Assessment of relative translucency and resultant color of contemporary resin-matrix ceramics indicated for laminate veneers and full crowns.

Background and Aims: Evaluation of the optical properties of restorative materials is an important parameter for identifying clinical success. The aim of this study was to compare the translucency of contemporary resin-matrix ceramics (RMCs) and to evaluate the effect of cement shade on the final color of RMCs indicated for laminate veneers and full crowns. Materials and Methods: A hundred A2 shade RMC specimens were fabricated by using Mazic Duro (MD), CAMouflage NOW (CN), KZR-CAD HR2 (KZR), Grandio Block (GB), and Brilliant Crios (BC) at 0.7-mm and 1.5-mm thicknesses (n = 10). A2 shade composite resin was used for the foundation structure. Twenty resin-cement specimens were prepared from A2 and translucent shades at 0.1-mm thickness. Interchangeably, the foundation-cement-resin matrix ceramic assemblies were created with optical gel. The color coordinates were recorded using a spectrophotometer. After calculating translucency parameter (TP00) and color difference (ΔE00) values, data were analyzed statistically (P = 0.05). Results: TP00 values were influenced by RMC type and thickness. TP00 values of RMCs can be listed in descending order as MD>GB = CN>BC=KZR. ΔE00 values were significantly influenced by all parameters and their interactions. MD exhibited higher ΔE00 values among tested RMCs. The effect of A2 cement was not perceived visually while TR cement demonstrated visually perceptible but clinically acceptable values for both laminate veneers and full crowns. As the material thickness decreased, the TP00 and ΔE00 values increased in all RMCs. Conclusions: Clinicians should carefully prefer cement shade and RMC material by contemplating their impact on the optical properties particularly when the restoration is thin.

Study of structural, elastic, electronic, and vibrational properties of MRh2O4 (M = Cd and Zn) spinels: DFT-based calculations.

Solar-assisted water splitting using photoelectrochemical cells (PECs) is one of the promising ways for the production of hydrogen to store renewable energy. Semiconducting materials are used as a key factor which controls the overall energy conversion efficiency in PECs. However, finding new semiconductors with appropriate properties (stability, efficient charge separation and transport, abundant and visible light absorption) is still a challenge for developing new materials for solar water splitting. Spinel-type structures which have suitable band gaps for visible light harvesting are promising candidates for PEC applications. In this study, first principles method within density functional theory (DFT) have been used to study the structural, elastic, electronic, and vibrational properties of MRh2O4 (M = Cd and Zn) for cubic spinel phase. Present study reveals that the CdRh2O4 and ZnRh2O4 in spinel structure are semiconducting in nature and they also satisfy the stability criterion. Thus, studied spinels can be used as semiconductors in PEC applications.

First principles investigations of the structural, elastic, vibrational, and thermodynamic properties of TiMg2O4 oxide spinels: cubic and tetragonal phases.

In the present study ab initio methology under density functional theory with generalized gradient approximation is used to study the structural, elastic, and vibrational properties of TiMg2O4 with cubic and tetragonal phases with space groups (Fd[Formula: see text]m) and P4_122, respectively. The present study shows that the studied compound TiMg2O4 is mechanically stable in both phases. Both phases have ductile nature and strong anisotropic properties, and it is also observed that the tetragonal phase has more anisotropic properties compared to the cubic phase. Obtained structural parameters are in good agreement with related literature.

Nanoparticle embedded enzymes for improved lateral flow sensors.

In this study, combining the nanoparticle embedded sensors with lateral flow assays, a novel strategy for ensuring the quality of signalling in lateral flow assays (LFAs) was developed. A LFA for reactive oxygen species (ROS) is reported that is based on horse radish peroxidase (HRP) which is co-entrapped with Texas Red dextran inside porous polyacrylamide nanoparticles. In this system, enzymes are protected in the porous matrix of polyacrylamide which freely allows the diffusion of the analyte. The sensor is rapid and sensitive for quantification of hydrogen peroxide concentrations. A test solution of hydrogen peroxides was quantified with this novel LFA-ROS sensor to obtain a linear range between 1 and 25 µM. Nanoparticle embedding of enzymes is proposed here as a general strategy for developing enzyme-based lateral flow assays, eliminating adverse effects associated with biological samples.

Ceramic encapsulated latex composites.

This work reports the encapsulation of latex particles in Al2O3-polystyrene (PS) composite films. These films were prepared from PS particles in Al2O3 dispersion at room temperature in various latex contents. Composite films were annealed at elevated temperatures in 10 min time interval above the glass transition temperature (Tg) of polystyrene. Transmitted photon intensities, I(tr) were monitored after each annealing step. AFM micrographs were also used to observe the physical changes of the composite films during annealing. It was observed that latex particles are encapsulated above a critical Al2O3 content of 33 wt% which corresponds to the critical occupation probability of p(c) = 0.33 at which the film obey the site-percolation model with a critical exponent of 0.45. Below p(c), it was seen that complete latex film formation process took place, where transparency of the film was increased by annealing.

Fast transient fluorescence technique (FTRF) for studying vapor-induced latex film formation.

A fast transient fluorescence (FTRF) technique was used to study latex film formation induced by organic solvent vapor. Seven different films with the same latex content were prepared separately from poly(methyl methacrylate) (PMMA) particles and exposed to vapor of various chloroform-heptane mixtures in seven different experiments. Latex films were prepared from pyrene (Py)-labeled latex particles and fluorescence lifetimes of Py were monitored during vapor-induced film formation. It was observed that pyrene lifetimes decreased as vapor exposure time increased. A Stern-Volmer kinetic analysis was used for low quenching efficiencies to interpret the decrease in pyrene lifetimes. A Prager-Tirrel model was employed to obtain back-and-forth frequencies, nu, of the reptating PMMA chains during latex film formation induced by solvent vapor. nu values were found to be correlated with chloroform content in vapor mixture. It was observed that polymer interdiffusion obeyed a t(1/2) law during film formation. The results of optical transmission experiments were found to support these findings.

Effect of gamma Irradiation on Latex Film Dissolution.

Latex films have been prepared by annealing pyrene (Py)-labeled poly(methyl methacrylate)-polyisobutylene particles at the glass transition temperature (100 degrees C). These films were then irradiated by gamma rays from (60)Co in a gamma cell at room temperature at various dose rates (rad/h). Before dissolution the films were annealed at 200 degrees C for a 30 min time interval to complete the film formation process. Steady-state fluorescence techniques were used to monitor the dissolution of irradiated latex films. Dissolution of films in a chloroform-heptane (80%-20%) mixture was monitored in real time by the Py fluorescence intensity change. Relaxation constants, k(0), and dissolution coefficients, D(d), of polymer chains were measured. Two different regimes of D(d) values were observed during dissolution, which are related to two different molecular weight distributions caused by scission and branching of polymer chains when they were irradiated and annealed. Copyright 2001 Academic Press.

Analysis of patients admitted to the emergency unit of a university children's hospital in Turkey.

A retrospective analysis of the computerized data of patients admitted to our Emergency Unit Inpatient Service in 1991 was conducted to obtain data about age, sex, referred sources, admission period, monthly admission rates, diagnoses and eventual outcome. More than 47% of patients were younger than one year of age. The most common causes for hospital admission were infectious, respiratory and neurological diseases. The mean hospitalization period was 3.26 days. More than 60% of patients were treated by the Emergency Unit staff. The net mortality rate was 2.9%, infectious diseases being the most common cause of mortality. We conclude that demographic and diagnostic data regarding admissions to the Emergency Unit can be utilized to develop new strategies for patient care and to reorganize education programs for pediatric residents.

The impact of systematic use of oral rehydration therapy on outcome in acute diarrheal disease in children.

A review of our experience with diarrheal disease (DD) at the University of Istanbul Children's Hospital in Capa, covering the years 1987 to 1989, is presented in this paper. DD is one of the most common conditions encountered among patients presenting to the outpatient clinic (5.9% of all cases). The majority of DD cases were in the four- to 12-month age group. During the surveillance period, summertime peaks in DD were observed, suggesting an increase in bacterial infection. Out of 8749 cases of DD, 5.2% showed severe dehydration. Rates of hospitalization for DD did not show any differences over the three years. However, mortality from DD significantly decreased from 1.15 to 0.57% during this three-year period. This was attributed to more rational use of oral rehydration solutions, as a result of the close monitoring and recording of findings introduced by the protocol of this study. Malnutrition, sepsis, pneumonia, and other severe systemic diseases were found to be the most important risk factors affecting hospitalization and mortality rates. Infants, especially those under three months, had the highest risk for hospitalization and mortality.

Case of spontaneous haemothorax associated with an endodermal sinus tumour.

Spontaneous haemothorax is rare in infants. A case is reported of a nine month old infant who was found to have an endodermal sinus tumour.

Intraspinal hemorrhage in a child with factor XIII deficiency.

The rarity of spinal cord injuries and hemorrhages and of fibrin-stabilizing factor XIII deficiency during childhood has induced us to report the case of this two-year-old boy with factor XIII deficiency who presented with cervical intraspinal hemorrhage between the C4 and C7 levels as well as paraplegia presumably following a minor trauma. The findings in this patient, who was brought in two weeks after the appearance of the first symptoms, indicate the importance of early diagnosis and early intervention to minimize the extent of the damage from the injury in such cases. The case also points to the need for close follow-up of patients with factor XIII deficiency for CNS bleeding.

Intrahepatic hematoma: a rare complication of exchange transfusion.

A four-day-old male neonate who underwent three exchange transfusions for jaundice owing to ABO incompatibility on three consecutive days is presented. A large intrahepatic hematoma developed as a complication of the third exchange transfusion. The baby fully recovered.

Experience with diarrheal disease in a university pediatric hospital.

In 1987, 3227 diarrhea cases, half of which were infants, presented at the Out-patient Department of the Istanbul University Children's Hospital. An examination of these cases showed that in 1,066 cases diarrheal disease (DD) was accompanied by a coexisting infection or other disease. The cases with severe dehydration, shock or severe systemic disease were immediately hospitalized. All the remaining cases were administered oral rehydration therapy (ORT) in the Diarrhea Unit, and 94.7 percent of them were successfully rehydrated with ORT. Severe dehydration, shock, severe systemic infection, abdominal distention, failure of rehydration by the enteral route, severe protein energy malnutrition (PEM), and the presence of convulsions were the indications for i.v. therapy. The overall mortality rate was 11 percent. Our experience with DD indicates that widespread implementation of ORT in diarrheal disease and the establishment of Diarrhea Units in large hospitals will contribute not only to saving more lives but will also have an economic impact by reducing the number of admissions.

Serum insulin and blood glucose levels in breast-fed and formula-fed infants in the first week of life.

Serum insulin and blood glucose levels were measured in newborns aged four to eight hours and those aged seven days who were either breast fed or formula fed. With both types of feeding, the maximum serum insulin levels occurred 60 minutes postprandially in four- to eight-hour-old infants and 30 minutes postprandially in seven-day-old babies. Between breast-fed and formula-fed groups, no statistically significant difference was found in postprandial serum insulin levels or (except for the 90-minute values on the seventh day) in blood glucose levels. It may be necessary to examine the metabolic-endocrine responses to formula administered as the only feeding over a long period to determine whether formula feeding alters such physiologic mechanisms as pancreatic function and immunity in early life and thereby affects the development of the child.