梭罗《瓦尔登湖》的审美观照

本文旨在探讨一种解读自然文学作品的审美阐释方法。在梳理相关哲学、美学理论的基础上,本文提出"心湖映照"镜观图式和"山湖映带"游观图式,然后通过细读《瓦尔登湖》中涉及"观湖"的部分文本,阐析了梭罗的"观湖"审美体验过程。研究认为,引入山水美学视角可为解读《瓦尔登湖》开辟新路径,也能为阐释其他自然文学作品提供一些借鉴。

Micro-galvanic corrosion behaviour of Mg-(7,9)Al-1Fe-xNd alloys

The localized micro-galvanic corrosion process and the kinetic information of Mg-(7,9)Al-1Fe-x Nd alloys were investigated by in situ observation under electrochemical control and in situ atomic force microscopy(AFM)in an electrolyte environment.The results revealed that the formation of the Nd-rich phase in alloys resulted in a decrease in the Volta potential difference from~400 m V(AlFe3/α-Mg)to~220 mV(Nd-rich/α-Mg),reducing the corrosion products around the cathodic phase and corrosion current density of the microscale area.The addition of Nd significantly improved the corrosion resistance,mainly due to the suppression of the micro-galvanic corrosion between the second phases and substrate.Finally,the corrosion mechanism of Mg-(7,9)Al-1Fe-x Nd alloys was discussed based on in situ observations and electrochemical results.

Relationship Between Leaf Structure and Aloin Content in Six Species of Aloe L.

The leaf structure, content and the storage location of aloin in the leaves of six species of Aloe L. were studied by means of semi-thin section, high performance liquid chromatography (HPLC) and fluorescent microscope. Results showed that all leaves consisted of epidermis, chlorenchyma, aquiferous tissue and vascular bundles. The leaves had the xeromorphic characteristics, including thickened epidermal cell wall, thickened cuticle, sunken stomata and well-developed aquiferous tissue. With the exception of thus, there were remarkable differences in leaf structure among the six species. The chlorenchyma cells were similar to palisade tissues in Aloe arborescens Mill. and A. mutabilis Pillans, but isodiametric in A. vera L., A. vera L. var. chinensis Berg., A. saponaria Hawer and A. greenii Bali. A. arborescens, A. mutabilis, A. very and A. vera var. chinensis included large parenchymatous cells at the vascular bundles, whereas no such cells were observed at the vascular bundles of A. saponaria and A. greenii. In A. arborescens, A. mutabilis and A. vera, the aquiferous tissue sheaths were present and composed of a layer of small parenchymatous cells without chloroplasts around the aquiferous tissue. While there were no aquiferous tissue sheaths in A. vera var. chinensis, A. saponaria and A. greenii. The HPLC revealed that the content of aloin was high in A. arborescens, low in A. vera, and very low in A. saponaria among the six species. The fluorescent microscopy showed that the yellow-green globule only appeared in the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath, but not in the chlorenchyma and aquiferous tissue. Consequently, the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath were the storage location of aloin. They were positively correlated with the content of aloin.

Observation and characterization of asphalt microstructure by atomic force microscopy

The microstructure of asphalt is investigated by atomic force microscopy （AFM）. In order to analyze the impacts of asphalt types on microstructures, two neat asphalts with different penetration grades （50# and 70#） and one styrene-butadiene-styrene （SBS） modified asphalt are chosen. The influence of short-term aging is also studied. Based on the knowledge of asphalt＇s microproperties, the relationship between microstructures and healing property is analyzed. The results indicate that the microstructures of three asphalts are quite different and the effects of aging on the surface characteristics for different asphalts are also different. It is proposed that the bee structure is a type of wax crystal and it has a close relationship with the ＂bridge-healing＂ mechanism. The findings may reveal the formation mechanism of microstructure and the healing property for asphalts.

Scanning Electron Microscope Observation of Three Species on Pollen Grain Morphology and Leaf Epiderm Shape in Gramineae Triticeae

The pollen grain morphology and leaf epiderm shape and microstructural of Rye（ Secale cereal ）, common wheat and Octoploid Trititrigia were observed with the scanning electron microscope（SEM）. The results revealed that there were great differences between pollen and leaf epiderm microcosmic morphology in three species. Such characteristics of Octoploid tnticalwere between those of common wheat and Rye. The morphology of pollen grain and leaf epiderm shape counld be used as an index for taxonomy for genera and species, and had somewhat scientif- ic references to identify new multiploid species created by chromosome engineering.

Fracture characteristics of notched investment cast TiAl alloy through in situ SEM observation

TiAl alloys were produced by investment casting method combined with induction skull melting （ISM） technique. In situ scanning electron microscopy （SEM） was utilized to study the fracture characteristics and crack propagation of a notched investment cast TiAl specimens in tension under incremental loading conditions. The whole process of crack initiation, propagation and failure during tensile deformation was observed and characterized. The results show that the fracture mechanism was sensitive to not only the microcracks near the notched area but also lamellar orientation to loading axis. The high tensile stress leads to the new microcracks nucleate along lamellar interfaces of grains with favorable orientation when local stress intensity reaches the toughness threshold of the material. Thus, both plasticity and high tensile stress are required to cause notched TiAl failure.

Transmission Electron Microscopy Observation of Different Callus Structures in Heiya No.14

[ Objective] The aim was to observe the ultrastructure of different callus structures in Heiya No. 14 by transmission electron microscopy. [Methods] Sample preparation and observation were both carried out by conventional transmission electron microscopy. [ Results] It was showed by transmission electron microscopy that the initial callus cells had a large central vacuole, which squeezed its cytoplasm to be a thin layer around the brim of cell, Meanwhile the nuclear was also squeezed to distribute in the corner of cell, but its nucleolus could be still observed; Compared embryogenic callus with initial callus, its cell wall became thick, and many starch grains and chloroplasts including starch grains could be observed in the cytoplasm area of cell membrane; In non-embryoenic callus, no organelles except for the vacuole could be observed; In browning callus, there was almost no organelles in cells. [ Conclusion] There are significant differences in different types of flax callus at the cell ultrastructure level, which can be as an index for reflecting the differentiation ability of callus cell.

Research on Pollen Grains of Tetraploid Lines and Diploid Control Line of Chrysanthemum cinerariifolium (Trev.) Vis.

[Objective] The aim was to study characters of pollen grains of tetraploid lines and diploid control line of Chrysanthemum cinerariifolium (Trev.) Vis.,morphological characters,fertility of pollen grain and germination percentage of seeds. [Method] Pollen grains were prepared by sulphuric acid-acetyl oxide decomposition method. The lengths of polar axis and equatorial axis of pollen grains were determined with general optical microscope. The morphology of pollen grains was observed with SEM (scanning electron microscope) and the typical visual fields of 2 500× (or 2 000×),7 000× were taken pictures. [Result] Comparing with the diploid control line,the pollen grains of five tetraploid lines which were tested were different from the diploid line in morphology,sculpture,etc.. 4 of the 5 tested samples were significant larger than the diploid line in size and one was similar to the diploid line. [Conclusion] This research provided references for breeding tetraploid improved varieties of Chrysanthemum cinerariifolium (Trev.) Vis. with good fertility and high germination percentage.

Obsevation for Epidermal Ultrastructure of Nostoc sphaeroides Kutzing under Scanning Electron Microscope

[Objective]The experiment aimed to explore a new way for observing surface structure of Nostoc sphaeroides Kutzing. [Method] The scanning electron microscope was used to observe the epidermal ultrastructure of wild and cultured Nostoc sphaeroides Kutzing. [ Result] The epidermis of wild and cultured Nostoc sphaeroides Kutzing showed mixture structure of fibril colloid which was reticular arranged. The difference between wild and cultured Nostoc sphaeroides Kutzing was that the outer epidermis of cultured Nostoc sphaeroides Kutzing had trichome distribution but the wild Nostoc sphaeroides Kutzing did not has such distribution. The obsevation results of under smaller than 10 μm by scanning electron microscope was touched thick and showed many folds and distortions. [ Conclusion] The scanning electron microscope was an effective way to study development of Nostoc sphaeroides Kutzing colony and it was worth popularizing.

Descriptions of the Immature Stages of Three Species of the Tribe Ozophorini (Heteroptera:Lygaeidae:Rhyparochrominae) from China

Immature stages of 3 species of the tribe Ozophorini from China are described for the first time, they are Bryanellocoris orientalis Hidaka (3rd^5th instars), Primierus longispinus Zheng (4th^5th instars) and Vertomannus brevicollum Zheng (4th^5th instars). Abrief study on fine structure of pale spots on head, pronotum and abdomen of 5th instar nymph of Bryanellocoris orientalis Hidaka was also given.

Investigation on the catalytic effects of AAEM during steam gasification and the resultant char reactivity in oxygen using Shengli lignite at different forms

The purpose of this study is to investigate the catalytic effects of alkali and alkaline earth metallic species （AAEM） on char conversion during the gasification in steam and the changes in ex-situ char reactivity in oxygen after the gasification in steam using different forms （i.e. H-form, Na-form） of Shengli brown coal. The surface area, AAEM concentration and carbon crystallite of chars were obtained to understand the change in char reactivity. It was found that not only Na concentration and carbon structure were the main factors governing the char reactivity in the atmosphere of steam and oxygen, but also they interacted each other. The presence of Na could facilitate the formation of disordering carbon structure in char, and the amorphous carbon structure would in turn affect the distribution of Na and thus its catalytic performance. The surface area and pore volume had very little relationship with the char＇s reactivity. Addi- tionally, the morphology of chars from different forms of coals were observed using scanning electron microscope （SEM）.

Effects of penehyclidine hydrochloride on rat intestinal barrier function during cardiopulmonary bypass

AIM:To test the ability of penehyclidine hydrochloride (PHC) to attenuate intestinal injury in a rat cardiopulmonary bypass (CPB) model.METHODS:Male Sprague-Dawley rats were randomly divided into six groups (eight each):sham-operated control;sham-operated low-dose PHC control (0.6 mg/kg);sham-operated high-dose PHC control (2.0 mg/kg);CPB vehicle control;CPB low-dose PHC (0.6 mg/kg);and CPB high-dose PHC (2.0 mg/kg).Blood samples were collected from the femoral artery 2 h after CPB for determination of plasma diamine oxidase (DAO),D-lactate and endotoxin levels.Spleen,liver,mesenteric lymph nodes and lung were removed for biochemical analyses.Intestinal tissue ultrastructure was examined by electron microscopy.RESULTS:In the sham-operated groups,high-and low-dose-PHC had no significant impact on the levels of DAO,D-lactate and endotoxin,or the incidence of intestinal bacterial translocation (BT).Serum levels of DAO,D-lactate,endotoxin and the incidence of intestinal BT were significantly increased in the surgical groups,compared with the sham-operated groups (0.543 ± 0.061,5.697 ± 0.272,14.75 ± 2.46,and 0/40 vs 1.038 ± 0.252,9.377 ± 0.769,60.37 ± 5.63,and 30/40,respectively,all P < 0.05).PHC alleviated the biochemical and histopathological changes in a dosedependent manner.Serum levels of DAO,D-lactate,and endotoxin and the incidence of intestinal BT in the high-dose PHC group were significantly lower than in the low-dose PHC group (0.637 ± 0.064,6.972 ± 0.349,29.64 ± 5.49,and 14/40 vs 0.998 ± 0.062,7.835 ± 0.330,38.56 ± 4.28,and 6/40,respectively,all P < 0.05).CONCLUSION:PHC protects the structure and function of the intestinal mucosa from injury after CPB in rats.

Hot deformation behavior and microstructure evolution of TC4 titanium alloy

The hot deformation behavior of Ti-6Al-4V （TC4） titanium alloy was investigated in the temperature range from 650℃ to 950℃ with the strain rate ranging from 7.7×10^-4 s^-1 to 7.7×10^-2 s^-1. The hot tension test results indicate that the flow stress decreases with increasing the deformation temperature and increases with increasing the strain rate. XRD analysis result reveals that only deformation temperature affects the phase constitution. The microstructure evolution under different deformation conditions was characterized by TEM observation. For the deformation of TC4 alloy, the work-hardening is dominant at low temperature, while the dynamic recovery and dynamic re-crystallization assisted softening is dominant at high temperature.

Two clinically relevant pressures of carbon dioxide pneumoperitoneum cause hepatic injury in a rabbit model

AIM:To observe the hepatic injury induced by carbon dioxide pneumoperitoneum(CDP) in rabbits,compare the eects olow-and high-pressure pneumoperitoneum,and to determine the degree o hepatic injury induced by these two clinically relevant CDP pressures.METHODS:Thirty healthy male New Zealand rabbits weighing 3.0 to 3.5 kg were randomly divided into three groups(n = 10 for each group) and subjected to the ollowing to CDP pressures:no gas control,10 mmHg,or 15 mmHg.Histological changes in liver tissues were observed with hematoxylin and eosin staining and transmission electron microscopy.Liver unction was evaluated using an automatic biochemical analyzer.Adenine nucleotide translocator(ANT) activity in liver tissue was detected with the atractyloside-inhibitor stop technique.Bax and Bcl-2 expression levels were detected bywestern blotting.RESULTS:Liver Functions in the 10 mmHg and 15 mmHg experimental groups were significantly disturbed compared with the control group.After CDP,the levels or alanine transaminase and aspartate transaminase were 77.3 ± 14.5 IU/L and 60.1 ± 11.4 IU/L,respectively,in the 10 mmHg experimental group and 165.1 ± 19.4 IU/L and 103.8 ± 12.3 IU/L,respectively,in the 15 mmHg experimental group,which were all higher than those of the control group(p < 0.05).There was no difference in pre-albumin concentration between the 10 mmHg experimental group and the control group,but the prealbumin level of the 15 mmHg experimental group was significantly lower than that of the control group(p < 0.05).No significant differences were observed in the levels of total bilirubin or albumin among the three groups.After 30 and 60 min of CDP,pH was reduced(p < 0.05) and fa CO2 was elevated(p < 0.05) in the 10 mmHg group compared with controls,and these changes were more pronounced in the 15 mmHg group.Hematoxylin and eosin staining showed no significant change in liver morphology,except for mild hyperemia in the two experimental groups.Transmission electron microscopy showed mild mitochondrial swelling in hepatocytes of the 10 mmHg group,and this was more pronounced in the 15 mmHg group.No significant difference in ANT levels was found between the control and 10 mmHg groups.However,ANT concentration was significantly lower in the 15 mmHg group compared with the control group.The expression of hepatic Bax was significantly increased in the two experimental groups compared with the controls,but there were no differences in Bcl-2 levels among the three groups.Twelve hours after CDP induction,the expression of hepatic Bax was more significant in the 15 mmHg group than in the 10 mmHg group.CONCLUSION:A CDP pressure of 15 mmHg caused more substantial hepatic injury,such as increased levels of acidosis,mitochondrial damage,and apoptosis;therefore,10 mmHg CDP is preferable for laparoscopic operations.

Process mineralogy and characteristic associations of iron and phosphorus-based minerals on oolitic hematite

The chemical compositions,mineralogical characteristics,as well as dissemination of iron-and phosphorus-based minerals were studied for the E’xi oolitic hematite from western Hubei Province in China by using chemical analysis,optical microscope,electron probe micro-analyzer(EPMA)and energy dispersive spectroscopy(EDS).It is found that this kind of oolitic hematite ore contains 47.71%TFe,10.96%SiO_2,as well as 0.874%P,with hematite as the dominant Fe-bearing minerals,and quartz,chamosite,illite and cellophane as main gangue minerals.The microscope examination showed that the ore has an oolitic structure,with some ooids principally formed by a series of concentric layers of hematite collophanite around nucleus that is hematite in the association with collophanite.Based on the EPMA and EDS analysis,it can be known that some ooids are primarily composed of hematite and collophanite.The separation can be achieved through fine grinding for those collophanite laminae with a higher P content.However,the dissemination of two minerals at the interface will result in the difficulty in effective separation.Besides,some ooids are made of chamosite with some nucleus formed of quartz,which is principally finely disseminated with hematite.In view of the close association and dissemination of iron-and phosphorus-based minerals in the ooids,it is found that the process of stage-grindings and stage-separations can be adopted to effectively increase the iron recovery and decrease the P content in the concentrate to some extent.

Improvement of cardiac function and reversal of gap junction remodeling by Neuregulin-1β in volume-overloaded rats with heart failure

Objective We performed experiments using Neuregulin-1β （NRG-1β） treatment to determine a mechanism for the protective role derived from its beneficial effects by remodeling gap junctions （GJs） during heart failure （HF）. Methods Rat models of I-IF were established by aortocaval fistula. Forty-eight rats were divided randomly into the HF （HF, n = 16）, NRG-1β trealanent （NRG, n = 16）, and sham operation （S, n = 16） group. The rats in the NRG group were administered NRG-1β （10 μg/kg per day） for 7 days via the tail vein, whereas the other groups were injected with the same doses of saline, Twelve weeks after operation, Connexin 43 （Cx43） expression in single myocytes obtained from the left ventricle was determined by immunocytochemistry. Total protein was extracted from frozen left ventricular tissues for immunoblotting assay, and the ultrastmcture of myocytes was observed by transmission electron microscopy. Results Compared with the HF group, the cardiac fimction of rats in the NRG group was markedly improved, irregular distribution and deceased Cx43 expression were relieved. The ultrastmcture of myocytes was seriously damaged in HF rats, and NRG-1β reduced these pathological damages. Conclusions Short-term NRG-1β treatment can rescue pump failure in experimental models of volume overload-induced HF, which is related to the recovery of GJs structure and the improvement of Cx43 expression.

occurrence and microscopic analyses of multicellular magnetotactic prokaryotes from coastal sediments in the Yellow Sea

Multicellular magnetotactic prokaryotes （MMPs） are a group of aggregates composed of 7-45 gram-negative cells synthesizing intracellular magnetic crystals. Although they are thought to be globally distributed, MMPs have been observed only in marine environments in America and Europe. Most MMPs share a rosette-like morphology and biomineralize iron sulfide crystals. In the present study, abundant MMPs were observed, with a density of 26 ind./cm^3, in the sediments of a coastal lagoon, Lake Yuehu, in the Yellow Sea. Optical microscopy showed that all of them were rosette shaped with a diameter of 5.5±0.8 μm. Transmission electron microscopy revealed that these MMPs were composed of 10- 16 ovoid cells and flagellated peritrichously. High-resolution transmission electron microscopy and energy dispersive X-ray analysis indicated that they biomineralized bullet-shaped magnetite crystals in highly organized parallel chains within which the magnetosomes were oriented in the same direction. This is the first report of MMPs from Asia and demonstrates the ubiquitous distribution of MMPs.

Preparation of Ti/PTFE-F-PbO2 Electrode with a Long Life from the Sulfamic Acid Bath and Its Application in Organic Degradation

A polytetrafluoroethylene （PTFE）-doped PbO2 electrode on a Ti substrate was prepared by galvanostatic method from the sulfamic acid bath （Ti/PTFE-F-PbO2-I） or nitric acid bath （Ti/PTFE-F-PbO2-II）. Scanning Electron Microscopy revealed that the Ti/PTFE-PbO2-I electrode had a more regular morphology with smaller size crystals than the Ti/PTFE-F-PbO2-II electrode. On the basis of the results of both the accelerated electrolysis test and the empirical formula for estimating the service life of an electrode, the service life of the Ti/PTFE-PbO2-I electrode was predicted to be more than 7 years under conventional electrolysis conditions （0.1 A·cm^-2）. During the treatment of 4-chlorophenol-contaminated water, the Ti/PTFE-PbO2-I anode showed both a good electro-catalytic activity and high electrochemical stability, exhibiting an excellent potential application.

Effect of ultrasonic field on microstructure and mechanical properties of as-cast 7085 aluminum alloy

The effect of an ultrasonic field on the microstructure and mechanical properties of 7085 aluminum alloy during solidification was investigated by optical microscopy, Vickers hardness test, tensile test, scanning electron microscopy （SEM） with energy dispersive X-ray spectrometry, and electron probe micro-analysis （EPMA）. The results showed that the grains of aluminum alloy were significantly refined and secondary phases were dispersed and distributed uniformly at the grain boundaries, due to ultrasonic treatment （UST）. By EPMA, it was observed that the distribution of the main elements A1, Zn, Mg and Cu was more homogeneous in alloys with UST, than in alloys without UST. The mechanical properties of the aluminum alloy also significantly improved. As demonstrated by the SEM fractography of the fractured faces of several castings, fracture of the unrefined specimens occurred in a brittle manner, whereas the cracks of the refined specimens showed quasi-cleavage fracture.

Intrahepatic transplantation of hepatic oval cells for fulminant hepatic failure in rats

AIM： To evaluate the effect of intrahepatic transplantation of hepatic oval cells （HOC） on fulminant hepatic failure （FHF） in rats.METHODS： HOC obtained from rats were labeled with green fluocescent protein （GFP） or 5, 6- carboxyfluorescein diacetate succinmidyl ester （CFDASE）. Cell fluorescence was observed under fluorescent microscope at 6, 24, 48 and 72 h after labeling. CFDA- SE labeled HOC （5 × 10^6 cells each rat） were injected into livers of rats with FHF induced by D-galactosamine. Serum albumin （ALB）, alanine aminotransferase （ALT）, aspartate aminotransferase （AST） and total bilirubin （TBil） levels were measured at different time points. Liver function of rats was examined on days 3, 7, 14 and 21 after HOC transplantation.RESULTS： The positive rate of GFP and CFDA-SE labeled HOC was 10% and 90%, respectively, with no significant change in cell viabilities. The survival rate was higher in HOC transplantation group than in control group, especially 48 （9/15 vs 6/15） and 72 h （9/15 vs 4/15） after HOC transplantation. The serum ALT, AST and TBil levels were decreased while the serum AIb level was increased after HOC transplantation. Fluorescence became faded and diffused in liver tissues, suggesting that proliferation and differentiation occur in transplanted HOC.CONCLUSION： CFDA-SE is superior to GFP in labeling HOC, although fluorescence intensity is decreased progressively with cell division. HOC transplantation can improve the liver function and increase the survival rate of recipients.