Parasitic manipulation or by-product of infection: an experimental approach using trematode-infected snails

Natural selection should favour parasite genotypes that manipulate hosts in ways that enhance parasite fitness. However, it is also possible that the effects of infection are not adaptive. Here we experimentally examined the phenotypic effects of infection in a snail–trematode system. These trematodes (Atriophallophorus winterbourni) produce larval cysts within the snail's shell (Potamopyrgus antipodarum); hence the internal shell volume determines the total number of parasite cysts produced. Infected snails in the field tend to be larger than uninfected snails, suggesting the hypothesis that parasites manipulate host growth so as to increase the space available for trematode reproduction. To test the hypothesis, we exposed juvenile snails to trematode eggs. Snails were then left to grow for about one year in 800-l outdoor mesocosms. We found that uninfected males were smaller than uninfected females (sexual dimorphism). We also found that infection did not affect the shell dimensions of males. However, infected females were smaller than uninfected females. Hence, infection stunts the growth of females, and (contrary to the hypothesis) it results in a smaller internal volume for larval cysts. Finally, infected females resembled males in size and shape, suggesting the possibility that parasitic castration prevents the normal development of females. These results thus indicate that the parasite is not manipulating the growth of infected hosts so as to increase the number of larval cysts, although alternative adaptive explanations are possible.

The Impact of Head Model Choice on the In Vitro Evaluation of Aerosol Drug Delivery

There are variations in the values reported for aerosol drug delivery across in vitro experiments throughout the published literature, and often with the same devices or similar experimental setups. Factors contributing to this variability include, but are not limited to device type, equipment settings, drug type and quantification methods. This study assessed the impact of head model choice on aerosol drug delivery using six different adults and three different paediatric head models in combination with a facemask, mouthpiece, and high-flow nasal cannula. Under controlled test conditions, the quantity of drug collected varied depending on the choice of head model. Head models vary depending on a combination of structural design differences, facial features (size and structure), internal volume measurements and airway geometries and these variations result in the differences in aerosol delivery. Of the widely available head models used in this study, only three were seen to closely predict in vivo aerosol delivery performance in adults compared with published scintigraphy data. Further, this testing identified the limited utility of some head models under certain test conditions, for example, the range reported across head models was aerosol drug delivery of 2.62 ± 2.86% to 37.79 ± 1.55% when used with a facemask. For the first time, this study highlights the impact of head model choice on reported aerosol drug delivery within a laboratory setting and contributes to explaining the differences in values reported within the literature.

Lipid Vesicles and Other Polymolecular Aggregates—From Basic Studies of Polar Lipids to Innovative Applications

Lipid vesicles (liposomes) are a unique and fascinating type of polymolecular aggregates, obtained from bilayer-forming amphiphiles—or mixtures of amphiphiles—in an aqueous medium. Unilamellar vesicles consist of one single self-closed bilayer membrane, constituted by the amphiphiles and an internal volume which is trapped by this bilayer, whereby the vesicle often is spherical with a typical desired average diameter of either about 100 nm or tens of micrometers. Functionalization of the external vesicle surface, basically achievable at will, and the possibilities of entrapping hydrophilic molecules inside the vesicles or/and embedding hydrophobic compounds within the membrane, resulted in various applications in different fields. This review highlights a few of the basic studies on the phase behavior of polar lipids, on some of the concepts for the controlled formation of lipid vesicles as dispersed lamellar phase, on some of the properties of vesicles, and on the challenges of efficiently loading them with hydrophilic or hydrophobic compounds for use as delivery systems, as nutraceuticals, for bioassays, or as cell-like compartments. Many of the large number of basic studies have laid a solid ground for various applications of polymolecular aggregates of amphiphilic lipids, including, for example, cubosomes, bicelles or—recently most successfully—nucleic acids-containing lipid nanoparticles. All this highlights the continued importance of fundamental studies. The life-saving application of mRNA lipid nanoparticle COVID-19 vaccines is in part based on year-long fundamental studies on the formation and properties of lipid vesicles. It is a fascinating example, which illustrates the importance of considering (i) details of the chemical structure of the different molecules involved, as well as (ii) physical, (iii) engineering, (iv) biological, (v) pharmacological, and (vii) economic aspects. Moreover, the strong demand for interdisciplinary collaboration in the field of lipid vesicles and related aggregates is also an excellent and convincing example for teaching students in the field of complex molecular systems.

Method of Modelling a Tank with Ribbing using a Spatial Scanner for Optimized Control of Volume Characteristics

Increasing requirements for product quality, whether from the side of technical standards or customers, generate demands on the optimization of measurement and data evaluation processes, which include also dimensional characteristics. The paper deals with determining the volume of the tank of a railway wagon with ribbing. In practice, volume flow meters are usually used to measure the internal volumes of manufactured tanks, which measure the volume of water when filled with water. The method is not only time-consuming but also energy-consuming and generates a large amount of wastewater. Therefore, these obsolete methods are gradually being replaced by those that allow effective inspection of tank wagon dimensions according to the technical documentation. The topic of the paper is a description and verification of the design of a progressive method of determining the internal volume of the tank using a spatial 3D scanner Faro FocusS150 and software processing of measured data. At the same time, verification of compliance with the requirements for the accuracy of determining the internal volume of the tank is presented. The aforementioned methods are therefore compared in terms of accuracy, complexity and time consumption.

POSSIBLE CAUSE OF ABNORMAL COLLAPSE OF THE WORLD TRADE CENTER BULDING

Национальный институт стандартов и технологий (NIST) провел расследование о причинах обрушения Всемирного торгового центра (WTC). Однако до сих пор встречаются суждения о якобы специально подготовленном взрыве зданий WTC некими «заговорщиками». Действительно, для многих наблюдателей и экспертов картина обрушения башен WTC послужила поводом для сомнений - как могли высотные здания относительно ровно, практически вертикально, обрушиться? В связи с этим, в работе обсуждается гипотеза, на основе которой можно объяснить специфический характер обрушения зданий. Лифтовые шахты в зданиях занимали 25% площади на плане. Они были сгруппированы в центре здания. Внутренний объем шахт для лифтов на протяжении 200 метров по высоте равен 120000 м3. Разлившийся авиационный керосин пропитал поверхности стенок лифтовых шахт и создал внутри смесь из паров керосина и воздуха. У керосина в три раза ниже поверхностное натяжение, чем у воды. Поэтому он легко смачивает почти любые поверхности, быстро растекается и пропитывает всё. Для керосина концентрационные границы взрываемости в смеси с воздухом находятся от 0,8 до 5,2%. Энергия паров керосина в лифтовых шахтах, равная нижнему концентрационному пределу взрываемости, эквивалентна 13000 кг ТНТ. При случайной искре происходит объемный взрыв паров керосина в лифтовых шахтах. Энергии взрыва достаточно для разрушения и последующего почти вертикального обрушения здания. The National Institute of Standards and Technology (NIST) has conducted an investigation into the causes of the collapse of the World Trade Center (WTC). However, there are still opinions about the allegedly specially prepared explosion of the WTC buildings by some “conspirators”. For many observers and experts, the picture of the collapse of the WTC towers gave rise to doubts - how could high-rise buildings collapse relatively evenly, almost vertically? The paper discusses a hypothesis on the basis of which it is possible to explain the specific nature of the collapse of these buildings. The elevator shafts were grouped in the center of the building. They occupied 25% of the area on the plan. The internal volume of the elevator shafts over a length of 200 meters in height is equal to 120,000 m3. The spilled aviation kerosene soaked the surfaces of the walls of the elevator shafts and created a mixture of kerosene and air vapors inside. Kerosene has three times lower surface tension than water. Therefore, it easily wets almost any surface, spreads quickly and soaks everything. For kerosene, the concentration limits of explosiveness in a mixture with air are from 0.8 to 5.2%. The energy of kerosene vapors in lift shafts, equal to the lower concentration limit of explosiveness, is equivalent to 13000 kg of TNT. In case of an accidental spark, a volumetric explosion of kerosene vapors occurs in the elevator shafts. The energy of the explosion was enough to destroy the building causing subsequent almost vertical collapse.

Research on Performance of Variable-Lead Rotor Twin Screw Compressor

Twin-screw compressors are widely used in aerodynamics, refrigeration and other fields. The screw rotors are the core component of the screw compressor and affect the performance of the compressor. This paper focuses on variable-lead rotors. A thermal process simulation model considering leakage is established to calculate the efficiency of the compressor. Different lead change methods are compared by evaluating the contact line, exhaust port and simulation results. The results show that the compressor obtains better performance when the lead decreases rapidly on the discharge side. Furthermore, the effects of the wrap angle and internal volume ratio on variable-lead rotors are studied. The work provides a reference for the design of the screw compressor rotor.

Studies of the internal structure of electrical devices and the archaeological heritage by the method of neutron radiography and tomography

The paper presents the results of the study of a series of objects of electrical devices and archaeological heritage by the method of neutron radiography and tomography (VL-10 diode, spark plug, bell, ancient ring, stone). It is shown that the method of neutron radiography and tomography reliably works on samples made of various materials. Neutron radiographic and tomographic studies of the VL-10 diode gave an idea of the internal structure of the diode. Experiments with spark plugs have revealed the causes of its faulty function. According to the tomographic results of the bell, ring and stone, the heterogeneous areas in the internal volume of these objects were revealed. The results obtained are the basis for further research in the field of archaeological heritage and technical devices for special purposes.

Water–Sulfuric Acid Foam as a Possible Habitat for Hypothetical Microbial Community in the Cloud Layer of Venus

The data available at the moment suggest that ancient Venus was covered by extensive bodies of water which could harbor life. Later, however, the drastic overheating of the planet made the surface of Venus uninhabitable for Earth-type life forms. Nevertheless, hypothetical Venusian organisms could have gradually adapted to conditions within the cloud layer of Venus—the only niche containing liquid water where the Earth-type extremophiles could survive. Here we hypothesize that the unified internal volume of a microbial community habitat is represented by the heterophase liquid-gas foam structure of Venusian clouds. Such unity of internal space within foam water volume facilitates microbial cells movements and trophic interactions between microorganisms that creates favorable conditions for the effective development of a true microbial community. The stabilization of a foam heterophase structure can be provided by various surfactants including those synthesized by living cells and products released during cell lysis. Such a foam system could harbor a microbial community of different species of (poly)extremophilic microorganisms that are capable of photo- and chemosynthesis and may be closely integrated into aero-geochemical processes including the processes of high-temperature polymer synthesis on the planet’s surface. Different complex nanostructures transferred to the cloud layers by convection flows could further contribute to the stabilization of heterophase liquid-gas foam structure and participate in chemical and photochemical reactions, thus supporting ecosystem stability.

Spatial variation in the structure of overwintering, remnant Saccorhiza polyschides sporophytes and their associated assemblages

Understanding the structure and richness of natural communities is a fundamental goal of marine ecology, and foundation species such as large macroalgae have a disproportionate role in structuring biodiversity. However, high-resolution information on assemblages associated with macroalgae is lacking for many species and regions. Saccorhiza polyschides is a warm-temperate kelp with a relatively short lifespan (12–18 months), large thallus and bulbous holdfast offering habitat for diverse assemblages. In the UK, S. polyschides populations are thought to have proliferated recently. Here, we quantified the density and habitat structure provided by S. polyschides along a gradient of wave exposure within Plymouth Sound, and examined the composition and diversity of associated faunal assemblages. Density varied significantly between sites but not by wave exposure, while biometric measurements were generally highly variable. Senescing holdfasts from sporophytes offered valuable habitat, with high abundance and richness of associated assemblages, although these varied markedly between sporophytes and sites. Faunal abundance, taxon richness and diversity were significantly higher at fully exposed sites than at moderately exposed sites. Internal volume of holdfasts was positively correlated with faunal abundance and taxon richness. We recorded more than 27 distinct taxa and up to ~600 individuals within a single holdfast. Taxa included three fish species, including a novel observation of the pipefish Nerophis lumbriciformis. Further work is needed to examine seasonality in habitat structure and associated diversity patterns but our study demonstrates that even remnant holdfasts from decaying sporophytes represent a valuable microhabitat that may provide shelter, protection and food during winter.

Numerical Study of Hydrocarbon Charge Reduction Methods in HVAC Heat Exchangers

Required refrigerant charge in heat pump systems with propane is analyzed. Two systems are compared: the first a direct heat pump, with fin-and-tube heat exchangers, and the second an indirect system, with plate heat exchangers with an additional brine-to-air heat exchanger. Each system was considered to be able to work reversibly, with 5~kW design cooling capacity in summer and 8~kW design heating capacity in winter. Two separately developed simulation codes were used to calculate the required refrigerant charge and the efficiency of each of the systems. The charge was reduced by the use of microfinned tubes up to 22% in direct system reduced using microfinned tubes compared to the smooth tube. For the indirect system using specially designed plate heat exchangers with the minimum internal volume, their charge was reduced by up to 66% compared to normal plate heat exchangers.