Six-year clinical performance of lithium disilicate glass-ceramic CAD-CAM versus metal-ceramic crowns

Ahmed Aziz,Omar El-Mowafy 대한치과보철학회 2023 The Journal of Advanced Prosthodontics Vol.15 No.1

PURPOSE. To assess the clinical performance of monolithic CAD-CAM lithium disilicate glass-ceramic (LDGC) crowns and metal-ceramic (MC) crowns provided by predoctoral students. This study also assessed the effects of patient and provider-related factors on their clinical performance as well as patient preference for these types of crowns. MATERIALS AND METHODS. Twenty-five patients who received 50 crowns (25 LDGC CAD-CAM and 25 MC) provided by predoctoral students were retrospectively examined. LDGC CAD-CAM crowns were milled in-house using the CEREC Bluecam system and cemented with either RelyX Unicem or Calibra Esthetic resin cements. MC crowns were cemented with RelyX Unicem cement. Clinical assessment of the crowns and the supporting periodontal structures were performed following the modified California Dental Association (CDA) criteria. Patients’ preference was recorded using a visual analog scale (VAS). The results were statistically analyzed using log-rank test, Pearson Chi-squared test and Kaplan-Meier survival analysis. RESULTS. Twelve complications were observed in the MC crown group (9-esthetic, 2-technical and 1-biological). In comparison, 2 complications in the LDGC CAD-CAM crown group were observed (1-technical and 1-esthetic). The 6-year cumulative survival rates for MC crowns and LDGC CAD-CAM were 90.8% and 96%, respectively, whereas the success rates were 83.4% and 96%, respectively. Overall, patients preferred the esthetic outcomes of LDGC CAD-CAM crowns over MC crowns. CONCLUSION. The high survival and success rates, low number of complications, and the high level of patients’ acceptance of monolithic LDGC CAD-CAM crowns lend them well as predictable and viable alternatives to the “gold standard” MC crowns.

Effect of heating cycle on cobalt-antimonide-based thin films for high-temperature thermoelectric energy conversion applications

Ahmed, Aziz,Han, Seungwoo Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.790 No.-

<P><B>Abstract</B></P> <P>In this study, a comparative analysis of the structural and thermoelectric properties of all possible Co-Sb-based phases in thin-film form for high-temperature applications is presented and discussed. A series of thin-film samples were prepared via radiofrequency co-sputtering on an oxidized silicon substrate. For improved crystallinity, the thin-film samples were subjected to heat treatment in the form of a high-temperature heating cycle where the temperature was slowly ramped up to about 760 K. The films were characterized using X-ray diffraction for phase identification and crystalline quality. Energy-dispersive spectroscopy was performed to determine the stoichiometric composition and homogeneity, whereas the surface morphology and microstructure were examined using scanning electron microscopy and atomic force microscopy. To investigate film performance at high temperatures, the electrical resistivity and Seebeck coefficient were measured at regular temperature intervals, and results were correlated with identified phases, composition, and crystalline quality. The CoSb phase was observed to have metallic features, the CoSb<SUB>2</SUB> phase had doped semiconductor characteristics, whereas the CoSb<SUB>3</SUB>-phase thin films showed typical semiconductor behavior. The CoSb<SUB>2</SUB> and CoSb<SUB>3</SUB> samples shows a transition of the Seebeck coefficient from positive to negative at a temperature range of 500–550 K and 550–600 K respectively. The thermoelectric power factor was evaluated from the measured parameters and maximum values of 3.2, 7.8, and 3.8 mWm<SUP>−1</SUP>·K<SUP>−2</SUP> for the CoSb, CoSb<SUB>2</SUB>, and CoSb<SUB>3</SUB> thin films, respectively, are reported. We observed a wide range of structural and thermoelectric properties in the series of samples, demonstrating a route to tailoring and improving properties for maximal performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermopower depends upon both the carrier concentration and electron effective mass. </LI> <LI> The presence of impurity phases shapes the magnitude of the Seebeck coefficient. </LI> <LI> Seebeck coefficient retained the p to n type transition in the second heating cycle. </LI> <LI> A Seebeck coefficient as high as −227 μV/K was achievable for CoSb<SUB>3</SUB> thin films. </LI> <LI> CoSb<SUB>3</SUB> skutterudite thin films achieved a sound maximum power factor of 4 mW/m.K<SUP>2</SUP>. </LI> </UL> </P>

Effect of Sb content on the thermoelectric properties of annealed CoSb₃ thin films deposited via RF co-sputtering

Ahmed, Aziz,Han, Seungwoo Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.408 No.-

<P><B>Abstract</B></P> <P>A series of CoSb<SUB>3</SUB> thin films with Sb contents in the range 70–79at.% were deposited at room temperature via RF co-sputtering. The thin films were amorphous in the as-deposited state and annealed at 300°C for 3h to obtain crystalline samples. The annealed thin films were characterized using scanning electron microscopy and X-ray diffraction (XRD), and these data indicate that the films exhibited good crystallinity. The XRD patterns indicate single-phase CoSb<SUB>3</SUB> thin films in the Sb-rich samples. For the Sb-deficient samples, however, mixed-phase thin films consisting of CoSb<SUB>2</SUB> and CoSb<SUB>3</SUB> components were obtained. The electrical and thermoelectric properties were measured at temperatures up to 760K and found to be highly sensitive to the phases that were present. We observed a change in the thermoelectric properties of the films from <I>p</I>-type at low temperatures to <I>n</I>-type at high temperatures, which indicates potential applications as <I>n</I>-type thermoelectric thin films. A large Seebeck coefficient and power factor was obtained for the single-phase CoSb<SUB>3</SUB> thin films. The CoSb<SUB>2</SUB> phase thin films were also found to possess a significant Seebeck coefficient, which coupled with the much smaller electrical resistivity, provided a larger power factor than the single-phase CoSb<SUB>3</SUB> thin films. We report maximum power factor of 7.92mW/mK<SUP>2</SUP> for the CoSb<SUB>2</SUB>-containing mixed phase thin film and 1.26mW/mK<SUP>2</SUP> for the stoichiometric CoSb<SUB>3</SUB> thin film.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CoSb<SUB>3</SUB> phase thin films were prepared using RF co sputtering method. </LI> <LI> Thin film thermoelectric properties were hugely dependent on Sb content. </LI> <LI> All thin films shows <I>n</I>-type conduction behavior at high temperatures. </LI> <LI> The thin films with excess Sb possess the largest Seebeck coefficient. </LI> <LI> The thin films with CoSb<SUB>2</SUB> phase possess the largest power factor. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>The X-ray diffraction patterns and temperature dependence of the Seebeck coefficient of the annealed Co–Sb thin films.</P> <P>[DISPLAY OMISSION]</P>

Preparation and Thermoelectric Properties of RF Co-sputtered CoSb3 Skutteruddite Thin Films

Aziz Ahmed,한승우 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.10

Various skutterudites have been under investigation because of their potential application inthermoelectric materials and devices. These studies indicate that bulk materials with a skutteruditetypestructure show reasonable thermoelectric behaviors at elevated temperatures, which make themsuitable for high-temperature thermoelectric applications. The results of thermoelectric-propertymeasurements on skutterudite-phase CoSb3 thin films are presented in this study in order to extendthe bulk material concept to micro-device applications by using thin film deposition technology. Thin films are deposited on oxidized silicon substrates by using the RF co-sputtering method. Thefilm’s composition is found to depend strongly on the deposition conditions. The temperature atwhich the deposited films transition from an amorphous state to a crystalline state has been reportedto be about 153 C. Therefore, some experiments are performed with the substrate temperaturekept at 200 C to obtain polycrystalline films. The crystal structure of the film is evaluated byusing x-ray diffraction (XRD) measurements. Energy dispersive spectroscopy (EDS) is used todetermine the film’s composition whereas the surface morphology and the thickness are investigatedand measured by using scanning electron microscopy (SEM). Finally, the thermoelectric properties,namely, the electrical resistivity and the Seebeck coefficient, are used to calculate the power factorof the deposited thin films and, their variations with temperature are measured. We report amaximum power factor of 0.41 mW/mK2 for the film deposited at a 200 C substrate temperature.

Pectoral nerve blocks for transvenous subpectoral pacemaker insertion in children: a randomized controlled study

Elhaddad Ahmed Mohamed,Hefnawy Salwa Mohamed,El-Aziz Mohamed Abd,Ebraheem Mahmoud Mostafa,Mohamed Ahmed Kareem 대한마취통증의학회 2023 Korean Journal of Anesthesiology Vol.76 No.5

Background: Postoperative pain management after pacemaker insertion routinely requires opioid agents, nonsteroidal anti-inflammatory drugs, or paracetamol. However, interest in opioid-sparing multimodal pain management to minimize postoperative narcotic use has increased recently. This study aimed to assess the pectoral nerve (PECS) block versus standard treatment on postoperative pain control and opioid consumption in pediatric patients after transvenous subpectoral pacemaker insertion.Method: In this randomized controlled study, 40 pediatric patients underwent transvenous subpectoral pacemaker insertion with either congenital or postoperative complete heart block. Patients were randomly assigned to two groups: Group C (control) received conventional analgesic care without any block and Group P (pectoral) received a PECS block. Demographics, procedural variables, postoperative pain, and postoperative opioid consumption were compared between the two groups.Results: In children undergoing transvenous subpectoral pacemaker insertion, the PECS block was associated with a longer procedure time; however, the cumulative dose of fentanyl and atracurium was reduced and the hemodynamic profile was superior in Group P compared with Group C intraoperatively. Postoperatively, the PECS block was associated with lower postprocedural pain scores, which was reflected by the longer interval before the first call for rescue analgesia and lower postoperative morphine consumption, without an increase in the rate of complications.Conclusion: Ultrasound-guided PECS blocks are associated with a good intraoperative hemodynamic profile, reduced postoperative pain scores, and lower total opioid consumption in children undergoing transvenous subpectoral pacemaker placement.

Prognostic performance of combined use of high-sensitivity troponin T and creatine kinase MB isoenzyme in high cardiovascular risk patients with end-stage renal disease

Khaled Abdul-Aziz Ahmed,Wahda Mohammed Al-Attab 대한신장학회 2017 Kidney Research and Clinical Practice Vol.36 No.4

Background: The principal goal of this study was to determine the importance of high-sensitivity troponin T (hs-TnT) and creatine kinase MB isoenzyme (CK-MB) in predicting cardiovascular events in asymptomatic end-stage renal disease (ESRD) patients.Methods: This study included 110 participants; 54 ESRD patients undergoing hemodialysis and 56 healthy control participants. Biochemical parameters and cardiac markers were estimated. Comparative utilities were assessed through logistic regression and receiver operating characteristic (ROC) analyses.Results: We found that 96.3% of ESRD patients had an elevated level of hs-TnT (mean, 0.049 ± 0.0324 μg/L) compared to healthy participants. Among patients with ESRD, hs-TnT showed significant correlations with the low-density lipoprotein cholesterol/high-density lipoprotein cholesterol (HDL-C) (P = 0.042, r = 0.278) and total cholesterol/HDL-C (P = 0.044, r = 0.276) ratios. CK-MB (odds ratio [OR], 1.138; P = 0.04) and hs-TnT (OR, 2.153; P = 0.017) predicted cardiovascular events on logistic regression analysis, and the prediction was improved by the model that combined two cardiac markers. The diagnostic performance of hs-TnT and CK-MB alone and the combination of the two biomarkers was assessed by the area under the ROC curve (AUC). The highest AUC was produced by the combination of hs-TnT and CK-MB markers (0.920) compared to hs-TnT or CK-MB alone.Conclusion: In asymptomatic patients with ESRD, hs-TnT appeared to be an important predictor for cardiovascular mortality, and its diagnostic accuracy improved with CK-MB. This study provides new insights into the predictive value of multiple biomarkers for identifying cardiovascular events in ESRD patients on hemodialysis.

Electrochemical Adsorption Properties and Inhibition of Zinc Corrosion by Two Chromones in Sulfuric Acid Solutions

Fouda, Abd El-Aziz S.,Nazeer, Ahmed Abdel,Saber, Ahmed Korean Chemical Society 2014 대한화학회지 Vol.58 No.2

The electrochemical behavior and corrosion inhibition of zinc in 0.5 M $H_2SO_4$ in the absence and presence of some chromones has been investigated using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The presence of these investigated compounds in the corrosive solutions decrease the weight loss, the corrosion current density, and double layer capacitance but increases the charge transfer resistance. Polarization studies were carried out at room temperature, and showed that all the studied compounds act as mixed type inhibitors with a slight predominance of cathodic character. The effect of temperature on corrosion inhibition has been studied and the thermodynamic activation and adsorption parameters were determined and discussed. The adsorption of the investigated compounds on zinc was found to obey Langmuir adsorption isotherm.

Immunohistochemical Expression of Cytokeratins and Epithelial Membrane Protein 2 in Nasopharyngeal Carcinoma and its Potential Implications

Ahmed, Hussain Gadelkarim,Suliman, Rania Saad Abdul Gader,Abd El Aziz, Mohammed Siddig,Alshammari, Fawaz D. Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.2

Background: Nasopharyngeal carcinoma (NPC) is an aggressive disease and tends to involve surrounding tissues, and biomarkers for better management are yet to be identified. Materials and Methods: One hundred and fifty tissue samples with NPC diagnosis were were investigated using pan cytokeratin (CK) and epithelial membrane protein 2 (EMP2) antibodies. Results: Immunohistochemical expression of CK was identified in 144/150 (96%) and of EMP2 in 120/150 (80%). Conclusions: There is a high loss of EMP2 in NPC, especially high grade examples. Loss of CK expression is also linked to high grade NPC types.

Socioeconomic Impacts of Gluten-Free Diet among Saudi Children with Celiac Disease

Ahmed Sarkhy,Mohammad I. El Mouzan,Elshazaly Saeed,Aziz Alanazi,Sharifa Alghamdi,Shirin Anil,Asaad Assiri 대한소아소화기영양학회 2016 Pediatric gastroenterology, hepatology & nutrition Vol.19 No.3

Purpose: To determine the socio-economic impact of gluten free diet (GFD) on Saudi children and their families Methods: A cross-sectional study was conducted in which an online questionnaire was sent to all families registered in the Saudi celiac patients support group. We included only children (age 18 years of age and younger) with biop-sy-confirmed celiac disease (CD).Results: A total of 113 children were included in the final analysis, the median age was 9.9 years; 62.8% were females. One hundred (88.5%) of the participating families reported that GFD food was not easily available in their areas, 17% of them reported that it was not available at all in their area. One hundred and six (93.8%) reported that the price of GFD food was very expensive and 70 (61.9%) families that the diet was heavily affecting their family budget. Significant social difficulties were reported among the participating families and their children including interference with the child’s interaction with other children (49.6%), the families’ ability to attend social gatherings (60.2%), the families’ ability to eat in restaurants (73.5%), and the families’ ability to travel (58.4%). Conclusion: There is significant negative socio-economic impact of GFD on children with CD & their families. Health care providers should be aware of these psycho-social difficulties and be well trained to provide a proper education and psychological support for these patients and their families.

Clinical Characteristics of Celiac Disease and Dietary Adherence to Gluten-Free Diet among Saudi Children

Ahmed Al Sarkhy,Mohammad I. El Mouzan,Elshazaly Saeed,Aziz Alanazi,Sharifa Alghamdi,Shirin Anil and Asaad Assiri 대한소아소화기영양학회 2015 Pediatric gastroenterology, hepatology & nutrition Vol.18 No.1

Purpose: To describe the clinical characteristics of celiac disease (CD) among Saudi children and to determine the adherence rate to gluten free diet (GFD) and its determinant factors among them.Methods: A cross-sectional study was conducted, in which all the families registered in the Saudi Celiac Patients Support Group were sent an online survey. Only families with children 18 years of age and younger with biopsy-con-firmed CD were included.Results: The median age of the 113 included children was 9.9 years, the median age at symptom onset was 5.5 years and the median age at diagnosis was 7 years, the median time between the presentation and the final diagnosis was 1 year. Sixty two of the involved children were females. Ninety two percent of the patients were symptomatic at the diagnosis while eight percent were asymptomatic. The commonest presenting symptoms included: chronic abdominal pain (59.3%), poor weight gain (54%), abdominal distention, gases, bloating (46.1%) and chronic diarrhea (41.6%). Sixty percent of the involved children were reported to be strictly adherent to GFD. Younger age at diagnosis and shorter duration since the diagnosis were associated with a better adherence rate. Conclusion: CD has similar clinical presentations among Saudi children compared to other parts of the ward; however, the adherence to GFD is relatively poor. Younger age at diagnosis and shorter duration since the diagnosis were associated with a better adherence rate.