Effect of Fe2O3 doping on the electrical properties of a SnO2 based varistor

The effect of Fe₂O₃ addition on the densification and electrical properties of the (0.9895 – x) SnO₂ + 0.01CoO + 0.005Nb₂O₅ + xFe₂O₃ system, where x = 0.005 or 0.01, was considered in this study. The samples were sintered at 1300°C for 2 h. Microstructure analysis by scanning electron microscopy showed that the effect of Fe₂O₃ addition is to decrease the SnO₂ grain size. J × E curves indicated that the system exhibit a varistor behavior and the effect of Fe₂O₃ is to increase both, the non-linear coefficient () and the breakdown voltage (E _r ). Considering the Schottky thermionic emission model the potential height and width were estimated. Small amount addition of Fe₂O₃ to the basic system increases both the potential barrier height and width.     

Intracardiac ultrasound scanner using a micromachine (MEMS) actuator

Catheter-based intracardiac ultrasound offers the potential for improved guidance of interventional cardiac procedures. The objective of this research is the development of catheter-based mechanical sector scanners incorporating high frequency ultrasound transducers operating at frequencies up to 20 MHz. The authors' current transducer assembly consists of a single 1.75 mm by 1.75 mm, 20 MHz, PZT element mounted on a 2 mm by 2 mm square, 75 mum thick polyimide table that pivots on 3-mum thick gold plated polyimide hinges. The hinges also serve as the electrical connections to the transducer. This table-mounted transducer is tilted using a miniature linear actuator to produce a sector scan. This linear actuator is an integrated force array (IFA), which is an example of a micromachine, i.e., a microelectromechanical system (MEMS). The IFA is a thin (2.2 mum) polyimide membrane, which consists of a network of hundreds of thousands of micron scale deformable capacitors made from pairs of metallized polyimide plates. IFAs contract with an applied voltage of 30-120 V and have been shown to produce strains as large as 20% and forces of up to 8 dynes. The prototype transducer and actuator assembly was fabricated and interfaced with a GagePCI analog to digital conversion board digitizing 12 bit samples at a rate of 100 MSamples/second housed in a personal computer to create a single channel ultrasound scanner. The deflection of the table transducer in a low viscosity insulating fluid (HFE 7100, 3M) is up to +/-10 degrees at scan rates of 10-60 Hz. Software has been developed to produce real-time sector scans on the PC monitor.     

Sickness presenteeism: measurement and management challenges

Since work can be restorative to health, attending work when unwell should not be viewed as an inherently negative phenomenon. However, the functional benefits are likely to depend on the health condition, and the psychosocial quality of the work provided. The current study used a workforce survey to explore differences in the pattern of presenteeism and absenteeism by health condition, the association of psychosocial work factors with presenteeism compared to absenteeism, and their interaction to predict health. Findings indicate that instead of substituting absenteeism for presenteeism, the two tend to coincide, but the balance differs by health condition. Presenteeism is more likely to occur in poorer psychosocial environments, reinforcing the importance of ensuring work is designed and managed in ways that are beneficial rather than detrimental to health. The findings also highlight the methodological importance of differentiating between the act and impact of presenteeism in future research and practice.

Practitioner Summary: Effective management of work-related health requires that practitioners manage both sickness absence and presence together, since employees tend to fluctuate between the two when unwell. Interventions should be tailored to the specific health concern, paying particular attention to the psychosocial environment in enabling employees to continue working without exacerbating health.     

Varistor behavior of the system SnO2ċCoOċTa2O5ċCr2O3

In this work the system (98.95–x)% SnO2+1%CoO+0.05%Ta2O5+x%Cr2O3 (mol %) was studied, with x=0.05 and 0.10, prepared by the conventional method of oxides mixture, and sintered at 1300 and 1350 °C for 2 h. The non-linear J versus E electrical characteristics (=25) were obtained in the Ta₂O₅ and Cr₂O₃–CoO doped highly densified SnO₂ ceramics. X-ray diffraction analysis showed that these ceramics are apparently single phase. Electrical properties and microstructure are highly dependent on the Cr₂O₃ concentration and on the sintering temperature. Excess of Cr₂O₃ leads to porous ceramics destroying the electrical characteristics of the material. Dopant solid solution formation in the SnO₂ may be responsible for the formation of electrical barriers in the grain boundaries.     

Diet and Male Fertility: The Impact of Nutrients and Antioxidants on Sperm Energetic Metabolism

Diet might affect male reproductive potential, but the biochemical mechanisms involved in the modulation of sperm quality remain poorly understood. While a Western diet is considered a risk factor for male infertility, the Mediterranean diet seems to protect against male infertility; moreover, the role of a vegetarian habitus in the preservation of sperm quality is controversial. The aim of this review is to analyze the molecular effects of single nutrients on sperm quality, focusing on their involvement in biochemical mechanisms related to sperm bioenergetics. It appears that diets rich in saturated fatty acids (SFA) and low in polyunsaturated fatty acids (PUFA) negatively affect sperm quality, whereas unsaturated fatty acids supplementation ameliorates sperm quality. In fact, the administration of PUFA, especially omega-3 PUFA, determined an increase in mitochondrial energetic metabolism and a reduction in oxidative damage. Carbohydrates and proteins are also nutritional modulators of oxidative stress and testosterone levels, which are strictly linked to sperm mitochondrial function, a key element for sperm quality. Moreover, many dietary natural polyphenols differentially affect (positively or negatively) the mitochondrial function, depending on their concentration. We believe that an understanding of the biochemical mechanisms responsible for sperm quality will lead to more targeted and effective therapeutics for male infertility.     

Vesicular Glutamate Release from Feeder-FreehiPSC-Derived Neurons

Human-induced pluripotent stem cells (hiPSCs) represent one of the main and powerful tools for the in vitro modeling of neurological diseases. Standard hiPSC-based protocols make use of animal-derived feeder systems to better support the neuronal differentiation process. Despite their efficiency, such protocols may not be appropriate to dissect neuronal specific properties or to avoid interspecies contaminations, hindering their future translation into clinical and drug discovery approaches. In this work, we focused on the optimization of a reproducible protocol in feeder-free conditions able to generate functional glutamatergic neurons. This protocol is based on a generation of neuroprecursor cells differentiated into human neurons with the administration in the culture medium of specific neurotrophins in a Geltrex-coated substrate. We confirmed the efficiency of this protocol through molecular analysis (upregulation of neuronal markers and neurotransmitter receptors assessed by gene expression profiling and expression of the neuronal markers at the protein level), morphological analysis, and immunfluorescence detection of pre-synaptic and post-synaptic markers at synaptic boutons. The hiPSC-derived neurons acquired Ca²⁺-dependent glutamate release properties as a hallmark of neuronal maturation. In conclusion, our study describes a new methodological approach to achieve feeder-free neuronal differentiation from hiPSC and adds a new tool for functional characterization of hiPSC-derived neurons.     

Neuroprotection and Neuroregeneration Strategies Using the rNAION Model: Theory,Histology, Problems,Results and Analytical Approaches

Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common cause of sudden optic nerve (ON)-related vision loss in humans. Study of this disease has been limited by the lack of available tissue and difficulties in evaluating both treatments and the window of effectiveness after symptom onset. The rodent nonarteritic anterior ischemic optic neuropathy model (rNAION) closely resembles clinical NAION in its pathophysiological changes and physiological responses. The rNAION model enables analysis of the specific responses to sudden ischemic axonopathy and effectiveness of potential treatments. However, there are anatomic and genetic differences between human and rodent ON, and the inducing factors for the disease and the model are different. These variables can result in marked differences in lesion development between the two species, as well as in the possible responses to various treatments. These caveats are discussed in the current article, as well as some of the species-associated differences that may be related to ischemic lesion severity and responses.     

Atopy and intolerance of antimicrobial drugs increase the risk of reactions to acetaminophen and nimesulide in patients allergic to nonsteroidal anti-inflammatory drugs

This study evaluated the risk factors for developing allergic reactions to alternative drugs such as acetaminophen and nimesulide in 367 patients intolerant of nonsteroidal anti-inflammatory drugs (NSAID) compared to 243 healthy controls. All subjects were given test doses (TD) of acetaminophen and nimesulide, and age, sex, atopy, and history of reactions also to unrelated drugs were compared in those who reacted and those who were tolerant of the challenge. TD was positive in 49 of 367 (14%) NSAID-allergic patients and in one (0.4%) of the controls (P<0.001). No difference was found in age and sex between the TD-positive and TD-negative subjects, although a significantly larger number of females were NSAID allergic (P<0.01). Of the 367 patients, 208 had a history of reactions only to NSAID, and 148 to NSAID and antimicrobial drugs (AMD). TD with acetaminophen or nimesulide was positive in 6% of patients intolerant only of NSAID and in 24% of those intolerant of both NSAID and AMD, with an odds ratio of 4.82. Atopy was more frequent among patients (36%) than controls (23%) (P=0.004), among TD-positive (51%) than TD-negative patients (33.5%) (P<0.02), and among patients intolerant of NSAID and AMD (48%) than those intolerant only of NSAID (P=0.006). The odds ratios were, respectively, 1.87, 2.57, and 3.16. This study provides evidence that atopy and history of allergic reactions to AMD increase the likelihood of intolerance of usually well-tolerated alternative drugs such as acetaminophen and nimesulide in subjects allergic to NSAID.