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An optimal dosage of nitrogen has long been known to play important roles in governing nitrogen-use efficiency and improving the yield of plants. However, there is limited information on the isolation and expression profiles of genes related to nitrogen metabolism in peach (Prunus persica L. Batsch). This study isolated five genes involved in nitrogen metabolism and evaluated the effects of a single foliar application of urea on levels of expression of these genes in the leaves of ‘Dazhenbaochiyue’ peach. Cloning resulted in the isolation of 1,767, 1,236, 1,074, 1,758, and 2,721 nt-long cDNAs with full-length open reading frames encoding 588, 411, 357, 585, and 906 amino acids representing the asparagine synthetase (AS), glutamate dehydrogenase (GDH), glutamine synthetase (GS), nitrite reductase (NiR), and nitrate reductase (NR) genes in peach, respectively. An alignment of multiple amino acid sequences revealed that the AS, GDH, GS, and NR proteins in peach shared high levels of sequence conserva...

Iron is required for the Fe-S cluster assembly which occurs in chloroplasts, mitochondria, and cytosol and here we characterized 44 Fe-S cluster biosynthesis genes and investigated their expression profiles during different peach flowering stages. Quantitative real-time PCR analysis shows that the highest expression of most peach Fe-S cluster biosynthesis genes appeared in the full bloom stage. Also, the highest Fe accumulation occurred in the full bloom stage followed by beginning bloom, petal fall, and bud swell stages. Activities of nitrite reductase (NiR) and succinate dehydrogenase (SDH) were closely correlated to the flower Fe content, whereas the aconitase (ACO) activity kept steady during the whole flowering process. Moreover, shading treatment significantly reduced Fe accumulation and NiR, SDH, and ACO activities of the full blooming flowers. Seventeen Fe-S cluster biosynthesis genes were down-regulated in response to a shading treatment. In particular, plastid sulfur mobilization genes were sensitive to the shading treatment.

Copper (Cu2+) ion was determined at micro level by diethyldithiocarbamate (DDTC) spectrophotometry after temperature-dependent solid–liquid separation using N-butyl pyridinium hexafluorophosphate ([BPy]PF6) as a solid solvent and DDTC as an extractant. The results showed that ions can be extracted 100% by DDTC–[BPy]PF6 at pH = 10·20. The extracted species was neutral Cu(DDTC)mCl2 (m = 1) based on slope analysis in the Cu2+–[BPy]PF6–DDTC temperature-dependent solid–liquid separation system. The recovery of Cu2+ extracted into DDTC–[BPy]PF6 can be achieved using 2 mol L−1 HNO3 as stripping agents. Back extraction method was adopted for the detection and quantification of Cu2+ ions using the DDTC spectrometry. The calibration curve was Y = 0·00328 + 0·10279X (correlation coefficient = 0·99922), the linear calibration range was 7·68 × 10−2 0·768 μg mL−1 and the limit of detection was 1·28 × 10−2 μg mL−1 for Cu2+. In this method, the contents of Cu2+ in Tieguanyin tea were determined with relative stan...

Summary Background Peginterferon-α–based therapy frequently leads to neutropenia. It remains unclear whether neutropenia is associated with bacterial infection in chronic hepatitis C (CHC). Aim To evaluate the risk of bacterial infection and neutropenia in patients with CHC treated with peginterferon-α/ribavirin. Methods In all, 207 patients with CHC with (group A, n = 30) and without (group B, n = 177) baseline neutropenia were treated with peginterferon-α/ribavirin. Results Group A had significantly higher rates of moderate (

An attempt on the use of secondary ion mass spectroscopy (SIMS) in studying ancient Chinese bronze is reported with an evaluation of the suitability of SIMS for the provenance study of ancient bronze objects. The advantage of using SIMS in the study of the lead isotope ratio is the high sensitivity that enables the examination of small fragments of valuable relics that are often difficult to collect. The application of SIMS in this direction widens the sampling area, which is limited by the use of thermal ionization mass spectroscopy (TIMS). The focus of the study has been placed on the precision of SIMS when compared to TIMS and the effect of sample matrices on the precision. Samples of Chinese bronze artefacts and a standard lead sample (SRM 981) were tested for their lead isotope ratios using both SIMS and TIMS. A comparison of the data obtained using the two techniques showed that SIMS results have a relatively large standard deviation, which was attributed to the non-uniformity of the ancient samples and the single-isotope detection system of the SIMS set-up used. Matrix effects were found to be small among bronze samples of different compositions. Non-conducting samples can also be analysed when a specimen isolation technique is employed. Although SIMS gave higher uncertainties than TIMS, the SIMS technique can be applied easily to differentiate the high radiogenic lead in Shang bronze artefacts from common lead. Copyright © 2000 John Wiley & Sons, Ltd.

This case–control study aimed to evaluate the diagnostic application of urinary transforming growth factor (TGF) α and serum α-fetoprotein (AFP) in hepatocellular carcinoma (HCC). TGFα and AFP were determined in 90 pairs of age- and gender-matched patients with cirrhotic HCC and patients with cirrhosis alone and 60 healthy controls. The results indicated that TGFα and AFP levels in patients with HCC were higher than in those with cirrhosis alone or healthy controls (each P = 0.0001). Multivariate analysis indicated that TGFα (odds ratio (OR) 1.03, 95 % confidence interval (CI) 1.05–1.16) and AFP (OR 1.03, 95 % CI 1.01–1.06) were closely associated, in a dose-related fashion, with the development of HCC. The optimal cutoff values, determined with the receiver operating characteristic (ROC) curves, were 29 μg/g creatinine for TGFα and 100 ng/ml for AFP, respectively. The areas under ROC curve (AUC) were 0.74 for TGFα and 0.78 for AFP, respectively. Both biomarkers showed the same sensitivity (52.2 %), high specificity, high positive predictive value, and moderate positive likelihood ratio. Determination of both markers in parallel significantly increased the AUC (0.91) and diagnostic accuracy (92.2 %), with a high sensitivity (86.7 %), specificity (97.8 %), positive predictive value (PPV; 97.5 %), and moderate positive likelihood ratio (PLR; 39.4). Among 31 cirrhotic HCC with AFP ≤ 20 ng/ml, the calculated AUC for TGFα was 0.79, with a sensitivity of 64.5 %, specificity of 96.7 %, PPV of 87.0 %, and PLR of 19.5. In conclusion, urinary TGFα and serum AFP are complementary tumor markers for detection of HCC with low AFP production.

This paper addresses the kinetics and related mechanisms of non‐self‐limiting nature of Si reduction of WF6 in cold wall systems for the first time. The growth of such films in low‐pressure chemical‐vapor deposition (LPCVD) and ultrahigh vacuum (UHV) systems is compared. Both systems produce non‐self‐limiting, uniform, controllable, nonporous films. The growth is controlled by process parameters such as the wafer temperature and WF6 concentration at the wafer surface. The order of the Si reduction reaction is 0.5 in the concentration of WF6. The tungsten films deposited in the LPCVD system contaminated with water vapor are thicker than the films grown in the UHV system even when the temperature is below 450 °C. Such thicker films are produced as a result of the formation of an amorphous W‐O layer. From the thermodynamic considerations, the origin of W‐O layer is attributed to a parallel reaction between water vapor, WF6, and substrate Si. The beneficial role played by the W‐O layer is that it prevents any volume shrinkage of the converted layer and restricts lateral encroachment. In the absence of such a layer as in the case of the UHV system, severe volume shrinkage and encroachment are observed. A theoretical model together with physical mechanisms explaining the non‐self‐limiting phenomenon are proposed. The mechanism suggests that a fine‐grained W structure surrounded by a W‐O layer, formed in the LPCVD system, assists faster out‐diffusion of Si through the tungsten films compared to the UHV system. The higher values of the diffusion coefficient for Si out‐diffusion through films grown in the LPCVD system as compared with the UHV system support this mechanism. The out‐diffused Si is substituted to W by reduction reaction to complete the film growth.

The above-ground organs of plants are covered by a cuticle, an extracellular membrane performing important physiological and ecological functions, that consists of the fatty acid-derived polymer cutin and waxes. In the cuticular wax of many species, including the leaves of Prunus laurocerasus, triterpenoids are found at high concentrations. This paper investigates the potential of Raman microspectroscopy for the simultaneous detection of structurally similar triterpenoids in plant cuticles. Relative composition analysis was first performed on artificial triterpenoid mixtures consisting of α-amyrin and oleanolic acid, as well as oleanolic acid and ursolic acid, the two triterpenoids abundantly found in the cuticles of P. laurocerasus. The different triterpenoids could be distinguished in the mixture spectra and the resulting calculated triterpenoid ratios were consistent with the expected values. Qualitative analysis of the Raman spectra of P. laurocerasus cuticle demonstrated the in situ detectability of the triterpenoids using this approach. It is shown here that Raman microspectroscopy has the potential to provide useful information concerning the spatial distribution of some key chemical components of plant cuticles. This technique thus offers a valuable complement to the current standard analytical methods used for analyzing the bulk composition of plant cuticles.

In this communication, we present a study of tip artifacts in atomic force microscope images of nanometer-scale cellular structures created on germanium surfaces by ion bombardment. It is demonstrated that the appearance of a columnar/granular morphology is due to severe image distortion when the tip size is comparable with the mean cell/hole diameter. These tip artifacts can often be deconvoluted by inverting the image and the lateral extension of the cell/hole can be reproduced with reasonable accuracy.

Vanadium pentoxide (V2O5) nanomaterials with various morphologies were prepared by chemical vapour deposition at a relatively low temperature (evaporation temperature of 250 °C and growth temperature of 500 °C) using vanadyl acetylacetonate (VO(acac)2) powder as the vanadium precursor. The obtained samples were characterized by scanning electron microscopy, x-ray diffraction, Raman scattering and photoluminescence spectra. The results revealed that the samples including a V2O5 nanocluster film, V2O5 nanowires and V2O5 nanospheres were synthesized at different distances from the source material. For our chemical vapour transport system, we suggested that VOx vapour and VO(acac)2 vapour existed simultaneously during the growth process, which resulted in different morphologies of V2O5 nanomaterials. The quite different supersaturation distributions of VOx vapour and VO(acac)2 vapour led to three main growth areas. The V2O5 film was grown in the region where the supersaturation of the VOx vapour was high, V2O5 nanowires were obtained where the supersaturation of the VOx vapour was relatively low and V2O5 nanospheres were synthesized in the region where the supersaturation of the VO(acac)2 vapour was high. The growth pressure that influenced the vapour concentration controlled the morphologies of the nanowires. It was found that a specific level of low concentration was necessary to ensure the growth of V2O5 nanowires.

We have measured the energy distributions of electrons field emitted from tungsten carbide, HfC〈100〉, and ZrC〈100〉 tips, and tungsten field emitters with diamondlike carbon coatings. Multiple‐peaked energy distributions were observed from instability induced emission sites on the carbide tips. Energy distributions of electrons field emitted from the diamondlike carbon coated tungsten tips were broader than those from metal tips. They also showed a shift towards lower energies with increases in the emission current.

We have evaluated the cold‐field‐emission characteristics of HfC〈100〉 and ultrasharp tungsten emitters. We found that proper acetylene treatment improved both the angular current confinement and the emission stability of thermally cleaned HfC〈100〉 tips. Stable emission exceeding 10 μA/sr for over 1 h and angular confinement to a 3° semicone angle have been observed. The improvements are probably related to the modified work function and surface chemical composition induced by the acetylene treatment at the tip apex. Carburization of W〈100〉 and W〈111〉 tips also significantly improved the emission current stability. This study indicates the usefulness of surface processing in the development of cold‐field emitters.

Schottky emission tips have been evaluated with microlenses for applications in scanning tunneling microscope aligned field emission microcolumns. Operation of Zr/O/W 〈100〉 Schottky emission tips at 1800 K with an axial separation of 50–100 μm between the tip and a microlens has been successfully tested. The microlens consists of an extraction electrode with a 5‐μm‐diam hole in a 1‐μm‐thick silicon membrane. The preliminary results of this study show that thermal field emission tips can be operated continuously in close proximity to a microlens over a long period of time, and that good emission stability of less than 1% noise fluctuation over 10 h is achieved with emission currents up to at least 100 μA.

An oxygen induced sharpening process of field emitter tips, W〈111〉, for use in a scanning tunneling microscope aligned field emission microcolumn system has been developed. The sharpening process which depends on processing temperature and oxygen pressure can be used to control tip radius accurately with reliability and reproducibility. The measured tungsten removal rate was ∼13 A/min at a processing temperature of ≂1650 K and at an oxygen pressure of ≂4×10−5 Torr. The process is primarily intended for more accurate control of the tip radius and hence performance of newly etched tips, although damaged or blunt tips can also be resharpened in situ with this process. Favorable emission characteristics of the oxygen processed tips have been observed with microcolumn operation: (1) reasonably stable emission current, (2) low extraction voltage, (3) reproducible threefold symmetric emission patterns, and (4) small emission angle.

A three-dimensional close-packed array of Josephson junctions was successfully produced in the form of a bulk granular superconductor. The granular system is a tightly compressed solid of oxide coated small tin particles in the thousand A range. The three-dimensional array of Josephson junctions thus formed showed coherent Josephson oscillations when external rf radiation was imposed, rf induced constant voltage steps were observed on its I-V characteristics at voltages a few thousand times the Josephson voltage hv/2e. The external rf radiation also induced Stable dc voltages on unbiased bulk samples, suggesting a practical mode of microwave detection. The analogy of this bulk superconducting system with a magnetic spin system will be discussed.

Common ion sputtering techniques for depth profiles can cause buildup of charge in low‐conductivity regions such as p‐n junctions in semiconductors, leading to erroneous results. We analyzed Ga0.1Al0.9As liquid phase epitaxial (LPE) layers on GaAs with secondary ion mass spectrometry (SIMS) and observed that the profiles of 69Ga+ and 27Al+ in the low‐conductivity region of these Zn‐diffused LPE layers were a function of the sample bias. We noticed that this artifact was due to the shift and broadening of the secondary ion energy distributions caused by positive charging of the specimen surface. We also found that this could be effectively remedied by integrating the secondary ion yields over a wide energy range. The use of an electron flood gun reduced this charging effect, but complete charge compensation was not achieved even at electron current densities far exceeding the ion current density. This can be explained by the fact that the electron‐induced secondary electron coefficient of GaAlAs is larger ...

The emission of positive atomic secondary ions from single phase binary alloys during 15 keV Ar+ bombardment was studied in an ultrahigh vacuum environment. For all the five alloy systems: Fe–Ni, Cu–Ni, Pd–Ni, Al–Ni, and Si–Ni, the ionization probabilities of the elements show little or no correlation with the bulk alloy density of states or the local density of states near the Fermi level. When the ionization probabilities are compared with the electronegativity differences of the elements, we notice that only the emission of Al+ and Ni+ from Al–Ni alloys seems to follow the direction of the anticipated charge transfer.

The transport of ATP out of mitochondria and uptake of ADP and Pi into the matrix are coupled to the uptake of one proton (Klingenberg, M., and Rottenberg, H. (1977) Eur. J. Biochem. 73, 125--130). According to the chemiosmotic hypothesis of oxidative phosphorylation this coupling of nucleotide and Pi transport to proton transport implies that the P/O ratio for the synthesis and transport of ATP to the external medium is less than the P/O ratio for the synthesis of ATP inside mitochondria. A survey of previous determinations of the P/O ratio of intact mitochondria showed little convincing evidence in support of the currently accepted values of 3 with NADH-linked substrates and 2 with succinate. We have measured P/O ratios in rat liver mitochondria by the ADP pulse method and by 32 Pi esterification, measuring oxygen uptake with an oxygen electrode, and find values close to 2 with beta-hydroxybutyrate as substrate and 1.3 with succinate as substrate in the presence of rotenone to inhibit NADH oxidation. These values were largely independent of pH, temperature, Mg2+ ion concentration, Pi concentration, ADP pulse size, or amount of mitochondria used. We suggest that these are the true values of the P/O ratio for ATP synthesis and transport by mitochondria, and that previously reported higher values resulted from errors in the determination of oxygen uptake and the use of substrates which lead to ATP synthesis by succinate thiokinase.

Measurements have been made within a few micrometers of a current-carrying superconducting-normal boundary, which indicate that an electric potential exists in the superconductor in this region. Near the transition temperature the experimental results are consistent in magnitude and temperature dependence with a theory recently proposed by Rieger, Scalapino, and Mercereau.

Secondary ion mass spectrometry (SIMS), low energy electron diffraction (LEED), and Auger electron spectroscopy (AES) have been employed to study the interactions of silane and phosphine with the Si(100) surface. Phosphine adsorption and desorption were investigated at surface temperatures in the range . At ambient temperature, phosphine saturated the bare Si(100) surface after 3–5L exposure, and fitting adsorption data to a Langmuir model yields the value for the sticking coefficient. Phosphine adsorption was found to follow the pattern of the underlying silicon. Competitive adsorption experiments set an upper bound of for silane adsorption under like conditions. The silicon surface was observed to be passivated with respect to silane adsorption by prior exposure to phosphine, with a layer of preferentially adsorbed phosphine formed which served to preclude subsequent silane adsorption. The results obtained here are discussed in the context of their bearing upon the phosphorus‐doped low pressure chemical vapor deposition process.

Normalized ionization probabilities α+ are reported for binary Fe‐Ni alloys under O+2 bombardment at a 45° incidence angle. It is shown that the dependence of α+ on the composition is much smaller than at normal incidence. Photoemission spectroscopy reveals that both nickel and iron remain essentially metallic under oblique‐incidence bombardment, whereas almost complete oxidation occurs at normal incidence. This is attributed to our observation that sputter yields under oxygen bombardment increase much faster than cos α−1.

Particulate and sulfate emission characteristics of two catalyzed radial-flow wire-mesh particulate traps are presented. The traps were found to be ineffective for particulate reduction. The first trap was dynamometer tested for 25 consecutive EPA Heavy Duty Diesel Transient Cycles and 40 hours of steady-state operation. During steady state testing, particulates were sampled from both the raw and diluted engine exhaust. The total particulate matter was chemically analyzed for sulfate, organic, moisture, and nonextractable fractions. The data indicate significant conversion of fuel sulfur to hygroscopic sulfuric acid. Although solid carbon fraction was reduced, total particulate mass increased. Sulfuric acid condensation presented operational and particulate sampling difficulties. Sampling from the raw exhaust with heated lines showed good sulfur balance between fuel and exhaust contents, but sulfate emission also exceeded the baseline for total particulate matter. Steady-state tests with a second trap with a different catalyst formulation produced similar results and no improvement in total particulate emissions.

The impact of diesel fuel sulfur reduction on directly-emitted and secondary atmospheric particulate is evaluated by experiment and analysis. Experimental evidence shows that fuel sulfur conversion rate to particulate sulfate is linear down to zero sulfur level. Analysis shows that sulfur-derived particulate accounts for the vast majority of atmospheric particulate from diesel engines. Consequently, fuel sulfur reduction would have a far greater impact in reducing atmospheric particulate burden than any other diesel engine particulate control strategy.

Secondary ion emission during sputtering depends very much on the local atomic environments of the sputtered atoms. For example, sputtering with 02 + significantly enhances positive ion formation [1]. This enhancement is attributed to the incorporation of oxygen atoms in the target. The formation of the oxide bonds intensifies the secondary ion yields. In this experiment we moved a step further and tried to see whether the presence of a second metallic component in the sample could influence this oxygen enhancement effect. We also tried to look for any corresponding changes in the oxide bonds with X-ray photoemission (XPS). We examined two alloy systems: CrNi and AgPd. Both Cr and Ni form strong oxides, while both Ag and Pd form weak ones.