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1.
Environ Monit Assess ; 196(4): 352, 2024 Mar 11.
Article in English | MEDLINE | ID: mdl-38466376

ABSTRACT

With characterized for complex and maximum substance (suspended solids, broke up oil, a mixture of inorganic and chromium sulfides), tannery wastewater was subjected to a treatment process on removal of chemical oxygen demand (COD) via upstream anaerobic sludge blanket reactor where we found reduced departure efficiencies and that process limits were affected by the assortments in regular stacking rates, closeness of chromium, and sulfides. Hence, a combination of the aerobic-anaerobic hybrid reactor was set up for sequential treatment to determine possible COD reduction. This study investigated the biological degradation of tannery wastewater in a laboratory-scale sequential up-flow aerobic-anaerobic reactor. The aerobic zone at the top was packed with spherical ball-shaped polyhedral polypropylene, and the anaerobic zone at the bottom was packed medium with granular media. The aeration flow rate varied by 2 L/min, 4 L/min, and 6 L/min in the aerobic zone, and the reactor maintained an organic loading rate (OLR) of 5 kg COD/m3/d. Parameters like COD and gas yield assess the performance of the reactor. The maximum COD of 86% is removed in the anaerobic zone with an aeration rate of 6 L/min, and the 1800-mL methane gas yield is measured by the 29th day.


Subject(s)
Bioreactors , Wastewater , Anaerobiosis , Biological Oxygen Demand Analysis , Environmental Monitoring , Chromium , Sulfides , Waste Disposal, Fluid , Oxygen
2.
Eur Arch Otorhinolaryngol ; 280(3): 985-1004, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36350369

ABSTRACT

PURPOSE: Hyperacusis is the hypersensitivity to auditory stimuli that would typically not affect those with hearing sensitivity within normal limits. The prevalence of hyperacusis in the general population has been estimated to range from 9% to 15%. There is no universally accepted definition for what defines hyperacusis among kindred illnesses of poor sound tolerance. As a result, hyperacusis prevalence varies more, which has an impact on both assessment and treatment. This study aims to determine the efficacy of the different clinical assessment measures of hyperacusis in assessing hyperacusis through a systematic review. METHODS: A review and reference of literature were done on hyperacusis, and assessment measures were used. A review of 23 articles was conducted to highlight these measures used. Most selected studies included retrospective, prospective, survey, and experimental designs. Study quality reported an overall low risk of bias. RESULTS: This review reports the summary and the current evidence of clinical assessment measures used for diagnosing hyperacusis. CONCLUSIONS: This review highlights a protocol that may be used in the clinical diagnosis of hyperacusis. It also shows the necessity to standardize and validate assessment measures for the younger population.


Subject(s)
Hearing , Hyperacusis , Humans , Hyperacusis/diagnosis , Hyperacusis/epidemiology , Retrospective Studies , Prospective Studies , Hearing Tests
3.
Chem Soc Rev ; 50(12): 6700-6719, 2021 Jun 21.
Article in English | MEDLINE | ID: mdl-33959737

ABSTRACT

Metallenes, atomically thin layers composed primarily of under-coordinated metal atoms, have emerged as the newest members in the family of 2D nanomaterials. Furthermore, the remarkable physicochemical properties associated with metallenes coupled with the ease of applying chemical modifications result in exciting opportunities towards catalyst engineering for electrochemical conversions. Especially in recent years, interest around metallenes has grown, evidenced by the surge in available literature. As such, it is imperative to review the findings and present directions for the future. In this review, we highlight the techniques available for deriving metallenes and further discuss the modification strategies commonly employed in devising metallenes to better suit applications in electrocatalysis. We provide a rational understanding of how each strategy drives performance enhancements and present gaps in the knowledge, necessary for further advancements in the field.

4.
Clin Infect Dis ; 72(12): 2212-2214, 2021 06 15.
Article in English | MEDLINE | ID: mdl-32968772

ABSTRACT

Following increases in reported cases of hepatitis A, we assessed the impact of hepatitis A vaccine in Alaska Native persons. During 1996-2018, only 6 cases of hepatitis A were identified, all in unvaccinated adults. Populations can be protected against hepatitis A by achieving sufficient vaccination coverage over time.


Subject(s)
Hepatitis A virus , Hepatitis A , Adult , Alaska/epidemiology , Hepatitis A/epidemiology , Hepatitis A/prevention & control , Humans , Vaccination , Vaccination Coverage
5.
Clin Infect Dis ; 73(Suppl 1): S77-S80, 2021 07 15.
Article in English | MEDLINE | ID: mdl-33956136

ABSTRACT

A suspected outbreak of influenza A and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at a long-term care facility in Los Angeles County was, months later, determined to not involve influenza. To prevent inadvertent transmission of infections, facilities should use highly specific influenza diagnostics and follow Centers for Disease Control and Prevention (CDC) guidelines that specifically address infection control challenges.


Subject(s)
COVID-19 , Influenza, Human , Disease Outbreaks , Humans , Influenza, Human/diagnosis , Influenza, Human/epidemiology , Long-Term Care , SARS-CoV-2
6.
J Clin Gastroenterol ; 52(1): 60-66, 2018 Jan.
Article in English | MEDLINE | ID: mdl-27875352

ABSTRACT

BACKGROUND: The aspartate aminotransferase-to-platelet ratio index (APRI) and a fibrosis index calculated using platelets (FIB-4) have been proposed as noninvasive markers of liver fibrosis. GOALS: To determine APRI/FIB-4 accuracy for predicting histologic liver fibrosis and evaluate whether incorporating change in index improves test accuracy in hepatitis C virus (HCV)-infected Alaska Native persons. STUDY: Using liver histology as the gold standard, we determined the test characteristics of APRI to predict Metavir ≥F2 fibrosis and FIB-4 to predict Metavir ≥F3 fibrosis. Index discrimination was measured as the area under the receiver operator characteristic curve. We fit a logistic regression model to determine whether incorporating change in APRI/FIB-4 over time improved index discrimination. RESULTS: Among 283 participants, 46% were female, 48% had a body mass index >30, 11% had diabetes mellitus, 8% reported current heavy alcohol use. Participants were infected with HCV genotypes 1 (68%), 2 (17%), or 3 (15%). On liver histology, 30% of study participants had ≥F2 fibrosis and 15% had ≥F3 fibrosis. The positive predictive value of an APRI>1.5/FIB-4>3.25 for identifying fibrosis was 77%/78%. The negative predictive value of an APRI<0.5/FIB-4<1.45 was 91%/87%. The area under the receiver operator characteristic curve of an APRI/FIB-4 for identifying fibrosis was 0.82/0.84. Incorporating change in APRI/FIB-4 did not improve index discrimination. CONCLUSIONS: The accuracy of APRI/FIB-4 for identifying liver fibrosis in HCV-infected Alaska Native persons is similar to that reported in other populations and could help prioritize patients for treatment living in areas without access to liver biopsy. Change in APRI/FIB-4 was not predictive of degree of fibrosis.


Subject(s)
Hepatitis C, Chronic , Liver Cirrhosis/diagnosis , Severity of Illness Index , Alaska , Aspartate Aminotransferases/blood , Cohort Studies , Female , Humans , Liver Cirrhosis/blood , Liver Cirrhosis/physiopathology , Longitudinal Studies , Male , Middle Aged , Platelet Count , Predictive Value of Tests
7.
Euro Surveill ; 23(40)2018 10.
Article in English | MEDLINE | ID: mdl-30301489

ABSTRACT

We summarised available hepatitis C virus (HCV) surveillance data for 2012-14 from Arctic/sub-Arctic countries/regions. We sent a HCV data collection template by email to public health authorities in all jurisdictions. Population statistics obtained from census sources for each country were used to estimate rates of reported acute and chronic/undifferentiated HCV cases. Seven countries with Arctic regions (Canada, Denmark, Finland, Greenland, Norway, Sweden and the United States, represented by the state of Alaska), including three Canadian territories and one province, as well as 11 Russian subnational Arctic regions, completed the data collection template. Data on acute HCV infection during 2014 was available from three Arctic countries and all Russian Arctic regions (rate range 0/100,000 population in Greenland, as well as Nenets and Chukotka Automous Okrugs (Russian subnational Arctic regions) to 3.7/100,000 in the Russian Republic of Komi). The rate of people with chronic/undifferentiated HCV infection in 2014 ranged from 0/100,000 in Greenland to 171.2/100,000 in Alaska. In most countries/regions, the majority of HCV-infected people were male and aged 19-64 years. Differences in surveillance methods preclude direct comparisons of HCV surveillance data between Arctic countries/regions. Our data can inform future efforts to develop standardised approaches to HCV surveillance in the Arctic countries/regions by identifying similarities/differences between the surveillance data collected.


Subject(s)
Hepacivirus , Hepatitis C/epidemiology , Population Surveillance/methods , Adult , Aged , Arctic Regions/epidemiology , Female , Humans , Male , Middle Aged , Prevalence , Young Adult
8.
J Phys Chem A ; 121(32): 5954-5966, 2017 Aug 17.
Article in English | MEDLINE | ID: mdl-28707899

ABSTRACT

A nitrosamine photooxidation reaction is shown to generate a peroxy intermediate by experimental physical-organic methods. The irradiation of phenyl and methyl-substituted nitrosamines in the presence of isotopically labeled 18-oxygen revealed that an O atom was trapped from a peroxy intermediate to trimethylphosphite or triphenylphosphine, or by nitrosamine itself, forming two moles of nitramine. The unstable peroxy intermediate can be trapped at low temperature in postphotolyzed solution in the dark. Chemiluminescence was also observed upon thermal decomposition of the peroxy intermediate, that is, when a postphotolysis low-temperature solution is brought up to room temperature. A DFT study provides tentative information for cyclic nitrogen peroxide species on the reaction surface.

9.
Mol Divers ; 21(2): 455-462, 2017 05.
Article in English | MEDLINE | ID: mdl-28058523

ABSTRACT

Substituted isoindoloquinolinones were obtained from N-aryl-3-hydroxyisoindolinones and aryl alkynes under Lewis acid-catalyzed conditions in 30-99% yields.


Subject(s)
Drug Design , Isoindoles/chemistry , Quinolones/chemistry , Quinolones/chemical synthesis
10.
J Pediatr ; 178: 206-213, 2016 Nov.
Article in English | MEDLINE | ID: mdl-27590612

ABSTRACT

OBJECTIVES: To evaluate the hepatocellular carcinoma (HCC) risk in Alaska Native children and young adults with hepatitis B virus (HBV). STUDY DESIGN: Retrospective analysis of a population-based cohort of Alaska Native persons with HBV followed during 1982-2012. All individuals with HBV were offered HCC screening regardless of age using alpha-fetoprotein every 6 months; persons with an elevated alpha-fetoprotein or persons at high-risk for HCC, such as cirrhosis, family history of HCC, were offered ultrasound. We calculated the HCC incidence/1000 person-years from date of cohort entry until death, diagnosis of HCC, or attaining the age of 40 years (males) or 50 years (females). RESULTS: We followed 1083 subjects with HBV (56% male) comprising 5 genotypes (A2 [12.5%], B6 [1.7%], C [5.3%], D [49.7%], F1 [18.6%], unknown [12.4%]) for a median of 23.4 years/person. We observed 22 HCC cases (incidence/1000 person-years follow-up: 1.0); 19 HCC cases among persons with genotype F1. There was no significant difference in HCC incidence between males (1.4) and females (0.6). The HCC incidence was significantly higher for persons with genotype F1 (4.4) compared with genotype A2 (0.4) and D (0.2) and remained higher among persons with HBV genotype F1 excluding persons with HCC family history/cirrhosis (1.9). CONCLUSIONS: Alaska Native children and young adults with HBV genotype F1 are at high risk for HCC and should receive HCC surveillance. For males <40 years of age and females <50 years of age with HBV in regions of the world with a high genotype F prevalence, testing/confirming genotype F can identify persons who could benefit from HCC surveillance.


Subject(s)
Carcinoma, Hepatocellular/ethnology , Hepatitis B virus/genetics , Hepatitis B/complications , Liver Neoplasms/ethnology , Adult , Carcinoma, Hepatocellular/virology , Child , Cohort Studies , Female , Genotype , Humans , Incidence , Liver Neoplasms/virology , Male , Retrospective Studies , Risk Factors , Young Adult , alpha-Fetoproteins
11.
Liver Int ; 36(10): 1507-15, 2016 10.
Article in English | MEDLINE | ID: mdl-27009849

ABSTRACT

BACKGROUND & AIMS: Most regions of the world have ≤3 co-circulating hepatitis B virus (HBV) genotypes, which limits direct comparisons of hepatocellular carcinoma (HCC) risk among HBV-infected persons by genotype. We evaluated HCC incidence by HBV genotype in a cohort of Alaska Native (AN) persons where five HBV genotypes (A, B, C, D, F) have been identified. METHODS: Our cohort comprised AN persons with chronic HBV infection identified during 1983-2012 who consented to participate in this study. Cohort persons were offered annual hepatitis B e antigen (HBeAg) testing and semi-annual HCC screening. We developed a logistic regression model to compare HCC risk by genotype, adjusting for age, sex, region and HBeAg status. RESULTS: Among the 1235 consenting study participants, 711 (57.6%) were male, 510 (41.3%) were HBeAg positive at cohort entry and 43 (3.5%) developed HCC. The HBV genotype was known for 1142 (92.5%) persons (13.5% A, 3.9% B, 6.7% C, 56.9% D, 19.0% F). The HCC incidence/1000 person-years of follow-up for genotypes A, B, C, D and F was 1.3, 0, 5.5, 0.4 and 4.2 respectively. Compared with persons with HBV genotype B/D infection, the HCC risk was higher for persons with genotypes A [adjusted odds ratio (aOR): 3.9, 95% confidence interval (CI): 1.14-13.74], C (aOR: 16.3, 95% CI: 5.20-51.11) and F (aOR: 13.9, 95% CI: 5.30-36.69). CONCLUSION: HBV genotype is independently associated with HCC risk. AN persons with genotypes A, C and F are at higher risk compared with genotypes B or D.


Subject(s)
Carcinoma, Hepatocellular/ethnology , Hepatitis B virus/genetics , Hepatitis B, Chronic/ethnology , Liver Neoplasms/ethnology , Adult , Aged , Female , Genotype , Hepatitis B e Antigens/blood , Hepatitis B, Chronic/complications , Humans , Incidence , Logistic Models , Male , Middle Aged , Odds Ratio , Retrospective Studies , United States/epidemiology
12.
Bioorg Med Chem Lett ; 26(9): 2198-205, 2016 May 01.
Article in English | MEDLINE | ID: mdl-27025339

ABSTRACT

Novel fluoroquinolone-pyrazine conjugates 7a-h with amino acid linkers were synthesized in good yields utilizing benzotriazole chemistry. Antimicrobial bioassay showed that the synthesized bis-conjugates have antimicrobial properties comparable to the parent drugs. Compound 7h showed superior antibacterial activity against Staphylococcus aureus and Streptococcus pyogenes (MIC=74.6 µM and 149.3 µM, respectively). This matched well with the estimated values obtained from 3D-pharmacophore and 2D-QSAR studies (MIC=67 µM and 92.9 µM, respectively).


Subject(s)
Anti-Bacterial Agents/chemistry , Fluoroquinolones/chemical synthesis , Piperazines/chemistry , Pyrazines/chemistry , Quinolines/chemistry , Amino Acids/chemical synthesis , Amino Acids/chemistry , Amino Acids/pharmacology , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/pharmacology , Fluoroquinolones/chemistry , Fluoroquinolones/pharmacology , Models, Molecular , Piperazines/chemical synthesis , Piperazines/pharmacology , Pseudomonas aeruginosa/drug effects , Pyrazines/chemical synthesis , Pyrazines/pharmacology , Quantitative Structure-Activity Relationship , Quinolines/chemical synthesis , Quinolines/pharmacology , Salmonella typhi/drug effects , Staphylococcus aureus/drug effects , Streptococcus pyogenes/drug effects , Triazoles/chemistry
13.
J Gen Intern Med ; 30(6): 742-8, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25605533

ABSTRACT

BACKGROUND: Patients with prior positive tuberculin skin test (TST) results may benefit from prophylaxis after repeat exposure to infectious tuberculosis (TB). OBJECTIVE: To evaluate factors associated with active TB disease among persons with prior positive TST results named as contacts of persons with infectious TB. DESIGN: Population-based retrospective cohort study. PARTICIPANTS: A total of 2,933 contacts with prior positive TST results recently exposed to infectious TB identified in New York City's TB registry during the period from January 1, 1997 through December 31, 2003. MAIN MEASUREMENTS: Contacts developing active TB disease ≤ 4 years after exposure were identified and compared with those who did not, using Poisson regression analysis. Genotyping was performed on selected Mycobacterium tuberculosis-positive isolates. KEY RESULTS: Among contacts with prior positive TST results, 39 (1.3 %) developed active TB disease ≤ 4 years after exposure (≤ 2 years: 34). Risk factors for contacts that were independently associated with TB were age < 5 years (adjusted prevalence ratio [aPR] = 19.48; 95 % confidence interval [CI] = 7.15-53.09), household exposure (aPR = 2.60;CI = 1.30-5.21), exposure to infectious patients (i.e., cavities on chest radiograph, acid-fast bacilli on sputum smear; aPR = 1.9 3; CI = 1.01-3.71), and exposure to a U.S.-born index patient (aPR = 4.04; CI = 1.95-8.38). Receipt of more than 1 month of treatment for latent TB infection following the current contact investigation was found to be protective (aPR = 0.27; CI = .08-0.93). Genotype results were concordant with the index patients among 14 of 15 contacts who developed active TB disease and had genotyping results available. CONCLUSIONS: Concordant genotype results and a high proportion of contacts developing active TB disease within 2 years of exposure indicate that those with prior positive TST results likely developed active TB disease from recent rather than remote infection. Healthcare providers should consider prophylaxis for contacts with prior TB infection, especially young children and close contacts of TB patients (e.g., those with household exposure).


Subject(s)
Contact Tracing , Mycobacterium tuberculosis/isolation & purification , Tuberculin Test , Tuberculosis, Pulmonary/epidemiology , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Humans , Infant , Infant, Newborn , Male , Middle Aged , New York City/epidemiology , Retrospective Studies , Risk , Tuberculosis, Pulmonary/prevention & control , Tuberculosis, Pulmonary/transmission , Young Adult
14.
Fish Physiol Biochem ; 41(1): 243-53, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25500770

ABSTRACT

Mineral needs as affected by changes in dietary protein and oil sources were studied in rainbow trout. Duplicate groups (n = 30 fish per replicate) of rainbow trout (initial BW: 37 g) were fed either a fish meal/fish oil-based (M) or a complete plant ingredient (V)-based diet at four graded ration (R) levels [apparent satiation (AS), R75, R50 and R25 % of AS]; one treatment group was maintained under starvation. The feeding trial lasted 12 weeks at a water temperature of 17 °C. Dietary intake, apparent digestibility and initial and final whole-body composition data were used to calculate mineral gain which was regressed against digestible mineral intake (both expressed as mg or µg kg(-0.8) day(-1)). Starvation loss (SL), endogenous loss of fed fish (ELF, y-intercept at x = 0) and point of intake for zero balance (PZB, x-intercept at y = 0) were used as estimates of maintenance requirements. SL provided the lowest estimate, ELF provided the net requirement of a mineral for maintenance and PZB provided the digestible dietary intake required to meet maintenance (SL < ELF < PZB). Dietary ingredient composition did not significantly affect the digestible mineral supply required for maintenance (PZB) for any of the minerals (P, Mg, K, Cu and Zn) studied. However, ELF of micro-minerals such as Cu and Zn were significantly affected. The ELF of Cu was significantly lower and that of Zn was significantly higher in V group compared with M-fed fish. Further studies on the effects of such changes in dietary formulations on micro-mineral metabolism are warranted.


Subject(s)
Animal Feed/analysis , Aquaculture/methods , Diet , Oncorhynchus mykiss/metabolism , Trace Elements/analysis , Animals , Digestion/physiology , Nutritional Requirements/physiology , Regression Analysis
15.
J Infect Dis ; 209(8): 1251-8, 2014 Apr 15.
Article in English | MEDLINE | ID: mdl-24273178

ABSTRACT

BACKGROUND: In 2010, a 13-valent pneumococcal conjugate vaccine (PCV13) replaced a 7-valent vaccine (PCV7) that contained all PCV7 serotypes plus 6 additional serotypes (PCV6+). We conducted annual surveys from 2008 to 2012 to determine the effect of PCV13 on colonization by pneumococcal serotypes. METHODS: We obtained nasopharyngeal swabs for pneumococcal identification and serotyping from residents of all ages at 8 rural villages and children age <60 months at 2 urban clinics. We conducted interviews/medical records review for all participants. RESULTS: A total of 18 207 nasopharyngeal swabs (rural = 16 098; urban = 2109) were collected. From 2008 to 2012, 84% of rural and 90% of urban children age <5 years were age-appropriately vaccinated with a PCV. Overall pneumococcal colonization prevalence remained stable among rural (66%) and urban (35%) children age <5 years, and adults age ≥18 years (14%). Colonization by PCV6+ serotypes declined significantly among rural children age <5 years, urban children age <5, and adults age ≥18 over the course of the study (25%-5%, 22%-9%, 22%-6%, respectively). CONCLUSIONS: PCV13 was rapidly introduced into the Alaska childhood immunization schedule and reduced colonization by PCV6+ serotypes among children. Unvaccinated adults also experienced comparable reductions in vaccine serotype colonization indicating substantial indirect protection from PCV13.


Subject(s)
Nasopharyngeal Diseases/prevention & control , Nasopharynx/microbiology , Pneumococcal Infections/prevention & control , Pneumococcal Vaccines/administration & dosage , Streptococcus pneumoniae/isolation & purification , Adolescent , Alaska/epidemiology , Child , Child, Preschool , Female , Humans , Male , Nasopharyngeal Diseases/epidemiology , Nasopharyngeal Diseases/microbiology , Pneumococcal Infections/epidemiology , Pneumococcal Infections/microbiology , Prevalence , Rural Population , Urban Population , Vaccination
16.
Article in English | MEDLINE | ID: mdl-38532601

ABSTRACT

AIM: This article describes the use of graphite(Gr) and boron carbide (B4C) as multiple nanoparticle reinforcements in LM25 aluminum alloy. Because boron carbide naturally absorbs neutron radiation, aluminium alloy reinforced with boron carbide metal matrix composite has gained interest in nuclear shielding applications. The primary goal of the endeavor is to create composite materials with high wear resistance, high microhardness, and high ultimate tensile strength for use in nuclear applications. BACKGROUND: Science and Technology have brought a vast change to human life. The human burden has been minimized by the use of innovation in developing new and innovative technologies. To improve the quality of human life, fresh, lightweight, and creative materials are being used, which play a vital role in science and technology and reduce the human workload. Composite materials made of metal are being used because they are lightweight. Neutron absorption, high ultimate strength, high wear resistance, high microhardness, high thermal and electrical conductivity, high vacuum environmental resistance, and low coefficient of thermal expansion under static and dynamic conditions are all demands for the hybrid metal matrix composites utilized in nuclear applications. OBJECTIVE: • Stir casting is used to create the novel LM 25 aluminum alloy/graphite and boron carbide hybrid nanocomposites. • The mechanical properties such as ultimate tensile strength, yield strength, percentage of elongation, microhardness, and wear behavior are calculated. • Three analyses are performed: microstructure, worn surface analysis, and fracture analysis of the tensile specimen. METHOD: • Stir casting process< • Tensile, Hardness, Wear Test • Materials Characterization - FESEM, Optical Microscopy, EDS< Results: The mechanical properties values are 308.76 MPa, 293.51 MPa, 7.8, 169.2 VHN, and 0.01854mm3/m intended for ultimate tensile strength, yield strength, percentage of elongation, microhardness, and wear behavior, respectively. This implies that the synthesized composite may be used in nuclear applications successfully. CONCLUSION: The subsequent explanation was drawn from this investigative work: • The LM 25/B4C/Gr hybrid nanocomposite was successfully manufactured by employing the stir casting technique. For nuclear shielding applications, these composites were prepared with three different weight percentages of nanoparticle reinforcements in 2,4,6% Boron carbide and constant 4 wt.% graphite. • The microhardness values of the three-hybrid nanocomposite fabricated castings were determined to be 143.4VHN, 156.7VHN, and 169.2VHN, respectively. • The hybrid nano composite's microstructure revealed that the underlying LM 25 aluminum alloy matrix's finegrained, evenly dispersed nanoparticles of graphite and boron carbide were present.

• The microtensile test was carried out and it was found that the ultimate tensile strength, yield strength and percentage of elongation values are 281.35MPa, 296.52MPa, 308.76MPa, 269.43, 274.69, 293.51 and 3.4, 5.7, 7.8 respectively.

• Deformation caused the hybrid LM 25/B4C/Gr nanocomposite to fracture in ductile mode. Dimples and cavities are seen in the fracture because of the nanoparticle reinforcements and the matrix's tight connection.

• The wear loss of nanocomposite based on the input parameter applied load, sliding velocity and sliding distance values are 0.02456, 0.02189, 0.01854, 0.02892, 0.02586, 0.02315 and 0.02682, 0.02254, 0.02015 mm3/m, respectively.

• The LM 25 alloy's elemental analysis displays the aluminum alloy phase as the largest peak and the remaining elements as smaller peaks; also, the spectral analysis reveals the presence of boron (B), graphite (C), silicon, and ferrous in the aluminum alloy LM 25.

• Through worn surface FESEM investigation, it was shown that under sliding and high load situations, debris, delamination, and groove develop. Further rupture, fine, and continuous grooves were seen when low stress and sliding circumstances were applied to the LM 25/B4C/Gr and stir cast specimen. This result implies the presence of mild adhesive and delamination wear processes.

.

17.
ACS Nano ; 18(14): 9942-9957, 2024 Apr 09.
Article in English | MEDLINE | ID: mdl-38552006

ABSTRACT

Highly efficient, cost-effective, and durable electrocatalysts, capable of accelerating sluggish reaction kinetics and attaining high performance, are essential for developing sustainable energy technologies but remain a great challenge. Here, we leverage a facile heterostructure design strategy to construct atomically thin Os@Pd metallenes, with atomic-scale Os nanoclusters of varying geometries confined on the surface layer of the Pd lattice, which exhibit excellent bifunctional properties for catalyzing both hydrogen evolution (HER) and oxygen reduction reactions (ORR). Importantly, Os5%@Pd metallenes manifest a low η10 overpotential of only 11 mV in 1.0 M KOH electrolyte (HER) as well as a highly positive E1/2 potential of 0.92 V in 0.1 M KOH (ORR), along with superior mass activities and electrochemical durability. Theoretical investigations reveal that the strong electron redistribution between Os and Pd elements renders a precise fine-tuning of respective d-band centers, thereby guiding adsorption of hydrogen and oxygen intermediates with an appropriate binding energy for the optimal HER and ORR.

18.
Nat Commun ; 15(1): 1550, 2024 Feb 20.
Article in English | MEDLINE | ID: mdl-38378733

ABSTRACT

Super-resolution techniques expand the abilities of researchers who have the knowledge and resources to either build or purchase a system. This excludes the part of the research community without these capabilities. Here we introduce the openSIM add-on to upgrade existing optical microscopes to Structured Illumination super-resolution Microscopes (SIM). The openSIM is an open-hardware system, designed and documented to be easily duplicated by other laboratories, making super-resolution modality accessible to facilitate innovative research. The add-on approach gives a performance improvement for pre-existing lab equipment without the need to build a completely new system.

19.
Adv Mater ; 35(12): e2208860, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36598813

ABSTRACT

Developing highly efficient multifunctional electrocatalysts is crucial for future sustainable energy  pursuits, but remains a great challenge. Herein, a facile synthetic strategy is used to confine atomically thin Pd-PdO nanodomains to amorphous Ru metallene oxide (RuO2 ). The as-synthesized electrocatalyst (Pd2 RuOx-0.5 h) exhibits excellent catalytic activity toward the pH-universal hydrogen evolution reaction (η10  = 14 mV in 1 m KOH, η10  = 12 mV in 0.5 m H2 SO4 , and η10  = 22 mV in 1 m PBS), alkaline oxygen evolution reaction (η10  = 225 mV), and overall water splitting (E10  = 1.49 V) with high mass activity and operational stability. Further reduction endows the material (Pd2 RuOx-2 h) with a promising alkaline oxygen reduction activity, evidenced by high halfway potential, four-electron selectivity, and excellent poison tolerance. The enhanced catalytic activity is attributed to the rational integration of favorable nanostructures, including 1) the atomically thin nanosheet morphology, 2) the coexisting amorphous and defective crystalline phases, and 3) the multi-component heterostructural features. These structural factors effectively regulate the material's electronic configuration and the adsorption of intermediates at the active sites for favorable reaction energetics.

20.
ACS Nano ; 17(11): 10733-10747, 2023 Jun 13.
Article in English | MEDLINE | ID: mdl-37196172

ABSTRACT

Highly efficient and durable electrocatalysts are of the utmost importance for the sustainable generation of clean hydrogen by water electrolysis. Here, we present a report of an atomically thin rhodium metallene incorporated with oxygen-bridged single atomic tungsten (Rh-O-W) as a high-performance electrocatalyst for pH-universal hydrogen evolution reaction. The Rh-O-W metallene delivers ascendant electrocatalytic HER performance, characterized by exceptionally low overpotentials, ultrahigh mass activities, excellent turnover frequencies, and robust stability with negligible deactivation, in pH-universal electrolytes, outperforming that of benchmark Pt/C, Rh/C and numerous other reported precious-metal HER catalysts. Interestingly, the promoting feature of -O-W single atomic sites is understood via operando X-ray absorption spectroscopy characterization and theoretical calculations. On account of electron transfer and equilibration processes take place between the binary components of Rh-O-W metallenes, fine-tuning of the density of states and electron localization at Rh active sites is attained, hence promoting HER via a near-optimal hydrogen adsorption.

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