Thermodynamic and kinetic examinations of inorganic materials formation

Inorganic materials formation is the result of a complicated interplay between thermodynamics and kinetics. Improved understanding of such factors can aid the synthesis of target materials and the discovery of new materials. Here, techniques for carrying out time-resolved studies were developed and demonstrated for the investigation of solvothermal and solid state reactions. Detailed kinetic reaction progress maps were constructed, showing quantitative information on the kinetic development of the quantity of each constituent phase during chemical reactions. The approach deployed has little restriction on the reaction conditions, and therefore can be used as a protocol for other kinetic studies of the demonstrated reaction types: solvothermal and solid state. It is shown that detailed and thorough reaction kinetics can be retrieved reliably by combining X-ray diffraction (XRD) with supplementary characterization methods without reliance on synchrotron-based facilities, allowing for high-throughout screening of different reactions. Synchrotron-based in situ XRD was also tested and developed, which can provide more insight for those selected systems that require higher- fidelity data collection. In this dissertation, it is shown that valuable mechanistic knowledge on materials syntheses can be learned from such types of thermodynamic and kinetic investigations, which can be effectively employed for the discovery of new material structures. Comprehensive quantitative information was obtained on phase evolution during the solvothermal synthesis of Cu4O3 based on time-resolved ex situ investigations. Combined with the observation of phase correlations, it was realized that the transition through Cu2(NO3)(OH)3 and a proper redox environment is critical to form Cu4O3. With the use of in situ energy-dispersive X-ray diffraction carried out at 6-BM-B in Advanced Photon Source, it was verified that all copper oxide forms CuO, Cu2O, and Cu4O3 were made at the solvothermal temperature. It was also shown that at the local scale, no apparent transformation between Cu4O3 and CuO / Cu2O took place, but the transformation between CuO and Cu2O was evident, supporting the reaction mechanism proposed from the ex situ study. Through changes in the solvothermal chemistry, it was shown that direct transformation of Cu2(NO3)(OH)3 to Cu4O3 could not be achieved with a simple mixture of ethanol and dimethylformamide. Some species generated in the original Cu4O3 synthesis scheme are required in order for such transformation to take place, which are yet to be confirmed in identity. After testing with several solvothermal solvents, it was discovered that solvent chemistry has a huge impact on the phase stability of Cu-containing inorganic materials, and four new crystalline phases were suggested based on unmatched diffraction patterns. Among these new structures, one is a coordination compound, which possesses a unique coordination stereochemistry. In this structure, Cu is coordinated to two chelating ethylenediamine ligands and one monodentate ethylenediamine ligand, which is unprecedented. Solid state synthesis of Fe2SiS4 was investigated using in situ X-ray diffraction. Important factors that affect Fe2SiS4 formation kinetics are identified to be a peritectic transition, intermetallic formation, and particle size reduction. These factors were explored for the discovery of new ternary chalcogenide materials. Realizing the effectiveness of burst formation of superheated liquid on materials formation kinetics, we explored flux-crystallization of Ba-Fe-S materials utilizing BaS3 as a reactive flux. Both lab and synchrotron in situ X-ray diffraction verified that novel crystalline phases formed when the system was in the flux state. Through the analysis of a particular set of synchrotron in situ X-ray diffraction patterns, we give suggestions on the diffraction profiles of five new flux-grown Ba-Fe-S phases. Materials discovery was also carried out with solid state synthesis for ternary sulfide and selenides systems with the help of ball milling reagents for kinetic enhancement. Based on the X-ray diffraction results of the products, the existence of three new materials are shown in the ternary systems of Sr-V-S, Sr-Cr-S, and Sr-Ni-S

Understand the role of nanostructure for efficient hydrogen generation on immobilized photocatalysts

For the purpose of efficiently utilizing the renewable solar energy, it is of vital importance to understand the key factors that contribute to the performance merits for photocatalysis applications. The efficiencies toward photocatalytic water splitting were measured on three distinct immobilized titania nanostructures. Different trends in the nanostructure – water splitting efficiency relationship were observed, depending on the specific application mode being either photoelectrochemical cell (PEC) or direct heterogeneous reaction (DHR). Investigations were carried out to elucidate on how PEC and DHR benefit to a varying degree from the hydrothermal processing history, electronic properties, interface structures, and reactive facets of the resultant nanostructures. Good PEC cell performance was identified to be related to topotactically formed samples with intimate-contacting surfaces that eased inter-particle charge transfer. Additional benefit for PEC cell was found to be achieved from the vectorial conduction pathway in pseudo-one dimensional structure. On the other hand, high activity of DHR photocatalysis is attributed mainly to the exposed high reactivity crystal facets. The presence of anatase TiO2 {010} facets was identified to enhance electron-hole separation and create specific surface states that facilitate interactions across the semiconductor/electrolyte interfaces.Bachelor of Engineering (Materials Engineering

Thermodynamic and kinetic examinations of inorganic materials formation

Inorganic materials formation is the result of a complicated interplay between thermodynamics and kinetics. Improved understanding of such factors can aid the synthesis of target materials and the discovery of new materials. Here, techniques for carrying out time-resolved studies were developed and demonstrated for the investigation of solvothermal and solid state reactions. Detailed kinetic reaction progress maps were constructed, showing quantitative information on the kinetic development of the quantity of each constituent phase during chemical reactions. The approach deployed has little restriction on the reaction conditions, and therefore can be used as a protocol for other kinetic studies of the demonstrated reaction types: solvothermal and solid state. It is shown that detailed and thorough reaction kinetics can be retrieved reliably by combining X-ray diffraction (XRD) with supplementary characterization methods without reliance on synchrotron-based facilities, allowing for high-throughout screening of different reactions. Synchrotron-based in situ XRD was also tested and developed, which can provide more insight for those selected systems that require higher- fidelity data collection. In this dissertation, it is shown that valuable mechanistic knowledge on materials syntheses can be learned from such types of thermodynamic and kinetic investigations, which can be effectively employed for the discovery of new material structures. Comprehensive quantitative information was obtained on phase evolution during the solvothermal synthesis of Cu4O3 based on time-resolved ex situ investigations. Combined with the observation of phase correlations, it was realized that the transition through Cu2(NO3)(OH)3 and a proper redox environment is critical to form Cu4O3. With the use of in situ energy-dispersive X-ray diffraction carried out at 6-BM-B in Advanced Photon Source, it was verified that all copper oxide forms CuO, Cu2O, and Cu4O3 were made at the solvothermal temperature. It was also shown that at the local scale, no apparent transformation between Cu4O3 and CuO / Cu2O took place, but the transformation between CuO and Cu2O was evident, supporting the reaction mechanism proposed from the ex situ study. Through changes in the solvothermal chemistry, it was shown that direct transformation of Cu2(NO3)(OH)3 to Cu4O3 could not be achieved with a simple mixture of ethanol and dimethylformamide. Some species generated in the original Cu4O3 synthesis scheme are required in order for such transformation to take place, which are yet to be confirmed in identity. After testing with several solvothermal solvents, it was discovered that solvent chemistry has a huge impact on the phase stability of Cu-containing inorganic materials, and four new crystalline phases were suggested based on unmatched diffraction patterns. Among these new structures, one is a coordination compound, which possesses a unique coordination stereochemistry. In this structure, Cu is coordinated to two chelating ethylenediamine ligands and one monodentate ethylenediamine ligand, which is unprecedented. Solid state synthesis of Fe2SiS4 was investigated using in situ X-ray diffraction. Important factors that affect Fe2SiS4 formation kinetics are identified to be a peritectic transition, intermetallic formation, and particle size reduction. These factors were explored for the discovery of new ternary chalcogenide materials. Realizing the effectiveness of burst formation of superheated liquid on materials formation kinetics, we explored flux-crystallization of Ba-Fe-S materials utilizing BaS3 as a reactive flux. Both lab and synchrotron in situ X-ray diffraction verified that novel crystalline phases formed when the system was in the flux state. Through the analysis of a particular set of synchrotron in situ X-ray diffraction patterns, we give suggestions on the diffraction profiles of five new flux-grown Ba-Fe-S phases. Materials discovery was also carried out with solid state synthesis for ternary sulfide and selenides systems with the help of ball milling reagents for kinetic enhancement. Based on the X-ray diffraction results of the products, the existence of three new materials are shown in the ternary systems of Sr-V-S, Sr-Cr-S, and Sr-Ni-S

Value of cold laser combined with choledochoscopy in treatment of residual stones after biliary surgery

ObjectiveTo investigate the value of cold laser combined with choledochoscopy in the treatment of residual stones after biliary surgery. MethodsA retrospective analysis was performed for the clinical data of 79 patients with residual stones after biliary surgery who were admitted to Fuzhou General Hospital of Nanjing Military Area Command from January 2015 to June 2016. All the patients underwent cold laser combined with choledochoscopy at 6 weeks after surgery. The cure rate and complications were observed. ResultsAll the patients underwent successful lithotripsy, and the cure rate was 100%. Of all the patients, 68 did not experience any postoperative complication, 7 experienced abdominal distension, abdominal pain, and diarrhea, which achieved spontaneous remission after observation, and 4 experienced fear of cold and chill, which were improved after symptomatic treatment. No patients experienced serious complications, such as bile duct injury, biliary tract perforation, bile leakage, and hematobilia. ConclusionCold laser combined with choledochoscopy has a good effect, a high level of safety, and good repeatability in the treatment of residual stones after biliary surgery; therefore, it holds promise for clinical application

MEMS Inertial Sensors Based Gait Analysis for Rehabilitation Assessment via Multi-Sensor Fusion

Gait and posture are regular activities which are fully controlled by the sensorimotor cortex. In this study, fluctuations of joint angle and asymmetry of foot elevation in human walking stride records are analyzed to assess gait in healthy adults and patients affected with gait disorders. This paper aims to build a low-cost, intelligent and lightweight wearable gait analysis platform based on the emerging body sensor networks, which can be used for rehabilitation assessment of patients with gait impairments. A calibration method for accelerometer and magnetometer was proposed to deal with ubiquitous orthoronal error and magnetic disturbance. Proportional integral controller based complementary filter and error correction of gait parameters have been defined with a multi-sensor data fusion algorithm. The purpose of the current work is to investigate the effectiveness of obtained gait data in differentiating healthy subjects and patients with gait impairments. Preliminary clinical gait experiments results showed that the proposed system can be effective in auxiliary diagnosis and rehabilitation plan formulation compared to existing methods, which indicated that the proposed method has great potential as an auxiliary for medical rehabilitation assessment

Mitofusin 2 protects hepatocyte mitochondrial function from damage induced by GCDCA.

Mitochondrial impairment is hypothesized to contribute to the pathogenesis of chronic cholestatic liver diseases. Mitofusin 2 (Mfn2) regulates mitochondrial morphology and signaling and is involved in the development of numerous mitochondrial-related diseases; however, a functional role for Mfn2 in chronic liver cholestasis which is characterized by increased levels of toxic bile acids remain unknown. Therefore, the aims of this study were to evaluate the expression levels of Mfn2 in liver samples from patients with extrahepatic cholestasis and to investigate the role Mfn2 during bile acid induced injury in vitro. Endogenous Mfn2 expression decreased in patients with extrahepatic cholestasis. Glycochenodeoxycholic acid (GCDCA) is the main toxic component of bile acid in patients with extrahepatic cholestasis. In human normal hepatocyte cells (L02), Mfn2 plays an important role in GCDCA-induced mitochondrial damage and changes in mitochondrial morphology. In line with the mitochondrial dysfunction, the expression of Mfn2 decreased significantly under GCDCA treatment conditions. Moreover, the overexpression of Mfn2 effectively attenuated mitochondrial fragmentation and reversed the mitochondrial damage observed in GCDCA-treated L02 cells. Notably, a truncated Mfn2 mutant that lacked the normal C-terminal domain lost the capacity to induce mitochondrial fusion. Increasing the expression of truncated Mfn2 also had a protective effect against the hepatotoxicity of GCDCA. Taken together, these findings indicate that the loss of Mfn2 may play a crucial role the pathogenesis of the liver damage that is observed in patients with extrahepatic cholestasis. The findings also indicate that Mfn2 may directly regulate mitochondrial metabolism independently of its primary fusion function. Therapeutic approaches that target Mfn2 may have protective effects against hepatotoxic of bile acids during cholestasis

Analysis of Design Method and Mechanical Properties of Plug-In Composite Shear Wall

Assembly buildings are an important direction for the future development of the construction field. They can be prefabricated in the factories and then assembled on-site, which significantly improves construction efficiency. The shear walls are the most important lateral force-resisting elements in building structures, and at this stage, there are more and more studies on the prefabricated shear wall. In this paper, a new composite shear wall structure is proposed. The composite shear wall is a part of a prefabricated building, which is prefabricated into a single shear wall unit in the factory. During the construction, the upper and lower prefabricated shear wall units are connected by the plug-in. The design methods of splicing connection are given for the design of this composite shear wall structure. Eleven composite wall models under different parameters are established by using the finite element method, especially the fine modeling of the upper and lower connection parts. Compared with the conventional composite shear wall model of the same dimensions, the mechanical behaviors of the two models are similar. In the simulation of cyclic loading, the new composite shear wall shows good ductility and energy dissipation capacity, and also meets the established requirements of building seismic performance. Therefore, it can be concluded that the new prefabricated composite shear walls have good development prospects and application values

Effect of the overexpression of Mfn2 or the truncated Mfn2 mutant on mitochondrial morphology and mitochondrial function in GCDCA-treated L02 cells.

<p>(A) Western blot analysis was used to detect the expression of Mfn2-GFP and the truncated Mfn2 mutant transfected into L02 cells. (B) Confocal microscope photographs indicated increased mitochondrial localization of Mfn2 and the truncated Mfn2 mutant and their roles in mitochondrial morphology. (C) Proportions of cells with fragmented mitochondrial pattern was determined in at least six different cultures under basal conditions (untreated), and after the L02 cells were treated with various doses (25, 50, 75, or 100 µM) of GCDCA for 6 h. The results are expressed as a percentage of the control value, which was set at 100%. The values are the means ± SEM. *P<0.05 versus the control group, <b>^#</b>P<0.05, <b>^##</b>P<0.01 versus the GCDCA group, n = 6.</p