Biomedical subjects

Zhiguo Zhou

Publications and source records attributed to Zhiguo Zhou.

14 recordsLinked to original sources

PubMed2007

Morphology-tunable and photoresponsive properties in a self-assembled two-component gel system.

Photoresponsive C3-symmetrical trisurea self-assembling building blocks containing three azobenzene groups (LC10 and LC4) at the rim were designed and synthesized. By introducing a trisamide gelator (G18), which can self-aggregate through hydrogen bonds of acylamino moieties to form a fibrous network, the mixture of LC10 (or LC4) and G18 forms an organogel with coral-like supramolecular structure from 1,4-dioxane. The cooperation of hydrogen bonding and the hydrophobic diversity between these components are the main contributions to the specific superstructure. The two-component gel exhibits reversible photoisomerization from trans to cis transition without breakage of the gel state.

Journal Article↗

PubMed2006

Modulation of the photochromic property in an organoboron-based diarylethene by a fluoride ion.

Organoboron-based diarylethene was successfully synthesized and exhibited photochromic property. Furthermore, its photochromic property can be modulated by a fluoride ion. The absorption maximum of the photostationary state shifted from 655 to 490 nm upon addition of a fluoride ion. The modulation mechanism is attributed to the special Lewis acid-base interaction between a trivalent boron atom and a fluoride ion.

Journal Article↗

PubMed2006

Fullerene polypyridine ligands: synthesis, ruthenium complexes, and electrochemical and photophysical properties.

Fullerene coordination ligands bearing one bipyridine or terpyridine unit were synthesized, and their coordination to ruthenium(II) formed linear rod-like donor-acceptor systems. Steady-state fluorescence of [Ru(bpy)(2)(bpy-C(60))](2+) showed a rapid solvent-dependent, intramolecular quenching of the ruthenium(II) MLCT excited state. Time-resolved flash photolysis in CH(3)CN revealed characteristic transient absorption changes that have been ascribed to the formation of the C(60) triplet state, suggesting that photoexcitation of [Ru(bpy)(2)(bpy-C(60))](2+) results in a rapid intramolecular transduction of triplet excited state energy. The electrochemical studies on both [Ru(bpy)(2)(bpy-C(60))](2+) and [Ru(tpy)(tpy-C(60))](2+) indicated electronic coupling between the metal center and the fullerene core.

Journal Article↗

PubMed2006

Tether-directed selective synthesis of fulleropyrrolidine bisadducts.

Selective synthesis of C60 bisadducts has been achieved by using the Prato 1,3-dipolar cycloaddition of tethered bis-azomethine ylides. New bis(benzaldehydes) 1-4 tethered by a rigid linker were prepared and used to direct the second cycloaddition of azomethine ylide to C60. Equatorial, trans-4, trans-3, trans-2, and trans-1 bisadducts have been selectively prepared with this approach. However, the introduction of chiral centers in the pyrrolidine rings in the course of the reaction complicated the chemistry, as a number of stereoisomers theoretically could be formed. The structure determination of the isomeric bisadducts was made based on spectroscopic data and theoretical calculations. To our best knowledge, this represents the first example of a systematic study on tether-directed selective synthesis of C60 fulleropyrrolidine bisadducts.

Cross-Linking Reagents↗

PubMed2005

A new method for the functionalization of [60] fullerene: an unusual 1,3-dipolar cycloaddition pathway leading to a C60 housane derivative.

[reaction: see text] A variant of the Huisgen 1,3-dipolar cycloaddition reaction provides a new and convenient functionalization of fullerenes. This method complements the widely used Prato and Bingel-Hirsch reactions. The derived, highly functionalized cyclopentenone and cyclopentenamine fullerene compounds upon hydrolysis are suitable for further functionalization and may serve well in the synthesis of new C60 derivatives possessing uncommon and interesting properties.

Journal Article↗

PubMed2005

[A physiological development time-based simulation model for cotton development stages and square- and boll formation].

In this study, three cotton varieties (CRI 36, CRI 35 and CRI 41) were planted in Nanjing, Anyang, Baoding and Shihezi, respectively, in 2002, and the dynamic relationships between their development and environmental factors were analyzed. Based on this, a simulation model for cotton development stages and square-and boll development was built in terms of physiological development time (PDT). In calculating relative thermal effectiveness, the effect of diurnal temperature differences in different regions on cotton development was incorporated, and the enhancement of plastic mulching on air temperature was quantified. To simulate development stages, the initial fruiting node index (IFIN), sunlight duration factor (FSH), and solar radiation index on fruiting branch (IFBR) were introduced, besides earliness factor of a given genotype. The validation of the model with the data obtained from different years, ecological zones, genotypes, and cultivation practices indicated a high goodness of fitness between the simulated results and observed values. The root mean square error (RMSE) between simulated and observed days from sowing to emergence, emergence to squaring, anthesis to boll opening, and sowing to boll opening was 0.9, 2.2, 1.7, and 2.1 d, respectively, with a mean of 2.1 d, and in all plant sites, the RMSE between simulated and observed days from squaring to boll opening was 1.8-3.7 d, and that from squaring to opening was 4.6-5.8 d.

Gossypium↗

PubMed2005

[Dynamics of soil enzyme activity and nutrient content in intercropped cotton rhizosphere and non-rhizosphere].

The study with high yield cotton-wheat double cropping system showed that soil urease, invertase, protease and catalase activities in intercropped cotton field had the same changing trends with those in mono-cultured cotton field, but were significantly higher in intercropped than in mono-cultured cotton rhizosphere and non-rhizosphere at all development stages of cotton. During the intergrowth period of wheat and cotton, soil nutrient contents in intercropped cotton rhizosphere and non-rhizosphere were lower than or had little difference with those in mono-cultured cotton rhizosphere and non-rhizosphere, but became significantly higher after wheat harvested. The changing trends of soil nutrient contents in intercropped cotton field had little difference from those in mono-cultured cotton field, but the nutrient absorption peak appeared late. The soil enzyme activities and nutrient contents were generally higher in rhizosphere than in non-rhizosphere of both intercropped and mono-cultured cotton. Soil nutrient contents had significant (P < 0.05, n = 32) or very significant (P < 0.01, n = 32) correlation with the activities of soil urease, invertase and protease, but had little correlation with soil catalase activity.

Agriculture↗

PubMed2005

[Quantitative analysis on the relationships between cotton fiber quality and meteorological factors].

With the method of planting cotton by stages at the sites from Yangtze valley to north Xinjiang, this paper studied the effects of air temperature and sunlight on cotton fiber quality in 2002 approximately 2003. The results showed that with increasing latitude, fiber length increased, while micronaire value and soluble sugar content (SSC) decreased. An ecological model describing the relationships of fiber strength, micronaire value and SSC with air temperature and sunlight was built to determine the optimal range and critical value of air temperature during boll development period. If a high quality fiber (length > or = 27 mm) was targeted, the daily mean temperature (DMT) and minimum temperature (Tmin) during this period should be 21.3 approximately 29.7 and 10.7 approximately 21.3 degrees C, respectively, and the daily temperature difference (DTD) should not be > 15.2 degrees C. Fiber length was the longest when the DMT was 25.4 degrees C. If the lowest fiber length was > or = 25 mm, DMT and Tmin should not be lower than 15.5 and 10.7 degrees C, respectively, and DTD should not be over 17.9 degrees C during boll development period.

Cotton Fiber↗

PubMed2004

A new fullerene complexation ligand: N-pyridylfulleropyrrolidine.

The subject of this paper is a new fullerene building block design with the potential for defined geometry and good electronic communication. The synthesis and characterization of a new pyridinofullerene ligand capable of forming axially symmetric complexes with metalloporphyrins is reported. X-ray structural and molecular modeling studies, (1)H NMR, UV-vis spectroscopy, electrochemistry studies, and fluorescence quenching data support the formation of a strong complex between the new ligand and the metal center of ZnTPP. On the basis of computational studies, the highest occupied molecular orbital (HOMO) of this ligand is significantly different from a model compound with insulating carbons between the pyridine and the fullerene. The N-pyridinium fulleropyrrolidine salts of the new ligand and model compound were also prepared and their spectral and electrochemical properties are reported.

Journal Article↗

PubMed2004

[A dynamic knowledge model for nitrogen and water management of cotton].

Through analyzing and extracting the newest research results on nitrogen and water management of cotton, a dynamic knowledge model for decision-making on total nitrogen and water supply levels and their distribution among main growth stages of cotton under different environments and yield targets was developed, with the principles of nitrogen balance and water demand and by integrating the factors of climate, soil, yield and variety. Case studies on the knowledge model with the experiment data sets of different eco-sites, varieties and soil characters indicated a good model performance in decision-making and applicability.

Fertilizers↗

PubMed2004

[Spatial variability and quantitative analysis of field factors based on GIS].

The objective of this research was to investigate the variability and the quantitative relationships among soil nutrients and crop growth status and yield. All data were analyzed by both classical statistics and geostatistics based on GIS. Soil properties included soil pH, total N, organic matter, available P and available K, while crop growth status was indicated by SPAD, LAI and SPAD x LAI. All parameters except soil pH exhibited spatial correlation. Soil total N and organic matter, SPAD, LAI and SPAD x LAI were all correlated to rice yield. Kriged interpolation maps provided good indication of the spatial variability in crop yield and growth status. Spatial interpolation and correlation analysis proved that SPAD x LAI was more indicative of crop growth status than individual variables, and useful for implementing growth season and topdressing as needed.

Biomass↗

PubMed2003

Selective syntheses of novel polyether fullerene multiple adducts.

We have applied a modified macrocyclic tether approach to control multiple additions to C60. The technique of 3He NMR was used to confirm the selective formation of specific C60 multiple adducts by the macrocyclic tether approach. An oligoglycol was used as a flexible linker to produce macrocyclic polyether-linked malonates 5, 6, 8, and 9 under solid-liquid PTC (phase-transfer-catalysis) conditions. The formation of a single C60 tris-adduct, 3, from macrocyclic malonate 1 and 3He@C60 was proven by 3He NMR. Similarly, multiple additions to C60 of macrocyclic polyether malonate 5 gave C60 bis-adduct 10 selectively, while the reaction of C60 with macrocyclic malonate 8 gave bis-adducts 11 and 12. A similar process with macrocyclic malonate 6 gave tris-adduct 13 with high selectivity as well. Saponification of these C60 multiple adducts gives the corresponding polyacids that are potentially useful in biological applications. Macrocyclic polyether fullerenes are a new class of ionophores, which could be interesting for molecular recognition and for the development of biosensors.

Journal Article↗

PubMed2003

Discovery of diverse thyroid hormone receptor antagonists by high-throughput docking.

Treatment of hyperthyroidism, a common clinical condition that can have serious manifestations in the elderly, has remained essentially unchanged for >30 years. Directly antagonizing the effect of the thyroid hormone at the receptor level may be a significant improvement for the treatment of hyperthyroid patients. We built a computer model of the thyroid hormone receptor (TR) ligand-binding domain in its predicted antagonist-bound conformation and used a virtual screening algorithm to select 100 TR antagonist candidates out of a library of >250,000 compounds. We were able to obtain 75 of the compounds selected in silico and studied their ability to act as antagonists by using cultured cells that express TR. Fourteen of these compounds were found to antagonize the effect of T3 on TR with IC50s ranging from 1.5 to 30 microM. A small virtual library of compounds, derived from the highest affinity antagonist (1-850) that could be rapidly synthesized, was generated. A second round of virtual screening identified new compounds with predicted increased antagonist activity. These second generation compounds were synthesized, and their ability to act as TR antagonists was confirmed by transfection and receptor binding experiments. The extreme structural diversity of the antagonist compounds shows how receptor-based virtual screening can identify diverse chemistries that comply with the structural rules of TR antagonism.

Drug Design↗

PubMed2002

[Effect of seedling stage shading on cotton yield and its quality formation].

The effect of shading during symbiotic stage of inter-cropped cotton and wheat on cotton yield and its quality formation was examined by simulated shading at the seedling stage of cotton. The results showed that the effect of shading on the cotton boll formation depended upon the position of fruiting branch and fruiting bud. For the bolls at low(1-3 fruiting branches) and middle(4-6 fruiting branches) parts and the inside bolls(1-2 fruiting buds) on upper(7-9 fruiting branches) fruiting branch, shading favored boll formation, but for the outside bolls (> or = 3 fruiting buds), especially at the top fruiting branch position, shading was unfavorable to boll formation. The effect of shading on the weight of individual boll also depended upon the position of fruiting branch and fruiting bud, but shading did not affect the mean boll weight per plant. For seed cotton yield per plant, the inside boll yield of shaded low and middle fruiting branches was higher than the control, but that of the upper and top fruiting branches was just contrary, the yield of outside bolls of all branches was lower than the control. For the distribution of the inside and outside bolls, shaded cotton was 1:0.36, versus 1:0.58 for the control. For the yield distribution, shaded cotton was 1:0.42, versus 1:0.72 for the control. The effect of shading on the cotton fiber and seed quality was mainly restricted on the bolls of top fruiting branches and the outside bolls of upper fruiting branches. The results also showed that different cotton varieties were different in their shade-tolerance, according to comprehensive analysis of the yield and quality formation, and the shade-tolerance of variety Zh9418 was stronger than that of Zh19 and CAZ.

Cotton Fiber↗