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Nanotechnology and precision Engineering 2019年第1期2卷 1-7页

作者： Hisham M.Abourayana peter J.Dobbyn pat Whyte denis p.dowling Surface Engineering Group School of Mechanical and Materials Engineering University College Dublin Irish Micro Mouldings Inverin Co.

This study reports the development and performance of a pilot-scale barrel atmospheric plasma reactor for the atmospheric plasma activation treatment of polymer particles. The polymer particles treated included acrylonitrile butadiene styrene(ABS) and polypropylene(pp). These particles had diameters in the range of 3–5 mm. The initial studies were carried out using a laboratory-scale barrel reactor designed to treat polymer particle batch sizes of 20 g. A pilot-scale reactor that could treat 500 g particle batch sizes was then developed to facilitate pre-industrial-scale treatments. The effect of operating pulse density modulation(pDM) in the range 10%–100% and plasma treatment time on the level of activation of the treated polymers were then investigated. ABS revealed a larger decrease in water contact angle compared with pp after plasma treatment under the same conditions. The optimal treatment time of ABS(400 g of polymer particles) in the pilot-scale reactor was 15 min. The plasma-activated polymer particles were used to fabricate dog-bone polymer parts through injection *** testing of the resulting dog-bone polymer parts revealed a 10.5% increase in tensile strength compared with those fabricated using non-activated polymer particles.

关键词： Atmospheric pressure plasma Barrel plasma reactor polymer particles Water contact angle X-ray photoelectron spectroscopy Injection moulding

The penetration depth of atomic radicals in tubes with catalytic surface properties

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plasma Science and Technology 2024年第7期26卷 157-164页

作者： Domen pAUL Miran MOZETIC Rok ZApLOTNIK Alenka VESEL Gregor pRIMC denis DONLAGIC Jozef Stefan Institute Jamova Cesta 39Ljubljana 1000Slovenia Jozef Stefan International postgraduate School Jamova Cesta 39Ljubljana 1000Slovenia Faculty of Electrical Engineering and Computer Science University of MariborKoroska Cesta 46Maribor 2000Slovenia

Catalysis of molecular radicals is often performed in interesting experimental *** possible configuration is tubular *** radicals are introduced into the tubes on one side,and stable molecules are exhausted on the other *** penetration depth of radicals depends on numerous parameters,so it is not always feasible to calculate *** article presents systematic measurements of the penetration depth of oxygen atoms along tubes made from nickel,cobalt,and *** source of O atoms was a surfatron-type microwave *** initial density of O atoms depended on the gas flow and was 0.7×10^(21)m^(-3),2.4×10^(21)m^(-3),and 4.2×10^(21)m^(-3)at the flow rates of 50,300,and 600 sccm,and pressures of 10,35,and 60 pa,*** gas temperature remained at room temperature throughout the *** dissociation fraction decreased exponentially along the length of the tubes in all *** penetration depths for well-oxidized nickel were 1.2,1.7,and 2.4 cm,*** cobalt,they were slightly lower at 1.0,1.3,and 1.6 cm,respectively,while for copper,they were 1.1,1.3,and 1.7 cm,*** results were explained by gas dynamics and heterogeneous surface *** data are useful in any attempt to estimate the loss of molecular fragments along tubes,which serve as catalysts for the association of various radicals to stable molecules.

关键词： oxygen plasma penetration depth catalysis heterogeneous surface recombination atom loss

Laser-optimized pt-Y alloy nanoparticles embedded in pt-Y oxide matrix for high stability and ORR electrocatalytic activity

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Journal of Energy Chemistry 2024年第5期92卷 508-520页

作者： Riccardo Brandiele Andrea Guadagnini Mattia parnigotto Federico pini Vito Coviello denis Badocco paolo pastore Gian Andrea Rizzi Andrea Vittadini Daniel Forrer Vincenzo Amendola Christian Durante Department of Chemical Sciences University of PaduaVia Marzolo 135131 PadovaItaly Istituto di Chimica della Materia Condensata e di Tecnologie per l’Energia ICMATE-CNR via Marzolo 1 I-35131 PadovaItaly

The development of active yet stable catalysts for oxygen reduction reaction(ORR)is still a major issue for the extensive permeation of fuel cells into everyday *** nanostructured pt catalysts are to date the best available systems in terms of activity,the same is not true for stability,particularly under operating *** this work,pt_(Х)Y alloy nanoparticles are proposed as active and durable electrocatalysts for ***_(Х)Y nanoalloys are synthesized and further optimized by laser ablation in liquid followed by laser fragmentation in *** novel integrated laser-assisted methodology succeeded in producing pt_(Х)Y nanoparticles with the ideal size(pt catalysts,yet resulting remarkably more active with E_(1/2)=0.943 V ***,specific activity=1095μA cm^(-2) and mass activity>1000 A g^(-1).At the same time,the nanoalloys are embedded in a fine pt oxide matrix,which allows a greater stability of the catalyst than the commercial pt reference,as directly verified on a gas diffusion electrode.

关键词： Electrocatalysis GDE ORR pt_(2)Y pt_(3)Y LAL LFL Oxide support pto Nanoalloys

prevalence and Factors Associated with Refractive Errors among University Students at Mbarara University of Science and Technology, Uganda

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Open Journal of Ophthalmology 2024年第3期14卷 324-338页

作者： denis Kamara John Onyango Simon Arunga Mwanja pius pliers denis Tusingwire Mary Assumpta Ayoo Eric Ronald Mulongo Barnabas Atwiine Department of Ophthalmology Mbarara University of Science and Technology Mbarara City Uganda College of Health Sciences Makerere University Kampala Uganda London School of Hygiene and Tropical Medicine London England Faculty of Business and Development Studies Gulu University Gulu Uganda College of Health Sciences Lira University Lira Uganda

Introduction: WHO estimated that uncorrected refractive errors are the leading cause of visual impairment and second leading cause of blindness globally. University students are prone to developing refractive errors due to their curriculum that requires a lot of near work affecting their performance and quality of life unknowingly. Genetic and environmental factors are thought to play a role in the development of refractive errors. This study addresses the paucity of knowledge about refractive errors among university students in East Africa, providing a foundation for further research. Objectives: To determine the prevalence and factors associated with refractive errors among students in the Faculty of Medicine at Mbarara University of Science and Technology. Methodology: This was a cross-sectional descriptive and analytical study in which 368 undergraduate students selected using random sampling were assessed for refractive errors from March 2021-July 2021. Eligible participants were recruited and their VA assessment done after answering a questionnaire. Students whose VA improved on pin hole had subjective retinoscopy and results were compiled and imported to STATA 14 for analysis. Results: The prevalence of refractive errors was 26.36% with (95% CI) among university students especially myopia. Myopia is most predominant at 60%, followed by 37% Astigmatism and hyperopia of 3% among medical students. Astigmatism consisted of largely myopic astigmatism 72% (26) and 28% (10) compound/mixed astigmatism only. Student positive family history of refractive error was found to have a statistically significant relationship with refractive errors with AOR 1.68 (1.04 - 2.72) (95% CI) and p (0.032). Conclusion: The prevalence of refractive errors among university students, especially myopia, was found to be high and family history was associated with students having refractive errors.

关键词： Refractive Errors prevalence Myopia Astigmatism Hyperopia Hypermetropia University Students Blindness Visual Impairment

Microwave-Assisted Inactivation of Fomite-Microorganism Systems: Energy phase-Space projection

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American Journal of Analytical Chemistry 2022年第7期13卷 255-276页

作者： Victor J. Law denis p. dowling School of Mechanical and Materials Engineering University College Dublin Dublin Ireland

This paper describes the use of log-linear energy phase-space projections to analyze microwave-assisted inactivation of bacteria and viruses under different fomite conditions within multimode microwave ovens. The ovens are operated at a cavity-magnetron frequency of 2.45 ± 01 GHz. porous fomites (moist face towels, cotton swabs, kitchen sponges, and scrubbing pads, cigarette filters and N95-like respirators);along with non-porous hard surface syringe fomites are studied. The fomites are classed as dielectric;and absorb microwave energy to varying degrees depending on their complex dielectric permittivity. Microorganism resilience to microwave stress (defined as ≥4 log10 reduction in inactivation) when mapped using iso-volume trend-lines in energy phase-space reveals the persistence imparted by the fomite, and can be mapped between different microwave ovens. Microorganism resilience to thermal microwave-assisted treatment increases from vegetative Gram-negative to vegetative Gram-positive and on to Gram-positive spores. Bacteriophage MS2 and influenza viruses have an intermediate resilience dependency. It is shown that linear-scaled fomite temperature against process time graphs can differentiate between non-thermal and thermal micro-wave-assisted treatment of microorganisms.

关键词： Bacteria MS2 Hepatitis C Virus Human Immunodeficiency Virus Influenza Virus Disruption Inactivation Microwave Oven Data Analysis

Microwave-Assisted Au and Ag Nanoparticle Synthesis: An Energy phase-Space projection Analysis

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American Journal of Analytical Chemistry 2023年第4期14卷 149-174页

作者： Victor J. Law denis p. dowling School of Mechanical and Materials Engineering University College Dublin Dublin Ireland

Microwave-assisted synthesis of gold and silver nanoparticles, as a function of Green Chemistry, non Green Chemistry, and four applicator types are reported. The applicator types are Domestic microwave ovens, commercial temperature controlled microwave chemistry ovens (TCMC), digesters, and axial field helical antennae. For each of these microwave applicators the process energy budget where estimated (Watts multiplied by process time = kJ) and energy density (applied energy divided by suspension volume = kJ·mlp>-1p>) range between 180 ± 176.8 kJ, and 79.5 ± 79 kJ·mlp>-1p>, respectively. The axial field helical field an-tenna applicator is found to be the most energy efficient (0.253 kJ·mp>-1p> per kJ, at 36 W). Followed by microwave ovens (4.47 ± 3.9 kJ·mlp>-1p> per 76.83 ± 39 kJ), and TCMC ovens (2.86 ± 2.3 kJ·mp>-1p> per 343 ± 321.5 kJ). The digester applicators have the least energy efficiency (36.2 ± 50.7 kJ·mp>-1p> per 1010 ± 620 kJ). A comparison with reconstructed ‘non-thermal’ microwave oven inactivation microorganism experiments yields a power-law signature of n = 0.846 (Rp>2p> = 0.7923) four orders of magnitude. The paper provides a discussion on the Au and Ag nanoparticle chemistry and bio-chemistry synthesis aspects of the microwave applicator energy datasets and variation within each dataset. The visual and analytical approach within the energy phase-space projection enables a nanoparticle synthesis route to be systematically characterized, and where changes to the synthesis are to be mapped and compared directly with historical datasets. In order to help identify lower cost nanoparticle synthesis, in addition to potentially reduce synthesis energy to routes informed changes to potentially reduce synthesis energy budget, along with nanoparticle morphology and yield.

关键词： Turkevich Microwave-Assisted Synthesis Ag Au Hydroxyapatite Nanoparticle Functionalization Energy phase-Space projection

Microwave Detection, Disruption, and Inactivation of Microorganisms

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American Journal of Analytical Chemistry 2022年第4期13卷 135-161页

作者： Victor J. Law denis p. dowling School of Mechanical and Materials Engineering University College Dublin Dublin Ireland

This paper reviews three complex interactions between microwave energy and microorganisms (bacteria, fungi, and viruses). The first interaction comprises the detection of viruses within human blood using a 50-Ohm transmission-line vector net-analyzer (typically 0 to 10 dBm @ 2 to 8.5 GHz) where the blood is placed within a test chamber that acts as a non-50-Ohm discontinuity. The second interaction employs 1 to 6.5 W @ 8 to 26 GHz for microwave feed-horn illumination to inactivate microorganisms at an applied power density of 10 to 100 mWp>-2p>. The third interaction is within multi-mode microwave ovens, where microorganism cell membrane disruption occurs at a few 100 s of W @ 2.45 GHz and microorganism inactivation between 300 to 1800 W @ 2.45 GHz. Within the first microwave interaction, blood relaxation processes are examined. Whereas in the latter two microwave interactions, the following disruption, and inactivation mechanisms are examined: chemical cellular lysis and, microwave resonant absorption causing cell wall rupture, and thermodynamic analysis in terms of process energy budget and suspension energy density. In addition, oven-specific parameters are discussed.

关键词： Bacteria Fungi Virus Hepatitis C Virus Human Immunodeficiency Virus Detection Disruption Inactivation N95 Respirator Microwave Oven

Green Chemistry Allometry Test of Microwave-Assisted Synthesis of Transition Metal Nanostructures

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American Journal of Analytical Chemistry 2023年第11期14卷 493-518页

作者： Victor J. Law denis p. dowling School of Mechanical and Materials Engineering University College Dublin Dublin Ireland

Microwave irradiation is considered an important approach to Green Chemistry, because of its ability to rapidly increase the internal temperature of polar-organic compounds that lead to synthesis times of minutes rather than hours when compared to conventional thermal heating. This works describes a dual allometry test for the discrimination between the solvents and reagents used in the microwave-assisted synthesis of transition metal (zinc oxide, palladium silver, platinum, and gold) nanostructures. The test is performed in log-log process energy phase-space projection, where the synthesis data (kJ against kJ·molp>-1p>) has a power-law signature. The test is shown to discriminate between recommended Green Chemistry, problematic Green Chemistry, and Green Chemistry hazardous solvents. Typically, recommended Green chemistry exhibits a broad y-axes distribution within an upper exponent = 1 and lower exponent = 0.5. problematic Green Chemistry exhibits a y-axes narrower distribution with an upper exponent = 0.94 and lower exponent = 0.64. Non-Green Chemistry hazardous data exhibits a further narrowing of the y-axes distribution within upper exponent = 0.87 and lower exponent = 0.66. In all three cases, the y-axes is aligned to original database power-law signature. It is also shown that in the x-axes direction (process energy budget) the grouped order of magnitude decreases from four orders for recommended Green Chemistry solvent and reagent data, through two orders for non-Green Chemistry hazardous material and down to one order for problematic Green Chemistry.

关键词： Microwave-Assisted Synthesis Transition Metals Nanostructures Allometry Scaling power-Law Signature Green Chemistry

Microwave-Assisted Transition Metal Nanostructure Synthesis: power-Law Signature Verification

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American Journal of Analytical Chemistry 2023年第8期14卷 326-349页

作者： Victor J. Law denis p. dowling School of Mechanical and Materials Engineering University College Dublin Dublin Ireland

A power-law (y = cxn) signature between process energy budget (kJ) and process energy density (kJ·ml-1) of microwave-assisted synthesis of silver and gold nanostructures has been recently described [Law and denis. AJ... 详细信息

A power-law (y = cxp>np>) signature between process energy budget (kJ) and process energy density (kJ·mlp>-1p>) of microwave-assisted synthesis of silver and gold nanostructures has been recently described [Law and denis. AJAC, 14(4), 149-174, (2023)]. This study explores this relation further for palladium, platinum, and zinc oxide nanostructures. parametric cluster analysis and statistical analysis is used to test the power-law signature of over four orders of magnitude as a function of six microwave applicator-types metal precursor, non-Green Chemistry synthesis and claimed Green Chemistry. It is found that for the claimed Green Chemistry, process energy budget ranges from 0.291 to 900 kJ, with a residual error ranging between −33 to +25.9 kJ·mlp>-1p>. The non-Green Chemistry synthesis has a higher process energy budget range from 3.2 kJ to 3.3 MJ, with a residual error of −33.3 to +245.3 kJ·mlp>-1p>. It is also found that the energy profile over time produced by software controlled digestion applicators is poorly reported which leads to residual error problematic outliers that produce possible phase-transition in the power-law signature. The original Au and Ag database and new pd, pt and ZnO database (with and without problematic outliers) yield a global microwave-assisted synthesis power-law signature constants of c = 0.7172 ± 0.3214 kJ·mlp>-1p> at x-axes = 0.001 kJ, and the exponent, n = 0.791 ± 0.055. The information in this study is aimed to understand variations in historical microwave-assisted synthesis processes, and develop new scale-out synthesis through process intensification.

关键词： Microwave-Assisted Synthesis pd Ag pt Au ZnO power-Law Residual Error Statistical Analysis parametric Cluster Analysis

predictors of Fatal Outcome in Hospitalised Adult patients with Acute Kidney Injury at Two Tertiary Hospitals in Sub-Saharan Africa

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Open Journal of Nephrology 2024年第1期14卷 86-103页

作者： denis Georges Teuwafeu Fombo Enjeh Jabbossung Maimouna Mahamat Eric Aristide Nono Tomta Mbapah Leslie Tasha Francois Kaze Folefack Gloria Ashuntantang Faculty of Health Sciences University of Buea Buea Cameroon Triad Research Fundation Buea Cameroon Faculty of Medicine and Biomedical Sciences University of Yaounde I Yaounde Cameroon Department of nephrology Yaounde General Hospital Yaounde Cameroon Departement of Nephrology Yauonde Teaching Hospital Yaounde Cameroon

Introduction: Data on mortality in acute kidney injury (AKI) derives from high-income countries where AKI is hospital-acquired and occurs in elderly patients with a high burden of cardiovascular disease. In sub-Saharan Africa (SSA), AKI is community-acquired occurring in healthy young adults. We aimed to identify predictors of fatal outcomes in patients with AKI in two tertiary hospitals in Cameroon. Methods: Medical records of adults with confirmed AKI, from January 2018 to March 2020 were retrieved. The outcomes of interest were in-hospital deaths and presumed causes of death. We used multiple logistic regressions modeling to identify predictors of death. The study was approved by the ethics boards of both hospitals. Values were considered significant for a p-value of 0.05. Results: We included 285 patient records (37.2% females). The mean (SD) age was 50.1 (19.0) years. Hypertension (n = 97, 34.0%), organ failure (n = 88, 30.9%), and diabetes (n = 60, 21.1%) were the main comorbidities. The majority of patients had community-acquired AKI (78.6%, n = 224), were KDIGO stage 3 (88.8%, n = 253), and needed dialysis (52.6%, n = 150). Up to 16.7% (n = 25) did not receive what was needed. The in-hospital mortality rate was 29.1% (n = 83). Lack of access to dialysis (OR = 27.8;CI: 5.2 - 149.3, p = 0.001), hypotension (OR = 11.8;CI: 1.3 - 24.8;p = 0.001) and ICU admission (OR = 5.7;CI: 1.3 - 24.8, p = 0.001) were predictors of mortality. The presence of co-morbidities or underlying diseases (n = 46, 55%) were the main causes of death. Conclusions: In-hospital AKI mortality is high, as in other low- and middle-income economies. Lack of access to dialysis and the severity of the underlying illness are major predictors of death.

关键词： predictors Fatal Outcome Acute Kidney Injury Tertiary Hospital