Electron transfer mechanisms, characteristics and applications of biological cathode microbial fuel cells – A mini review

AbstractSince the microbial fuel cells (MFCs) research in the laboratory has reached an unprecedented success, it has raised a research upsurge internationally in recent years. However, compared with laboratory studies, the widespread applications of the conventional MFCs were restrained by the limitations of high cost and low efficiency. This stimulates researchers to overcome the obstacles. In this condition, bio-cathodes attracted their great interests. This paper is a brief review about the experimental progress of bio-cathodes in microbial fuel cells with an emphasis on the classification according to the final electron acceptors and the comparison with the traditional abiotic cathode MFCs. Bio-cathodes are feasible in removing nutrient in wastewater treatment and being used as biosensors in bioremediation. Presently, tremendous efforts are being made in investigating appropriate electrodes and dominant strains to achieve the effective practical applications

Resistance to Grapevine leafroll associated virus-2 is conferred by post-transcriptional gene silencing in transgenic Nicotiana benthamiana

Grapevine leafroll-associated virus-2 (GLRaV-2) is an important component of the leafroll disease complex in grapevine. We have previously sequenced the GLRaV-2 genome and identified the coat protein (CP) gene. The objective of this study is to test the concept of pathogen-derived resistance against a closterovirus associated with grapevine leafroll disease. Because GLRaV-2 is capable of infecting Nicotiana benthamiana, we decided to test the concept on this herbaceous host. Thirty-seven T0 transgenic N.benthamiana plants expressing the GLRaV-2 CP gene were regenerated following Agrobacterium-mediated transformation. Disease resistance was evaluated in greenhouse-grown T1 and T2 plants by mechanical inoculation with GLRaV-2. Although all the inoculated non-transgenic plants showed symptoms 2-4weeks post inoculation, various numbers of transgenic plants (16-100%) in 14 of 20 T1 lines tested were not infected. In these resistant plants, GLRaV-2 was not detectable by enzyme linked immunosorbent assay. Although virus resistance was confirmed in T2 progenies, the percentage of resistant plants was generally lower (0-63%) than that of the corresponding T1 lines (0-100%). Northern blot and nuclear run-off results showed that virus resistance in the transgenic plants was consistently associated with the low level of transgene RNA transcript suggesting a post-transcriptional gene silencing. The success of pathogen-derived resistance to GLRaV-2 in transgenic N.benthamiana plants represents the first step towards eventual control of the leafroll disease in grapevines using this strateg

Hall effect and magnetoresistance in single crystals of NdFeAsO1−x_{1-x}Fx_{x}

Hall effect and magnetoresistance have been measured on single crystals of $NdFeAsO_{1-x}F_{x}$ with x = 0 ($T_c$ = 0 $$K) and x = 0.18 ($T_c$ = 50 $$K). For the undoped samples, strong Hall effect and magnetoresistance with strong temperature dependence were found below about 150 K. The magnetoresistance was found to be as large as 30% at 15 K at a magnetic field of 9 T. From the transport data we found that the transition near 155 K was accomplished in two steps: first one occurs at 155 K which may be associated with the structural transition, the second one takes place at about 140 K which may correspond to the spin-density wave like transition. In the superconducting sample with $T_c$ = 50 $$K, it is found that the Hall coefficient also reveals a strong temperature dependence with a negative sign. But the magnetoresistance becomes very weak and does not satisfy the Kohler's scaling law. These dilemmatic results (strong Hall effect and very weak magnetoresistance) prevent to understand the normal state electric conduction by a simple multi-band model by taking account the electron and hole pockets. Detailed analysis further indicates that the strong temperature dependence of $R_H$ cannot be easily understood with the simple multi-band model either. A picture concerning a suppression to the density of states at the Fermi energy in lowering temperature is more reasonable. A comparison between the Hall coefficient of the undoped sample and the superconducting sample suggests that the doping may remove the nesting condition for the formation of the SDW order, since both samples have very similar temperature dependence above 175 K.Comment: 8 pages, 9 figure

Covert Laparoscopic Cholecystectomy: A New Minimally Invasive Technique

To further improve our developed transumbilical endoscopic surgery (TUES), we developed a completely covert laparoscopic cholecystectomy (LC). Twelve cases of LC were recruited for this new approach. First, a 10-mm trocar was placed above the umbilicus for inserting the laparoscope. Two 5-mm trocars were then placed near the right and left ends of the superior margin of the suprapubic hair. After the 5-mm 30° laparoscope was shifted to the left suprapubic trocar, the harmonic scalper, electric hook, and grasper were inserted either through the 10-mm umbilical trocar or through the right suprapubic trocar. All gallbladders were successfully removed without intraoperative complications. The mean operating time was 28.5±5.7min (range 20-45min). All patients felt well after surgery and did not need postoperative analgesia. They resumed free oral intake 6h after the procedure. All patients were satisfied with the appearance of the incisions, which were completely hidden in the umbilicus and suprapubic hair. The approach we developed has overcome both external instrument interference around the umbilicus and the loss of triangulation in the operative field. It is relatively simpler than a typical TUES and offers better cosmetic results

A comprehensive review on the ferroelectric orthochromates: Synthesis, property, and application

Multiferroics represent a class of advanced materials for promising applications and stand at the forefront of modern science for the special feature possessing both charge polar and magnetic order. Previous studies indicate that the family of RECrO3 (RE = rare earth) compounds is likely another rare candidate system holding both ferroelectricity and magnetism. However, many issues remain unsolved, casting hot disputes about whether RECrO3 is multiferroic or not. For example, an incompatibility exists between reported structural models and observed ferroelectric behaviors, and it is not easy to determine the spin canting degree. To address these questions, one key step is to grow single crystals because they can provide more reliable information than other forms of matter do. In this review, the parent and doped ferroelectric YCrO3 compounds are comprehensively reviewed based on scientific and patent literatures from 1954 to 2022. The materials syntheses with different methods, including poly-, nano-, and single-crystalline samples and thin films, are summarized. The structural, magnetic, ferroelectric and dielectric, optical, and chemical-pressure (on Y and Cr sites by doping) dependent chemical and physical properties and the corresponding phase diagrams, are discussed. Diverse (potential) applications, including anti-corrosion, magnetohydrodynamic electrode, catalyst, negative-temperature-coefficient thermistor, magnetic refrigeration, protective coating, and solid oxide fuel cell, are present. To conclude, we summarize general results, reached consensuses, and existing controversies of the past nearly 69 years of intensive studies and highlight future research opportunities and emerging challenges to address existing issues.Comment: 69 pages, 35 figures, accepted by Coordination Chemistry Review

Tumor feeding artery reconstruction with multislice spiral CT in the diagnosis of pelvic tumors of unknown origin.

PURPOSEWe aimed to compare multislice spiral computed tomography (MSCT) angiography diagnosis with both surgical findings and postoperative pathological results in patients with pelvic tumors of unknown origin. In addition, the diagnostic accuracy of MSCT angiography was compared with that of routine computed tomography for tumor feeding artery volume reconstruction to determine the origin and nature of pelvic tumors. MATERIALS AND METHODSThe records of 43 patients with pelvic tumors of unknown origin who underwent MSCT angiography were retrospectively reviewed. Volume reconstructions using add vessel and merge views methods were performed for abdominal and pelvic blood vessels. The tumor origin was identified based on observations of the origin, number, morphology, starting/ending locations, route, and distribution of the tumor feeding arteries. RESULTSOverall, the mean tumor diameter was 9.8±3.5 cm (range, 4.2–23.5 cm); 11 tumors (25.6%) were cystic in nature; and 32 tumors (74.4%) were either solid/cystic or solid in nature. When considering all MSCT angiography examinations used to predict the nature of the tumor (e.g., malignant or benign), the sensitivity and specificity were 77.3% and 95.2%, respectively. The positive and negative predictive values were 94.4% and 80%, respectively. The overall diagnostic accuracy was 86.05% with an area under the curve of 0.961 (95% confidence interval, 0.913–1.000). CONCLUSIONSMSCT angiography volume reconstruction for pelvic tumor feeding arteries of unknown origin is highly valuable for localization, qualitative diagnosis, and quantitative diagnosis of pelvic tumors

Superconductivity at 22.3 K in SrFe2-xIrxAs2

By substituting the Fe with the 5d-transition metal Ir in SrFe2As2, we have successfully synthesized the superconductor SrFe2-xIrxAs2 with Tc = 22.3 K at x = 0.5. X-ray diffraction indicates that the material has formed the ThCr2Si2-type structure with a space group I4/mmm. The temperature dependence of resistivity and dc magnetization both reveal sharp superconducting transitions at around 22 K. An estimate on the diamagnetization signal reveals a high Meissner shielding volume. Interestingly, the normal state resistivity exhibits a roughly linear behavior up to 300 K. The superconducting transitions at different magnetic fields were also measured yielding a slope of -dHc2/dT = 3.8 T/K near Tc. Using the Werthamer-Helfand-Hohenberg (WHH) formula, the upper critical field at zero K is found to be about 58 T. Counting the possible number of electrons doped into the system in SrFe2-xIrxAs2, we argue that the superconductivity in the Ir-doped system is different from the Co-doped case, which should add more ingredients to the underlying physics of the iron pnictide superconductors.Comment: 4 pages, 4 figure