Enrique Valderrama

Dataset from a research project that found that university students with non-normal BMI values (BMI < 18.5 or BMI > 25) experienced greater cardiac workload, as measured by the number of minutes per week spent with a heart rate greater than 50% max, even though they are less physically active, as measured by their daily step count.

This data (Age, MEQ, BMI) is from a of 384 university students enrolled in health and physical exercise (HPE) courses at a mid-sized university in the West South Central United States. The data are from a two-semester period (Fall 2019 & Spring 2020) and were collated and de-identified by members of the institutional research team before being given to the research team for analysis. This study does not include data from students who opted out (the default option), students with BMI values below 14.5 kg·m-2 or above 49.4 kg·m-2, and students whose age was below 16 or above 24.

<b>Demographics</b><br>This dataset contains data collected from 431 first-semester students enrolled in Oral Roberts University's success course entitled GEN 150 - Introduction to Whole Person Education during the Fall semester of 2019.<br><b>Variables</b><b><br></b><b>Age</b>. The age of the student, in years, on December 1, 2019.<br><b>Grit</b>. A measure of each student's "grit" using Duckworth et al.'s (2007) standard 12-question instrument.<br><b>Lifestyle</b>. Each student's lifestyle was measured using a 35-question lifestyle survey that has items that cover aspects of personal health care, drugs and alcohol use, physical fitness, psychological condition, spiritual condition, personal behavior, and nutrition.<br><b>MEQ</b>. A measure of each student's chronotype using the standard 19-item Morningness-Eveningness Questionnaire.<br><b>Sex</b>. The sex of the student, encoded as follows: "0" female, "1" male. Data were collected from 262 females (61%) and 169 males (39%).<br><b>Steps</b>. The average number of steps that students took per day as recorded by the Fitbit device.<br>

Background:  The chronotype of a person refers to an individual's natural sleep-wake cycle and whether that individual prefers morning or evening activities, and grit is an individual's perseverance and passion for long-term goals.Aim: The purpose of this study was to investigate the relationship between grit, chronotype, physical activity, and leading a healthy lifestyle in college-age students.Methods:  Health and fitness data (i.e., chronotype, grit, lifestyle assessment score, and daily steps) from 431 first-semester university students at a private college were collected and analyzed. Results: This study found that grit and chronotype both have significant correlations with living a healthy lifestyle and with physical activity. Grit more accurately predicts a person's lifestyle (β = -13.712, r = 0.39, p < 0.0001) while chronotype more accurately predicts the physical activity, or steps, of a person (β = 66.48, r = .19, p = .0001). Chronotype can also accurately p...

BackgroundHaving an abnormal body mass index (BMI) adversely affects cardiac workload and level of physical activity.ObjectiveTo examine the relationship between cardiac workload, physical activity, Sex, and BMI.MethodsThe number of steps taken per day (Steps) and minutes per week spent in targeted heart rate zones were collected from primarily first and second year university students (n = 1,801; 62% female) over a standard, 15-week long semester. Other data collected included BMI, Sex, Age, and Class Standing. Sex differences in BMI, Steps, and training heart rate zone (heart rates above 50% of max) minutes (THR) were evaluated, correlations between the study parameters were analyzed, and one-way ANOVA was used to test between competing models. The values p < .05 were considered statistically significant.ResultsStatistically significant (p < .05) differences between males and females were found for Steps, THR, and BMI. Males were more physically active but spent 18% less tim...

We present the fabrication of platinum (Pt0) nanoparticle (ca. 3 nm average diameter) decorated vertically aligned graphene (VG) screen-printed electrodes (Pt/VG-SPE) and explore their physicochemical characteristics and electrocatalytic activity towards the hydrogen evolution reaction (HER) in acidic media (0.5 M H2SO4). The Pt/VG-SPEs exhibit remarkable HER activity with an overpotential (recorded at – 10 mA cm–2) and Tafel value of 47 mV (vs. RHE) and 27 mV dec–1. These values demonstrate the Pt/VG-SPEs as significantly more electrocatalytic than a bare/unmodified VG-SPE (789 mV (vs. RHE) and 97 mV dec–1). The uniform coverage of Pt0 nanoparticles (ca. 3 nm) upon the VG-SPE support results in a low loading of Pt0 nanoparticles (ca. 4 µg cm–2), yet yields comparable HER activity to optimal Pt based catalysts reported within the literature, with the advantages of being comparatively cheap, highly reproducible and tailorable platforms for HER catalysis. In order to test any potentia...

Trends in the minimum number of credit hours required to complete a bachelor’s degree have been studied at four-year public institutions and appear to have been moving steadily towards a 120-hour standard for the majority of programs. The existence of such trends at Christian institutions have not previously been investigated nor has credit hour data been collected and made publicly available. If Christian institutions are not moving towards 120 hours, as state schools are, it could signal an emerging dichotomy in higher education requirements. This paper presents both the data and the trends in the minimum number of credit hours required to complete a bachelor’s degree at institutions who are members of the Council for Christian Colleges & Universities (CCCU). An analysis shows that Christian institutions are likewise reducing their degree requirements but at a slower pace than public four-year institutions.

ABSTRACT We report on the production of different types of sub-micron characteristic size carbon composite coatings, using high energy carbon ion beam irradiation of solid targets. The carbon ion beams of characteristic charge state C+ 4 and C+ 5 and energy in the 50 to 600 keV range, are produced in a 1.8 kJ, 160 kA plasma focus (PF) device operating in CH4, with a hollow anode. The interaction of the high energy carbon ion beams with different substrates, including silicon (100) and titanium, result in the formation of surface coatings, with different characteristic morphologies and compositions. In the case of a silicon substrate, a step bunched surface layer of hexagonal SiC or an amorphous carbon layer is formed, depending on the PF anode material, whereas, in the case of titanium, gradient layers of TiC with embedded carbon nanostructures are observed. Detailed characterizations of the different surface coatings have been conducted, using SEM, EDX, XRD, AFM, AES and Raman spectroscopy. The natural angular anisotropy of PF ion beams allows the effect of ion beam characteristic energy and flux on the resulting coatings to be investigated. On the base of the different morphologies and compositions of the resulting coatings an empirical model of PF induced deposition is discussed, which attributes the process to a combination of ion beam implantation and transient physical vapour deposition due to a plasma bubble ejected from the anode, as a result of high energy electron beam bombardment.

We have investigated the ion flux, ion energy and anisotropy of carbon ion emission, at different angular positions, from a low energy Plasma Focus (PF) device, operating in methane, at 20 kV, with 1.8 kJ stored energy. A detector array is used to measure simultaneously the ion beams at five different angles with respect to the PF axis (0°, 10°,

... [4] GY Chen, V. Stolojan, SRP Silva, H. Herman and S. Haq, Carbon 43 (2005), p. 704. Article | PDF (263 K) | View Record in Scopus | Cited By in Scopus (19). [5] I. Denysenko, J. Berndt, E. Kovacevic and I. Stefanovic, Phys. Plasmas 13 (2006), p. 073507. ...

ABSTRACT This paper reports on the production of carbon coatings onto a silicon substrate, using a lower power radiofrequency (RF) generator, combined with a plasma immersion ion implantation (PHI) driver. An RF, 13.6 MHz, generator operating at 30 W, was used to produce plasmas using a mix of C2H2 and H2 as feeding gas. In the experiments, a mirror polished silicon (100) substrate is exposed to the RF plasma for 20 m, being the sample holder biased through a PHI driver, operating in the 1 to 8 kV range, at 2 kHz. Different gas mixing ratios are used. Plasma properties are characterized using a single Langmuir probe and visible light spectroscopy. The morphology, structure and atomic composition of the resulting coatings are characterized using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, Raman spectroscopy (RS) and X-ray difraction (XRD). A detailed parameter scan of the resulting carbon coatings is presented, in correlation with the plasma properties which result in a given surface condition.

ABSTRACT Summary form only given. Among other features, the plasma focus (PF) is a well known source of energetic ion beams, of characteristic energy from hundreds of keV to tens of MeV. We have previously characterized the main features of ion beam emission in a low energy, 1.8 kJ, 160 kA Mather type PF device operating in methane. There we found that for the operational conditions of the PF, the dominant charge states of the carbon ions are C+4 and C+5, with maximum flux on axis of the order of 2ldr1022 ions/m2s, and characteristic energy in the 300 to 1000 keV. We have now investigated the effect of high energy PF carbon ion beams irradiation onto titanium targets. Pure titanium target were located at 0deg, 10deg, 15deg, and 25deg with respect to the PF axis, at 6 cm from the anode edge. The Ti samples were exposed to 50 shots of the PF, operating in methane, at 0.3 torr. The irradiated samples were analyzed with scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis and X-ray diffractometry (XRD). SEM images indicate for samples located at 10deg and 15deg, submicron size, closely packed regular structures form onto the Ti surface. At 0deg, the sample appears as a cracked surface, with some irregular isolated structures, whereas at 25deg, closely packed structures in the submicron size range are also observed, but with an irregular spatial distribution. The EDX analysis indicate the highest atomic carbon content in the irradiated samples corresponds to angular distribution between 10deg and 25deg. The XRD analysis shows that at 0deg the surface has an important content of TiC, which becomes lower at off-axis locations, where different carbon structures, including nanotubes, dominate. The strong angular dependence in surface morphology and composition is related to the axial distribution of carbon ion beams, which has been found to be of maximum energy on axis, but of higher flux in the 10deg to 15deg range. A- - detailed analysis of the correlations between the irradiated samples properties and the carbon ion beams features will be presented.

Plasma Focus (PF) discharges are known to produce pulsed high energy ion beams. We have performed an experimental study on the spatial distribution of the ion emission from a 1.8 kJ PF device operating in different gases. We have also conducted preliminary investigations on the interaction of these ion beams with different substrates. Simultaneous measurements at different angular directions for operation in methane indicate that the dominant charge states are H^+, C^+4 and C^+5, irrespective of the angular positions. The fluxes are maximum for the energy ranges 10--40 keV, 30--100 keV and 60-200 keV, for H^+, C^+4 and C^+5, respectively. Similar results are obtained with different gas fillings. The interaction of carbon ion beams with a silicon surface results in the formation of a surface layer of hexagonal silicon carbide, with embedded step/terraces structures. The result of the interaction of PF ion beams of different compositions with additional substrates will also be reported.

We report the investigation of high energy ion beam irradiation on titanium (Ti) substrates at room temperature using a low energy plasma focus (PF) device operating in methane gas. The surface modifications induced by the ion beam using two different anode materials, graphite and copper, are characterized using standard surface science diagnostic tools, such as x-ray diffraction, scanning electron microscopy,

An energetic condensation technique, cathodic arc discharge deposition, is used to grow epitaxial Niobium (Nb) thin films on a-plane sapphire (hexagonal-closed-packed Al2O3) at moderate substrate heating temperature (<400 °C). The epitaxial Nb(110)/Al2O3(1,1,-2,0) thin films reached a maximum residual resistance ratio (RRR) value 214, despite using a reactor-grade Nb cathode source whose RRR was only 30. The measurements suggest that the

We have investigated the ion flux, ion energy and anisotropy of carbon ion emission, at different angular positions, from a low energy Plasma Focus (PF) device, operating in methane, at 20 kV, with 1.8 kJ stored energy. A detector array is used to measure simultaneously the ion beams at five different angles with respect to the PF axis (0°, 10°,

ABSTRACT This paper reports on the production of carbon coatings onto a silicon substrate, using a lower power radiofrequency (RF) generator, combined with a plasma immersion ion implantation (PHI) driver. An RF, 13.6 MHz, generator operating at 30 W, was used to produce plasmas using a mix of C2H2 and H2 as feeding gas. In the experiments, a mirror polished silicon (100) substrate is exposed to the RF plasma for 20 m, being the sample holder biased through a PHI driver, operating in the 1 to 8 kV range, at 2 kHz. Different gas mixing ratios are used. Plasma properties are characterized using a single Langmuir probe and visible light spectroscopy. The morphology, structure and atomic composition of the resulting coatings are characterized using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, Raman spectroscopy (RS) and X-ray difraction (XRD). A detailed parameter scan of the resulting carbon coatings is presented, in correlation with the plasma properties which result in a given surface condition.

ABSTRACT Summary form only given. Among other features, the plasma focus (PF) is a well known source of energetic ion beams, of characteristic energy from hundreds of keV to tens of MeV. We have previously characterized the main features of ion beam emission in a low energy, 1.8 kJ, 160 kA Mather type PF device operating in methane. There we found that for the operational conditions of the PF, the dominant charge states of the carbon ions are C+4 and C+5, with maximum flux on axis of the order of 2ldr1022 ions/m2s, and characteristic energy in the 300 to 1000 keV. We have now investigated the effect of high energy PF carbon ion beams irradiation onto titanium targets. Pure titanium target were located at 0deg, 10deg, 15deg, and 25deg with respect to the PF axis, at 6 cm from the anode edge. The Ti samples were exposed to 50 shots of the PF, operating in methane, at 0.3 torr. The irradiated samples were analyzed with scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis and X-ray diffractometry (XRD). SEM images indicate for samples located at 10deg and 15deg, submicron size, closely packed regular structures form onto the Ti surface. At 0deg, the sample appears as a cracked surface, with some irregular isolated structures, whereas at 25deg, closely packed structures in the submicron size range are also observed, but with an irregular spatial distribution. The EDX analysis indicate the highest atomic carbon content in the irradiated samples corresponds to angular distribution between 10deg and 25deg. The XRD analysis shows that at 0deg the surface has an important content of TiC, which becomes lower at off-axis locations, where different carbon structures, including nanotubes, dominate. The strong angular dependence in surface morphology and composition is related to the axial distribution of carbon ion beams, which has been found to be of maximum energy on axis, but of higher flux in the 10deg to 15deg range. A- - detailed analysis of the correlations between the irradiated samples properties and the carbon ion beams features will be presented.

ABSTRACT We report on the production of different types of sub-micron characteristic size carbon composite coatings, using high energy carbon ion beam irradiation of solid targets. The carbon ion beams of characteristic charge state C+ 4 and C+ 5 and energy in the 50 to 600 keV range, are produced in a 1.8 kJ, 160 kA plasma focus (PF) device operating in CH4, with a hollow anode. The interaction of the high energy carbon ion beams with different substrates, including silicon (100) and titanium, result in the formation of surface coatings, with different characteristic morphologies and compositions. In the case of a silicon substrate, a step bunched surface layer of hexagonal SiC or an amorphous carbon layer is formed, depending on the PF anode material, whereas, in the case of titanium, gradient layers of TiC with embedded carbon nanostructures are observed. Detailed characterizations of the different surface coatings have been conducted, using SEM, EDX, XRD, AFM, AES and Raman spectroscopy. The natural angular anisotropy of PF ion beams allows the effect of ion beam characteristic energy and flux on the resulting coatings to be investigated. On the base of the different morphologies and compositions of the resulting coatings an empirical model of PF induced deposition is discussed, which attributes the process to a combination of ion beam implantation and transient physical vapour deposition due to a plasma bubble ejected from the anode, as a result of high energy electron beam bombardment.

... [4] GY Chen, V. Stolojan, SRP Silva, H. Herman and S. Haq, Carbon 43 (2005), p. 704. Article | PDF (263 K) | View Record in Scopus | Cited By in Scopus (19). [5] I. Denysenko, J. Berndt, E. Kovacevic and I. Stefanovic, Phys. Plasmas 13 (2006), p. 073507. ...

We report the investigation of high energy ion beam irradiation on titanium (Ti) substrates at room temperature using a low energy plasma focus (PF) device operating in methane gas. The surface modifications induced by the ion beam using two different anode materials, graphite and copper, are characterized using standard surface science diagnostic tools, such as x-ray diffraction, scanning electron microscopy,

An energetic condensation technique, cathodic arc discharge deposition, is used to grow epitaxial Niobium (Nb) thin films on a-plane sapphire (hexagonal-closed-packed Al2O3) at moderate substrate heating temperature (<400 °C). The epitaxial Nb(110)/Al2O3(1,1,-2,0) thin films reached a maximum residual resistance ratio (RRR) value 214, despite using a reactor-grade Nb cathode source whose RRR was only 30. The measurements suggest that the