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1.
Polymers (Basel) ; 16(5)2024 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-38475319

RESUMEN

Corrosion-related damage incurs significant capital costs in many industries. In this study, an anti-corrosive pigment was synthesized by modifying calcium carbonate with sodium alginate (SA), and smart self-healing coatings were synthesized by reinforcing the anti-corrosive pigments into a polyolefin matrix. Structural changes during the synthesis of the anti-corrosive pigment were examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Moreover, thermal gravimetric analysis confirmed the loading of the corrosion inhibitor, and electrochemical impedance spectroscopic analysis revealed a stable impedance value, confirming the improved corrosion resistance of the modified polyolefin coatings. The incorporation of the anticorrosive pigment into a polyolefin matrix resulted in improved pore resistance properties and capacitive behavior, indicating a good barrier property of the modified coatings. The formation of a protective film on the steel substrate reflected the adsorption of the corrosion inhibitor (SA) on the steel substrate, which further contributed to enhancing the corrosion resistance of the modified coatings. Moreover, the formation of the protective film was also analyzed by profilometry and elemental mapping analysis.

2.
Biomech Model Mechanobiol ; 23(2): 373-396, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38072897

RESUMEN

Using liver phantoms for mimicking human tissue in clinical training, disease diagnosis, and treatment planning is a common practice. The fabrication material of the liver phantom should exhibit mechanical properties similar to those of the real liver organ in the human body. This tissue-equivalent material is essential for qualitative and quantitative investigation of the liver mechanisms in producing nutrients, excretion of waste metabolites, and tissue deformity at mechanical stimulus. This paper reviews the mechanical properties of human hepatic tissues to develop liver-mimicking phantoms. These properties include viscosity, elasticity, acoustic impedance, sound speed, and attenuation. The advantages and disadvantages of the most common fabrication materials for developing liver tissue-mimicking phantoms are also highlighted. Such phantoms will give a better insight into the real tissue damage during the disease progression and preservation for transplantation. The liver tissue-mimicking phantom will raise the quality assurance of patient diagnostic and treatment precision and offer a definitive clinical trial data collection.


Asunto(s)
Diagnóstico por Imagen de Elasticidad , Humanos , Elasticidad , Hígado , Fantasmas de Imagen , Acústica
3.
Heliyon ; 9(11): e22071, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-38027785

RESUMEN

Research Experience programs (REPs) inspire students to pursue advanced degrees and shape their research career paths. Government and commercial organizations sponsor REPs to promote the capacity building of the country. In Qatar, the national youth is reported to show concerning participation in Science, Technology, Engineering, and Mathematics (STEM) disciplines at the K-12 level. However, none of the studies investigate these participation trends at the undergraduate level, especially in scientific research, which is deemed necessary for building a knowledge-based economy in Qatar. Therefore, to bridge this gap, the current study uses a quantitative approach to analyze the REP in Qatar through the participation data of 2455 undergraduate students. For this, statistical measures, including descriptive analysis, independent samples t-test, and Pearson's correlation analysis were used. Results indicated concerning trends in national student participation rate, implying underlying issues restricting their representation in undergraduate research activities. Also, statistically significant differences were found in student participation rates among students' gender and ethnic distributions. While female students demonstrated higher participation rates than males, national students showed lower participation than the non-nationals. Moreover, this low participation of national students suffered more drastically in STEM disciplines. Therefore, these findings determine the outlook for stakeholders and academic institutions in making meaningful educational decisions and envision synchronizing REPs at the university level, gauging measures to bolster the adjacent funding agencies and government organizations. Furthermore, being the first research addressing REPs in the Middle East region, this study has the potential to support educators in neighboring and other developing nations where STEM education is especially significant for human capacity building.

4.
Heliyon ; 9(2): e13477, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36814632

RESUMEN

Silicon/perovskite tandem devices are believed to be a favorite contender for improving cell performance over the theoretical maximum value of single-junction photovoltaic (PV) cells. The present study evaluates the design and optimization of four-terminal (4-T) mechanically stacked and optically coupled configurations using SCAPS (solar cell capacitance simulator). Low-cost, stable, and easily processed semitransparent carbon electrode-based perovskite solar cells (c-PSCs) without hole transport material (HTM) and highly efficient crystalline silicon (c-Si) PV cells were utilized as top and bottom cells, respectively. The wide bandgap multi-cation perovskite C s x ( F A 0.4 M A 0.6 ) 1 - x P b I 2.8 B r 0.2 and a low bandgap c-Si were employed as light-harvesting layers in the top and bottom cells, respectively. The impact of perovskite thickness and doping concentrations were examined and optimized for both tandem configurations. Under optimized conditions, thicknesses of 1000 nm and 1100 nm are the best values of the perovskite absorber layer for 4-T mechanically stacked and optically coupled arrangements, respectively. Likewise, 1 × 1017 cm-3 doping concentration of top cells revealed the highest performance in both structures. With these optimized parameters under tandem configurations, efficiency values of 28.38% and 29.34% were obtained in 4-T mechanically and optically coupled tandems, respectively. Results suggest that by optimizing perovskite thickness and doping concentration, the proposed designs using HTM-free c-PSCs could enhance device performance.

5.
Nanomaterials (Basel) ; 12(24)2022 Dec 11.
Artículo en Inglés | MEDLINE | ID: mdl-36558277

RESUMEN

NH3 is a highly harmful gas; when inhaled at levels that are too high for comfort, it is very dangerous to human health. One of the challenging tasks in research is developing ammonia sensors that operate at room temperature. In this study, we proposed a new design of an NH3 gas sensor that was comprised of two-dimensional (TMDs, mainly WS2 and MoS2) and PANI. The 2D-TMDs metal was successfully incorporated into the PANI lattice based on the results of XRD and SEM. The elemental EDX analysis results indicated that C, N, O, W, S and Mo were found in the composite samples. The bandgap of the materials decreased due to the addition of MoS2 and WS2. We also analyzed its structural, optical and morphological properties. When compared to MoS2 and PANI, the proposed NH3 sensor with the WS2 composite was found to have high sensitivity. The composite films also exhibited response and recovery times of 10/16 and 14/16 s. Therefore, the composite PANI/2D-TMDs is a suitable material for NH3 gas detection applications.

6.
Trials ; 23(1): 504, 2022 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-35710428

RESUMEN

BACKGROUND: Mobile health (mHealth) is increasingly advocated for diabetes management. It is unclear if mobile applications are effective in improving glycaemic control, clinical outcomes, quality of life and overall patient satisfaction in patients with type 2 diabetes (T2DM). A new mobile application was specifically built for people with T2DM with the help of the local expertise. The objective of the study was to evaluate the effectiveness of the mobile app. METHODS: The planned study is an ongoing open-label randomised controlled trial in which adults living with T2DM treated with insulin will be randomised 1:1 to the use of this diabetes application versus current standard care. The primary outcome will be the difference in mean HbA1c from baseline to 6 months. Other outcome measures include anthropometric measures, hypoglycaemic events, medication adjustments, number of clinical interactions and missed appointments and patient perceptions of their disease and diabetes self-management. The study will randomise 180 subjects for assessment of the primary outcome. DISCUSSION: We hypothesise that the diabetes-specific mobile application will improve glycaemic control, increase patient empowerment for self-management of diabetes and improve interaction between patients and healthcare providers. If the Qatar Diabetes Mobile Application Trial (QDMAT) demonstrates this, it will inform clinical services for the future self-management of T2DM. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03998267 . Registered on 26 June 2019.


Asunto(s)
Diabetes Mellitus Tipo 2 , Aplicaciones Móviles , Automanejo , Adulto , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Humanos , Qatar , Calidad de Vida , Ensayos Clínicos Controlados Aleatorios como Asunto , Automanejo/métodos
7.
Front Surg ; 9: 848565, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35310427

RESUMEN

Background: Currently, adrenalectomies are trending toward minimally invasive approach including robotic and laparoscopic surgery. We aimed to describe the clinical presentation and outcomes associated with the 3 different surgical approaches in patients who underwent adrenalectomy for adrenal mass at a single tertiary center. Methods: A retrospective descriptive observational study was conducted to include all patients who underwent surgical interventions for adrenal gland mass between 2004 and 2019. Patients were categorized into three groups according to the interventional approach (open, robotic vs. laparoscopic adrenalectomy) and data were analyzed and compared. Results: A total of 124 patients underwent adrenalectomies (61.3% robotic, 22.6% open, and 16.1% laparoscopic approach). Incidentally discovered adrenal mass was reported in 67% of patients, and hypertension was the most prevalent comorbidity (53%). The tendency for malignancy increased with increasing tumor size while the functioning tumors were more in the smaller tumor size. Larger tumors were more common in younger patients. The robotic approach showed shorter surgical intensive care and hospital length of stay. Patients in the open adrenalectomy group frequently presented with abdominal pain (p = 0.001), had more nonfunctional adrenal mass (p = 0.04), larger mean tumor size (p = 0.001), and were frequently operated on the right side (p = 0.03). There was no post-operative mortality; however, during follow-up, 8 patients died (3 open, 3 laparoscopic and, 2 robotic approach). The median follow-up was 746 days (range 7-5,840). Conclusions: The study explored the three surgical adrenalectomy approaches in a dedicated center for patients with adrenal pathology. It showed that robotic adrenalectomy could be safe and effective surgical approach for patients with benign functioning adrenal tumors of a diameter <6 cm. However, the choice of a surgical approach varies according to the adrenal mass presentation, patient fitness for surgery, type and sizes of the tumor, surgeon's experience, and hospital resources. Open surgery is considered the first choice for larger, ruptured adrenal tumor or malignancy. However, the recent restructuring of the surgical department resulted in selection bias in favor of the robotic surgery. Further studies are required to address the risk factors, selection criteria for appropriate management, cost, and quality of life.

8.
Materials (Basel) ; 14(16)2021 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-34442908

RESUMEN

The current work proposed the application of methylammonium lead iodide (MAPbI3) perovskite microrods toward photo resistor switches. A metal-semiconductor-metal (MSM) configuration with a structure of silver-MAPbI3(rods)-silver (Ag/MAPbI3/Ag) based photo-resistor was fabricated. The MAPbI3 microrods were prepared by adopting a facile low-temperature solution process, and then an independent MAPbI3 microrod was employed to the two-terminal device. The morphological and elemental compositional studies of the fabricated MAPbI3 microrods were performed using FESEM and EDS, respectively. The voltage-dependent electrical behavior and electronic conduction mechanisms of the fabricated photo-resistors were studied using current-voltage (I-V) characteristics. Different conduction mechanisms were observed at different voltage ranges in dark and under illumination. In dark conditions, the conduction behavior was dominated by typical trap-controlled charge transport mechanisms within the investigated voltage range. However, under illumination, the carrier transport is dominated by the current photogenerated mechanism. This study could extend the promising application of perovskite microrods in photo-induced resistor switches and beyond.

9.
Toxins (Basel) ; 13(4)2021 04 08.
Artículo en Inglés | MEDLINE | ID: mdl-33917988

RESUMEN

Mycotoxins are naturally occurring food toxins worldwide that can cause serious health effects. The measurement of mycotoxin biomarkers in biological fluids is needed to assess individuals' exposure. The aim of this study was to investigate the incidence of mycotoxins in the Qatari population. Serum samples from 412 adults and urinary samples from 559 adults were analyzed for the presence of mycotoxin biomarkers. Multimycotoxin approaches have been applied, using liquid chromatography mass spectrometry methods. Samples were further analyzed for the oxidative stress markers and compared with regard to the incidence of mycotoxins. The presence of mycotoxins was identified in 37% of serum samples and in less than 20% of urine samples. It was found that 88% of positive of the samples were positive for only one mycotoxin, while 12% of positive samples had two or more mycotoxins. Trichothecenes and zearalenone metabolites were most commonly detected mycotoxins, followed by aflatoxins, roquefortine C and mycophenolic acid. The presence of mycotoxins was found to positively correlate with oxidative stress markers. The obtained results illustrate the importance of mycotoxin biomonitoring studies in humans and the need to elucidate the underlying mechanisms of mycotoxin-induced toxicity.


Asunto(s)
Monitoreo Biológico , Contaminación de Alimentos , Micotoxinas/sangre , Micotoxinas/orina , Estrés Oxidativo , Adulto , Biomarcadores/sangre , Biomarcadores/orina , Carga Corporal (Radioterapia) , Cromatografía Líquida de Alta Presión , Daño del ADN , Femenino , Humanos , Masculino , Persona de Mediana Edad , Qatar , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masas en Tándem
10.
Drug Test Anal ; 13(7): 1341-1353, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33759363

RESUMEN

Ecdysteroids are of interest as potential sport performance enhancers, due to their anabolic effects. The current study aimed to analyze levels of the most abundant ecdysteroid, ecdysterone (20-hydroxyecdysone, 20-OHE) in easily available dietary supplements, and, outline an analytical strategy for its detection, and that, of its metabolites, (1) following administration of pure 20-OHE to uPA(+/+)-SCID mice with humanized liver, (2) in a human volunteer after ingestion of two supplements, one with a relatively low, and the other a high, concentration of 20-OHE, and, (3) to estimate the prevalence of use of 20-OHE in elite athletes (n = 1000). Of the 16 supplements tested, only five showed detectable levels of 20-OHE, with concentrations ranging from undetectable up to 2.3 mg per capsule. Urine of uPA(+/+)-SCID urine showed the presence of 20-OHE and its metabolite, 14 deoxy ecdysterone, within 24 hours (hr) of ingestion. In humans, both the parent and the metabolite were detectable within 2 to 5 hr of ingestion, with the metabolite being detectable for longer than the parent. After ingestion of a low dose supplement, the parent and metabolite were detectable for 70 and 48 hr, while following the higher dose it was 96 and 48 hr, respectively. Analysis of urines from athletes (n = 1000) confirmed four positives for 20-OHE, suggesting a prevalence of use of 0.4%. Prevalence of its use by elite athletes was relatively low, however, this needs to be confirmed in other populations, and with other related ecdysteroids.


Asunto(s)
Suplementos Dietéticos/análisis , Doping en los Deportes/prevención & control , Ecdisterona/orina , Detección de Abuso de Sustancias/métodos , Adulto , Animales , Atletas , Ecdisterona/análisis , Ecdisterona/metabolismo , Femenino , Humanos , Hígado/metabolismo , Masculino , Ratones , Ratones SCID , Prevalencia , Factores de Tiempo
11.
Sci Rep ; 11(1): 33, 2021 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-33420108

RESUMEN

Perovskite solar cells (PSCs) expressed great potentials for offering a feasible alternative to conventional photovoltaic technologies. 2D/3D hybrid PSCs, where a 2D capping layer is used over the 3D film to avoid the instability issues associated with perovskite film, have been reported with improved stabilities and high power conversion efficiencies (PCE). However, the profound analysis of the PSCs with prolonged operational lifetime still needs to be described further. Heading towards efficient and long-life PSCs, in-depth insight into the complicated degradation processes and charge dynamics occurring at PSCs' interfaces is vital. In particular, the Au/HTM/perovskite interface got a substantial consideration due to the quest for better charge transfer; and this interface is debatably the trickiest to explain and analyze. In this study, multiple characterization techniques were put together to understand thoroughly the processes that occur at the Au/HTM/perovskite interface. Inquest analysis using current-voltage (I-V), electric field induced second harmonic generation (EFISHG), and impedance spectroscopy (IS) was performed. These techniques showed that the degradation at the Au/HTM/perovskite interface significantly contribute to the increase of charge accumulation and change in impedance value of the PSCs, hence resulting in efficiency fading. The 3D and 2D/3D hybrid cells, with PCEs of 18.87% and 20.21%, respectively, were used in this study, and the analysis was performed over the aging time of 5000 h. Our findings propose that the Au/HTM/perovskite interface engineering is exclusively essential for attaining a reliable performance of the PSCs and provides a new perspective towards the stability enhancement for the perovskite-based future emerging photovoltaic technology.

12.
RSC Adv ; 11(46): 28735-28743, 2021 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-35478584

RESUMEN

The electrospinning technique has been successfully used to prepared micro-fibers of the poly(lactic acid)/polyaniline-zinc oxide (PLA/PANI-ZnO) composite. The polyaniline-zinc oxide (PANI-ZnO) nanocomposites are synthesized by hydrothermal and in situ polymerization methods. X-ray diffraction techniques are used to study the structural properties of the PLA/PANI-ZnO composite fibers and the PANI-ZnO nanocomposite. The average crystallite size of the PANI-ZnO nanocomposite is found to be 36 nm. The morphology and diameter of the composite fibers are analyzed by scanning electron microscopy (SEM). The average fiber diameter of the pure poly(lactic acid) (PLA) fiber is around 2.5 µm and that of the PLA/PANI-ZnO composite fiber is around 1.4 µm. Differential scanning calorimetry (DSC) provides the thermal properties of the PLA/PANI-ZnO composite fibers. The melting temperature (T m) for the pure PLA is observed at 149.3 °C, and it is shifted to 153.0 °C for the PLA/PANI-ZnO composite fibers. The enhanced thermal properties of the composite fibers are due to the interaction between the polymer and the nanoparticles. The water contact angle measurements probe the surface hydrophilicity of the PLA/PANI-ZnO composite fibers. The role of the PANI-ZnO nanocomposite on the sensing behavior of PLA fibers has also been investigated. The humidity sensing properties of the composite fiber based sensor are studied in the relative humidity (RH) range of 20-90% RH. The experimental results show that the composite fiber exhibited good response (85 s) and recovery (120 s) times. These results indicate that the one-dimensional (1D) fiber structure enhances the humidity sensing properties.

13.
Molecules ; 25(24)2020 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-33302578

RESUMEN

Despite the remarkable progress in perovskite solar cells (PSCs), their instability and rapid degradation over time still restrict their commercialization. A 2D capping layer has been proved to overcome the stability issues; however, an in-depth understanding of the complex degradation processes over a prolonged time at PSC interfaces is crucial for improving their stability. In the current work, we investigated the stability of a triple cation 3D ([(FA0.83MA0.17)Cs0.05]Pb(I0.83Br0.17)3) and 2D/3D PSC fabricated by a layer-by-layer deposition technique (PEAI-based 2D layer over triple cation 3D perovskite) using a state-of-art characterization technique: electrochemical impedance spectroscopy (EIS). A long-term stability test over 24 months was performed on the 3D and 2D/3D PSCs with an initial PCE of 18.87% and 20.21%, respectively, to suggest a more practical scenario. The current-voltage (J-V) and EIS results showed degradation in both the solar cell types; however, a slower degradation rate was observed in 2D/3D PSCs. Finally, the quantitative analysis of the key EIS parameters affected by the degradation in 3D and 2D/3D PSCs were discussed.


Asunto(s)
Compuestos de Calcio/química , Espectroscopía Dieléctrica , Óxidos/química , Energía Solar , Titanio/química
14.
Talanta ; 219: 121361, 2020 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-32887084

RESUMEN

Porous microstructure materials are considered good candidates for the development of highly sensitive and fast humidity sensors. In this regard, we prepared polyaniline (PANI) decorated Cu-ZnS porous microsphere structures (PMSs) for the fabrication of humidity sensors. PANI coated Cu-ZnS PMSs were synthesized by a hydrothermal method and in situ polymerization process. The synthesized PMSs were characterized by different techniques to study the structural, morphological and surface absorption properties. Several compositions for the PANI/Cu-ZnS PMS were investigated, which were then compared with pure PANI. The experimental observations demonstrate that a PANI/1%Cu-ZnS PMS has better sensitivity, fast response and good stability compared to pure PANI and other PANI/CuZnS compositions. Finally, a PANI/1% Cu-ZnS PMS was found to be optimized for humidity sensors due to its well distributed roughness, porosity and hydrophilicity. The average response and recovery times for PANI/1% Cu-ZnS were found to be 42 s and 24 s, respectively, which outperform recent results.

15.
Nanomaterials (Basel) ; 10(9)2020 Aug 20.
Artículo en Inglés | MEDLINE | ID: mdl-32825347

RESUMEN

The future photovoltaic technologies based on perovskite materials are aimed to build low tech, truly economical, easily fabricated, broadly deployable, and trustworthy solar cells. Hole transport material (HTM) free perovskite solar cells (PSCs) are among the most likely architectures which hold a distinctive design and provide a simple way to produce large-area and cost-effective manufacture of PSCs. Notably, in the monolithic scheme of the HTM-free PSCs, all layers can be printed using highly reproducible and morphology-controlled methods, and this design has successfully been demonstrated for industrial-scale fabrication. In this review article, we comprehensively describe the recent advancements in the different types of mesoporous (nanostructured) and planar HTM-free PSCs. In addition, the effect of various nanostructures and mesoporous layers on their performance is discussed using the electrochemical impedance spectroscopy (EIS) technique. We bring together the different perspectives that researchers have developed to interpret and analyze the EIS data of the HTM-free PSCs. Their analysis using the EIS tool, the limitations of these studies, and the future work directions to overcome these limitations to enhance the performance of HTM-free PSCs are comprehensively considered.

16.
RSC Adv ; 10(45): 26604-26612, 2020 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-35515812

RESUMEN

Polyaniline (PANI)/Cu-ZnS composites with porous microspheres are prepared by a hydrothermal and in situ polymerization method. The structural, optical, and morphological properties are characterized by X-ray powder diffraction, FTIR, UV-vis, scanning electron microscope, transmission electron microscope. The XRD results confirmed that the PANI/Cu-ZnS composite is formed. The morphological analyses exhibited that the PANI/Cu-ZnS composite comprises the porous microspherical structures. The emission peaks obtained in photoluminescence spectra confirm the presence of surface defects in the prepared composite. The UV-DRS study shows that the bandgap of the samples is found to decrease for the PANI/Cu-ZnS composite compared to the pure Cu-ZnS sample. The calculated band gap (E g) value of PANI/Cu-ZnS composite is 2.47 eV. Furthermore, the fabricated gas sensor based on PANI/Cu-ZnS can perform at room temperature and exhibits good gas sensing performance toward CO2 gas. In particular, PANI/Cu-ZnS sensor shows good response (31 s) and recovery time (23 s) upon exposure to CO2 gas. The p/n heterojunction, surface defects, and porous nature of the PANI/Cu-ZnS composite microsphere enhanced sensor performance.

17.
RSC Adv ; 9(22): 12496-12506, 2019 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-35515869

RESUMEN

This research work presents the fabrication of polyaniline (PANI) and graphene-polyaniline (graphene-PANI) nanocomposite-coated polystyrene (PS) nanofibre mats, as well as their application in flexible and highly sensitive gas sensors. The surface morphology of the flexible films is investigated using a number of techniques. The profilometry studies confirmed that the electrospun fibres are evenly distributed over a large surface area and there was no visible difference between coated and uncoated fibres. The SEM morphology studies revealed that a nanocomposite consisting of 10 nm PANI nanofibres and graphene forms a uniform coating around 3 µm diameter PS fiber. AFM showed differences in the 3D surface topography between plain PS nanofibres and coated ones, which showed an increased roughness. Moreover, conductive AFM has indicated an increase in the electrical current distribution from picoamperes to nanoamperes of the PS samples coated with PANI and graphene-PANI because of the applied voltage to the AFM tip that contacted the sample surface. The chemical properties of all the samples are analysed by Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD), which revealed the presence of chemical interactions between the nanocomposites and the polymeric backbones. The TGA study indicated that graphene-PANI coated fibres have the highest thermal stability compared to the pure fibres. The addition of the nanocomposite layer to the PS fibre significantly increased the electrical conductivity. Therefore, nanocomposite-coated flexible membranes are used to fabricate carbon dioxide gas sensors (sensing range: 20-100 ppm). Due to the higher surface area of the nanocomposite coated fibre the availability of adsorption area is also higher, which leads to an increase in sensitivity to carbon dioxide gas. The sensitivity increases with the increase in gas concentration. The average response time of the sensor is calculated to be 65 seconds, with good and uniform repeatability.

18.
Curr Vasc Pharmacol ; 17(4): 354-364, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-29359671

RESUMEN

BACKGROUND: We hypothesized that perioperative HbA1c influenced the pattern and outcomes of Lower Extremity Amputation (LEA). METHODS: A retrospective analysis was conducted for all patients who underwent LEA between 2000 and 2013. Patients were categorized into 5 groups according to their perioperative HbA1c values [Group 1 (<6.5%), Group 2 (6.5-7.4%), Group 3 (7.5-8.4%), Group 4 (8.5-9.4%) and Group 5 (≥9.5%)]. We identified 848 patients with LEA; perioperative HbA1c levels were available in 547 cases (Group 1: 18.8%, Group 2: 17.7%, Group 3: 15.0%, Group 4: 13.5% and Group 5: 34.9%). Major amputation was performed in 35%, 32%, 22%, 10.8% and 13.6%, respectively. RESULTS: The overall mortality was 36.5%; of that one quarter occurred during the index hospitalization. Mortality was higher in Group 1 (57.4%) compared with Groups 2-5 (46.9%, 38.3%, 36.1% and 31.2%, respectively, p=0.001). Cox regression analysis showed that poor glycemic control (Group 4 and 5) had lower risk of mortality post-LEA [hazard ratio 0.57 (95% CI 0.35-0.93) and hazard ratio 0.46 (95% CI 0.31-0.69)]; this mortality risk persisted even after adjustment for age and sex but was statistically insignificant. The rate of LEA was greater among poor glycemic control patients; however, the mortality was higher among patients with tight control. CONCLUSION: The effects of HbA1c on the immediate and long-term LEA outcomes and its therapeutic implications need further investigation.


Asunto(s)
Amputación Quirúrgica/mortalidad , Glucemia/metabolismo , Diabetes Mellitus/sangre , Hemoglobina Glucada/metabolismo , Extremidad Inferior/irrigación sanguínea , Enfermedad Arterial Periférica/cirugía , Adulto , Anciano , Amputación Quirúrgica/efectos adversos , Biomarcadores/sangre , Glucemia/efectos de los fármacos , Diabetes Mellitus/diagnóstico , Diabetes Mellitus/tratamiento farmacológico , Diabetes Mellitus/mortalidad , Femenino , Humanos , Hipoglucemiantes/uso terapéutico , Incidencia , Masculino , Persona de Mediana Edad , Enfermedad Arterial Periférica/diagnóstico , Enfermedad Arterial Periférica/mortalidad , Prevalencia , Qatar/epidemiología , Estudios Retrospectivos , Medición de Riesgo , Factores de Riesgo , Factores de Tiempo , Resultado del Tratamiento
19.
Ann Vasc Surg ; 41: 46-55, 2017 May.
Artículo en Inglés | MEDLINE | ID: mdl-28238919

RESUMEN

BACKGROUND: To investigate the clinical characteristics, surgical interventions, and outcomes of arteriovenous fistula (AVF) aneurysms, we retrospectively analyzed patients on regular hemodialysis (HD). METHODS: We conducted a cohort study of all patients with HD access who presented with AVF aneurysms and underwent operative procedures over a 11-year period. Patients' demographics, comorbidities, vascular access characteristics, management of aneurysms, complications, and outcomes were analyzed. RESULTS: Of the 700 end-stage renal failure patients, 530 patients were maintained on HD (130 through PermCath and 400 through AV access in terms of AVF and arteriovenous graft). We identified 129 patients who developed AV aneurysms, and 40 of them required surgical interventions (24 men and 16 women) with a mean age of 58 ± 14.6 years. The 40 patients who developed AVF aneurysms underwent 43 surgical interventions. The majority of aneurysms were presented with thinning and ulceration (82.5%) of the overlying skin. Thirty-four patients had true aneurysms and 6 had pseudoaneurysms. The aneurysmal AVF comprised 26 brachiocephalic fistulas, 9 radiocephalic fistulas, 3 brachial artery grafts, 1 ulnar-basilic fistula, and 1 Fem-Fem graft at presentation. Patients were treated mainly with ligation (13; 32.5%), excision and repair with graft interposition (15; 37.5%) or vein interposition (11; 27.5%), and end-to-end AVF (1; 2.5%). The median follow-up postsurgery duration was 53 months (range 1-192) and the median duration from fistula creation to the surgical intervention was 52 months (range 4-182). On follow-up, 34 patients continued on HD, while 5 underwent renal transplantation and 1 shifted to peritoneal dialysis. The overall all-cause mortality rate was 37.5% and the leading causes of mortality were sepsis/pneumonia (60%), myocardial infarction, and heart failure (40%). CONCLUSIONS: In HD patients, the rate of AVF aneurysmal formation is high with a significant rate of morbidity and mortality. Therefore, timely and appropriate evaluation and surgical intervention are crucial.


Asunto(s)
Aneurisma/cirugía , Derivación Arteriovenosa Quirúrgica/efectos adversos , Fallo Renal Crónico/terapia , Diálisis Renal , Extremidad Superior/irrigación sanguínea , Adulto , Anciano , Aneurisma/diagnóstico por imagen , Aneurisma/etiología , Aneurisma/mortalidad , Derivación Arteriovenosa Quirúrgica/mortalidad , Bases de Datos Factuales , Femenino , Humanos , Fallo Renal Crónico/diagnóstico , Fallo Renal Crónico/mortalidad , Masculino , Persona de Mediana Edad , Qatar , Diálisis Renal/efectos adversos , Diálisis Renal/mortalidad , Estudios Retrospectivos , Factores de Riesgo , Factores de Tiempo , Resultado del Tratamiento
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