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1.
Transl Vis Sci Technol ; 13(4): 14, 2024 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-38591946

RESUMEN

Purpose: Retinal sensitivity is frequently listed as an end point in clinical trials, often with long working practices. The purpose of this methods study was to provide a new workflow and reduced test time for in-depth characterization of retinal sensitivity. Methods: A workflow for the MP3-S microperimeter with detailed functional characterization of the retina under photopic, mesopic, and scotopic conditions was evaluated. Grids of 32 and 28 test positions for photopic/mesopic and scotopic, respectively, were tested in 12 healthy individuals and compared with an established 68-point grid for test time, mean sensitivity (MS), and bivariate contour ellipse area (BCEA). Results: The mean test time (range; ±SD) was 10.5 minutes (8.4-14.9; ±2.0) in the 68-point grid and 4.3 minutes (3.8-5.0; ±0.4) in the 32-point grid, which was significantly different (P < 0.0001). The mean of difference in test time (±SD; 95% confidence interval) was 6.1 minutes (±2.0; 4.6-7.6). MS and BCEA were significantly correlated between grids (r = 0.89 and 0.74; P = 0.0005 and 0.014, respectively). Mean test time of subjects who underwent the full protocol (n = 4) was 2.15 hours. Conclusions: The protocol suggested herein appears highly feasible with in-depth characterization of retinal function under different testing conditions and in a short test time. Translational Relevance: The protocol described herein allows for characterization of the retina under different testing conditions and in a short test time, which is relevant due to its potential for patient prognostication and follow-up in clinical settings and also given its increasing role as a clinical trial end point.


Asunto(s)
Retina , Humanos , Retina/fisiología , Flujo de Trabajo , Determinación de Punto Final , Ensayos Clínicos como Asunto
2.
Am J Ophthalmol ; 263: 1-10, 2024 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-38364953

RESUMEN

PURPOSE: To analyze the clinical characteristics, natural history, and genetics of PDE6B-associated retinal dystrophy. DESIGN: Retrospective, observational cohort study. METHODS: Review of medical records and retinal imaging, including fundus autofluorescence (FAF) imaging and spectral-domain optical coherence tomography (SD-OCT) of patients with molecularly confirmed PDE6B-associated retinal dystrophy in a single tertiary referral center. Genetic results were reviewed, and the detected variants were assessed. RESULTS: Forty patients (80 eyes) were identified and evaluated longitudinally. The mean age (±SD, range) was 42.1 years (± 19.0, 10-86) at baseline, with a mean follow-up time of 5.2 years. Twenty-nine (72.5%) and 27 (67.5%) patients had no or mild visual acuity impairment at baseline and last visit, respectively. Best-corrected visual acuity (BCVA) was 0.56 ± 0.72 LogMAR (range -0.12 to 2.80) at baseline and 0.63 ± 0.73 LogMAR (range 0.0-2.80) at the last visit. BCVA was symmetrical in 87.5% of patients. A hyperautofluorescent ring was observed on FAF in 48 and 46 eyes at baseline and follow-up visit, respectively, with a mean area of 7.11 ± 4.13 mm2 at baseline and mean of 6.13 ± 3.62 mm2 at the follow-up visit. Mean horizontal ellipsoid zone width at baseline was 1946.1 ± 917.2 µm, which decreased to 1763.9 ± 827.9 µm at follow-up. Forty-four eyes had cystoid macular edema at baseline (55%), and 41 eyes (51.3%) at follow-up. There were statistically significant changes during the follow-up period in terms of BCVA and the ellipsoid zone width. Genetic analysis identified 43 variants in the PDE6B gene, including 16 novel variants. CONCLUSIONS: This study details the natural history of PDE6B-retinopathy in the largest cohort to date. Most patients had mild to no BCVA loss, with slowly progressive disease, based on FAF and OCT metrics. There is a high degree of disease symmetry and a wide window for intervention.

3.
Genes (Basel) ; 15(2)2024 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-38397231

RESUMEN

Background: Undifferentiated pleomorphic sarcoma of bone (UPSb) is a rare primary bone sarcoma that lacks a specific line of differentiation. Distinguishing between UPSb and other malignant bone sarcomas, including dedifferentiated chondrosarcoma and osteosarcoma, is challenging due to their overlapping features. We have previously identified that UPSb tumours have elevated mRNA levels of Fibroblast Growth Factor 23 (FGF23) transcripts compared to other sarcomas including osteosarcoma. In the present study, we evaluated the specificity and practicality of FGF23 immunoreactivity as a specific diagnostic tool to differentiate UPSb tumours from osteosarcomas and dedifferentiated chondrosarcomas. Methods: A total of 10 UPSb, 10 osteosarcoma, and 10 dedifferentiated chondrosarcoma cases (all high-grade), were retrieved and immunohistochemistry for FGF23 was performed. Results: FGF23 protein was expressed at high levels in 80-90% of undifferentiated pleomorphic sarcoma of the bone cases, whereas it was expressed at significantly lower levels in dedifferentiated chondrosarcoma and osteosarcoma cases. A semiquantitative analysis, considering the intensity of immunoreactivity, confirmed significantly elevated FGF23 expression levels in UPSb tissues compared to those observed in osteosarcoma and dedifferentiated chondrosarcoma tissues. Conclusions: The results we present here suggest that FGF23 immunohistochemistry may be a useful tool to aid in differentiating UPSb from morphologically similar malignant bone sarcomas, especially in situations where sampling is restricted and there is limited clinical information available.


Asunto(s)
Neoplasias Óseas , Condrosarcoma , Factor-23 de Crecimiento de Fibroblastos , Osteosarcoma , Sarcoma , Humanos , Neoplasias Óseas/diagnóstico , Neoplasias Óseas/genética , Condrosarcoma/diagnóstico , Condrosarcoma/genética , Condrosarcoma/metabolismo , Osteosarcoma/diagnóstico , Osteosarcoma/genética , Sarcoma/diagnóstico , Sarcoma/genética , Sarcoma/patología , Factor-23 de Crecimiento de Fibroblastos/metabolismo
4.
Sensors (Basel) ; 23(6)2023 Mar 09.
Artículo en Inglés | MEDLINE | ID: mdl-36991687

RESUMEN

In deeper layers, ResNet heavily depends on skip connections and Relu. Although skip connections have demonstrated their usefulness in networks, a major issue arises when the dimensions between layers are not consistent. In such cases, it is necessary to use techniques such as zero-padding or projection to match the dimensions between layers. These adjustments increase the complexity of the network architecture, resulting in an increase in parameter number and a rise in computational costs. Another problem is the vanishing gradient caused by utilizing Relu. In our model, after making appropriate adjustments to the inception blocks, we replace the deeper layers of ResNet with modified inception blocks and Relu with our non-monotonic activation function (NMAF). To reduce parameter number, we use symmetric factorization and 1×1 convolutions. Utilizing these two techniques contributed to reducing the parameter number by around 6 M parameters, which has helped reduce the run time by 30 s/epoch. Unlike Relu, NMAF addresses the deactivation problem of the non-positive number by activating the negative values and outputting small negative numbers instead of zero in Relu, which helped in enhancing the convergence speed and increasing the accuracy by 5%, 15%, and 5% for the non-noisy datasets, and 5%, 6%, 21% for non-noisy datasets.

5.
J Health Organ Manag ; ahead-of-print(ahead-of-print)2023 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-36710262

RESUMEN

PURPOSE: This study takes a divergent approach to exploring which construct is more predictive of patient satisfaction (SAT) in a service dominant economy within the context of a healthcare setting. DESIGN/METHODOLOGY/APPROACH: Applying a critical analysis of literature, a service value (SV) model for customer SAT is proposed in this study, which is validated and confirmed with survey data from outpatients at Moorfields Eye Hospital - a world class specialist hospital based in the UK. FINDINGS: Quality of service had the strongest impact on SV but SV had the strongest impact and mediation effect on patient SAT. RESEARCH LIMITATIONS/IMPLICATIONS: The study concludes that since SV rather than quality of service is more predictive of patient SAT, health service providers should focus more on SV in addition to quality of service, if they are to meet the dynamic expectations of their patients. PRACTICAL IMPLICATIONS: Health service providers should focus more on SV in addition to quality of service, if they are to meet the dynamic expectations of their patients. SOCIAL IMPLICATIONS: This poses a strong argument in favour of a paradigm shift in focus from quality of service-based model to service value-based model for greater patient satisfaction. ORIGINALITY/VALUE: This is the first study exploring the inter-relationship of four constructs of patient SAT within the context of a leading major UK healthcare hospital service.


Asunto(s)
Satisfacción del Paciente , Calidad de la Atención de Salud , Humanos , Hospitales , Atención al Paciente , Pacientes
6.
Ophthalmology ; 130(4): 413-422, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36423731

RESUMEN

PURPOSE: To review and describe in detail the clinical course, functional and anatomic characteristics of RP2-associated retinal degeneration. DESIGN: Retrospective case series. PARTICIPANTS: Male participants with disease-causing variants in the RP2 gene. METHODS: Review of all case notes and results of molecular genetic testing, retinal imaging (fundus autofluorescence [FAF] imaging, OCT), and electrophysiology assessment. MAIN OUTCOME MEASURES: Molecular genetic testing, clinical findings including best-corrected visual acuity (BCVA), qualitative and quantitative retinal imaging analysis, and electrophysiology parameters. RESULTS: Fifty-four molecularly confirmed patients were identified from 38 pedigrees. Twenty-eight disease-causing variants were identified, with 20 not previously clinically characterized. Fifty-three patients (98.1%) presented with retinitis pigmentosa. The mean age of onset (range ± standard deviation [SD]) was 9.6 years (1-57 ± 9.2 years). Forty-four patients (91.7%) had childhood-onset disease, with mean age of onset of 7.6 years. The most common first symptom was night blindness (68.8%). Mean BCVA (range ± SD) was 0.91 logarithm of the minimum angle of resolution (logMAR) (0-2.7 ± 0.80) and 0.94 logMAR (0-2.7 ± 0.78) for right and left eyes, respectively. On the basis of the World Health Organization visual impairment criteria, 18 patients (34%) had low vision. The majority (17/22) showed electroretinogram (ERG) evidence of a rod-cone dystrophy. Pattern ERG P50 was undetectable in all but 2 patients. A range of FAF findings was observed, from normal to advanced atrophy. There were no statistically significant differences between right and left eyes for ellipsoid zone width (EZW) and outer nuclear layer (ONL) thickness. The mean annual rate of EZW loss was 219 µm/year, and the mean annual decrease in ONL thickness was 4.93 µm/year. No patient with childhood-onset disease had an identifiable ellipsoid zone (EZ) after the age of 26 years at baseline or follow-up. Four patients had adulthood-onset disease and a less severe phenotype. CONCLUSIONS: This study details the clinical phenotype of RP2 retinopathy in a large cohort. The majority presented with early-onset severe retinal degeneration, with early macular involvement and complete loss of the foveal photoreceptor layer by the third decade of life. Full-field ERGs revealed rod-cone dystrophy in the vast majority, but with generalized (peripheral) cone system involvement of widely varying severity in the first 2 decades of life. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.


Asunto(s)
Distrofias de Conos y Bastones , Degeneración Retiniana , Humanos , Masculino , Distrofias de Conos y Bastones/diagnóstico , Distrofias de Conos y Bastones/genética , Electrorretinografía , Proteínas de Unión al GTP , Proteínas de la Membrana , Biología Molecular , Retina , Degeneración Retiniana/diagnóstico , Degeneración Retiniana/genética , Estudios Retrospectivos , Tomografía de Coherencia Óptica/métodos , Lactante , Preescolar , Niño , Adolescente , Adulto Joven , Adulto , Persona de Mediana Edad
7.
Nanomaterials (Basel) ; 12(3)2022 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-35159682

RESUMEN

Today, the optimal use of non-renewable energy sources, reducing pollution, and increasing the efficiency of power-generating cycles are of particular importance. There are several ways to increase the efficiency of gas turbines; one that has recently attracted attention is to use an intercooler. However, the efficiency of the heat exchanger used in intercoolers depends on the type of heat exchanger, the characteristics of the operating fluid and the thermal boundary layers, and the pump speed. Improving the thermophysical properties of the working fluid is a passive method of increasing heat transfer, which has attracted the attention of those researching engineering applications. The current review addresses the latest methods of improving gas turbine efficiency using nanofluids and includes experimental and numerical studies. First, the general principles governing turbines are described, then the commonly used types of heat exchangers are introduced. Finally, studies on the use of nanofluids in heat exchangers are reviewed. The technology of producing nanoparticles that can be used in heat exchangers is also discussed. This review article can provide the reader with comprehensive information on making nanofluids and using them in heat exchangers used as intercoolers.

8.
Nanomaterials (Basel) ; 12(3)2022 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-35159702

RESUMEN

In this study, the thermophysical properties and dispersion stability of graphene-based nanofluids were investigated. This was conducted to determine the influence of fabrication temperature, nanomaterial concentration, and surfactant ratio on the suspension effective properties and stability condition. First, the nanopowder was characterized in terms of crystalline structure and size, morphology, and elemental content. Next, the suspensions were produced at 10 °C to 70 °C using different concentrations of surfactants and nanomaterials. Then, the thermophysical properties and physical stability of the nanofluids were determined. The density of the prepared nanofluids was found to be higher than their base fluid, but this property showed a decrease with the increase in fabrication temperature. Moreover, the specific heat capacity showed very high sensitivity toward the graphene and surfactant concentrations, where 28.12% reduction in the property was achieved. Furthermore, the preparation temperature was shown to be the primary parameter that effects the nanofluid viscosity and thermal conductivity, causing a maximum reduction of ~4.9% in viscosity and ~125.72% increase in thermal conductivity. As for the surfactant, using low concentration demonstrated a short-term stabilization capability, whereas a 1:1 weight ratio of graphene to surfactant and higher caused the dispersion to be physically stable for 45 consecutive days. The findings of this work are believed to be beneficial for further research investigations on thermal applications of moderate temperatures.

9.
Nanomaterials (Basel) ; 11(11)2021 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-34835716

RESUMEN

Glasses, which date back to about 2500 BC, originated in Mesopotamia and were later brought to Egypt in approximately 1450 BC. In contrast to the long-range order materials (crystalline materials), the atoms and molecules of glasses, which are noncrystalline materials (short-range order) are not organized in a definite lattice pattern. Metallic glassy materials with amorphous structure, which are rather new members of the advanced materials family, were discovered in 1960. Due to their amorphous structure, metallic glassy alloys, particularly in the supercooled liquid region, behave differently when compared with crystalline alloys. They reveal unique and unusual mechanical, physical, and chemical characteristics that make them desirable materials for many advanced applications. Although metallic glasses can be produced using different techniques, many of these methods cannot be utilized to produce amorphous alloys when the system has high-melting temperature alloys (above 1500 °C) and/or is immiscible. As a result, such constraints may limit the ability to fabricate high-thermal stable metallic glassy families. The purpose of this research is to fabricate metallic glassy (Zr70Ni25Al5)100-xWx (x; 0, 2, 10, 20, and 35 at. %) by cold rolling the constituent powders and then mechanically alloying them in a high-energy ball mill. The as-prepared metallic glassy powders demonstrated high-thermal stability and glass forming ability, as evidenced by a broad supercooled liquid region and a high crystallization temperature. The glassy powders were then consolidated into full-dense bulk metallic glasses using a spark plasma sintering technique. This consolidation method did not result in the crystallization of the materials, as the consolidated buttons retained their short-range order fashion. Additionally, the current work demonstrated the capability of fabricating very large bulk metallic glassy buttons with diameters ranging from 20 to 50 mm. The results indicated that the microhardness of the synthesized metallic glassy alloys increased as the W concentration increased. As far as the authors are aware, this is the first time this metallic glassy system has been reported.

10.
Nanomaterials (Basel) ; 11(10)2021 Sep 24.
Artículo en Inglés | MEDLINE | ID: mdl-34684925

RESUMEN

Throughout human history, any society's capacity to fabricate and refine new materials to satisfy its demands has resulted in advances to its performance and worldwide standing. Life in the twenty-first century cannot be predicated on tiny groupings of materials; rather, it must be predicated on huge families of novel elements dubbed "advanced materials". While there are several approaches and strategies for fabricating advanced materials, mechanical milling (MM) and mechanochemistry have garnered much interest and consideration as novel ways for synthesizing a diverse range of new materials that cannot be synthesized by conventional means. Equilibrium, nonequilibrium, and nanocomposite materials can be easily obtained by MM. This review article has been addressed in part to present a brief history of ball milling's application in the manufacture of a diverse variety of complex and innovative materials during the last 50 years. Furthermore, the mechanism of the MM process will be discussed, as well as the factors affecting the milling process. Typical examples of some systems developed at the Nanotechnology and Applications Program of the Kuwait Institute for Scientific Research during the last five years will be presented in this articles. Nanodiamonds, nanocrystalline hard materials (e.g., WC), metal-matrix and ceramic matrix nanocomposites, and nanocrystalline titanium nitride will be presented and discussed. The authors hope that the article will benefit readers and act as a primer for engineers and researchers beginning on material production projects using mechanical milling.

11.
Nanomaterials (Basel) ; 11(9)2021 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-34578617

RESUMEN

Coolants play a major role in the performance of heat exchanging systems. In a marine gas turbine engine, an intercooler is used to reduce the compressed gas temperature between the compressor stages. The thermophysical properties of the coolant running within the intercooler directly influence the level of enhancement in the performance of the unit. Therefore, employing working fluids of exceptional thermal properties is beneficial for improving performance in such applications, compared to conventional fluids. This paper investigates the effect of utilizing nanofluids for enhancing the performance of a marine gas turbine intercooler. Multi-walled carbon nanotubes (MWCNTs)-water with nanofluids at 0.01-0.10 vol % concentration were produced using a two-step controlled-temperature approach ranging from 10 °C to 50 °C. Next, the thermophysical properties of the as-prepared suspensions, such as density, thermal conductivity, specific heat capacity, and viscosity, were characterized. The intercooler performance was then determined by employing the measured data of the MWCNTs-based nanofluids thermophysical properties in theoretical formulae. This includes determining the intercooler effectiveness, heat transfer rate, gas outlet temperature, coolant outlet temperature, and pumping power. Finally, a comparison between a copper-based nanofluid from the literature with the as-prepared MWCNTs-based nanofluid was performed to determine the influence of each of these suspensions on the intercooler performance.

12.
Int J Neonatal Screen ; 7(3)2021 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-34449519

RESUMEN

Kuwait is a small Arabian Gulf country with a high rate of consanguinity and where a national newborn screening program was expanded in October 2014 to include a wide range of endocrine and metabolic disorders. A retrospective study conducted between January 2015 and December 2020 revealed a total of 304,086 newborns have been screened in Kuwait. Six newborns were diagnosed with classic homocystinuria with an incidence of 1:50,000, which is not as high as in Qatar but higher than the global incidence. Molecular testing for five of them has revealed three previously reported pathogenic variants in the CBS gene, c.969G>A, p.(Trp323Ter); c.982G>A, p.(Asp328Asn); and the Qatari founder variant c.1006C>T, p.(Arg336Cys). This is the first study to review the screening of newborns in Kuwait for classic homocystinuria, starting with the detection of elevated blood methionine and providing a follow-up strategy for positive results, including plasma total homocysteine and amino acid analyses. Further, we have demonstrated an increase in the specificity of the current newborn screening test for classic homocystinuria by including the methionine to phenylalanine ratio along with the elevated methionine blood levels in first-tier testing. Here, we provide evidence that the newborn screening in Kuwait has led to the early detection of classic homocystinuria cases and enabled the affected individuals to lead active and productive lives.

13.
Molecules ; 26(16)2021 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-34443549

RESUMEN

Hydrogen has been receiving great attention as an energy carrier for potential green energy applications. Hydrogen storage is one of the most crucial factors controlling the hydrogen economy and its future applications. Amongst the several options of hydrogen storage, light metal hydrides, particularly nanocrystalline magnesium hydride (MgH2), possess attractive properties, making them desired hydrogen storage materials. The present study aimed to improve the hydrogen storage properties of MgH2 upon doping with different concentrations of zirconium carbide (ZrC) nanopowders. Both MgH2 and ZrC were prepared using reactive ball milling and high-energy ball milling techniques, respectively. The as-prepared MgH2 powder was doped with ZrC (2, 5, and 7 wt%) and then high-energy-ball-milled for 25 h. During the ball milling process, ZrC powders acted as micro-milling media to reduce the MgH2 particle size to a minimal value that could not be obtained without ZrC. The as-milled nanocomposite MgH2/ZrC powders consisted of fine particles (~0.25 µm) with a nanosized grain structure of less than 7 nm. Besides, the ZrC agent led to the lowering of the decomposition temperature of MgH2 to 287 °C and the reduction in its apparent activation energy of desorption to 69 kJ/mol. Moreover, the hydrogenation/dehydrogenation kinetics of the nanocomposite MgH2/ZrC system revealed a significant improvement, as indicated by the low temperature and short time required to achieve successful uptake and release processes. This system possessed a high capability to tackle a long continuous cycle lifetime (1400 h) at low temperatures (225 °C) without showing serious degradation in its storage capacity.

14.
Nanomaterials (Basel) ; 11(8)2021 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-34443970

RESUMEN

Non-metallic oxide nanofluids have recently attracted interest in pool boiling heat transfer (PBHT) studies. Research work on carbon and silica-based nanofluids is now being reported frequently by scholars. The majority of these research studies showed improvement in PBHT performance. The present study reports an investigation on the PBHT characteristics and performance of water-based silica nanofluids in the nucleate boiling region. Sonication-aided stable silica nanofluids with 0.0001, 0.001, 0.01, and 0.1 particle concentrations were prepared. The stability of nanofluids was detected and confirmed via visible light absorbance and zeta potential analyses. The PBHT performance of nanofluids was examined in a customized boiling pool with a flat heating surface. The boiling characteristics, pool boiling heat transfer coefficient (PBHTC), and critical heat flux (CHF) were analyzed. The effects of surface wettability, contact angle, and surface roughness on heat transfer performance were investigated. Bubble diameter and bubble departure frequency were estimated using experimental results. PBHTC and CHF of water have shown an increase due to the nanoparticle inclusion, where they have reached a maximum improvement of ≈1.33 times over that of the base fluid. The surface wettability of nanofluids was also enhanced due to a decrease in boiling surface contact angle from 74.1° to 48.5°. The roughness of the boiling surface was reduced up to 1.5 times compared to the base fluid, which was due to the nanoparticle deposition on the boiling surface. Such deposition reduces the active nucleation sites and increases the thermal resistance between the boiling surface and bulk fluid layer. The presence of the dispersed nanoparticles caused a lower bubble departure frequency by 2.17% and an increase in bubble diameter by 4.48%, which vigorously affects the pool boiling performance.

15.
Nanomaterials (Basel) ; 11(6)2021 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-34205801

RESUMEN

Nanofluids have opened the doors towards the enhancement of many of today's existing thermal applications performance. This is because these advanced working fluids exhibit exceptional thermophysical properties, and thus making them excellent candidates for replacing conventional working fluids. On the other hand, nanomaterials of carbon-base were proven throughout the literature to have the highest thermal conductivity among all other types of nanoscaled materials. Therefore, when these materials are homogeneously dispersed in a base fluid, the resulting suspension will theoretically attain orders of magnitude higher effective thermal conductivity than its counterpart. Despite this fact, there are still some challenges that are associated with these types of fluids. The main obstacle is the dispersion stability of the nanomaterials, which can lead the attractive properties of the nanofluid to degrade with time, up to the point where they lose their effectiveness. For such reason, this work has been devoted towards providing a systematic review on nanofluids of carbon-base, precisely; carbon nanotubes, graphene, and nanodiamonds, and their employment in thermal systems commonly used in the energy sectors. Firstly, this work reviews the synthesis approaches of the carbon-based feedstock. Then, it explains the different nanofluids fabrication methods. The dispersion stability is also discussed in terms of measuring techniques, enhancement methods, and its effect on the suspension thermophysical properties. The study summarizes the development in the correlations used to predict the thermophysical properties of the dispersion. Furthermore, it assesses the influence of these advanced working fluids on parabolic trough solar collectors, nuclear reactor systems, and air conditioning and refrigeration systems. Lastly, the current gap in scientific knowledge is provided to set up future research directions.

16.
Nanomaterials (Basel) ; 11(5)2021 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-33947011

RESUMEN

Magnesium hydride (MgH2) has received significant attention due to its potential applications as solid-state hydrogen storage media for useful fuel cell applications. Even though MgH2 possesses several attractive hydrogen storage properties, it cannot be utilized in fuel cell applications due to its high thermal stability and poor hydrogen uptake/release kinetics. High-energy ball milling, and mechanically-induced cold-rolling processes are the most common techniques to introduce severe plastic deformation and lattice imperfection in the Mg/MgH2. Furthermore, using one or more catalytic agents is considered a practical solution to improve both the de-/rehydrogenation process of MgH2.These treatments are usually dedicated to enhance its hydrogen storage properties and deduce its thermal stability. However, catalyzation of Mg/MgH2 powders with a desired catalytic agent using ball milling process has shown some disadvantages due to the uncontrolled distribution of the agent particles in the MgH2 powder matrix. The present study has been undertaken to employ a cold gas-dynamic spray process for catalyzing the fresh surfaces of mechanically-induced cold-rolled Mg ribbons with Ni powder particles. The starting Mg-rods were firstly heat treated and forged 200 times before cold rolling for 300 passes. The as-treated ribbons were then catalyzed by Ni particles, using cold gas-dynamic spray process. In this catalyzation approach, the Ni particles were carried by a stream of Ar gas via a high-velocity jet at a supersonic velocity. Accordingly, the pelted Ni particles penetrated the Mg-substrate ribbons, and hence created numerous micropores into the Mg, allowed the Ni particles to form a homogeneous network of catalytic active sites in Mg substrate. As the number of coating time increased to three times, the Ni concentration increased (5.28 wt.%), and this led to significant enhancement of the Mg-hydrogen storage capacity, as well as improving the de-/rehydrogenation kinetics. This is evidenced by the high value of hydrogen storage capacity (6.1 wt.% hydrogen) and the fast gas uptake kinetics (5.1 min) under moderate pressure (10 bar) and temperature (200 °C). The fabricated nanocomposite MgH2/5.28 wt.% Ni strips have shown good dehydrogenation behavior, indicated by their capability to desorb 6.1 wt.% of hydrogen gas within 11 min at 200 °C under 200 mbar of hydrogen pressure. Moreover, this system possessed long cycle-life-time, which extended to 350 h with a minimal degradation in the storage and kinetics behavior.

17.
Orphanet J Rare Dis ; 16(1): 128, 2021 03 12.
Artículo en Inglés | MEDLINE | ID: mdl-33712029

RESUMEN

PURPOSE: To present the detailed retinal phenotype of patients with Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy (LCA/EOSRD) caused by sequence variants in four genes, either not (n = 1) or very rarely (n = 3) previously associated with the disease. METHODS: Retrospective case series of LCA/EOSRD from four pedigrees. Chart review of clinical notes, multimodal retinal imaging, electrophysiology, and molecular genetic testing at a single tertiary referral center (Moorfields Eye Hospital, London, UK). RESULTS: The mean age of presentation was 3 months of age, with disease onset in the first year of life in all cases. Molecular genetic testing revealed the following disease-causing variants: PRPF8 (heterozygous c.5804G > A), PRPH2 (homozygous c.620_627delinsTA, novel variant), RP1 (homozygous c.4147_4151delGGATT, novel variant) and RPGR (heterozygous c.1894_1897delGACA). PRPF8, PRPH2, and RP1 variants have very rarely been reported, either as unique cases or case reports, with limited clinical data presented. RPGR variants have not previously been associated with LCA/EOSRD. Clinical history and detailed retinal imaging are presented. CONCLUSIONS: The reported cases extend the phenotypic spectrum of PRPF8-, PRPH2-, RP1-, and RPGR-associated disease, and the genotypic spectrum of LCA/EOSRD. The study highlights the importance of retinal and functional phenotyping, and the importance of specific genetic diagnosis to potential future therapy.


Asunto(s)
Proteínas del Ojo , Distrofias Retinianas , Proteínas del Ojo/genética , Humanos , Lactante , Proteínas Asociadas a Microtúbulos , Mutación/genética , Linaje , Fenotipo , Proteínas de Unión al ARN , Distrofias Retinianas/genética , Estudios Retrospectivos
18.
Am J Ophthalmol ; 221: 299-310, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-32795431

RESUMEN

PURPOSE: To determine the genetic background of sector retinitis pigmentosa (RP) natural history to better inform patient counseling. DESIGN: Retrospective case series. METHODS: Review of clinical notes, retinal imaging including color fundus photography (CFP), fundus autofluorescence (FAF), optical coherence tomography (OCT), electrophysiological assessment (ERG), and molecular genetic testing were performed in patients with sector RP from a single tertiary referral center. Main outcomes measured were demographic data, signs and symptoms, visual acuity, molecular genetics; and ERG, FAF, and OCT findings. RESULTS: Twenty-six molecularly confirmed patients from 23 different families were identified harboring likely disease-causing variants in 9 genes. The modes of inheritance were autosomal recessive (AR, n=6: USH1C, n=2; MYO7A, n=2; CDH3, n=1; EYS, n=1), X-linked (XL, n=4: PRPS1, n=1; RPGR, n=3), and autosomal dominant (AD, n=16: IMPDH1, n=3; RP1, n=3; RHO, n=10), with a mean age of disease onset of 38.5, 30.5, and 39.0 years old, respectively. Five of these genes have not previously been reported to cause sector RP (PRPS1, MYO7A, EYS, IMPDH1, and RP1). Inferior and nasal predilection was common across the different genotypes, and patients tended to maintain good central vision. Progression on serial FAF was observed in RPGR, MYO7A, CDH23, EYS, IMPDH1, RP1, and RHO-associated sector RP. CONCLUSIONS: The genotypic spectrum of the disease is broader than previously reported. The longitudinal data provided will help to make accurate patient prognoses and counseling as well as inform patients' potential participation in the increasing numbers of trials of novel therapeutics and access to future treatments.


Asunto(s)
Biología Molecular , Retinitis Pigmentosa/diagnóstico , Retinitis Pigmentosa/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Análisis Mutacional de ADN , Electrorretinografía , Proteínas del Ojo/genética , Femenino , Angiografía con Fluoresceína , Estudios de Asociación Genética , Humanos , Masculino , Persona de Mediana Edad , Linaje , Retina/fisiopatología , Retinitis Pigmentosa/fisiopatología , Estudios Retrospectivos , Tomografía de Coherencia Óptica , Agudeza Visual/fisiología , Pruebas del Campo Visual , Campos Visuales/fisiología , Adulto Joven
19.
Eye (Lond) ; 35(2): 409-417, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-32265509

RESUMEN

BACKGROUND: To evaluate the impact of injection frequency on yearly visual outcomes of patients treated with intravitreal aflibercept for neovascular age-related macular degeneration (nAMD) over a period of 5 years in a tertiary ophthalmic centre. DESIGN: Single centre, retrospective cohort study. PARTICIPANTS: Consecutive treatment-naive nAMD patients initiated on aflibercept injections 5 years ago. METHODS: The Moorfields OpenEyes database was searched for consecutive patients who were initiated on intravitreal aflibercept for nAMD in 2013-14 and the visual acuity (VA) in Early Diabetic Retinopathy Study (ETDRS) letters and injection records per year were recorded for a period of 5 years. Analyses of the whole cohort and a sub-sample of 5-year completers were done. The cohort was further grouped into Group A (on continuous treatment), Group B (early cessation of treatment) and Group C (interrupted treatment) to evaluate the relation between treatment frequency and visual outcomes. MAIN OUTCOME MEASURES: The primary end point was change in VA at 5 years; secondary outcomes included proportion of eyes that gained or maintained VA, number of injections received and the effect of treatment frequency. RESULTS: Data were collected on 468 patients (512 eyes). Sixty-six percent of the patients completed 5-year follow-up. The mean age of the whole cohort was 79.5 ± 8.5 years and the mean baseline VA was 58.3 ± 15.4 letters. Amongst the completers, final VA change was -2.9 (SD 23.4) ETDRS letters and the cumulative number of injections over 5 years was 24.2 (10.6). Group A had three letter gain and received significantly higher cumulative number of injections over 5 years than Group B and C (31.8, 14.6 and 18.4 respectively, p = 0.001). After adjusting for age and baseline VA, on average, final VA was +8.0 letters higher in the ≥20 injections group than the <20 group (p = 0.001). CONCLUSIONS: Aflibercept therapy results in sustained good visual outcome over 5 years in neovascular AMD eyes when early and persistent treatment is given.


Asunto(s)
Inhibidores de la Angiogénesis , Degeneración Macular Húmeda , Anciano , Anciano de 80 o más Años , Inhibidores de la Angiogénesis/uso terapéutico , Preescolar , Humanos , Inyecciones Intravítreas , Ranibizumab , Receptores de Factores de Crecimiento Endotelial Vascular , Proteínas Recombinantes de Fusión , Estudios Retrospectivos , Resultado del Tratamiento , Factor A de Crecimiento Endotelial Vascular , Agudeza Visual , Degeneración Macular Húmeda/tratamiento farmacológico
20.
Sci Rep ; 10(1): 20022, 2020 Nov 18.
Artículo en Inglés | MEDLINE | ID: mdl-33208799

RESUMEN

Hydrogen, which is a new clean energy option for future energy systems possesses pioneering characteristics making it a desirable carbon-free energy carrier. Hydrogen storage plays a crucial role in initiating a hydrogen economy. Due to its low density, the storage of hydrogen in the gaseous and liquids states had several technical and economic challenges. Despite these traditional approaches, magnesium hydride (MgH2), which has high gravimetric and volumetric hydrogen density, offers an excellent potential option for utilizing hydrogen in automobiles and other electrical systems. In contrast to its attractive properties, MgH2 should be mechanically and chemically treated to reduce its high activation energy and enhance its modest hydrogen sorption/desorption kinetics. The present study aims to investigate the influence of doping mechanically-treated Mg metal with 5 wt% amorphous Zr2Cu abrasive nanopowders in improving its kinetics and cyclability behaviors. For the first time, solid-waste Mg, Zr, and Cu metals were utilized for preparing MgH2 and amorphous Zr2Cu alloy (catalytic agent), using hydrogen gas-reactive ball milling, and arc melting techniques, respectively. This new nanocomposite system revealed high-capacity hydrogen storage (6.6 wt%) with superior kinetics and extraordinary long cycle-life-time (1100 h) at 250 °C.

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