Weighted Sobolev–Morrey Estimates for Nondivergence Degenerate Operators with Drift on Homogeneous Groups

Let X0,X1,…,Xq(qN) be real vector fields, which are left invariant on homogeneous group G, provided that X0 is homogeneous of degree two and X1,…,Xq are homogeneous of degree one. We consider the following nondivergence degenerate operator with drift L=∑i,j=1qaij(x)XiXj+a0(x)X0, where the coefficients aij(x), a0(x) belonging to vanishing mean oscillation space are bounded measurable functions. Furthermore, aij(x) satisfies the uniform ellipticity condition on Rq and a0(x)≠0. We obtain the local weighted Sobolev–Morrey estimates by applying the boundedness of commutators and interpolation inequalities on weighted Morrey spaces

Ordering of bimetallic nanoalloys predicted from bulk alloy phase diagrams

The Metropolis Monte Carlo method is used to demonstrate the relationship between the bulk phase diagram of alloys with limited miscibility and the equilibrium configurations of nanoparticles. Using the Au-Pt system as a case study, an embedded atom potential is parametrized so as to match the phase diagram exactly. The smooth temperature dependence of the short-range order parameter is shown correlated with an onion-like configuration intermediate between solid solution and phase separated states. © 2012 American Chemical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Global Hölder Estimates via Morrey Norms for Hypoelliptic Operators with Drift

Suppose that X0,X1,…,Xm are left invariant real vector fields on the homogeneous group G with X0 being homogeneous of degree two and X1,…,Xm homogeneous of degree one. In the paper we study the hypoelliptic operator with drift of the kind L=∑i,j=1maijXiXj+a0X0, where a0≠0 and (aij) is a constant matrix satisfying the elliptic condition on Rm. By proving the boundedness of two integral operators on the Morrey spaces with two weights, we obtain global Hölder estimates for L

Ordering and segregation in isolated Au-Pd icosahedral nanoclusters and nanowires and the consequences of their encapsulation inside carbon nanotubes

Metropolis Monte Carlo sampling in the semi-grand canonical ensemble with empirical potentials is used to predict equilibrium ordered structures and segregation properties of small icosahedral Au-Pd nanoclusters and helical nanowire segments over the whole range of compositions at low temperatures. The cases of free-standing clusters and wires are compared with the same systems encapsulated in carbon nanotubes. A number of chemically ordered structures and segregation states are identified and found to be consistent with the same interplay between size mismatch, mixing enthalpy and surface energies of elemental metals which determines the thermodynamic equilibrium of binary metal alloys. Encapsulation has the effect of modifying the surface energies of nanoclusters and wires, with considerable consequences on their thermodynamic states, although the metal-graphite interaction strength is low as compared with the metal cohesive energy and the carbon-carbon binding energy. © 2012 IOP Publishing Ltd.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Melting behaviour of gold nanowires in carbon nanotubes

The melting temperature and behaviour of gold nanowire in a single-walled carbon nanotube (SWNT) were investigated in detail using molecular dynamics simulations. The results showed that the melting temperature of the enclosed Au nanowire is lower than its bulk counterpart and higher than that observed for free-standing ones. Different from the melting behaviour of freestanding Au nanowires, the melting of Au nanowires enclosed in SWNTs with tube diameters (D) in the range 1.08 nm >D>2.09 nm investigated here was found to initiate from the centre layers. The predicted melting temperature and behaviour of gold nanowires in SWNTs were clearly shown to be dependent on the interaction between C and Au atoms. The interaction is helpful to further stabilize the structure of enclosed Au nanowires, in particular, the outermost layer. © 2011 Taylor & Francis.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Indoor Air Pollution and Human Perception in Public Buildings in Tianjin, China

AbstractIn recent years public health problems caused by indoor air pollution, such as Sick Building Syndrome (SBS), have been drawing strong public concerns. This study aims at investigating the indoor environment quality (IEQ) and people's perception in public buildings in Tianjin, China. Indoor environment parameters including air temperature, relative humidity, air speed, TVOC, formaldehyde and CO2 were monitored at two office buildings and two shopping malls, which located in Tianjin region. The measurement was done during January 2014-December 2014. Occupants’ perception on indoor air quality (IAQ), thermal environment, and SBS symptoms were surveyed by questionnaire. Approximately 31.5% and 2.5% of the samples in two offices exceeded the Chinese National Indoor Air Quality Standard for formaldehyde (0.08mg/m3), as well as 19.9% and 55.3% of samples in two shopping malls. High formaldehyde concentration, especially in the mall, should be of health effect concern. It was indicated that indoor air quality (IAQ) may lead to SBS symptoms in public building in Tianjin

Pet keeping in childhood and asthma and allergy among children in Tianjin area, China.

This study aims to find out the relationship between pet keeping in childhood and asthma and allergy among children aged 0-8 years old in Tianjin, China. Parental or guardians reports of 7360 children were analyzed. 1490 (21.6%) families kept pets at the time of the survey (current), among them 4.0% cats, and 14.7% dogs. For the first year of life of children (early), 1196 (18.4%) families kept pets, and among them 3.2% cats, and 13.7% dogs. Exposure to a pet in early childhood significantly increased the risk of current wheeze, current dry cough, and diagnosed rhinitis. 17.9% of parents reported an avoidance behavior, i.e., had removed or refrained a pet due to asthma or allergy in the family. After adjustment for avoidance behavior, the negative effect of pet keeping on children's health became even more obvious, with e.g. an AOR of 3.37 (1.58-7.19) for diagnosed asthma, 3.60 (2.07-6.27) for diagnosed rhinitis, 1.92 (1.31-2.81) for diagnosed eczema. A dose-response relationship between pet keeping at current and current wheeze, current eczema and diagnosed eczema was found. In conclusion, pet exposure in early life of children in Tianjin is a risk factor for asthma and allergies among children aged 0-8 years old

Phthalate Metabolites in Urine of Chinese Children and Their Association with Asthma and Allergic Symptoms

Phthalates are ubiquitous ‘modern’ chemical compounds with potential negative impacts on children’s health. A nested case–control study was designed to investigate associations of phthalate exposure with children’s asthma and allergic symptoms. We collected 243 first morning urine samples from 4–8-year-old children in Tianjin, China. Eight metabolites (i.e., mono-ethyl phthalate (MEP), mono-isobutyl phthalate (MiBP), mono-n-butyl phthalate (MnBP), mono-benzyl phthalate (MBzP) and mono-2-ethylhexyl phthalate (MEHP), mono-(2-ethyl-5-carboxylpentyl) phthalate (MECPP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP)) of five phthalates were analyzed using HPLC-MS. MiBP, MnBP and MECPP were the dominant phthalate metabolites in urine of children in Tianjin with median concentrations of 31.6 μg/L, 26.24 μg/L and 46.12 μg/L, respectively. We found significantly positive associations of diagnosed asthma with MnBP (adjusted odds ratios (AOR): 1.96; 95% confidence intervals (CIs): 1.07–3.61), MEHHP (AOR: 2.00; 95% CI: 1.08–3.71) and MEOHP (AOR: 2.09; 95% CI: 1.06–4.10). Our study indicates that phthalate exposure in childhood, especially to di-n-butyl phthalate (DnBP) and di(2-ethylhexyl) phthalate (DEHP), may be a risk factor for children’s asthma