Studies on hydriding kinetics of some La-based metal hydride alloys

In this paper, the hydriding kinetics of LaNi₅, LaNi_4.7Al_0.3 and LmNi_4.91Sn_0.15 is presented. Experiments were carried out by maintaining the pressure ratio (supply pressure to equilibrium pressure at the mid-point of the pressure–concentration–isotherm) equal to 2 and by maintaining nearly isothermal reaction conditions. Two widely used reaction kinetics models, namely Johnson–Mehl–Avrami (JMA) model and Jander diffusion model (JDM) are considered for the analysis. Two JMA models are considered; in the first model, the order of the reaction is assumed as unit and in the second model, the rate constant is calculated by estimating the order by fitting the reaction kinetics data with a reaction kinetics equation. The activation energy and pre-exponential constants of the above-mentioned alloys are estimated by constructing the Arrhenius plot. Activation energies estimated from the different models are compared and the accurate values of activation energy for the different alloys are determined by comparing the reaction kinetics data obtained from the models with the experimental data. The rate-controlling step of the hydriding reaction is obtained for all the alloys investigated.     

Genetically Encoded Biotin Analogues: Incorporation and Application in Bacterial and Mammalian Cells

The biotin–streptavidin interaction is among the strongest known in nature. Herein, the site-directed incorporation of biotin and 2-iminobiotin composed of noncanonical amino acids (ncAAs) into proteins is reported. 2-Iminobiotin lysine was employed for protein purification based on the pH-dependent dissociation constant to streptavidin. By using the high-affinity binding of biotin lysine, the bacterial protein RecA could be specifically isolated and its interaction partners analyzed. Furthermore, the biotinylation approach was successfully transferred to mammalian cells. Stringent control over the biotinylation site and the tunable affinity between ncAAs and streptavidin of the different biotin analogues make this approach an attractive tool for protein interaction studies, protein immobilization, and the generation of well-defined protein–drug conjugates.     

Effects of MDI content on properties of thermally treated oriented strand board (OSB)

The paper discusses the influence of methylene diphenyl diisocyanate (MDI) content on mechanical properties of thermally post-treated single-layered oriented strand boards (OSB). The OSB differed in adhesive content (3, 4 and 5%) and the high temperature (HT) level of the thermal modification (TM) (untreated, 160, 175 °C). To characterise the mechanical behaviour of the OSB, the modulus of rupture (MOR), modulus of elasticity (MOE), and internal bond (IB) of dry and boiled specimens were determined. In addition, the adsorption and desorption isotherms were investigated. The hygroscopic sorption isotherms were calculated according to the Hailwood-Horrobin equation. It was observed that the MOR and the IB of the post-treated OSB are significantly increased with higher MDI content. An increase of the MDI content from 3% up to 5% is not sufficient to compensate the loss of strength caused by TM. However, an increase of MDI-content of about 1% compensates the significant loss of IB of dry and boiled specimens. The MOE is not influenced by TM. With increased adhesive content, thermally treated and untreated specimens show slightly higher values. The thermal post-treatment of OSB alters the wood-water-interaction. The hygroscopicity is reduced. The higher the HT level, the lower is the sorption behaviour. It was also detected that a higher MDI content does not influence the hygroscopicity.     

Probiotics Affect One‐Carbon Metabolites and Catecholamines in a Genetic Rat Model of Depression

1 Scope

Probiotics may influence one‐carbon (C1) metabolism, neurotransmitters, liver function markers, or behavior.

2 Methods and results

Male adult Flinders Sensitive Line rats (model of depression, FSL; n = 22) received Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 (10⁹ or 10¹⁰ colony‐forming units per day) or vehicle for 10 weeks. The controls, Flinders Resistant Line rats (FRL, n = 8), only received vehicle. C1‐related metabolites were measured in plasma, urine, and different tissues. Monoamine concentrations were measured in plasma, hippocampus, and prefrontal cortex. Vehicle‐treated FSL rats had higher plasma concentrations of betaine, choline, and dimethylglycine, but lower plasma homocysteine and liver S‐adenosylmethionine (SAM) than FRLs. FSL rats receiving high‐dose probiotics had lower plasma betaine and higher liver SAM compared to vehicle‐treated FSL rats. FSLs had higher concentrations of norepinephrine, dopamine, and serotonin than FRLs across various brain regions. Probiotics decreased plasma dopamine in FSLs in a dose‐dependent manner. There were no detectable changes in liver function markers or behavior.

3 Conclusions

Probiotics reduced the flow of methyl groups via betaine, increased liver SAM, and decreased plasma dopamine and norepinephrine. Since these changes in methylation and catecholamine pathways are known to be involved in several diseases, future investigation of the effect of probiotics is warranted.     

搅拌摩擦焊中工艺参数对扭矩的影响

通过在6056—T6的铝合金薄板上设计不同旋转频率、不同下压量的搅拌摩擦点焊试验,测量焊接过程中的搅拌头扭矩、下压作用力和试板温度曲线来研究焊接工艺参数对扭矩的影响.结果表明,在旋转频率相同而下压量不同的试验中,搅拌头扭矩随下压作用力增大而增大,而引起扭矩增大的最主要原因是下压作用力使搅拌区材料的力学性能发生了改变;在下压量相同而旋转频率不同的焊接试验中,搅拌头扭矩随旋转频率升高而减小,但扭矩和旋转频率的乘积(即焊接热输入功率)却随旋转频率升高而增大,分析认为旋转频率通过温度和材料的应变速率两个途径对搅拌头扭矩产生了影响,而温度的影响作用更显著.     

Tethered TGF-β1 in a Hyaluronic Acid-Based Bioink for Bioprinting Cartilaginous Tissues

In 3D bioprinting for cartilage regeneration, bioinks that support chondrogenic development are of key importance. Growth factors covalently bound in non-printable hydrogels have been shown to effectively promote chondrogenesis. However, studies that investigate the functionality of tethered growth factors within 3D printable bioinks are still lacking. Therefore, in this study, we established a dual-stage crosslinked hyaluronic acid-based bioink that enabled covalent tethering of transforming growth factor-beta 1 (TGF-β1). Bone marrow-derived mesenchymal stromal cells (MSCs) were cultured over three weeks in vitro, and chondrogenic differentiation of MSCs within bioink constructs with tethered TGF-β1 was markedly enhanced, as compared to constructs with non-covalently incorporated TGF-β1. This was substantiated with regard to early TGF-β1 signaling, chondrogenic gene expression, qualitative and quantitative ECM deposition and distribution, and resulting construct stiffness. Furthermore, it was successfully demonstrated, in a comparative analysis of cast and printed bioinks, that covalently tethered TGF-β1 maintained its functionality after 3D printing. Taken together, the presented ink composition enabled the generation of high-quality cartilaginous tissues without the need for continuous exogenous growth factor supply and, thus, bears great potential for future investigation towards cartilage regeneration. Furthermore, growth factor tethering within bioinks, potentially leading to superior tissue development, may also be explored for other biofabrication applications.     

High throughput nanofabrication of silicon nanowire and carbon nanotube tips on AFM probes by stencil-deposited catalysts

A new and versatile technique for the wafer scale nanofabrication of silicon nanowire (SiNW) and multiwalled carbon nanotube (MWNT) tips on atomic force microscope (AFM) probes is presented. Catalyst material for the SiNW and MWNT growth was deposited on prefabricated AFM probes using aligned wafer scale nanostencil lithography. Individual vertical SiNWs were grown epitaxially by a catalytic vapor-liquid-solid (VLS) process and MWNTs were grown by a plasma-enhanced chemical vapor (PECVD) process on the AFM probes. The AFM probes were tested for imaging micrometers-deep trenches, where they demonstrated a significantly better performance than commercial high aspect ratio tips. Our method demonstrates a reliable and cost-efficient route toward wafer scale manufacturing of SiNW and MWNT AFM probes.     

Intrinsic 3D Prestressing: A New Route for Increasing Strength and Improving Toughness of Hybrid Inorganic Biocements

Cement is the most consumed resource and is the most widely used material globally. The ability to extrinsically prestress cementitious materials with tendons usually made from steel allows the creation of high‐strength bridges and floors from this otherwise brittle material. Here, a dual setting cement system based on the combination of hydraulic cement powder with an aqueous silk fibroin solution that intrinsically generates a 3D prestressing during setting, dramatically toughening the cement to the point it can be cut with scissors, is reported. Changes of both ionic concentration and pH during cement setting are shown to create an interpenetrating silk fibroin inorganic composite with the combined properties of the elastic polymer and the rigid cement. These hybrid cements are self‐densifying and show typical ductile fracture behavior when dry and a high elasticity under wet conditions with mechanical properties (bending and compressive strength) nearly an order of magnitude higher than the fibroin‐free cement reference.     

A flexible mixed-signal image processing pipeline using 3D chip stacks

This work presents a highly flexible mixed-signal CMOS image sensor suitable for smart camera applications. These systems need to fit different constraints regarding power consumption, speed and quality, and the optimal compromise may differ depending on the application. Moreover, the best implementation of a desired image processing task may be in the analog or the digital domain, or even a combined computation. Different aspects starting from the image sensor and signal acquisition up to the pre-processing in analog and digital domain are investigated in this paper to optimize not just one part of the system, but the whole system altogether. Moreover, it is shown that analog processing algorithms can improve signal quality, processing speed and latency while being able to save power, which is important for real-time systems. In order to be able to carry out spatial operations, the state-of-the-art sensor is modified to be able to read out multiple pixels at the same time. This allows analog spatial filter operations which consume significantly less power. As an example, an averaging filter is described which needs less than 5.3 % of the power–time product of a digital implementation for one computation. To enhance data throughput and flexibility, 3D chip stacking is proposed to partition the sensor in smaller units and enable massively parallel processing.