AIM: To determine the efficacy of our therapeutic strategy for Helicobacter pylori (H. pylori) eradication and to identify predictive factors for successful eradication. METHODS: From April 2006 to June 2010, we retro...AIM: To determine the efficacy of our therapeutic strategy for Helicobacter pylori (H. pylori) eradication and to identify predictive factors for successful eradication. METHODS: From April 2006 to June 2010, we retrospectively assessed 2428 consecutive patients (1025 men, 1403 women; mean age 55 years, age range 18-92 years) with gastric histology positive for H. pylori infection referred to our unit for 13-C urea breath test(UBT), after first-line therapy with proton pump inhibitor (PPI) b.i.d. + amoxicillin 1 g b.i.d. + clarithromycin 500 mg b.i.d. for 7 d. Patients who were still positive to UBT were recommended a second-line therapy (PPI b.i.d. + amoxicillin 1 g b.i.d. + tinidazole 500 mg b.i.d. for 14 d). Third choice treatment was empirical with PPI b.i.d. + amoxicillin 1 g b.i.d. + levofloxacin 250 mg b.i.d. for 14 d. RESULTS: Out of 614 patients, still H. pylori-positive after first-line therapy, only 326 and 19 patients respectively rechecked their H. pylori status by UBT after the suggested second and third-line regimens. "Per protocol" eradication rates for first, second and thirdline therapy were 74.7% (95% CI: 72.7%-76.4%), 85.3% (95% CI: 81.1%-89.1%) and 89.5% (95% CI: 74.9%-103%) respectively. The overall percentage of patients with H. pylori eradicated after two treatments was 97.8% (95% CI: 97.1%-98.4%), vs 99.9% (95% CI: 99.8%-100%) after three treatments. The study found that eradication therapy was most effective in patients with ulcer disease (P < 0.05, P = 0.028), especially in those with duodenal ulcer. Smoking habits did not significantly affect the eradication rate. CONCLUSION: First-line therapy with amoxicillin and clarithromycin produces an H. pylori eradication rate comparable or superior to other studies and secondline treatment can still be triple therapy with amoxicillin and tinidazole.展开更多
The electronic transport properties of oligoacenes sandwiched between two Au（111） surfaces with serial and parrallel configurations were investigeted by using a fully self-consistent nonequilibrium Green＇s function...The electronic transport properties of oligoacenes sandwiched between two Au（111） surfaces with serial and parrallel configurations were investigeted by using a fully self-consistent nonequilibrium Green＇s function method combined with density functional calculations. This theoretical results show that the conductivity of oligoacenes with both sandwiched configurations at low bias voltage is mainly determined by the tail of the transmission peak from the perturbed highest occupied molecular orbital. When the molecular length increases, the zero-bias voltage conductance G（0） of oligoacenes with serial configuration neither follows Magoga＇s exponential law nor displays the even-odd oscillation effect, while the G（O） of the oligoacenes sandwiched with parallel configuration monotonically increases. The reduction of energy gaps, the alignment of the Fermi level, and the spatial distribution of the perturbed molecular orbitals are used to self-consistently explore the transport mechanism through oligoacenes.展开更多
We have investigated the electron transport properties of a N24B24 molecule coupled to two metallic contacts with a combination of GW approximation and the non-equilibrium Green＇s- function technique. The calculation...We have investigated the electron transport properties of a N24B24 molecule coupled to two metallic contacts with a combination of GW approximation and the non-equilibrium Green＇s- function technique. The calculations indicate that the four and three resonant tunneling peaks are seen for the density of states （DOS） curves in the cases of single and multiple atomic contacts, respectively. The off state and negative differential resistance （NDR） effect are observed in the I-V characteristics of the N24B24 molecule. The NDR behavior is also observed in voltages of about 354.5, 354, 354.6, and 354.3 V for one, four, six, and eight atomic contacts. Also, the I-V characteristics of N24B24 are in off state at low voltages that is independent of the contact types. The current contact types and indicate that N24B24 molecule curves against the gate voltage depend on behaves as a semiconductor.展开更多
Motivated by the recent advances of transition-metal-nitrogen-carbon (TM-N-C) materials in catalysis, we investigate the electronic structure and transport properties of FeN3-embedded armchair and zigzag graphene nano...Motivated by the recent advances of transition-metal-nitrogen-carbon (TM-N-C) materials in catalysis, we investigate the electronic structure and transport properties of FeN3-embedded armchair and zigzag graphene nanoribbons (FeN3@AGNRs, FeN3@ZGNRs) with different widths. The first-principles results indicate that the FeN3 induces significant changes on the band structures of both ZGNRs and AGNRs, making the resultant systems quite different from the pristine ones and own room-temperature stable ferromagnetic (FM) ground states. While only FeN3@AGNRs possess a significant spin-dependent negative differential resistance (NDR) and a striking current polarization (nearly 100%) behaviors, due to that FeN3 introduces two isolated spin-down states, which contribute current with different performances when they couple with different frontier orbits. It is suggested that by embedding FeN3 complexes, AGNRs can be used to build spin devices in spintronics.展开更多
We investigate the electronic transport properties of atomic carbon chain-graphene junctions by using the density-functionla theory combining with the non-equilibrium Green＇s functions. The results show that the tran...We investigate the electronic transport properties of atomic carbon chain-graphene junctions by using the density-functionla theory combining with the non-equilibrium Green＇s functions. The results show that the transport properties are sensitively dependent on the contact geometry of carbon chain. From the calculated I-V curve we find negative differential resistance （NDR） in the two types of junctions. The NDR can be considered as a result of molecular orbitals moving related to the bias window.展开更多
The effect of terminal groups on the electron transport through metal-molecule-metal system has been investigated using nonequilibrium Green's function (NEGF) formalism combined with extended Huckel theory (EHT). ...The effect of terminal groups on the electron transport through metal-molecule-metal system has been investigated using nonequilibrium Green's function (NEGF) formalism combined with extended Huckel theory (EHT). Au-molecule-Au junctions are constructed with borazine and BCN unit structure as core molecule and sulphur (S), oxygen (O), selenium (Se) and cyano-group (CN) as terminal groups. The electron transport characteristics of the borazine and BCN molecular systems are analyzed through the transmission spectra and the current-voltage curve. The results demonstrate that the terminal groups modifying the transport behaviors of these systems in a controlled way. Our result shows that, selenium is the best linker to couple borazine to Au electrode and oxygen is the best one to couple BCN to Au electrode. Furthermore, the results of borazine systems are compared with that of BCN molecular systems and are discussed. Simulation results show that the conductance through BCN molecular systems is four times larger than the borazine molecular systems. Negative differential resistance behavior is observed with borazine-CN system and the saturation feature appears in BCN systems.展开更多
Organic spintronics refers to control spin dependent transport through organic materials.In the last two decades,extraordinary development has been achieved for organic-spintronics.A series of theoretical and experime...Organic spintronics refers to control spin dependent transport through organic materials.In the last two decades,extraordinary development has been achieved for organic-spintronics.A series of theoretical and experimental studies have been done to reveal the mechanisms of spin dependent transport properties.The theoretical analysis is based on the non-equilibrium Green's function formalism provides a mathematical framework for solving the transmission coefficients in the Landauer formula from atomistic first principles without any phenomenological parameters.In this article,we provide a brief theoretical review on organic spintronics devices and device physics therein.展开更多
We study the electron transport through a special quantum-dot(QD)structure composed of three QDs and two Majorana bound states(MBSs)using the nonequilibrium Green’s function technique.This QD-MBS ring structure inclu...We study the electron transport through a special quantum-dot(QD)structure composed of three QDs and two Majorana bound states(MBSs)using the nonequilibrium Green’s function technique.This QD-MBS ring structure includes two channels with the two coupled MBSs being Channel 1 and one QD being Channel 2,and three types of transport processes such as the electron transmission(ET),the Andreev reflection(AR),and the crossed Andreev reflection(CAR).By comparing the ET,AR,and CAR processes through Channels 1 and 2,we make a systematic study on the transport properties of the QD-MBS ring.It is shown that there appear two kinds of characteristic transport patterns for Channels 1 and 2,as well as the interplay between the two patterns.Of particular interest is that there exists an AR-assisted ET process in Channel 2,which is different from that in Channel 1.Thus a clear"X"pattern due to the ET and AR processes appears in the ET,AR,and CAR transmission coefficients.Moreover,we study how Channel 2 affects the three transport processes when Channel 1 is tuned in the ET and CAR regimes.It is shown that the transport properties of the ET,AR and CAR processes can be adjusted by tuning the energy level of the QD embedded in Channel 2.We believe this research should be a helpful reference for understanding the transport properties in the QD-MBS coupled systems.展开更多
文摘AIM: To determine the efficacy of our therapeutic strategy for Helicobacter pylori (H. pylori) eradication and to identify predictive factors for successful eradication. METHODS: From April 2006 to June 2010, we retrospectively assessed 2428 consecutive patients (1025 men, 1403 women; mean age 55 years, age range 18-92 years) with gastric histology positive for H. pylori infection referred to our unit for 13-C urea breath test(UBT), after first-line therapy with proton pump inhibitor (PPI) b.i.d. + amoxicillin 1 g b.i.d. + clarithromycin 500 mg b.i.d. for 7 d. Patients who were still positive to UBT were recommended a second-line therapy (PPI b.i.d. + amoxicillin 1 g b.i.d. + tinidazole 500 mg b.i.d. for 14 d). Third choice treatment was empirical with PPI b.i.d. + amoxicillin 1 g b.i.d. + levofloxacin 250 mg b.i.d. for 14 d. RESULTS: Out of 614 patients, still H. pylori-positive after first-line therapy, only 326 and 19 patients respectively rechecked their H. pylori status by UBT after the suggested second and third-line regimens. "Per protocol" eradication rates for first, second and thirdline therapy were 74.7% (95% CI: 72.7%-76.4%), 85.3% (95% CI: 81.1%-89.1%) and 89.5% (95% CI: 74.9%-103%) respectively. The overall percentage of patients with H. pylori eradicated after two treatments was 97.8% (95% CI: 97.1%-98.4%), vs 99.9% (95% CI: 99.8%-100%) after three treatments. The study found that eradication therapy was most effective in patients with ulcer disease (P < 0.05, P = 0.028), especially in those with duodenal ulcer. Smoking habits did not significantly affect the eradication rate. CONCLUSION: First-line therapy with amoxicillin and clarithromycin produces an H. pylori eradication rate comparable or superior to other studies and secondline treatment can still be triple therapy with amoxicillin and tinidazole.
基金ACKNOWLEDGMENTS We thank Professor Wan-zhen Liang for helpful discussion. This work was completed in her group. This work was supported by the National Natural Science Foundation of China （No.20773112 and No.10674121）, the National Key Basic Research Program （No.2006CB922000）, the Science and Technological Fund of Anhui Province for Outstanding Youth （No.08040106833）, the USTC-HP HPC project, and the SCCAS and Shanghai Supercomputer Center.
文摘The electronic transport properties of oligoacenes sandwiched between two Au（111） surfaces with serial and parrallel configurations were investigeted by using a fully self-consistent nonequilibrium Green＇s function method combined with density functional calculations. This theoretical results show that the conductivity of oligoacenes with both sandwiched configurations at low bias voltage is mainly determined by the tail of the transmission peak from the perturbed highest occupied molecular orbital. When the molecular length increases, the zero-bias voltage conductance G（0） of oligoacenes with serial configuration neither follows Magoga＇s exponential law nor displays the even-odd oscillation effect, while the G（O） of the oligoacenes sandwiched with parallel configuration monotonically increases. The reduction of energy gaps, the alignment of the Fermi level, and the spatial distribution of the perturbed molecular orbitals are used to self-consistently explore the transport mechanism through oligoacenes.
文摘We have investigated the electron transport properties of a N24B24 molecule coupled to two metallic contacts with a combination of GW approximation and the non-equilibrium Green＇s- function technique. The calculations indicate that the four and three resonant tunneling peaks are seen for the density of states （DOS） curves in the cases of single and multiple atomic contacts, respectively. The off state and negative differential resistance （NDR） effect are observed in the I-V characteristics of the N24B24 molecule. The NDR behavior is also observed in voltages of about 354.5, 354, 354.6, and 354.3 V for one, four, six, and eight atomic contacts. Also, the I-V characteristics of N24B24 are in off state at low voltages that is independent of the contact types. The current contact types and indicate that N24B24 molecule curves against the gate voltage depend on behaves as a semiconductor.
基金supported by the National Natural Science Foundation of China(No.21643011)the Fundamental Research Foundations for the Central Universities(No.ZYGX2016J067)
文摘Motivated by the recent advances of transition-metal-nitrogen-carbon (TM-N-C) materials in catalysis, we investigate the electronic structure and transport properties of FeN3-embedded armchair and zigzag graphene nanoribbons (FeN3@AGNRs, FeN3@ZGNRs) with different widths. The first-principles results indicate that the FeN3 induces significant changes on the band structures of both ZGNRs and AGNRs, making the resultant systems quite different from the pristine ones and own room-temperature stable ferromagnetic (FM) ground states. While only FeN3@AGNRs possess a significant spin-dependent negative differential resistance (NDR) and a striking current polarization (nearly 100%) behaviors, due to that FeN3 introduces two isolated spin-down states, which contribute current with different performances when they couple with different frontier orbits. It is suggested that by embedding FeN3 complexes, AGNRs can be used to build spin devices in spintronics.
基金Supported by the National Natural Science Foundation of China under Grant No. 10832005the Program for Changjiang Scholars and Innovative Research Team in University under Grant No. IRT0730Program for International S&T Cooperation Program of China under Grant No. 2009DFA02320
文摘We investigate the electronic transport properties of atomic carbon chain-graphene junctions by using the density-functionla theory combining with the non-equilibrium Green＇s functions. The results show that the transport properties are sensitively dependent on the contact geometry of carbon chain. From the calculated I-V curve we find negative differential resistance （NDR） in the two types of junctions. The NDR can be considered as a result of molecular orbitals moving related to the bias window.
基金Supported by DST-FIST Project.financial support from DST-FIST, Government of India
文摘The effect of terminal groups on the electron transport through metal-molecule-metal system has been investigated using nonequilibrium Green's function (NEGF) formalism combined with extended Huckel theory (EHT). Au-molecule-Au junctions are constructed with borazine and BCN unit structure as core molecule and sulphur (S), oxygen (O), selenium (Se) and cyano-group (CN) as terminal groups. The electron transport characteristics of the borazine and BCN molecular systems are analyzed through the transmission spectra and the current-voltage curve. The results demonstrate that the terminal groups modifying the transport behaviors of these systems in a controlled way. Our result shows that, selenium is the best linker to couple borazine to Au electrode and oxygen is the best one to couple BCN to Au electrode. Furthermore, the results of borazine systems are compared with that of BCN molecular systems and are discussed. Simulation results show that the conductance through BCN molecular systems is four times larger than the borazine molecular systems. Negative differential resistance behavior is observed with borazine-CN system and the saturation feature appears in BCN systems.
基金supported by the State Key Project of Fundamental Research of the Ministry of Science and Technology(Grant No. 2010CB934400)the National Natural Science Foundation of China (Grant Nos.11104338,10934099,and 51021061)+1 种基金the International Collaborative Research Programs between NSFC and EPSRC of the United Kingdom(Grant No.10911130234)between NSFC and ANR of France(Grant No.F040803)
文摘Organic spintronics refers to control spin dependent transport through organic materials.In the last two decades,extraordinary development has been achieved for organic-spintronics.A series of theoretical and experimental studies have been done to reveal the mechanisms of spin dependent transport properties.The theoretical analysis is based on the non-equilibrium Green's function formalism provides a mathematical framework for solving the transmission coefficients in the Landauer formula from atomistic first principles without any phenomenological parameters.In this article,we provide a brief theoretical review on organic spintronics devices and device physics therein.
基金Supported by National Natural Science Foundation of China under Grant No.11274040the Program for New Century Excellent Talents in University under Grant No.NCET-08-0044
文摘We study the electron transport through a special quantum-dot(QD)structure composed of three QDs and two Majorana bound states(MBSs)using the nonequilibrium Green’s function technique.This QD-MBS ring structure includes two channels with the two coupled MBSs being Channel 1 and one QD being Channel 2,and three types of transport processes such as the electron transmission(ET),the Andreev reflection(AR),and the crossed Andreev reflection(CAR).By comparing the ET,AR,and CAR processes through Channels 1 and 2,we make a systematic study on the transport properties of the QD-MBS ring.It is shown that there appear two kinds of characteristic transport patterns for Channels 1 and 2,as well as the interplay between the two patterns.Of particular interest is that there exists an AR-assisted ET process in Channel 2,which is different from that in Channel 1.Thus a clear"X"pattern due to the ET and AR processes appears in the ET,AR,and CAR transmission coefficients.Moreover,we study how Channel 2 affects the three transport processes when Channel 1 is tuned in the ET and CAR regimes.It is shown that the transport properties of the ET,AR and CAR processes can be adjusted by tuning the energy level of the QD embedded in Channel 2.We believe this research should be a helpful reference for understanding the transport properties in the QD-MBS coupled systems.
