32,594 research outputs found
Kinetics and mechanism of formic acid decomposition on Ru(001)
The steady-state rate of decomposition of formic acid on
Ru(001) has been measured as a function of surface temperature, parametric in the pressure of formic acid. The
products of the decomposition reaction are C0_2, H_2, CO,
and H_2)0, i.e., both dehydrogenation and dehydration occur
on Ru (001). A similar product distribution has been observed on Ni(110), Ni(100), Ru(100), Fe(100), and
Ni(111) surfaces; whereas only dehydrogenation to C0_2
and H_2 occurs on the Cu(100), Cu(110), and Pt(111)
surfaces. Only reversible adsorption and desorption of formic acid is observed on the less reactive Ag(110) surface at low temperatures, whereas the more reactive Mo(100) surface is oxidized by formic acid at low temperatures with the products of this reaction being H_2, CO, and H_(2)O (Ref. 10). We report here the confirmation of earlier observations of the occurrence of both dehydrogenation and dehydration of formic acid on Ru(001), and more importantly, we provide a detailed mechanistic description of the steady-state decomposition reaction on this surface in terms of elementary steps
Calcium intake, physical activity and bone health status among Chinese early adolescents
The objective of this cross-sectional study was to determine the relationship between calcium
intake and physical activity with bone health status among Chinese early adolescents. A selfadministered
questionnaire was used to obtain socio-demographic background, family history of
osteoporosis, lifestyle practices and eating habits; while daily calcium intake was assessed using
one-day dietary recall and two-day dietary record. Physical activity was examined using PAQ-A
(Physical Activity Questionnaire for Adolescents). Height, weight and bone health status was
assessed using stadiometer, weighing scale (TANITA), and ultrasonometry QUS-2, respectively.
Data was analysed using the Statistical Package for Social Sciences (SPSS), version 15.0. A total of
236 Chinese subjects were recruited into this study. The mean age of subjects was 13.6 ± 0.5 years
old. Mean daily calcium intake was low, that is 573.4 ± 405.1mg. The mean score of PAQ-A was 2.14
± 0.64. Mean weight, height, and BMI were 50.9 ± 11.4kg, 1.62 ± 0.08m and 19.40 ± 3.72kg/m2,
respectively. Based on CDC classification of BMI-for-age (2000), 68.2% of subjects were in the
normal category, 16.1% were underweight, 11.4% were at risk of overweight and 4.2% overweight.
Mean Broadband Ultrasound Attenuation (BUA) was 77.55 ± 11.73dB/MHz. According to diagnostic
criteria for osteoporosis by WHO (1994), 49.2% of subjects had normal bone mass (t-score > -1.0),
more than half of the subjects were either osteopenic (49.6%) or osteopototic (1.3%). This might be
due to subjects being in the early adolescents state and their peak bone mass has yet to be attained.
T-test showed that there was significant difference between mean body weight among male and
female subjects. There was also significant higher mean BUA among female subjects than their
counterparts. Pearson correlation test showed that there was no significant relationship between
BUA with calcium intake (r= -0.05, p= 0.42) or physical activity (r= 0.03, p= 0.69). However, weight
had a significant positive correlation with BUA (r= 0.39, p<0.05). In conclusion, female subjects
have better bone health status as compared to males. Although no significant relationship was
shown between calcium intake and physical activity with bone health, these two factors are
known to reduce future risk of osteoporosis. It is recommended that prevention and management
of low bone mass should be focused on factors recognised as determinants of bone health status
among early adolescents. This is to ensure optimal bone health being attained among the young
population in reducing risk of osteoporosis in future
Unique gap structure and symmetry of the charge density wave in single-layer VSe
Single layers of transition metal dichalcogenides (TMDCs) are excellent
candidates for electronic applications beyond the graphene platform; many of
them exhibit novel properties including charge density waves (CDWs) and
magnetic ordering. CDWs in these single layers are generally a planar
projection of the corresponding bulk CDWs because of the quasi-two-dimensional
nature of TMDCs; a different CDW symmetry is unexpected. We report herein the
successful creation of pristine single-layer VSe, which shows a () CDW in contrast to the (4 4) CDW for the layers in
bulk VSe. Angle-resolved photoemission spectroscopy (ARPES) from the single
layer shows a sizable () CDW gap of 100 meV at the
zone boundary, a 220 K CDW transition temperature twice the bulk value, and no
ferromagnetic exchange splitting as predicted by theory. This robust CDW with
an exotic broken symmetry as the ground state is explained via a
first-principles analysis. The results illustrate a unique CDW phenomenon in
the two-dimensional limit
A staged approach with vincristine, adriamycin, and dexamethasone followed by bortezomib, thalidomide, and dexamethasone before autologous hematopoietic stem cell transplantation in the treatment of newly diagnosed multiple myeloma
Bortezomib-based regimens have significant activities in multiple myeloma (MM). In this study, we tested the efficacy of a total therapy with a staged approach where newly diagnosed MM patients received vincristine/adriamycin/dexamethsone (VAD). VAD-sensitive patients (≥75% paraprotein reduction) received autologous hematopoietic stem cell transplantation (auto-HSCT), whereas less VAD-sensitive patients (<75% paraprotein reduction) received bortezomib/thalidomide/dexamethasone (VTD) for further cytoreduction prior to auto-HSCT. On an intention-to-treat analysis, a progressive increase of complete remission (CR) rates was observed, with cumulative CR rates of 48% after HSCT. Seven patients progressed leading to three fatalities, of which two had central nervous system disease. The 3-year overall survival and event-free survival were 75.1% and 48.3%, respectively. Six patients developed oligoclonal reconstitution with new paraproteins. In the absence of anticoagulant prophylaxis, no patients developed deep vein thrombosis. The staged application of VAD+/–VTD/auto-HSCT resulted in an appreciable response rate and promising survivals. Our approach reduced the use of bortezomib without compromising the ultimate CR rate and is of financial significance for less affluent communities
Development of Self-Compacting Engineered Cementitious Composites
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/84749/1/iwscc_self-c_ecc_98.pd
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