Search Results

You are looking at 1 - 10 of 13 items for

  • Author or Editor: H. J. He x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

Two series of antibacterial compounds were synthesized using montmorillonite and chlorhexidine acetate (CA) by ion-exchange reaction. The resulting samples were characterized by high-resolution thermogravimetric analysis (HRTG), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and their antibacterial activity was assayed by halo method. In this study, the loaded amounts of CA in the resultant compounds were evaluated by the HRTG curves. CA adopts a lateral monolayer arrangement in the resulting samples with low CA loading, while a special state with partial overlapping of organic molecules is supposed for the resulting samples prepared at 1.0–4.0 CEC. After the intercalation with CA, the hydrophilic surfaces of montmorillonite are changed to hydrophobic ones, reflected by the frequency shift of the symmetric ν1(O-H) stretching vibration from low to high. This study shows that the interlayer cations in raw montmorillonite have little influence on the structure of the resulting samples. Antibacterial activity test against E. coli demonstrates that the antibacterial activity of the resulting samples strongly depends on the content of the loaded CA and these resulting materials show a long-term antibacterial activity that can last for at least one year.

Restricted access

Abstract  

Supramolecular 2,3- and 2,5-pyridinedicarboxylate (PDC) intercalated ZnAl-layered double hydroxides (2,3- and 2,5-PDC–ZnAl–LDHs) have been prepared by ion exchange method. The structure and composition of the intercalated materials have been studied by X-ray diffraction (XRD) and inductively coupled plasma emission spectroscopy (ICP). The study indicates that the 2,3-PDC and 2,5-PDC anions are accommodated as interdigitated bilayer and monolayer arrangement respectively between the sheets of LDHs. Furthermore, their thermal decomposition processes were studied by the use of in situ high temperature X-ray diffraction (HT-XRD), and the combined technique of thermogravimetry-differential thermal analysis-mass spectrometry (TG-DTA-MS) under N2 atmosphere. Based on the comparison study on the temperatures of both decarboxylation and complete decomposition of interlayer PDC, it can be concluded that 2,5-PDC–ZnAl–LDHs has higher thermal stability than that of 2,3-PDC–ZnAl–LDHs.

Restricted access

Abstract  

The combustion behavior of Shuangya Mountain (SYM) coal dust has been investigated by means of TG in this paper. The reaction fraction can be obtained from isothermal TG data. The regressions of g(), an integral function of vs. t for different reaction mechanisms were performed. The mechanism of nucleation and nuclei growth is determined as the controlling step of the coal dust combustion reaction by the correlation coefficient of the regression, and the kinetic equation of the SYM coal dust combustion reaction has been established.

Restricted access

The geographical patterns of tree species richness in forest communities have been studied widely, but little is known about the geographical variation of the estimated species richness and minimum areas using species-area curves. A differential technique based on the species-area relationships (SAR) was developed for estimating the minimum area (Amin) capturing 60- 80% of the species in each plot, which is an important characteristic of a forest community. The relationship between estimated species richness (ESR) from the SAR and the corresponding minimum area is described by the linear model ESR = 0.0051×Amin (R2 = 0.98, p < 0.0001). Both the ESR and the minimum area exhibit similar geographical variations with a significant increase along altitudinal and a decrease along latitudinal gradients. The spatial variations of the ESR were partitioned into three geographical components and their combined effects. Altitude accounted for 40% and 45% of the total variation in the ESR and the minimum area, respectively. While latitude accounted for 69% and 61% of the total variation in the ESR and the minimum area, respectively. Thus, latitude is the main determinant which influences the geographical variation of the ESR. As far as we know, this study presents the first report of the geographical patterns of the minimum area in temperate forests.

Restricted access

A rapid and sensitive method for the identification and quantification of phillyrin (POG) in Forsythia suspense is described. The phillyrin standard solution was directly infused into the ion trap mass spectrometers (IT-MS) for collecting the MS n spectra. The electrospray ionization (ESI) mass spectral fragmentation pathway of phillyrin was proposed, and the ESI-MS n fragmentation behavior of phillyrin was deduced in detail. The major product ion at m/z 355 belongs to furofuran, which was formed by loss the glucopyranoside (180 Da), and the characteristic fragment ions m/z 473, 395, 337, 309, and 249 were observed. The loss of 18 Da could arise from two different fragmentation pathways, and the observed ion was composed of a mixture of two different structural ions. Quantification of phillyrin was assigned in positive-ion mode at a product ion at m/z 557 → 355 by liquid chromatography-mass spectrometry (LC-MS). The LC-MS method was validated for linearity, sensitivity, accuracy, and precision and then used to determine the content of the phillyrin. Lastly, the LC-MS method was successfully applied to determine phillyrin in real sample F. suspense and three of its medicinal preparations in the positive mode at the first time.

Open access

Abstract  

A series of anion-cation surfactants modified organoclays are prepared by incorporating both cationic surfactant, hexadecyltrimethylammonium bromide (HDTMAB), and anionic surfactant, sodiumdodecyl sulfonate (SDS), to montmorillonite. The added amounts of surfactant varied from 0.2 to 4.0 CEC of the used montmorillonite, similar to those reported in literature. A combination of elemental analysis, X-ray diffraction and thermogravimetric analysis is used in the characterization of the resulting organoclays. The experimental results show that anionic surfactants can not be intercalated into the montmorillonite whereas they can be loaded onto cationic modified montmorillonite, resulting in a further increase of organic carbon content of the resulting organoclays. This study demonstrates that SDS can be intercalated into montmorillonite interlayer space through the interaction with HDTMAB rather than by ion exchange. The intercalation of SDS results in an increase of the basal spacing of the resulting organoclays when comparing with HDTMAB modified montmorillonite and higher decomposition temperature of the intercalated surfactants when comparing with them in bulk state. These new insights are of high importance in the application of organoclays in the fields of remediation of polluted water and synthesis of clay based nanocomposites.

Restricted access

Abstract

This paper provides a rapid method coupled with chemometrics to visualise PEL quality of eight regions. The contents of mineral elements, Vitamin C (Vc), and colour parameters were measured using spectrophotometric methods. The volatile substances were determined by electronic nose (E-nose) and headspace solid phase micro-extraction with gas chromatography-mass spectrometry (HS-SPME/GC-MS). Chemometric analyses were employed to visualise the sample distribution according to the geographical origin. The colour parameters, Vc, and mineral contents of PEL from diverse origins were significantly different (P < 0.05). A total of 25 volatile organic compounds (VOCs) were identified from PELs, with the highest percentage of components being ethyl acetate. The combination of HS-SPME/GC-MS and E-nose can properly characterise PEL samples. Therefore, the results of this exploratory work highlight the possibility of discriminating PEL from different regions.

Restricted access

Abstract

Chinese onion (Allium chinense G. Don) is an edible vegetable as well as a traditional Chinese medicine. It is rich in steroidal saponins and possesses broad health benefits. In this study, the optimal extraction protocol of the total saponins from Chinese onion (ACS) was explored, and the content of the total steroidal saponins in ACS reached 56.62%. Network pharmacology was applied to predict the related signalling pathways and targets between the main phytochemicals in ACS and hypercholesterolaemia. Enrichment analysis showed that ACS might intervene hypercholesterolaemia through the PI3K-Akt signalling pathway. Meanwhile, cholesterol-lowering effects were verified by ACS intervention in high-cholesterol diet-induced hypercholesterolaemia in Kunming mice. Compared with the model group, the TC and LDL-C levels of mice were decreased and the HDL-C level increased significantly after administration of ACS at a dose of 200 mg kg−1 day−1. The body weight gain, liver index, and atherosclerosis index all decreased dramatically. ACS could significantly reduce the fat content in the liver and reduce the number of fat droplets from the haematoxylin and eosin (H&E) staining of mouse liver. The immunohistochemical staining indicated that ACS could up-regulate the expression of PI3K protein in the liver, thus playing an anti-hypercholesterolaemic role. This study indicated that ACS exhibited significant therapeutic and preventive effects on hypercholesterolaemia, and exerted anti-hypercholesterolaemia through the PI3K-Akt signalling pathway.

Open access

Abstract  

The characterization of different sized TiO2 (25 nm, 80 nm, and 155 nm) was carried out by transmission electron microscopy (TEM) and the micro-distributions of TiO2 in the olfactory bulb of mice after nasal inhalation were investigated by microbeam SRXRF mapping techniques. The results show that TiO2 particles can be translocated to the olfactory bulb through the olfactory nerve system after inhalation. The distributions of Fe, Cu, and Zn in the olfactory bulb were also studied.

Restricted access

Thinopyrum intermedium, which has many useful traits, is valuable for wheat breeding. A new wheat-Thinopyrum addition line, SN100109, was developed from the progeny of common wheat cultivar Yannong 15 and Th. intermedium. It was resistant to most races of Blumeria graminis f. sp tritici (Bgt), which caused powdery mildew in wheat, and its reactions were different from the reactions of gene Pm40 and Pm43. Genomic in situ hybridization (GISH) and molecular marker analysis were used to identify the genomic composition of SN100109. GISH results showed that SN100109 was a wheat-Th. intermedium disomic addition line containing one pair of J chromosomes, and the resistance gene was located on the alien additional chromosomes of SN100109. And four molecular markers BE425942, BF482714, Xgdm93 and BV679214 which were assigned to homologous group 2, were specific molecular markers of the additional chromosomes. All the results indicated that SN100109 contained one pair of 2J chromosomes. SN100109 can be used as a novel germplasm source for introducing powdery mildew resistance genes to wheat in breeding programs.

Restricted access