The recrystallization nucleation processes of two cold-rolled Al-Mg-Si/SiCpcomposites with different contents of Mg are investigated mainly by dynamic mechanical analyzer (DMA) and electron microscopy including high...The recrystallization nucleation processes of two cold-rolled Al-Mg-Si/SiCpcomposites with different contents of Mg are investigated mainly by dynamic mechanical analyzer (DMA) and electron microscopy including high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) andhigh-resolution transmission electron microscopy (HRTEM). Internal friction and electron microscopy results show that solute atom clusters are present in association with dislocationsin supersaturated cold-rolled composites. During recrystallization process, the internal friction peak position of Al-Mg-Si/3SiCp/2Mg (volume fraction,%) is higher than that of Al-Mg-Si/3SiCp(volume fraction,%) due to more solute atom clusters formed in association with the dislocations in the cold-rolled composite with a much higher Mg content, indicating a strongerresistance for the recrystallization nucleation.展开更多
AIM: To investigate the expression of Cyclooxygenase-2 (COX-2), proliferating cell nuclear antigen (PCNA), Ki-67 and p53 in gastrointestinal stromal tumors (GISTs) and its relationship with histopathological parameter...AIM: To investigate the expression of Cyclooxygenase-2 (COX-2), proliferating cell nuclear antigen (PCNA), Ki-67 and p53 in gastrointestinal stromal tumors (GISTs) and its relationship with histopathological parameters. METHODS: Twenty-five GISTs were examined by light microscopy and immunohistochemistry. c-kit, CD34, SMA, S-100 protein, COX-2, PCNA, Ki-67 and p53 were detected immunohistochemically and the relationship was evaluated among histopathologic parameters such as mitotic index (MI), tumor grade, tumor size, COX-2, PCNA, Ki-67 and p53. RESULTS: COX-2 protein expression was found in 19 of 25 (76%) of the tumors, and expression was noted in the cytoplasm of the tumor cells. p53 was significantly related to MI and tumor grade but no relationship was found between COX-2, proliferation markers and MI, tumor grade and tumor size. CONCLUSION: COX-2 is expressed in most GISTs and it may play an important role in the proliferation and progression of these tumors or a useful marker to identify GIST. Although immunohistochemical assessment of p53 can be used for distinguishing the risk groups of GISTs, tumor size and mitotic rate should be considered at the same time.展开更多
AIM:To investigate the distribution of the placental form of glutathione-S-transferase (GST) in colon polyps in order to evaluate the role of GST-pi in these tissues. METHODS: Sixteen polyp tissues removed at colonosc...AIM:To investigate the distribution of the placental form of glutathione-S-transferase (GST) in colon polyps in order to evaluate the role of GST-pi in these tissues. METHODS: Sixteen polyp tissues removed at colonoscopy were examined. Tissues were investigated histologically and ultrastructurally. GST-pi expression was also analysed immunohistochemically, using peroxidase anti-peroxidase (PAP) method and immunogold labelling method, for light and electron microscope respectively. RESULTS: All polyp tissues examined were adenoma of low, mild and high-grade dysplasia as shown in the histopathological reports. Nevertheless, the examination of the above specimens with electron microscope revealed that 3 of 9 adenoma of mild dysplasia had ultrastuctural features similar to high-grade dysplasia adenoma. GST-pi was variably expressed in adenoma, with the lowest relative levels occurring in low-gradeadenoma and the highest levels found in high-grade adenoma. GST-pi was located mainly in undifferentiated epithelial cells. GST-pi positive particles were found in the cytoplasm and especially in the nucleus adjacent to the nuclear membrane of these cells. CONCLUSION:The overexpression of GST-pi in mildgrade adenomas with significant subcellular changes and in the majority of high-grade dysplasia adenoma suggests that this might be related to the carcinogenetic proceeding. Immunohistochemical localization of GST-pi in combination with ultrastructural changes indicate that GST-pi might be a sensitive agent for the detection of preneoplastic transformations in adenoma.展开更多
Plasma electrolytic oxidation(PEO) was developed as a bond coat for air plasma sprayed(APS) nanostructure ZrO2 as top coat to enhance the corrosion resistance and antibacterial activity of Mg alloy. Corrosion beha...Plasma electrolytic oxidation(PEO) was developed as a bond coat for air plasma sprayed(APS) nanostructure ZrO2 as top coat to enhance the corrosion resistance and antibacterial activity of Mg alloy. Corrosion behavior and antibacterial activities of coated and uncoated samples were assessed by electrochemical tests and agar diffusion method toward Escherichia coli(E. coli) bacterial pathogens, respectively. The lowest corrosion current density and the highest charge transfer resistance, phase angle and impedance modulus were observed for PEO/nano-ZrO2 coated sample compared with those of PEO coated and bare Mg alloys. Nano-ZrO2 top coat which has completely sealed PEO bond coat is able to considerably delay aggressive ions transportation towards Mg alloy surface and significantly enhances corrosion resistance of Mg alloy in simulated body fluid(SBF) solution. Moreover, higher antibacterial activity was also observed in PEO/nano-ZrO2 coating against bacterial strains than that of the PEO coated and bare Mg alloys. This observation was attributed to the presence of ZrO2 nanoparticles which decelerate E. coli growth as a result of E. coli membranes.展开更多
A high speed steel composite roll billet was fabricated, which is regular in shape, smooth in surface, slight in trace, compact in internal structure, free of slag inclusion, shrinkage cavity, cracks and other flaws, ...A high speed steel composite roll billet was fabricated, which is regular in shape, smooth in surface, slight in trace, compact in internal structure, free of slag inclusion, shrinkage cavity, cracks and other flaws, and good in macro quality of junction surface using a vertical continuous casting machine. The interface zone microstructure of bimetallic in billet of high speed steel composite roll was analyzed by metallurgical microscope(OM), X-ray diffractmeter(XRD), scanning electron microscopy(SEM) and energy-dispersive X-ray analysis(EDS). The results indicate that the microstructure of roll billet is composed of chilled solidified layer, dendrite zone, interfacial zone of bimetal and core material zone. The microstructure of outer shell material is composed of martensite + bainite + residual austenite + some small labyrinth-shape, small-short lath-shape, or dollop-shape eutectic carbides. The microstructure of core material is slice-shape pearlite and a little ferrite along boundary of cells. The interface region microstructure of bimetallic composite roll consists of diffusion region, chilled solidified layer and columnar grain region.展开更多
Objective To investigate the effect of emodin on lipopolysaccharides (LPS)-induced corneal injury in rats. Methods Three parallel incisions on the central surface of corneal epithelium were made and LPS was applied...Objective To investigate the effect of emodin on lipopolysaccharides (LPS)-induced corneal injury in rats. Methods Three parallel incisions on the central surface of corneal epithelium were made and LPS was applied on them to induce corneal injury in Wistar rats. All rats were randomly divided into emodin group (n=40) and keratitis group (n=40). Rats in the emodin group received subconjunctival injection of emodin and rats in the keratitis group received its vehicle 30 minutes before LPS exposure. At different time points-1 3, 6, 12, and 24 hours after LPS exposure, the symptoms of all rats were observed and the severity of their ocular inflammation was examined with a slit lamp microscope, then 8 rats in each group were killed through cervical dislocation and their eyes were enucleated and prepared to observe pathological changes of corneal tissue under a light microscope. The activation of nuclear factor-loB (NF-κB) under different condi- tions was determined by Western blot. Immunocytochemistry staining with an antibody against intercellular adhesion molecule-1 (ICAM-1) was performed to identify positive cells in corneal tissues. Results The model of acute keratitis was successfully established in Wistar rats. LPS could induce a typical corneal inflammatory response, such as hyperemia, corneal edema and opacity, which were observed in model rats. Compared with keratitis group, both ocular behaviors and damages of the corneal structure were improved in emodin group. Furthermore, the activation of NF-κB and the expression of ICAM-1 induced by LPS were markedly inhibited in emodin group. Conclusion Emodin can inhibit the activation of NF-κB and the expression of ICAM-I induced by LPS in corneas, protect against acute corneal injury, and improve symptoms in rats.展开更多
AIM: To evaluate the effect of double-balloon enteros- copy (DBE) on pancreas histology and levels of pancre- atic enzymes. METHODS: Conventional upper gastrointestinal endos- copy was performed on five control pi...AIM: To evaluate the effect of double-balloon enteros- copy (DBE) on pancreas histology and levels of pancre- atic enzymes. METHODS: Conventional upper gastrointestinal endos- copy was performed on five control pigs. Oral DBE was performed with an EN-450T5 enteroscope on 20 pigs. Two experimental groups (10 pigs each) were defined according to DBE duration: 90 rain for Group 1 and 140 min for Group 2. During oral insertion, the balloons were not inflated in the descending part of the duodenum to avoid the minor duodenal papilla. Serum amy- lase, lipase and C-reactive protein (CRP) levels were monitored before the procedure and repeated every 30 min until the exploration was finished, as well as 24 h and 7 d after. After the procedure and for a total of 7 d, the pigs were observed twice a day for signs of de- creased activity, irritability, vomiting or anorexia. Gross and microscopic examination of the pancreas was per- formed on day 7. RESULTS: All animals tolerated DBE without clini- cal manifestations of acute pancreatitis. Experimental groups had higher levels of enzymes than the control group at 24 h. Throughout the exploration, the amylase levels increased significantly above the baseline 24 h after DBE, although the increase was not statistically significant and did not reach 20% of the baseline. An increase in lipase and CRP was observed at 24 h after the procedure, although by day 7, all enzymatic lev- els had returned to baseline. No differences between Groups 1 and 2 were found for any enzyme and sam- pling site during and after the procedure. Similarly, no correlation between insertion depth and enzyme levels was observed. Direct in situ and post-removal inspec- tion of the pancreas did not show any evidence of fluid collection, abscesses or hemorrhage. Histological examination of the pancreas from Groups 1 and 2 re- vealed the existence of focal areas (0.14-0.26 mm2) of ischemic necrosis in 47.4% of the animals. In the pigs with damaged pancreas, the left lobe (tail) was always affected. However, this only happened in 83.3% of the samples from the right lobe (head) and in 33.3% of the samples from the body of the pancreas. Significant differences were found between the left lobe (tail) and the body for the percentage of affected pancreas. Both the size of the lesions and the percentage of affected pancreas were higher in the left pancreatic lobe (tail). The presence of the lesions was not related to the ex- ploration length.CONCLUSION: The increase in pancreatic enzymes after DBE could be related to focal points of pancreatic ischemic necrosis due to mechanical stress.展开更多
The secretion function of mantle is closely related to shell formation in some bivalves and gastropods. Up to now, few researches have been reported for cuttlebone formation in the class Cephalopoda. In this study, th...The secretion function of mantle is closely related to shell formation in some bivalves and gastropods. Up to now, few researches have been reported for cuttlebone formation in the class Cephalopoda. In this study, the structure and secretion function of cuttlebone sac of the golden cuttlefish Sepia esculenta was analyzed using the histological and histochemical methods. The results showed that high and columnar cells located in sac epithelium, and fiat cells existed near the base membrane. A lot of fibroblasts were found in the lateral mantle collective tissue. Some mucus, mucopolysaccharide and alkaline phosphatase (ALP) were found in the sac. The ultrastructural characteristics of Quasi-connective-tissue-calcium cells (QCTCC) were observed using a transmission electron microscope (TEM). The relationship between cuttlebone sac secretion function and shell formation was discussed.展开更多
The influence of a novel three-step aging on strength, stress corrosion cracking(SCC) and microstructure of AA7085 was investigated by tensile testing and slow strain rate testing combined with transmission electron m...The influence of a novel three-step aging on strength, stress corrosion cracking(SCC) and microstructure of AA7085 was investigated by tensile testing and slow strain rate testing combined with transmission electron microscopy(TEM). The results indicate that with the increase of second-step aging time of two-step aging, the mechanical properties increase first and then decrease, while the SCC resistance increases. Compared with two-step aging, three-step aging treatment improves SCC resistance and the strength increases by about 5%. The effects of novel three-step aging on strength and SCC resistance are explained by the role of matrix precipitates and grain boundary precipitates, respectively.展开更多
Purpose: To study in situ the intraocular position of iris-claw phakic intraocular lens (ICPIOL) in myopic eyes using ultrasound biomicroscopy (UBM). Methods: UBM echograms of the anterior segment were taken preoperat...Purpose: To study in situ the intraocular position of iris-claw phakic intraocular lens (ICPIOL) in myopic eyes using ultrasound biomicroscopy (UBM). Methods: UBM echograms of the anterior segment were taken preoperatively and 62 to 115 days postoperatively in 6 eyes implanted with the Verisys ICPIOL (AMO). The echograms were assessed for the effect of the ICPIOL on iris tissue. Results: The preoperative distance between the corneal endothelium and the lens ranged from 2.96 to 3.09 mm, and the postoperative distance between the ICPIOL and the corneal endothelium, from 1.86 to 2.03 mm. The distance between the lens and the posterior surface of the ICPIOL ranged from 0.61 to 0.76 mm. The distance between the superior, inferior optic edge and the iris ranged from 0.49 to 1.00 mm, 0.21 to 0.51 mm respectively. The shortest distance between the ICPIOL haptics and the angle of anterior chamber ranged from 1.25 to 1.65 mm. The indentation of iris tissue by the ICPIOL haptics without pigmentary dispersion and distortion of posterior curvature of iris was observed. Conclusion : Adequate space is maintained between the Verisyse myopic ICPIOL and the corneal endothelium, angle, and crystalline lens. Haptic indentation of the iris without pigment erosion and distortion of iris curvature is noted. The ICPIOL implanted in phakic eyes is a safe alternative for treatment of high myopia.展开更多
A novel solid support adsorbent for CO2capture was developed by loading pentaethylenehexamine(PEHA)on commercially available mesoporous molecular sieve MCM-41 using wet impregnation method.MCM-41 samples before and af...A novel solid support adsorbent for CO2capture was developed by loading pentaethylenehexamine(PEHA)on commercially available mesoporous molecular sieve MCM-41 using wet impregnation method.MCM-41 samples before and after PEHA loading were characterized by X-ray powder diffraction,N2adsorption/desorption,thermal gravimetric analysis and scanning electron microscope to investigate the textural and thermo-physical properties.CO2adsorption performance was evaluated in a fixed bed adsorption system.Results indicated that the structure of MCM-41 was preserved after loading PEHA.Surface area and total pore volume of PEHA loaded MCM-41 decreased with the increase of loading.The working adsorption capacity of CO2could be significantly improved at 60%of PEHA loading and 75°C.The effect of the height of adsorbent bed was investigated and the best working adsorption capacity for MCM-41-PEHA-60 reached 165 mg·(g adsorbent)-1at 75°C.Adsorption/desorption circle showed that the CO2working adsorption capacity of MCM-41-PEHA kept stable.展开更多
The initiation sites and influencing factors of cavity nucleation were investigated for a Ti-6Al-2Zr-1Mo-1V alloy with lamellar starting structure,using the isothermal hot compression test.All samples were deformed to...The initiation sites and influencing factors of cavity nucleation were investigated for a Ti-6Al-2Zr-1Mo-1V alloy with lamellar starting structure,using the isothermal hot compression test.All samples were deformed to a true strain of 0.70 in the temperature range of 750-950°C and strain rate range of 0.001-10 s-1.The corresponding microstructures were observed by means of the metallurgical microscopy and scanning electron microscopy(SEM).It was found that all cavities occurred at the bulge regions of the compression specimens.Most of cavities nucleated along prior beta boundaries oriented 45°to the compression axis,while others nucleated at the interfaces of lamellar alpha colonies.Cavity nucleation was inhibited with increasing the volume fraction of beta phase and the volume fraction spheroidized of lamellar alpha phase.展开更多
The effect of thixoforming process on morphologies of silicon particles that affect fracture mode of A356 alloy was investigated.Microstructure and fracture surfaces of thixoformed samples were investigated by image a...The effect of thixoforming process on morphologies of silicon particles that affect fracture mode of A356 alloy was investigated.Microstructure and fracture surfaces of thixoformed samples were investigated by image analyzing technique and scanning electron microscopy.A new combination parameter, called silicon density ratio (SDR) index, was introduced.SDR index approximates the collective effects of morphological characteristics of silicon particles on microstructure transparency of alloy in crossing the dislocation.It is suggested that samples with lower SDR index have superior mechanical properties, especially elongation, and consequently intergranular fracture mode.On the contrary, samples with higher SDR index have inferior mechanical properties and fracture path tends to propagate along the cell boundaries leading to transgranular fracture.展开更多
The presence of sperm was observed in different organs of the reproductive tract of M. schmitti. These were the club, baffle and terminal zone of the oviducal gland, posterior portion of the uterus and in the cervix. ...The presence of sperm was observed in different organs of the reproductive tract of M. schmitti. These were the club, baffle and terminal zone of the oviducal gland, posterior portion of the uterus and in the cervix. This fact allowed for consideration not only its storage but its interaction with the female reproductive tract epithelia as well. SEM (microscopic observation studies) detected loose and sole spermatozoa in the club and baffle zones in a pregnant female. On the other hand, histochemical techniques showed sperm storage tubules of the terminal zone, which contain bundles of sperm, do not stain AB (alcian blue) or PAS (periodic acid schiff). Disintegration of some of the male gametes was observed in the posterior part of the uterus with TEM (transmission electron microscopy) studies which would indicate a first uterine sperm selection. The uterine epithelial cells involved in this process showed an important level of secretion vacuoles suggesting an interaction with sperm cells. Sperm in the cervix was found without the matrix that constitutes the spermatozeugmata formed in the male tract. Some heads of the sperm were uncurled while they were interacting with the cervical cells.展开更多
Mg-1.5Zn-0.2Zr-xCe (x=0, 0.1, 0.3, 0.5, mass fraction, %) alloys were prepared by conventional semi-continuous casting. The effect of rare earth Ce on the microstructure of Mg-1.5Zn-0.2Zr-xCe alloys was studied and th...Mg-1.5Zn-0.2Zr-xCe (x=0, 0.1, 0.3, 0.5, mass fraction, %) alloys were prepared by conventional semi-continuous casting. The effect of rare earth Ce on the microstructure of Mg-1.5Zn-0.2Zr-xCe alloys was studied and the distribution of Ce was analyzed by optical microscopy (OM), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results indicate that Ce element exists in the form of Mg12Ce phase and has an obvious refining effect on the microstructure of test alloys. As the Ce content increases, the grain size reduces, the grain boundaries turn thinner, and the distribution of Mg12Ce precipitates becomes more and more dispersed. The Mg-1.5Zn-0.2Zr alloy with 0.3%Ce has the best refinement effect. From center to periphery of the ingot, the amount of granular precipitates in the grain reduces. In longitudinal section of the ingot, some relative long columnar grains appear.展开更多
Anatomical structure of differently originated seed envelopes in one-seeded indehiscent fruits of Urticaceae and Asteraceae members is studied using light and scanning electron microscopes. It was found that in anthoc...Anatomical structure of differently originated seed envelopes in one-seeded indehiscent fruits of Urticaceae and Asteraceae members is studied using light and scanning electron microscopes. It was found that in anthocarps and involucrate fruits of both families the relations between the primary (pericarp) and secondary fruit envelopes (perianth and/or involucre) were composed under complexification (union) type, and not as substitution. Numerous examples of non-homologous resemblance in fruit envelope structure indicate a high degree of adaptability of certain histological types, recurring on a different morphological basis in different phyletic lines within a family. These tissue complexes represent widely occurring types of the pericarp (Utricaceae) or pericarp and seed coat tissue union (Asteraceae). This evolutionary repetition or pseudocyclic resemblance is apparently another common regularity of one-seeded indehiscent fruits evolution in addition to those enumerated in general by Zohary (1950).展开更多
基金Project(LH201236)supported by the Pre-research Project of Equipment Development Department of China
文摘The recrystallization nucleation processes of two cold-rolled Al-Mg-Si/SiCpcomposites with different contents of Mg are investigated mainly by dynamic mechanical analyzer (DMA) and electron microscopy including high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) andhigh-resolution transmission electron microscopy (HRTEM). Internal friction and electron microscopy results show that solute atom clusters are present in association with dislocationsin supersaturated cold-rolled composites. During recrystallization process, the internal friction peak position of Al-Mg-Si/3SiCp/2Mg (volume fraction,%) is higher than that of Al-Mg-Si/3SiCp(volume fraction,%) due to more solute atom clusters formed in association with the dislocations in the cold-rolled composite with a much higher Mg content, indicating a strongerresistance for the recrystallization nucleation.
文摘AIM: To investigate the expression of Cyclooxygenase-2 (COX-2), proliferating cell nuclear antigen (PCNA), Ki-67 and p53 in gastrointestinal stromal tumors (GISTs) and its relationship with histopathological parameters. METHODS: Twenty-five GISTs were examined by light microscopy and immunohistochemistry. c-kit, CD34, SMA, S-100 protein, COX-2, PCNA, Ki-67 and p53 were detected immunohistochemically and the relationship was evaluated among histopathologic parameters such as mitotic index (MI), tumor grade, tumor size, COX-2, PCNA, Ki-67 and p53. RESULTS: COX-2 protein expression was found in 19 of 25 (76%) of the tumors, and expression was noted in the cytoplasm of the tumor cells. p53 was significantly related to MI and tumor grade but no relationship was found between COX-2, proliferation markers and MI, tumor grade and tumor size. CONCLUSION: COX-2 is expressed in most GISTs and it may play an important role in the proliferation and progression of these tumors or a useful marker to identify GIST. Although immunohistochemical assessment of p53 can be used for distinguishing the risk groups of GISTs, tumor size and mitotic rate should be considered at the same time.
文摘AIM:To investigate the distribution of the placental form of glutathione-S-transferase (GST) in colon polyps in order to evaluate the role of GST-pi in these tissues. METHODS: Sixteen polyp tissues removed at colonoscopy were examined. Tissues were investigated histologically and ultrastructurally. GST-pi expression was also analysed immunohistochemically, using peroxidase anti-peroxidase (PAP) method and immunogold labelling method, for light and electron microscope respectively. RESULTS: All polyp tissues examined were adenoma of low, mild and high-grade dysplasia as shown in the histopathological reports. Nevertheless, the examination of the above specimens with electron microscope revealed that 3 of 9 adenoma of mild dysplasia had ultrastuctural features similar to high-grade dysplasia adenoma. GST-pi was variably expressed in adenoma, with the lowest relative levels occurring in low-gradeadenoma and the highest levels found in high-grade adenoma. GST-pi was located mainly in undifferentiated epithelial cells. GST-pi positive particles were found in the cytoplasm and especially in the nucleus adjacent to the nuclear membrane of these cells. CONCLUSION:The overexpression of GST-pi in mildgrade adenomas with significant subcellular changes and in the majority of high-grade dysplasia adenoma suggests that this might be related to the carcinogenetic proceeding. Immunohistochemical localization of GST-pi in combination with ultrastructural changes indicate that GST-pi might be a sensitive agent for the detection of preneoplastic transformations in adenoma.
基金the Universiti Teknologi Malaysia (UTM) for providing research facilities and financial support under Grants No:(1)UTM-Research University Grant (RUG) (Q.J130000.2524.16H35),and (2)Nippon Sheet Glass (NSG) R.J130000.7324.4B300
文摘Plasma electrolytic oxidation(PEO) was developed as a bond coat for air plasma sprayed(APS) nanostructure ZrO2 as top coat to enhance the corrosion resistance and antibacterial activity of Mg alloy. Corrosion behavior and antibacterial activities of coated and uncoated samples were assessed by electrochemical tests and agar diffusion method toward Escherichia coli(E. coli) bacterial pathogens, respectively. The lowest corrosion current density and the highest charge transfer resistance, phase angle and impedance modulus were observed for PEO/nano-ZrO2 coated sample compared with those of PEO coated and bare Mg alloys. Nano-ZrO2 top coat which has completely sealed PEO bond coat is able to considerably delay aggressive ions transportation towards Mg alloy surface and significantly enhances corrosion resistance of Mg alloy in simulated body fluid(SBF) solution. Moreover, higher antibacterial activity was also observed in PEO/nano-ZrO2 coating against bacterial strains than that of the PEO coated and bare Mg alloys. This observation was attributed to the presence of ZrO2 nanoparticles which decelerate E. coli growth as a result of E. coli membranes.
基金Project(200809123) supported by the National Natural Science Foundation of China
文摘A high speed steel composite roll billet was fabricated, which is regular in shape, smooth in surface, slight in trace, compact in internal structure, free of slag inclusion, shrinkage cavity, cracks and other flaws, and good in macro quality of junction surface using a vertical continuous casting machine. The interface zone microstructure of bimetallic in billet of high speed steel composite roll was analyzed by metallurgical microscope(OM), X-ray diffractmeter(XRD), scanning electron microscopy(SEM) and energy-dispersive X-ray analysis(EDS). The results indicate that the microstructure of roll billet is composed of chilled solidified layer, dendrite zone, interfacial zone of bimetal and core material zone. The microstructure of outer shell material is composed of martensite + bainite + residual austenite + some small labyrinth-shape, small-short lath-shape, or dollop-shape eutectic carbides. The microstructure of core material is slice-shape pearlite and a little ferrite along boundary of cells. The interface region microstructure of bimetallic composite roll consists of diffusion region, chilled solidified layer and columnar grain region.
基金Supported by Technology Foundation of Shandong Education Department (J08LH59)
文摘Objective To investigate the effect of emodin on lipopolysaccharides (LPS)-induced corneal injury in rats. Methods Three parallel incisions on the central surface of corneal epithelium were made and LPS was applied on them to induce corneal injury in Wistar rats. All rats were randomly divided into emodin group (n=40) and keratitis group (n=40). Rats in the emodin group received subconjunctival injection of emodin and rats in the keratitis group received its vehicle 30 minutes before LPS exposure. At different time points-1 3, 6, 12, and 24 hours after LPS exposure, the symptoms of all rats were observed and the severity of their ocular inflammation was examined with a slit lamp microscope, then 8 rats in each group were killed through cervical dislocation and their eyes were enucleated and prepared to observe pathological changes of corneal tissue under a light microscope. The activation of nuclear factor-loB (NF-κB) under different condi- tions was determined by Western blot. Immunocytochemistry staining with an antibody against intercellular adhesion molecule-1 (ICAM-1) was performed to identify positive cells in corneal tissues. Results The model of acute keratitis was successfully established in Wistar rats. LPS could induce a typical corneal inflammatory response, such as hyperemia, corneal edema and opacity, which were observed in model rats. Compared with keratitis group, both ocular behaviors and damages of the corneal structure were improved in emodin group. Furthermore, the activation of NF-κB and the expression of ICAM-1 induced by LPS were markedly inhibited in emodin group. Conclusion Emodin can inhibit the activation of NF-κB and the expression of ICAM-I induced by LPS in corneas, protect against acute corneal injury, and improve symptoms in rats.
基金Supported by PI070712 Project (Instituto de Salud Carlos Ⅲ, Ministerio de Sandiady Consumo, Spain)BIO-MED07/08-0019 Project (Consejería de Educación, Cienciae Investigación de la Región de Murcia, Spain)
文摘AIM: To evaluate the effect of double-balloon enteros- copy (DBE) on pancreas histology and levels of pancre- atic enzymes. METHODS: Conventional upper gastrointestinal endos- copy was performed on five control pigs. Oral DBE was performed with an EN-450T5 enteroscope on 20 pigs. Two experimental groups (10 pigs each) were defined according to DBE duration: 90 rain for Group 1 and 140 min for Group 2. During oral insertion, the balloons were not inflated in the descending part of the duodenum to avoid the minor duodenal papilla. Serum amy- lase, lipase and C-reactive protein (CRP) levels were monitored before the procedure and repeated every 30 min until the exploration was finished, as well as 24 h and 7 d after. After the procedure and for a total of 7 d, the pigs were observed twice a day for signs of de- creased activity, irritability, vomiting or anorexia. Gross and microscopic examination of the pancreas was per- formed on day 7. RESULTS: All animals tolerated DBE without clini- cal manifestations of acute pancreatitis. Experimental groups had higher levels of enzymes than the control group at 24 h. Throughout the exploration, the amylase levels increased significantly above the baseline 24 h after DBE, although the increase was not statistically significant and did not reach 20% of the baseline. An increase in lipase and CRP was observed at 24 h after the procedure, although by day 7, all enzymatic lev- els had returned to baseline. No differences between Groups 1 and 2 were found for any enzyme and sam- pling site during and after the procedure. Similarly, no correlation between insertion depth and enzyme levels was observed. Direct in situ and post-removal inspec- tion of the pancreas did not show any evidence of fluid collection, abscesses or hemorrhage. Histological examination of the pancreas from Groups 1 and 2 re- vealed the existence of focal areas (0.14-0.26 mm2) of ischemic necrosis in 47.4% of the animals. In the pigs with damaged pancreas, the left lobe (tail) was always affected. However, this only happened in 83.3% of the samples from the right lobe (head) and in 33.3% of the samples from the body of the pancreas. Significant differences were found between the left lobe (tail) and the body for the percentage of affected pancreas. Both the size of the lesions and the percentage of affected pancreas were higher in the left pancreatic lobe (tail). The presence of the lesions was not related to the ex- ploration length.CONCLUSION: The increase in pancreatic enzymes after DBE could be related to focal points of pancreatic ischemic necrosis due to mechanical stress.
基金This study was supported by the grants from the National Natural Science Foundation of China (No. 30600463)the Key Laboratory of Mariculture of Ministry of Education, 0cean University of China (No. 200610).
文摘The secretion function of mantle is closely related to shell formation in some bivalves and gastropods. Up to now, few researches have been reported for cuttlebone formation in the class Cephalopoda. In this study, the structure and secretion function of cuttlebone sac of the golden cuttlefish Sepia esculenta was analyzed using the histological and histochemical methods. The results showed that high and columnar cells located in sac epithelium, and fiat cells existed near the base membrane. A lot of fibroblasts were found in the lateral mantle collective tissue. Some mucus, mucopolysaccharide and alkaline phosphatase (ALP) were found in the sac. The ultrastructural characteristics of Quasi-connective-tissue-calcium cells (QCTCC) were observed using a transmission electron microscope (TEM). The relationship between cuttlebone sac secretion function and shell formation was discussed.
基金Project(2012CB619502)supported by the National Basic Research Program of ChinaProject(2016YFB0300800)supported by the National Key Research and Development Program of China+1 种基金Project(CALT201507)supported by the CALT Research Innovation Partnership Fund,ChinaProject(HPCM-201403)supported by the State Key Laboratory of High Performance Complex Manufacturing,China
文摘The influence of a novel three-step aging on strength, stress corrosion cracking(SCC) and microstructure of AA7085 was investigated by tensile testing and slow strain rate testing combined with transmission electron microscopy(TEM). The results indicate that with the increase of second-step aging time of two-step aging, the mechanical properties increase first and then decrease, while the SCC resistance increases. Compared with two-step aging, three-step aging treatment improves SCC resistance and the strength increases by about 5%. The effects of novel three-step aging on strength and SCC resistance are explained by the role of matrix precipitates and grain boundary precipitates, respectively.
文摘Purpose: To study in situ the intraocular position of iris-claw phakic intraocular lens (ICPIOL) in myopic eyes using ultrasound biomicroscopy (UBM). Methods: UBM echograms of the anterior segment were taken preoperatively and 62 to 115 days postoperatively in 6 eyes implanted with the Verisys ICPIOL (AMO). The echograms were assessed for the effect of the ICPIOL on iris tissue. Results: The preoperative distance between the corneal endothelium and the lens ranged from 2.96 to 3.09 mm, and the postoperative distance between the ICPIOL and the corneal endothelium, from 1.86 to 2.03 mm. The distance between the lens and the posterior surface of the ICPIOL ranged from 0.61 to 0.76 mm. The distance between the superior, inferior optic edge and the iris ranged from 0.49 to 1.00 mm, 0.21 to 0.51 mm respectively. The shortest distance between the ICPIOL haptics and the angle of anterior chamber ranged from 1.25 to 1.65 mm. The indentation of iris tissue by the ICPIOL haptics without pigmentary dispersion and distortion of posterior curvature of iris was observed. Conclusion : Adequate space is maintained between the Verisyse myopic ICPIOL and the corneal endothelium, angle, and crystalline lens. Haptic indentation of the iris without pigment erosion and distortion of iris curvature is noted. The ICPIOL implanted in phakic eyes is a safe alternative for treatment of high myopia.
基金Supported by the National Natural Science Foundation of China(20836008,21176132)the Special Research Fund for the Doctoral Program of the Ministry of Education of China(20101012174)
文摘A novel solid support adsorbent for CO2capture was developed by loading pentaethylenehexamine(PEHA)on commercially available mesoporous molecular sieve MCM-41 using wet impregnation method.MCM-41 samples before and after PEHA loading were characterized by X-ray powder diffraction,N2adsorption/desorption,thermal gravimetric analysis and scanning electron microscope to investigate the textural and thermo-physical properties.CO2adsorption performance was evaluated in a fixed bed adsorption system.Results indicated that the structure of MCM-41 was preserved after loading PEHA.Surface area and total pore volume of PEHA loaded MCM-41 decreased with the increase of loading.The working adsorption capacity of CO2could be significantly improved at 60%of PEHA loading and 75°C.The effect of the height of adsorbent bed was investigated and the best working adsorption capacity for MCM-41-PEHA-60 reached 165 mg·(g adsorbent)-1at 75°C.Adsorption/desorption circle showed that the CO2working adsorption capacity of MCM-41-PEHA kept stable.
基金Project(2009ZE56014)supported by the Aeronautical Science Foundation of ChinaProject(gf200901008)supported by the Open Fund of National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology,Nanchang Hangkong University,China
文摘The initiation sites and influencing factors of cavity nucleation were investigated for a Ti-6Al-2Zr-1Mo-1V alloy with lamellar starting structure,using the isothermal hot compression test.All samples were deformed to a true strain of 0.70 in the temperature range of 750-950°C and strain rate range of 0.001-10 s-1.The corresponding microstructures were observed by means of the metallurgical microscopy and scanning electron microscopy(SEM).It was found that all cavities occurred at the bulge regions of the compression specimens.Most of cavities nucleated along prior beta boundaries oriented 45°to the compression axis,while others nucleated at the interfaces of lamellar alpha colonies.Cavity nucleation was inhibited with increasing the volume fraction of beta phase and the volume fraction spheroidized of lamellar alpha phase.
文摘The effect of thixoforming process on morphologies of silicon particles that affect fracture mode of A356 alloy was investigated.Microstructure and fracture surfaces of thixoformed samples were investigated by image analyzing technique and scanning electron microscopy.A new combination parameter, called silicon density ratio (SDR) index, was introduced.SDR index approximates the collective effects of morphological characteristics of silicon particles on microstructure transparency of alloy in crossing the dislocation.It is suggested that samples with lower SDR index have superior mechanical properties, especially elongation, and consequently intergranular fracture mode.On the contrary, samples with higher SDR index have inferior mechanical properties and fracture path tends to propagate along the cell boundaries leading to transgranular fracture.
文摘The presence of sperm was observed in different organs of the reproductive tract of M. schmitti. These were the club, baffle and terminal zone of the oviducal gland, posterior portion of the uterus and in the cervix. This fact allowed for consideration not only its storage but its interaction with the female reproductive tract epithelia as well. SEM (microscopic observation studies) detected loose and sole spermatozoa in the club and baffle zones in a pregnant female. On the other hand, histochemical techniques showed sperm storage tubules of the terminal zone, which contain bundles of sperm, do not stain AB (alcian blue) or PAS (periodic acid schiff). Disintegration of some of the male gametes was observed in the posterior part of the uterus with TEM (transmission electron microscopy) studies which would indicate a first uterine sperm selection. The uterine epithelial cells involved in this process showed an important level of secretion vacuoles suggesting an interaction with sperm cells. Sperm in the cervix was found without the matrix that constitutes the spermatozeugmata formed in the male tract. Some heads of the sperm were uncurled while they were interacting with the cervical cells.
基金Project(2007CB613702) supported by the National Basic Research Program of ChinaProject(CSTD2006AA4012) supported by the Key Technologies R&D Program of the Chongqing Science and Technology Commission
文摘Mg-1.5Zn-0.2Zr-xCe (x=0, 0.1, 0.3, 0.5, mass fraction, %) alloys were prepared by conventional semi-continuous casting. The effect of rare earth Ce on the microstructure of Mg-1.5Zn-0.2Zr-xCe alloys was studied and the distribution of Ce was analyzed by optical microscopy (OM), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results indicate that Ce element exists in the form of Mg12Ce phase and has an obvious refining effect on the microstructure of test alloys. As the Ce content increases, the grain size reduces, the grain boundaries turn thinner, and the distribution of Mg12Ce precipitates becomes more and more dispersed. The Mg-1.5Zn-0.2Zr alloy with 0.3%Ce has the best refinement effect. From center to periphery of the ingot, the amount of granular precipitates in the grain reduces. In longitudinal section of the ingot, some relative long columnar grains appear.
文摘Anatomical structure of differently originated seed envelopes in one-seeded indehiscent fruits of Urticaceae and Asteraceae members is studied using light and scanning electron microscopes. It was found that in anthocarps and involucrate fruits of both families the relations between the primary (pericarp) and secondary fruit envelopes (perianth and/or involucre) were composed under complexification (union) type, and not as substitution. Numerous examples of non-homologous resemblance in fruit envelope structure indicate a high degree of adaptability of certain histological types, recurring on a different morphological basis in different phyletic lines within a family. These tissue complexes represent widely occurring types of the pericarp (Utricaceae) or pericarp and seed coat tissue union (Asteraceae). This evolutionary repetition or pseudocyclic resemblance is apparently another common regularity of one-seeded indehiscent fruits evolution in addition to those enumerated in general by Zohary (1950).