Teobromin ve Teobromin-Su Bileşikleri Üzerine Deneysel ve Teorik Çalışmalar

In this study, the solvent effects on structural, spectroscopic, electronic and thermochemical properties of Theobromine (tbH) were theoretically investigated. The dichloromethane (DCM), dimethylsulfoxide (DMSO) and water (H2O) solvents have been chosen for investigations. Optimized molecular structures of tbH were obtained by using the DFT/B3LYP method with 6-311++G(d,p) basis set in vacuum and in solvent media. Calculated geometric structure parameters were compared with experimental data. In the experimental section, the mid-IR spectrum of tbH was recorded using ATR equipment and compared with calculated vibrational frequencies. tbH-H2O complexes were studied for various binding ratios. The total energies and hydrogen bond lengths of these complexes were discussed in detail. It is seen as the result of this study that N⋯H-O and O⋯H-O non-covalent bonded structures are more stable for all binding versions and hydrogen bond lengths for all tbH-H2O complexes range from 1.8-2.5 Å.Bu çalışmada Teobromin’in (tbH) yapısal, spektroskopik, elektronik ve termokimyasal özellikleri üzerine çözücü etkileri teorik olarak incelenmiştir. İncelemelerde, diklorometan (DCM),dimetilsülfoksit (DMSO) ve su (H2O) çözücüleri seçilmiştir. tbH’nin optimize edilmiş moleküler yapıları, DFT/B3LYP metodu ve 6- 311++G(d,p) temel seti kullanılarak vakum ve çözücü ortamlarda elde edilmiştir. Çalışmanın deneysel kısmında, tbH orta-bölge IR spektrumu, ATR sistemi ile kaydedilmiş ve deneysel sonuçlar hesaplanan verilerle kıyaslanmıştır. Farklı bağlanma oranları için, tbH-H2O bileşikleri çalışılmıştır. Bileşiklerin toplam enerjileri ve hidrojen bağ uzunlukları detaylı bir şekilde incelenmiştir. Yapılan bu çalışmanın sonuçlarından N⋯H-O ve O⋯H-O tipi kovalent bağlı olmayan yapılar, diğer tüm bağlanma durumlarından daha kararlıdır ve bileşiklerin hidrojen bağ uzunlukları 1.8-2.5 Å aralığında değişmektedir

Optimization of a robust reinforcement learning policy

A major challenge for the integration of unmanned air vehicle (UAV) in the current civil applications is the sense-and-avoid (SAA) capability and the consequent possibility of mid-air collision avoidance. Although UAS have been shown to be efficient under different and varied conditions, their safety, reliability, and compliance with aviation regulations remain to be proven. In autonomous collision avoidance, UAS sense hazards with the sensors equipped on them and make decisions on manoeuvres autonomously for collision avoidance at the minimum safe time before impact. Thus, it is required for each individual UAS to have capabilities to recognize urgent threats and undertake the evasive manoeuvres immediately. Most of the current sense and avoid algorithms are composed of separated obstacle detection and tracking algorithm and decision-making algorithm on avoidance manoeuvre. Implementing artificial intelligence (AI), reinforcement learning (RL) algorithm combines both sense and avoid functions through state and action space. An autonomous agent learns to perform complex tasks by maximizing reward signals while interacting with its environment. It may be infeasible to test a policy in all contexts since it is difficult to ensure it works as broadly as intended. In these cases, it is important to trade-off between performance and robustness while learning a policy. This work develops an optimization method for a robust reinforcement learning policy for a nonlinear small unmanned air systems (sUAS), in AirSim using a model-free architecture. Using an on-line trained reinforcement learning agent, the difference of an optimized robust reinforcement learning (RRL) policy together with a conventional RL and RRL algorithm will be reproduced.Engineering and Physical Sciences Research Council (EPSRC): 2454266 Thales U

Impact of maternal obesity and diabetes on long-term health of the offspring.

The initial observations of David Barker, popularly known as the “Barker hypothesis” or “developmental origins of health and disease,” show that being born with low birth weight, as a result of intrauterine growth restriction produced by maternal undernutrition, is associated with a number of chronic diseases later in life [1]. Subsequently, studies show that it is not just intrauterine growth restriction, but also exposure to any other adverse factor during fetal and/or early postnatal development that can increase susceptibility to a number of chronic diseases later in life including cardiovascular and renal disease, hypertension, type 2 diabetes, certain forms of cancer, osteoporosis, Parkinson’s disease, dementia, and polycystic ovary syndrome [2–4

Detect and avoid considerations for safe sUAS operations in urban environments

Operations involving small Unmanned Aerial Systems (sUAS) in urban environments are occurring ever more frequently as recognized applications gain acceptance, and new use cases emerge, such as urban air mobility, medical deliveries, and support of emergency services. Higher demands in these operations and the requirement to access urban airspace present new challenges in sUAS operational safety. The presence of Detect and Avoid (DAA) capability of sUAS is one of the major requirements to its safe operation in urban environments according to the current legislation, such as the CAP 722 in the United Kingdom (UK). The platform or its operator proves a full awareness of all potential obstacles within the mission, maintains a safe distance from other airspace users, and, ultimately, performs Collision Avoidance (CA) maneuvers to avoid imminent impacts. Different missions for the defined scenarios are designed and performed within the simulation model in Software Tool Kit (STK) software environment, covering a wide range of practical cases. The acquired data supports assessment of feasibility and requirements to real-time processing. Analysis of the findings and simulation results leads to a holistic approach to implementation of sUAS operations in urban environments, focusing on extracting critical DAA capability for safe mission completion. The proposed approach forms a valuable asset for safe operations validation, enabling better evaluation of risk mitigation for sUAS urban operations and safety-focused design of the sensor payload and algorithms

Effect of Co-60 gamma-ray irradiation on electrical properties of Ti/Au/GaAs1-xNx Schottky diodes

Current-voltage (I-V), capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G/ω-V-f) measurements at room temperature are used to study 50 kGy 60Co γ-ray electrical properties irradiation dependence of Ti/Au/GaAs1−xNx Schottky diodes with 0.2%; 0.4%; 0.8% and 1.2% nitrogen dilution. This γ-ray irradiation induces a permanent damage that has increased ideality factor and series resistance for all samples. It was accompanied by a decrease in Schottky barrier height with nitrogen content up to 0.4%N and remained constant thereafter. Radiation was also found to degrade the reverse leakage current. At high frequency (1 MHz), capacitance and conductance decreased after radiation due to a decrease in net doping concentration. Interface state density and series resistance were determined from C-V-f and G/ω-V-f characteristics using Hill-Coleman methods. Interface states density exponentially decreased with increasing frequency confirming the behavior of interface traps response to ac signal. Series resistance increases after irradiation is attributed to carrier's removal effect and mobility degradation. It has two peaks in the accumulation and inversion region for some diodes (0.4%N, 0.8%N). γ-ray irradiation produced traps levels and recombination centers that reduce relaxation time. An increase in %N content can impede irradiation damage with even some compensation when the percent of diluted nitrogen is high (1.2%N)

Reduced microvascular density in omental biopsies of children with chronic kidney disease

Endothelial dysfunction is an early manifestation of cardiovascular disease (CVD) and consistently observed in patients with chronic kidney disease (CKD). We hypothesized that CKD is associated with systemic damage to the microcirculation, preceding macrovascular pathology. To assess the degree of "uremic microangiopathy", we have measured microvascular density in biopsies of the omentum of children with CKD.Omental tissue was collected from 32 healthy children (0-18 years) undergoing elective abdominal surgery and from 23 age-matched cases with stage 5 CKD at the time of catheter insertion for initiation of peritoneal dialysis. Biopsies were analyzed by independent observers using either a manual or an automated imaging system for the assessment of microvascular density. Quantitative immunohistochemistry was performed for markers of autophagy and apoptosis, and for the abundance of the angiogenesis-regulating proteins VEGF-A, VEGF-R2, Angpt1 and Angpt2.Microvascular density was significantly reduced in uremic children compared to healthy controls, both by manual imaging with a digital microscope (median surface area 0.61% vs. 0.95%, p<0.0021 and by automated quantification (total microvascular surface area 0.89% vs. 1.17% p = 0.01). Density measured by manual imaging was significantly associated with age, height, weight and body surface area in CKD patients and healthy controls. In multivariate analysis, age and serum creatinine level were the only independent, significant predictors of microvascular density (r2 = 0.73). There was no immunohistochemical evidence for apoptosis or autophagy. Quantitative staining showed similar expression levels of the angiogenesis regulators VEGF-A, VEGF-receptor 2 and Angpt1 (p = 0.11), but Angpt2 was significantly lower in CKD children (p = 0.01).Microvascular density is profoundly reduced in omental biopsies of children with stage 5 CKD and associated with diminished Angpt2 signaling. Microvascular rarefaction could be an early systemic manifestation of CKD-induced cardiovascular disease

Renoprotective effects of atorvastatin in diabetic mice: downregulation of RhoA and upregulation of Akt/GSK3

Potential benefits of statins in the treatment of chronic kidney disease beyond lipid-lowering effects have been described. However, molecular mechanisms involved in renoprotective actions of statins have not been fully elucidated. We questioned whether statins influence development of diabetic nephropathy through reactive oxygen species, RhoA and Akt/GSK3 pathway, known to be important in renal pathology. Diabetic mice (db/db) and their control counterparts (db/+) were treated with atorvastatin (10 mg/Kg/day, p.o., for 2 weeks). Diabetes-associated renal injury was characterized by albuminuria (albumin:creatinine ratio, db/+: 3.2 ± 0.6 vs. db/db: 12.5 ± 3.1*; *P&lt;0.05), increased glomerular/mesangial surface area, and kidney hypertrophy. Renal injury was attenuated in atorvastatin-treated db/db mice. Increased ROS generation in the renal cortex of db/db mice was also inhibited by atorvastatin. ERK1/2 phosphorylation was increased in the renal cortex of db/db mice. Increased renal expression of Nox4 and proliferating cell nuclear antigen, observed in db/db mice, were abrogated by statin treatment. Atorvastatin also upregulated Akt/GSK3β phosphorylation in the renal cortex of db/db mice. Our findings suggest that atorvastatin attenuates diabetes-associated renal injury by reducing ROS generation, RhoA activity and normalizing Akt/GSK3β signaling pathways. The present study provides some new insights into molecular mechanisms whereby statins may protect against renal injury in diabetes

A comparative study on the electrical characterization of Al/p-Si (MS) structures with and without interfacial perylene (C2OH12) layer at room temperature

Bu çalışmada, Al/p-Si Schottky engel diyotun (D1) performansını artırmak amacıyla Al ile p-Si arasına ince bir perylene (C20H12) tabakası spin coating yöntemi ile büyütülerek Al/C20H12/p-Si tipi Schottky engel diyotu (D2) hazırlandı. Hazırlanan bu iki tip diyotun idealite faktörü (n), engel yüksekliği (?Bo ), seri direnç (Rs), kısa devre direnci (Rsh), ara yüzey durumları (Nss) ve tüketim tabasının genişliği (WD) gibi temel elektriksel parametreleri oda sıcaklığında elde edildi ve karşılaştırıldı. Bu karşılaştırma, doğru ve ters öngerilim altında, 1 MHz de, akım-voltaj (I-V), kapasitans-voltaj (C-V) ve kondüktans- voltaj (G/w) ölçümleri kullanılarak yapıldı. Elde edilen deneysel sonuçlar, tüm bu parametrelerin hem frekansa hem de arayüzey tabakasına oldukça bağlı olduğunu gösterdi. Al/p-Si diyotlarda doğrultma oranı (±3V da) 2,1x103 iken, Al/C20H12/p-Si diyotlarda ise 1,7x104 olarak bulundu. Aynı zamanda Al/C20H12/p-Si diyotunda kaçak akımının büyüklüğünün, Al/p-Si Schottky diyota göre 10 kat daha düşük olduğu görüldü. Benzer şekilde Ohm Yasası kullanılarak elde edilen Rs ve Rsh değerleri sırasıyla, doğru öngerilim ve ters öngerilim eğrilerinden, Al/C20H12/p-Si Schottky engel diyotu için 544?? ve 11M??, Al/p-Si Schottky engel diyotu için 716 ? ve 1,83 M? olarak bulundu. Bunlara ilave olarak Al/C20H12/p-Si ve Al/p-Si diyotlarının voltaja bağlı Nss dağılım profili düşük-yüksek frekans-kapasitans (CLF-CHF) metodu kullanılarak elde edildi. Al/C20H12/p-Si diyotu için Nss değerlerinin, Al/p-Si diyotu değerlerinden 2 kat daha düşük olduğu görüldü. Elde edilen bu deneysel sonuçlar ışığında, kullanılan perylene (C20H12) arayüzey polimer tabakasının, Schottky diyotunun performansını oldukça iyileştirdiği görülmektedir.Perylene (C20H12) thin interfacial layer was deposited on p-Si using spin coating system to improve the performance of Al/p-Si Schottky barrier diode (SBD). In order to compare with and without perylene SBD Al/C20H12/p-Si and Al/p-Si type diodes were fabricated and they called as D2 and D1 respectively. The main electrical parameters of D1 and D2 diodes, such as ideality factor (n), barrier height (?B), series resistance (Rs), shunt resistance (Rsh), voltage dependent density distribution profile of interface states (Nss) and depletion layer width (WD) were obtained from the forward bias current-voltage (I-V) and admittance spectroscopy methods (capacitance-voltage (C-V) and conductance-voltage (G/w-V) measurements) at room temperature. Experimental results show that the rectifying ratio of Al/p-Si type SBD is 2,1x103 while with C20H12 type SBD is 1,7x104 at (± 3 V). Also, the leakage current was found very sensitive to the C20H12 and the magnitude of the leakage current of perylene based diode is almost one order lower than that of MS or D1 diode. Similarly, the values of Rs and Rsh were obtained from the forward bias I-V data using Ohm?s Law and they found as 716 ? and 1,83 M??for the MS-type SBD and 544 ? and 11 M??for the MPS-type SBD. In addition, the voltage dependent density distribution profile of Nss of the MS and MPS type SBDs were obtained by the low-high frequency capacitance (CLF-CHF) method and the obtained mean value of Nss for MPS SBD is two times lower than that for MS SBD. These results show that the performance of the MS type SBD can be improved by using with a thin interfacial C20H12 polymer layer between metal and semiconductor