Development of a multi-detector readout circuitry for ultrahigh energy resolution single-photon imaging applications.

In this paper, we present the design and preliminary performance evaluation of a novel external multi-channel readout circuitry for small-pixel room-temperature semiconductor detectors, namely CdZnTe (CZT) and CdTe, that provide an excellent intrinsic spatial (250 and 500 µm pixel size) and an ultrahigh energy resolution (~1% at 122 keV) for X-ray and gamma-ray imaging applications. An analog front-end printed circuit board (PCB) was designed and developed for data digitization, data transfer and ASIC control of pixelated CZT or CdTe detectors. Each detector unit is 2 cm × 2 cm in size and 1 or 2 mm in thickness, being bump-bonded onto a HEXITEC ASIC, and wire-bonded to a readout detector module PCB. The detectors' front-end is then connected, through flexible cables of up to 10 m in length, to a remote data acquisition system that interfaces with a PC through USB3.0 connection. We present the design and performance of a prototype multi-channel readout system that can read out up to 24 detector modules synchronously. Our experimental results demonstrated that the readout circuitry offers an ultrahigh spectral resolution (0.8 keV at 60 keV and 1.05 keV at 122 keV) with the Cd(Zn)Te/HEXITEC ASIC modules tested. This architecture was designed to allow easy expansion to accommodate a larger number of detector modules, and the flexibility of arranging the detector modules in a large and deformable detector array without degrading the excellent energy resolution.

Effects of Whole-Body Electromyostimulation on the Energy-Restriction-Induced Reduction of Muscle Mass During Intended Weight Loss.

Purpose: Overweight and obesity are an increasing problem worldwide. However, most studies that focus on weight reduction by energy restriction and/or aerobic exercise reported considerable loss of muscle mass as well. Increased protein intake and/or resistance exercise might inhibit this detrimental effect during a negative energy balance. Whole-body electromyostimulation (WB-EMS), a time effective, joint-friendly, and highly customizable training technology, showed similar hypertrophic effects compared with high-intensity resistance training. The aim of this study is to evaluate the effect of WB-EMS on body composition during negative energy balance with maintained/increased protein intake in overweight premenopausal women. Patients and Methods: Ninety premenopausal, 25-50-year-old, overweight women were randomly assigned to three groups (n = 30 each). (1) Negative energy balance (-500 kcal/day) by energy restriction with compensatory protein intake (CG). (2) Negative energy balance (-500 kcal/day) by energy restriction (-250 kcal/day) and increased physical activity (-250 kcal/day) with increased protein intake (PA). (3) Negative energy balance (-500 kcal/day) due to energy restriction and increased physical activity with increased protein intake plus WB-EMS. The duration of the intervention was 16 weeks. Participants underwent restrictions in kcal per days and supplementation of protein (CG: 1.2 or PA/WB-EMS: 1.7 g/kg body mass/day) where needed. Bipolar WB-EMS was applied 1.5× week for 20 min (85 Hz; 350 µs; intermittent 6 s impulse, 4 s rest; rectangular). The primary study endpoint "lean body mass" (LBM) and secondary endpoint body fat mass (BFM) were assessed by bio-impedance analysis (BIA). Results: LBM decreased in the CG and PA group (CG: -113 ± 1,872 g; PA: -391 ± 1,832 g) but increased in the WB-EMS group (387 ± 1,769 g). However, changes were not significant (p > 0.05). Comparing the groups by ANOVA, no significant differences were observed (p = 0.070). However, pairwise adjusted comparisons determined significant differences between WB-EMS and PA (p = 0.049). BFM decreased significantly (p < 0.001) in all groups (CG: -2,174 ± 4,331 g; PA: -3,743 ± 4,237 g; WB-EMS: -3,278 ± 4,023 g) without any significant difference between the groups (ANOVA: p = 0.131). Conclusion: WB-EMS is an efficient, joint-friendly, and highly customizable training technology for maintaining muscle mass during energy restriction and can thus be considered as an alternative to more demanding resistance exercise protocols.

Impact of multivalent charge presentation on peptide-nanoparticle aggregation.

Strategies to achieve controlled nanoparticle aggregation have gained much interest, due to the versatility of such systems and their applications in materials science and medicine. In this article we demonstrate that coiled-coil peptide-induced aggregation based on electrostatic interactions is highly sensitive to the length of the peptide as well as the number of presented charges. The quaternary structure of the peptide was found to play an important role in aggregation kinetics. Furthermore, we show that the presence of peptide fibers leads to well-defined nanoparticle assembly on the surface of these macrostructures.

Exploiting Oligo(amido amine) Backbones for the Multivalent Presentation of Coiled-Coil Peptides.

The investigation of coiled coil formation for one mono- and two divalent peptide-polymer conjugates is presented. Through the assembly of the full conjugates on solid support, monodisperse sequence-defined conjugates are obtained with defined positions and distances between the peptide side chains along the polymeric backbone. A heteromeric peptide design was chosen, where peptide K is attached to the polymer backbone, and coiled-coil formation is only expected through complexation with the complementary peptide E. Indeed, the monovalent peptide K-polymer conjugate displays rapid coiled-coil formation when mixed with the complementary peptide E sequence. The divalent systems show intramolecular homomeric coiled-coil formation on the polymer backbone despite the peptide design. Interestingly, this intramolecular assembly undergoes a conformational rearrangement by the addition of the complementary peptide E leading to the formation of heteromeric coiled coil-polymer aggregates. The polymer backbone acts as a template bringing the covalently bound peptide strands in close proximity to each other, increasing the local concentration and inducing the otherwise nonfavorable formation of intramolecular helical assemblies.