双引擎勇士

历史总是让我们在"喷火"、"野马"、"零"式战斗机和令人恐惧的德国Bf-109等著名飞机上见识到二战的空中神话,它们都是一些单引擎战斗机.事实上我们忘记了,很多同样或类似的任务是由双引擎战机执行的.和它们的单引擎兄弟一样,双引擎飞机也在历史上赢得了一席之地,铸就不少空中传奇. 我们将在本期的杂志中向那些似乎总是被遗忘的...     

Determination of System Function for Some Types of Gamma-Ray Collimators

A method to compute the system function of gamma-ray multichannel collimators having a point spread which is periodic in the angle when expressed in polar coordinates is described. This is the case when the cross section of the channel distribution is hexagonal, for example. The computation is done in terms of sample of the responses to a finite number of lines.     

Ueber Milchuntersuchungen und Milchkontrolle

Ohne Zusammenfassung     

Genetic Bias,Diversity Indices,Physiochemical Properties and CDR3 Motifs Divide Auto-Reactive from Allo-Reactive T-Cell Repertoires

The distinct properties of allo-reactive T-cell repertoires are not well understood. To investigate whether auto-reactive and allo-reactive T-cell repertoires encoded distinct properties, we used dextramer enumeration, enrichment, single-cell T-cell receptor (TCR) sequencing and multiparameter analysis. We found auto-reactive and allo-reactive T-cells differed in mean ex vivo frequency which was antigen dependent. Allo-reactive T-cells showed clear differences in TCR architecture, with enriched usage of specific T-cell receptor variable (TRBJ) genes and broader use of T-cell receptor variable joining (TRBJ) genes. Auto-reactive T-cell repertoires exhibited complementary determining regions three (CDR3) lengths using a Gaussian distribution whereas allo-reactive T-cell repertoires exhibited distorted patterns in CDR3 length. CDR3 loops from allo-reactive T-cells showed distinct physical-chemical properties, tending to encode loops that were more acidic in charge. Allo-reactive T-cell repertoires differed in diversity metrics, tending to show increased overall diversity and increased homogeneity between repertoires. Motif analysis of CDR3 loops showed allo-reactive T-cell repertoires differed in motif preference which included broader motif use. Collectively, these data conclude that allo-reactive T-cell repertoires are indeed different to auto-reactive repertoires and provide tangible metrics for further investigations and validation. Given that the antigens studied here are overexpressed on multiple cancers and that allo-reactive TCRs often show increased ligand affinity, this new TCR bank also has translational potential for adoptive cell therapy, soluble TCR-based therapy and rational TCR design.     

Drastic enhancement of mechanical properties of Ca3Co4O9 by B4C addition

Ca₃Co₄O₉ with B₄C additions in different proportions (0, 0.10, 0.25, 0.5, and 0.75 wt.%) have been fabricated using the classical solid-state method. Powder XRD patterns have displayed that Ca₃Co₄O₉ phase is the major one in all samples. Microstructural observations showed that B₄C has been superficially oxidized, producing liquid B₂O₃ during sintering, and reacting with the Ca₃Co₄O₉ grains to produce bridges between them. In spite of the increase of porosity, these bridges led to an important raise (more than two times) of mechanical properties when compared to the pristine materials. On the other hand, while B₄C addition has not influenced S values, it has decreased electrical resistivity, thermal conductivity, and thermal expansion. Consequently, ZT values have been also increased, reaching 0.24 at 800 °C in 0.25 wt.% B₄C containing samples, which is very close to the best values reported in the literature, and two times higher than the obtained in pure materials in this work.     

Click chemistry‐type crosslinking of a low‐conductivity polyethylene copolymer ternary blend for power cable insulation

High‐voltage direct‐current power cables are vital for the efficient transport of electricity derived from renewable sources of energy. The most widely used material for high‐voltage power cable insulation – low‐density polyethylene (LDPE) – is usually crosslinked with peroxides, a process that releases unwanted by‐products. Hence, by‐product‐free crosslinking concepts that mitigate the associated increase in electrical conductivity are in high demand. Click chemistry‐type crosslinking of polyethylene copolymer mixtures that contain glycidyl methacrylate and acrylic acid co‐monomers is a promising alternative, provided that the curing reaction can be controlled. Here, we demonstrate that the rate of the curing reaction can be adjusted by tuning the number of epoxy and carboxyl groups. Both dilution of copolymer mixtures with neat LDPE and the selection of copolymers with a lower co‐monomer content have an equivalent effect on the curing speed. Ternary blends that contain 50 wt% of neat LDPE feature an extended extrusion window of up to 170 °C. Instead, at 200 °C rapid curing is possible, leading to thermosets with a low direct‐current electrical conductivity of about 10^?16 S cm^?1 at an electric field of 20 kV mm^?1 and 70 °C. The conductivity of the blends explored here is comparable to or even lower than values measured for both ultraclean LDPE and a peroxide‐cured commercial crosslinked polyethylene grade. Hence, click chemistry curing represents a promising alternative to radical crosslinking with peroxides. © 2019 Society of Chemical Industry     

Calcium phosphate growth on sintered α-alumina treated with piranha solution using a wet-chemical procedure

Two alumina samples, a high surface powder γ-alumina and a sintered α-alumina have been studied as substrates for apatite growth. In the first case, the initial stage was the calcium adsorption in an alkaline solution, followed by phosphate uptake. On the other hand, the α-alumina was firstly subjected to an acid piranha treatment at 80 °C for four hours, before alternate immersions on calcium and phosphate solutions. Next, the alumina samples were immersed repeatedly in a glycine buffer, pH 10.2, and then in tris buffer solutions, pH 7.4 at 32 °C. The resultant solids were studied by means of XRD, TEM or SEM. Calcium phosphate growth was observed in both cases. An almost uniform and continuous layer was formed on the sintered α-alumina. The results suggest that pretreatment with piranha solution seems to be a fast and efficient alternative to bioactivate the α-alumina surface.