合金材料中结构转变的晶体相场法模拟

晶体相场方法被用于描述扩散时间尺度上的原子效应,在此基础上,Greenwood结合经典密度泛函理论,通过向自由能函数中引入一组两点相关函数,简化得到结构晶体相场方法。该方法可以用于研究多重组分合金材料的复杂微观结构。与经典密度泛函理论和一般晶体相场方法进行对比,详细论述了结构晶体相场模型的自由能函数以及两点相关函数。简要介绍了结构晶体相场方法在凝固过程、结构转变和复杂缺陷等方面的应用。

Characterization of Average Molecular Structure of Heavy Oil Fractions by ~1H Nuclear Magnetic Resonance and X-ray Diffraction

The chemical structure of heavy oil fractions obtained by liquid-solid adsorption chromatography was character-ized by 1 H nuclear magnetic resonance and X-ray diffraction.The molecular weight and molecular formula of asphaltene molecules were estimated by combining 1 H nuclear magnetic resonance and X-ray diffraction analyses,and were also ob-tained from vapor pressure osmometry and elemental analysis.Heteroatoms,such as S,N,and O atoms,were considered in the construction of average molecular structure of heavy oils.Two important structural parameters were proposed,including the number of alkyl chain substituents to aromatic rings and the number of total rings with heteroatoms.Ultimately,the av-erage molecular structures of polycyclic aromatics,heavy resins and asphaltene molecules were constructed.The number of α-,β-,γ-,and aromatic hydrogen atoms of the constructed average molecular structures fits well with the number of hydro-gen atoms derived from the experimental spectral data.

Joint inversion of gravity and multiple components of tensor gravity data

Geological structures often exhibit smooth characteristics away from sharp discontinuities. One aim of geophysical inversion is to recover information about the smooth structures as well as about the sharp discontinuities. Because no specific operator can provide a perfect sparse representation of complicated geological models, hyper-parameter regularization inversion based on the iterative split Bregman method was used to recover the features of both smooth and sharp geological structures. A novel preconditioned matrix was proposed, which counteracted the natural decay of the sensitivity matrix and its inverse matrix was calculated easily. Application of the algorithm to synthetic data produces density models that are good representations of the designed models. The results show that the algorithm proposed is feasible and effective.

Acute diverticulitis in younger patients:Any rationale for a different approach?

AIM:To compare the natural history and course of acute diverticulitis in a younger age group with an older population and to evaluate whether younger patients should be managed differently. METHODS:This study was a retrospective review of 157 patients treated with acute diverticulitis between January 1,2004 and December 31,2007.Diverticulitis was stratified according to the Hinchey classification. Patients were divided into 2 populations:group A≤ 50 years(n=31) ;group B>50 years(n=126) .Mean patient follow-up was 15 mo. RESULTS:The median age was 60 years.A significantly higher proportion of patients in group B presented with complicated diverticulitis(36.5%vs 12.9%,P=0.01) .Recurrence was more frequent in group A(25.8%vs 11.1%,P=0.03) and the mean time-torecurrence was shorter(12 mo vs 28 mo,P=0.26) . The most severe recurrent episodes of acute diverticulitis were classified as Hinchey stageⅠand none of the patients required emergency surgery.In multivariate analysis,only age(P=0.024) was identified as an independent prognostic factor for recurrence. CONCLUSION:Based on the results of this study,we recommend that diverticulitis management should be based on the severity of the disease and not on the age of the patient.

Relationship between Renying pulse augmentation index and Cunkou pulse condition in different blood pressure groups

OBJECTIVE： To explore the relationship between Renying pulse （carotid） augmentation index （AI） and Cunkou pulse condition in different blood pres- sure groups, and the clinical significance of Reny- ing and Cunkou pulse parameters to reflect vascu- lar function. METHODS： Eighty-six patients with essential hyper- tension （EH） and 52 individuals with normal blood pressure （control group） between and January 2012 were included September 2010 this study. Reny- ing pulse AI was examined by a new diagnostic tool （ALOKA ProSound Alpha 10） --wave intensity （Wl） that is calculated as the product of the deriva- tives of the simultaneously recorded blood pres- sure changes （dP/dt） and blood-flow-velocity changes （dU/dt）, while Cunkou pulse condition was detected by DDMX-100 Pulse Apparatus inboth EH and control groups. A multifactorial corre- lation analysis was performed for data analysis. RESULTS： After adjusting for potential confound- ing variables, in the EH group, AI was positively cor- related with ts, w2/t （rts=0.225, P〈0.05; rw2/t=0.230, P〈 0.05） and negatively correlated with hs, hs/hl and w2 （rhs=- 0.393,P〈0.01 ;rhs/l=- 0.444, P〈0.01 ;rw2=- 0.389, P〈0.01）. In the control group, AI was positively cor- related with t3, t4, ts and w, （rt3=0.595, P〈0.01; r,4= 0.292, P〈0.05; rt5=0.318, P〈0.05; rw1=0.541, P〈0.01） and negatively correlated with h1, h2, h3, Ad and A （rh1= - 0.368, P〈0.05; rh2= - 0.330, P〈0.05; rh3= - 0.327, P〈 0.05; rAd=- 0.322, P〈0.05; rA=- 0.410, P〈0.01）. In the total sample group （EH plus control group, n= 138）, AI was positively correlated with t, ts, w1 and w, （rt=0.257, P〈0.01; rt5=0.266, P〈0.01; rw1=0.184, P〈 0.05; rw/t=0.210, P〈0.05） and negatively correlated with hs, hs/hl, w2 and Ad （rhs= - 0.230, P〈0.01; rh5/h1= - 0.218, P〈0.05; rw2= - 0.267, P〈0.01; rAd= - 0.246, P〈0.01）. Multiple linear regression analysis was car- ried out to model the relationship （F=7.887, P〈 0.001）.CONCLUSION： Renying pulse AI can effectively pre- dict arterial stiffness in synchrony with the manifes- tations of Cunkou pulse in elderly patients with hy- pertension. Cunkou pulse apparatus is a valuable tool for evaluating AI in clinical practice, The close correlations reported above reflect the holistic con- cept of Traditional Chinese Medicine.