Thermal particle base methods in fluid flow and heat transfer

Journal of Thermal Analysis and Calorimetry -     

An efficient,rapid and facile procedure for conversion of aldoximes to nitriles using triphenylphosphine and N-halo sulfonamides

N,N,N＇,N＇-Tetrabromobenzene-1,3-disulfonamide （TBBDA）/triphenylphosphine and N,N,N＇,N＇-tetra- chlorobenzene-1,3-disulfonamide （TCBDA）/triphenylphosphine have been introduced as highly efficient systems for the versatile conversion of aldoxime derivatives into nitriles. The process reported here is operationally simple and reactions have been mildly performed in dichloromethane at room temperature.     

Gut microbiota, diet, and heart disease

Modulation of the gut microbiota is an area of growing interest, particularly for its link to improving and maintaining the systemic health of the host. It has been suggested to have potential to reduce risk factors associated with chronic diseases, such as elevated cholesterol levels in coronary heart disease (CHD). Diets of our evolutionary ancestors were largely based on plant foods, high in dietary fiber and fermentable substrate, and our gut microbiota has evolved against a background of such diets. Therapeutic diets that mimic plant-based diets from the early phases of human evolution may result in drug-like cholesterol reductions. In contrast, typical Western diets low in dietary fiber and fermentable substrate, and high in saturated and trans fatty acids, are likely contributors to the increased need for pharmacological agents for cholesterol reduction. The gut microbiota of those consuming a Western diet are likely underutilized and depleted of metabolic fuels, resulting in a less than optimal gut microbial profile. As a result, this diet is mismatched to our archaic gut microbiota and, therefore, to our genome, which has changed relatively little since humans first appeared. While the exact mechanism by which the gut microbiota may modulate cholesterol levels still remains uncertain, end products of bacterial fermentation, particularly the short chain fatty acids (i.e., propionate), have been suggested as potential candidates. While more research is required to clarify the potential link between gut microbiota and CHD risk reduction, consuming a therapeutic diet rich in plant foods, dietary fiber, and fermentable substrate would be a useful strategy for improving systemic health, possibly by altering the gut microbiota.     

Wound healing improvement by curcumin‐loaded electrospun nanofibers and BFP‐MSCs as a bioactive dressing

Wound healing, one of the most complex processes of the body involving the cooperation of several important biomolecules and pathways, is one of the major therapeutic and economic issues in regenerative medicine. The present study aimed to introduce a novel electrospun curcumin (Cur)‐incorporated chitosan/polyvinyl alcohol/carbopol/polycaprolactone nanofibrous composite for concurrent delivery of the buccal fat pad‐derived mesenchymal stem cells (BFP‐MSCs) and Cur to a full‐thickness wound on the mouse model. Scaffolds were characterized structurally using scanning electron microscopy (SEM), fluorescence microscopy imaging and Fourier‐transform infrared spectroscopy, and toxicity of the scaffolds was also evaluated after BFP‐MSC seeding by SEM imaging and 3‐(4,5 dimethyiazol‐2‐1)‐2‐5‐diphenyl tetrazolium bromide (MTT) assay. Then, its influence on the wound‐healing process was investigated as a wound dressing for a full‐thickness skin defect in mouse model. Results demonstrated that the designed composite scaffolds have the capability for cell seeding and support their growth and proliferation. Macroscopic and histopathological characteristics were evaluated at the end of the 7 and 14 days after surgery, and their results showed that our designed scaffold groups accelerated the wound‐healing process compared with the control group. Among those, scaffold/Cur, scaffold/Cur/BFP‐MSC and scaffold/BFP‐MSC groups demonstrated more wound repair efficacy. These results indicated that the combined grafts can be used to improve the wound‐healing process, and therefore, the electrospun nanofibers presented in this study, Cur and BFP‐MSC together, were demonstrated to have promising potential for wound‐dressing applications.     

Tribromoisocyanuric Acid (TBCA) and Oxone®‐MX Systems as Oxidizing Agents: Oxidative Coupling of Thiols to Their Corresponding Disulfides under Mild and Heterogeneous Conditions

Tribromoisocyanuric acid (TBCA) and Oxone^®‐MX systems were used as effective oxidizing agents for the oxidation of thiols to their corresponding disulfides under mild conditions at room temperature with good to excellent yields.     

Selective and efficient oxidation of sulfides to sulfoxides using ammonium cerium (IV) nitrate in the presence of a catalytic amount of KBr or NaBr

A wide range of aliphatic or aromatic sulfides are selectively oxidized to the corresponding sulfoxides using ammonium cerium (IV) nitrate (CAN) and a catalytic amount of KBr or NaBr in the presence of wet SiO₂ in CH₂Cl₂ under heterogeneous conditions in moderate to high yields.     

Three component reactions：An efficient and green synthesis of 3, 4-dihydropyrimidin-2-(1H)-ones and thiones using silica gel-supported L-pyrrolidine-2-carboxylic acid-4-hydrogen sulfate

An environmentally benign aqueous protocol for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones and thiones promoted by a green catalyst,silica gel-supported L-pyrrolidine-2-carboxylic acid-4-hydrogen sulfate,has been developed.The use of nontoxic,thermally stable and inexpensive amino acid catalyst makes the process simple with minimal amount of chemical waste.Compared with classical Biginelli reaction conditions,this new method has the advantages of high yields and simple workup procedures.     

Optimal free-defect synthesis of four-bar linkage with joint clearance using PSO algorithm

This paper presents the design of planar four-bar linkages free of order, branch and circuit defects, for the purpose of path generation, having clearances at one, two, three or all of its joints. Joint clearance is treated as a massless virtual link and its direction is known by the direction of the joint force. A Particle Swarm Optimization based algorithm is given here to solve this highly nonlinear optimization problem with some constraints, namely; the Grashof’s and free of the foregoing defects conditions. An example is included in which the optimal problem is solved for different cases; namely planar four-bar linkage having clearances at one, two, three, all of the joints and without clearance. For all the designs, the generated paths, the errors and the directions of the virtual links are plotted and are compared. Finally, we compare the optimal designs with reality.     

Optimization of the reflux ratio for methanol–water stage distillation column

In this paper, the enthalpy-concentration method was applied in order to model a steady-state continuous methanol–water mixture distillation column. This work includes three steps; first, to develop a code in MATLAB v.7.6 to apply to the mathematical model of the column. The second step is to simulate the column using HYSIS v.3.2. While the third is the calculation of the optimized reflux ratio to minimize the operating cost. For a distillation tower such as the methanol–water splitter in this study, there are relatively few degrees of freedom that can be manipulated in order to minimize operating costs; the reflux ratio can influence the steady-state operating point and therefore the daily costs. In this paper, we have discussed the trade-offs between reflux ratios and operating costs. A correlation is derived to define the optimum value of the reflux ratio as an exponential function of a certain economic parameter of energy prices and depreciation costs. We demonstrate that, at low energy prices or high equipment depreciation costs, the optimum reflux factor is high.