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

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

How to summarise and report written qualitative data from patients: a method for use in cancer support care

Goals of work: Determination of key themes to aid the analysis of qualitative data collected at three cancer support centres in England, using the Measure Yourself Concerns and Wellbeing (MYCaW) questionnaire. Patients and methods: People with cancer who use complementary therapies experience and value a wide range of treatment effects, yet tools are urgently required to quantitatively measure these outcomes. MYCAW is an individualised questionnaire used in cancer support centres providing complementary therapies, scoring 'concerns or problems' and 'wellbeing' and collects qualitative data about other major events in a patient's life and what has been most important to the patient. Content analysis on 782 MYCaW questionnaires from people at these cancer support centres was carried out. The "concerns", "other things going on in their life" and "important aspects of centre" were thematically categorised, externally validated by a focus group and the inter-rater reliability calculated. Main results: Clinical information from a cancer patient's perspective was collected that is not measured on standard quality of life questionnaires; furthermore some themes acknowledge the multifaceted aspects of CAM provision, rather than information only relating to the therapeutic intervention. Categories for qualitative MYCaW analysis have been established providing a tool for future research and/or service delivery improvement within cancer support centres such as these. Conclusions: The established themes provide a framework to aid analysis of qualitative aspects of complementary therapy care for people with cancer, improving our understanding of how the patient’s cancer experience can be aided by complementary therapies in specialized cancer centres

Greater Oxygen Uptake and Respiratory Efficiency After 4 Weeks of Aerobic Exercise Utilizing Nasal Breathing

Engaging in routine aerobic exercise is essential to maintain a healthy respiratory performance. However, new evidence supports that utilizing nasal breathing (NB) over combined breathing (CB) during aerobic exercise sessions could provide greater respiratory adaptations due to its positive effect on alveolar gas exchange. PURPOSE: To determine what respiratory adaptations develop after 4 weeks of aerobic exercise utilizing NB in comparison to CB. METHODS: 22 men (21.55 ± 2.58 years) were randomized into the CB or NB group. Participants performed a pulmonary function test and a graded maximal aerobic exercise test (GXT) during Pre-training (V1), and after 4 weeks of supervised aerobic exercise sessions (Post-training, V2) using their assigned breathing condition. During the intervention, participants trained 4 times per week at a moderate intensity (65%-70% of their predicted maximal heart rate). Throughout the GXT, respiratory gases were collected with metabolic cart. A mixed between-within repeated measures ANOVA with Bonferroni corrections was utilized to analyze all data with a significance set at p \u3c 0.05 and partial eta squared reported as effect size. RESULTS: Throughout the GXT, but particularly at 70% of VO₂max, a significant change was observed in many respiratory variables for the NB group. For example, the NB group had a significant increase in tidal volume (Vt) from V1 to V2 [F(1, 20) = 6.256, p = 0.020, partial η² = 0.238), highlighting a greater (V1: 1.64 ± 0.38 L; V2: 2.03 ± 0.50 L) movement of air. At that same intensity, the NB group had a significant increase in the oxygen uptake [F(1, 20) = 5.374, p = 0.017, partial η2 = 0.212] and respiratory [F(1, 20) = 7.313, p = 0.009, partial η2 = 0.268] efficiency. Such as, after the intervention, the NB group was able to extract more oxygen (V1: 4.45 ± 0.56 %; V2: 5.07 ± 0.82 %) from the total air. In addition, per one breath, the NB group increased (V1: 0.91 ± 0.28 mL · kg· breath; V2: 1.30 ± 0.46 mL · kg · breath) how much oxygen they were able to mobilize. CONCLUSION: After 4 weeks of moderate-intensity aerobic exercise utilizing NB, our results suggest that NB is beneficial for improving respiratory performance. This improvement is evidenced by an increased amount of oxygen extracted from the total inhaled air and an increase in the total amount of air moved per breath. These significant adaptations over a relatively short period of 4 weeks suggests that a longer intervention could further amplify these benefits, as the respiratory system could undergo even greater adaptations with extended exposure to NB

Intercranial Blood Flow is Determined by Diastolic Blood Pressure

A deeper understanding of cerebral hemodynamics at rest is warranted to identify pathological changes associated with maladaptive changes in cognition. The need stems from evidence supporting cortical hypoperfusion during early adulthood as a predictor of late adulthood Alzheimer’s disease. PURPOSE: To disseminate which physiometrics can aid at identifying changes in cerebral blood flow. METHODS: A total of 22 young (22.55 ± 2.58 years) men participated in this study. Ultrasound sonography (doppler & pulse wave) was utilized to assess the peak systolic (PS) and end diastolic (ED) velocity (cm/s), while simultaneously measuring the vessel diameter (cm) in the internal (ICA) and external (ECA) carotid arteries. Blood flow volume (mL · min-1) for each artery was calculated [π(diameter/2)2 x velocity x 60] during PS and ED phases, and then used to calculate a hemodynamic ratio (ICA:ECA) between arteries. Fasted blood plasma was collected via antecubital venipuncture and utilized to quantify nitric oxide (NO), erythropoietin (EPO), phosphocreatine (PCr), and inorganic phosphate (Pi). The latter two were utilized to calculate a systemic surrogate (PCr:Pi) of metabolic status. Stepwise linear regression was utilized to identify the physiometrics affecting the ICA:ECA. An independent sample t-test was utilized to examine upper and lower 50th percentile comparisons within the ICA:ECA. All data was reported as mean ± standard deviation, with a statistical significance of p \u3c 0.05 and Cohen’s d reported as effect size. RESULTS: The linear regression explained 36.6% of the variability in the ICA:ECA [F(2,18) = 6.769, p = 0.006]. For every 1 unit increase in diastolic blood pressure (p = 0.048), the ICA:ECA decreased by 0.024 units, indicating a greater blood flow volume towards the ECA. In addition, for every 1 unit increase in the PCr:Pi (p = 0.036), the ICA:ECA decreased by 0.623 units, also indicating a greater blood flow volume towards the ECA. Stratified into upper and lower than 50th percentile of the ICA:ECA, groups became highly dichotomous with no distribution near the median. This comparison revealed a significant difference [t(20) = 3.233, p = 0.004, d = 3.01] in the ICA PS (upper: 924.92 ± 190.55 mL· min-1; lower: 676.15 ± 169.80 mL· min-1) blood volume. The significant difference [t(20) = 2.293, p = 0.033, d = 1.22] was also present in the ICA ED (upper: 305.52 ± 76.12 mL· min-1; lower: 234.09 ± 69.88 mL· min-1) blood volume. CONCLUSION: In young men, having a lower diastolic blood pressure is linked to a greater intracranial blood flow. Such hemodynamic predominance might indicate a greater metabolic demand at rest, explaining why a higher ICA blood volume coexisted with a lower PCr:Pi. Conducting continuous follow-ups throughout late adulthood is critical to identify the extent to which maintaining a controlled blood pressure is beneficial in preventing cortical hypoperfusion and associated cognitive decline

Enhancing Oxygen Uptake Efficiency Through Nasal Breathing in Aerobic Exercise

An individual’s ability to use oxygen to sustain aerobic performance, as denoted by the oxygen uptake efficiency (OUE), is calculated by dividing oxygen uptake (VO2) by ventilation (VE). Whether nasal breathing (NB) during exercise would improve OUE more significantly compared to combined breathing (CB) remains uncertain. PURPOSE: To determine the effects of utilizing NB during exercise on OUE. METHODS: Fourteen males (age: 20.57 ± 1.22 yrs; BMI: 26.03 ± 3.16 kg/m2) were randomly assigned to the NB (n = 8) or CB (n = 6) group for a 4-week supervised aerobic exercise intervention conducted four times per week for 30 minutes at moderate intensity (70% maximal heart rate). VO2max tests were performed during the pre- (week 0) and post-study (week 4) periods on a recumbent bike to determine the change in OUE, VO2, and VE at varying intensities (40%, 55%, 70%, 85%, and 100% of VO2max). The OUE was calculated as VO2 (L) ÷ VE (L). A one-way ANCOVA, controlling for OUE, VO2, and VE at pre-study, was utilized to examine if NB elicited cardiorespiratory adaptations that were superior to the CB training at post-study. A paired-sample t-test examined changes in OUE, VO2, and VE throughout the GXT from week 0 to week 4. Data are presented as mean ± standard error. RESULTS: The NB group demonstrated significantly greater [F(1,11) = 7.213, p = 0.021] OUE (0.048 ± 0.002) at 85% of VO2max than the CB (0.037 ± 0.003) group. Similarly, the NB group had a significantly greater (p = 0.014) OUE (0.025 ± 0.001) at 100% of VO2max than the CB (0.021 ± 0.001) group. Only the NB group experienced significant improvements after exercise training in VO2 at 40% ( p = 0.003, 12.02 ± 0.50 to 13.72 ± 0.59 mL·kg·min-1], 55% (p = 0.006, 16.68 ± 0.71 to 18.87 ± 0.81 mL·kg·min-1), 70% (p = 0.005, 21.16 ± 0.93 to 24.00 ± 1.01 mL·kg·min-1), 85% (p = 0.004, 25.81 ± 1.11 to 29.03 ± 1.23 mL·kg·min-1), and 100% VO2max (p = 0.005, 30.31 ± 1.30 to 34.18 ± 1.48 mL·kg·min-1). While not statistically significant, the NB group displayed a trend of reduced VE compared to the CB group. CONCLUSION: The integration of NB during aerobic exercise enhanced the OUE, particularly at higher intensities, compared to CB. This adaptation is noteworthy, as the NB group achieved a comparable range of VO2 as the CB group while maintaining a lower VE after just 1-month of training. This denotes that NB could promote enhanced oxygen movement. Future studies are warranted to investigate additional health adaptations resulting from such training benefits

Altered striatal endocannabinoid signaling in a transgenic mouse model of spinocerebellar ataxia type-3

Spinocerebellar ataxia type-3 (SCA-3) is the most prevalent autosomal dominant inherited ataxia. We recently found that the endocannabinoid system is altered in the post-mortem cerebellum of SCA-3 patients, and similar results were also found in the cerebellar and brainstem nuclei of a SCA-3 transgenic mouse model. Given that the neuropathology of SCA-3 is not restricted to these two brain regions but rather, it is also evident in other structures (e.g., the basal ganglia), we studied the possible changes to endocannabinoid signaling in the striatum of these transgenic mice. SCA-3 mutant mice suffer defects in motor coordination, balance and they have an abnormal gait, reflecting a cerebellar/brainstem neuropathology. However, they also show dystonia-like behavior (limb clasping) that may be related to the malfunction/deterioration of specific neurons in the striatum. Indeed, we found a loss of striatal projecting neurons in SCA-3 mutant mice, accompanied by a reduction in glial glutamate transporters that could potentially aggravate excitotoxic damage. In terms of endocannabinoid signaling, no changes in CB2 receptors were evident, yet an important reduction in CB1 receptors was detected by qPCR and immunostaining. The reduction in CB1 receptors was presumed to occur in striatal afferent and efferent neurons, also potentially aggravating excitotoxicity. We also measured the endocannabinoid lipids in the striatum and despite a marked increase in the FAAH enzyme in this area, no overall changes in these lipids were found. Collectively, these studies confirm that the striatal endocannabinoid system is altered in SCA-3 mutant mice, adding to the equivalent changes found in other strongly affected CNS structures in this type of ataxia (i.e.: the cerebellum and brainstem). These data open the way to search for drugs that might correct these changes.Funding: This study has been supported: (i) by MICINN (SAF2009-11847 and SAF2015-68580-C2-1-R), CIBERNED (CB06/05/0089) and “Fundación Eugenio Rodríguez Pascual”, to JFR; (ii) by the Research and Education Component of the Advancing a Healthier Wisconsin Endowment at the Medical College of Wisconsin, to CJH; and (iii) by Fundação para a Ciência e Tecnologia through the project POCI-01-0145-FEDER-016818 (PTDC/NEU-NMC/3648/2014) and co-financed by the Portuguese North Regional Operational Program (ON.2 – O Novo Norte) under the National Strategic Reference Framework (QREN), through the European Regional Development Fund (FEDER), to PM. Carmen Rodríguez-Cueto was a predoctoral fellow supported by FPI Program-Ministry of Science. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.info:eu-repo/semantics/publishedVersio

Authenticity of the Ratio of Inorganic Phosphate to Phosphocreatine as a Marker for Respiratory Stress During a Maximal Aerobic Exercise

Under the context of assessing the effects of mitochondrial stress on skeletal muscles, consideration for the ratio of inorganic phosphate to phosphocreatine (Pi:PCr) may be used as a surrogate marker. Furthermore, assessing the systemic Pi:PCr, under states of high metabolic and respiratory demands with reduced oxygen supply (VO2), such as strenuous exercise while only using nasal breathing (NB), might provide valuable information regarding respiratory strain to a given exercise bout. PURPOSE: To determine if the systemic assessment of the Pi:PCr ratio can serve as an indicator of respiratory stress. METHODS: Fourteen young males (age = 20.57 ± 1.22 yrs) completed a graded maximal exercise test (GXT) on a recumbent bike using either NB (n = 8) or combined (CB, n = 6) breathing. Plasma Pi and PCr were measured pre- and immediately post-GXT. Pi was analyzed using the malachite green colorimetric method, and PCr was quantified via sandwich enzyme-linked immunosorbent assay. The Pi:PCr was calculated by Pi ÷ PCr. A paired-sample t-test examined the Pi: PCr change following a GXT. A Pearson correlational analysis examined the relationship between the Pi:PCr and the respiratory performance during preset intensities (40%, 55%, 70%, 85%, and 100% VO2max). Data are presented as mean ± SD. RESULTS: The Pi:PCr ratio significantly decreased in the NB group (0.589 ± 0.313 to 0.530 ± 0.304, p = 0.034) mainly due to the elevated PCr (601.68 ± 318.88 mmol/L to 689.40 ± 410.60 mmol/L, p = 0.033). The Pi:PCR ratio was negatively correlated with VO2 only in the NB group throughout all preset intensities of the GXT. After controlling for the pre-GXT Pi:PCr as a covariate, the NB group showed a non-significant (p = 0.340) but higher mean concentration for post-exercise Pi:PCr compared to the CB group [NB: 0.451 ± 0.027 mmol/L versus CB: 0.407 ± 0.320 mmol/L. CONCLUSION: The results from the present study suggest that the assessment of the Pi:PCr ratio could serve as a valuable marker of physical strain pertaining to high respiratory demands. Moreover, the assignment of NB during exercise is becoming a novel method due to its postulated benefits towards respiratory function, which may induce a more significant cellular stress as denoted by an increase in the post-exercise Pi:PCr ratio

Integrating cache-related pre-emption delays into analysis of fixed priority scheduling with pre-emption thresholds

Cache-related pre-emption delays (CRPD) have been integrated into the schedulability analysis of sporadic tasks with constrained deadlines for fixed-priority pre-emptive scheduling (FPPS). This paper generalizes that work by integrating CRPD into the schedulability analysis of tasks with arbitrary deadlines for fixed-priority pre-emption threshold scheduling (FPTS). The analysis is complemented by an optimal threshold assignment algorithm that minimizes CRPD. The paper includes a comparative evaluation of the schedulability ratios of FPPS and FPTS, for constrained-deadline tasks, taking CRPD into account