A switching system based on microcontroller for successive applying of MGT and CPT on MOSFETs

A new, low cost switching system based on PIC 18F4550 microcontroller (MCU), called APL-SM v1.0 system, which enables the successive measuring of both the electrical characteristics in midgap-subthreshold technique (MGT) and charge-pumping currents in charge-pumping technique (CPT) of metal–oxide–semiconductor field effect transistor (MOSFET), has been developed. The APL-SM v1.0 system, instead of expensive switching matrix which price is considerably higher, could be used for the switching from MGT to CPT and vice versa. Using the appropriate program, the system allows the monitoring of MOSFETs during long time periods, helping the performing of long lasting experiments. The good agreement in the electrical characteristics, as well as in the charge-pumping currents, obtained using ultra low current, high speed Keithley switching matrix (SM) and APL-SM system, was obtained.     

Direct potentiometric determination of diastase activity in honey

A novel method for the determination of diastase activity is reported. The method is based on a direct potentiometric measurement of triiodide ion that is released when a starch-triiodide complex is hydrolysed by honey diastase. The increase of free triiodide ion concentration in a sample is found to be directly proportional to the diastase activity of the sample. A response mechanism of the platinum redox electrode is proposed, allowing a calculation of the diastase activity factor (F). The sensor and analyte parameters, including F, were obtained by least squares fitting of potentiometric data using the optimisation function of the Solver add-in of Microsoft Excel. The values of F obtained by the new direct potentiometric method were compared with those obtained using the standard Phadebas method (DN values), and the two values were found to agree within experimental error. Finally, the diastase activity of nine varieties of honey was determined using the novel method developed here.     

Performance Analysis of System with Micro- and Macrodiversity Reception in Correlated Gamma Shadowed Rician Fading Channels

In this paper, the performance of wireless system employing microdiversity to mitigate the effects of short-term fading and macrodiversity to reduce long-term fading (shadowing) effects is studied. The system model assumes implementation of maximal-ratio combining (MRC) at the microlevel and selection combining (SC) at the macrolevel. The received signal envelope follows a Rician distribution and it also suffers gamma shadowing. Novel expressions for the probability density function (PDF), cumulative distribution function (CDF), and moment-generating function (MGF) of the output signal-to-noise ratio (SNR) are obtained. Several useful performance criteria, such as the moments of the output SNR and outage probability are analytically derived. Moreover, the average bit error probability (ABEP) for noncoherent binary differential phase-shift keying (BDPSK) is calculated using the MGF based approach while the ABEP for coherent binary phase-shift keying (BPSK) is studied by averaging the conditional bit error probability over the PDF. Numerical results are graphically presented to show the effects of various system parameters to the system performance, as well as the enhancement due to use of the combination of micro- and macrodiversity. Some of numerical results are complemented by equivalent computer simulated results which validate the accuracy of the proposed analysis. The agreement between the Rician-gamma and Rician-lognormal fading model is also established.     

The Role of Altered Nucleotide Excision Repair and UVB-Induced DNA Damage in Melanomagenesis

UVB radiation is the most mutagenic component of the UV spectrum that reaches the earth’s surface and causes the development of DNA damage in the form of cyclobutane pyrimidine dimers and 6-4 photoproducts. UV radiation usually results in cellular death, but if left unchecked, it can affect DNA integrity, cell and tissue homeostasis and cause mutations in oncogenes and tumour-suppressor genes. These mutations, if unrepaired, can lead to abnormal cell growth, increasing the risk of cancer development. Epidemiological data strongly associates UV exposure as a major factor in melanoma development, but the exact biological mechanisms involved in this process are yet to be fully elucidated. The nucleotide excision repair (NER) pathway is responsible for the repair of UV-induced lesions. Patients with the genetic disorder Xeroderma Pigmentosum have a mutation in one of eight NER genes associated with the XP complementation groups XP-A to XP-G and XP variant (XP-V). XP is characterized by diminished repair capacity, as well as a 1000-fold increase in the incidence of skin cancers, including melanoma. This has suggested a significant role for NER in melanoma development as a result of UVB exposure. This review discusses the current research surrounding UVB radiation and NER capacity and how further investigation of NER could elucidate the role of NER in avoiding UV-induced cellular death resulting in melanomagenesis.     

Second‐Order Statistics of System with Microdiversity and Macrodiversity Reception in Gamma‐Shadowed Rician Fading Channels

In this letter, a wireless communication system with microdiversity and macrodiversity reception in gamma‐shadowed Rician fading channels is considered. Exact and rapidly converging infinite‐series expressions for the average level crossing rate and average fade duration at the output of the system are provided. Numerical results are presented graphically to illustrate the proposed mathematical analysis and to examine the effects of the system's parameters on the quantities considered.     

Structural destabilisation of MgH2 obtained by heavy ion irradiation

MgH₂ powder samples have been irradiated with 120 keV Ar⁺⁸ ions with different ion fluencies ranging from 10¹² to 10¹⁶ ions/cm². Irradiation effects are estimated by SRIM calculations, and investigated experimentally using Raman spectroscopy and X-ray diffraction (XRD) analysis. The observed changes of structure and vibrational spectra are elaborated, their consequences on hydrogen bonding in MgH₂ discussed, and influence on H-desorption properties investigated by Temperature Programmed Desorption (TPD) and Differential Scanning Calorimetry (DSC) techniques. It has been established that near-surface defects have a predominant influence on decreasing the H-desorption temperature. Variations of Raman, TPD and DSC spectra with irradiation conditions suggest that there are several mechanisms of dehydriding, and that they depend on defect concentration, interaction and ordering.     

The Impact of the Microbiome on Resistance to Cancer Treatment with Chemotherapeutic Agents and Immunotherapy

Understanding the mechanisms of resistance to therapy in human cancer cells has become a multifaceted limiting factor to achieving optimal cures in cancer patients. Besides genetic and epigenetic alterations, enhanced DNA damage repair activity, deregulation of cell death, overexpression of transmembrane transporters, and complex interactions within the tumor microenvironment, other mechanisms of cancer treatment resistance have been recently proposed. In this review, we will summarize the preclinical and clinical studies highlighting the critical role of the microbiome in the efficacy of cancer treatment, concerning mainly chemotherapy and immunotherapy with immune checkpoint inhibitors. In addition to involvement in drug metabolism and immune surveillance, the production of microbiota-derived metabolites might represent the link between gut/intratumoral bacteria and response to anticancer therapies. Importantly, an emerging trend of using microbiota modulation by probiotics and fecal microbiota transplantation (FMT) to overcome cancer treatment resistance will be also discussed.     

Structure–Function Relationships in the Human P-Glycoprotein (ABCB1): Insights from Molecular Dynamics Simulations

P-Glycoprotein (P-gp) is a transmembrane protein belonging to the ATP binding cassette superfamily of transporters, and it is a xenobiotic efflux pump that limits intracellular drug accumulation by pumping compounds out of cells. P-gp contributes to a reduction in toxicity, and has broad substrate specificity. It is involved in the failure of many cancer and antiviral chemotherapies due to the phenomenon of multidrug resistance (MDR), in which the membrane transporter removes chemotherapeutic drugs from target cells. Understanding the details of the ligand–P-gp interaction is therefore critical for the development of drugs that can overcome the MDR phenomenon, for the early identification of P-gp substrates that will help us to obtain a more effective prediction of toxicity, and for the subsequent outdesign of substrate properties if needed. In this work, a series of molecular dynamics (MD) simulations of human P-gp (hP-gp) in an explicit membrane-and-water environment were performed to investigate the effects of binding different compounds on the conformational dynamics of P-gp. The results revealed significant differences in the behaviour of P-gp in the presence of active and non-active compounds within the binding pocket, as different patterns of movement were identified that could be correlated with conformational changes leading to the activation of the translocation mechanism. The predicted ligand–P-gp interactions are in good agreement with the available experimental data, as well as the estimation of the binding-free energies of the studied complexes, demonstrating the validity of the results derived from the MD simulations.     

Modulation of Transaminase Activity by Encapsulation in Temperature-Sensitive Poly(N-acryloyl glycinamide) Hydrogels

Smart hydrogels hold much potential for biocatalysis, not only for the immobilization of enzymes, but also for the control of enzyme activity. We investigated upper critical solution temperature-type poly N-acryloyl glycinamide (pNAGA) hydrogels as a smart matrix for the amine transaminase from Bacillus megaterium (BmTA). Physical entrapment of BmTA in pNAGA hydrogels results in high immobilization efficiency (>89 %) and high activity (97 %). The temperature-sensitiveness of pNAGA is preserved upon immobilization of BmTA and shows a gradual deswelling upon temperature reduction. While enzyme activity is mainly controlled by temperature, deactivation tended to be higher for immobilized BmTA (≈62–68 %) than for free BmTA (≈44 %), suggesting a deactivating effect due to deswelling of the pNAGA gel. Although the deactivation in response to hydrogel deswelling is not yet suitable for controlling enzyme activity sufficiently, it is nevertheless a good starting point for further optimization.     

ZnO-based single crystal-polycrystal structures for piezotronic applications

Electrostatic potential barriers at doped ZnO-ZnO interfaces can be modified by stress-induced polarization charges. This concept was enhanced by preparing ZnO-based single crystal-polycrystal-single crystal structures by diffusion bonding. Increasing time for epitaxial solid-state transformation results in structures with a decreasing thickness of residual polycrystalline material in between two well-oriented single crystals. Microstructural and electrical analysis quantifies the influence of high-temperature treatment during epitaxial growth on the stress sensitivity of the prepared structures. The orientation of the single crystals is defined to maximize the interaction between stress-induced polarization charges and the potential barriers at doped ZnO-ZnO interfaces. With decreasing thickness of residual polycrystalline material, the percentage of grain boundaries with favorably aligned polarization vectors is increased resulting in a higher stress sensitivity. This effect is compensated by an adverse effect of the high-temperature treatment on the initial potential barrier height. Hence, a maximum in stress sensitivity can be observed for intermediate times of epitaxial growth. The prepared structures close the gap between the varistor piezotronics based on bulk ceramics with random orientation of the polarization vector and the bicrystal piezotronics with perfect orientation of the polarization vector, demonstrating the capability of microstructural engineering for varistor-based piezotronic devices.