X Man - Academia.edu (original) (raw)
Papers by X Man
Journal of Physics: Condensed Matter
The trigonal CaAl2Si2-type structure CaMn2P2 has been reported undergoing an exotic first order p... more The trigonal CaAl2Si2-type structure CaMn2P2 has been reported undergoing an exotic first order phase transition at the critical temperature T N = 69.5 K. In this paper, we present the optical spectra for the ab-plane of CaMn2P2 single crystal from 300 K to 10 K for the first time. In the real part of the optical conductivity spectra σ 1(ω), a direct gap could be determined at all temperatures without any Drude term visible, i.e., the sample goes through the first order phase transition from one insulator state to the other insulator state. At higher energy, an asymmetric sharp interband transition peak appears in all σ 1(ω) spectra, which indicates a divergence of the joint density of states. This sharp peak could be well described by the two dimensional van Hove singularity function. In particular, this peak is very sensitive to the first order phase transition, especially the peak position E t whose the most prominent blue shift occurs only when the first order transition happens...
British Journal of Dermatology, 2020
Since cases first emerged in December 2019, COVID-19 (a type of coronavirus) has rapidly become p... more Since cases first emerged in December 2019, COVID-19 (a type of coronavirus) has rapidly become pandemic. This fast-tracked paper (published quickly) from China on COVID-19 is written by dermatologists at the epicentre of the outbreak in Wuhan. Dermatology clinic staff may be at risk because protective equipment is not routinely available, and skin lesions might possibly transmit the virus indirectly. These authors suggest preventive measures based on experience in this and previous coronavirus outbreaks. Online consultation for non-urgent patients reduces the numbers of patients attending clinics. Nurse-led triage, to identify patients with possible COVID-19, at the entrances of hospital and skin clinics directs patients with a cough or fever to a specific COVID-19 area and a dermatologist is consulted if the fever might be related to skin disease. Clinic staff wear N95 masks and observe hand hygiene during consultations. Patients are admitted to a ward only if routine blood tests and chest CT scans exclude COVID-19. Triage will not detect patients who are showing no symptoms but who are developing the disease, so the hospital should provide an on-call expert team to discuss inpatients suspected or diagnosed with COVID-19 and refer them to radiology, respiratory or intensive care colleagues as required. Confirmed cases are managed following local policies. Skin disorders in COVID-19 inpatients can usually be managed remotely using photographs, email and teleconferencing. If necessary a multidisciplinary team (a team of medical staff from different specialties) can meet in the clean area of the isolation ward. If the dermatologist must see the patient, all records should be provided in advance to minimise exposure time. With these precautions, as of 20th February 2020 no infected patients were detected in the Wuhan Dermatology Department.
British Journal of Dermatology, 2020
自 2019 年 12 月首次出现病例以来,COVID‐19(一种冠状病毒)迅速成为大流行病。这篇来自中国的关于 COVID‐19 的快速论文(很快发表的论文)是由疫情中心武汉的皮肤科医生撰写的。
British Journal of Dermatology, 2020
Journal of Non-Crystalline Solids, 2015
Amorphous and polycrystalline indium-zinc-oxide (IZO) transparent conductive films have been grow... more Amorphous and polycrystalline indium-zinc-oxide (IZO) transparent conductive films have been grown by pulsed laser deposition (PLD) technique using O 2 and Ar as background gas, respectively. The evolution of surface morphology and crystalline structure of the IZO films have been discussed in the frame of the kinetic molecular theory by considering the different kinetic energy loss and the surface migration of impinging particles in Ar and O 2 atmosphere, respectively. Hall measurements show that for amorphous IZO films the highest electron mobility can be as high as 51 cm 2 /Vs with the electron concentrations (N e) being 4.0 × 10 19 cm −3 and the resistivity being 3.1 × 10 −3 Ω cm. Temperature dependent Hall measurements indicate that when N e is b 10 19 cm −3 the dominant scattering mechanism is defect scattering, when N e is in the range of 10 19-10 20 cm −3 both the defects and the ionized impurity contribute to the carrier scatterings, and when N e is N 3.1 × 10 20 cm −3 the formation of a non-parabolic conduction band in IZO films plays the most important role in the carrier scattering. The variation of the optical band gaps in IZO films with N e was addressed by taking account of both the Burstein-Moss shift and the band-gap-narrowing effects. Additionally, all the amorphous IZO films are highly transparent (transmission N 85%) in the visible spectrum, which makes the IZO films suitable for transparent conducting applications.
Optics Express, 2002
White light interferometry has been adopted to measure distributed polarization coupling in high-... more White light interferometry has been adopted to measure distributed polarization coupling in high-birefringence waveguides. Since the coupling mode is weak compared to the exciting mode, the contrast ratio of the interferogram is very low. This will increase the difficulty of direct detection of the polarization coupling intensity. By rotating the angle between the polarization eigenmodes and the principal axis of the linear polarizer from 45°to 85°, the contrast ratio of the interferogram can be improved more than 10 times. As a result, the measurement sensitivity can be improved more than 100 times.
Procedia CIRP, 2013
Machining is a pervasive manufacturing process used in industries such as automotive, aerospace, ... more Machining is a pervasive manufacturing process used in industries such as automotive, aerospace, medical implants and oil and gas. Analysis of processes via physics-based modeling enables new and innovative designs for cutting tools, provides confidence of machined workpiece quality characteristics and allows reduction in machining cycle times and tooling costs. Progressively sophisticated analyses of machining processes have evolved with the inclusion of effects of full three-dimensional analysis of cutting tools and complex tool/workpiece kinematics. Detailed-level analysis of machined workpiece surfaces based on finite element method (FEM) allows prediction of residual stresses, work hardened layer depths and heat flow. However, with the increase in model sophistication has come with computational burden. This paper details a high performance computing (HPC) environment for finite element models used for machining analysis. First, the FEM model is reviewed and its extension to high core-count shared memory environments is described. Scaled performance improvements for up to forty cores are demonstrated and performance improvements documented. Next, an HPC cluster is designed and a specialized batch queuing software is implemented that allows submission, monitoring and management of large scale machining simulations. Finally, an infrastructure for delivering the HPC capability to customers through Software as a Service (SaaS) is introduced.
Journal of Materials Processing Technology, 2013
Material failure due to adiabatic shear banding is a characteristic feature of chip formation in ... more Material failure due to adiabatic shear banding is a characteristic feature of chip formation in machining of Ti-6Al-4V material. In this paper, an enhanced Zerilli-Armstrong (Z-A) based material flow stress model is developed by accounting for the effects of material failure mechanisms such as voids and micro-cracks on the material flow strength during shear band formation. These effects are captured via a multiplicative failure function in the constitutive material flow stress model. The strain and strain rate dependence of the material failure mechanism are explicitly modeled via the failure function. The five unknown constants of the failure function are calibrated using cutting force data and the entire model is verified using separate force, chip segmentation frequency and tool-chip contact length data from orthogonal cutting experiments reported by Cotterell and Byrne (2008a,b). Model predictions of these quantities based on the enhanced material model are shown to be in good agreement with experiments over a wide range of cutting conditions.
International Journal of Cancer, 2007
Mucins are aberrantly expressed in various malignancies. We immunohistochemistrically tested muci... more Mucins are aberrantly expressed in various malignancies. We immunohistochemistrically tested mucins expression (MUC1, MUC2 and MUC5AC) in EUS-FNA samples from pancreatic occupying lesions for the diagnostic utility. The prevalence of MUC1, MUC2 and MUC5AC expression in pancreatic cancers were 77.5% (31/40), 10.0% (4/40) and 80.0% (32/40), respectively, and in the benign pancreatic diseases 25% (4/16), 31.3% (5/16) and 43.8% (7/16). MUC1 and MUC5AC significantly overexpressed in pancreatic cancer, and MUC1 negatively related with tumor differentiation degree (p < 0.05). The prevalence of MUC1, MUC2 and MUC5AC expression in pancreatic mucinous neoplasms were 66.7% (12/18), 38.9% (7/18) and 88.9% (16/18), respectively, and in the pancreatic nonmucinous neoplasms 60.5% (23/38), 5.3% (2/38) and 57.9% (22/38). MUC2 and MUC5AC significantly overexpressed in pancreatic mucinous neoplasms, especially MUC2 in benign mucinous neoplasms (p < 0.05). Compared with cytology alone, the combination test of MUC11cytology, and MUC5AC1cytology could achieve higher sensitivity (85 vs. 65%, 100 vs. 65%) and accuracy (89.3% vs. 73.2%, 91.1% vs. 73.2%) for pancreatic cancer diagnosis; the combination test of MUC2 1 cytology, and MUC5AC 1 cytology could achieve higher sensitivity (77.8% vs. 38.9%, 100% vs. 38.9%), and specificity (97.4% vs. 60.5%, 71.1% vs. 60.5%) accuracy (100% vs. 51.8%, 80.4% vs. 51.8%) for mucinous neoplasm diagnosis. The panel MUC11/MUC22/MUC5AC1/ was higher specific in pancreatic cancer diagnosis, as well as MUC12/MUC21/MUC5AC1/ in pancreatic mucinous neoplasms. Our observations suggest the mucins expression profile in EUS-FNA specimens has higher value for the diagnosis of pancreatic cancer and mucinous neoplasms.
Combustion and Flame, 2013
Ignition delay times of the three C5 primary alcohol isomers (n-pentanol, iso-pentanol and 2-meth... more Ignition delay times of the three C5 primary alcohol isomers (n-pentanol, iso-pentanol and 2-methyl-1butanol) were measured behind reflected shock waves. Experiments were conducted in the temperature range of 1100-1500 K, pressures of 1.0 and 2.6 atm, equivalence ratios of 0.25, 0.5 and 1.0, and O 2 concentration in the fuel/O 2 /Ar mixtures varying from 3.75% to 15%. Measurements show that the ignition delay time and the global activation energy of the three isomers both decrease in the order of isopentanol, 2-methyl-1-butanol, and n-pentanol. Chemical kinetic mechanisms for n-pentanol (Mech NP) and iso-pentanol (Mech IP), recently developed by Dagaut and co-workers, were used to model the respective ignition delay times. Results show that Mech NP yields close agreement at the equivalence ratio of 0.25, but the agreement is moderated with increasing equivalence ratio. Mech IP yields fairly close agreements at relatively higher temperatures but over-predicts the measurements by 50% at relatively lower temperatures for the three equivalence ratios studied. A new 2-methyl-1-butanol high temperature mechanism was proposed and validated against the ignition delay data. Sensitivity analysis for both n-pentanol and iso-pentanol showed the dominance of small radical reactions. Reaction pathway analysis aided further scrutiny of the fuel-specific reactions in Mech NP, leading to refinement of the kinetic model, and improved agreement between the predicted and measured ignition delay times as well as the jet-stirred reactor results.
Chinese Science Bulletin, 2011
Ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures with hydrogen amount-of-substan... more Ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures with hydrogen amount-of-substance fractions ranging from 0-20% were measured in a shock tube facility. The ambient temperature varied from 1422 to 1877 K and the pressure was maintained at 0.4 MPa behind the reflected shock wave. The experiments were conducted at an equivalence ratio of 2.0. The fuel mixtures were diluted with nitrogen gas so that the nitrogen amount-of-substance fraction was 95%. The experimental ignition delay time of the CH 4 /H 2 mixture decreased as the hydrogen amount-of-substance fraction increased. The enhancement of ignition by hydrogen addition was weak when the ambient temperature was >1750 K, and strong when the temperature was <1725 K. The ignition delay time of 20% H 2 /80% CH 4 was only one-third that of 100% CH 4 at 1500 K. A modified model based on GRI-Mech 3.0 was proposed and used to calculate the ignition delay times of test mixtures. The calculated results agreed with the experimental ignition delay times. Normalized sensitivity analysis showed that HO•+H 2 →H•+H 2 O was the main reaction for the formation of the H• at 1400 K. As the hydrogen amount-of-substance fraction increased, chain branching was enhanced through the reaction H•+O 2 →O•+HO•, and this reduced the ignition delay time. At 1800 K, the methyl radical (H 3 C•) became the key species that influenced the ignition of the CH 4 /H 2 /O 2 /N 2 mixtures, and sensitivity coefficients of the chain termination reaction 2H 3 C•(+M)→C 2 H 6 (+M), and chain propagation reaction HO 2 +H 3 C•→HO•+CH 3 O decreased, which reduced the influence of hydrogen addition on the ignition of the CH 4 /H 2 mixtures.
Alimentary Pharmacology & Therapeutics, 2010
Dyspepsia and irritable bowel syndrome (IBS) are common in Western populations. To determine the ... more Dyspepsia and irritable bowel syndrome (IBS) are common in Western populations. To determine the epidemiology of dyspepsia and IBS in China. A representative sample of 18 000 adults from five regions of China were asked to complete the modified Rome II questionnaire; 20% were asked to complete the 36-item Short Form Health Survey (SF-36). Participants from Shanghai were invited to provide blood samples and undergo oesophago-gastroduodenoscopy. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined using a multivariate logistic regression model. The survey was completed by 16 091 individuals (response rate: 89.4%). Overall, 387 participants (2.4%) had dyspepsia and 735 (4.6%) had IBS. All SF-36 dimension scores were at least five points lower in individuals with than without dyspepsia or IBS (P < or = 0.001). In Shanghai, 1030 (32.7%) of the 3153 respondents agreed to endoscopy; neither dyspepsia nor IBS was found to be associated with reflux oesophagitis, peptic ulcer disease or Helicobacter pylori infection. Prevalence estimates for dyspepsia and IBS in China are lower than in Western populations. In China, dyspepsia or IBS symptoms are generally not associated with underlying organic disease.
Journal of Physics: Condensed Matter
The trigonal CaAl2Si2-type structure CaMn2P2 has been reported undergoing an exotic first order p... more The trigonal CaAl2Si2-type structure CaMn2P2 has been reported undergoing an exotic first order phase transition at the critical temperature T N = 69.5 K. In this paper, we present the optical spectra for the ab-plane of CaMn2P2 single crystal from 300 K to 10 K for the first time. In the real part of the optical conductivity spectra σ 1(ω), a direct gap could be determined at all temperatures without any Drude term visible, i.e., the sample goes through the first order phase transition from one insulator state to the other insulator state. At higher energy, an asymmetric sharp interband transition peak appears in all σ 1(ω) spectra, which indicates a divergence of the joint density of states. This sharp peak could be well described by the two dimensional van Hove singularity function. In particular, this peak is very sensitive to the first order phase transition, especially the peak position E t whose the most prominent blue shift occurs only when the first order transition happens...
British Journal of Dermatology, 2020
Since cases first emerged in December 2019, COVID-19 (a type of coronavirus) has rapidly become p... more Since cases first emerged in December 2019, COVID-19 (a type of coronavirus) has rapidly become pandemic. This fast-tracked paper (published quickly) from China on COVID-19 is written by dermatologists at the epicentre of the outbreak in Wuhan. Dermatology clinic staff may be at risk because protective equipment is not routinely available, and skin lesions might possibly transmit the virus indirectly. These authors suggest preventive measures based on experience in this and previous coronavirus outbreaks. Online consultation for non-urgent patients reduces the numbers of patients attending clinics. Nurse-led triage, to identify patients with possible COVID-19, at the entrances of hospital and skin clinics directs patients with a cough or fever to a specific COVID-19 area and a dermatologist is consulted if the fever might be related to skin disease. Clinic staff wear N95 masks and observe hand hygiene during consultations. Patients are admitted to a ward only if routine blood tests and chest CT scans exclude COVID-19. Triage will not detect patients who are showing no symptoms but who are developing the disease, so the hospital should provide an on-call expert team to discuss inpatients suspected or diagnosed with COVID-19 and refer them to radiology, respiratory or intensive care colleagues as required. Confirmed cases are managed following local policies. Skin disorders in COVID-19 inpatients can usually be managed remotely using photographs, email and teleconferencing. If necessary a multidisciplinary team (a team of medical staff from different specialties) can meet in the clean area of the isolation ward. If the dermatologist must see the patient, all records should be provided in advance to minimise exposure time. With these precautions, as of 20th February 2020 no infected patients were detected in the Wuhan Dermatology Department.
British Journal of Dermatology, 2020
自 2019 年 12 月首次出现病例以来,COVID‐19(一种冠状病毒)迅速成为大流行病。这篇来自中国的关于 COVID‐19 的快速论文(很快发表的论文)是由疫情中心武汉的皮肤科医生撰写的。
British Journal of Dermatology, 2020
Journal of Non-Crystalline Solids, 2015
Amorphous and polycrystalline indium-zinc-oxide (IZO) transparent conductive films have been grow... more Amorphous and polycrystalline indium-zinc-oxide (IZO) transparent conductive films have been grown by pulsed laser deposition (PLD) technique using O 2 and Ar as background gas, respectively. The evolution of surface morphology and crystalline structure of the IZO films have been discussed in the frame of the kinetic molecular theory by considering the different kinetic energy loss and the surface migration of impinging particles in Ar and O 2 atmosphere, respectively. Hall measurements show that for amorphous IZO films the highest electron mobility can be as high as 51 cm 2 /Vs with the electron concentrations (N e) being 4.0 × 10 19 cm −3 and the resistivity being 3.1 × 10 −3 Ω cm. Temperature dependent Hall measurements indicate that when N e is b 10 19 cm −3 the dominant scattering mechanism is defect scattering, when N e is in the range of 10 19-10 20 cm −3 both the defects and the ionized impurity contribute to the carrier scatterings, and when N e is N 3.1 × 10 20 cm −3 the formation of a non-parabolic conduction band in IZO films plays the most important role in the carrier scattering. The variation of the optical band gaps in IZO films with N e was addressed by taking account of both the Burstein-Moss shift and the band-gap-narrowing effects. Additionally, all the amorphous IZO films are highly transparent (transmission N 85%) in the visible spectrum, which makes the IZO films suitable for transparent conducting applications.
Optics Express, 2002
White light interferometry has been adopted to measure distributed polarization coupling in high-... more White light interferometry has been adopted to measure distributed polarization coupling in high-birefringence waveguides. Since the coupling mode is weak compared to the exciting mode, the contrast ratio of the interferogram is very low. This will increase the difficulty of direct detection of the polarization coupling intensity. By rotating the angle between the polarization eigenmodes and the principal axis of the linear polarizer from 45°to 85°, the contrast ratio of the interferogram can be improved more than 10 times. As a result, the measurement sensitivity can be improved more than 100 times.
Procedia CIRP, 2013
Machining is a pervasive manufacturing process used in industries such as automotive, aerospace, ... more Machining is a pervasive manufacturing process used in industries such as automotive, aerospace, medical implants and oil and gas. Analysis of processes via physics-based modeling enables new and innovative designs for cutting tools, provides confidence of machined workpiece quality characteristics and allows reduction in machining cycle times and tooling costs. Progressively sophisticated analyses of machining processes have evolved with the inclusion of effects of full three-dimensional analysis of cutting tools and complex tool/workpiece kinematics. Detailed-level analysis of machined workpiece surfaces based on finite element method (FEM) allows prediction of residual stresses, work hardened layer depths and heat flow. However, with the increase in model sophistication has come with computational burden. This paper details a high performance computing (HPC) environment for finite element models used for machining analysis. First, the FEM model is reviewed and its extension to high core-count shared memory environments is described. Scaled performance improvements for up to forty cores are demonstrated and performance improvements documented. Next, an HPC cluster is designed and a specialized batch queuing software is implemented that allows submission, monitoring and management of large scale machining simulations. Finally, an infrastructure for delivering the HPC capability to customers through Software as a Service (SaaS) is introduced.
Journal of Materials Processing Technology, 2013
Material failure due to adiabatic shear banding is a characteristic feature of chip formation in ... more Material failure due to adiabatic shear banding is a characteristic feature of chip formation in machining of Ti-6Al-4V material. In this paper, an enhanced Zerilli-Armstrong (Z-A) based material flow stress model is developed by accounting for the effects of material failure mechanisms such as voids and micro-cracks on the material flow strength during shear band formation. These effects are captured via a multiplicative failure function in the constitutive material flow stress model. The strain and strain rate dependence of the material failure mechanism are explicitly modeled via the failure function. The five unknown constants of the failure function are calibrated using cutting force data and the entire model is verified using separate force, chip segmentation frequency and tool-chip contact length data from orthogonal cutting experiments reported by Cotterell and Byrne (2008a,b). Model predictions of these quantities based on the enhanced material model are shown to be in good agreement with experiments over a wide range of cutting conditions.
International Journal of Cancer, 2007
Mucins are aberrantly expressed in various malignancies. We immunohistochemistrically tested muci... more Mucins are aberrantly expressed in various malignancies. We immunohistochemistrically tested mucins expression (MUC1, MUC2 and MUC5AC) in EUS-FNA samples from pancreatic occupying lesions for the diagnostic utility. The prevalence of MUC1, MUC2 and MUC5AC expression in pancreatic cancers were 77.5% (31/40), 10.0% (4/40) and 80.0% (32/40), respectively, and in the benign pancreatic diseases 25% (4/16), 31.3% (5/16) and 43.8% (7/16). MUC1 and MUC5AC significantly overexpressed in pancreatic cancer, and MUC1 negatively related with tumor differentiation degree (p < 0.05). The prevalence of MUC1, MUC2 and MUC5AC expression in pancreatic mucinous neoplasms were 66.7% (12/18), 38.9% (7/18) and 88.9% (16/18), respectively, and in the pancreatic nonmucinous neoplasms 60.5% (23/38), 5.3% (2/38) and 57.9% (22/38). MUC2 and MUC5AC significantly overexpressed in pancreatic mucinous neoplasms, especially MUC2 in benign mucinous neoplasms (p < 0.05). Compared with cytology alone, the combination test of MUC11cytology, and MUC5AC1cytology could achieve higher sensitivity (85 vs. 65%, 100 vs. 65%) and accuracy (89.3% vs. 73.2%, 91.1% vs. 73.2%) for pancreatic cancer diagnosis; the combination test of MUC2 1 cytology, and MUC5AC 1 cytology could achieve higher sensitivity (77.8% vs. 38.9%, 100% vs. 38.9%), and specificity (97.4% vs. 60.5%, 71.1% vs. 60.5%) accuracy (100% vs. 51.8%, 80.4% vs. 51.8%) for mucinous neoplasm diagnosis. The panel MUC11/MUC22/MUC5AC1/ was higher specific in pancreatic cancer diagnosis, as well as MUC12/MUC21/MUC5AC1/ in pancreatic mucinous neoplasms. Our observations suggest the mucins expression profile in EUS-FNA specimens has higher value for the diagnosis of pancreatic cancer and mucinous neoplasms.
Combustion and Flame, 2013
Ignition delay times of the three C5 primary alcohol isomers (n-pentanol, iso-pentanol and 2-meth... more Ignition delay times of the three C5 primary alcohol isomers (n-pentanol, iso-pentanol and 2-methyl-1butanol) were measured behind reflected shock waves. Experiments were conducted in the temperature range of 1100-1500 K, pressures of 1.0 and 2.6 atm, equivalence ratios of 0.25, 0.5 and 1.0, and O 2 concentration in the fuel/O 2 /Ar mixtures varying from 3.75% to 15%. Measurements show that the ignition delay time and the global activation energy of the three isomers both decrease in the order of isopentanol, 2-methyl-1-butanol, and n-pentanol. Chemical kinetic mechanisms for n-pentanol (Mech NP) and iso-pentanol (Mech IP), recently developed by Dagaut and co-workers, were used to model the respective ignition delay times. Results show that Mech NP yields close agreement at the equivalence ratio of 0.25, but the agreement is moderated with increasing equivalence ratio. Mech IP yields fairly close agreements at relatively higher temperatures but over-predicts the measurements by 50% at relatively lower temperatures for the three equivalence ratios studied. A new 2-methyl-1-butanol high temperature mechanism was proposed and validated against the ignition delay data. Sensitivity analysis for both n-pentanol and iso-pentanol showed the dominance of small radical reactions. Reaction pathway analysis aided further scrutiny of the fuel-specific reactions in Mech NP, leading to refinement of the kinetic model, and improved agreement between the predicted and measured ignition delay times as well as the jet-stirred reactor results.
Chinese Science Bulletin, 2011
Ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures with hydrogen amount-of-substan... more Ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures with hydrogen amount-of-substance fractions ranging from 0-20% were measured in a shock tube facility. The ambient temperature varied from 1422 to 1877 K and the pressure was maintained at 0.4 MPa behind the reflected shock wave. The experiments were conducted at an equivalence ratio of 2.0. The fuel mixtures were diluted with nitrogen gas so that the nitrogen amount-of-substance fraction was 95%. The experimental ignition delay time of the CH 4 /H 2 mixture decreased as the hydrogen amount-of-substance fraction increased. The enhancement of ignition by hydrogen addition was weak when the ambient temperature was >1750 K, and strong when the temperature was <1725 K. The ignition delay time of 20% H 2 /80% CH 4 was only one-third that of 100% CH 4 at 1500 K. A modified model based on GRI-Mech 3.0 was proposed and used to calculate the ignition delay times of test mixtures. The calculated results agreed with the experimental ignition delay times. Normalized sensitivity analysis showed that HO•+H 2 →H•+H 2 O was the main reaction for the formation of the H• at 1400 K. As the hydrogen amount-of-substance fraction increased, chain branching was enhanced through the reaction H•+O 2 →O•+HO•, and this reduced the ignition delay time. At 1800 K, the methyl radical (H 3 C•) became the key species that influenced the ignition of the CH 4 /H 2 /O 2 /N 2 mixtures, and sensitivity coefficients of the chain termination reaction 2H 3 C•(+M)→C 2 H 6 (+M), and chain propagation reaction HO 2 +H 3 C•→HO•+CH 3 O decreased, which reduced the influence of hydrogen addition on the ignition of the CH 4 /H 2 mixtures.
Alimentary Pharmacology & Therapeutics, 2010
Dyspepsia and irritable bowel syndrome (IBS) are common in Western populations. To determine the ... more Dyspepsia and irritable bowel syndrome (IBS) are common in Western populations. To determine the epidemiology of dyspepsia and IBS in China. A representative sample of 18 000 adults from five regions of China were asked to complete the modified Rome II questionnaire; 20% were asked to complete the 36-item Short Form Health Survey (SF-36). Participants from Shanghai were invited to provide blood samples and undergo oesophago-gastroduodenoscopy. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined using a multivariate logistic regression model. The survey was completed by 16 091 individuals (response rate: 89.4%). Overall, 387 participants (2.4%) had dyspepsia and 735 (4.6%) had IBS. All SF-36 dimension scores were at least five points lower in individuals with than without dyspepsia or IBS (P < or = 0.001). In Shanghai, 1030 (32.7%) of the 3153 respondents agreed to endoscopy; neither dyspepsia nor IBS was found to be associated with reflux oesophagitis, peptic ulcer disease or Helicobacter pylori infection. Prevalence estimates for dyspepsia and IBS in China are lower than in Western populations. In China, dyspepsia or IBS symptoms are generally not associated with underlying organic disease.