Effects of Surface Roughness on the Electrochemical Reduction of CO2 over Cu

We have investigated the role of surface roughening on the CO2 reduction reaction (CO2RR) over Cu. The activity and product selectivity of Cu surfaces roughened by plasma pretreatment in Ar, O2, or N2 were compared with that of electrochemically polished Cu samples. Differences in total and product current densities, the ratio of current densities for HER (the hydrogen evolution reaction) to CO2RR, and the ratio of current densities for C2+ to C1 products depend on the electrochemically active surface and are nearly independent of plasma composition. Theoretical analysis of an electropolished and roughened Cu surface reveals a higher fraction of undercoordinated Cu sites on the roughened surface, sites that bind CO preferentially. Roughened surfaces also contain square sites similar to those on a Cu(100) surface but with neighboring step sites, which adsorb OC-COH, a precursor to C2+ products. These findings explain the increases in the formation of oxygenates and hydrocarbons relative to CO and the ratio of oxygenates to hydrocarbons observed with increasing surface roughness

Ultrafast laser welding of ceramics.

Welding of ceramics is a key missing component in modern manufacturing. Current methods cannot join ceramics in proximity to temperature-sensitive materials like polymers and electronic components. We introduce an ultrafast pulsed laser welding approach that relies on focusing light on interfaces to ensure an optical interaction volume in ceramics to stimulate nonlinear absorption processes, causing localized melting rather than ablation. The key is the interplay between linear and nonlinear optical properties and laser energy-material coupling. The welded ceramic assemblies hold high vacuum and have shear strengths comparable to metal-to-ceramic diffusion bonds. Laser welding can make ceramics integral components in devices for harsh environments as well as in optoelectronic and/or electronic packages needing visible-radio frequency transparency

CULTIVATION OF MICROALGAE FOR BIO OIL PRODUCTION AND CARBON DIOXIDE REMOVAL

The use of fossil fuel is now widely accepted as unsustainable due to depleting resource and the accumulation of greenhouse gases in the environment that have already exceeded the dangerously high threshold of 450ppm COre. To achieve environmental and economic sustainability, fuel production processes are required not only renewable but also capable of sequestering atmospheric COz. Microalgae are a versatile field due to its wide range of application and industries. It has been investigated that microalgae can be used for the production of a number of products ranging from fuel, pharmaceutical, food and health. In the fields of fuel and energy only microalgae can be used to produce biodiesel, bio-oil, bio-syngas and biohydrogen. Not limited by that, the production of microalgae can be couple with C02 mitigation and wastewater treatment. Development in microalgae cultivation and downstream processes are expected to further enhance cost effectiveness of the biofuel from microalgae. This research entitled "Cultivation of microalgae for biooil production and C02 removal" is done to investigate and to develop a microalgae cultivation system with the aim to improve the C02 removal and fixation during the cultivation of microalgae. The main objective of this research is to study on the cultivation technique(s) of microalgae specifically bioreactor, the C02 utilization of the system, potential species of microalgae system for both bio-oil production and C02 removal system as well as the optimum growth condition for cultivation of microalgae. The scope of study will be narrowed down to the growth rate and survival of microalgae species, utilization of wild algae for the mentioned purposes, the use of microalgae as biomass, the different technique for the production of microalgae and the C02 utilization technique using monoculture as well as mix-culture

Rapid turnover of effector-memory CD4(+) T cells in healthy humans

Memory T cells can be divided into central-memory (T(CM)) and effector-memory (T(EM)) cells, which differ in their functional properties. Although both subpopulations can persist long term, it is not known whether they are maintained by similar mechanisms. We used in vivo labeling with deuterated glucose to measure the turnover of CD4(+) T cells in healthy humans. The CD45R0(+)CCR7(-) T(EM) subpopulation was shown to have a rapid proliferation rate of 4.7% per day compared with 1.5% per day for CD45R0(+)CCR7(+) T(CM) cells; these values are equivalent to average intermitotic (doubling) times of 15 and 48 d, respectively. In contrast, the CD45RA(+)CCR7(+) naive CD4(+) T cell population was found to be much longer lived, being labeled at a rate of only 0.2% per day (corresponding to an intermitotic time of approximately 1 yr). These data indicate that human CD4(+) T(EM) cells constitute a short-lived cell population that requires continuous replenishment in vivo

Phase transitions and magnetic domain coexistence in Nd0.5Sr0.5MnO3 thin films

We present a study of the physical properties of perovskite oxide Nd0.5Sr0.5MnO3 (NSMO) thin films grown on (110)-oriented SrTiO3 substrates. In bulk form, NSMO displays coupled magnetic and electronic transitions from paramagnetic/insulator to ferromagnetic (FM)/metal and then to antiferromagnetic (AFM)/charge-ordered insulator with decreasing temperature. In thin films, the AFM ordering only occurs when the films exist in an anisotropic strain state such as those obtained on (110)-oriented cubic substrates. In this work, resonant X-ray reflectivity, soft X-ray photoemission electron microscopy (X-PEEM), and magnetometry measurements showed that the NSMO film displays both vertical and lateral magnetic phase separation. Specifically, the film consists of three layers with different density and magnetic properties. The FM and AFM properties of the main NSMO layer were probed as a function of temperature using soft X-ray magnetic spectroscopy, and the coexistence of lateral FM and AFM domains was demonstrated at 110 K using X-PEEM

Johnson, nature, and women : the early years

Critics enamoured of James Boswell's Life of Johnson have too frequently overlooked the empathy Samuel Johnson's work reveals toward women and other creatures of nature caught in the patriarchal web of eighteenth century domination. This dissertation focuses on Johnson's youthful poetry beginning with his earliest verse, "On a Daffodill," and concluding with London, his first major poem. These selections reveal his inability to resolve his role as a functioning male in a repressive society which discourages his desire for direct and nurturing relationships with women and nature that deal, not with heroic abstractions, but with personal involvement

Cognitive processes in depression : the effects of content and presentation variables on organization and recall

The purpose of the present research was to investigate the relationship between depressed affect and the organization and recall of positively and negatively valenced affective information. Experiment 1 examined the clustering and recall performance of inpatient depressives, psychiatric patients, and normals as a function of positive and negative words presented either randomly or in blocked fashion. Experiment 2 examined the recall performance of the same three groups of subjects as a function of positively and negatively valenced words that the subjects either rated or generated in an incidental recall task

Postmodernity and the History of African American Religious Representations: A Foucauldian Approach

African Americans' religious expression may be significantly related to social change and cultural shifts. African American Christians engaged in worship, praise, and practice, were probably immersed in a fluid interplay between religiosity and spirituality, within the context of a troublesome racial legacy. Writers often employ literature to deliver the experiences of people; therefore, it seems logical to examine the literary social elite when attempting to explore religion. This research concerns to what degree did religious and/or spiritual dialogue manifest in black literature from slavery to postmodernity. Foucault provides exemplary ways to interpret organic meaning-making within the context of life course experiences. Therefore, a Foucauldian approach was used to navigate the sensitive minefield that is black religion, expression, and spirituality. The findings suggest that from 1619 to 2006, religious and spiritual representations in literature seemed to reflect black's experiences with slavery, emancipation, civil rights and the black power movement, and postmodernity

Effects of visual field of presentation and stimulus characteristics on visual discrimination learning

The present study investigated the relationship between access to verbal processes and visual discrimination behavior. If reversal-shift behavior requires access to verbal processes, then response latencies should be shorter when sensory information has direct access to the areas concerned with these functions than when such information must travel indirectly to these areas. In accordance with the fact that language areas are primarily found in the left hemisphere of the normal, right-handed adult, stimuli were tachistoscopically presented to the right, center, and left visual fields. It was predicted that response latencies for nonverbal tasks during the initial discrimination should not be affected by visual field of presentation; verbal stimuli would result in shorter response latencies with right field presentation. During the reversal discrimination, both verbal and nonverbal stimuli should have shorter reaction times with right field presentation. Results indicate that during the initial discrimination, reaction times for verbal tasks were not affected by field of presentation; reaction times for nonverbal tasks were significantly higher with right field presentation. During the reversal discrimination, right field presentation resulted in significantly shorter response latencies for the size and name discriminations than did left field. Field of presentation, though a significant factor during both the initial and reversal / discriminations, accounted for a small proportion of the total variance