Newly Synthesized Nonvacuum Processed High-k Polymeric Dielectrics with Carboxyl Functionality for Highly Stable Operating Printed Transistor Applications

Solution-processed polar hydroxyl containing polymers such as poly(4-vinylphenol) are widely utilized in organic filed-effect transistors (OFETs) due to their high dielectric constant (k) and excellent insulating properties owing to the crosslinking through their hydroxyl groups. However, hydroxyl functionalities can function as trapsites, and their crosslinking reactions decrease the k value of materials. Hence, in this study, new solution-processable copolymers containing both carboxyl and hydrophobic functionalities are synthesized. A fluorophenyl azide (FPA) based UV-assisted crosslinker is also employed to promote the movement of polar carboxyl groups toward the bulk region and the hydrophobic functionalities to the surface region, thereby maintaining the high-k characteristics and hydrophobic surface in thin film. Thus, the addition of an FPA crosslinker eliminates the trapsites on the surface, allowing a stable operation and efficient charge transport. Additionally, the solution-processability enables the production of uniform and thin films to yield OFETs with stable and low-voltage driving characteristics. The printed layers are also applied as gate dielectrics for floating gate memory devices and in integrated one-transistor-one-transistor based memory cells, displaying their excellent memory performance. The synthesis and fabrication strategies employed in this study can become useful guidelines for the production of high-k dielectrics for stable OFETs and other applications.     

Nonlinear Bayesian Estimation: From Kalman Filtering to a Broader Horizon

This article presents an up-to-date tutorial review of nonlinear Bayesian estimation. State estimation for nonlinear systems has been a challenge encountered in a wide range of engineering fields, attracting decades of research effort. To date, one of the most promising and popular approaches is to view and address the problem from a Bayesian probabilistic perspective, which enables estimation of the unknown state variables by tracking their probabilistic distribution or statistics (e.g., mean and covariance) conditioned on a system's measurement data. This article offers a systematic introduction to the Bayesian state estimation framework and reviews various Kalman filtering (KF) techniques, progressively from the standard KF for linear systems to extended KF, unscented KF and ensemble KF for nonlinear systems. It also overviews other prominent or emerging Bayesian estimation methods including Gaussian filtering, Gaussian-sum filtering, particle filtering and moving horizon estimation and extends the discussion of state estimation to more complicated problems such as simultaneous state and parameter/input estimation.      

Phosphonates of Vegetable Oils—Characterization as Lubricants

Dialkyl phosphonates of vegetable oils were synthesized by reacting soybean (Soy) and high oleic sunflower (HOSuO) oils with dialkyl phosphites. Dimethyl, diethyl, and di-n-butyl phosphites were used in the synthesis and the resulting phosphonates were obtained in good yields and thoroughly characterized. All six phosphonates displayed poor solubility in polyalphaolefin-6; and four displayed adequate solubility (> 20% w/w) in HOSuO. Evaluation as anti-wear (AW) additives in HOSuO base oil blends showed the biobased phosphonates have similar coefficient of friction and similar or better wear scar diameter than zinc dialkyl dithio phosphates (ZDDP). It is concluded that vegetable oil phosphonates provide a promising biobased alternative to ZDDP and other commercial petroleum-based AW additives currently used in lubricant formulations.     

Optimal cut-off for obesity and markers of metabolic syndrome for Ethiopian adults

Background

Metabolic syndrome (MetS) is defined as the presence of central obesity plus any two of the following markers: high triglycerides (>?150 mg/dl), low high density lipoprotein (HDL) cholesterol <?40 mg/dl in men and?<?50 mg/dl in women, hypertension (blood pressure?>?130/85 mmHg or use of antihypertensive medication), high fasting blood glucose (>?100 mg/dl or use of treatment for diabetes mellitus). Since recently, metabolic syndrome and obesity have become emerging problems of both low and middle income countries, although they have been the leading cause of morbidity and mortality in high income countries for the past decades. It has been indicated that the international anthropometric cut-off for detecting obesity is not appropriate for Ethiopians. This study developed optimal cut off values for anthropometric indicators of obesity and markers of metabolic syndrome for Ethiopian adults to enhance preventive interventions.

Methods

A total of 704 employees of Jimma University were randomly selected using their payroll as a sampling frame. Data on socio-demographic, anthropometry, clinical and blood samples were collected from February to April 2015. Receiver Operating Characteristic Curve analyses were used to determine optimal anthropometric cut-off values for obesity and markers of the metabolic syndrome. WHO indicators of obesity based on body fat percent (>?25% for males and?>?35% for females) were used as binary classifiers for developing anthropometric cut-offs. Optimal cut-off values were presented using sensitivity, specificity and area under the curve.

Results

The optimal cut-off for obesity using body mass index was 22.2 k/m² for males and 24.5 kg/m² for females. Similarly, the optimal waist circumference cut-off for obesity was 83.7 cm for males and 78.0 cm for females. The cut-off values for detecting obesity using waist to hip ratio and waist to height ratio were: WHR (0.88) and WHtR (0.49) for males, while they were 0.82 and 0.50 for females, respectively. Anthropometric cut-off values for markers of metabolic syndrome were lower compared to the international values. For females, the optimal BMI cut-offs for metabolic syndrome markers ranged from 24.8 kg/m² (triglycerides) to 26.8 kg/m² (fasting blood sugar). For WC the optimal cut-off ranged from of 82.1 cm (triglyceride) to 96.0 cm(HDL); while for WHtR the optimal values varied from 0.47(HDL) to 0.56(fasting blood sugar). Likewise, the optimal cut-offs of WHR for markers of metabolic syndrome ranged from 0.78(fasting blood sugar) to 0.89(HDL and blood pressure). For males, the optimal BMI cut-offs for metabolic syndrome markers ranged from 21.0 kg/m² (HDL) to 23.5 kg/m² (blood pressure). For WC, the optimal cut-off ranged from 85.3 cm (triglyceride) to 96.0 cm(fasting blood sugar); while for WHtR the optimal values varied from 0.47(BP, FBS and HDL) to 0.53(Triglyceride). Similarly, the optimal cut-offs of WHR form markers of metabolic syndrome ranged from 0.86(blood pressure) to 0.95(fasting blood sugar).

Conclusion

The optimal anthropometric cut-offs for obesity and markers of metabolic syndrome in Ethiopian adults are lower than the international values. The findings imply that the international cut-off for WC, WHtR, WHR and BMI underestimate obesity and metabolic syndrome markers among Ethiopian adults, which should be considered in developing intervention strategies. It is recommended to use the new cut-offs for public health interventions to curb the increasing magnitude of obesity and associated metabolic syndrome and diet related non-communicable diseases in Ethiopia.

     

High‐temperature structural stability of ceria‐based inverse opals

The use of ceria‐based inverse opals as a catalyst system for the thermochemical production of fuels from sunlight offers the potential of improved fuel production kinetics over materials with random porosity. Quantitative methods for characterizing ordered porosity are lacking, thus limiting the ability to predict the lifetime of ordered structures at elevated temperatures. In the present work, Fourier transform image analysis was used to determine the effect of composition and temperature on ordered porosity for a series of CeO₂‐ZrO₂ inverse opals having pore sizes ranging from 300 nm to 1 μm. An order parameter, γ, derived from the image analysis, was applied to scanning electron microscopy images and used to determine the degree of order in the inverse opal. The thermal stability studies indicate that loss of ordered porosity is highly dependent on temperature and that gas cycling effects have a minor effect on periodicity. A minimum Zr content of 20 at.% is necessary to retain periodicity for annealing up to 1000°C with pore diameters larger than 1 μm. These results show that CeO₂‐ZrO₂ inverse opals can be used at higher temperatures than previously thought for efficient thermochemical hydrogen production without loss of the benefits associated with ordered porosity.     

A piezomicrobalance system for high‐temperature mass relaxation characterization of metal oxides: A case study of Pr‐doped ceria

A system for mass relaxation studies based on a gallium phosphate piezocrystal microbalance has been developed, built, and successfully used to characterize a representative mixed ionic and electronic conducting material. The apparatus is constructed to achieve reactor gas exchange times as short as 2 seconds and temporal resolution in mass measurement of 0.1 seconds. These characteristics enabled evaluation of mass relaxations that occurred on the 6 seconds time scale. Proof of concept for materials characterization capabilities of the system was carried out using 10% praseodymium‐doped cerium oxide (PCO), a material that undergoes, at selected temperatures and oxygen partial pressures, changes in mass but not in conductivity. Thin films were deposited on the piezocrystals via pulsed laser deposition (PLD). Mass relaxation curves were collected at 700°C upon application of a small step change in oxygen partial pressure, . Using two different films, the surface reaction constant, k_S, was obtained over the range from 10^?4 to 0.1 atm. Its value is found to vary between 9.7 × 10^?6 and 1.7 × 10^?4 cm/s, displaying a power law dependence on , with a law exponent of 0.67 ± 0.02, as averaged over the two sets of results. This steep dependence of k_S on is surprisingly independent of a change in dominant defect type within the range of measurement.     

Conventional chiller performances simulation and field data

In most commercial buildings and industrial plants HVAC systems consume large amounts of energy, and usually offer the most significant potential for savings. Liquid conventional chillers play a very important role in providing these savings. Proper design, installation, and maintenance of these systems are therefore the key steps leading to improved efficiency which benefit both the customers and the utilities. To effectively materialize this concept two steps have been followed here. In the first section of this paper conventional chillers of different types have been modelled and simulated using a software (DOE2). The chillers are rated for a generic building and meteorological weather of San Diego. Performance parameters such as the part/full-load efficiencies, the number of occurrences during peak hours and load frequencies are then calculated. These results gave typical performance values (curves) which can be used to compare screw, centrifugal, and reciprocating chillers among each other within a predefined scope. In the following section the field data of 39 conventional chillers and the manufacturers specifications of some of them are collected and analysed. This gave an overall view of their actual field performance and their deviation from the manufacturers' specifications. Comparison of the simulated and collected data also provided better vision of the expected performances versus the actual performances, and pinpointed some major drawbacks in the design and sizing methodology. The results also led to important conclusions regarding the status quo and the possibilities in the immediate future. Preferred chiller types and methods of providing the required cooling energy recommended by the simulation results are compared with the existing ways of providing energy in order to conform the eventual promises and quantify the room for efficiency.     

Black-box modeling of passive systems by rational function approximation

In this paper, a rational interpolation approach is used to approximate the transfer function of passive systems characterized by sampled data. Orthogonal polynomials are used to improve the numerical stability of the ill-conditioned Vandermonde-like interpolation matrix associated with the ordinary power series. First, the poles of the system are obtained by efficiently and accurately transforming the coefficients of the orthogonal polynomials to the ordinary power series using Clenshaw's recurrence algorithm. Then, the residues are solved in real or in complex conjugate pairs to insure a physically realizable system. Finally, the passivity of the system is enforced by applying certain constraints on the poles and residues of the system. The performances of the three most common orthogonal polynomials, Legendre and Chebyshev of the first and second kinds, are also compared to that of the power series.     

A clinical trial of antioxidant vitamins to prevent colorectal adenoma. Polyp Prevention Study Group

BACKGROUND: People who consume a diet high in vegetables and fruits have a lower risk of cancer of the large bowel. Antioxidant vitamins, which are present in vegetables and fruits, have been associated with a diminished risk of cancers at various anatomical sites. We conducted a randomized, controlled clinical trial to test the efficacy of beta carotene and vitamins C and E in preventing colorectal adenoma, a precursor of invasive cancer. METHODS: We randomly assigned 864 patients, using a two-by-two factorial design, to four treatment groups, which received placebo; beta carotene (25 mg daily); vitamin C (1 g daily) and vitamin E (400 mg daily); or the beta carotene plus vitamins C and E. In order to identify new adenomas, we performed complete colonoscopic examinations in the patients one year and four years after they entered the study. The primary end points for analyses were new adenomas identified after the first of these two follow-up examinations. RESULTS: Patients adhered well to the prescribed regimen, and 751 completed the four-year clinical trial. There was no evidence that either beta carotene or vitamins C and E reduced the incidence of adenomas; the relative risk for beta carotene was 1.01 (95 percent confidence interval, 0.85 to 1.20); for vitamins C and E, it was 1.08 (95 percent confidence interval, 0.91 to 1.29). Neither treatment appeared to be effective in any subgroup of patients or in the prevention of any subtype of polyp defined by size or location. CONCLUSIONS: The lack of efficacy of these vitamins argues against the use of supplemental beta carotene and vitamins C and E to prevent colorectal cancer. Although our data do not prove definitively that these antioxidants have no anticancer effect, other dietary factors may make more important contributions to the reduction in the risk of cancer associated with a diet high in vegetables and fruits.     

Integrative cognitive therapy for depression: A randomized pilot comparison.

This pilot study examined the efficacy of an integrative form of cognitive therapy (ICT) for depression that incorporates specific strategies for addressing alliance ruptures. Although a previous study on depression found that ICT was superior to a wait-list condition (L. G. Castonguay et al., 2004), the current study provides the 1st direct comparison between ICT and traditional cognitive therapy (CT). Twenty-two depressed adults were randomly assigned to ICT or CT (11 patients per condition), which were delivered by clinicians in training. Outcome was assessed with a specific depression measure and a global symptomatology measure. The groups were also compared on patient-perceived alliance quality and therapist empathy. Effect size estimates revealed that ICT patients evidenced greater posttreatment improvement on both outcome measures (with small to medium effects) and more clinically significant change than did CT patients. ICT patients also had higher alliance and empathy scores across treatment (with medium to large effects). The findings, albeit very preliminary, support the potential viability of ICT and the potential causal influence of the rupture-repair interventions on treatment process and outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved)