Atomic resolution imaging of electrode surfaces in solutions containing reversible redox species

Procedures are described for insulating metal scanning tunneling microscope (STM) tips with either glass or polymer coatings. In solutions containing 0.10 M of a reversible redox couple, Fe(CN) - 3/-46 , the faradaic limiting current to polymer coated tips was 200–500 pA and that for glass coated tips was <10 pA. For polymer insulated tips, steady-state currents of 10–100 pA were observed at tip-sample displacements less than 0.3 µm. The suppression of faradaic current achieved by these coating procedures enabled the collection of the first atomic resolution STM images of highly ordered pyrolytic graphite electrodes in contact with redox-active electrolytes. Preliminary data for the in situ electrochemical characterization of these tips are also discussed

Design of a scanning tunneling microscope for electrochemical applications

A design for a scanning tunneling microscope that is well suited for electrochemical investigations is presented. The construction of the microscope ensures that only the tunneling tip and the sample participate in electrochemical reactions. The design also allows rapid replacement of the tip or sample, and enables facile introduction of auxiliary electrodes for use in electrochemical experiments. The microscope utilizes stepper motor driven approach mechanics in order to achieve fully remote operation and to allow reproducible coarse control of tip/sample spacings for electrochemical experiments. Highly ordered pyrolytic graphite images at atomic resolution in air and aqueous solutions can be obtained with this microscope

Produtividade de plantações de eucalipto intercaladas com espécies nativas em áreas de pastagens degradadas no noroeste do Estado do Paraná.

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Hygiene Sanitasi dan Keluhan Kesehatan Kulit Penghuni Rumah Kost Kelurahan Padang Bulan Selayang I Kecamatan Medan Selayang Tahun 2013

Hygiene, sanitation and health of skin complaints the residents of padang bulan village boarding selayang subdistrict medan selayang I. Complaints of skin health is one thing that is very often experienced by boarder, residents of the boarding school, boarding house residents and also in the form of a typical hives (morning, afternoon, evening or night) and the emergence of full-red swollen bumps on the surface of the skin and itch. Faizal research (2011), in the men\u27s dormitory USU percentage who experience health complaints of skin by 72,4%, the impact of the use of water sourced from the well bore, the behavior of self hygiene boarder who is still lacking, and love swapping clothes with friends This research aims to find out the hygiene sanitation and health of skin complaints the residents of Padang Bulan Village boarding Selayang Subdistrict Medan Selayang I. This research method is descriptive. The population is 536 people and the sample in this study was 100 people. Sampling was done by purposive sampling criteria respondents boarding house residents who have settled &gt;6 months. The results showed that respondents who experienced the health complaints of skin with a sense of the typical hives (morning, afternoon, or night) that as many as 38 people (38.0%), who experience health complaints of skin with red swollen bumps on the surface of the skin and itch that as many as 33 people (33,0%). The conclusions of this research are the complaints of skin health experienced by the occupants of a home boarding The village of Padang Bulan Selayang Subdistrict Medan Selayang I caused because of personal hygiene factors are unfavourable. Boarding house residents are advised to be more attention to personal hygiene and expected to home owners to pay more attention to kost basic sanitation home kost which includes water supply and means of garbage disposal

Fermiology and superconductivity studies on the non-tetrachalcogenafulvalene structured organic superconductor beta-(BDA-TTP)_2SbF_6

The quantum oscillatory effect and superconductivity in a non-tetrachalcogenafulvalene (TCF) structure based organic superconductor beta-(BDA-TTP)_2SbF_6 are studied. Here the Shubnikov-de Haas effect (SdH) and angular dependent magnetoresistance oscillations (AMRO) are observed. The oscillation frequency associated with a cylindrical Fermi surface is found to be about 4050 tesla, which is also verified by the tunnel diode oscillator (TDO) measurement. The upper critical field Hc2 measurement in a tilted magnetic field and the TDO measurement in the mixed state reveal a highly anisotropic superconducting nature in this material. We compared physical properties of beta-(BDA-TTP)_2SbF_6 with typical TCF structure based quasi two-dimensional organic conductors. A notable feature of beta-(BDA-TTP)_2SbF_6 superconductor is a large value of effective cyclotron mass m_c^*=12.4+/1.1 m_e, which is the largest yet found in an organic superconductor. A possible origin of the enhanced effective mass and its relation to the superconductivity are briefly discussed.Comment: 8 pages, 10 figure

From A-Level Success to College Achievement: The Mediating Effect of Academic Engagement on Cumulative Grade Point Average (CGPA) and Persistence among undergraduate students at Makerere University

The transition from high school to university is an important phase in the educational journey of many students. This stage not only serves as an access for university enrollment but also equips students to handle the challenges at university. This study investigates the influence of prior academic performance, as measured by A-level grades, on university cumulative grade point average (CGPA) and persistence to graduation while also exploring how academic engagement mediates this relationship. Using a post-positivist lens, sequential explanatory mixed-methods research design was applied, with emphasis on quantitative analysis of data and followed up by a qualitative analysis of data to explain the statistically significant results. The targeted population included final-year students from four participating schools at Makerere University, totaling 1,273 students. The study utilized a simple random sampling technique, allowing all final-year students from the four schools an equal chance to participate, which caused the realization of the final sample of 754. SPSS V26 was utilized to conduct correlation and regression analyses to explore the relationships and predictive power of A-level grades on college CGPA and persistence. Additionally, a mediation analysis was performed to assess the indirect effect of academic engagement on the link between A-level performance and university CGPA. The correlation findings indicated that A-level grades have a significant impact on students' cumulative grade point average (CGPA) but do not significantly affect their persistence in university. Consistent with prior research, academic involvement was found to significantly influence both CGPA and persistence. Additionally, the analysis showed no significant correlation between A-level grades and academic engagement, as well as an insignificant indirect effect of academic engagement on the relationship between A-level points and CGPA. To gain further insight into these statistically significant results, qualitative data collection and analysis were conducted using a purposive sampling method. Fourteen students voluntarily shared their experiences to elucidate the relationships, leading to the emergence of several key themes. For example, strong study skills, motivation, and intellectual ability were identified as reasons why students with higher A-level grades tend to achieve higher CGPA in university. Additionally, a solid grasp of concepts and increased confidence were highlighted as factors explaining why academic engagement positively predicts both CGPA and graduation persistence. Based on the findings, the study concluded that both A-level grades and academic engagement were critical factors toward university success. Therefore, the study recommended that Makerere University and other higher education institutions uphold the current A-Level cut-off requirements for admission into different university programs as may be deemed so. Besides, faculty members should prioritize creating an engaging learning environment that promotes interactive and meaningful experiences, utilizing methods such as collaborative learning sessions, projects, peer-to-peer interactions, and class presentations. By fostering this culture, students are more likely to excel academically and persist in their studies until graduation, as they will perceive their learning as both meaningful and rewarding

Potential Immune Health Benefits of Nasal Breathing Exercise on Inflammatory Cytokines in Plasma and Peripheral Blood Mononuclear Cells

Nasal breathing (NB) is gaining popularity in exercise routines to enhance performance and overall health. However, its effects on intracellular and extracellular inflammatory cytokines, which are crucial to the immune response, remain unclear. PURPOSE: This study examined the acute responses of pro- and anti-inflammatory cytokines in peripheral blood mononuclear cells (PBMCs – representing intracellular cytokines) and plasma (representing extracellular cytokines) following maximal aerobic exercise with NB. METHODS: Eleven physically healthy, sedentary men (age = 20.63±1.36, BMI=26.03±3.16 kg/m2, and VO2max = 32.60±6.46 mL/kg/min) were randomly assigned to either the NB (N=6) or the combined (control) breathing (CB, N=5) group. Both groups performed maximal aerobic exercise on a recumbent bike. Blood samples were collected in EDTA-containing vacutainer tubes before and immediately after maximal exercise to assess changes in pro- (IL-6 and IL-1β) and anti-inflammatory cytokines (IL-10) in plasma and PBMCs. PBMCs were isolated using density gradient centrifugation over Lymphoprep. RESULTS: The concentrations of intracellular cytokines were significantly lower than those of extracellular cytokines. For instance, the intracellular IL-6 was 1.92±1.55 pg/mL, while the extracellular IL-6 was 10.10±9.3 pg/mL (p=0.001). The intracellular IL-10 (2.55±1.41 pg/mL) was 7 times lower than the extracellular IL-10 (18.18±17.66 pg/mL, p=0.008), and the intracellular IL-1β was 0.80±0.82 pg/mL, whereas the extracellular IL-1β was 17.73±16.77 pg/mL (p=0.004). Although no differences were observed in IL-10 and IL-1β between the NB and CB groups following maximal exercise, the intracellular IL-6 was significantly lower (p=0.029) in the NB (1.24±1.27 pg/mL) than in the CB (2.79 ± 1.5 pg/mL) group. CONCLUSIONS: This study revealed that intracellular cytokine concentrations were lower than extracellular cytokine levels. This discrepancy likely results from the accumulation of secreted cytokines in plasma, derived from multiple cellular and tissue sources, systemic pooling, and the transient presence of cytokines within PBMCs. Additionally, the decrease in intracellular IL-1β levels following exercise with nasal breathing (NB) suggests potential immune health benefits. Further research is necessary to validate and extend these findings across various exercise modalities and diverse populations

Estimation of Visceral Fat via Ultrasound Sonography

Although visceral fat (VF) can be quantified via computed tomography or dual-energy X-ray absorptiometry (DXA), their application for frequent VF assessment is limited because both methods are radiating in nature. Research suggests that ultrasound imaging can be used to predict VF safely without the risk of radiation exposure. However, the complexity and/or lack of replicability limits such application. PURPOSE: To develop an easy-to-replicate ultrasound protocol and a regression model that can accurately estimate VF area (VFA, cm2). METHODS: Thirty healthy adults (9 males and 21 females, age: 23.2 ± 7.4 yr, body mass index: 22.3 ± 3.2 kg/m2, body fat percentage: 22.3 ± 5.9 %) fasted for 8 hours or more before a DXA scan and ultrasound imaging were performed to estimate VFA. Ultrasound imaging (with a 3.5-MHz convex-array probe) was used to measure the thickness of 15 different sites within the abdominal cavity. Thickness was defined as the distance in cm from the internal abdominal wall to the anterior aortic wall. Stepwise linear regression was utilized to develop a regression model for VFA using the estimated VFA by DXA as a dependent variable, followed by a Bland-Altman plot and Pearson correlation to compare the technique reliability. RESULTS: The developed regression model (F(4, 25) = 46.869, p = 0.001) was (37.677 + (1.456*Age) - (26.963*Sex) - (11.336*VFT2) + (13.554*VFT4)), where age = years, sex: 1 = male or 2 = female, and VFT2/4 = ultrasound probe placement 2 cm to the left (VFT2) and right (VFT4) of the superior umbilical border, respectively. The regression model had high accuracy (adjusted R2 = 0.864) and test reliability (r = 0.927, p = 0.001) at estimating VFA (31.4 ± 21.4 cm2) when compared to the VFA (31.1 ± 21.1 cm2) estimated by DEXA. CONCLUSION: Visceral fat area can be accurately estimated using an easy-to-replicate ultrasound protocol and regression model that eliminates the exposure to radiation caused by other body scanning methods

Acute Bout of Exercise May Preserve Peripheral Blood Mononuclear Cell Viability Under Oxidative Stress

Nasal breathing (NB) during exercise induces hypercapnic conditions, which may improve exercise performance. However, the impact of NB on cell viability (CV) remains unexplored. PURPOSE: This study investigated the effects of a single bout of exercise with NB on CV following lipopolysaccharide (LPS)-induced oxidative stress in peripheral blood mononuclear cells (PBMCs). METHODS: Twelve men (age=22.5±3.03 years) were randomly assigned to either the NB group (N=6) or the combined breathing (oral + nasal breathing, CB, N=6) group. Each group performed a graded maximal exercise test (GXT) on a recumbent bike. Plasma samples were collected before and immediately after the GXT to isolate PBMCs, followed by culturing for 12 hours, either with LPS (1µg/mL) or without LPS stimulation. RESULTS: There were no significant differences in CV between the NB and CB groups. CV did not differ between pre-exercise (92.78±1.52%) and immediately post-exercise (93.33±1.76%). However, after 12 hours of culture without LPS, CV was significantly lower in the immediately post-exercise condition (90.60±1.87%) than in the pre-exercise condition (93.45±1.49%, p=0.01). When stimulated with LPS and cultured for 12 hours, CV between the pre-exercise (90.16±2.04%) and immediately post-exercise conditions (91.70±1.50%) was not significantly different. However, both pre-exercise and immediately post-exercise CVs with LPS stimulation were significantly lower (p=0.029) than the pre-exercise CVs without LPS stimulation. CONCLUSION: Decreased CV following maximal exercise may be associated with exercise-induced physiological and biochemical stressors, such as reactive oxygen species, pro-inflammatory cytokines, and metabolic byproducts. Although CV decreased under oxidative stress conditions, a single bout of exercise showed a tendency to preserve viability, which may be attributed to exercise-induced reduction in susceptibility to LPS-induced viability loss by enhancing anti-inflammatory pathways and antioxidant defenses