Current rectification by asymmetric molecules: An ab initio study

We study current rectification effect in an asymmetric molecule HOOC-C$_6$H$_4$-(CH$_2$)$_n$ sandwiched between two Aluminum electrodes using an {\sl ab initio} nonequilibrium Green function method. The conductance of the system decreases exponentially with the increasing number $n$ of CH$_2$. The phenomenon of current rectification is observed such that a very small current appears at negative bias and a sharp negative differential resistance at a critical positive bias when $n\ge 2$. The rectification effect arises from the asymmetric structure of the molecule and the molecule-electrode couplings. A significant rectification ratio of $\sim$38 can be achieved when $n=5$.Comment: to appear in J. Chem. Phy

Investigating the A-level Chinese examination in England:teachers’ perspectives

This paper investigates England’s A-level Chinese examination from teachers’ perspectives. This examination is one of the subject-based qualifications typically taken by students at the age of 18 who plan to go to university. Despite the government’s promotion of Chinese teaching in different educational settings, there remains a lack of empirical research in this area, especially focusing on this examination. This paper, which is part of a larger project that explores the validity of A-level Chinese from various perspectives, reports findings from surveys and interviews with Chinese-language teachers in England, both native and non-native speakers. The primary aim is to understand teachers’ attitudes toward various aspects of the A-level Chinese examination, including difficulties in the listening and reading papers, textbook suitability, and continuity from GCSE studies. Potential obstacles to the promotion of A-level Chinese teaching and learning are also identified in this paper

Enhancing the hydrolysis of excess sludge using thermophilic Bacillus sp. Hnu under different oxygen supply conditions

A thermophilic Bacillus strain was isolated from excess sludge in the present study. The 16S rDNA analysis indicated that this strain was a Bacillus sp. and has not been reported previously (named Bacillus sp. Hnu). The aim of this paper was to investigate the enhanced efficiency of excess sludge hydrolysis by the addition of thermophilic Bacillus sp. Hnu under different oxygen supply conditions. The results indicated that higher temperature and more oxygen supply was advantageous to the volatile suspended solid removal ratio with the same effect to that of protease activity. The maximum volatile suspended solid removal ratio was achieved at 21.5 %, 42.5 %, and 54.4 % after 108 h digestion at pH 6.9 and 60°C and increased by 17.2 %, 38 %, and 45.4 % under anaerobic, microaerobic, and aerobic conditions compared with the control test, respectively. The hydrolysis rate constants for the anaerobic, microaerobic, and aerobic conditions were 3, 4.8, and 7 times (40°C) and 3.5, 9.8, and 11.8 times (50°C) and 2.7, 7.2, and 10.3 times (60°C). Hydrolysis performance indicated that the Bacillus sp. Hnu could accelerate the hydrolysis rate. The kinetic study showed that the hydrolysis of sludge with Bacillus sp. Hnu and the control test followed the first-order kinetics except at 60°C

Taphonomic analysis of the exceptional preservation of early bird feathers during the early Cretaceous period in Northeast China

Fossil soft tissues contain important and irreplaceable information on life evolution, and on the comprehensive understanding of the nature of Mesozoic ecosystems. Compared to other fossil soft tissues, Jehol Biota feathers are more commonly reported. However, taphonomic analysis of these feathers is lacking. Here, five Jehol Biota specimens of early bird Sapeornis chaoyangensis with differently preserved feathers were selected. One specimen, STM 15-36, has a complete set of extraordinarily preserved feathers. An interesting consequence was revealed by their host sediment Zr/Rb analysis that specimen STM 15-36 possesses the coarsest sediment grain size but the best-preserved feathers. More geochemical analyses of host sediments, including organic carbon isotopes and major elements, were conducted to restore the paleoenvironment during those Sapeornis’ burial. The result mainly shows that the paleoclimate when Sapeornis STM 15-36 was buried is warmer and wetter than those of the other four; STM 15-36 host sediment has a pure terrestrial-derived organic input, while the others are aquatic algae. In addition, redox-sensitive trace elements analysis indicates the lake bottom-water preserved Sapeornis STM 15-36 is anoxic and restricted, being more oxygen-depleted than those of the other four. Therefore, the transportation and burial of Sapeornis STM 15-36 were preliminarily inferred as: the carcass of Sapeornis STM 15-36 was transported rapidly into the lake by a short and strong rain flush, and then was buried quickly by the accompanying terrestrial debris; the subsequent anoxic and restricted burial environment inhibited bioturbation and hydrodynamic disturbance on Sapeornis STM 15-36 and its host sediments, allowing its whole set of feathers to be delicately preserved. This finding provides a valuable case study on understanding the taphonomy of fossil soft tissues’ exceptional preservation in Jehol Biota

DualTable: A Hybrid Storage Model for Update Optimization in Hive

Hive is the most mature and prevalent data warehouse tool providing SQL-like interface in the Hadoop ecosystem. It is successfully used in many Internet companies and shows its value for big data processing in traditional industries. However, enterprise big data processing systems as in Smart Grid applications usually require complicated business logics and involve many data manipulation operations like updates and deletes. Hive cannot offer sufficient support for these while preserving high query performance. Hive using the Hadoop Distributed File System (HDFS) for storage cannot implement data manipulation efficiently and Hive on HBase suffers from poor query performance even though it can support faster data manipulation.There is a project based on Hive issue Hive-5317 to support update operations, but it has not been finished in Hive's latest version. Since this ACID compliant extension adopts same data storage format on HDFS, the update performance problem is not solved. In this paper, we propose a hybrid storage model called DualTable, which combines the efficient streaming reads of HDFS and the random write capability of HBase. Hive on DualTable provides better data manipulation support and preserves query performance at the same time. Experiments on a TPC-H data set and on a real smart grid data set show that Hive on DualTable is up to 10 times faster than Hive when executing update and delete operations.Comment: accepted by industry session of ICDE201

Ovarian cancer initially presenting with isolated ipsilateral superficial inguinal lymph node metastasis: a case study and review of the literature

Isolated superficial inguinal metastases without any extended intra-abdominal spread is a rare event in patients with ovarian carcinoma. Here we report an isolated superficial inguinal metastasis in a patient with primary ovarian cancer. A 54-year-old Chinese patient with primary ovarian cancer, had an isolated painless enlarged right groin swelling (3×2cm) as the only manifestation, preoperative pathology confirmed metastatic adenocarcinoma. Gynecologic examination, transvaginal ultrasonography of the abdominopelvic cavity revealed a 5-cm mixed, right adnexal mass. At exploratory laparotomy, there was little intra-abdominal tumor dissemination but 100 ml of faint yellow peritoneal fluid and a 5-cm right ovarian tumor with intact capsule. Staging operation was performed and postoperative pathology confirmed adenocarcinoma located within right ovarian, with no evidence of involvement of other sites. Then the patient received adjuvant chemotherapy for Stage IVB. Five years later, the patient is currently still alive without evidence of recurrent disease. This case indicate that ovarian carcinoma isn’t a disease localized only within the intra-peritoneal cavity, isolated superficial inguinal lymph node metastasis might occur in rare cases via potential lymphatic and (or) hematogenous route under special conditions. We propose the need to investigate the possible mechanisms, risk factors, metastatic patterns, the biology and natural history of such patients in a large-scale and multicenter analysis. Furthermore, efforts should be made for earlier and differential diagnosis and finally prolong survival time for such patients

The role of technetium-99m methoxyisobutyl isonitrile scintigraphy in predicting the therapeutic effect of chemotherapy against nasopharyngeal carcinoma

BACKGROUND: The authors prospectively evaluated the correlation between technetium-99m methoxyisobutyl isonitrile ( 99m Tc-MIBI) accumulation in tumors and response to induction chemotherapy in patients with nasopharyngeal carcinoma (NPC). METHODS: Eighty-six patients with locally advanced NPC underwent single-photon emission computed tomography 15 minutes after an intravenous injection of 740 megabecquerels (20 mCi) 99m Tc-MIBI before chemotherapy. The tumor uptake ratio (TUR) was calculated. Two weeks after the second cycle of combined chemotherapy with 5-fluorouracil (5-FU) and cisplatin (DDP), the tumor response rate was evaluated. The correlation between 99m Tc-MIBI accumulation in tumors and response to chemotherapy with 5-FU/DDP was examined. RESULTS: Positive accumulation of 99m Tc-MIBI in tumors was observed in 76 patients (88.4%). The tumor response was a complete response (CR) in 8 patients, a partial response (PR) in 68 patients, stable disease (SD) in 9 patients, and progressive disease (PD) in 1 patient. The response rate (CR and PR) to 5-FU/DDP chemotherapy in patients who had positive 99m Tc-MIBI accumulation (tumor uptake ratio [TUR] >1.1) was higher than that in patients who had negative 99m Tc-MIBI accumulation (TUR ≤1.1; 98.7% vs 10%; P < .001). CONCLUSIONS: Patients with negative 99m Tc-MIBI accumulation were resistant to 5-FU/DDP chemotherapy. 99m Tc-MIBI imaging in patients with NPC was capable of predicting tumor response to chemotherapy with 5-FU/DDP and can help in the selection of patients for induction chemotherapy. Cancer 2011. © 2010 American Cancer Society.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/84384/1/25802_ftp.pd

Effects of relative orientation of the molecules on electron transport in molecular devices

Effects of relative orientation of the molecules on electron transport in molecular devices are studied by non-equilibrium Green's function method based on density functional theory. In particular, two molecular devices, with the planer Au$_{7}$ and Ag$_{3}$ clusters sandwiched between the Al(100) electrodes are studied. In each device, two typical configurations with the clusters parallel and vertical to the electrodes are considered. It is found that the relative orientation affects the transport properties of these two devices completely differently. In the Al(100)-Au$_7$-Al(100) device, the conductance and the current of the parallel configuration are much larger than those in the vertical configuration, while in the Al(100)-Ag$_{3}$-Al(100) device, an opposite conclusion is obtained