Biomedical subjects

F S Zhang

Publications and source records attributed to F S Zhang.

At least 19 recordsLinked to original sources

PubMed2006

Interception of residual nitrate from a calcareous alluvial soil profile on the North China Plain by deep-rooted crops: a 15N tracer study.

15N-labeled nitrate was injected into different depths of an alluvial calcareous soil profile on the North China Plain. Subsequent movement of NO3- -N and its recovery by deep-rooted maize (Zea mays L.) and shallow-rooted eggplant (Solanum melongena L.) were studied. Under conventional water and nutrient management the mean recoveries of 15N-labeled nitrate from K(15)NO3 injected at depths 15, 45, and 75 cm were 22.4, 13.8, and 7.8% by maize and 7.9, 4.9, and 2.7% by eggplant. The recovery rate by maize at each soil depth was significantly higher than by eggplant. The deeper the injection of nitrate the smaller the distance of its downward movement and this corresponded with the movement of soil water during crop growth. Deeper rooting crops with high root length density and high water consumption may therefore be grown to utilize high concentrations of residual nitrate in the subsoil from previous intensive cropping and to protect the environment.

Biomass↗

PubMed2006

Changes in the soil environment from excessive application of fertilizers and manures to two contrasting intensive cropping systems on the North China Plain.

Effects of excessive fertilizer and manure applications on the soil environment were compared in greenhouse vegetable systems shifted from wheat-maize rotations 5-15years previously and in wheat-maize rotations. N, P and K surpluses to the greenhouses were 4328, 1337 and 1466kgha(-1)year(-1), respectively compared to 346, 65 and -163kgha(-1)year(-1) to wheat-maize fields. Subsequently, substantial mineral N and available P and K accumulated in the soil and leaching occurred down the soil profile in the greenhouses. Soil pH under vegetables was significantly lower than in the wheat-maize fields, while the EC was significantly higher in the vegetable soils. The mean Cd concentration in the vegetable soils was 2.8 times that in the wheat-maize rotations. Due to excessive fertilizer application in greenhouse vegetable production in northeast China, excessive salt and nitrate concentrations may accumulate and soil quality may deteriorate faster than in conventional wheat-maize rotations.

Agriculture↗

PubMed2005

Nitrogen balance and groundwater nitrate contamination: comparison among three intensive cropping systems on the North China Plain.

The annual nitrogen (N) budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systems in Shandong province, north China. In the greenhouse vegetable systems the annual N inputs from fertilizers, manures and irrigation water were 1358, 1881 and 402 kg N ha(-1) on average, representing 2.5, 37.5 and 83.8 times the corresponding values in wheat (Triticum aestivum L.)-maize (Zea mays L.) rotations and 2.1, 10.4 and 68.2 times the values in apple (Malus pumila Mill.) orchards. The N surplus values were 349, 3327 and 746 kg N ha(-1), with residual soil nitrate-N after harvest amounting to 221-275, 1173 and 613 kg N ha(-1) in the top 90 cm of the soil profile and 213-242, 1032 and 976 kg N ha(-1) at 90-180 cm depth in wheat-maize, greenhouse vegetable and orchard systems, respectively. Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15 m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs.

Agriculture↗

PubMed2005

Nitrogen supply after removing the shoot apex increases the nicotine concentration and nitrogen content of tobacco plants.

BACKGROUND: and Aims High nicotine concentrations in leaves, especially in the upper leaves, offer a serious problem for the cultivation of tobacco (Nicotiana tabacum). Preliminary field experiments showed that rapid mineralization of soil N during late stages of growth may contribute to high nicotine concentrations in leaves. METHODS: A sand-culture experiment was carried out in the greenhouse. The N supply was controlled during the experiment, and different amounts of 15N were supplied during late stages of growth (after removal of the shoot apex), to investigate the contribution of the N taken up at this time to the N content of and nicotine concentration in tobacco plants. KEY RESULTS: Addition of 1.6 g or 4 g 15N-labelled NH4NO3 after removing the shoot apex and flushing out the 14N did not increase leaf dry weights; however, it did result in delayed leaf senescence, more lateral bud formation, and an increase in 15N as a proportion of total N, and nicotine-15N as a proportion of total nicotine-N in each organ. The nicotine concentration, 15N and nicotine-15N abundances were increased from the bottom to the top leaves. When more 15N-labelled NH4NO3 was supplied, the nicotine concentration in leaves increased, and so did the 15N abundance in nicotine-N. CONCLUSION: Enhanced N supply in the later growth stages (after removing the apex) increased N content and nicotine concentration in tobacco plants. Nicotine was synthesized de novo during the late growth stages.

Nicotine↗

PubMed2005

Transpiration, potassium uptake and flow in tobacco as affected by nitrogen forms and nutrient levels.

BACKGROUND AND AIMS: Ammonium can result in toxicity symptoms in many plants when it is supplied as the sole source of N. In this work, influences of different nitrogen forms at two levels (2 and 15 mm N) on growth, water relations and uptake and flow of potassium were studied in plants of Nicotiana tabacum 'K 326'. METHODS: Xylem sap from different leaves was collected from 106-d-old tobacco plants cultured in quartz sand by application of pressure to the root system. Whole-shoot transpiration for each of the treatments was measured on a daily basis by weight determination. KEY RESULTS: Total replacement of NO(3)(-)N by NH(4)(+)-N caused a substantial decrease in dry weight gain, even when plants grew under nutrient deficiency. Increasing nutrient concentration resulted in a greater net dry weight gain when nitrogen was supplied as NO(3)(-) or NH(4)NO(3), but resulted in little change when nitrogen was supplied as NH(4)(+). NH(4)(+)-N as the sole N-source also caused reduction in transpiration rate, changes in plant WUE (which depended on the nutrient levels) and a decrease in potassium uptake. However, the amount of xylem-transported potassium in the plants fed with NH(4)(+) was not reduced: it was 457 % or 596 % of the potassium currently taken up at low or high nutrient level, respectively, indicating a massive export from leaves and cycling of potassium in the phloem. CONCLUSIONS: Ammonium reduces leaf stomatal conductance of tobacco plants. The flow and partitioning of potassium in tobacco plants can be changed, depending on the nitrogen forms and nutrient levels.

Biological Transport↗

PubMed2005

Solvent-induced symmetry breaking: varying solvent strength.

The triiodide ion is an example of a system where symmetry breaking may be induced by a solvent. The Landau free energy is expected to have a similar form to that for the mean field Ising model, but with solvent strength rather than temperature as the control parameter determining whether there is symmetry breaking. In order to examine the extent of anomalous behavior near the critical point we have studied the properties of the ion in a solvent based on a model for water with charges scaled by a factor lambda . As lambda is increased from zero the solvent strength increases and the system changes from one with no symmetry breaking to one with strong symmetry breaking. The Shannon entropy as a function of lambda shows only a weak maximum near the critical value of lambda= lambda(c) , while the susceptibility has no anomalous behavior. We examine a simple model and show that anomalies near the critical point would increase as the temperature decreases, but divergences associated with a second order phase transition would only be seen in the limit of zero temperature.

Journal Article↗

PubMed2004

Acid phosphatase role in chickpea/maize intercropping.

BACKGROUND AND AIMS: Organic P comprises 30-80 % of the total P in most agricultural soils. It has been proven that chickpea facilitates P uptake from an organic P source by intercropped wheat. In this study, acid phosphatase excreted from chickpea roots is quantified and the contribution of acid phosphatase to the facilitation of P uptake by intercropped maize receiving phytate is examined. METHODS: For the first experiment using hydroponics, maize (Zea mays 'Zhongdan No. 2') and chickpea (Cicer arietinum 'Sona') were grown in either the same or separate containers, and P was supplied as phytate, KH2PO4 at 0.25 mmol P L(-1), or not at all. The second experiment involved soil culture with three types of root separation between the two species: (1) plastic sheet, (2) nylon mesh, and (3) no barrier. Maize plants were grown in one compartment and chickpea in the other. Phosphorus was supplied as phytate, Ca(H2PO4)2 at 50 mg P kg(-1), or no P added. KEY RESULTS: In the hydroponics study, the total P uptake by intercropped maize supplied with phytate was 2.1-fold greater than when it was grown as a monoculture. In the soil experiment, when supplied with phytate, total P uptake by maize with mesh barrier and without root barrier was 2.2 and 1.5 times, respectively, as much as that with solid barrier. In both experiments, roots of both maize and chickpea supplied with phytate and no P secreted more acid phosphatase than those with KH2PO4 or Ca(H2PO4)2. However, average acid phosphatase activity of chickpea roots supplied with phytate was 2-3-fold as much as maize. Soil acid phosphatase activity in the rhizosphere of chickpea was also significantly higher than maize regardless of P sources. CONCLUSIONS: Chickpea can mobilize organic P in both hydroponic and soil cultures, leading to an interspecific facilitation in utilization of organic P in maize/chickpea intercropping.

Acid Phosphatase↗

PubMed2003

Solvent-induced symmetry breaking.

Symmetry breaking can be induced in a number of ways including interactions with a solvent. An example is the triiodide ion which is centrosymmetric in the gas phase. Molecular dynamics simulations of the triiodide ion in solution have been used to investigate the extent of symmetry breaking in a variety of solvents. We find that the triiodide ion loses its symmetry in water, ethanol, and methanol which form hydrogen bonds with the ion. This results in a localization of charge at one end of the ion and breaking of the geometric symmetry. The extent of symmetry breaking increases as the temperature is lowered. Correlation times for interconversion are reported and the energetics of symmetry breaking are presented. Analogies are made with second-order phase transitions.

Journal Article↗

PubMed2002

Improved tolerance of maize plants to salt stress by arbuscular mycorrhiza is related to higher accumulation of soluble sugars in roots.

The effect of colonization with the arbuscular mycorrhizal (AM) fungus Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe on the growth and physiology of NaCl-stressed maize plants ( Zea mays L. cv. Yedan 13) was examined in the greenhouse. Maize plants were grown in sand with 0 or 100 mM NaCl and at two phosphorus (P) (0.05 and 0.1 mM) levels for 34 days, following 34 days of non-saline pre-treatment. Mycorrhizal plants maintained higher root and shoot dry weights. Concentrations of chlorophyll, P and soluble sugars were higher than in non-mycorrhizal plants under given NaCl and P levels. Sodium concentration in roots or shoots was similar in mycorrhizal and non-mycorrhizal plants. Mycorrhizal plants had higher electrolyte concentrations in roots and lower electrolyte leakage from roots than non-mycorrhizal plants under given NaCl and P levels. Although plants in the low P plus AM fungus treatment and those with high P minus AM fungus had similar P concentrations, the mycorrhizal plants still had higher dry weights, soluble sugars and electrolyte concentrations in roots. Similar relationships were observed regardless of the presence or absence of salt stress. Higher soluble sugars and electrolyte concentrations in mycorrhizal plants suggested a higher osmoregulating capacity of these plants. Alleviation of salt stress of a host plant by AM colonization appears not to be a specific effect. Furthermore, higher requirement for carbohydrates by AM fungi induces higher soluble sugar accumulation in host root tissues, which is independent of improvement in plant P status and enhances resistance to salt-induced osmotic stress in the mycorrhizal plant.

Fungi↗

PubMed2002

Effect of La3+ on the activities of antioxidant enzymes in wheat seedlings under lead stress in solution culture.

In order to improve the plant ability to resist lead stress, effect of 0.05 mg/l La(NO3)3 on the activities of catalase (CAT), superoxide dismutase (SOD), the level of malondialdehyde (MDA) in wheat seedlings under lead stress was studied. The effect of La3+ on plant growth, chlorophyll content in wheat seedlings after adding 0, 50, 100 mg/l Pb(NO3)3 to the nutrient solution for 12 days was observed. The plants were grown in nutrient solution in a strictly controlled climate growth room. Effects of La3+ (with La treatment) compared with check groups was evidently observed. The activities of SOD and CAT in root were enhanced 0.45-1.69 times and 33.20-77.77% respectively and MDA content was reduced 11.05-27.49% in root after treatments from the second day till the end of the experiment. The activities of SOD and CAT was found to be increased slightly (P < 0.05) and MDA content decreased in shoot and root of wheat seedlings by La3+ under lead stress within five days after treatments compared with Pbl and Pb2 groups. It was assumed that antioxidant enzymes was found to be increased by La(NO3)3, the antioxidant potential of the wheat seedlings to resist lead stress enhanced. It is suggested that La3+ could be used to resist lead stress at the beginning under stress while the stress was not so serious.

Catalase↗

PubMed2001

Application of waste ashes to agricultural land--effect of incineration temperature on chemical characteristics.

Incineration is one of the most important methods of municipal waste disposal. During incineration, various reactions of composition and decomposition may occur; the physical and chemical properties of municipal wastes may change to a great extent. In the present study, 15 samples, including food scraps (FS), animal wastes (AW) and sewage sludges (SS) were collected from various places in Japan, incineration treatments at 500 degrees C, 850 degrees C and 1000 degrees C were conducted in laboratory, and pH, EC, P content, various P forms, anions and soluble metals were determined. The results indicated that average pH increased by 1.09, 1.84, 2.27 and EC decreased by 4.6, 4.6, 5.6 ds m(-1) at 500 degrees C, 850 degrees C, 1000 degrees C, respectively, pH increased in the sequence of AM > SS > FS, and the decrease rate of EC was in the order of FS > SS > AM. Compared with no treatment (NT), water-soluble P decreased greatly at all three temperatures; available P increased at 500 degrees C, but decreased to the original level at 850 degrees C and 1000 degrees C; the amount of Ca-P, Fe-P and Al-P decreased and residual insoluble P increased greatly at 850 degrees C and 1000 degrees C; no significant change of total P was found at all three temperatures. However, water-soluble HPO4(2-) and Cl- decreased greatly, the decrease ratio of Cl- was in the sequence of SS > FS > AM at 500 degrees C, and FS > SS > AM at 850 degrees C and 1000 degrees C; no significant difference was found for HPO4(2-) among all three treatment temperatures; water-soluble SO4(2-) decreased at 1000 degrees C, but there was no significant change at 500 degrees C and 850 degrees C. Moreover, water-soluble Na, Mg, K, Ti, Mn, Fe, Ga, Cd, Zn, Ba, Pb, Sr, W and 0.1 M HNO3 soluble Al, K, Cr, Mn, Fe, Zn, Sr, Ba, Pb, Be, Ga, Rb, Cd, Sn, Sb, Ta, Tl, Bi, Na, Co, Ni, Sc, Cs decreased, but water-soluble Ca, Cr, Co, Ni and 0.1 M HNO3 soluble Cu, Ca, V, Mo, W, Th, U, Hf increased at 500 degrees C, 850 degrees C or 1000 degrees C.

Agriculture↗

PubMed2001

Rare earth element content in various waste ashes and the potential risk to Japanese soils.

Selected chemical characteristics of rare earth elements (REEs) in 89 waste ash samples, including food scrap ashes (FSA), animal waste ashes (AWA), horticulture waste ashes (HWA), sewage sludge ashes (SSA) and incinerator bottom ashes (IBA), were examined in this study. The results showed that Y, La, Ce, Pr, Nd, Dy, Yb, Ho, Er, Tm, Lu in the waste ash samples were normally distributed, but Sc, Sm, Eu, Gd, Tb were not. Average REE concentrations followed the sequence of Ce > La = Y> Sc>Nd>Sm>Pr>Gd>Dy>Eu>Tb>Er> Yb>Ho>Lu>Tm. Of the five types of waste ashes, total REE contents (sigmaREE) ranged from 54 to 130 mg/kg, following the sequence of SSA>HWA>IBA>AWA>FSA; individual REE concentrations were within 0.04-20, 0.1-29, 0.2-33, 0.1-44 and 0.01-41 mg/kg for FSA, AWA, HWA, SSA and IBA, respectively. Crust-normalized REE patterns indicated that SSA was enriched with Sc, Sm, Eu, Gd, Tb and slightly enriched with La, Ce; IBA was enriched with Eu, Tb and slightly with La, Y, Ce; FSA was slightly enriched with Sm, Eu, Tb; REEs were not found to be elevated in HWA and AWA. Comparison of REE content in the waste ashes and in six principal Japanese agricultural soils indicated that application of FSA, AWA and HWA to agricultural land will cause no REE problem, but continuous application of SSA or IBA may cause Sc, Sm or Eu accumulation in some of the soils.

Agriculture↗

PubMed2001

Evaluation of cadmium and other metal losses from various municipal wastes during incineration disposal.

The Japanese intake much more Cd through food than people in other countries, this may be partly caused by the activity of municipal waste incineration disposal. The present study was carried out to examine the behavior of Cd and to identify the other lost metals during municipal waste incineration. Thirty-eight waste samples, including food scraps (FS), animal wastes (AW), horticulture wastes (HW) and sewage sludges (SS) were collected from various places in Japan. Treatment temperatures of 500, 850, and 1000 degrees C were conducted to these samples in laboratory, and thirty-nine kinds of metals were examined. The results showed that average Cd losses were 69% (2.4 mg kg-1) and 74% (2.6 mg kg-1) at 850 and 1000 degrees C, respectively. Furthermore, the losses of 20 other metals were also found, i.e. Sn lost at 500 degrees C, K, Mg, Na, Bi, Cr, Ge, Li, Pb, Sn, Tl, Zn lost at 850 degrees C, and nine more metals, Al, Be, Cs, Nb, Sb, Sr, Th, Y, Zr lost at 1000 degrees C. The lost metals were considered to be transferred into the combustion flue gas, mainly in the forms of metallic chloride compounds, e.g. CdCl2, SnCl4, SnCl2, ZnCl2, PbCl2, etc. On the other hand, no significant losses for Ca, Fe, Ag, Ba, Co, Cu, Ga, Hf, Mn, Mo, Ni, Rb, Sc, Ta, Ti, U, V, W were found at 0.05 probability level. Total metal losses could be calculated at 9.9 and 20 g kg-1, in which major metal (Al, K, Mg, Na) losses were 9.5, 19 g kg-1 and minor and trace metal losses were 0.4, 0.6 g kg-1 at 850 and 1000 degrees C, respectively. Among the four types of waste materials, Cd losses were 0.8-3.7 mg kg-1, occupied about 60-80% at 850 degrees C, and 0.9-3.9 mg kg-1, occupied about 65-85% at 1000 degrees C. The total major metal losses from the four types of waste materials could be calculated at 6.5-15 g kg-1 at 850 degrees C, and 11-31 g kg-1 at 1000 degrees C, minor and trace metal losses were 0.03-1.3 g kg-1 at 850 degrees C, and 0.3-1.5 g kg-1 at 1000 degrees C, respectively.

Agriculture↗

PubMed2001

[Differential accumulation of the new high-affinity phosphate transporter candidated gene fragment in rice roots in response to phosphorus deficiency stress].

Phosphate is a major constraint to crop production, and phosphate uptake in plant is mainly by high-affinity phosphate transporter under phosphate deficiency condition. Using RT-PCR, a 1,178 bp phosphate transporter gene fragment OjPT1 was cloned from roots of Jingxi17 (Oryza sativa L. ssp. japanica) supplied with no phosphate. The comparison of this sequence with ones in GenBank indicated that it shared about 70% similarity at amino acid level with other phosphate transporters in higher plants, such as Arabidopsis thaliana, potate, tamato, Medicago truncatula and Catharanthus roseus, and high similarity with phosphate transporters in Saccharomyces cerevisiae and Neurospora crassa. RT-PCR assay showed that the OjPT1 transcripts were induced under phosphate deficiency condition. This gene fragment OjPT1 has been deposited in GenBank (accession No. AF249619).

Amino Acid Sequence↗

PubMed2001

Effect of long-term fertilization on soil nitrate distribution.

A thirteen years long-term field fertilizer experiment was conducted to monitor the effect of different fertilization on soil nitrate distribution. The results showed: (1) Applying relative excessive N fertilizer could result large quantities of NO3- residue and NO3- movement downward in soil profiles; amending phosphate fertilizer or organic manure with nitrogen fertilizer together could significantly improve the status of NO3- leaching downward due to the balanced uptake of nutrients by crops. (2) Appropriate amounts of nitrogen fertilizer which was equal or smaller than the optimal fertilization rate could not result in more NO3- leaching in Northern China. (3) Precipitation influenced the amounts and depth of soil NO3- leaching: NO3- could move to 80 cm depth or below at autumn or at the next spring when rainfall was higher during the rainy season through July to September in North China.

Agriculture↗

PubMed2001

[Relationship between EGG and the dynamic process of motion sickness induced by optokinetic vection].

OBJECTIVE: To investigate the correlation between Electrogastrography (EGG) and the occurrence of nausea or/and vomit as well as the development of motion sickness (MS) induced by optokinetic stimulation (OPS) and to provide a clue and method for prediction and prevention of MS. METHOD: Twenty male subjects, aged from 18 to 25 years, performed the test only once with the optokinetic drum rotated around a vertical axis at the speed of 60 degrees/s for 15 min. Nausea and EGG signals were observed and recorded. RESULT: (1)Both the increment of tachygastric percentage and the decrement of primary wave percentage of EGG in eleven subjects with nausea were significantly larger than those in nine subjects with no nausea (both P < 0.001). (2)The circular vection preceded the changes of EGG in eleven subjects with nausea while the MS scores in eleven subjects with nausea were higher than those in nine subjects with no nausea (P < 0.001). (3)During the rotation of drum, the decrement of primary wave percentage or the increment of tachygastria percentage also preceded the occurrence of nausea in eleven subjects with nausea (both P < 0.01). CONCLUSION: (l)The changes of EGG in subjects with nausea were significantly greater than those of EGG in subjects with no nausea. (2)There was a close relationship between circular vection or illusory self-rotation and EGG changes as well as the occurring of nausea induced by OPS. (3)Changes of EGG preceded the nausea of MS induced by OPS.

Adolescent↗

PubMed2000

Does aluminum inhibit pollen germination via extracellular calmodulin?

The effect of aluminum (Al) on pollen germination and its mechanism of action were investigated. Pollen germination and pollen tube elongation were inhibited by Al at pH 4.5. This inhibitory effect was reversed by the addition of purified calmodulin (CaM), whereas neither the calcium binding-protein S-100 nor Al chelator citric acid at the same concentrations had any obvious effect on Al-inhibited pollen germination. The presence of either the membrane-impermeable CaM inhibitor anti-CaM antiserum or Ca2+ chelator EGTA completely suppressed the effect of exogenous CaM. These results indicate the involvement of extracellular calmodulin in the short-term effects of Al on pollen germination and pollen tube elongation.

Aluminum Chloride↗

PubMed2000

[Effects of different training methods on cardiovascular autonomic regulation during bedrest].

Objective. To investigate the effects of different training methods on cardiovascular autonomic regulation under bedrest. Method. 15 healthy male volunteers aged 19-22 participated tests in head-down tilt (HDT) -6 degrees bedrest in order to observe the changes of cardiovascular system under simulated weightlessness. They were divided into control (5 men), hypoxia training (5 men) and Fangsong training (5 men) groups. 24 h dynamic ECG were recorded on the 2nd day of pre-bedrest, on the 3rd, 14th and 18th day of bedrest and on the 7th day of the post- bedrest. All spectra were estimated from entire 24 h HRV, before, during and after Fangsong and hypoxia training by autoregressive (AR) modeling method. Normalized low-frequency (LF%) was a quantitative marker of cardiac sympathetic activity, normalized high-frequency (HF%) reflected the changes in cardiac vagal activity, and LF/HF was considered to be related to sympathovagal balance or sympathetic activity. Result. In control group, LF% and HF% were all significantly reduced (P<0.05), LF/HL showed no significant changed during bedrest. In Fangsong group, HF% increased markedly (P< 0.05), while in hypoxia group, LF% increased markedly (P< 0.05). Conclusion. Fangsong training counteracted markedly the reduction in vagal activity, while hypoxia training counteracted markedly the decrease in sympathetic activity. It was possible that HRV indices could be used to evaluate the efficiency of countermeasures counteracting the adverse effects of weightlessness.

Adaptation, Physiological↗