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1,419 result(s) for "Zhang, Shu Yin"
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Wood density and wood shrinkage in relation to initial spacing and tree growth in black spruce (Picea mariana)
This study has quantified basic wood density and various types of wood shrinkage in relation to initial spacing (or initial planting density) and tree growth based on a 48-year-old black spruce ( Picea mariana ) spacing trial in eastern Canada. A total of 139 sample trees were collected from four initial spacings (3086, 2500, 2066, 1372 trees/ha) for this study. Analyses of variance (ANOVA) show that initial spacing is the most important parameter affecting wood density significantly, followed by tree diameter at breast height (DBH) class. With increasing spacing, wood density, radial and volumetric shrinkage tend to decrease, whereas longitudinal shrinkage tends to increase gradually. The largest spacing has the lowest wood density, the smallest transverse shrinkage and the largest longitudinal shrinkage. Path analysis indicates that wood density is the most important parameter affecting transverse shrinkage, followed by the distance from the pith. Furthermore, much of the variation of the transverse shrinkage with wood density may be due to the initial spacing and tree DBH class. Path analysis also reveals that longitudinal shrinkage is mainly related to log height and tree DBH class. With increasing log height, longitudinal shrinkage tends to increase, and transverse shrinkage tends to decrease. With increasing DBH class, the trees tend to have an increasing longitudinal shrinkage and a decreasing transverse shrinkage. Overall, this study suggests that a large increase in the initial spacing (e.g., 1372 trees/ha) might lead to a significant reduction in both wood density and transverse shrinkage, and a significant increase in longitudinal shrinkage in black spruce.
Selection for Both Growth and Wood Properties in Hybrid Poplar Clones
Abstract To better understand the genetic control of growth and wood properties in hybrid poplar (Populus spp.), genetic relationships of selected wood properties with growth traits were examined in a 3-yr-old clonal trial located in Windsor and St-Ours, southern Quebec, Canada. In total, 371 trees from 21 hybrid poplar clones were sampled at the two locations. Clonal effects are stronger than growth traits effects on wood density and initial moisture content. The estimated clonal repeatability for wood density (0.92) and initial moisture content (0.80) across the two sites are thus considerably higher than for dbh (0.64) and tree height (0.72). Neither wood density nor mean fiber length were found to significantly correlate with growth traits. This suggests that in the hybrid poplar clones selection for growth traits will not result in a significant reduction in the wood quality traits. Selection for stem dry fiber weight appears to be an optimal selection strategy, as it will lead to the highest genetic gain in stem dry fiber yield, or maximum fiber production while wood density is improved.
Identification of selected internal wood characteristics in computed tomography images of black spruce Picea mariana: A comparison study
The feasibility of identifying internal wood characteristics in computed tomography (CT) images of black spruce was investigated using two promising classifiers: the maximum likelihood classifier (MLC) and the back propagation (BP) artificial neural network (ANN) classifier. Nine image features including one spectral feature (gray level values), a distance feature, and seven textural features were employed to develop the classifiers. The selected internal wood characteristics to be identified included heartwood, sapwood, bark, and knots. Twenty cross-sectional CT images of a black spruce log were randomly selected to develop the two classifiers. The results suggest that both classifiers produced high classification accuracy. Compared with the MLC classifier (80.9% overall accuracy), the BP ANN classifier had better classification performance (97.6% overall accuracy). Moreover, statistical analysis reveals that the heartwood of the black spruce log used in this study is the easiest to identify by either classifier compared with the other three log features. The results also suggest that the separability of one wood characteristic from the other wood characteristics in black spruce CT images is mainly related to moisture content.
Effects of Traditional Chinese Medicine Shensong Yangxin Capsules on Heart Rhythm and Function in Congestive Heart Failure Patients with Frequent Ventricular Premature Complexes:A Randomized, Double-blind, Multicenter Clinical Trial
Background:Pharmacological therapy for congestive heart failure (CHF) with ventricular arrhythmia is limited.In the study,our aim was to evaluate the effects of Chinese traditional medicine Shensong Yangxin capsules (SSYX) on heart rhythm and function in CHF patients with frequent ventricular premature complexes (VPCs).Methods:This double-blind,placebo-controlled,multicenter study randomized 465 CHF patients with frequent VPCs to the SSYX (n =232) and placebo groups (n =233) for 12 weeks of treatment.The primary endpoint was the VPCs monitored by a 24-h ambulatory electrocardiogram.The secondary endpoints included the left ventricular ejection fraction (LVEF),left ventricular end-diastolic diameter,N-terminal pro-brain natriuretic peptide (NT-proBNP),New York Heart Association (NYHA) classification,6-min walking distance (6MWD),Minnesota Living with Heart Failure Questionnaire (MLHFQ) scores,and composite cardiac events (CCEs).Results:The clinical characteristics were similar at baseline.SSYX caused a significantly greater decline in the total number of VPCs than the placebo did (-2145 ± 2848 vs.-841 ± 3411,P 〈 0.05).The secondary endpoints of the LVEE NYHA classification,NT-proBNP,6MWD,and MLHFQ scores showed a greater improvements in the SSYX group than in the placebo group (ALVEF at 12th week:4.75 ± 7.13 vs.3.30 ± 6.53;NYHA improvement rate at the 8th and 12th week:32.6% vs.21.8%,40.5% vs.25.7%;mean level of NT-proBNP in patients with NT-proBNP 〉125 pg/ml at 12th week:-122 [Q1,Q3:-524,0] vs.-75 [Q1,Q3:-245,0];A6MWD at 12th week:35.1 ± 38.6 vs.17.2 ± 45.6;AMLHFQ at the 4th,8th,and 12th week:-4.24 ± 6.15 vs.-2.31 ± 6.96,-8.l 9 ± 8.41 vs.-3.25 ± 9.40,10.60 ± 9.41 vs.-4.83 ± 11.23,all P 〈 0.05).CCEs were not different between the groups during the study period.Conclusions:In this 12-week pilot study,SSYX was demonstrated to have the benefits of VPCs suppression and cardiac function improvement with good compliance on a background of standard treatment for CHF.
Mechanical and fatigue properties of self-piercing riveted joints in high-strength steel and aluminium alloy
Static tensile and fatigue tests were performed on shear and tensile self-piercing riveted aluminium-steel structures to evaluate their mechanical and fatigue properties. The influences of the thickness and the strength of the high strength steel on mechanical and fatigue performances were investigated based on the tensile and F-N curves of the joints. The results show that mechanical and fatigue properties of the shear self-piercing riveted joints are much better than those of the tensile self-piercing riveted joints. Mechanical and fatigue performances of the two joints were significantly influenced by the thickness and strength of the steel sheet, and were markedly improved when the thickness of steel sheet increased. The steel strength showed significantly different effects on shear and tensile riveted structures, i. e. , when the steel strength increased, the strength of the shear structure greatly increased while the tensile structure just had a slight increase in the strength. Fatigue failure generally occurred in the sheet materials and the fatigue crack location changed with increasing the sheet thickness and the sheet strength.
Comparing of Light Transmittance Aggregometry and Modified Thrombelastograph in Predicting Clinical Outcomes in Chinese Patients Undergoing Coronary Stenting with Clopidogrel
Background: Several platelet function tests are currently used to measure responsiveness to antiplatelet therapy. This study was to compare two tests, light transmittance aggregometry (LTA) and modified thrombelastography (mTEG), for predicting clinical outcomes in Chinese patients after percutaneous coronary intervention (PCI). Methods: Prospective, observational, single-center study of 789 Chinese patients undergoing PCI was enrolled. This study was investigated the correlations between the two tests and performed receiver operating characteristic curve (ROC) analysis for major adverse cardiovascular events (MACEs) at 1-year follow-up. Results: MACEs occurred in 32 patients (4.1%). Correlations were well between the two tests in the adenosine diphosphate induced platelet reactivity (Spearman r = 0.733, P 〈 0.001 ). ROC-curve analysis demonstrated that LTA (area under the curve [AUC]: 0.677; 95% confidence interval [CO: 0.643-0.710; P = 0.0009), and mTEG (AUC: 0.684; 95% CI: 0.650-0.716; P = 0.0001) had moderate ability to discriminate between patients with and without MACE. MACE occurred more frequently in patients with high on-treatment platelet reactivity (HPR) when assessed by LTA (7.4% vs. 2.7%; P 〈 0.001), and by TEG (6.7% vs. 2.6%; P 〈 0.001 ). Kaplan-Meier analysis demonstrated that HPR based on the LTA and mTEG was associated with almost 3-fold increased risk of MACE at 1-year follow-up. Conclusions: The correlation between LTA and mTEG is relatively high in Chinese patients. HPR measured by LTA and mTEG were significantly associated with MACE in Chinese patients undergoing PCI.
Mechanical and fatigue properties of self-piercing riveted joints in high-strength steel and aluminium alloy
Static tensile and fatigue tests were performed on shear and tensile self-piercing riveted aluminium-steel structures to evaluate their mechanical and fatigue properties. The influences of the thickness and the strength of the highstrength steel on mechanical and fatigue performances were investigated based on the tensile and F-N curves of the joints. The results show that mechanical and fatigue properties of the shear self-piercing riveted joints are much better than those of the tensile self-piercing riveted joints. Mechanical and fatigue performances of the two joints were significantly influenced by the thickness and strength of the steel sheet,and were markedly improved when the thickness of steel sheet increased. The steel strength showed significantly different effects on shear and tensile riveted structures,i. e.,when the steel strength increased,the strength of the shear structure greatly increased while the tensile structure just had a slight increase in the strength. Fatigue failure generally occurred in the sheet materials and the fatigue crack location changed with increasing the sheet thickness and the sheet strength.
Highly lipophilic 3-epi-betulinic acid derivatives as potent and selective TGR5 agonists with improved cellular efficacy
Aim: TGR5 is a G protein-coupled receptor that is expressed in intestinal L-cells and stimulates glucagon-like peptide 1(GLP-1) secretion. TGR5 may represent a novel target for the treatment of metabolic disorder. Here, we sought to design and synthesize a series of TGR5 agonists derived from the natural product betuiinic acid. Methods: A series of betulinic acid derivatives were designed and synthesized. A cAMP assay was established using a HEK293 cell line expressing human TGR5. Luciferase reporter assay was established using HEK293 cells transfected with plasmids encoding human FXR and luciferase reporter. A human intestinal L-cell line NCI-H716 was used to evaluate the effects of the betulinic acid derivatives on GLP-1 secretion in vitro. Results; Biological data revealed that the 3-a-OH triterpenoids consistently show increased potency for TGR5 compared to their 3-β- OH epimers. 3-OH esterification increased the lipophilicity and TGR5 activity of 3-cc betulinic derivatives and enhanced the activity differences between 3-α and 3-β derivatives. The 3-α-acyloxy betulinic acids also exhibited a significant dose-dependent GLP-1 secretion effect. Conclusion: This study demonstrates that highly lipophilic 3-epi-betulinic acid derivatives can be potent and selective TGR5 agonists with improved cellular efficacy, and our research here provides a new strategy for the design and development of potent TGR5 agonists.
Numerical investigation of relationship between water contact angle and drag reduction ratio of superhydrophobic surfaces
This paper proposes a novel bubble model to analyze drag reduction. The relationship between the slip length and air bubble height is discussed. The numerical relationship between the surface contact angle and slip length is obtained using the solid-liquid contact ratio in the Cassie equation. The surface drag reduction ratio i~:creases by 40~ at low velocities when the solid liquid contact ratio decreases from 90% to i0%. An experimental setup to study liquid/solid friction drag is reported. The drag reduction ratio for the superhydrophobic surface tested experimentally is 30~-35~ at low velocities. These results are skailar to the simulation results obtained at low velocities.
Impact of Proton-pump Inhibitors on the Pharmacodynamic Effect and Clinical Outcomes in Patients Receiving Dual Antiplatelet Therapy after Percutaneous Coronary Intervention: A Propensity Score Analysis
Background:Prior studies have reported controversial conclusions regarding the risk of adverse cardiovascular events in patients using proton-pump inhibitors (PPIs) combined with clopidogrel therapy,causing much uncertainty in clinical practice.We sought to evaluate the safety of PPIs use among high-risk cardiovascular patients who underwent percutaneous coronary intervention (PCI) in a long-term follow-up study.Methods:A total of 7868 consecutive patients who had undergone PCI and received dual antiplatelet therapy (DAPT) at a single center from January 2013 to December 2013 were enrolled.Adenosine diphosphate (ADP)-induced platelet aggregation inhibition was measured by modified thromboelastography (mTEG) in 5042 patients.Propensity score matching (PSM) was applied to control differing baseline factors.Cox proportional hazards regression was used to evaluate the 2-year major adverse cardiovascular and cerebrovascular events (MACCEs),as well as individual events,including all-cause death,myocardial infarction,unplanned target vessel revascularization,stent thrombosis,and stroke.Results:Among the whole cohort,27.2% were prescribed PPIs.The ADP-induced platelet aggregation inhibition by mTEG was significantly lower in PPI users than that in non-PPI users (42.0 ± 30.9% vs.46.4 ± 31.4%,t =4.435,P 〈 0.001).Concomitant PPI use was not associated with increased MACCE through 2-year follow-up (12.7% vs.12.5%,x2 =0.086,P =0.769).Other endpoints showed no significant differences after multivariate adjustment,regardless of PSM.Conclusion:In this large cohort of real-world patients,the combination of PPIs with DAPT was not associated with increased risk of MACCE in patients who underwent PCI at up to 2 years of follow-up.