465 research outputs found
AC-Impedance, Dynamic mechanical analysis and DSC investigations on poly(methyl methacrylate)–LiTf polymer electrolyte systems
Gel polymer electrolytes synthesized from Poly(methylmethacrylate) (PMMA) as the host, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer and LiCF3SO3 (LiTf) as a salt has been prepared using solution casting technique. X-ray characterization confirms the complete dissociation of the LiTf salt in the gel polymer. The effect of LiTf salt on ionic conductivity, ionic transference number (tion) and mechanical characteristics were investigated. The ac impedance has been studied to evaluate the ionic conductivity. It was observed that the ionic conductivity of the prepared gel reached the highest value of 6.60 x 10-5 S/cm at 10.2 wt.% (1M) of LiTf salt. The temperature dependence studies showed that the samples were ionic conductors and seemed to obey the Vogel Tamman Fulcher (VTF) rule. Dynamic mechanical analysis (DMA) indicates that the LiTf salt induces a remarkable increase in the storage modulus of the matrix at temperatures above the glass transition (rubbery plateau region)
The Properties of L-moments Compared to Conventional Moments
In this thesis, we survey the concept of L-moments. We introduce the deflnition of L-moments and the probability weighted moments (PWMs) and then we expressed the L-moments by the use of the probability weighted moments. Also, we established the relation between the L-moments and the order statistic. Moreover, we introduced some of the properties the L-moments especially the property that, if the mean of the distribution exists, then all of the L-moments exist and uniquely deflne the distribution. That is, no two distinct distributions have the same L-moments. This property is not always valid in the conventional moments. Moreover, we flnd the L-moments for some distributions. Later, we introduce estimation for the L-moments and probability weighted moments and then we used them in estimating the parameters of some distributions as the Uniform distribution, the Exponential distribution, Generalized Logistic distribution and Generalized Pareto Distribution. Moreover, we introduce the generalized lambda distribution (GLD) and we flnd the (PWMs) and L-moments for (GLD). Also, we deflned the Censored Data which is divided into two cases: I-Right censoring and II-Left censoring and then we flnd the partial property weighted moments (PPWMs) for both cases. Finally, we flnd the type B PPWMs for GLD
Design of Robust Digital Pole Placer for Car Active Suspension with Input Constraint
This chapter deals with the problem of state feedback control for an active quarter-car suspension system with control input constraint. The dynamics of the suspension system is first formed in terms of the control objectives: ride comfort, suspension deflection, and maximum actuator control force. The control task is formulated as robustly placing the closed poles in a desired region against different passenger load. Since digital computers are widely used in the vehicle industry, a new saturated controller design method is presented for regional pole-placement of uncertain discrete time systems. The constraint of control input saturation is considered in the design phase. The desired dynamic performance for uncertain discrete-time systems is represented by the settling time and damping ratio. A sufficient condition is derived to place the poles in a desired region. The design is formulated in terms of linear matrix inequality optimization. The effectiveness of the proposed design is illustrated by applying it to a quarter?car active suspension system. Different road tests for the proposed controller are carried out: step and bump disturbances. The proposed design achieves the desired oscillation damping due to road disturbances in addition to passenger comfort. The results are compared with the passive suspension system
Chromosomal study in newborn infants with congenital anomalies in Assiut University hospital: Cross-sectional study
In 40–60% of congenital malformations, the cause is unknown. Genetic factors account for approximately 15%; environmental factors produce approximately 10%; a combination of genetic and environmental influences produces 20–25%. The study aims to document prevalenceand patterns of congenital malformations detected at birth in Assiut University hospital and clarify underlying chromosomal abnormalities of such malformations. Also possible predisposing factors will be studied.Newborns with apparent congenital anomalies were selected from 5000 newborn infants delivered consecutively at the department of Obstetrics and Gynecology within 7 months. Full maternal history, family history, perinatal history, pedigree construction as well as clinical examinations andinvestigations including karyotype were done. Congenital anomalies were found in 103 cases with a prevalence of 2.06% with male to female ratio of 1.7:1. Skeletal system anomalies had the highestfrequency (37.9%), followed in descending order by chromosomal abnormalities (27.2%), circulatory system anomalies (22.3%), central nervous system (CNS) anomalies (19.4%), genital organs anomalies (16.5%), gastrointestinal tract (GIT) anomalies (14.6%), eye and ear anomalies (8.7%), and lastly urinary system and others anomalies in 3.9% each. Breech presentation, perinatal asphyxia, incubator admission and the need for resuscitation were significantly associated with the presence of congenital anomalies. Higher prevalence of congenital anomalies was observed in neonatesof grand multiparous women, diabetic mothers delivery by CS, cases with oligohydramnios and with positive consanguinity. Chromosomal abnormalities were found in 28 cases (27.18% of malformed cases) (5.6/1000). Numerical abnormalities were found in 22 cases (21.35%) (4.4/1000), Down syndrome in 16 cases, Edward syndrome in two cases, Patau syndrome in one case and Turner syndrome (monosomy) inthree cases. Structural abnormalities were present in six cases (5.83%) (1.2/1000), Down syndrome in two cases, Turner syndrome in two cases, balanced translocation [(12;13)(q15;q34)] with dysmorphic features and undescended testis in one case and deletion 9(q11;q31) with disorder of sex development in one case. To conclude karyotype should not be done routinely for all malformed cases as many of them are due to genetic syndromes. So, it is more useful to consult expert dysmorphologists for proper syndrome identification and for the decision to use more recent molecular techniques for diagnosis
Morphological and Biochemical Adaptive Changes Associated With A Short-period Starvation of Adult Male Japanese Quail (Coturnix japonica)
Objective: The morphological and biochemical impact of a short-period of starvation on Japanese quail was investigated.
Materials and Methods: Ten adult male Japanese quail were divided into two groups; control fed and starved. The control-fed group was offered food and water ad libitum and the starved group was subjected to a short-period of food deprivation. After 2.5 days, the serum was obtained and different parameters including the total protein, AST, ALT, triglyceride, HDL, LDL, creatinine and urea were assessed. Gastrointestinal tract, stomach and liver were excised and their masses were estimated. Paraffin and resin embedded sections from the proventriculus, gizzard, liver, duodenum, kidney and pancreas were examined with a light microscopy.
Results: Significant decreases in the masses of body, gastrointestinal tract, stomach and liver of the starved group were recorded. The liver and duodenum were the most affected organs. The liver showed depletion of glycogen, vacuolation, hyperemia and cellular infiltrations. Duodenal villi showed degenerative changes in lamina epithelialis and cellular infiltrations in the lamina propria. Biochemical analysis revealed a decreased level of total protein, AST and ALT, increased cholesterol, triglycerides and LDL and unchanged HDL, urea and creatinine by starvation.
Conclusion: The current study described in details the effect of short time starvation on quail organs. Time-point adaptive responses of male quail to starvation and refeeding will be investigated in future studies
Correlation of serum soluble endoglin to the severity of pre-eclampsia and its effect on the pregnancy outcome
Background: Preeclampsia is a major obstetric problem and a significant source of maternal and neonatal morbidity and mortality. Preeclampsia is associated with increased risks of placental abruption, acute renal failure, cerebrovascular and cardiovascular complications, disseminated intravascular coagulation, and maternal death. Consequently, early diagnosis of preeclampsia and close observation are imperative. In these cases of preeclampsia, combination of Doppler flowmetry and circulating angiogenic factors levels are recorded. Stepan et al examined endoglin, a cell-surface co-receptor for transforming growth factor in patients with Doppler flow patterns of preeclampsia at 19-24 weeks. Soluble endoglin levels were elevated in second trimester pregnancies with abnormal uterine perfusion in women who experienced preeclampsia. The aim of this study was to test if there is correlation between the level of serum endoglin in pregnant women with severe preeclampsia to the maternal and fetal outcome.Methods: This study was conducted on a group of 90 pregnant women attended to the Antenatal clinic and selected from the preeclampsia unit of EL- Shatby Maternity University Hospital, The selected patients were subdivided in two groups. Group A (control group): 30 cases of normotensive pregnant ladies. Group B (case group): 60 cases of severe preeclamptic pregnant ladies. Routine investigations, maternal serum soluble endoglin and ultrasound results were analysed and compared for both groups.Results: Significant correlation was found between severe preeclampsia and high level soluble endoglin. Significant correlation was found between high level of soluble endoglin and the occurrence of IUGR among the severe preeclamptic patients. Positive correlation was found between serum level of soluble endoglin and uterine artery PI and uterine artery RI, the higher the serum level of soluble endoglin the higher the uterine artery pulsatility and resistance index. Significant correlation was found between high level of soluble endoglin and the occurrence of specific complications, the higher the level of soluble endoglin the higher the risk of exposure to preeclampsia complications as the occurrence of eclamptic fits, the development of HELLP syndrome, the admission to the ICU, the admission of the baby to the NICU, and the fetal death.Conclusions: From our study, it is evident that serum endoglin rises during normal as well as preeclamptic pregnancy and that the rise in preeclampsia is much higher, the rise in endoglin levels may occur as early as the first trimester in pregnancies which later develop preeclampsia.  Hence, used alone or in combination with uterine artery Doppler flowmetry, the measurement of soluble serum endoglin has the potential for use as a predictive clinical test for preeclampsia risk assessment and could potentially improve the outcome of pregnancy
Bond strength and elemental analysis of oxidized dentin bonded to resin modified glass ionomer based restorative material
This study aimed to investigate the influence of hesperidin application on the bonding of resin-modified glass ionomer-based restorative material to dentin treated with oxygen-induced endodontic irrigants. One hundred human permanent molars were categorized into five groups (n= 20/group), treated with various irrigants as follows: Group C; distilled water (control group), Group SH; 5.25% NaOCl, Group SH+H; 5.25% NaOCl + 5 % hesperidin, Group HP; 10% H2O2, Group HP+H; 10% H2O2 + 5 % hesperidin. Specimens were bonded with RMGI based restorative material. For each group, half of the specimens were evaluated for µSBS by a universal testing machine and the other half for dentin ion uptake by EDX. Additional ten specimens (n=2/per group) were prepared for the micro-morphological analysis under SEM. Hesperidin groups improved the µSBS, with a significant effect for HP+H group (p<. 05). Dentin ion uptake was significantly (p<. 05) improved in hesperidin groups. In conclusion, Application of hesperidin in conjunction with RMGI based restorative material improved the dentin bond strength and ion uptake; this could be a promising approach to aid dental practitioners in their decisions, regarding which restorative material to use especially in caries susceptible patients
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