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Previous studies have shown that ghrelin, a peptide produced in the stomach, attenuates acute lung injury (ALI) in various animal models, and that some of these effects are associated with inhibition of the nuclear factor κB signaling pathway. This study investigated whether ghrelin exerts beneficial effects on hemorrhagic shock (HS)-induced ALI by modulating nuclear factor κB inhibitor kinase/nuclear factor κB inhibitor/nuclear factor κB (IKK/IκBα/NF-κB) pathway activity. HS was induced in male SD rats by withdrawing blood to a mean arterial pressure (MAP) of 40 mm Hg for 1 h; rats then received ghrelin (10 nmol/kg) or vehicle intravenously and were resuscitated with the shed blood and an equal volume of Ringer lactate solution followed by observation for 2 h. After resuscitation, samples were collected and analyzed for lung histopathology, wet to dry weight ratio (W/D), bronchoalveolar lavage fluid (BALF) protein, neutrophil infiltration, plasma inflammatory cytokines (TNF-α and IL-6), and cytoplasmic phosphorylated IKKβ, IκBα, phosphorylated IκBα and nuclear NF-κB expression. Compared to those in the two sham groups, lung injury, W/D, BALF protein, neutrophil infiltration, plasma TNF-α and IL-6 levels, and IKK/IκBα/NF-κB pathway activation were significantly increased in HS rats. After ghrelin administration, all parameters analyzed were decreased compared to those without ghrelin in HS rats. Moreover, ghrelin alleviated the decreased MAP after resuscitation compared to that in HS rats. Exogenous ghrelin attenuates the inflammatory response and acute lung injury after HS. These beneficial effects appear to be mediated through inhibition of IKK/IκBα/NF-κB signaling.

RANSAC is a popular robust model estimation algorithm in various computer vision applications. However, the speed of RANSAC declines dramatically as the inlier rate of the measurements decreases. In this paper, a novel Adaptively Ranked Sample Consensus(ARSAC) algorithm is presented to boost the speed and robustness of RANSAC. The algorithm adopts non-uniform sampling based on the ranked measurements to speed up the sampling process. Instead of a fixed measurement ranking, we design an adaptive scheme which updates the ranking of the measurements, to incorporate high quality measurements into sample at high priority. At the same time, a geometric constraint is proposed during sampling process to select measurements with scattered distribution in images, which could alleviate degenerate cases in epipolar geometry estimation. Experiments on both synthetic and real-world data demonstrate the superiority in efficiency and robustness of the proposed algorithm compared to the state-of-the-art methods.

Obtaining a high dynamic range (HDR) image from multiple low dynamic range images with different exposures is an important step in various computer vision tasks. One of the ongoing challenges in the field is to generate HDR images without ghosting artifacts. Motivated by an observation that such artifacts are particularly noticeable in the gradient domain, in this paper, we propose an HDR imaging approach that aggregates the information from multiple LDR images with guidance from image gradient domain. The proposed method generates artifact-free images by integrating the image gradient information and the image context information in the pixel domain. The context information in a large area helps to reconstruct the contents contaminated by saturation and misalignments. Specifically, an additional gradient stream and the supervision in the gradient domain are applied to incorporate the gradient information in HDR imaging. To use the context information captured from a large area while preserving spatial resolution, we adopt dilated convolutions to extract multi-scale features with rich context information. Moreover, we build a new dataset containing 40 groups of real-world images from diverse scenes with ground truth to validate the proposed model. The samples in the proposed dataset include more challenging moving objects inducing misalignments. Extensive experimental results demonstrate that our proposed model outperforms previous methods on different datasets in terms of both quantitative measure and visual perception quality.

The widespread existence of potentially toxic heavy elements have become one of the serious environmental concerns around the globe. Thus, it is highly important to develop efficient and selective chemical sensors to detect such potentially toxic elements. Herein, we developed a rhodamine-2-amino-5-bromopyrimidine based chemosensor (RBP) for the selective detection of toxic elements using Hg2+ and Cr3+ as model elements in combination with other competitive ions such as Al3+, Ag+, Ca2+, Ba2+, Cd2+, Fe2+, Fe3+, Li+, K+, Mn2+, Mg2+, Cu2+, Na+, Ni2+, Pb2+and Zn2+. The newly developed RBP displayed good visibility, high sensitivity, excellent selectivity, high binding ability and low limit of detection in CH3CN/HEPES buffer (1 mM 3:2 v/v, pH 7.3) as a medium. The binding constants of RBP for Hg2+ and Cr3+ were 1.09 × 107 M−1 and 8.3 × 104 M−1, respectively. As compared to earlier reported studies, the lowest detection limits (LOD), i.e., 1.6 μM for Hg2+ and 4.9 μM for Cr3+ were recorded. RBP also show reversible binding affinity with Hg2+ and Cr3+ in the presence of ethylenediaminetetraacetate (EDTA). The binding mode between metal ions and RBP were further investigated by using density functional theory (DFT) calculations, which support the experimental findings very well. More importantly, RBP can be prepared as a test paper kit to detect the concentration of Hg2+ and Cr3+ ions by changing the color of the paper visible to naked eyes and is potential for the practical infield application. In addition, the results obtained from confocal microscopy revealed that the probe is cell permeable with low cytotoxicity and can be employed as a bio-imaging reagent for intracellular recognition of Hg2+ and Cr3+ ratification in human breast cancer cells MCF-7.

Blind image deblurring aims to recover the sharp image from a blurred observation, which is an ill-posed inverse problem. Proper image priors for the unknown variables (i.e. latent sharp image and blur kernel) are crucial. Abundant previous methods have shown the effectiveness of the sparsity-based priors on both image gradients and the blur kernel. The correlation among the elements of the sparse variables is paid less attention, however. In this paper, we propose to handle the blind image deblurring problem by promoting group sparsity. The proposed group sparsity priors are based on the fact that the nonzero elements of natural image gradients and blur kernels tend to cluster in structured group pattern. Based on the proposed priors, we introduce proper algorithms to iteratively update latent image gradients and blur kernel, respectively. The proposed algorithms preserve the salient structures and smooth the minor components in image gradients and restrict the blur kernel in a domain of dynamic group sparse vector. To illustrate the reliability of the proposed algorithm, we conduct experiments to analyze the properties of the regularizers and the convergence property of the proposed algorithm. Experiments with both quantitative and visual comparison further prove the effectiveness of the proposed method.

Tetra-amido macrocyclic ligand (TAML) activator is a functional analog of peroxidase enzymes, which activates hydrogen peroxide (H2O2) to form high valence iron-oxo complexes that selectively degrade persistent aromatic organic contaminants (ACs) in water. Here, we develop quantitative structure–activity relationship (QSAR) models based on measured pseudo first-order kinetic rate coefficients ( k obs ) of 29 ACs (e.g., phenols and pharmaceuticals) oxidized by TAML/H2O2 at neutral and basic pH values to gain mechanistic insight on the selectivity and pH dependence of TAML/H2O2 systems. These QSAR models infer that electron donating ability ( E HOMO ) is the most important AC characteristic for TAML/H2O2 oxidation, pointing to a rate-limiting single-electron transfer (SET) mechanism. Oxidation rates at pH 7 also depend on AC reactive indices such as f m i n − and qH+, which respectively represent propensity for electrophilic attack and the most positive net atomic charge on hydrogen atoms. At pH 10, TAML/H2O2 is more reactive towards ACs with a lower hydrogen to carbon atoms ratio (#H:C), suggesting the significance of hydrogen atom abstraction. In addition, ln k obs of 14 monosubstituted phenols is negatively correlated with Hammett constants (σ) and exhibits similar sensitivity to substituent effects as horseradish peroxidase. Although accurately predicting degradation rates of specific ACs in complex wastewater matrices could be difficult, these QSAR models are statistically robust and help predict both relative degradability and reaction mechanism for TAML/H2O2-based treatment processes.

Herein, we report a new rhodamine-based multianalyte (Cu2+ and Hg2+) fluorescent sensor RH-FP. The synthesized probe acts as a dual chemosensor for recognition of Cu2+ and Hg2+ in acetonitrile-water (4:1 v/v, pH 7.2 with 10 mM, HEPES) in the presence of other miscellaneous metal cations i.e. Ag+, Al3+, Ba2+, Ca2+, Cd2+, Fe3+, Fe2+, K+, Li+, Mg2+, Mn2+, Cu+2, Pb2+, Ni2+, Na+ and Zn2+. A highly selective and sensitive colorimetric (colorless to pink) response accompanied by a significant increase in absorption and emission maxima (250-folds) was observed by the interaction of RH-FP and Cu2+ or Hg2+. This makes RH-FP a suitable “bare-eye” detector. The Job’s plot and ESI–MS confirm 1:1 binding stoichiometry between sensor RH-FP and metal cations. The calculated binding constant for the complexes (RH-FP-Cu2+ and RH-FP-Hg2+) are 3.37 × 105 mol−1 and 7.6 × 105 mol−1, with a detection limit of 3.9 nm and 2.36 nm respectively. The binding mechanism was confirmed by Fourier transform infra-red spectroscopy (FT-IR) 1H, 13C NMR and density functional theory (DFT) calculations. Moreover, the fluorescent sensor RH-FP displayed potential in-field applications as detection kit and in fluorescent imaging of biological systems to detect Cu2+ or Hg2+.

Current image editing algorithms prevailingly involve specific processing intensities. After the network training phase, the definite mapping is carried on testing images, which leads to under- or over-editing in certain cases. However, for many real problems, having access to diverse intensities of processing of the output is preferable. The hypothesis is that the part of parameters that correspond to the intensity of processing of the network are implicitly embedded in the whole parameter set and can be explicitly extracted and utilized, even with limited supervision. In this paper, we introduce the concept of Intensity of Processing, termed as IP, and propose image editing with Varying Intensities of Processing, termed as VIP. Given the input and corresponding fully-edited output, we would like to not only figure out the particular mapping from input to output, but also be able to obtain multiple continuous intermediate states with in-between intensities of processing. Refer to the network that deals with the original image editing operation as Base Network. By adding an extra module, which we call Condition Encoder, to condition and regulate the Base Network, we make the whole image editing process controllable. Moreover, we develop a triplet loss and construct the sequentiality of generated intermediate states with limited supervision. A significant advantage of our method is that it does not require groundtruth images of the middle states during training, which substantially relaxes the range of applicable problems. Extensive experiments demonstrate the effectiveness and potentiality of the proposed framework; discussion and future work are also provided.

Weakly-supervised semantic segmentation, as a promising solution to alleviate the burden of collecting per-pixel annotations, aims to train a segmentation model from partial weak annotations. Scribble on the object is one of the commonly used weak annotations and has shown to be sufficient for learning a decent segmentation model. Despite being effective, scribble-based weakly-supervised learning methods often lead to imprecise segmentation on object boundaries. This is mainly because the scribble annotations usually locate inside the objects and the dataset lacks annotations close to the semantic boundaries. To alleviate this issue, this paper proposes a simple-but-effective solution, i.e., BoundaryMix, which generates pseudo training image-annotation pairs from the original images to supplement the missing semantic boundaries. Specifically, given a prediction of segmentation, we cut off the regions around the estimated boundaries, which are error-prone and replace them with the contents from another image, which in effect creates new samples with less ambiguity around semantic boundaries. With training on scribbles and the on-the-fly generated pseudo annotations, the network acquires better prediction capability around the boundary region and thus improves the overall segmentation performance. By conducting experiments on PASCAL VOC 2012 dataset and POTSDAM dataset with only scribble annotations, we demonstrate the excellent performance of the proposed method and the almost closed gap between scribble-supervised and fully-supervised image segmentation.

The structural polymorphism of the oxygen-evolving complex is of great significance to photosynthetic water oxidation. Employing density functional theory calculations, we have made further advisement on the interconversion mechanism of O5 transfer in the S2 state, mainly focusing on the potentiality of multi-state reactivity and spin transitions. Then, O5 protonation is proven impossible in S2 for irreversibility of the interconversion, which serves as an auxiliary judgment for the protonation state of O5 in S1. Besides, the structural polymorphism could also be archived by alternative mechanisms involving Mn3 ligand exchange, one of which with Mn3(III) makes sense to substrate water exchange in S2, although being irresponsible for the derivations of the observed EPR signals. During the water exchange, high-spin states would prevail to facilitate electron transfer between the ferromagnetically coupled Mn centers. In addition, water exchange in S1 could account for the closed-cubane structure as the initial form entering S2 at cryogenic temperatures. With regard to water oxidation, the structural flexibility and variability in both S2 and S3 guarantee smooth W2-O5 coupling in S4, according to the substrate assignments from water exchange kinetics. Within this theoretical framework, the new XFEL findings on S1-S3 can be readily rationalized. Finally, an alternative mechanistic scenario for O O bond formation with ·OH radical near O4 is presented, followed by water binding to the pivot Mn4(III) from O4 side during S4-S0. This may diversify the substrate sources combined with the Ca channel in water delivery for the forthcoming S-cycle.

ABEEM σπ polarizable force field (PFF) with fluctuating charges works well for searching stable conformations of Val-dipeptide and Val-tripeptide, showing importance of the polarization. The results demonstrate that ABEEM σπ PFF is able to search out all the 6 types of stable conformations of Val-dipeptide and 34 types of stable conformations of Val-tripeptide that are just all exactly found by the calculations of ab initio B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) methods. In contrast, the force fields with the fixed-charges (FC), such as ABEEM σπ -FC, AMBER-FC 99sb and OPLS/AA-FC force fields can only search out less or much less numbers of stable conformations for them.

A new discrete isospectral problem and the corresponding hierarchy of nonlinear differential-difference equations are proposed. On the basis of the theory of algebraic curves, the continuous flow and discrete flow related to the hierarchy of differential-difference equations are straightened out using the Abel-Jacobi coordinates. The meromorphic function and the Baker-Akhiezer function are introduced on the hyperelliptic curve. Quasi-periodic solutions of the corresponding hierarchy of differential-difference equations are constructed with the help of the asymptotic properties and the algebro-geometric characters of the meromorphic function, the Baker-Akhiezer function and the hyperelliptic curve.

The electrochemical properties of porous composite cathode consisting of Sm0.5Sr0.5CoO3 (SSC) and 8 mol% Y2O3 doped zirconia (YSZ) have been investigated in Ni/YSZ anode-supported single cells at 600 � C under oxygen with/without ozone conditions. The Microscopic features and X-ray powder diffraction patterns of the cathode don’t show obvious change before and after the measurement. However, the power density of the cell increases in ozone-contained ambient, which is approximately 140% higher than that in ozone-free ambient in most. The effect of the ozone on the performance of cathode is also examined by impedance spectra and Raman spectra. The results of the impedance spectra indicate that polarization resistance decreases in the ozone-contained ambient compared with that in ozone-free ambient. And the Raman spectra suggest that the physicochemical properties of SSC/YSZ porous cathode are also modified. 2014 Published by Elsevier B.V.

The integrity of the genetic information is constantly threatened by oxidizing agents. Oxidized guanines have all been linked to different types of cancers. Theoretical approaches supplement the assorted experimental techniques, and bring new sight and opportunities to investigate the underlying microscopic mechanics. Unfortunately, there is no specific force field to DNA system including oxidized guanines. Taking high level ab initio calculations as benchmark, we developed the ABEEMσπ fluctuating charge force field, which uses multiple fluctuating charges per atom. And it was applied to study the energies, structures and mutations of base pairs containing oxidized guanines. The geometries were obtained in reference to other studies or using B3LYP/6-31+G* level optimization, which is more rational and timesaving among 24 quantum mechanical methods selected and tested by this work. The energies were determined at MP2/aug-cc-pVDZ level with BSSE corrections. Results show that the constructed potential function can accurately simulate the change of H-bond and the buckled angle formed by two base planes induced by oxidized guanine, and it provides reliable information of hydrogen bonding, stacking interaction and the mutation processes. The performance of ABEEMσπ polarizable force field in predicting the bond lengths, bond angles, dipole moments etc. is generally better than those of the common force fields. And the accuracy of ABEEMσπ PFF is close to that of the MP2 method. This shows that ABEEMσπ model is a reliable choice for further research of dynamics behavior of DNA fragment including oxidized guanine.

The contamination of food with Aspergillus flavus and subsequent aflatoxins is considered as one of the most severe safety problems in the world. The application of microorganisms and the produced bio-active compounds is considered as the most promising method for controlling foodborne pathogens and mycotoxins contamination both in pre- and post-harvest. Vt-7, identified as Enterobacter asburiae, was able to completely inhibit the growth of Aspergillus flavus (AF) and other seven important fungal pathogens by the production of volatiles. Additionally, it can also significantly inhibited AF infection on peanuts in storage, down-regulated the gene expression of aflatoxin biosynthesis and eventually prevented aflatoxins production. Scanning electron microscope further proved that Vt-7 volatiles prevented conidia germination of AF on peanut surface, and severely destroyed the conidia structure. Gas chromatography – tandem mass spectrometry revealed that two abundant compounds (1-Pentanol and Phenylethyl Alcohol) were involved in the volatile profiles. They showed great antagonistic activity against AF with minimal inhibitory concentration at 200 μL/L. Therefore, E. asburiae Vt-7, and volatiles 1-Pentanol and Phenylethyl Alcohol were effective agents in controlling AF and aflatoxins in peanut during storage. They will provide novel strategies for the application of microbe and bio-active compounds against fungal pathogens and mycotoxins in food and grains during storage.

The effect of temperature on the adsorption of sulfanilamide (SA) onto aluminum oxide was researched through batch adsorption experiments, and was then simulated using the molecular dynamics (MD) method. The results show that SA can be adsorbed effectively by the adsorbent of aluminum oxide due to their interactions between SA molecule and the surface of aluminum oxide crystal, and temperature is a key factor which influences the adsorption efficiency obviously. The removal ratio of SA at 298 K is the highest among the selected temperatures (293 K, 298 K, 303 K). MD simulations revealed the interactions between SA molecules and (0 1 2) surface of aluminum oxide crystal at molecular level. The SA molecule has clung to the (0 1 2) face of aluminum oxide crystal, and its structure is deformed during its combining process with the surface. Both binding energies (Eb) and deformation energies (ΔEdeform) in the SA-aluminum oxide system follow the same order as: SA-Al2O3 (298 K) > SA-Al2O3 (293 K) > SA-Al2O3 (303 K). Their deformation energies are far less than their non-bonding energies. Analysis of radial distribution functions (RDFs) indicates that SA can be adsorbed effectively by aluminum oxide crystal mainly through non-bond interactions. The simulation results agree well with the experimental results, which verify the rationality and reliability of the MD simulation. The further MD simulations provide theoretically optimal temperature (301 K) for the adsorption of SA onto aluminum oxide. The molecular dynamics simulation will be useful for better understanding the adsorption mechanism of antibiotics onto metal oxides, which will also be helpful for optimizing experimental conditions to improve the adsorptive removal efficiency of antibiotics.

A large-area zinc oxide (ZnO) nanorod bundle array was grown on a silicon nanoporous pillar array (Si-NPA) substrate by a chemical vapor deposition method, and its field-emission properties was studied. The structural characterization disclosed that the bundles were composed of hexagonal ZnO nanorods growing along c -axis and taking roots into the silicon pillars of Si-NPA. The average diameter and length of the ZnO nanorods were ∼145 nm and ∼10 μm, respectively. The field-emission measurements showed that the turn-on field of ZnO/Si-NPA was 4.6 V/μm with an emission current density (ECD) of 1 μA/cm 2 , and an ECD of 420 μA/cm 2 was achieved at an applied field of 8.89 V/μm. The field enhancement factor was calculated to be ∼1700 based on the Fowler–Nordheim theory. According to the obtained charge coupled device (CCD) image, the density and brightness of the emission dots increased with the applied field, and the high emission dot density was attributed to the formation of a large number of ZnO nanorod emitting tips. Our results indicated that ZnO/Si-NPA might be a promising electron emission source.

The biological functions of DNA are related to its conformation. In this work, potential energy profiles of nucleic acid torsions associated with the sugar-phosphate backbone and the glycosyl linkage were studied using the ab initio and ABEEMσπ/MM methods. The ABEEMσπ/MM well reproduced the entire potential energy profiles (not just minima) of the torsion of model compounds. The ABEEMσπ/MM method also gives reasonable results about the structures and dipole moments of DNA bases and interactions between bases and one water molecule. The torsions of four deoxyribonucleosides were investigated in aqueous solution through molecular dynamics simulations based on the ABEEMσπ/MM. Reasonable distributions of the torsional angles were observed with the pseudorotation angles in south, glycosyl torsion χ in anti conformation, and g + conformations for torsion γ . The reasonable results on simulating DNA fragments in gas and aqueous solution suggest that the newly constructed ABEEMσπ/MM method would be robust for simulating nucleic acids.

Summary Background After a massive syphilis epidemic in the first half of the 20th century, China was able to eliminate this infection for 20 years (1960–80). However, substantial changes in Chinese society have been followed by a resurgent epidemic of sexually transmitted diseases. Sporadic reports have provided clues to the magnitude of the spread of syphilis, but a national surveillance effort is needed to provide data for planning and intervention. Methods We collected and assessed case report data from China's national sexually transmitted disease surveillance system and sentinel site network. Findings In 1993, the reported total rate of cases of syphilis in China was 0·2 cases per 100 000, whereas primary and secondary syphilis alone represented 5·7 cases per 100 000 persons in 2005. The rate of congenital syphilis increased greatly with an average yearly rise of 71·9%, from 0·01 cases per 100 000 livebirths in 1991 to 19·68 cases per 100 000 livebirths in 2005. Interpretation The results suggest that a range of unique biological and social forces are driving the spread of syphilis in China. A national campaign for detection and treatment of syphilis, and a credible prevention strategy, are urgently needed.

A new representation of the molecular intrinsic characteristic contour (MICC) is carried out by using an ab initio method for some small organic molecules, such as methane, ethane, ethylene, acetylene and formaldehyde. The detailed comparison of the MICCs for these molecules with the respective isolated atomic characteristic boundary radii have been done for giving direct information about the spatial change in forming the molecules from individual atoms. These knowledge and related pictures of the potential acting on an electron within a molecule may be useful in discussing the molecular properties and chemical bonding.

The geometries of the axially bromo-substituted boron subphthalocyanine (SubPc–Br, 1), and its peripherally nitro-substituted derivatives (SubPc–Br(NO2)x, x=1,2,3; 2–4) and non-peripheral derivative SubPc–BrNO2 (2a) have been optimized using the ab initio and density functional theories at the HF/3-21G and B3LYP/3-21G levels. Normal mode vibrational analyses have been performed for 1, 2 and 2a, and their standard thermodynamic functions have been calculated. The geometrical optimization has also been made at the B3LYP/6-31G∗ level for 1, 2 and 2a, and vibrational analysis has been performed for 1. It was found that the geometries, electronic structures and frequencies obtained at the B3LYP level of theory with the 3-21G and 6-31G∗ basis sets are similar, but those obtained at the HF and B3LYP levels with the same basis set are rather different. This indicates that the electron correlation plays an important role in these SubPcs. All SubPcs have bowl-like structures, and NO2 substitution has only a small influence on the geometry and electronic structure of the SubPc framework. The corresponding geometrical parameters in various isomers are very close. Compounds 1, 2, 2a, and 3 have large dipole moments, but 4 is nearly non-polar. Non-peripheral derivative 2a is less stable than the peripheral derivative 2 by more than 20 kJ mol−1.

The ridge and furrow rainfall harvesting (RFRH) system with mulches is being promoted to increase water availability for crops for higher and stable agricultural production in many areas of the Loess Plateau in northwest China. In the system, plastic-covered ridges serve as rainfall-harvesting zones and stone-, straw- or film-mulched furrows serve as planting zones. To adopt this system more effectively, a field study (using corn as an indicator crop) was conducted to determine the effects of different ridge:furrow ratios and supplemental irrigation on crop yield and water use efficiency (WUE) in the RFRH system with mulches during the growing seasons of 1998 and 1999. The results indicated that the ridge:furrow ratios had a significant effect on crop yield and yield components. The 120:60 cm ridge and furrow (120 cm wide ridge and 60 cm wide furrow) system increased yield by 27.9%, seed weight per head by 14.8%, seed number per head by 7.4% and 1000-seed weight by 4.7%, compared with the 60:60 cm ridge and furrow (60 cm wide ridge and 60 cm wide furrow) system. No differences in WUE were found between the two ratio systems. For corn and winter wheat, the optimum ridge:furrow ratio seems to be 1:1 in the 300-mm rainfall area, 1:2 in the 400-mm rainfall area and 1:4 in the 500-mm rainfall area. The optimum ridge:furrow ratio seems to be 1:3 for millet in the 300-mm rainfall area, although it is unnecessary to adopt RFRH practice in regions with more than 400 mm rainfall. The most effective ridge size for crop production seems 60 cm in the Loess Plateau. Implementing supplemental irrigation in the RFRH system is also a useful way to deal with the temporal problem of moisture deficits. In the case of corn, supplemental irrigation at its critical growth stage can increase both grain yield and WUE by 20%. The combination of in situ RFRH system with supplemental irrigation practice will make the RFRH system more attractive.

Low cost microcatchment treatments for rainwater harvesting are needed under the local poor economic conditions in the semiarid loess regions of northwest China. This paper was intended to study the effectiveness of runoff yield from compacted catchments with some local earth materials under the natural rainfall. The compacted catchments were constructed with uniformly mixed loess, laterite and fine sand at the ratio of 1:1:1. The results showed that rainfall–runoff efficiency from such compacted plots was 33% of the total rainfall as compared to 8.7% from the untreated plots. The compacted catchments had low infiltration rate, and the minimum precipitation required to produce runoff (threshold rainfall) was 4 mm under no antecedent rainfall effects and 1.9 mm under antecedent rainfall effects. In contrast, the threshold rainfall was about 8.5 mm for the untreated catchments under no antecedent rainfall effects and 6 mm under antecedent rainfall effects. The compacted catchment with local soils has a great potential for rainfall harvesting in the semiarid regions of China, but soil erosion is a problem, some form of soil stabilization would be needed in future use.

The molecular structures, vibrational spectra, standard thermodynamic functions and heats of formation of methyl nitrate, ethyl nitrate, propyl nitrate, isopropyl nitrate, butyl nitrate, ethylene glycol dinitrate and nitroglycerin have been calculated at the levels of HF, MP2 and B3LYP theories in conjuction with the 6-31G* basis set. The molecular geometries and scaled frequencies calculated at the MP2 and B3LYP levels are comparable to the available experimental results in gas phase, and furthermore, the B3LYP results are slightly better than the MP2 results. The standard thermodynamic functions of NEs increase while the total energies decrease at constants with increasing number of carbon atoms and ONO 2 groups in molecules. The heats of formation obtained from the isodesmic reactions at the B3LYP and HF levels and from the atomization reactions at the B3LYP level are in reasonable agreement with the experimental results. The average absolute deviations are 4.21, 7.72 and 8.47 kJ mol −1 , respectively. But the heats of formation obtained from the atomization reaction at the HF and MP2 levels are much too higher.

A plastic-covered ridge and furrow rainfall harvesting (PRFRH) system combined with mulches was designed to increase water availability to crops for improving and stabilizing agricultural production in the semiarid Loess region of northwest China. The system was built by shaping the soil surface with alternate ridges and furrows along the contour. The plastic-covered ridges served as a rainfall harvesting zone and furrows as a planting zone. Some materials were also used to mulch the furrows to increase the effectiveness of the harvested water. This system can make better utilization of light rain by harvesting rainwater through the plastic-covered ridge. The field experiment (using corn as an indicator crop) showed that grain yields in the PRFRH system with mulches in 1998 and 1999 were significantly higher than the controls, with an increase of 4010–5297 kg per ha (108–143%). In most treatments, the water use efficiencies (WUE) were in excess of 2.0 kg m−3. The WUE values of corn in this system were 1.9 times greater than the controls in 1998 and 1.4 times greater than the controls in 1999. The plastic-covered ridge led to a yield increase of 3430 kg per ha (92%) in 1998 and of 1126 kg per ha (21%) in 1999 compared with the uncovered ridge. On average, the additional mulches in the furrow brought about a yield increase of 8–25%. Based on the results of this study and other researches, this technique can increase corn grain yield by 60–95% in drought and average years, 70–90% in wet years, and 20–30% in very wet years. The PRFRH system had the potential to increase crop yield and produced greater economic benefit, therefore it could be used in regions dominated by light rainfall of low intensity where crops generally fail due to water stress.

In the semiarid region of northwest China, pebble mulches have been used by farmers for over 300 years. However, very little studies were conducted on the effect of pebble mulch on soil erosion by wind. Results of a wind tunnel simulation and a field experiment showed that pebble mulch had two functions in controlling wind erosion: first, it could prevent soil from eroding by wind; second, it could trap dust carried by wind. According to the wind tunnel simulation experiment, pebble mulch reduced wind erosion rate (g m 2 min -1 ) by 84-96% at the different wind velocities (10-26 m s -1 ) in comparison with the controls. In addition, the ratio between total soil loss from the pebble-mulched soil and the bare soil was 0.06. The field study indicated that pebble mulch could trap 1.6-1.8 times more windblown sediments than the control suggesting that pebble mulch might also be effective in controlling dust storms. The grain size distribution of eroded soil showed that a lower percentage of particles in the range of >1.0 mm fractions and a higher percentage in the range of 0.5 and

A field study was conducted to determine the effect of a combination of ridge and furrow method of in-situ rainwater harvesting with gravel mulch on corn production, soil moisture storage, and water-use efficiency in the dry semi-arid region of China. Results showed that plastic-covered ridges had an average runoff efficiency (runoff/rainfall) of 87% as compared to 7% for bare ridges, and could generate runoff at a threshold value of 0·8±0·2 mm rainfall. Bare ridges produced runoff only under high intensity rainfall events, and was ineffective for harvesting rainfall in the study area. The plastic-covered ridge and gravel-mulched furrow method of rainwater harvesting was effective in conserving moisture and increasing yield and water-use efficiency. The grain yield in this treatment was 1·9 times that of the conventional flat soil cultivation (control), and the water-use efficiency was 1·8 times that of the control. The good performance of the film-covered surface ridges and gravel-mulched furrows is attributed to the better utilization of light rains, improvement of infiltration in the root zone, and suppression of evaporation losses.

The conformational analysis has been performed on propyl nitrate by using ab initio and density functional methods. Seven energy minima corresponding to seven different conformers have been found and fully optimized at the B3LYP/6-31G∗ and MP2/6-311G∗ levels. The rotational transition states have been optimized too at the B3LYP/6-31G∗ level. The geometries obtained by the B3LYP agree well with those obtained by the MP2, and both methods predict that the gauche conformer with the ∠CCCO (t3) being twisted by about 63° has the lowest energy and is 1.71 (MP2) and 0.53 (B3LYP) kJ mol−1 more stable than the planar conformer, but the stability order of different conformers obtained by them are somewhat different. The energy differences between various conformers and the barriers to internal rotation are all very low. Torsion around ∠CCON decreases while torsion around t3 increases the stability by about 3.2 and 1.5 kJ/mol, respectively, from MP2 calculations. Vibrational analyses have been performed on the stable conformers at the B3LYP/6-31G∗ level. The standard thermodynamic functions and the equilibrium mole fractions have been derived. The heats of formation of various conformers have been estimated too from the B3LYP total energies and an isodesmic reaction. The calculated thermodynamic properties and heat of formation of propyl nitrate are in reasonable agreement with the experimental results.

The molecular geometries, electronic structures and harmonic vibrational frequencies of methyl nitrate and its substituted derivatives of –F, –Cl, –OH, –CN, –CHO and –CH 3 groups were studied employing ab initio method at the MP2/6-31G* level. The effects of the substituents on the structures and properties were described. It is shown that the C–O and O–N bond lengths and ∠CON angle changes dramatically with the substitution of the various groups, and the energy gaps between LUMO and HOMO decrease. +I inductive effect of substituents makes ONO 2 group more negatively charged and −I effect has an opposite influence. The ν s (NO 2 ) in all the substituted derivatives are a few wave numbers lower than that in methyl nitrate. The shifts of frequencies caused by substitutions are less than 16 cm −1 .