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Quasioptic, Calibrated, Full 2-port Measurements of Cryogenic Devices under Vacuum in the 220- 330 GHz Band
No full textA quasi-optical (QO) test bench was designed, simulated, and calibrated for characterizing all four S-parameters of devices in the 220–330 GHz (WR3.4) frequency range, from room temperature down to 4.8 K. Quasioptical calibration methods were applied to de-embed the impact of cryostat and optical elements on device under test measurements. The devices were measured through vacuum windows via focused beam radiation. A de-embedding method employing line-reflect-match (LRM) calibration was established to account for the effects of optical components and vacuum windows. Such a method does not require multiple line standards inside the cryostat and mechanical translation of quasioptics. System validation was performed with measurements of cryogenically cooled devices, such as bare silicon wafers and stainless-steel frequency-selective surface (FSS) bandpass filters, and superconducting bandpass FSS fabricated in niobium. A permittivity reduction of Si based on a 4 GHz resonance shift was observed concomitant with a drop in temperature from 296 to 4.8 K. The stainless steel FSS measurements revealed a relatively temperature invariant center frequency and return loss level of 263 GHz and 35 dB on average, respectively. Finally, a center frequency of 257 GHz was measured with the superconducting filters, with return loss improved by 11 dB on average at 4.8 K. To the best of our knowledge, this is the first reported attempt to scale LRM calibration to 330 GHz and use it to de-embed the impact of optics and cryostat from cryogenically cooled device S-parameters.</p
A biofluid-repellent nanograss coating enhances flow of protein solutions and preserves transparency of glass capillaries upon exposure to blood
No full textA transparent and superhydrophobic (SHB) nanograss coating makes glass capillaries repellent toward protein solutions and blood. The coating is fabricated using atomic layer deposited alumina which is converted into grass-like alumina (GLA) by hot water treatment (HWT). The resulting tubes are transparent and highly repellent towards water and protein solutions (sliding angle <6° for a concentrated albumin solution). The biofluid repellence of the coating reduces hydraulic resistances for protein-rich biofluids, including fetal bovine serum, by 0–50% with the strongest effect for the smallest tubes and lowest Reynolds numbers. This work addresses a knowledge gap where previous studies have mostly focused on pure water for the drag reduction effect. The tubes also show a promising ability to stay clean and transparent on short term exposure to blood, unlike unmodified glass or polymer controls
Static Light Scattering for Lignin Particle Size Characterization
No full textLignin, a widely available and renewable organic polymer, has several desirable properties and applications. However, as a by-product of pulp and paper industry, it is mainly burned for energy. Limited understanding of the complex and heterogeneous structure and a shortage of tailored analysis methods hinder its utilization in higher value applications. This study describes and compares the use of two different static light scattering methods, laser diffraction and small-angle light scattering (SALS), for studying lignin particle size in suspension. The results from laser diffraction showed that the selected particle concentration and absorption coefficient affect the measured sizes especially for particles <1 µm in diameter. For irregularly shaped particles with broad size distributions, sampling is the most important parameter affecting the results. SALS proved an efficient method for obtaining information on particle aggregation by providing primary particle sizes as well as aggregate sizes. Characterization of samples with spherical particles and narrow size distributions is straightforward with both laser diffraction and SALS, whereas the interpretation of results for more heterogeneous samples is less obvious. Static light scattering methods could make lignin particle size analysis more rapid and automated, thus enhancing lignin valorization, but should be applied carefully to avoid systematic errors
Cascade synthesis of diarylamines catalyzed by oxygen-rich and porous carbon
No full textActivated carbon derived porous materials, effectively enriched with OH and C[double bond, length as m-dash]O groups, were found to mediate, in a cascade manner, the condensation between anilines and 3-hexenones or β-tetralones, followed by their aromatization to diarylamines. The reaction proceeds via in situ formation of enamine intermediates which are subsequently oxidatively dehydrogenated in presence of a molecular oxidant under inert atmosphere. The functional groups on the carbon surface contributed actively to the catalysis: phenolic hydroxyl groups were found to promote the coupling of amines and ketones to imines and their tautomerization to enamines, while the C[double bond, length as m-dash]O groups of the quinoidic moieties catalyze the dehydrogenative aromatization step. The carbon material's extensive porous structure turns out to be critical to preserve the reactive β,γ-unsaturated cyclohexanone derivatives and their enamine intermediates from undesirable coupling and condensation side-reactions. The carbocatalyst can be regenerated by molecular N-oxo quinoline, which acts as a more convenient and cleaner stoichiometric oxidant in comparison with standard aerobic conditions (oxygen-rich atmosphere). The developed methodology delivered up to 93% yields for many diarylamines, formerly accessible exclusively via Pd-mediated couplings. Computational DFT study of possible enamine reaction modes with quinone model compounds, combined with kinetic isotope effects (KIE) suggest that the aromatization reaction is triggered by hydride abstraction at the benzylic position of the enamine intermediate
Thermoelectric and electronic transport properties of thermal and plasma-enhanced ALD grown titanium nitride thin films
No full textTitanium nitride (TiN) thin films demonstrate high electrical conductivity and thermal stability up to 400 °C in ambient conditions, with stability extending to 600–800 °C under inert or vacuum environments. Unlike many metals and transition metal nitrides, TiN combines high carrier mobility with moderate carrier concentration, making it ideal for thermal management and power-efficient applications in nanoelectronics and energy harvesting. This study systematically investigates the thermoelectric and electronic transport properties of TiN films grown by plasma-enhanced atomic layer deposition (PEALD), comparing them to those produced using traditional thermal atomic layer deposition (thermal ALD). These properties are studied as a function of growth temperature and the number of growth cycles. In particular, TiN films deposited by PEALD at 400 °C for 2000 ALD cycles exhibited a remarkable power factor of 512 µW m−1K−2at room temperature compared to a power factor of 4.95 µW m−1K−2measured for thermal ALD films fabricated under the same deposition conditions. Additionally, thermal conductivity was also measured for thicker TiN films (86 nm), yielding values of 26.96 W m−1K−1for PEALD and 7.01 W m−1K−1for thermal ALD, marking the first such report for ALD-grown TiN. These values offer an upper estimate of the thermal behavior in thinner films. Based on these measured properties, the thermoelectric figure of merit (zT) at room temperature was calculated to be 0.0056 for PEALD TiN films which is significantly higher than the value of 0.0002 obtained for thermal ALD TiN films. Our findings provide critical insights into transport properties of TiN, offering guidance for the development of conductive nanolayers in thermoelectric, nanoelectronic, and on-chip cooling applications, where precise control over thermal and electronic behavior is vital, thereby expanding the relevance of ALD TiN in high-performance applications.</p
Semi-quantitative Lateral Flow Assay Using a Handheld Device with a Transmissive Readout
No full textLateral flow assays (LFAs) are widely used for rapid and cost-effective diagnostic testing. The assays are often qualitative relying on a binary interpretation of the results on test strips. In many applications, however, quantitative or semi-quantitative readout is needed to define the analyte molecule concentration in a sample matrix, such as, saliva or urine. This study focuses on developing a semi-quantitative LFA test concept with a customized test strip cartridge and transmissive optical detection. LFA was developed to detect Covid-19 proteins and the coloration of the test line was induced by the concentration of plasmonic nanoparticles. Spectroscopic characterization of the test strips showed that the signal strength was enhanced by 82% on average when the conventional reflection-based detection was substituted by a transmission detection. When a set of LFA tests were read with the developed handheld optoelectronic device, the observed standard deviation was found to be below 3% meeting the requirements for semi-quantitative analyses.</p
Kiinnostus fuusioenergiaa kohtaan kasvaa
No full textFuusioenergiaa on pitkään pidetty tulevaisuuden suurena toivona - vaihtoehtona, jonka avulla voidaan tuottaa mittavia määriä puhdasta energiaa. Viime vuosina alalla on nähty enemmän kehitystä kuin useisiin aiempiin vuosikymmeniin yhteensä: uusia maailmanennätyksiä on syntynyt, ja yli 50 uutta yritystä on perustettu
Techno-functional and nutritional evaluation of Solein single-cell protein and its application in non-dairy yoghurt alternatives
No full textThe growing global population and climate crisis demand expanding non-animal protein options. Single-cell protein biomass, referred to as “Solein”, is produced by the hydrogen-oxidising bacterium Xanthobacter sp. SoF1 and is a promising, sustainable source of protein and dietary fibre, especially when created using renewable energy. This study investigates Solein protein powder (SPP) for its composition and techno-functional properties, comparing it to pea protein isolate (PPI). SPP had a lower fat content and higher dietary fibre, while matching the protein content of PPI. SPP met all indispensable amino acid requirements for adults over the age of three, as outlined by the FAO in 2013. A milk alternative resembling semi-skimmed cow's milk was produced from SPP and PPI. These emulsions were fermented with a commercial starter culture containing Streptococcus thermophilus. The fermentation process was monitored by tracking pH, total titratable acidity, and microbial growth. The resulting yoghurt alternative (YA) underwent textural and rheological analysis. Solein protein powder yoghurt alternative (SPP-YA) exhibited faster acidification, greater microbial growth, improved water retention, and a texture similar to dairy yoghurt. Static in vitro digestion revealed moderate protein digestibility of the non-fermented SPP emulsion (63.8–67.5%), based on total amino acids, free amino groups, and total nitrogen, with an in vitro Digestible Indispensable Amino Acid Score (DIAAS) of (51.0 ± 6.1%). Fermentation slightly reduced digestibility (57.8–59.6%) and DIAAS (48.3 ± 1.4%), with isoleucine as the limiting amino acid. This work provides the first insight into the structural and nutritional performance of hydrogen-oxidising bacterial protein in non-dairy YA.</p
Tuning physical performance of gelatin-cellulose nanocrystals hydrogels
No full textStimuli-responsive hydrogels are interesting, particularly in the realm of biomedicals, but often the fundamental response of their key physical properties is not simultaneously monitored. Here, we investigated the pH response on the porosity, rheological behavior, mechanical performance, and molecular diffusivity of a hydrogel system composed of two bio-based components: gelatin and rod-like cellulose nanocrystals (CNCs). By leveraging the pH-responsive nature of gelatin, we systematically examined the structural properties of these hydrogels formed under three pH conditions: below (pH 5), above (pH 11), and at the isoelectric point (pH 8) of type A gelatin. All hydrogels exhibited a distinct cellular architecture, characterized by micron-scale tubular pores with embedded mesopores. Increasing pH upon the hydrogel crosslinking promoted the formation of more porous structures with significantly enhanced mechanical performance. The effect on the Young's modulus was significant: with a 3-fold increase compared to its counterparts, the hydrogel fabricated at pH 11 exhibited the stiffest structure. This improvement in hydrogel stiffness with pH further restricted the molecular diffusivity within the hydrogels to some extent, as evidenced by Fluorescence Recovery After Photobleaching analysis using fluorescein isothiocyanate-dextran as a diffusion probe. Overall, this study presents a straightforward and effective strategy for fabricating pH-tunable hydrogels, providing valuable insights for the design of responsive biomaterials with potential applications in soft tissue engineering and drug delivery.</p
Feasibility of evacuation from the front line using unmanned ground vehicles during platoon-level defensive combat
No full textIntroduction Advancements in technology and intelligence, as well as deliberate targeting of medical personnel and vehicles, have made casualty extraction increasingly hazardous. The Russo-Ukrainian War has further demonstrated that the rapid development of unmanned technologies may also enable novel approaches. Although some of these systems have been deployed, reporting on their performance is scarce and understandably incomplete, which limits their evidence-based and effective integration with fighting forces. This paper addresses this gap by presenting preliminary findings on potential ranges of evacuation unmanned ground vehicles (UGVs) utilisation. Methods A virtual simulation experiment was conducted, where a platoon defended against a mechanised infantry company. The experiment was a repeated military exercise with different groups of participants. The defending force had evacuation UGVs, which were placed close behind the defensive line. The aim was to determine whether UGVs could survive long enough to support evacuation and whether evacuation could be carried out before the conflict ended. Furthermore, the availability of UGVs and the likelihood that an evacuation attempt could avoid enemy interference were assessed. The experiment involved 470 participants divided into 11 groups. Each participant completed four combat scenarios. Players of each group switched sides and environments. In total, 44 instances of skirmishes were fought in a virtual simulation environment. Results The simulation results indicated UGV loss rate of 53%. Evacuations were attempted in 45% of skirmishes. Furthermore, 81% of initiated evacuation attempts were successful. Conclusions The experiment provided estimates of evacuation UGV loss rates near the defence line amid active conflict. It also offered evidence on the feasibility of initiating evacuation before the active conflict had fully ceased, and the likelihood of the moving evacuation vehicle encountering enemy fire. These findings can guide decisions on whether the risk of losing small evacuation vehicles and their equipment is acceptable when deployed near front lines.</p