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1.
J Med Life ; 17(1): 87-98, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38737655

RESUMO

This study aimed to identify novel Glyoxalase-I (Glo-I) inhibitors with potential anticancer properties, focusing on anthraquinone amide-based derivatives. We synthesized a series of these derivatives and conducted in silico docking studies to predict their binding interactions with Glo-I. In vitro assessments were performed to evaluate the anti-Glo-I activity of the synthesized compounds. A comprehensive structure-activity relationship (SAR) analysis identified key features responsible for specific binding affinities of anthraquinone amide-based derivatives to Glo-I. Additionally, a 100 ns molecular dynamics simulation assessed the stability of the most potent compound compared to a co-crystallized ligand. Compound MQ3 demonstrated a remarkable inhibitory effect against Glo-I, with an IC50 concentration of 1.45 µM. The inhibitory potency of MQ3 may be attributed to the catechol ring, amide functional group, and anthraquinone moiety, collectively contributing to a strong binding affinity with Glo-I. Anthraquinone amide-based derivatives exhibit substantial potential as Glo-I inhibitors with prospective anticancer activity. The exceptional inhibitory efficacy of compound MQ3 indicates its potential as an effective anticancer agent. These findings underscore the significance of anthraquinone amide-based derivatives as a novel class of compounds for cancer therapy, supporting further research and advancements in targeting the Glo-I enzyme to combat cancer.


Assuntos
Amidas , Antraquinonas , Inibidores Enzimáticos , Lactoilglutationa Liase , Humanos , Amidas/química , Amidas/farmacologia , Antraquinonas/farmacologia , Antraquinonas/química , Antineoplásicos/farmacologia , Antineoplásicos/química , Inibidores Enzimáticos/farmacologia , Inibidores Enzimáticos/química , Inibidores Enzimáticos/síntese química , Lactoilglutationa Liase/antagonistas & inibidores , Lactoilglutationa Liase/metabolismo , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Relação Estrutura-Atividade
2.
Ther Adv Infect Dis ; 11: 20499361241242218, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38550914

RESUMO

The resurgence of diphtheria in Nigeria, culminating in an outbreak surpassing previous records, has spotlighted the critical imperative for robust immunization policies amidst a milieu of vaccine hesitancy. This commentary delineates the multifaceted dimensions of the current diphtheria outbreak, which started in May 2022, juxtaposed against historical outbreaks, with a focal examination of the pervasive vaccine hesitancy and its underpinning sociocultural and systemic determinants. The discourse extends to a meticulous evaluation of Nigeria's public health response, underlined by the synergy with international organizations, reflecting a global collaborative ethos in combating the diphtheria menace. A critical appraisal of the prevailing immunization policies unveils a necessity for strategic amendments to invigorate vaccination uptake, essential for curbing the diphtheria outbreak and enhancing public health resilience. The reflections herein advocate for a comprehensive, culturally resonant, and sustainable public health paradigm, encompassing a synergistic approach of policy fortification, community engagement, and international collaboration to navigate the challenges posed by vaccine-preventable diseases epitomized by the ongoing diphtheria outbreak. Through a synthesis of historical lessons, contemporary challenges, and global solidarity, this piece contributes to the broader discourse on enhancing immunization coverage and infectious disease control in Nigeria.


Fighting diphtheria in Nigeria: the challenge of getting everyone vaccinated Recently, Nigeria has faced its worst diphtheria outbreak in years, showing how important it is to get people vaccinated. This article looks closely at the current outbreak, compares it to past ones, and explores why some people are hesitant to get vaccinated. We discuss the reasons behind this hesitation, including cultural and social factors. We also review how Nigeria is responding to the outbreak with help from international groups. We point out that Nigeria's vaccination policies need to be updated to encourage more people to get vaccinated, which is crucial to stop the outbreak and strengthen overall health defenses. The article calls for a well-rounded and lasting approach to public health that includes better policies, working closely with communities, and international cooperation.

3.
Antimicrob Resist Infect Control ; 13(1): 19, 2024 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-38355604

RESUMO

The escalating challenge of antimicrobial resistance (AMR) poses a considerable concern for global health, particularly impacting low- and middle-income countries (LMICs). This article highlights the critical importance of tackling AMR in LMICs by adopting the Global Antimicrobial Stewardship Accreditation Scheme (GAMSAS). GAMSAS is portrayed as a holistic and sustainable strategy for antimicrobial stewardship, extending beyond accreditation to include educational programs, capacity enhancement, improved surveillance, and support for AMS policy research. While acknowledging the global uptake of the scheme, the article highlights its preliminary phase of adoption in LMICs, particularly in high-AMR burden regions like Sub-Saharan Africa. The piece stresses the imperative for LMICs to integrate GAMSAS, underscoring its significance in optimizing antimicrobial usage and patient health outcomes. It advocates for an all-encompassing approach that leverages international cooperation and sustained financial backing, crucial for the effective deployment and enduring success of antimicrobial stewardship efforts in these key areas.


Assuntos
Anti-Infecciosos , Gestão de Antimicrobianos , Humanos , Países em Desenvolvimento , Anti-Infecciosos/uso terapêutico , Cooperação Internacional , Saúde Global
4.
Ocul Immunol Inflamm ; : 1-7, 2023 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-37134304

RESUMO

PURPOSE: To assess the efficacy of treatment on acute posterior multifocal placoid pigment epitheliopathy (APMPPE) and relentless placoid chorioretinopathy (RPC). METHODS: Cases were identified from three UK uveitis centers. Retrospective analysis of visual acuity recovery; OCT structural outcomes; and retinal lesion quantification in observed and treated cases of APMPPE/RPC. RESULTS: There were nine APMPPE and three RPC cases. Out of 12 patients, six were female. Median age: 26.5 years (range, 20-57 years). Four cases (six eyes) were observed, and eight cases (15 eyes) received corticosteroids ± immunosuppression. 4/4 observed and 6/10 treated foveal involving eyes regained 0.00 LogMAR vision. Observed lesions achieved more favorable anatomical outcomes. New lesions post-presentation developed in 1/6 (16%) observed eye versus 10/15 (66%) treated eyes. In three cases, a delayed, rebound lesion occurrence was observed post-high-dose corticosteroids. CONCLUSIONS: While subject to potential treatment bias, in this small case series, natural history alone appears non-inferior to corticosteroid treatment.

5.
Eye (Lond) ; 37(11): 2310-2315, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-36513858

RESUMO

BACKGROUND/AIM: To report 5-year real-world efficacy and safety data following the treatment of chronic diabetic macular oedema (DMO) with the intravitreal 0.19 mg fluocinolone acetonide implant(ILUVIEN). METHODS: Retrospective cohort study of 31 eyes treated with ILUVIEN for chronic DMO at a tertiary centre in Birmingham (UK). Best corrected visual acuity (BCVA) and central retinal thickness (CRT) were recorded at baseline, and then at 1-,2-,3-, and 5-years. Safety was assessed based on intraocular pressure (IOP) -lowering medication, surgery, and other complications. RESULTS: BCVA significantly improved 1-year post-ILUVIEN (+4.2 letters, p < 0.05) and gradually reverted to baseline levels over the 5-year period of follow-up (+0.2 letters at year-5). A significant and sustained CRT reduction was observed throughout the 5-years. The proportion of eyes on IOP-lowering medication increased from 16% at baseline, to 70% at 5-years (p < 0.001) with eyes on a mean of 1.3 medications. Laser trabeculoplasty (n = 2), cyclodiode laser (n = 1), and trabeculoplasty and trabeculotomy (n = 1, in the same eye; 3.2%) were required for uncontrolled IOP. Other complications included endophthalmitis (n = 1) and vitreous haemorrhage (n = 1). 58% of eyes required additional intravitreal injections, with a mean 29.2 months to first injection. We observed a 69% reduction in treatment burden following treatment with ILUVIEN implant. CONCLUSIONS: Our real-world results confirm the efficacy of the ILUVIEN implant over 5 years, with two-thirds of eyes having improved or stable visual acuity 5 years after ILUVIEN, and an overall sustained improvement in anatomical outcome. Although the rate of IOP-lowering medications use was higher than previously reported, the rate of incisional IOP-lowering surgery and other complications remained low and in keeping with rates reported in larger studies.


Assuntos
Diabetes Mellitus , Retinopatia Diabética , Edema Macular , Humanos , Fluocinolona Acetonida , Glucocorticoides/uso terapêutico , Edema Macular/tratamento farmacológico , Edema Macular/etiologia , Retinopatia Diabética/complicações , Retinopatia Diabética/tratamento farmacológico , Estudos Retrospectivos , Resultado do Tratamento , Injeções Intravítreas , Implantes de Medicamento/uso terapêutico
6.
Bull Natl Res Cent ; 46(1): 281, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36532680

RESUMO

Background: In Nigeria, effective case management and evaluation of pulmonary tuberculosis treatment outcomes are an integral part of controlling the spread of infectious diseases. The study reviewed the treatment outcomes of pulmonary tuberculosis and the factors associated with rates of successful and unsuccessful treatment outcomes in the 21 referral hospitals in Kebbi State, Nigeria. Methods: Documented records of pulmonary tuberculosis patients from January 2018 to December 2021 in 21 Local Area Councils in Kebbi State, Northern Nigeria were reviewed. A structured questionnaire collated the socio-demographic and clinical data from the documented records. Descriptive statistics were used to compute and analyse the outcomes of successful and unsuccessful treatment. Logistic regression models were used to determine the association of socio-demographic and clinical data with the unsuccessful treatment outcomes. Results: The study reviewed data from 6114 records of TB patients. 1161 (18.9%) started treatment, 963 (82.9%) were males and 198 (17.1%) were females. Of the 1161 patients, 985 (18.2%) had documented treatment outcomes. 932 of 985 (95.1%) had a pulmonary infection. 64 (5.8%) patients with documented treatment outcomes were HIV seropositive. 903 (91.7%) were successfully treated, and 82 (8.3%) failed. Of the patients with failed treatment outcomes, 15 (1.5%) were lost to follow-up, 43 (4.4%) defaulted and 24 (2.4%) died. In the logistic analysis, the odds of unsuccessful treatment outcomes were higher among elderly patients (AOR = 2.00, 95% CI 1.37-2.92), patients with extrapulmonary infections (AOR = 2.40, 95% CI 1.12-5.39), and with old cases of pulmonary TB (AOR = 3.03, 95% CI 1.47-7.19) when compared to their groups. Conclusions: The study reported a treatment success rate of 91.7% among TB patients attending public hospitals in Kebbi State. The outcome was higher than the projected success rate of 85% set by the WHO. However, one-fourth of the total patients reviewed were not documented for treatment. Therefore, the need to design an appropriate recruitment strategy to identify and enrol those patients for an effective and successful TB control program in Nigeria.

7.
Materials (Basel) ; 15(7)2022 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-35407853

RESUMO

Graphene oxide-modified rubberized engineered cementitious composite (GO-RECC) is attracting the attention of researchers because of the reported benefits of the GO and crumb rubber (CR) on the strength and deformation properties of the composite. While it is well established that GO negatively affects the workability of cementitious composites, its influence on the attainment of the desired self-compacting (SC) properties of ECC has not yet been thoroughly investigated, especially when combined with crumb rubber (CR). In addition, to simplify the number of trial mixes involved in designing SC-GO-RECC, there is a need to develop and optimize the process using Design of Experiment (DOE) methods. Hence, this research aims to investigate and model using response surface methodology (RSM), the combined effects of the GO and CR on the SC properties of ECC through the determination of T500, slump flow, V-funnel, and L-box ratio of the SC-GORECC as the responses, following the European Federation of National Associations Representing for Concrete (EFNARC) 2005 specifications. The input factors considered were the GO by wt.% of cement (0.02, 0.04, 0.06, and 0.08) and CR as a replacement of fine aggregate by volume (5, 10, and 15%). The results showed that increasing the percentages of GO and CR affected the fresh properties of the SC-GORECC adversely. However, all mixes have T500 of 2.4 to 5.2 s, slump flow of 645 to 800 mm, V-funnel time of 7.1 to 12.3 s, and L-box ratio (H2/H1) of 0.8 to 0.98, which are all within acceptable limits specified by EFNARC 2005. The developed response prediction models were well fitted with R2 values ranging from 91 to 99%. Through the optimization process, optimal values of GO and CR were found to be 0.067% and 6.8%, respectively, at a desirability value of 1.0.

8.
Materials (Basel) ; 15(7)2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35407920

RESUMO

One of the primary causes of the low mechanical properties of rubberized concrete is the weak bond between crumb rubber (CR) and hardened cement paste. Many CR pretreatment techniques have been researched in an attempt to mitigate this problem. The NaOH pretreatment method is one of the most widely used, although the reported results are inconsistent due to the absence of standardized NaOH pretreatment concentrations and CR replacement levels. This study aims to develop models for predicting the mechanical and shrinkage properties of NaOH-pretreated CR concrete (NaOH-CRC) and conduct multi-objective optimization using response surface methodology (RSM). The RSM generated experimental runs using three levels (0, 5, and 10%) of both NaOH pretreatment concentration and the CR replacement level of fine aggregate by volume as the input factors. At 28 days, the concrete's compressive, flexural, and tensile strengths (CS, FS, and TS), as well as its drying shrinkage (S), were evaluated as the responses. The results revealed that higher CR replacements led to lower mechanical strengths and higher shrinkage. However, the strength loss and the shrinkage significantly reduced by 22%, 44%, 43%, and 60% for CS, FS, TS, and S, respectively, after the pretreatment. Using field-emission scanning electron microscopy (FESEM), the microstructural investigation indicated a significantly reduced interfacial transition zone (ITZ) with increasing NaOH pretreatment. The developed RSM models were evaluated using ANOVA and found to have high R2 values ranging from 78.7% to 98%. The optimization produced NaOH and CR levels of 10% and 2%, respectively, with high desirability of 71.4%.

9.
Materials (Basel) ; 15(4)2022 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-35208049

RESUMO

Producing high-strength self-compacting concrete (SCC) requires a low water-cement ratio (W/C). Hence, using a superplasticizer is necessary to attain the desired self-compacting properties at a fresh state. The use of low W/C results in very brittle concrete with a low deformation capacity. This research aims to investigate the influence of crumb rubber (CR), fly ash (FA), and nanosilica (NS) on SCC's workability and mechanical properties. Using response surface methodology (RSM), 20 mixes were developed containing different levels and proportions of FA (10-40% replacement of cement), CR (5-15% replacement of fine aggregate), and NS (0-4% addition) as the input variables. The workability was assessed through the slump flow, T500, L-box, and V-funnel tests following the guidelines of EFNARC 2005. The compressive, flexural, and tensile strengths were determined at 28 days and considered as the responses for the response surface methodology (RSM) analyses. The results revealed that the workability properties were increased with an increase in FA but decreased with CR replacement and the addition of NS. The pore-refining effect and pozzolanic reactivity of the FA and NS increased the strengths of the composite. Conversely, the strength is negatively affected by an increase in CR, however ductility and deformation capacity were significantly enhanced. Response surface models of the mechanical strengths were developed and validated using ANOVA and have high R2 values of 86-99%. The optimization result produced 36.38%, 4.08%, and 1.0% for the optimum FA, CR, and NS replacement levels at a desirability value of 60%.

10.
Ocul Immunol Inflamm ; 30(3): 560-569, 2022 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-34242103

RESUMO

PURPOSE: This review aims to present the state of the art to understand the pathophysiology of ocular toxoplasmosis (OT), providing further foundations that would help to improve the future treatment and prognosis of this potentially blinding disease. METHODS: A thorough literature search was performed in PubMed database. An additional search was made in Google Scholar to complete the collected items. RESULTS: Toxoplasma gondii ocular infection is one of the most frequent causes of posterior uveitis. Despite the ocular barriers, the parasite reaches the eye through different mechanisms. Once inside, it remains encysted livelong within the retina, and recurrences cannot be completely avoided. The complexity of host-parasite interactions, leading to the success of this parasite, encompasses host factors such as genetic predisposition, immune status, and age; and parasite factors such as strain diversity, virulence, phylogenetic origin, and geographical distribution. These factors influence the clinical presentation, course, and progression of the disease. Additional elements, such as pregnancy, eating behavior, and environmental, social, and cultural factors may also contribute to this complex balance. CONCLUSIONS: The host-parasite interaction in OT is a complex and multifactorial relationship, with the parasite always on the driving edge of the game. There are still multiple incompletely understood fields to be investigated. Future research would permit further insight into the immune-biology of the parasite and recognition of the host-parasite interplay to improve the diagnostic and management performance.


Assuntos
Toxoplasma , Toxoplasmose Ocular , Interações Hospedeiro-Parasita , Humanos , Filogenia , Retina , Toxoplasmose Ocular/tratamento farmacológico
11.
Int Ophthalmol ; 42(1): 295-321, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34370174

RESUMO

PURPOSE: This review aims to summarize the current knowledge concerning the clinical features, diagnostic work-up and therapeutic approach of ocular toxoplasmosis focusing mainly on the postnatally acquired form of the disease. METHODS: A meticulous literature search was performed in the PubMed database. A supplementary search was made in Google Scholar to complete the collected items. RESULTS: Ocular toxoplasmosis is one of the most frequent infectious etiologies of posterior uveitis. It typically presents with retinochoroiditis. Setting an accurate diagnosis depends to a considerable degree on detecting characteristic clinical characteristics. In addition to the evaluation of clinical features, the diagnosis of toxoplasmosis relies at a large degree on serologic testing. The detection of the parasite DNA in the aqueous or vitreous humor can provide evidence for a definitive diagnosis. The current mainstay for the treatment, if necessary, is the use of oral antibiotic with systemic corticosteroids. Recent evidence suggests other therapeutic approaches, such as intravitreal antibiotics can be used. CONCLUSION: Recent developments in the diagnostic and therapeutic approach have contributed to preventing or limiting vision loss of patients suffering from ocular toxoplasmosis. Further studies are required to provide a better understanding of epidemiology, pathogenesis, diagnosis, and treatment with a significant impact on the management of this challenging clinical entity.


Assuntos
Coriorretinite , Toxoplasma , Toxoplasmose Ocular , Uveíte Posterior , Coriorretinite/diagnóstico , Coriorretinite/tratamento farmacológico , Olho , Humanos , Toxoplasmose Ocular/diagnóstico , Toxoplasmose Ocular/tratamento farmacológico , Toxoplasmose Ocular/epidemiologia
12.
Polymers (Basel) ; 13(23)2021 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-34883646

RESUMO

Petroleum sludge is a waste product resulting from petroleum industries and it is a major source of environmental pollution. Therefore, developing strategies aimed at reducing its environmental impact and enhance cleaner production are crucial for environmental mortar. Response surface methodology (RSM) was used in designing the experimental work. The variables considered were the amount of petroleum sludge ash (PSA) in weight percent and the ratio of sodium silicate to sodium hydroxide, while the concentration of sodium hydroxide was kept constant in the production of geopolymer mortar cured at a temperature of 60 °C for 20 h. The effects of PSA on density, compressive strength, flexural strength, water absorption, drying shrinkage, morphology, and pore size distribution were investigated. The addition of PSA in the mortar enhanced the mechanical properties significantly at an early age and 28 days of curing. Thus, PSA could be used as a precursor material in the production of geopolymer mortar for green construction sustainability. This study aimed to investigate the influence of PSA in geopolymer mortar.

13.
Materials (Basel) ; 14(21)2021 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-34771834

RESUMO

In the industries of petroleum extraction, a large volume of oily sludge is being generated. This waste is usually considered difficult to dispose of, causing environmental and economic issues. This study presented the novel experimental method of manufacturing mortar used in civil construction by cement and oily sludge ash (OSA). The defined method was described with a logical experimental study conducted to examine a feasible manufacturing method for casting cement-based mortars by partially replacing cement with OSA. Replacement concentrations for OSA ranged from 0 to 20 percent by cement weight, while the water-to-cement (w/c) ratio was varied from 0.4 to 0.8, and the amount of sand was kept constant. The strengths and absorption rate of the mortar were monitored for 28 days. The OSA contains a crystalline structure with packs of angular grains. Because of OSA in the cement-based mortar mixtures and water-to-cement ratios, the mechanical strength was improved significantly. However, the water absorption trend increased linearly. Using variance analysis, the influence of OSA and w/c ratio on the behavior of mortar was acquired. The developed models were significant for all p-value reactions of <5%. Numerical optimization results showed that the best mixture can be obtained by replacing 8.19 percent cement with OSA and 0.52 as a ratio of w/c.

14.
Materials (Basel) ; 14(19)2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34639894

RESUMO

Crumb rubber (CR) from scrap tires is used as a partial replacement of fine aggregates in cement paste. This promotes the sustainable development of the environment, economy, and society, as waste tires are non-biodegradable and flammable. They occupy large landfill areas and are breeding grounds for mosquitoes and rodents. Inclusion of CR in mortar leads to several improvements on the mixture properties such as ductility, toughness, and impact resistance. However, it exhibits lower strengths and Modulus of Elasticity (ME). Therefore, to promote the use of mortar containing CR, it is vital to improve its mechanical strength. Past studies proved that nano-silica (NS) improves the strength of concrete due to the physico-chemical effects of NS. This study aims to examine the mechanical properties of crumb rubber mortar containing nano-silica (NS-CRM) and to develop models to predict these properties using Response Surface Methodology (RSM). Two variables were considered, CR as partial replacement to sand by volume (0%, 7.5%, 15%), and NS as partial replacement to cement by weight (0%, 2.5%, 5%). The results demonstrated a significant improvement in the mechanical properties of CRM when incorporating NS, and the models developed using RSM were acceptable with a 2% to 3% variation.

15.
Materials (Basel) ; 14(15)2021 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-34361355

RESUMO

This research aims to study the effect of the dosage of anhydrous sodium metasilicate activator on the long-term properties of fly ash-based one-part alkali-activated binders (OPAAB) cured at ambient conditions. Powdered sodium metasilicate activator was utilized in the range of 8-16% by weight of the fly ash in producing the OPAAB. The properties examined are hardened density, compressive strength, flexural strength, water absorption, efflorescence formation, and microstructural analysis. The experimental result revealed that the binders exhibited excellent long-term strength properties. The compressive strength of the OPAAP is well correlated with its hardened density. The pastes were found to exhibit good soundness characteristics over the long-term. The absorption of water decreases with an increase in the activator dosage from 8-12%, and beyond that, the water absorption relatively remains the same. Field emission scanning electron microscope (FESEM) micrograph revealed uniformly formed solid matrices with the micro-crack present were observed in the samples. The larger pore size promotes the crystallization of the resulting hydrate substances (N, C)-A-S-H gel. The initial dissolution of the OPAAP occurred within the first 30 min. At longer age of curing, mixtures with a higher dosage of powdered activator tend to absorb less water. Strength properties beyond 28 days are considered as the long-term strength.

16.
Materials (Basel) ; 14(13)2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34279334

RESUMO

Emerging as a new technology, carbon fiber-reinforced polymer (CFRP) has been introduced to rehabilitate and strengthen steel structures using an adhesive agent. However, the outdoor service temperature is potentially degrading to the mechanical strength of the adhesive, as well as affecting the bonding of the strengthened steel structure. Therefore, this paper aims to investigate the bond relationship of CFRP-strengthened steel plates exposed to service temperatures. Two types of experiments were conducted to determine the tensile and flexural performance of CFRP-strengthened steel plates. The experiments were designed using a Box-Behnken design (BBD) and response surface methodology (RSM) by considering three parameters: service temperature (25 °C, 45 °C and 70 °C), number of CFRP layers (one, three and five layers) and bond length (40, 80 and 120 mm). The findings show the dominant failure mode transformed from adhesion failure between steel and adhesive interfaces to adhesion failure between CFRP and adhesive interfaces as the service temperature increased. The tensile strength improved by 25.62% when the service temperature increased. Field emission scanning electron microscope (FESEM) analysis proved that the strength enhancement is due to the densification and reduction of the adhesive particle microstructure gaps through the softening effect at service temperature. However, service temperature is found to have less impact on flexural strength. Incorporating the experimental results in RSM, two quadratic equations were developed to estimate the tensile and flexural strength of CFRP-strengthened steel plates. The high coefficient of determination, R2, yields at 0.9936 and 0.9846 indicate the high reliability of the models. Hence, it can be used as an estimation tool in the design stage.

17.
Materials (Basel) ; 14(13)2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34279338

RESUMO

To avoid explosive spalling during elevated temperature, crumb rubber (CR) is being added to the manufacturing of engineered cementitious composites (ECC). However, the addition of CR particles adversely affects the mechanical properties of ECC. Therefore, to overcome this issue, nano-silica (NS) is added into rubberized ECC mixture as cementitious material additives. Response surface methodology (RSM) has been utilized to optimize the mixtures of the rubberized ECC with variables: CR (0, 2.5, and 5 vol.%), polyvinyl alcohol (PVA) fiber (0, 1, and 2 vol.%), NS (0, 1, and 2 vol.%), and fly ash (0, 25, and 50 vol.%). The experimentally measured responses are flexural strength, direct tensile strength, elastic modulus, Poisson's ratio, creep, and drying shrinkage. Mathematical models to predict the targeted responses have been developed using RSM. As a result, a high correlation between the factors and responses has been exhibited by the developed models and the accuracy of fit, where less than 9.38% of the variation was found between the predicted and validated results. The experimental results revealed that the rubberized ECC with the incorporation of nano-silica exhibited a higher compressive strength, direct tensile strength, flexural strength, elastic modulus, Poisson's ratio, and lower drying shrinkage.

18.
Materials (Basel) ; 14(12)2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34208431

RESUMO

Waste tire and fly ash (FA) are two waste materials whose disposal and rapid rate of accumulation are among the pressing sources of concern and threat to the environment. Although much research exists on the use of these materials in cementitious composites, very little literature is available on the effectiveness of combining them in high volumes for concrete production. This work aimed to utilize crumb rubber (CR) from waste tires as a partial replacement of fine aggregate at 15%, 22.25%, and 30% by volume, and high-volume fly ash (HVFA) replacement of cement at 50%, 60%, and 70% (by weight of cementitious materials) to produce high-volume fly ash-crumb rubber concrete (HVFA-CRC). Using the central composite design (CCD) option of the response surface methodology (RSM), 13 mixes were produced with different combinations and levels of the CR and FA (the input factors) on which the responses of interest (compressive, flexural, and tensile strengths) were experimentally investigated. Furthermore, the composite influence of CR and HVFA on the workability of the concrete was assessed using the slump test. The results showed a decline in the mechanical properties with increasing replacement levels of the CR and HVFA. However, up to 22.25% and 60% of CR and HVFA replacements, respectively, produced a structural HVFA-CRC with a compressive strength of more than 20 MPa at 28 days. Response predictive models were developed and validated using ANOVA at a 95% confidence level. The models had high R2 values ranging from 95.26 to 97.74%. Multi-objective optimization was performed and validated with less than 5% error between the predicted and experimental responses.

19.
Clin Ophthalmol ; 15: 1703-1713, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33935487

RESUMO

PURPOSE: To compare and report the 2-year treatment outcomes from 3 different anti-VEGF treatment regimens in treating neovascular aged-related macular degeneration (nAMD): Ranibizumab pro re nata (Ranibizumab-PRN); Ranibizumab treat and extend (Ranibizumab-T&E); Aflibercept fixed first year dosing (7 injections) with treat and extend in subsequent year (Aflibercept-Fixed). METHODS: All treatment-naïve nAMD patients who completed 24 months of monitoring from a single treatment center were included. Patients received the initial loading dose of three injections (4-weekly interval), followed by one of the 3 treatment regimens. Primary outcomes were changes in visual acuity (VA) and central retinal thickness (CRT). Secondary outcome was number of injections required in each year. Data analysis included last observation carried forward (LOCF) for patients with incomplete year-2 follow-up. RESULTS: A total of 249 eyes (230 patients) were studied: 121 Ranibizumab-PRN; 65 Ranibizumab-T&E, and 63 Aflibercept-Fixed. Baseline median VA (ETDRS letters) for Ranibizumab-PRN, Ranibizumab-T&E, and Aflibercept-Fixed was 53.9, 61.1, and 54.9 letters, achieving final VA of 54.9, 65.1, and 65.1 letters, respectively. Hence, the number of letters increased at the end of 24 months for each group was +1.0 (Ranibizumab-PRN), +4.0 (Ranibizumab-T&E), highest +10.2 in Aflibercept-Fixed group. Median number of injections over 2 years (year-1/year-2) was 5/1 for Ranibizumab-PRN, 9/6 for Ranibizumab-T&E, and 7/5 for Aflibercept-Fixed. Both Ranibizumab-T&E and Aflibercept-Fixed also shared the same reduction of median CRT (115 µm), higher than Ranibizumab-PRN (83 µm). CONCLUSION: We report VA improvement from all three different treatment regimens with both Aflibercept-Fixed and Ranibizumab-T&E regimens achieving the same higher final VA. Aflibercept-Fixed dosing may have more favorable efficacy with the highest VA gain and comparatively lower dosing frequency whereas Ranibizumab-T&E may be more efficient than Ranibizumab-PRN regimen, according to our study.

20.
Afr J Infect Dis ; 15(1): 47-52, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33884358

RESUMO

BACKGROUND: The present study determined the incidence of rifampicin resistance M. tuberculosis among outpatients at the General Hospital Yauri, Kebbi State, Nigeria. MATERIALS AND METHODS: The study is a cross-sectional study conducted from February 2018 to October 2019. Sociodemographic data were collected from hospital registration books. Rifampicin resistance M. tuberculosis was detected using GeneXpert Model GX-IV following manufacturers' instruction. Descriptive statistics and logistic regression were computed using SPSS version 20. The results were presented as odds ratios with associated 95% confidence intervals, and P-value at 0.05. RESULT: Of the 837 samples, 65.8% (551/837) were males, and 34.2% (286/837) females, 11.4% (95/837) HIV-seropositive. M. tuberculosis was detected in 15.5% (130/837), of which 116/130 (89.23%) were males and 14/130 (10.77%) females. M. tuberculosis-HIV coinfection was detected in 9.47% (9/95) of HIV positive. Rifampicin resistance was observed in 1.3% (11/837), 7.7% (10/130) in M. tuberculosis patients and 1.05% (1/94) in HIV seropositive. In logistic regression, the odds ratio for having a rifampicin-resistant M. tuberculosis was 0.49 (0.15-1.54) for > 30 years; taking <30 years as the reference value, 1.02 (1.00-1.03) for male; taking female as the reference value, and 0.78 (0.09-6.15) for HIV positive, taking negative as the reference value. CONCLUSION: This study reported the current incidence rate of rifampicin-resistant M. tuberculosis at the General Hospital Yelwa Yauri, Kebbi State, Nigeria, among presumptive TB patients. Patients diagnosed with rifampicin-resistant M. tuberculosis were predominantly male adults. Thus, frequent screening is vital for surveillance and reduces the risk of transmission and spread of M. tuberculosis infections.

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