417 research outputs found
Axially and Peripherally Substituted Phthalocyanine and Azaphthalocyanine Complexes for Heterojunction Design
The aim of this work was to synthesize novel phthalocyanines and pyrazinoporphyrazines with the main group elements and transition metals. The conformational rigidity and the steric bulk of their peripherally annelated cyclohexene rings tend to reduce the degree of aggregation, thus enhancing the solubility of these 42 π- Hückel aromatic system without inhibiting their tendencies to form crystalline phases. For central metals having an oxidation state > II, the possibility of introducing anionic axial ligands Lax, at the metal center was investigated and the optical properties of these chromophores were determined. In addition to their high solubility, some of the synthesized chromophores were found to be sublimable. Phthalocyanines and related compounds are interesting materials for optoelectronic applications; thus, a study of the electronic HOMO and LUMO alignment and coupling of these new chromophores at different heterojunction interfaces is outlined
p-Convex Functions in Discrete Sets
We study the new concept of a p-convex function and A-p-convex sets for somenbsp set A of a vector spacenbsp E. These concepts may have applications in convex and non linear analysis and other topics of mathematical sciences
Development of numerical wave power prediction tool offshore oscillating water column wave energy converter
Marine renewable energy sources are crucial alternatives for a sustainable development. The idea of generating electrical power from water waves has been realized for many years. In fact, waves are now considered as an ideal renewable energy source since a Wave Energy Converter (WEC) has no fuel cost and provides cleanly a high power density that is available most of the time. The third generation of WECs is intended to be installed offshore. This allows the device to harvest the great energy content of waves found in deep water and minimise the environmental impacts of the device. On the other hand, moving WECs to offshore locations will increase the initial and maintenance costs. So many types of device may be suggested for wave power extraction that the task of selecting a particular one is made complicated. Therefore modelling of different WECs allows the comparison between them and the selection of the optimum choice. Recent studies showed that the SparBuoy Oscillating Water Column (OWC) has the advantage of being simple, axi-symmetrical, and equally efficient at capturing energy from all directions, but its efficiency (capture factor) is affected significantly by the incident wave periods variation due to the dynamic coupling of the water column and the floating structure. The proper modelling of the device allows the optimization of the geometries and the Power Take-Off (PTO) mechanism in order to maximise the power absorbed. The main objective of this research is to develop experimentally validated numerical wave power prediction tool for offshore SparBuoy OWC WEC. The numerical tool should be able to predict the spar motions and the water column oscillations inside the structure, in addition to the estimation of the pneumatic power absorber and the evaluation of the device performance. Three uncoupled linear second order differential equations have been used to predict the spar surge, heave and pitch motions, where wave forces have been calculated analytically in frequency domain in inertia and diffraction regimes. Mooring system has been involved in surge motion only using static and quasi-static modelling approaches.;Finite element multi-static model have been developed using OrcaFlex to validate the analytical results. Single Degree of Freedom (DOF) mechanical oscillation model has been presented to simulate the water column oscillations inside captive cylindrical OWC where PTO damping and stiffness due to air compressibility inside the pneumatic chamber have been taken into account linearly. Later on, nonlinearity due to large waves has been investigated. Linearized frequency domain model based on classical perturbation theory and nonlinear model where wave forces are calculated in time domain have been proposed. Furthermore, nonlinearity due to damping forces has been considered. First, iterative procedure has been used to optimise the linear and quadratic damping coefficients in frequency domain. Then, another model has been provided where equivalent viscous damping coefficients are calculated in time domain by taking into consideration the instant oscillation amplitude. Finally the nonlinear effects due to air compressibility inside the OWC chamber has been considered in a time domain model which include the water column oscillations amplitudes. Two different dynamic models have been implemented to describe floating OWC and will be referred to in the text as simplified 2DOF model and Szumko model. Both models considered two translational modes of motions in heave direction. Simplified 2DOF model has been solved analytically in frequency domain due to its simplicity, while numerical solutions in time domain have been provided for both models using Matlab. Different approaches have been adopted to modify both models in order to obtain a satisfactory agreement between the predicted and measured results. A floating platform consists of four similar SparBuoy OWC WECs rigidly attached together by trusses where spars are located at the corners have been tested experimentally. Numerical model has been developed to predict the platform motions. Finally the experimental results have been compared to those obtained from the modelling of single SparBuoy OWC.Marine renewable energy sources are crucial alternatives for a sustainable development. The idea of generating electrical power from water waves has been realized for many years. In fact, waves are now considered as an ideal renewable energy source since a Wave Energy Converter (WEC) has no fuel cost and provides cleanly a high power density that is available most of the time. The third generation of WECs is intended to be installed offshore. This allows the device to harvest the great energy content of waves found in deep water and minimise the environmental impacts of the device. On the other hand, moving WECs to offshore locations will increase the initial and maintenance costs. So many types of device may be suggested for wave power extraction that the task of selecting a particular one is made complicated. Therefore modelling of different WECs allows the comparison between them and the selection of the optimum choice. Recent studies showed that the SparBuoy Oscillating Water Column (OWC) has the advantage of being simple, axi-symmetrical, and equally efficient at capturing energy from all directions, but its efficiency (capture factor) is affected significantly by the incident wave periods variation due to the dynamic coupling of the water column and the floating structure. The proper modelling of the device allows the optimization of the geometries and the Power Take-Off (PTO) mechanism in order to maximise the power absorbed. The main objective of this research is to develop experimentally validated numerical wave power prediction tool for offshore SparBuoy OWC WEC. The numerical tool should be able to predict the spar motions and the water column oscillations inside the structure, in addition to the estimation of the pneumatic power absorber and the evaluation of the device performance. Three uncoupled linear second order differential equations have been used to predict the spar surge, heave and pitch motions, where wave forces have been calculated analytically in frequency domain in inertia and diffraction regimes. Mooring system has been involved in surge motion only using static and quasi-static modelling approaches.;Finite element multi-static model have been developed using OrcaFlex to validate the analytical results. Single Degree of Freedom (DOF) mechanical oscillation model has been presented to simulate the water column oscillations inside captive cylindrical OWC where PTO damping and stiffness due to air compressibility inside the pneumatic chamber have been taken into account linearly. Later on, nonlinearity due to large waves has been investigated. Linearized frequency domain model based on classical perturbation theory and nonlinear model where wave forces are calculated in time domain have been proposed. Furthermore, nonlinearity due to damping forces has been considered. First, iterative procedure has been used to optimise the linear and quadratic damping coefficients in frequency domain. Then, another model has been provided where equivalent viscous damping coefficients are calculated in time domain by taking into consideration the instant oscillation amplitude. Finally the nonlinear effects due to air compressibility inside the OWC chamber has been considered in a time domain model which include the water column oscillations amplitudes. Two different dynamic models have been implemented to describe floating OWC and will be referred to in the text as simplified 2DOF model and Szumko model. Both models considered two translational modes of motions in heave direction. Simplified 2DOF model has been solved analytically in frequency domain due to its simplicity, while numerical solutions in time domain have been provided for both models using Matlab. Different approaches have been adopted to modify both models in order to obtain a satisfactory agreement between the predicted and measured results. A floating platform consists of four similar SparBuoy OWC WECs rigidly attached together by trusses where spars are located at the corners have been tested experimentally. Numerical model has been developed to predict the platform motions. Finally the experimental results have been compared to those obtained from the modelling of single SparBuoy OWC
Impact of New Large Aircraft on Airport Flexible Pavements
The objective of the study is to evaluate the effects of New Large Aircraft (NLA) on airport flexible pavement in terms of its expected impact on pavement life. The study is conducted using Hurghada Airport air fleet composition at four hypothetical annual departure levels, four standard subgrade strength categories, and introducing NLA at five different percentages. On the basis of the results of this research, it is concluded that, where an airport has a subgrade with CBR values higher than 6%, airport authority may permit the operation of A380 up to an additional 3% of the existing annual departures without losing more than 10 to 30 percent of pavement life. For airports with CBR values less than 6%, a significant reduction in pavement life as high as 40 to 90% should be anticipated in case of introducing the A380 at 3 percent share in the traffic mix or more. In case of subgrade strength CBR less than 6%, there is a high rate of pavement life reduction due to introduction of A380 up to 2% share in the traffic mix. However, there is a low rate of pavement life reduction due to introduction of A380 from 2% and up to 5% share in the traffic mix. Keywords: Airports, New Large Aircraft, NLA, Flexible pavements, A38
(R, S) conjugate solution to coupled Sylvester complex matrix equations with conjugate of two unknowns
In this work, we are concerned with (R, S) – conjugate solutions to coupled Sylvester complex matrix equations with conjugate of two unknowns. When the considered two matrix equations are consistent, it is demonstrated that the solutions can be obtained by utilizing this iterative algorithm for any initial arbitrary (R,S) – conjugate matrices V1,W1. A necessary and sufficient condition is established to guarantee that the proposed method converges to the (R,S) – conjugate solutions. Finally, two numerical examples are provided to demonstrate the efficiency of the described iterative technique
Physical therapy in burn wound healing: Development of clinical prediction rules to identify the efficacy of pulsed electromagnetic therapy
Many studies have demonstrated the effect of pulsed electromagnetic therapy (PEMT) on wound healing. This study aimed to develop a clinical prediction rule (CPR) to assess PEMT's efficacy in burn healing, potentially enhancing treatment decisions and outcomes. It was a one-group intervention study with 46 patients (21 males, 25 females) aged 20 to 55 years, having partial-thickness burns in the first or second healing stage, and a total burned surface area (TBSA) over 15%. The intervention involved pulsed electromagnetic therapy (Fisioline, Italy) for up to six weeks, with 60-minute sessions at 12 Hz and 12 Gauss, three times per week. The statistical analysis was conducted using the SPSS. The study revealed a significant decline in wound surface area (WSA) post-intervention (p < 0.05). A significant negative relationship was found between wound improvement and both age and total body surface area (TBSA) (p < 0.05), while a significant positive relationship was observed between wound improvement and initial wound size (p < 0.05). No significant relationship was found between wound improvement and wound stage (p > 0.05). The study concluded that pulsed electromagnetic therapy significantly reduces wound surface area. Additionally, age, TBSA, and initial burn wound size are important predictors of the therapy's efficacy in treating burn wounds.
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Validation of the PILL-5: A 5-Item Patient Reported Outcome Measure for Pill Dysphagia.
Objectives: Pill dysphagia is common and costly with a significant risk of pill retention, caustic injury, and poor medication compliance. The purpose of this investigation was to determine the validity and reliability of the PILL-5, a self-administered patient reported outcome measure (PROM) to quantify the degree of pill (tablet and capsule) dysphagia. The PILL-5 is a 5-item questionnaire with a maximum symptom score of 20. Methods: The PILL-5 was administered to 190 patients with dysphagia referred for videofluoroscopic esophagography (VFE). Construct validity was assessed by comparing PILL-5 composite scores to delayed barium tablet transit on VFE. Normative data was obtained by administering the instrument to a cohort of healthy community based volunteers. Internal consistency was assessed with the Cronbach alpha. Test/retest reliability was determined by administering the instrument to the same cohort of patients at two time points. Results: The mean PILL-5 was 5.6 (±4.9) for persons with dysphagia and 1.6 (±2.7) for healthy volunteers (p < 0.001). The internal consistency of the instrument was high (Cronbach alpha = 0.85). The mean PILL-5 was 4.3 (±4.1) for patients with normal transit and 7.6 (±5.3) for patients with delayed barium tablet transit on esophagography, indicating excellent criterion based validity (p < 0.001). Reproducibility was high with an intraclass correlation coefficient of 0.83 (p < 0.001). Conclusions: Healthy individuals report some degree of swallowing difficulty with pills. Normative data suggest that a PILL-5 > 6 is abnormal (mean + 2 SD). The instrument demonstrated excellent criterion based validity and reliability. The PILL-5 is the first validated patient reported outcome measure for pill dysphagia
Protective Effect of L-Carnitine and Coenzyme Q10 on CCl4-Induced Liver Injury in Rats
This study provides an information about the mechanisms of liver injury induced by CCl4, and determines the influence of administration of L-carnitine or/and CoQ10 as prophylactic agents against CCl4 deteriorative effect. The study was carried out on 80 adult male albino rats divided into eight groups, 10 animals each, as follows: four normal groups (control, treated with L-carnitine, treated with CoQ10, and treated with a combination of Lcarnitine and CoQ10) and four liver injury groups treated with CCl4 (control, treated with L-carnitine, treated with CoQ10, and treated with a combination of L-carnitine and CoQ10). Liver injury was induced by s.c. injection of a single dose of CCl4 (1 ml/kg). L-carnitine (50 mg/kg/day) was given i.p. for four successive days 24 hours before CCl4 injection, and CoQ10 (200 mg/kg) was given as a single i.p. dose 24 hours before CCl4 injection. Animals were sacrificed 24 hours after CCl4 injection, blood samples were withdrawn and liver tissue samples were homogenized. The levels of the following parameters were determined: hepatic reduced glutathione, serum ALT and AST, hepatic lipid peroxides, hepatic vitamin C, hepatic and serum total protein, serum albumin, serum sialic acid, serum nitrite, and serum and hepatic total LDH activities and LDH isoenzymes. The obtained data revealed that CCl4 injection produced a significant decrease in reduced glutathione content, vitamin C, total protein and albumin levels. However, there was a significant increase in serum ALT and AST activities, lipid peroxides, sialic acid, nitric oxide, serum and hepatic total LDH activities. On the other hand, groups treated with L-carnitine or/and CoQ10 prior to CCl4 injection showed an improvement in most parameters when compared with cirrhotic control group. It has been concluded that L-carnitine and coenzyme Q10 have a pronounced prophylactic effect against liver damage induced by halogenated alkanes such as carbon tetrachloride
Influence of Oscillating Packing Instrument on Microhardness of Bulk-Fill Composite: In Vitro Study
AIM: This study aimed to assess Vickers microhardness of Tetric EvoCeram Bulk Fill composite that was packed manually and using oscillating packing device.
MATERIALS AND METHODS: Two different packing techniques were applied on Tetric EvoCeram Bulk Fill composite. For each packing technique, ten specimens (6 mm in diameter and 4 mm height) were prepared using a black-shaded Teflon mold. The resin was inserted in a bulk increment either packed manually or using Compothixo oscillating device and then light-cured for 40 s. Microhardness was analyzed at the top and the bottom surfaces.
RESULTS: Overall, for both packing techniques, microhardness decreased significantly with the increase of depth. Tetric EvoCeram Bulk Fill composite when packed either manually or using oscillating device, did not show significant difference neither at the top surfaces of both applied techniques nor at the bottom surfaces of both applied techniques.
CONCLUSION: Different packing techniques did not influence the microhardness of Tetric EvoCeram Bulk Fill composite.
 
Efficacy of mirror therapy in improving hand function post flexor tendon repair
The aim of this study was to determine the efficacy of mirror therapy (MT) in improving the total active range of motion (AROM) of the affected finger, hand grip strength, and hand function in patients with flexor tendon repair (FTR) in zone II. The study was an open-label, parallel-group, randomized controlled trial. Thirty patients with zone II FTR, aged 20-45 years, were recruited and randomized into two equal groups: the MT group and the sham MT group. The intervention began in the fourth week post-operation, consisting of thirty minutes of MT or sham MT, three sessions per week for four weeks, in addition to the traditional physical therapy (PT) program. The total AROM of the interphalangeal (IP) joints of the affected fingers, hand grip strength, and hand function were assessed. After four weeks of intervention, the percentage change in total AROM was 25.7% in the MT group and 19.93% in the sham MT group. Additionally, hand grip strength and Michigan Hand Outcomes Questionnaire (MHQ) scores showed greater improvement in the MT group compared to the sham MT group (p < 0.05). Adding MT to the traditional PT program may be more effective than the traditional PT program alone in improving the AROM of the interphalangeal (IP) joints of the operated fingers, grip strength, and MHQ scores
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