Heavy metals in paddy fields in Taiwan: chemical behavior in soil and uptake by brown rice

Levels of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) were measured in 19 individual paddy fields in Taiwan. Total, reactive, and available metal levels were measured using Aqua Regia, 0.43 N HNO3, 0.1 M HCl, 0.05 M EDTA and 0.01 M CaCl2. Total metal levels ranged from below background levels to polluted and were highly heterogeneous across most fields. In general levels of metals in the soil decreased with an increase in distance from the water inlet which suggests that most metals originate from the irrigation water. Availability as measured by 0.01 M CaCl2 could be predicted well (Cd, Ni, Zn) by a Freundlich model similar to the one used in non-tropical soils. The fit of models for Cu and Pb was poor due to the lack of data on dissolved organic carbon (DOC). For Cr no fit was obtained at all. Uptake of Cd by rice was highly correlated to the availability as measured by CaCl2. Uptake models based on either the CaCl2 extractable Cd and Zn in soil solution, or a combination of the reactive Cd content in combination with pH and CEC proved equally suitable to predict Cd in rice. The impact of pH and, to a lesser extent, CEC urges the need to considere both properties when deriving soil quality standards (SQS). Uptake by rice by Indica species was markedly higher than that of Japonica although uptake by roots proved to be similar between both species. This suggests that differences between Japonica and Indica are more related to internal redistribution rather than differences in root uptake processes. Using the models, user friendly tools are designed allowing farmers and policy makers alike to evaluate the quality of the soil for a specific cultivar. This allows for a more accurate assessment of the suitability of the soil to be used for rice cropping compared to present soil standards based on Aqua Regia or HCl. As such the approach can be transferred easily to other countries as well based on a limited number of field tests

Nonleptonic Weak Decays of Bottom Baryons

Cabibbo-allowed two-body hadronic weak decays of bottom baryons are analyzed. Contrary to the charmed baryon sector, many channels of bottom baryon decays proceed only through the external or internal W-emission diagrams. Moreover, W-exchange is likely to be suppressed in the bottom baryon sector. Consequently, the factorization approach suffices to describe most of the Cabibbo-allowed bottom baryon decays. We use the nonrelativistic quark model to evaluate heavy-to-heavy and heavy-to-light baryon form factors at zero recoil. When applied to the heavy quark limit, the quark model results do satisfy all the constraints imposed by heavy quark symmetry. The decay rates and up-down asymmetries for bottom baryons decaying into $(1/2)^++P(V)$ and $(3/2)^++P(V)$ are calculated. It is found that the up-down asymmetry is negative except for $\Omega_b \to (1/2)^++P(V)$ decay and for decay modes with $\psi'$ in the final state. The prediction $B(\Lambda_b \to J/\psi\Lambda)=1.6 \times 10^{-4}$ for $|V_{cb}|=0.038$ is consistent with the recent CDF measurement. We also present estimates for $\Omega_c \to (3/2)^++P(V)$ decays and compare with various model calculations.Comment: 24 pages, to appear in Phys. Rev. Uncertainties with form factor q^2 dependence are discusse

Characterization of soil heavy metal pools in paddy fields in Taiwan: chemical extraction and solid-solution partitioning

Ongoing industrialization has resulted in an accumulation of metals like Cd, Cu, Cr, Ni, Zn, and Pb in paddy fields across Southeast Asia. Risks of metals in soils depend on soil properties and the availability of metals in soil. At present, however, limited information is available on how to measure or predict the directly available fraction of metals in paddy soils. Here, the distribution of Cd, Cu, Cr, Ni, Zn, and Pb in 19 paddy fields among the total, reactive, and directly available pools was measured using recently developed concepts for aerated soils. Solid-solution partitioning models have been derived to predict the directly available metal pool. Such models are proven to be useful for risk assessment and to derive soil quality standards for aerated soils. Soil samples (0-25 cm) were taken from 19 paddy fields from five different communities in Taiwan in 2005 and 2006. Each field was subdivided into 60 to 108 plots resulting in a database of approximately 3,200 individual soil samples. Total (Aqua Regia (AR)), reactive (0.43 M HNO3, 0.1 M HCl, and 0.05 M EDTA), and directly available metal pools (0.01 M CaCl2) were determined. Solid-solution partitioning models were derived by multiple linear regressions using an extended Freundlich equation using the reactive metal pool, pH, and the cation exchange capacity (CEC). The influence of Zn on metal partitioning and differences between both sampling events (May/November) were evaluated. Total metals contents range from background levels to levels in excess of current soil quality standards for arable land. Between 3% (Cr) and 30% (Cd) of all samples exceed present soil quality standards based on extraction with AR. Total metal levels decreased with an increasing distance from the irrigation water inlet. The reactive metal pool relative to the total metal content is increased in the order C

de Sitter geodesics: reappraising the notion of motion

The de Sitter spacetime is transitive under a combination of translations and proper conformal transformations. Its usual family of geodesics, however, does not take into account this property. As a consequence, there are points in de Sitter spacetime which cannot be joined to each other by any one of these geodesics. By taking into account the appropriate transitivity properties in the variational principle, a new family of maximizing trajectories is obtained, whose members are able to connect any two points of the de Sitter spacetime. These geodesics introduce a new notion of motion, given by a combination of translations and proper conformal transformations, which may possibly become important at very-high energies, where conformal symmetry plays a significant role.Comment: 9 pages. V2: Presentation changes aiming at clarifying the text; version accepted for publication in Gen. Rel. Gra

Hamiltonian Formalism of the de-Sitter Invariant Special Relativity

Lagrangian of the Einstein's special relativity with universal parameter $c$ ($\mathcal{SR}_c$) is invariant under Poincar\'e transformation which preserves Lorentz metric $\eta_{\mu\nu}$. The $\mathcal{SR}_c$ has been extended to be one which is invariant under de Sitter transformation that preserves so called Beltrami metric $B_{\mu\nu}$. There are two universal parameters $c$ and $R$ in this Special Relativity (denote it as $\mathcal{SR}_{cR}$). The Lagrangian-Hamiltonian formulism of $\mathcal{SR}_{cR}$ is formulated in this paper. The canonic energy, canonic momenta, and 10 Noether charges corresponding to the space-time's de Sitter symmetry are derived. The canonical quantization of the mechanics for $\mathcal{SR}_{cR}$-free particle is performed. The physics related to it is discussed.Comment: 24 pages, no figur

Charmless Exclusive Baryonic B Decays

We present a systematical study of two-body and three-body charmless baryonic B decays. Branching ratios for two-body modes are in general very small, typically less than $10^{-6}$, except that \B(B^-\to p \bar\Delta^{--})\sim 1\times 10^{-6}. In general, $\bar B\to N\bar\Delta>\bar B\to N\bar N$ due to the large coupling constant for $\Sigma_b\to B\Delta$. For three-body modes we focus on octet baryon final states. The leading three-dominated modes are $\bar B^0\to p\bar n\pi^-(\rho^-), n\bar p\pi^+(\rho^+)$ with a branching ratio of order $3\times 10^{-6}$ for $\bar B^0\to p\bar n\pi^-$ and $8\times 10^{-6}$ for $\bar B^0\to p\bar n\rho^-$. The penguin-dominated decays with strangeness in the meson, e.g., $B^-\to p\bar p K^{-(*)}$ and $\bar B^0\to p\bar n K^{-(*)}, n\bar n \bar K^{0(*)}$, have appreciable rates and the $N\bar N$ mass spectrum peaks at low mass. The penguin-dominated modes containing a strange baryon, e.g., $\bar B^0\to \Sigma^0\bar p\pi^+, \Sigma^-\bar n\pi^+$, have branching ratios of order $(1\sim 4)\times 10^{-6}$. In contrast, the decay rate of $\bar B^0\to\Lambda\bar p\pi^+$ is smaller. We explain why some of charmless three-body final states in which baryon-antibaryon pair production is accompanied by a meson have a larger rate than their two-body counterparts: either the pole diagrams for the former have an anti-triplet bottom baryon intermediate state, which has a large coupling to the $B$ meson and the nucleon, or they are dominated by the factorizable external $W$-emission process.Comment: 46 pages and 3 figures, to appear in Phys. Rev. D. Major changes are: (i) Calculations of two-body baryonic B decays involving a Delta resonance are modified, and (ii) Penguin-dominated modes B-> Sigma+N(bar)+p are discusse

Characteristics and Sensing Properties of the La1-xNdxCo0.3Fe0.7O3 System for CO Gas Sensors

A series of nanostructured La1-xNdxCo0.3Fe0.7O3 perovskite-type (x ranging from 0 to 1) were prepared using the co-precipitation method. CO gas sensing properties of La1-xNdxCo0.3Fe0.7O3 sensors were performed. La0.7Nd0.3Co0.3Fe0.7O3 sensor showed the highest response at 250 °C (S=52.8)

Applicability of perturbative QCD to Λb→Λc\Lambda_b \to \Lambda_c decays

We develop perturbative QCD factorization theorem for the semileptonic heavy baryon decay $\Lambda_b \to \Lambda_c l\bar{\nu}$, whose form factors are expressed as the convolutions of hard $b$ quark decay amplitudes with universal $\Lambda_b$ and $\Lambda_c$ baryon wave functions. Large logarithmic corrections are organized to all orders by the Sudakov resummation, which renders perturbative expansions more reliable. It is observed that perturbative QCD is applicable to $\Lambda_b \to \Lambda_c$ decays for velocity transfer greater than 1.2. Under requirement of heavy quark symmetry, we predict the branching ratio $B(\Lambda_b \to \Lambda_c l{\bar\nu})\sim 2$, and determine the $\Lambda_b$ and $\Lambda_c$ baryon wave functions.Comment: 12 pages in Latex file, 3 figures in postscript files, some results are changed, but the conclusion is the sam

First Report of Alternaria Black Spot Disease Caused by Alternaria alternata on the Invasive Weed Solanum rostratum in Xinjiang, China

Solanum rostratum is a noxious weed, native to Mexico and the USA, which has invaded Liaoning, Jilin, Hebei, Inner Mongolia, Shanxi, Xinjiang and Beijing, China (Eminniya et al., 2013). In August 2015, foliar symptoms of yellowish to black spots were observed on plants of S. rostratum nearby an agricultural plantation in Changji, Xinjiang. The following year, about 17% of the 206 plants surveyed on about 0.2 ha of deserted farmland were infected from July-September (at 19-35°C under 29-97% RH)

1/m_Q Corrections to the Bethe-Salpeter Equation for \Lambda_{Q} in the Diquark Picture

Corrections of order 1/m_Q (Q=b or c) to the Bethe-Salpeter (B-S) equation for \Lambda_Q are analyzed on the assumption that the heavy baryon \Lambda_Q is composed of a heavy quark and a scalar, light diquark. It is found that in addition to the one B-S scalar function in the limit m_Q -> \infty, two more scalar functions are needed at the order 1/m_Q. These can be related to the B-S scalar function in the leading order. The six form factors for the weak transition \Lambda_b -> \Lambda_c are expressed in terms of these wave functions and the results are consistent with heavy quark effective theory to order 1/m_Q. Assuming the kernel for the B-S equation in the limit m_Q -> \infty to consist of a scalar confinement term and a one-gluon-exchange term we obtain numerical solutions for the B-S wave functions, and hence for the $\Lambda_b \to \Lambda_c$ form factors to order 1/m_Q. Predictions are given for the differential and total decay widths for \Lambda_b -> \Lambda_c l \bar{\nu}, and also for the nonleptonic decay widths for \Lambda_b -> \Lambda_c plus a pseudoscalar or vector meson, with QCD corrections being also included.Comment: Latex, 24 pages, two figure