Open Access

Silk-fibroin is utilized as a biocompatible and bioresorbable enzymeimmobilization matrix and exemplarily demonstrated for a screen-printedamperometric glucose biosensor. The silk-fibroin is derived from the silkwormBombyx mori. The enzyme immobilization matrix consisting of silk-fibroin,together with glucose oxidase from Aspergillus niger, is applied to a screen-printed carbon-based, biocompatible, and biodegradable working electrode ona flexible silk-fibroin substrate. The biosensor is characterized electrochemicallyat physiological glucose concentrations in the range from 0.5 to 10 mm. Theresults are compared to a “conventional” glucose biosensor, also fabricated ona flexible silk-fibroin substrate, however utilizing a laboratory standard enzymeimmobilization matrix based on bovine serum albumin and glutaraldehyde.Furthermore, the influence of pH (pH 5.5 to pH 8.0) and temperature variations(21 to 70 °C) on these two different immobilization matrices are studied.

The industrial production of citric acid, an ingredient in beverages, pharmaceuticals, and cosmetics, is based on microbial fermentation of glucose or sucrose. Given the elevated cost of these sugars, lignocellulosic biomass is emerging as a cost-effective and environmentally friendly feedstock for sustainable bioprocesses. However, fermentation of lignocellulosic materials requires that they are first broken down enzymatically. This can be achieved by the filamentous fungus Aspergillus niger, which has the ability to secrete hydrolytic enzymes and to produce citric acid. Here, we investigated the production of citric acid using a consolidated bioprocess, in which all conversion steps – from the solid substrate to the final product – occurred in a single process stage. The press cake derived from a perennial ryegrass (Lolium perenne) was used as substrate and glucose or the remaining press juice were utilized as an additional carbon source. Aspergillus niger produced citrate successfully only when the press cake was supplemented with press juice (2.1 ± 0.0 g kgDM−1) and especially glucose (84.7 ± 0.3 g kgDM−1). Confocal laser scanning microscopy revealed differences in fungal mycelia based on the carbon source supplemented. Overall, the results indicate the successful implementation of solid-state fermentation for the sustainable production of citric acid by A. niger fed on press cake.

The aim of the current study was to investigate the performance of integrated RF transmit arrays with high channel count consisting of meander microstrip antennas for body imaging at 7 T and to optimize the position and number of transmit ele- ments. RF simulations using multiring antenna arrays placed behind the bore liner were performed for realistic exposure conditions for body imaging. Simulations were performed for arrays with as few as eight elements and for arrays with high channel counts of up to 48 elements. The B1+ field was evaluated regarding the degrees of freedom for RF shimming in the abdomen. Worst-case specific absorption rate (SARwc ), SAR overestimation in the matrix compression, the number of virtual obser- vation points (VOPs) and SAR efficiency were evaluated. Constrained RF shimming was performed in differently oriented regions of interest in the body, and the devia- tion from a target B1+ field was evaluated. Results show that integrated multiring arrays are able to generate homogeneous B1+ field distributions for large FOVs, espe- cially for coronal/sagittal slices, and thus enable body imaging at 7 T with a clinical workflow; however, a low duty cycle or a high SAR is required to achieve homoge- neous B1+ distributions and to exploit the full potential. In conclusion, integrated arrays allow for high element counts that have high degrees of freedom for the pulse optimization but also produce high SARwc , which reduces the SAR accuracy in the VOP compression for low-SAR protocols, leading to a potential reduction in array performance. Smaller SAR overestimations can increase SAR accuracy, but lead to a high number of VOPs, which increases the computational cost for VOP evaluation and makes online SAR monitoring or pulse optimization challenging. Arrays with interleaved rings showed the best results in the study.

Subtilisins from microbial sources, especially from the Bacillaceae family, are of particular interest for biotechnological applications and serve the currently growing enzyme market as efficient and novel biocatalysts. Biotechnological applications include use in detergents, cosmetics, leather processing, wastewater treatment and pharmaceuticals. To identify a possible candidate for the enzyme market, here we cloned the gene of the subtilisin SPFA from Fictibacillus arsenicus DSM 15822ᵀ (obtained through a data mining-based search) and expressed it in Bacillus subtilis DB104. After production and purification, the protease showed a molecular mass of 27.57 kDa and a pI of 5.8. SPFA displayed hydrolytic activity at a temperature optimum of 80 °C and a very broad pH optimum between 8.5 and 11.5, with high activity up to pH 12.5. SPFA displayed no NaCl dependence but a high NaCl tolerance, with decreasing activity up to concentrations of 5 m NaCl. The stability enhanced with increasing NaCl concentration. Based on its substrate preference for 10 synthetic peptide 4-nitroanilide substrates with three or four amino acids and its phylogenetic classification, SPFA can be assigned to the subgroup of true subtilisins. Moreover, SPFA exhibited high tolerance to 5% (w/v) SDS and 5% H₂O₂ (v/v). The biochemical properties of SPFA, especially its tolerance of remarkably high pH, SDS and H₂O₂, suggest it has potential for biotechnological applications.

It has been shown that muscle fascicle curvature increases with increasing contraction level and decreasing muscle–tendon complex length. The analyses were done with limited examination windows concerning contraction level, muscle–tendon complex length, and/or intramuscular position of ultrasound imaging. With this study we aimed to investigate the correlation between fascicle arching and contraction, muscle–tendon complex length and their associated architectural parameters in gastrocnemius muscles to develop hypotheses concerning the fundamental mechanism of fascicle curving. Twelve participants were tested in five different positions (90°/105°*, 90°/90°*, 135°/90°*, 170°/90°*, and 170°/75°*; *knee/ankle angle). They performed isometric contractions at four different contraction levels (5%, 25%, 50%, and 75% of maximum voluntary contraction) in each position. Panoramic ultrasound images of gastrocnemius muscles were collected at rest and during constant contraction. Aponeuroses and fascicles were tracked in all ultrasound images and the parameters fascicle curvature, muscle–tendon complex strain, contraction level, pennation angle, fascicle length, fascicle strain, intramuscular position, sex and age group were analyzed by linear mixed effect models. Mean fascicle curvature of the medial gastrocnemius increased with contraction level (+5 m−1 from 0% to 100%; p = 0.006). Muscle–tendon complex length had no significant impact on mean fascicle curvature. Mean pennation angle (2.2 m−1 per 10°; p < 0.001), inverse mean fascicle length (20 m−1 per cm−1; p = 0.003), and mean fascicle strain (−0.07 m−1 per +10%; p = 0.004) correlated with mean fascicle curvature. Evidence has also been found for intermuscular, intramuscular, and sex-specific intramuscular differences of fascicle curving. Pennation angle and the inverse fascicle length show the highest predictive capacities for fascicle curving. Due to the strong correlations between pennation angle and fascicle curvature and the intramuscular pattern of curving we suggest for future studies to examine correlations between fascicle curvature and intramuscular fluid pressure.