rare,and there are even fewer cases of vascular tumors misdiagnosed as gastrointestinal stromal tumors.We comment on the two cases reported in the article.The article did not include pictures of laparoscopic surgery,making it unconvincing.For gastric submucosal lesions,enhanced computed tomography venous phase imaging may be beneficial for differential diagnosis.Although endoscopic ultrasound is an effective tool for diagnosing submucosal lesions of the stomach,due to various factors,it cannot achieve an accurate diagnosis.During endoscopic examination,a more accurate diagnosis can be made depending on the personal experience of the operators.

Advances in translational therapy for locally advanced gastric cancer

Translational therapy refers to a combination of chemotherapy,radiotherapy,targeted therapy,and immunotherapy for patients with advanced gastric cancer who are initially unable to undergo R0 resection.This treatment can achieve partial or complete remission of the unresectable tumors to meet the criteria for R0 resection,thus enabling the patients to prolong their survival time and improve their quality of life.In gastric cancer,translational therapy has been tried and improved.At present,there are a large number of patients with locally advanced gastric cancer in China,and the selection of suitable patients for transla-tional therapy to prolong objective survival and improve survival quality is one of the hot spots in the field of gastric cancer research.

CXCR4/SDF-1 axis is involved in lymph node metastasis of gastric carcinoma

AIM:To investigate the role of CXC chemokine receptor-4 (CXCR4) and stromal cell-derived factor-1 (SDF-1) in lymph node metastasis of gastric carcinoma.METHODS:In 40 cases of gastric cancer,expression of CXCR4 mRNA in cancer and normal mucous membrane and SDF-1 mRNA in lymph nodes around the stomach was detected using quantitative polymerase chain reaction (PCR) (TaqMan) and immunohistochemistric assay.SGC-7901 and MGC80-3 cancer cells were used to investigate the effect of SDF-1 on cell proliferation and migration.RESULTS:Quantitative reverse transcription PCR and immunohistochemistry revealed that the expression level of CXCR4 in gastric cancer was significantly higher than that in normal mucous membrane (1.6244 ± 1.3801 vs 1.0715 ± 0.5243,P < 0.05).The expression level of CXCR4 mRNA in gastric cancer with lymph node metastasis was also significantly higher than that without lymph node metastasis (0.823 ± 0.551 vs 0.392 ± 0.338,P < 0.05).CXCR4 expression was significantly related to poorly differentiated,high tumor stage and lymph node metastasis.Significant differences in the expression level of SDF-1 mRNA were found between lymph nodes in metastatic gastric cancer and normal nodes (0.5432 ± 0.4907 vs 0.2640 ± 0.2601,P < 0.05).The positive expression of SDF-1 mRNA in lymph nodes of metastatic gastric cancer was consistent with the positive expression of CXCR4 mRNA in gastric cancer (r=0.776,P < 0.01).Additionally,human gastric cancer cell lines expressed CXCR4 and showed vigorous proliferation and migratory responses to SDF-1.AMD3100 (a specific CXCR4 antagonist) was also found to effectively reduce the migration of gastric cancer cells.CONCLUSION:The CXCR4/SDF-1 axis is involved in the lymph node metastasis of gastric cancer.CXCR4 is considered as a potential therapeutic target in the treatment of gastric cancer.

Drug-induced liver injury in hospitalized patients with notably elevated alanine aminotransferase

AIM： To identify the proportion, causes and the nature of drug-induced liver injury （DILI） in patients with no- tably elevated alanine aminotransferase （ALT）. METHODS： All the inpatients with ALT levels above 10 times upper limit of normal range （ULN） were ret- rospectively identified from a computerized clinical laboratory database at our hospital covering a 12-mo period. Relevant clinical information was obtained from medical records. Alternative causes of ALT eleva- tions were examined for each patient, including bili- ary abnormality, viral hepatitis, hemodynamic injury, malignancy, DILI or undetermined and other causes. All suspected DILI cases were causality assessed usingthe Council for International Organizations of Medical Sciences scale, and only the cases classified as highly probable, probable, or possible were diagnosed as DILI. Comments related to the diagnosis of DILI in the medical record and in the discharge letter for each case were also examined to evaluate DILI detection by the treating doctors. RESULTS： A total of 129 cases with ALT 〉 i0 ULN were identified. Hemodynamic injury （n = 46, 35.7%）, DILl （n = 25, 19.4%） and malignancy （n = 21, 16.3%） were the top three causes of liver injury. Peak ALT val- ues were lower in DILI patients than in patients with hemodynamic injury （14.5 5.6 ULN vs 32.5 ：I： 30.7 ULN, P = 0.001）. Among DILI patients, one （4%） case was classified as definite, 19 （76%） cases were clas- sified as probable and 5 （20%） as possible according to the ClOMS scale. A hepatocellular pattern was ob- served in 23 （92%） cases and mixed in 2 （8%）. The extent of severity of liver injury was mild in 21 （84%） patients and moderate in 4 （16%）. Before discharge, 10 （40%） patients were recovered and the other 15 （60%） were improved. The improved patients tended to have a higher peak ALT （808 ＋ 348 U/L vs 623 ＋ 118 U/L, P = 0.016） and shorter treatment duration before discharge （8 ＋ 6 d vs 28 ~ 12 d, P = 0.008） compared with the recovered patients. Twenty-two drugs and 6 herbs were found associated with DILl. Antibacterials were the most common agents causing DILI in 8 （32%） cases, followed by glucocorticoids in 6 （24%） cases. Twenty-four （96%） cases received treatment of DILl with at least one adjunctive drug. Agents for treatment of DILI included anti-inflammatory drugs （e.g., glycyr- rhizinate）, antioxidants （e.g., glutathione, ademetionine 1,4-butanedisulfonate and tiopronin）, polyene phospha- tidyl choline and herbal extracts （e.g., protoporphyrin disodium and silymarin）. Diagnosis of DILl was not mentioned in the discharge letter in 60% of the cases. Relative to prevalent cases and cases from wards of internal medicine, incident cases and cases from surgi- cal wards had a higher risk of missed diagnosis in dis- charge letter [odds ratio （OR） 32.7, 95%CI （2.8-374.1）,CONCLUSION： DILI is mostly caused by use of anti- bacterials and glucocorticoids, and constitutes about one fifth of hospitalized patients with ALT 〉 10 ULN. DILI is underdiagnosed frequently.

Correlation of Skp2 overexpression to prognosis of patients with nasopharyngeal carcinoma from South China

S-phase kinase-associated protein 2 (Skp2), which plays a role in cell cycle regulation, is commonly overexpressed in a variety of human cancers and associated with poor prognosis. However, its role in nasopharyngeal carcinoma (NPC) is not well understood. In this study, we examined the clinical significance of Skp2, with a particular emphasis on overall survival (OS) and disease-free survival (DFS), in NPC cases in South China, where NPC is an epidemic. Additionally, we explored the function of Skp2 in maintaining a cancer stem cell -like phenotype in NPC cell lines. Skp2 expression was assessed for 127 NPC patients using tissue microarrays and immunohistochemistry and analyzed together with clinicopathologic features, OS, and DFS. Skp2 expression was detectable, or positive, in 75.6% of patients. Although there was no correlation between Skp2 and any clinicopathologic factor, Skp2 expression significantly portended inferior OS (P = 0.013) and DFS (P = 0.012). In the multivariate model, Skp2 expression remained significantly predictive of poor OS [P = 0.009, risk ratio (RR) = 4.06] and DFS (P = 0.008, RR = 3.56), and this was also true for clinical stage (P = 0.012 and RR=3.201 for OS; P = 0.002 and RR=1.94 for DFS) and sex (P = 0.016 and RR=0.31 for OS; P = 0.006 and RR = 0.27 for DFS). After Skp2 knockdown, a colony formation assay was used to evaluate the self-renewal property of stem-like cells in the NPC cell lines CNE-1 and CNE-2. The colony formation efficiency in CNE-1 and CNE-2 cells was decreased. In Skp2-transfected CNE-1 and CNE-2 cells, side population (SP) proportion was increased as detected by flow cytometry. Skp2 is an independent prognostic marker for OS and DFS in NPC. Skp2 may play a role in maintaining the cancer stem cell-like phenotype of NPC cell lines.

Clinical application of self-expanding metallic stent in the management of acute left-sided colorectal malignant obstruction

AIM： To summarize our experience with the application of self-expanding metallic stent （SEMS） in the management of acute left-sided colorectal malignant obstruction. METHODS： A retrospective chart review of all patients undergoing placement of SENS between April 2000 and January 2004 was performed. RESULTS： Insertion of SENS was attempted in 26 patients under fluoroscopic guidance with occasional endoscopic assistance. The sites of lesions were located in splenic flexure of two patients, left colon of seven patients, sigmoid colon of eight patients and rectum of nine patients. The intended uses of SENS were for palliation in 7 patients and as a bridge to elective surgery in 19 patients. In the latter group, placement of SENS allowed for preoperative systemic and bowel preparation and the following one-stage anastomosis. Successful stent placement was achieved in 22 （85%） of the 26 patients. The clinical bowel obstruction resolved 24 hours after successful stent placement in 21 （95%） patients. Three SENS-related minor complications occurred, two stents migrated and one caused anal pain. CONCLUSION： SEMS represents an effective and safe tool in the management of acute malignant colorectal obstruction. As a bridge to surgery, SEMS can provide time for systematic support and bowel preparation and obviate the need for fecal diversion or on-table lavage. As a palliative measure, SEMS can eliminate the need for emergent colostomy.

Association of atherosclerotic plaque features with collateral circulation status in elderly patients with chronic carotid stenosis

Objective To determine the association of carotid plaque features with collateral circulation status in elderly patients with moderate to severe carotid stenosis.Methods Elderly patients(>60 years)with moderate to severe carotid stenosis were recruited and categorized into good and poor collateral circulation groups,and underwent magnetic resonance imaging and computed tomography imaging.The carotid plaque features including lipid-rich necrotic core,intraplaque hemorrhage,calcification,and fibrous cap rupture(FCR)were evaluated,and maximum wall thickness,normalized wall index(NWI),and luminal stenosis were measured.The association between these variables and collateral circulation status was analyzed.Results Of the 97 patients(78 males,mean age:69.0±6.1 years),19(19.6%)had poor collaterals.The poor collateral group had a significantly higher NWI(93.7%±5.0%vs.89.0%±7.9%,P=0.011),a greater extent of stenosis(80.0%±11.4%vs.75.3%±9.4%,P=0.036)and FCR(84.2%vs.55.1%,P=0.020)compared with good collateral group.Carotid NWI(OR=3.83,95%CI:1.36–10.82,P=0.011)and more FCR(OR=6.77,95%CI:1.35–33.85,P=0.020)were associated with poor collateral circulation after adjustment for the confounding factors.The combination of NWI,FCR,systolic blood pressure,and triglycerides had the highest area-under-the-curve(AUC=0.85)for detection of poor collaterals.Conclusions Carotid plaque features,specifically NWI and FCR,are independently associated with poor collateral circulation,and the combination of carotid plaque features and traditional risk factors has a stronger predictive value for poor collateral circulation than plaque features alone.

Recent advances in Fe-N-C-and Co-N-C-based materials as bifunctional electrocatalysts for oxygen reduction and oxygen evolution

Fe-nitrogen-carbon(Fe-N-C)-and Co-nitrogen-carbon(Co-N-C)-based electrocatalysts have been widely concerned because of their high OER/ORR activity,low metal cost,and simple preparation.The exploration of Fe-N-C and Co-N-C single atombased catalysts with high activity and stability to overcome the slow kinetics of oxygen reduction and oxygen evolution reactions is also the key to the development of efficient electrolytic water,fuel cells,and rechargeable metal-air batteries.Fe-N-C and Co-N-C single atom-based electrocatalysts have the advantages of a high utilization rate of metal atoms and high electrocatalytic activity,and are ideal catalysts for promoting electrochemical energy conversion and storage.The general principles of designing Fe-N-C and Co-N-C single atom-based electrocatalysts are reviewed in this paper.Then,the strategies to improve the bifunctional catalytic activity and stability are proposed.Finally,the challenges and prospects of Fe-N-C and Co-N-C single atom-based catalysts are well summarized.This review will provide a reference for the directed optimization of Fe-N-C and Co-N-C single atom-based catalysts.

用于锌-空气电池空气电极的无贵金属掺杂碳基电催化剂

低成本、高能量密度、安全的锌空气电池(ZABs)被认为是最有潜力的绿色储能设备之一.然而,ZABs的性能受到多种组分性能的影响,包括锌阳极的钝化和腐蚀,电解质的碱性,特别是空气阴极上缓慢的O_(2)氧化还原反应.其中,阴极电催化剂对ZABs的性能起着至关重要的作用.氮掺杂碳基材料作为电催化剂具有价格低、稳定性好、结构可控、导电性高等优点,可有效提高ZABs的整体性能.到目前为止,该领域已经发表了大量论文,但关于ZABs用氮掺杂碳基材料的最新进展还没有系统的综述.本文对这一迅速发展的重要领域进行了及时、全面的总结.本文首先介绍了ZABs的重要组成部分和工作原理,并简要介绍了ZABs的阳极和电解液的研究进展.然后,提出了目前先进的氮掺杂碳基ZABs催化剂的优化策略,包括各种常用的氮掺杂碳催化剂的制备方法.除了不含金属的氮掺杂碳基催化剂外,还讨论了氮掺杂碳基催化剂与非贵金属偶联的研究进展.本文系统地综述了各种催化剂的性质、制备方法和详细催化机理,并对其优缺点进行了比较.本文不仅介绍了最新的研究进展,还为指导高性能氮掺杂碳基电催化剂的设计提供了基本思路,有助于其在ZABs中的大规模应用.

Mesh Erosion into Sigmoid Colon after Inguinal Hernia Repair

To the Editor： Tension-free henlia repair with mesh is currently the most popular technique for herniorrhaphy. Although it is well tolerated with few complications, late-onset complications, such as mesh migration, erosion into associated structures, enterocutaneous fistula, and abscess formation, have been reported We herein report a case of a 67-year-old male with mesh erosion into the sigmoid colon after inguinal hernia repair.