A regularised boundary element formulation for contactless SAR evaluations within homogeneous and inhomogeneous head phantoms

This work presents a Boundary Element Method (BEM) formulation for contactless electromagnetic field assessments. The new scheme is based on a regularised BEM approach that requires the use of electric measurements only. The regularisation is obtained by leveraging on an extension of Calderón techniques to rectangular systems leading to well-conditioned problems independent of the discretisation density. This enables the use of highly discretized Huygens surfaces that can be consequently placed very near to the radiating source. In addition, the new regularised scheme is hybridised with both surfacic homogeneous and volumetric inhomogeneous forward BEM solvers accelerated with fast matrix–vector multiplication schemes. This allows for rapid and effective dosimetric assessments and permits the use of inhomogeneous and realistic head phantoms. Numerical results corroborate the theory and confirms the practical effectiveness of all newly proposed formulations.     

Determination of human muscle protein fractional synthesis rate: an evaluation of different mass spectrometry techniques and considerations for tracer choice

In the present study, different MS methods for the determination of human muscle protein fractional synthesis rate (FSR) using [ring‐¹³C₆]phenylalanine as a tracer were evaluated. Because the turnover rate of human skeletal muscle is slow, only minute quantities of the stable isotopically labeled amino acid will be incorporated within the few hours of a typical laboratory experiment. GC combustion isotope ratio MS (GC‐C‐IRMS) has thus far been considered the ‘gold’ standard for the precise measurements of these low enrichment levels. However, advances in liquid chromatography‐tandem MS (LC‐MS/MS) and GC‐tandem MS (GC‐MS/MS) have made these techniques an option for human muscle FSR measurements. Human muscle biopsies were freeze dried, cleaned, and hydrolyzed, and the amino acids derivatized using either N‐acetyl‐n‐propyl, phenylisothiocyanate, or N‐methyl‐N‐(tert‐butyldimethylsilyl)trifluoroacetamide (MTBSTFA) for GC‐C‐IRMS, LC‐MS/MS, and GC‐MS/MS analysis, respectively. A second derivative, heptafluorobutyric acid (HFBA), was also used for GC‐MS/MS analysis as an alternative for MTBSTFA. The machine reproducibility or the coefficients of variation for delta tracer‐tracee‐ratio measurements (delta tracer‐tracee‐ratio values around 0.0002) were 2.6%, 4.1%, and 10.9% for GC‐C‐IRMS, LC‐MS/MS, and GC‐MS/MS (MTBSTFA), respectively. FSR determined with LC‐MS/MS compared well with GC‐C‐IRMS and so did the GC‐MS/MS when using the HFBA derivative (linear fit Y = 1.08 ± 0.10, X + 0.0049 ± 0.0061, r = 0.89 ± 0.01, P < 0.0001). In conclusion, (1) IRMS still offers the most precise measurement of human muscle FSR, (2) LC‐MS/MS comes quite close and is a good alternative when tissue quantities are too small for GC‐C‐IRMS, and (3) If GC‐MS/MS is to be used, then the HFBA derivative should be used instead of MTBSTFA, which gave unacceptably high variability. Copyright © 2014 John Wiley & Sons, Ltd.     

Preparation and Characterization of Protonated Fumaric Acid

Fumaric acid was reacted with the binary superacidic systems HF/SbF₅ and HF/AsF₅. The O,O'-diprotonated [C₄H₆O₄]²⁺([MF₆]^–)₂ (M = As, Sb) and the O-monoprotonated [C₄H₅O₄]⁺[MF₆]^– (M = As, Sb) species are formed depending on the stoichiometric ratio of the Lewis acid to fumaric acid. The colorless salts were characterized by low-temperature vibrational spectroscopy. In case of the hexafluoridoantimonates single-crystal X-ray structure analyses were carried out. The [C₄H₆O₄]²⁺([SbF₆]^–)₂ crystallizes in the monoclinic space group C2/c with four formula units per unit cell and [C₄H₅O₄]⁺[SbF₆]^– crystallizes in the triclinic space group P1 with one formula unit per unit cell. The protonation of fumaric acid does not cause a notable change of the C=C bond length. The experimental data are discussed together with quantum chemical calculations of the cations [C₄H₆O₄ · 4 HF]²⁺ and [C₄H₆O₄ · 2 H₂CO · 2 HF]²⁺.     

Investigation of dense slurry suspensions with coaxial mixers: Influences of design variables through tomography and mathematical modelling

The coaxial mixers enhance the suspension of concentrated slurries in an agitated reactor. In this research work, the complex slurry suspension and dissemination behavior in a coaxial slurry mixing system (comprised of a close clearance anchor rotating with a low speed and an inner axial impeller rotating with a high speed) was analyzed employing ERT (electrical resistance tomography, a non-intrusive flow visualization technique), and computational fluid dynamics (CFD). The numerical models were validated by comparing the axial solid concentration profiles generated using the ERT data and the CFD simulation results. The influences of various important parameters such as the diameter of the inner axial impeller, the inner impeller type, and the inner impeller spacing on the hydrodynamic characteristics of the slurry suspensions in a coaxial mixing vessel were thoroughly analyzed. The radial and axial velocity profiles of solid particles were generated using the validated mathematical models. The assessment of energy loss due to the solid–solid collisions, the particle–fluid frictions, and the particle–vessel wall collisions was conducted. The evaluation of optimum inner impeller clearance and inner impeller diameter is essential to attain a high degree of solids suspension and dissemination in a coaxial slurry mixing system.     

光束质量对闪烁和流速测量的影响分析

给出了用发光二极管测量闪烁和流速光源远场理想特性的表达式.波前扭曲可以分解成波前倾斜和曲率改变两部分来处理.波前倾斜和离轴接收信号的情况相当,对测量结果影响不大.当波前曲率半径不等于到光源的距离时,对流速和闪烁强度测量都会带来不能忽略的误差,路径加权函数的对称特性也会改变.最后给出的流速测量的实验结果和理论计算是一致的.     

State-crossing from a Locally Excited to an Electron Transfer State(SLEET) Model Rationalizing the Aggregation-induced Emission Mechanism of (Bi)piperidylanthracenes

Luminogens with aggregation-induced emission(AIE)characteristics(or AIEgens)have been widely used in various applications due to their excellent luminescent properties in molecular aggregates and the solid state.A deep understanding of the AIE mechanism is critical for the rational development of AIEgens.In this work,the“state-crossing from a locally excited to an electron transfer state”(SLEET)model is employed to rationalize the AIE phenomenon of two(bi)piperidylanthracenes.According to the SLEET model,an electron transfer(ET)state is formed along with the rotation of the piperidyl group in the excited state of(bi)piperidylan-thracene monomers,leading to fluorescence quenching.In contrast,a bright state exists in the crystal and molecular aggregates of these compounds,as the intermolecular interactions restrict the formation of the dark ET state.This mechanistic understanding could inspire the deployment of the SLEET model in the rational designs of various functional AIEgens.     

Antibacterial Activity of Pharmaceutical-Grade Rose Bengal: An Application of a Synthetic Dye in Antibacterial Therapies

Rose bengal has been used in the diagnosis of ophthalmic disorders and liver function, and has been studied for the treatment of solid tumor cancers. To date, the antibacterial activity of rose bengal has been sporadically reported; however, these data have been generated with a commercial grade of rose bengal, which contains major uncontrolled impurities generated by the manufacturing process (80–95% dye content). A high-purity form of rose bengal formulation (HP-RBf, >99.5% dye content) kills a battery of Gram-positive bacteria, including drug-resistant strains at low concentrations (0.01–3.13 μg/mL) under fluorescent, LED, and natural light in a few minutes. Significantly, HP-RBf effectively eradicates Gram-positive bacterial biofilms. The frequency that Gram-positive bacteria spontaneously developed resistance to HP-RB is extremely low (less than 1 × 10⁻¹³). Toxicity data obtained through our research programs indicate that HP-RB is feasible as an anti-infective drug for the treatment of skin and soft tissue infections (SSTIs) involving multidrug-resistant (MDR) microbial invasion of the skin, and for eradicating biofilms. This article summarizes the antibacterial activity of pharmaceutical-grade rose bengal, HP-RB, against Gram-positive bacteria, its cytotoxicity against skin cells under illumination conditions, and mechanistic insights into rose bengal’s bactericidal activity under dark conditions.     

Immunity in the ABM-DSGE Framework for Preventing and Controlling Epidemics—Validation of Results

The COVID-19 pandemic has raised many questions on how to manage an epidemiological and economic crisis around the world. Since the beginning of the COVID-19 pandemic, scientists and policy makers have been asking how effective lockdowns are in preventing and controlling the spread of the virus. In the absence of vaccines, the regulators lacked any plausible alternatives. Nevertheless, after the introduction of vaccinations, to what extent the conclusions of these analyses are still valid should be considered. In this paper, we present a study on the effect of vaccinations within the dynamic stochastic general equilibrium model with an agent-based epidemic component. Thus, we validated the results regarding the need to use lockdowns as an efficient tool for preventing and controlling epidemics that were obtained in November 2020.     

喷流冷却复合陶瓷薄片激光器的热特性仿真分析及实验研究

为分析喷流冷却复合陶瓷薄片激光器的热特性,设计用于冷却复合陶瓷薄片的喷流冷却系统.利用湍流换热理论和计算流体动力学仿真方法建立喷流冷却复合陶瓷薄片激光器的流固耦合热仿真模型,定义评价其冷却能力和冷却均匀性的定量参数.根据该仿真模型得到喷流冷却系统的最优设计参数,并进行实验验证.使用163孔喷板,流量为0.2kg/s,入口温度为20℃,在1200 W泵浦时获得359 W激光输出功率,并测得复合陶瓷薄片上表面的最高温度为92℃.激光输出功率与复合陶瓷薄片上表面温度均与泵浦功率呈近似正线性关系,且温度的实验值与仿真值相符度较高.     

Sonoelectrochemical hydrogenation of safrole: A reactor design,statistical analysis and computational fluid dynamic approach

In this work, ultrasound-assisted electrocatalytic hydrogenation (US-ECHSA) of safrole was carried out in water medium, using sacrificial anode of nickel. The ultrasonic irradiation was carried out at frequency of 20 kHz ± 500 Hz with a titanium cylindrical horn (MS 73 microtip; Ti-6AI-4V alloy; 3.0 mm diameter). The optimal conditions were analyzed by statistical experimental design (fractional factorial). The influence of the sonoelectrochemical reactor design was also investigated by using computational fluid dynamics as simulation tool. Among the five parameters studied: catalyst type, use of β-cyclodextrin as inverse phase transfer catalyst, sonoelectrochemical reactor design, ultrasound mode and the temperature of the solution, only the last three were significant. The hydrogenation product, dihydrosafrole, reached 94% yield, depending on the experimental conditions applied. Data of computational fluid dynamics showed that a wing shape tube added to the sonoelectrochemical reactor can work as a cooling apparatus, during the electrochemical process. The reactional solution temperature diminishes 14 °C when compared to the four-way-type reactor. Cooper cathode, absence of β-cyclodextrin, four-way-type reactor, ultrasound continuous mode (14 W) and absence of temperature control were the most effective reaction parameters for the safrole hydrogenation using US-ECHSA method. The proposed approach represents an important contribution for understanding the hydrodynamic behavior of sonoelectrochemical reactors designs and, consequently, for the reducing of the experimental costs inherent to the sonoelectrochemical process.