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.     

Composition and formation of the sleeve enveloping a central venous catheter

PURPOSE: After catheterization, 42% to 100% of central venous catheters are surrounded by a "fibrin sleeve." This sleeve has been considered the cause of catheter-related infections, withdrawal occlusion, and pulmonary embolism. The reactions between the vein wall and the catheter were studied. METHODS: A silicone catheter was placed in the anterior caval vein of 123 rats. After in situ fixation at scheduled intervals, the pathologic changes were studied on semi-serial histologic sections by means of light microscopy, transmission electron microscopy, and scanning electron microscopy (SEM). In 36 rats, the catheter was withdrawn immediately; in 72 rats, it was left in situ up to 6 months; and in 15 rats, the study was performed up to 10 months after withdrawal of a catheter that had remained in situ for 6 months. RESULTS: In the group in which the catheter was withdrawn immediately, mural thrombi disappeared by day 7. In the group in which the catheter remained in situ, thrombi remained around the proximal portion of the catheter. This pericatheter thrombosis (PCT) was invaded by migrating and proliferating smooth muscle cells (SMCs), originating from an injured vein wall, and transformed from day 7 into a tissue composed predominantly of SMCs and collagen and covered by endothelial cells. Later, the number of cells decreased, and the relative amount of collagen increased. Up to 10 months after withdrawal of the catheter, the collapsed sleeve was still present within the vein. CONCLUSION: The sleeve around a central venous catheter is not a fibrin sleeve, but a stable cellular-collagen tissue covered by endothelium. It is mainly formed by smooth muscle cells migrating from the injured vein wall into the early pericatheter thrombus.     

2‐(1‐Ethynylpyrene)‐Adenosine as a Folding Probe for RNA—Pyrene in or out

A series of short RNA duplexes containing one or two 1‐ethynylpyrene‐modified adenine bases was synthesised. The melting behaviour of these duplexes was examined by monitoring temperature‐dependent pyrene fluorescence. In the singly modified RNA duplexes, the bases flanking the ethynylpyrene‐rA were varied to examine the sequence specificity of the fluorescence change of pyrene upon RNA hybridisation. Because an increase in pyrene fluorescence upon melting of the duplex can be correlated with intercalation of pyrene, and a decrease is usually associated with the position of pyrene outside the strand, a relationship between the flanking bases and the tendency of the dye to intercalate has been established. It was found that pyrene intercalation is less likely to take place if the modified base is flanked only by A–U base pairs. Flanking G–C base pairs, even only in the 5′‐direction of the modified base, will favour intercalation. In addition, we examined a doubly modified compound that had a pyrene located on each strand. The spectra indicated that the two pyrenes were close enough for interaction. Upon melting of the strand, a fluorescence blue shift corresponding to the dissociation of the pyrene–pyrene complex could be observed in addition to the intensity effect already known from the singly modified compounds. Two melting curves based on the different properties of the fluorophore could be extracted, leading to different melting points corresponding to the global duplex melting and to the change of local pyrene environment, respectively.     

Dünnschichten als Targets für den Schwerionenstrahl

Thin films targets For the understanding of the interaction between matter and matter ions are accelerated on a fixed target. The targets are self-supporting layers with a thickness between several nanometres up to centimetres. The self-supporting thin films are deposited in high-vacuum evaporation units on a soluble interlayer on a substrate, from which they can be removed. Typical materials are carbon, nearly all the metals, the transition metals and several rare earth materials. Beside the chemical purity fairly often an isotopic purity is required.     

Neuere Untersuchungen über das Korrosionsverhalten und Korrosionsschutzmaßnahmen von Leichtmetall-Legierungen im Schiffbau und ähnlichen Anwendungsgebieten

Recent investigations into the corrosion behaviour and corrosion protection of light metal alloys in shipbuilding and similar applications The corrosion of Al and its alloys in seawater is due to the high anion defect concentration in the (natural or artificial) oxide skin; this structure facilitates anion adsorption (in particular adsorption of the small chloride ions), so that Al atoms are dissolved from the crystal and pitting corrosion may appear. This danger can be eliminated by Zn coatings on Al or by coupling Al with galvanized steel. This measure results in a certain anodic protection and an enforced general uniform corrosion. Flame-sprayed Zn coatings turn out to be most efficient while Cd coatings are clearly inferior. On the basis of experience gained with the stell/Al couple important variables affecting the corrosion behaviour are potential difference and current density (area ratio) and, in addition, the formation of electrolyte bridges. It is therefore important to prevent the formation of such bridges by careful sealing; it is necessary, however, to take account of the ageing behaviour of the particular sealant.     

A new deal for translation quality

Universal Access in the Information Society - Given the rich body of technical developments and a relatively long history of industrial use of Machine Translation (MT), it is astonishing of how...     

Neuroepithelial bodies in relatively mature lungs: an investigation in prenatal and newborn lambs

Total body and leg bone mineral densities (BMD) were measured in 42 severely handicapped children and adults using a dual energy X-ray absorptiometry (DEXA) (LUNAR Radiation Corp., DPX). Despite the differences in motor ability and nursing history, about 95% of patients, except for 2 cases, were diagnosed as having osteopenia. The degree of osteopenia was dependent on the motor disabilities of their original disease. Therefore we should bear in mind a precaution and therapy from early period. Because BMD of the legs in females were less than -3 SD of the age-matched control values, we should be careful for a possible fracture of femur. Since X-ray hazard of DEXA for patients is considerable to be negligible, this will provide an effective means for quantifying bone mineral in severely handicapped patients.     

Stereological estimation of number and volume of pulmonary neuroepithelial bodies (NEBs) in neonatal hamster lungs

The number and volume of pulmonary neuroepithelial bodies (NEBs) of 1- and 4-week-old hamsters were estimated using unbiased stereological principles and systematic sampling techniques. For comparative purposes, volume estimations were also made in the carotid body, the parathyroid gland, and the adrenal medulla. A significant decrease was found in the total number of NEBs, immunoreactive for CGRP, between 1 and 4 weeks. Individual as well as cumulative NEB volume also decreased significantly. The cumulative NEB volume in 1-week-old hamsters was in the same range as the volumes of the carotids and parathyroids in the same animals. The postnatal decrease of the NEB number suggests that the NEBs are of primary potential importance in the neonatal stage, when they may complement the chemoreceptor function of the carotid bodies, which are relatively inactive at birth. Since the cumulative NEB volume (at least at the age of 1 week) is equal to that of the carotid bodies and the parathyroids, their physiological function may be of similar importance.     

Caged CO2 for the Direct Observation of CO2‐Consuming Reactions

CO₂‐consuming reactions, in particular carboxylations, play important roles in technical processes and in nature. Their kinetic behavior and the reaction mechanisms of carboxylating enzymes are difficult to study because CO₂ is inconvenient to handle as a gas, exists in equilibrium with bicarbonate in aqueous solution, and typically yields products that show no significant spectroscopic differences from the reactants in the UV/Vis range. Here we demonstrate the utility of 3‐nitrophenylacetic acid and related compounds (caged CO₂) in conjunction with infrared spectroscopy as widely applicable tools for the investigation of such reactions, permitting convenient measurement of the kinetics of CO₂ consumption. The use of isotopically labeled caged CO₂ provides a tool for the assignment of infrared absorption bands, thus aiding insight into reaction intermediates and mechanisms.