The polar cluster like behavior in Ti substituted BaZrO3 ceramics

In this paper we report the evolution of the polar cluster like behavior with the incorporation of Ti⁴⁺ ion in BaZrO₃ Ceramics. Dielectric behavior of BaZr_xTi_(1−x)O₃ (x = 1.00, 0.95, 0.90, 0.85) ceramics is studied in the temperature range from 300 to 30 K. Polar cluster like behavior becomes more prominent with the increase in content of Ti⁴⁺ ion. The dielectric relaxation is analyzed by Vogel–Fulcher relation and Arrhenius law. Frequency dependence of dielectric constant and low loss tangent of these materials can be useful for the potential applications at low temperature.     

Tribological Behavior of Aluminum Alloy AlSi10Mg-TiB<Subscript>2</Subscript> Composites Produced by Direct Metal Laser Sintering (DMLS)

Direct metal laser sintering (DMLS) is an additive manufacturing technique for the production of parts with complex geometry and it is especially appropriate for structural applications in aircraft and automotive industries. Aluminum-based metal matrix composites (MMCs) are promising materials for these applications because they are lightweight, ductile, and have a good strength-to-weight ratio This paper presents an investigation of microstructure, hardness, and tribological properties of AlSi10Mg alloy and AlSi10Mg alloy/TiB₂ composites prepared by DMLS. MMCs were realized with two different compositions: 10% wt. of microsize TiB₂, 1% wt. of nanosize TiB₂. Wear tests were performed using a pin-on-disk apparatus on the prepared samples. Performances of AlSi10Mg samples manufactured by DMLS were also compared with the results obtained on AlSi10Mg alloy samples made by casting. It was found that the composites displayed a lower coefficient of friction (COF), but in the case of microsize TiB₂ reinforcement the wear rate was higher than with nanosize reinforcements and aluminum alloy without reinforcement. AlSi10Mg obtained by DMLS showed a higher COF than AlSi10Mg obtained by casting, but the wear rate was higher in the latter case.     

Multi-objective Topology Optimization of Thermo-mechanical Compliant Mechanisms

The material characteristics of a structure will change with temperature variation,and will induce stress within the structure.Currently,the optimal design for the topology of compliant mechanisms is mainly performed in single physical field.However,when compliant mechanisms work in high temperature environments,their displacement outputs are generated not only by mechanical load,but also by the temperature variation which may become the prominent factor.Therefore,the influence of temperature must be considered in the design.In this paper,a novel optimization method for multi-objective topology of thermo-mechanical compliant mechanisms is presented.First,the thermal field is analyzed with finite-element method,where the thermal strain is taken into account in the constitutive relation,and the equivalent nodal thermal load is derived with the principle of virtual work.Then the thermal load is converted into physical loads in elastic field,and the control equation of the thermo-mechanical compliant mechanism is obtained.Second,the mathematical model of the multi-objective topology optimization is built by incorporating both the flexibility and stiffness.Meanwhile,the coupling sensitivity function and the sensitivity analysis equations of thermal steady-state response are derived.Finally,optimality criteria algorithm is employed to obtain numerical solution of the multi-objective topology optimization.Numerical examples show that the compliant mechanisms have better performance and are more applicable if the temperature effect is taken into account in the design process.The presented modeling and analysis methods provide a new idea and an effective approach to topology optimization of compliant mechanisms in electrothermic coupling field and multiphysics fields.     

Klippel-Trenaunay syndrome

The Klippel-Trenaunay syndrome is a rare congenital pathology which includes varices, hemangiomas and hypertrophy of limbs. The Authors report two cases and pay particular attention to the diagnostic and therapeutical protocols. Although these aspects are still open questions, the Authors conclude that conservative therapy is often sufficient while surgery is requested only in the severe forms.     

Discrepant social communications.

Observed 32 children (13–42 mo old) individually in the presence of their mothers. Eight messages systematically varied between the visual and auditory channels were given by the experimenter. Some messages asked S to approach; other messages asked S to stay away. Some were congruent and others discrepant across channels. Order of presentation was counterbalanced across Ss. All Ss approached the experimenter when he unambiguously invited them with a smiling face, affirmative head nods, manual beckoning, and a pleasant tone of voice, saying, "Come here." When the experimenter's request to approach or to stay away was on one channel only, that is, was either visual or auditory, about three-fourths of the Ss conformed to it, approaching or staying away as requested. When requests were discrepant across channels, behavior was more variable, but more Ss conformed to the auditory than to the visual message. The messages constitute a Guttman scale, a unidimensional and cumulative hierarchy based on the individual patterns of responses to them. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis, biological activity, and ADME properties of novel S-DABOs/N-DABOs as HIV reverse transcriptase inhibitors

Previous studies aimed at exploring the SAR of C2-functionalized S-DABOs demonstrated that the substituent at this position plays a key role in the inhibition of both wild-type RT and drug-resistant enzymes, particularly the K103N mutant form. The introduction of a cyclopropyl group led us to the discovery of a potent inhibitor with picomolar activity against wild-type RT and nanomolar activity against many key mutant forms such as K103N. Despite its excellent antiviral profile, this compound suffers from a suboptimal ADME profile typical of many S-DABO analogues, but it could, however, represent a promising candidate as an anti-HIV microbicide. In the present work, a new series of S-DABO/N-DABO derivatives were synthesized to obtain additional SAR information on the C2-position and in particular to improve ADME properties while maintaining a good activity profile against HIV-1 RT. In vitro ADME properties (PAMPA permeation, water solubility, and metabolic stability) were also experimentally evaluated for the most interesting compounds to obtain a reliable indication of their plasma levels after oral administration.     

Toward the discovery of novel anti-HIV drugs. Second-generation inhibitors of the cellular ATPase DDX3 with improved anti-HIV activity: synthesis, structure-activity relationship analysis, cytotoxicity studies, and target validation

A hit optimization protocol applied to the first nonnucleoside inhibitor of the ATPase activity of human DEAD-box RNA helicase DDX3 led to the design and synthesis of second-generation rhodanine derivatives with better inhibitory activity toward cellular DDX3 and HIV-1 replication. Additional DDX3 inhibitors were identified among triazine compounds. Biological data were rationalized in terms of structure-activity relationships and docking simulations. Antiviral activity and cytotoxicity of selected DDX3 inhibitors are reported and discussed. A thorough analysis confirmed human DDX3 as a valid anti-HIV target. The compounds described herein represent a significant advance in the pursuit of novel drugs that target HIV-1 host cofactors.     

A correction to the unimodal and bimodal truncated normal distributions for a more accurate representation of extreme and calm wind speeds

The use of wind speed probability density functions is a standard practice to represent different wind regimes. Generally, these regimes are distinguished by the following three characteristics: the shape of the distribution in the central wind speeds, amount of the calm wind speeds (CWS), and extreme wind speeds (EWS). An in‐depth review has highlighted that none of the parametric distributions available is suitable to represent the three main characteristics at the same time. To overcome this gap, the use of the corrected mixture of two truncated normal distributions (CMTTND) and corrected single truncated normal distribution (CTND) are proposed to represent, respectively, bimodal and unimodal wind speed distribution shapes. The CMTTND and CTND are obtained by introducing a correction, respectively, to the mixture of two truncated normal distributions (MTTND) and to the single truncated normal distribution (TND). The MTTND and TND permit an accurate representation of distributions with high levels of CWS. The CMTTND and CTND employ a new parameter, to accurately quantifying also the relative frequencies associated with EWS. The performance of the CMTTND and CTND was assessed using a goodness‐of‐fit (GOF) test and statistical measures of error in the evaluation of the characteristic mean wind speeds. The analytical expressions of these mean wind speeds are obtained and validated by a numerical integration method for the first time in this work. The accuracy of these distributions is compared with that of other conventional probability distribution models, of which three are unimodal and six bimodal, in four Italian locations and three American locations. The analysis of the results showed that the CTND and CMTTND allow obtaining high GOF of the experimental distributions with R² and RMSE higher and lower than, respectively, 0.977 and 0.054. Moreover, the CTND results in the most accurate distribution in the estimation of the characteristic mean wind speeds in the case of localities with unimodal experimental distributions and the CMTTND in the case of localities with bimodal experimental distributions. Contrary to other distribution, CTND and CMTTND accuracies grow by increasing the grade of the characteristic mean wind speed by reaching also estimation values lower than 2% of the real ones. This is a great advantage in the wind energy source determination in a location since the available energy depends on the mean cubic wind speed.     

Bilateral adrenal pheochromocytoma. A clinical case and review of the literature

The authors present a case of bilateral adrenal pheochromocytoma that occurred at their observation and surgically treated with a bilateral adrenalectomy. The authors review the literature in order to discuss the diagnostic and therapeutic option to treat these cases. They stress the importance of preoperative abdominal TC an MIBG scintigraphy and the importance of pre and intraoperative assessment to exclude extra adrenal localization of pheochromocytoma.