Novel measurement system for respiratory aerosols and droplets in indoor environments

The SARS-CoV-2 pandemic has created a great demand for a better understanding of the spread of viruses in indoor environments. A novel measurement system consisting of one portable aerosol-emitting mannequin (emitter) and a number of portable aerosol-absorbing mannequins (recipients) was developed that can measure the spread of aerosols and droplets that potentially contain infectious viruses. The emission of the virus from a human is simulated by using tracer particles solved in water. The recipients inhale the aerosols and droplets and quantify the level of solved tracer particles in their artificial lungs simultaneously over time. The mobile system can be arranged in a large variety of spreading scenarios in indoor environments and allows for quantification of the infection probability due to airborne virus spreading. This study shows the accuracy of the new measurement system and its ability to compare aerosol reduction measures such as regular ventilation or the use of a room air purifier.     

Comparative techno-economic assessment of a large-scale hydrogen transport via liquid transport media

A large-scale point to point hydrogen transport is one strategy for a prospective energy import scenario for certain countries. The case for a hydrogen transport from Australia to Japan has been addressed in several studies. However, most studies lack transparency and detailed insights into the made assumptions thus a fair evaluation of different transport pathways is challenging. To address this issue, we developed a model where a large-scale point to point hydrogen transport of liquid hydrogen is compared with the transport via liquid organic hydrogen carrier (LOHC), namely via methyl cyclohexane and hydrogenated dibenzyl toluene. We analyzed, where energy is required along the different pathways, where hydrogen losses do occur and how the costs are put together. Furthermore, the influence of hydrogen feed costs is also considered. For hydrogen production costs of 5 €₂₀₁₈/kg_H2 the total delivery costs are in the range of 6.40– 8.10 €₂₀₁₈/kg_H2.     

Compound formation in the mercury-cadmium-tellurium-oxygen system

We report on compound formation in the system HgCdTeO. Samples were prepared by solid state reaction of mixtures of the binary oxide components. Specific phases were identified and characterized by X-ray and microprobe techniques. For some of these compounds small single crystals could be prepared and structural data of which are reported. Three groups of phases could be distinguished, most of them being of low symmetry, with Te in +4, +6, and in mixed oxidation states. The monotellurites HgTeO₃ and CdTeO₃ are structurally different and exhibit a large miscibility gap, whereas for the di-tellurites complete solid solution between CdTe₂O₅ and HgTe₂O₅ was found. As to the tellurates, phases with the compositions MTeO₄ and M₃Te₂O₉ (M = Hg, Cd) have been prepared. The Cd₃Te₂O₉-structure is stabilized by 30 mole% Hg. Another tellurate, monoclinic Hg₂TeO₄, was found to be isomorphous to the respective selenate and sulfate and is identical with the mineral magnolite. The interaction of Te₂O₅ with the metal oxides led to the formation of mixed valence compounds with both Te(+4) and Te(+6) of the types M₂Te₂O₇ and MTe₂O₆.     

Investigation of the Possibility of Using UNK Superconducting Dipole Magnets for Producing Rapid-Cycling Magnetic Fields

The superconducting dipoles developed as part of the UNK project have reached a magnetic field 6 T at a rate of up to 0.8 T/sec. Experimental data are presented on the conditioning, rate dependences, and dynamic losses for magnets with two types of superconducting cable (zebra and oxide). Possible ways to decrease the heat release in a dipole operating in rapid-cycling magnetic fields are examined. The results of an analysis of heat release and temperature conditions are presented for a dipole with a winding made of improved current-carrying components.     

Postural and symptomatic improvement after physiotherapy in patients with dizziness of suspected cervical origin

OBJECTIVE: To assess postural performance in patients with dizziness of suspected cervical origin in whom extracervical causes had been excluded, and to assess the effects of physiotherapy on postural performance and subjective complaints of neck pain and dizziness. DESIGN: Prospective, randomized, controlled trial. SETTING: Primary care centers and a tertiary referral center. PATIENTS AND SUBJECTS: Of 65 referrals, 43 patients were excluded because extracervical etiology was suspected. Of the remaining 22 patients, 17 completed the study (15 women, 2 men, x age 37 yr, range 26-49). The controls were 17 healthy subjects (15 women, 2 men, x age 36 yr, range 25-55). INTERVENTION: Physiotherapy based on analysis of symptoms and findings, and aimed to reduce cervical discomfort. Patients were randomized either to receive immediate physiotherapy (n = 9), or to wait 2 months, undergo repeat measurements, and then receive physiotherapy (n = 8). MAIN OUTCOME MEASURES: Posturography, measuring velocity and variance of vibration-induced body sway and variance of galvanically induced body sway. Subjective intensity of neck pain (Visual Analog Scale ratings, 0-100), intensity and frequency of dizziness (subjective score 0-4). RESULTS: The patients manifested significantly poorer postural performance than did healthy subjects (.05 > p > .0001). Physiotherapy significantly reduced neck pain and intensity and the frequency of dizziness (p < .01), and significantly improved postural performance (.05 > p > .0007). CONCLUSIONS: Patients with dizziness of suspected cervical origin are characterized by impaired postural performance. Physiotherapy reduces neck pain and dizziness and improves postural performance. Neck disorders should be considered when assessing patients complaining of dizziness, but alternative diagnoses are common.     

Pneumatic dispensing of nano- to picoliter droplets of liquid metal with the StarJet method for rapid prototyping of metal microstructures

This study presents a new, simple and robust, pneumatically actuated method for the generation of liquid metal micro droplets in the nano- to picoliter range. The so-called StarJet dispenser utilizes a star-shaped nozzle geometry that stabilizes liquid plugs in its center by means of capillary forces. Single droplets of the liquid metal can be pneumatically generated by the interaction of the sheathing gas flow in the outer grooves of the nozzle and the liquid metal. For experimental validation, a print head was build consisting of silicon chips with a star-shaped nozzle geometry and a heated actuator (up to 280°C). The silicon chips are fabricated by Deep Reactive Ion Etching (DRIE). Chip designs with different star-shaped geometries were able to generate droplets with diameters in the range of the corresponding nozzle diameters. The StarJet can be operated in two modes: Either continuous droplet dispensing mode or drop on demand (DoD) mode. The continuous droplet generation mode for a nozzle with 183?μm diameter shows tear-off frequencies between 25 and 120?Hz, while droplet diameters remain constant at 210?μm for each pressure level. Metal columns were printed with a thickness of 0.5–1.0?mm and 30?mm height (aspect ratio >30), to demonstrate the directional stability of droplet ejection and its potential as a suitable tool for direct prototyping of the metal microstructures.     

Simultaneous hydrolysis and fermentation of pulp mill primary clarifier sludge

Bioconversion of sludge from the primary clarifier of a sulphite pulping operation to ethanol offers a number of advantages over conventional disposal options. The amount of material which must be disposed of is reduced while, at the same time, salable and environmentally friendly fuel-ethanol is produced. In this study, primary clarifier sludge (PCS) was shown to be hydrolysed to produce fermentable sugars at a rate proportional to enzyme loading. Initial (1 hour) hydrolysis rates as high as 12.6 g reducing sugar/L · h were observed at an initial enzyme loading of 10 filter paper units (FPU)/g. Hydrolysis was inhibited by spent sulphite liquor (SSL), an inhibition which could be completely overcome by fermenting the SSL to remove sugars. Surfactants were found to only marginally improve the production of sugars. To reduce the deleterious effects of end product inhibition, single stage simultaneous hydrolysis and fermentation (SHF) was carried out using cellulase enzymes and Saccharomyces cerevisiae.