Effect of anisotropy on deformation and crack formation under the brittle removal of 6H-SiC during SPDT process.

INTRODUCTION: Monocrystal SiC is representative of the third generation semiconductor materials, the efficient process technology of 6H-SiC wafer have always been a hot topic. Developing a SPDT processing method based on brittle removal mode with controllable surface/subsurface damage is an important approach to solve the processing difficulties of 6H-SiC. OBJECTIVES: This work aims to analyze the brittle removal process and fully explain the brittle separation behavior and deformation mechanism of 6H-SiC. The micro-scale crack propagation and the effect of anisotropy on crack distribution during machining process are investigated. METHODS: Large-scale molecular dynamics simulation was used in this work. RESULTS: Under the condition of brittle removal, shear fracture occurs in the front area of tool tip. Shear plane is high-index surface, independent of slip system. The location of tensile fracture is the cleavage plane of hexagonal system, and the fracture surface is composed of step-like joint planes or perfect plane structures. Cracks with self-healing capability appear in the area behind the tool when the surface to be machined is basal plane. When the surface to be machined is not basal plane, a large number of dislocations or cracks remain in subsurface region. Under brittle removal mode, a large amount of plastic deformation appears as well, and deformation mode is related to processing scheme. CONCLUSION: The brittle removal behavior of 6H-SiC under SPDT process has obvious anisotropy. Basal plane is more suitable for brittle removal of 6H-SiC without residual damage such as sub-surface cracks. The crack behind the tool generated by cleavage fracture can be repaired by itself. Fracture behavior is not related to dislocation. The processing method parallel to the c-axis can cause the generation of a large number of surface cracks. The (011¯0)/[21¯1¯0] and (112¯0)/[11¯00] mode is the best way to achieve plastic removal of 6H-SiC during SPDT process.

Protocol to monitor cardiac function and hemodynamics in septic rodents.

Septic cardiomyopathy is associated with high mortality in septic patients, characterized by reversible systolic and diastolic dysfunction. It is essential to monitor cardiac function and hemodynamic changes in septic animals. Here, we present a protocol to monitor cardiac function and hemodynamics in septic rodents. We describe steps for performing cecal ligation and puncture on rodents to induce sepsis, acquiring two-dimensional echocardiographic and M-mode ultrasonic images, and assessing mean arterial pressure in septic animals. For complete details on the use and execution of this protocol, please refer to Zhang et al.1.

Microglial Activation: Key Players in Sepsis-Associated Encephalopathy.

Sepsis-associated encephalopathy (SAE) is a common brain dysfunction, which results in severe cognitive and neurological sequelae and an increased mortality rate in patients with sepsis. Depending on the stimulus, microglia (resident macrophages in the brain that are involved in SAE pathology and physiology) can adopt two polarization states (M1/M2), corresponding to altered microglial morphology, gene expression, and function. We systematically described the pathogenesis, morphology, function, and phenotype of microglial activation in SAE and demonstrated that microglia are closely related to SAE occurrence and development, and concomitant cognitive impairment. Finally, some potential therapeutic approaches that can prime microglia and neuroinflammation toward the beneficial restorative microglial phenotype in SAE were outlined.

Decoding molecular signature on heart of septic mice with distinct left ventricular ejection fraction.

Dysregulated cardiac function after sepsis in intensive care unit is known to predict poor long-term outcome and increase mortality. Their pathological feature and molecular mechanism remain unclear. We observed that septic patients with depressed left ventricular ejection fraction (LVEF) have the highest in-hospital and 28 days mortality comparing to patients with hyperdynamic LVEF or with heart failure with preserved LVEF. Echocardiograms reveal that survivors post cecum ligation and puncture (CLP) on rodents have stable LVEF and non-survivors have fluctuated LVEF at CLP early phase. CLP-induced mice fall into three groups based on LVEF 24 h post-surgery: high-, low-, and normal-LVEF. Transcriptomic and proteomic analyses identify jointly and distinctively changed genes, proteins and biologically essential pathways in left ventricles from three CLP groups. Notably, transmission electron microscopy shows different mitochondrial and sarcomere defects associated with LVEF variances. Together, this study systematically characterizes the molecular, morphological, and functional alterations in CLP-induced cardiac injury.

Atomic-Scale Characterization of Slip Deformation and Nanometric Machinability of Single-Crystal 6H-SiC.

As an important third-generation semiconductor material, the micro-deformation and removal mechanism of 6H-SiC at the atomic scale are vital for obtaining ultra-smooth and damage-free surface with atomic steps. Due to the difficulties in directly observing the surface/subsurface of nanomachining region by current experimental means, molecular dynamics method is used to study the atomic-scale details in nanomachining process, such as dislocation slip motion, phase transition, and material separation mechanism. The influence of crystallography-induced anisotropy on the slip deformation and nanometric machinability of 6H-SiC is emphatically investigated. This study contributes significantly to the understanding of micro-deformation and nanomachining process of 6H-SiC.

[Value of patient education in the treatment of allergic rhinitis].

OBJECTIVE: To evaluate the effect of patient education on patients with allergic rhinitis (AR). METHOD: From January 2009 to December 2013, 100 cases of allergic rhinitis were treated. The patients were randomly divided into experimental group or control group by Stochastic tables law,50 patients in control group accepted only drug treatment, 50 patients in experimental group accepted both drug treatment and patient education. The difference in compliance with treatment, treatment effect, incidence of adverse drug reactions and complications, average costs and times of treatment between two groups were evaluated by the rhinoconjunctivitis quality of life questionnaire (RQLQ) score. The independent sample t-test and χ2 test were used for statistical analysis. RESULT: The patients of experimental group showed more positive attitude to treatment compared to the patients of control group (P < 0.01). The average scores of each classification and overall symptoms after treatment in experimental group were lower than those in control group (P < 0.05). The incidence of adverse drug reactions (nose-bleed, dry nose,nasal mucosa ulcer)and complications in patients with AR (asthma, chronic cough, secretory otitis media) in experimental group was lower than that in control group, with statistically differences (P < 0.05). The average times of treatment and costs of diagnosis and treatment(calculation of budesonide nasal spray)in experimental group were significantly lower than those in control group (P < 0.01). The total score for RQLQ and the scores of seven dimensions in experimental group were lower than those in control group (P < 0.05). CONCLUSIONS: Patient education can help the patients with AR to cooperate actively with treatment, to reduce the incidence of adverse drug reactions and AR complications, and to save medical costs and improve the quality of life.