Brugia malayi microfilariae adhere to human vascular endothelial cells in a C3-dependent manner

Brugia malayi causes the human tropical disease, lymphatic filariasis. Microfilariae (Mf) of this nematode live in the bloodstream and are ingested by a feeding mosquito vector. Interestingly, in a remarkable co-evolutionary adaptation, Mf appearance in the peripheral blood follows a circadian periodicity and reaches a peak when the mosquito is most likely to feed. For the remaining hours, the majority of Mf sequester in the lung capillaries. This circadian phenomenon has been widely reported and is likely to maximise parasite fitness and optimise transmission potential. However, the mechanism of Mf sequestration in the lungs remains largely unresolved. In this study, we demonstrate that B. malayi Mf can, directly adhere to vascular endothelial cells under static conditions and under flow conditions, they can bind at high (but not low) flow rates. High flow rates are more likely to be experienced diurnally. Furthermore, a non-periodic nematode adheres less efficiently to endothelial cells. Strikingly C3, the central component of complement, plays a crucial role in the adherence interaction. These novel results show that microfilariae have the ability to bind to endothelial cells, which may explain their sequestration in the lungs, and this binding is increased in the presence of inflammatory mediators

Utilizing heat regeneration within hydraulic pressure accumulator

Tekniikan kehittyessä toimilaitteiden ja järjestelmien suunnittelussa ja toteutuksessa laitteiden ja koneiden energia- ja kustannustehokkuus nousevat jatkuvasti tärkeämpään rooliin. Hydraulisilla toimilaitteilla saavutetaan korkea tehotiheys, mutta järjestelmien kokonaishyötysuhde on usein heikko. Hyötysuhdetta voidaan nostaa lisäämällä järjestelmiin energian talteenotto, jolloin työkierroista voidaan normaalisti hukkaan menevää energiaa varastoida ja käyttää uudelleen seuraavassa työkierrossa. Hydraulisissa energian talteenottojärjestelmissä energiaa varastoidaan tyypillisesti hydraulipaineakkuihin. Paineakuissa energia varastoituu puristamalla paineakun kaasutilavuudessa olevaa kaasua. Puristusvaiheen aikana kaasun lämpötila nousee ja lämpö alkaa virrata paineakusta ympäristöön. Tämä energian virtaaminen ympäristöön muodostaa merkittävimmän yksittäisen paineakun hyötysuhdetta laskevan tekijän. Tämän työn tavoitteena oli nostaa mäntäpaineakun hyötysuhdetta hyödyntämällä lämmön regenerointia. Lämmön regeneroinnilla pyritään varastoimaan kaasussa puristusvaiheessa syntyvä lämpöenergia lämpöregeneraattoriin ja luovuttamaan energia takaisin kaasuun paineakun purkusyklin aikana. Työssä suunniteltu lämpöregeneraattori perustui faasimuutosmateriaalien hyödyntämiseen energiavarastona. Faasimuutosmateriaalit soveltuvat erinomaisesti lämpövarastoiksi, sillä ne kykenevät sitomaan suuren määrän energiaa faasimuutoksen aikana, jolloin työssä suunniteltu lämpöregeneraattori saatiin mahdutettua mäntäpaineakun sisälle. Työssä saatujen mittaustuloksien perusteella pääteltiin, että lämpöregeneraattorin dynamiikan merkitys nousi merkittävämmäksi kuin lämpöregeneraattorin kyky varastoida lämpöenergiaa. Lämpöregeneraattorin hidas dynamiikka ei mahdollista tehokasta energian talteenottoa nopeista puristus- tai purkusykleistä, ja tämän takia lämpöregeneraattorista saatava hyöty jäi pieneksi. Työssä toteutetulla lämpöregeneraattorilla saavutettiin parhaimmillaan 3 prosenttiyksikön hyötysuhteen nousu verrattaessa samaan mäntäpaineakkuun ilman lämmön regenerointia.As new technological advances are made the importance of energy efficiency and cost effective solutions are even more important when designing and producing new machine systems. Hydraulic systems offer great performance in different actuators, but the general efficiency of the whole hydraulic systems is usually low. Energy efficiency can be improved by utilizing energy recovery systems. With energy recovery some of the normally wasted energy can be recovered and used in the next work cycle. Hydraulic energy recovery systems usually store energy in hydraulic pressure accumulators. Within the hydraulic pressure accumulator, energy is stored by compressing gas inside the accumulator’s gas volume. When compressing gas, heat builds up within the gas and temperature difference between the gas and its surroundings causes heat energy to flow out of the gas. This energy flow is the single most significant factor lowering energy efficiency of the accumulator. The goal of this study was to increase the efficiency of piston type hydraulic pressure accumulator by utilizing heat regeneration. With heat regeneration, heat energy that is generated in the gas during compression cycle is stored in the heat regenerator to be released during the following decompression cycle. Heat regenerator designed in this study utilizes phase change materials to store heat energy. Phase change materials absorb a lot of energy during phase change and thus they are commonly used as heat storages. The results obtained in this study indicate that the dynamic properties of the heat regenerator are more important than the capability to store heat energy. Low dynamic properties prevent the heat regenerator from storing and releasing energy effectively during fast compression and decompression cycles. With the heat regenerator designed in this study the energy efficiency of the accumulator increased by maximum of 3 percentage units when compared to the same accumulator without heat regeneration

Photoluminescence Spectroscopy Applied to Semiconducting Nanowires: A Valuable Probe for Assessing Lattice Defects, Crystal Structures, and Carriers' Temperature

Photoluminescence (PL) spectroscopy is a reliable, non-invasive tool widely employed to investigate the electronic properties of semiconductors and their nanostructures near the band-gap edge states. PL is particularly relevant for determining the energy and symmetry properties of excitons as well as the nature and relative abundances of defects in a semiconductor material. In this chapter, we will present PL measurements on InP nanowires (NWs), a notable material system for NW structures. We address the electronic and defect properties of wurtzite NWs, and provide a comparison with the zincblende counterpart. PL as a function of various external parameters, such as photoexcited carrier density and temperature, allows us to assign the origin of various recombination bands typically observed in InP NWs grown by selective area epitaxy or by vapor--liquid--solid method. The possibility to explore the density of states of NWs is implemented by PL-excitation measurements as a function of polarization, which unveil the optical selection rules pertinent to the wurtzite crystal phase. Finally, a careful analysis of the PL lineshape provides also access to carriers' temperature and thus precious insight on carrier relaxation phenomena that occur in thin NWs