Noninvasive characterization methods for ultra-short laser pulse induced volume modifications.

We present two noninvasive characterization methods to investigate laser induced modifications in bulk fused silica glasses. The methods discussed are immersion microscopy and scanning acoustic microscopy (SAM). SAM shows merits in measuring the distance from sample surface to the first detectable density change of the modification, while immersion microscopy offers a look into the modification. Both noninvasive methods are preferred over conventional polishing or etching techniques due to the facts, that multiple investigations can be done with only one sample and lower time expenditure. The type II modifications were introduced by focusing laser pulses with high repetition rates into the fused silica.

Role of Doping Agent Degree of Sulfonation and Casting Solvent on the Electrical Conductivity and Morphology of PEDOT:SPAES Thin Films.

Poly(3,4-ethylenedioxythiophene) (PEDOT) plays a key role in the field of electrically conducting materials, despite its poor solubility and processability. Various molecules and polymers carrying sulfonic groups can be used to enhance PEDOT's electrical conductivity. Among all, sulfonated polyarylether sulfone (SPAES), prepared via homogenous synthesis with controlled degree of sulfonation (DS), is a very promising PEDOT doping agent. In this work, PEDOT was synthesized via high-concentration solvent-based emulsion polymerization using 1% w/w of SPAES with different DS as dopant. It was found that the PEDOT:SPAESs obtained have improved solubility in the chosen reaction solvents, i.e., N, N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone and, for the first time, the role of doping agent, DS and polymerization solvents were investigated analyzing the electrical properties of SPAESs and PEDOT:SPAES samples and studying the different morphology of PEDOT-based thin films. High DS of SPAES, i.e., 2.4 meq R-SO3-× g-1 of polymer, proved crucial in enhancing PEDOT's electrical conductivity. Furthermore, the DMSO capability to favor PEDOT and SPAES chains rearrangement and interaction results in the formation of a polymer film with more homogenous morphology and higher conductivity than the ones prepared from DMAc, DMF, and NMP.

Geometry Optimization of Thermoelectric Modules: Deviation of Optimum Power Output and Conversion Efficiency.

Besides the material research in the field of thermoelectrics, the way from a material to a functional thermoelectric (TE) module comes alongside additional challenges. Thus, comprehension and optimization of the properties and the design of a TE module are important tasks. In this work, different geometry optimization strategies to reach maximum power output or maximum conversion efficiency are applied and the resulting performances of various modules and respective materials are analyzed. A Bi2Te3-based module, a half-Heusler-based module, and an oxide-based module are characterized via FEM simulations. By this, a deviation of optimum power output and optimum conversion efficiency in dependence of the diversity of thermoelectric materials is found. Additionally, for all modules, the respective fluxes of entropy and charge as well as the corresponding fluxes of thermal and electrical energy within the thermolegs are shown. The full understanding and enhancement of the performance of a TE module may be further improved.

Risking health for rental housing: Reviewing service access in the informal backyard rental sector.

Informal backyard rentals (IBRs) constitute South Africa's fastest growing housing subsector, flourishing within a relative research vacuum and without national policy intervention to address the vulnerabilities of stakeholders to the health risks potentially presented. This article reviewed the literature on IBRs, focussing on past policies and interventions, general characteristics, infrastructure and service access to inform an analysis of potential health risks from the existing literature to guide future research and policy-making. Research followed a qualitative approach to review IBR literature dating after 2004. Relevant publications were identified from bibliographic databases using Boolean search logic and by reviewing citations in and later citations of these publications. Relevant secondary sources were also included. The review evidenced that IBRs have received increasing policy, but limited research attention, and that health hazards have been particularly neglected. Although issues such as shared water and sanitation, inappropriate waste disposal, poor hygiene practices, high densities and poor quality structures have been referenced extensively - alluding to risks and health concerns - few studies have focussed directly on health, risk and vulnerability. The risk analysis completed based on the literature made potential risks explicit, exemplified by references to specific conditions, such as HIV/AIDS, tuberculosis and the coronavirus pandemic, demonstrating pathogenic pathways, contamination and transmission risks conducive to poor health, infection and potential disaster. The review captured and updated the contemporary literature on IBRs, with the subsequent analysis providing a platform for future empirical research on health, infrastructure and IBRs to address potential risks towards positive change in future policies.

Transducer characterization by sound field measurements.

The paper discusses different methods for characterizing an ultrasonic transducer by sound field measurements and introduces a novel easy-to-implement method besides the commonly known point reflector and hydrophone measurement methods. The characterization methods that are presented are particularly suited to measuring the actual transducer element size and determining fabrication details and asymmetries, where the necessary information is derived from the position of the ultrasonic focus and the structure of the sound field. The procedure is discussed on the basis of the following practical problems: measurement of the acoustically relevant element size of a planar 3-MHz annular array made of lead zirconate titanate (PZT) using a single point reflector; visualization of inaccuracies, asymmetries, and fabrication details for different setups with transducer frequencies between 3 and 50 MHz; determination of the element sizes of the single elements of a spherically curved 9-MHz sparse annular array and examination of the transducer¿s focusing characteristics in a fluid containing scattering particles; and determination of the focus position of a 9-MHz single-element transducer with acoustic lens and comparison between two lens materials.