Self-degradable Cementitious Sealing Materials

A self-degradable alkali-activated cementitious material consisting of a sodium silicate activator, slag, Class C fly ash, and sodium carboxymethyl cellulose (CMC) additive was formulated as one dry mix component, and we evaluated its potential in laboratory for use as a temporary sealing material for Enhanced Geothermal System (EGS) wells. The self-degradation of alkali-activated cementitious material (AACM) occurred, when AACM heated at temperatures of {ge}200 C came in contact with water. We interpreted the mechanism of this water-initiated self-degradation as resulting from the in-situ exothermic reactions between the reactants yielded from the dissolution of the non-reacted or partially reacted sodium silicate activator and the thermal degradation of the CMC. The magnitude of self-degradation depended on the CMC content; its effective content in promoting degradation was {ge}0.7%. In contrast, no self-degradation was observed from CMC-modified Class G well cement. For 200 C-autoclaved AACMs without CMC, followed by heating at temperatures up to 300 C, they had a compressive strength ranging from 5982 to 4945 psi, which is {approx}3.5-fold higher than that of the commercial Class G well cement; the initial- and final-setting times of this AACM slurry at 85 C were {approx}60 and {approx}90 min. Two well-formed crystalline hydration phases, 1.1 nm tobermorite and calcium silicate hydrate (I), were responsible for developing this excellent high compressive strength. Although CMC is an attractive, as a degradation-promoting additive, its addition to both the AACM and the Class G well cement altered some properties of original cementitious materials; among those were an extending their setting times, an increasing their porosity, and lowering their compressive strength. Nevertheless, a 0.7% CMC-modified AACM as self-degradable cementitious material displayed the following properties before its breakdown by water; {approx}120 min initial- and {approx}180 min final-setting times at 85 C, and 1825 to 1375 psi compressive strength with 51.2 to 55.0% porosity up to 300 C

Central Blood Pressure and Peripheral Reactive Vasodilation in Plant-Based and Typical Dieting African Americans

African American individuals (AA) face higher mortality rates from cardiovascular disease than Americans from other racial/ethnic backgrounds. The cause of this health disparity is multifactorial and is in part related to impaired vascular function as well as other variables including diet and numerous socioeconomic factors. Diets rich in whole plant foods and low in animal products may protect blood vessels through their high antioxidant capacity and low inflammatory load. PURPOSE: The purpose of this study was to test the hypothesis that AA adhering to a 100% plant-based (vegan) diet (PBD) would have a more favorable dietary intake of several key nutrients and more optimal blood cholesterol, which would contribute to better blood pressure and peripheral reactive vasodilation relative to AA following a typical American diet (TAD). METHODS: Seventeen AA participated in the study. Of them, 8 (5 female; age: 25±2 years; BMI: 23.4±1.4 kg/m2) were following a PBD for 2.5±0.3 years and 9 (5 female; age: 21±1 years; BMI: 25.3±2.1 kg/m2) were following a TAD. A fasting venous blood draw was performed to assess blood lipids. Participants completed a comprehensive diet questionnaire (DHQIII, NIH). Peripheral and central blood pressures were measured via the SphygmoCor system (AtCor Medical). Brachial artery flow-mediated dilation (FMD) and reactive hyperemia (RH) were assessed via well-established procedures. Briefly, 2 min baseline measurements of brachial artery diameter and blood velocity were taken via Doppler ultrasound before a forearm cuff was inflated to 220 mmHg for 5 min. Post-occlusion data were recorded for 3 min. Measurement of baseline to peak post-occlusion brachial artery diameter and blood velocity were performed by pairing a video capture system (Elgato) with edge-detection and blood velocity-tracking software (Quipu). RESULTS: PBD AA consumed more dark green vegetables and whole grains and less cholesterol than TAD AA (p\u3c.05 for all). Consumption of sodium, potassium, and vitamins C & E was not different between groups (p\u3e.05 for all). Total (TC) and low-density lipoprotein (LDL-C) blood cholesterol concentrations were lower in PBD AA relative to TAD AA (TC: 136±9 vs. 174±12 mg/dl; LDL-C: 77±6 vs. 106±11 mg/dl; respectively; p\u3c.05 for both). Resting brachial (b) and central (c) mean arterial blood pressures (MAP) were lower in PBD AA relative to TAD AA (bMAP: 85±2 vs. 91±2 mmHg; cMAP: 80±2 vs. 87±2 mmHg; respectively; p\u3c.05 for both). There were no differences between groups in FMD nor RH (p\u3e.05 for all). FMD and FMD/shear rate were 7.7±0.8% and 0.33±0.05 au in PBD AA and 6.2±0.9% and 0.27±0.03 au in TAD AA, respectively. For RH, the percentage change in blood velocity and flow were 1441±479% and 1425±466% in PBD AA and 707±495% and 671±76% in TAD AA, respectively. CONCLUSION: These preliminary data suggest that a diet rich in whole plant foods but devoid of animal products may be associated with healthier blood cholesterol and peripheral and central blood pressures in AA but that these differences may not yet be translating to differences in peripheral reactive vasodilation

Infant cortex responds to other humans from shortly after birth

A significant feature of the adult human brain is its ability to selectively process information about conspecifics. Much debate has centred on whether this specialization is primarily a result of phylogenetic adaptation, or whether the brain acquires expertise in processing social stimuli as a result of its being born into an intensely social environment. Here we study the haemodynamic response in cortical areas of newborns (1–5 days old) while they passively viewed dynamic human or mechanical action videos. We observed activation selective to a dynamic face stimulus over bilateral posterior temporal cortex, but no activation in response to a moving human arm. This selective activation to the social stimulus correlated with age in hours over the first few days post partum. Thus, even very limited experience of face-to-face interaction with other humans may be sufficient to elicit social stimulus activation of relevant cortical regions

Shallow stratigraphic control on pockmark distribution in north temperate estuaries

This paper is not subject to U.S. copyright. The definitive version was published in Marine Geology 329-331 (2012): 34-45, doi:10.1016/j.margeo.2012.09.006.Pockmark fields occur throughout northern North American temperate estuaries despite the absence of extensive thermogenic hydrocarbon deposits typically associated with pockmarks. In such settings, the origins of the gas and triggering mechanism(s) responsible for pockmark formation are not obvious. Nor is it known why pockmarks proliferate in this region but do not occur south of the glacial terminus in eastern North America. This paper tests two hypotheses addressing these knowledge gaps: 1) the region's unique sea-level history provided a terrestrial deposit that sourced the gas responsible for pockmark formation; and 2) the region's physiography controls pockmarks distribution. This study integrates over 2500 km of high-resolution swath bathymetry, Chirp seismic reflection profiles and vibracore data acquired in three estuarine pockmark fields in the Gulf of Maine and Bay of Fundy. Vibracores sampled a hydric paleosol lacking the organic-rich upper horizons, indicating that an organic-rich terrestrial deposit was eroded prior to pockmark formation. This observation suggests that the gas, which is presumably responsible for the formation of the pockmarks, originated in Holocene estuarine sediments (loss on ignition 3.5–10%), not terrestrial deposits that were subsequently drowned and buried by mud. The 7470 pockmarks identified in this study are non-randomly clustered. Pockmark size and distribution relate to Holocene sediment thickness (r2 = 0.60), basin morphology and glacial deposits. The irregular underlying topography that dictates Holocene sediment thickness may ultimately play a more important role in temperate estuarine pockmark distribution than drowned terrestrial deposits. These results give insight into the conditions necessary for pockmark formation in nearshore coastal environments.Graduate support for Brothers came from a Maine Economic Improvement Fund Dissertation Fellowship

Sympathetically-Mediated Cutaneous Vasoconstriction Is Similar Between Non-Hispanic Black and White Individuals

Cardiovascular disease (CVD) prevalence is highest in non-Hispanic Black (BL) individuals compared to any other race. The mechanisms responsible remain incompletely understood and can be impacted by several environmental, psychosocial, and socioeconomic factors. A major contributing factor to elevated CVD risk/prevalence in the BL population is altered vascular function, which could be attributed to an exaggerated vasoconstrictor response to efferent sympathetic activity (i.e., sympathetic vascular transduction). Previous data from our group demonstrates heightened sympathetic vascular transduction in the peripheral vasculature of BL males. However, whether sympathetically-mediated vasoconstriction is exaggerated in the cutaneous circulation of BL individuals remains unknown. PURPOSE: This study tested the hypothesis that BL individuals exhibit exaggerated vasoconstriction to intra-dermal infusions of the α-adrenoreceptor agonist norepinephrine (NE) relative to White (WH) individuals. METHODS: In this study, young, healthy college-aged BL (n=13; 6 females) and WH (n=10; 4 females) individuals participated. Participants were instrumented with an intradermal microdialysis membrane in the dorsal forearm. Red blood cell flux was continuously assessed via laser Doppler flowmetry before (baseline) and during incrementally stronger infusions of NE (10-8 M – 10-2 M; 6 min/dose). Data were analyzed as a relative (i.e., percent) reduction in cutaneous vascular conductance (CVC: flux/MAP) compared to the pre-infusion baseline. RESULTS: NE caused a dose-dependent reduction in CVC in both groups (P\u3c0.001). There was no difference between the BL and WH individuals (P=0.37) nor was there a race x dose interaction (P=0.84). Similarly, when the data were separated by sex there was no difference between BL and WH males (P=0.56) or females (P=0.26). CONCLUSION: Vasoconstrictor responsiveness to α-adrenoreceptor activation was similar between BL and WH individuals. These data suggest that the cutaneous circulation may exhibit divergent sympathically-mediated vasoconstrictor responsiveness relative to other peripheral vascular beds in BL individuals

Soft Templating and Disorder in an Applied 1D Cobalt Coordination Polymer Electrocatalyst

Disordered materials with resilient and soft-templated functional units bear the potential to fill the pipeline of robust catalysts for renewable energy storage. However, for novel materials lacking long-range order, the ability to discern local structure with atomic resolution still pushes the boundaries of current analytical and modeling approaches. We introduce a two-pillar strategy to monitor the formation and unravel the structure of the first disordered onedimensional cobalt coordination polymer catalyst, Co-dppeO2. This target material excels through proven high performance in commercial alkaline electrolyzers and organic transformations. We demonstrate that the key architecture behind this activity is the unconventional embedding of hydrated {H2O-Co2(OH)2-OH2} edge-site motifs, nested into a flexible organic matrix of highly oxidized and bridging hydrophobic dppeO2 ligands. Our combination of in situ spectroscopy and computational modeling of X-ray scattering and absorption spectra, backed with complementary experimental techniques, holds the key to understanding the atomic-range structure of important disordered materials

Activator of G protein signaling 3 is a guanine dissociation inhibitor for Galpha i subunits

Activator of G protein signaling 3 (AGS3) is a newly identified protein shown to act at the level of the G protein itself. AGS3 belongs to the GoLoco family of proteins, sharing the 19-aa GoLoco motif that is a Gαi/o binding motif. AGS3 interacts only with members of the Gαi/o subfamily. By surface plasmon resonance, we found that AGS3 binds exclusively to the GDP-bound form of Gαi3. In GTPγS binding assays, AGS3 behaves as a guanine dissociation inhibitor (GDI), inhibiting the rate of exchange of GDP for GTP by Gαi3. AGS3 interacts with both Gαi3 and Gαo subunits, but has GDI activity only on Gαi3, not on Gαo. The fourth GoLoco motif of AGS3 is a major contributor to this activity. AGS3 stabilizes Gαi3 in its GDP-bound form, as it inhibits the increase in tryptophan fluorescence of the Gαi3-GDP subunit stimulated by AlF4−. AGS3 is widely expressed as it is detected by immunoblotting in brain, testis, liver, kidney, heart, pancreas, and in PC-12 cells. Several different sizes of the protein are detected. By Northern blotting, AGS3 shows 2.3-kb and 3.5-kb mRNAs in heart and brain, respectively, suggesting tissue-specific alternative splicing. Taken together, our results demonstrate that AGS3 is a GDI. To the best of our knowledge, no other GDI has been described for heterotrimeric G proteins. Inhibition of the Gα subunit and stimulation of heterotrimeric G protein signaling, presumably by stimulating Gβγ, extend the possibilities for modulating signal transduction through heterotrimeric G proteins

Optical Propagation and Communication

Contains an introduction and reports on four research project.Maryland Procurement Office Contract MDA 904-90-C-5070Charles S. Draper Laboratories Contract DL-H-441698National Institute of Standards and Technology Grant 60-NANBOD-1052U.S. Army Research Office Grant DAAL03-90-G-0128U.S. Navy - Office of Naval Research Grant N00014-89-J-1163U.S. Air Force - Office of Scientific Research Contract F49620-90-C-003