The carbon-containing molecule can be used as an NMR probe to explore the acidic and structural features of various catalytic materials. Thereinto, although mesityl oxide (MO) has been extensively employed to determine the acidity of solution and ionic liquid systems, could it be utilized to characterize the acidic properties of solid acid catalysts? In this work, on the basis of a series of isolated Brønsted and Lewis acid models with varied acid strengths, the adsorption configurations and corresponding 13C chemical shifts of adsorbed MO molecules have been comprehensively studied by means of a theoretical investigation approach. Among them, both the 13C chemical shift difference between β and α carbon atoms (Δδ), and the 13C chemical shift of β carbon atoms (δ13Cβ) in adsorbed MO molecules were explicitly demonstrated to be closely related to the intrinsic acid strength of Brønsted acid sites. These correlations could be utilized to quantitatively scale the Brønsted acid strength of solid acid catalysts. Besides, a moderate relationship was theoretically derived for the relevant 13C NMR parameters and intrinsic Lewis acid strength.
A novel, unique, and effective method for carbon nanotube (CNT) dispersion by the free arc stimulation is proposed. CNTs are introduced as an aerogel into the air space via the dispersion method and can be utilized as a solution by adding it to solvents. The volume of the original generated CNT aerogel with a high-volume expansion ratio displays a performance two orders of magnitudes better than that of raw CNTs, which is considered a powerful characterization of the dispersion effect. The CNT aerogel, which was observed by scanning electron microscopy also showed a satisfactory dispersion morphology. Its structure and properties were tested before and after dispersion by Raman spectroscopy and great consistency was observed, which proved that the CNTs were undamaged. This approach may greatly promote the large-scale application of CNTs.
This study investigates the relationship between B&B customers’ perceived service quality, satisfaction and repurchase intention. Based on literature review, the customers and managers of selected B&Bs in some Chinese provinces were interviewed for additional sub-dimension possibility for the SERVPERF model and a service recovery sub-dimension was thus added. A questionnaire consisting of 40 questions were designed, using a fivepoint Likert-type scale ranging from “1” reflecting "strongly disagree" to “5” "strongly agree". This study collected data via an online survey platform “WJX” from experienced Chinese B&B customers’ who had staying in a B&B at least once in a B&B in China one year prior to data collection. A pilot test was conducted and some of the question items were slightly amended for easier understanding. In March 2017, the main survey was conducted and 356 questionnaires were received. This study contributes to the body of knowledge in two folds. It not only unveils customers’ perceived service quality in a rapidly developing B&B industry in China but also offers B&B owners/managers insights on how to better engage their customers in enhancing their satisfaction and ultimately repurchase intention. Some conclusions can be drawn from this study. First, the B&Bs in China should pay attention to improving customers’ perceived service quality by optimizing their marketing network and channels to facilitate better internal exchange among B&B owners/managers. Second, it is advisable to strengthen the training of service providers in instilling the importance of service recovery and to actively communicate with the in-house guests to enhance customer satisfaction. Third, the B&Bs should offer quality service to not only improve customer satisfaction as a whole but also enhance customers’ willingness to return. Lastly, the B&Bs should bring local characteristics of "people" into play, relying on local products and service resources, deepening the cultural connotation of the B&B.
Taguchi’s experimental design was employed in the melt spinning of molten mesophase pitch to produce carbon fibers. The textures of the obtained carbon fibers were radial with varied crack angles, as observed by scanning electron microscopy and polarized optical imaging. The diameter, crack angle, preferred orientation, and tensile modulus of the produced samples were examined to investigate the influence of four spinning variables. The relative importance of the variables has been emphasized for each characteristic. The results show that thicker carbon fiber can be obtained with a smaller entry angle, a higher spinning temperature, a reduced winding speed, and an increased extrusion pressure. The winding speed was found to be the most significant factor in relation to the fiber diameter. While it was observed that thicker carbon fiber generally shows improved preferred orientation, the most important variable affecting the preferred orientation was found to be the entry angle. As the entry angle decreased from 120° to 60°, the shear flow was enhanced to induce more ordered radial alignment of crystallite planes so as to obtain carbon fibers with a higher degree of preferred orientation. As a consequence, the crack angle was increased, and the tensile modulus was improved.
With the rapid development of science and technology, big data has been applied in many fields and has brought commercial revolution[1]. The scientific community generally regards big data as "massive data + complex types of data". Commercial applications are more concerned about big data as an analytical (prediction) method and focus on the potential commercialization of analysis results. All walks of life will produce large amounts of data every day. The transition of data-scale brings huge commercial value, which will certainly bring the innovation of business model[2]. Particularly in the internet and other emerging industries, because they get data more convenient and fast. Like Amason, Facebook, Google etc, they use analysis of big data to innovate their business model for maximizing their profits[3], actually business model refers to "an enterprise’s profitable operation mode plus ways to make money"[4]. So the effectiveness of business model innovation of big data on emerging industries has been remarkable. But the impact of big data on traditional industries is still in the exploratory stage. Traditional industry mainly refers to the labor intensive, manufacturing oriented industries, including the traditional commerce and service industry[5]. Learning from the experience of big data on business model innovation of emerging industries, traditional industries can use big data to subvert the business model and accelerate the transformation and upgrading.
To increase the capacitance of an Al electrolytic capacitor, the anodic oxide film, Al2O3, was partly replaced by an Al2O3-ZrO2 (Al-Zr) composite film prepared by the vacuum infiltration method and anodization. The microstructure and composition of the prepared samples were investigated by scanning electron microscopy and transmission electron microscopy. The coated and anodized samples showed multi-layer structures, which consisted of an inner Al hydrate layer, a middle Al- Zr composite layer, and an outer Al2O3 layer. The thickness of the coating layer could go up to 220 nm when the etched Al foil was coated 8 times. The electrical properties of the samples, such as specific capacitance, leakage current, and withstanding voltages, were also characterized after anodization at 100 V and 600 V. The capacitances of samples with ZrO2 coating were 36.3% and 27.5% higher than those of samples without ZrO2 coating when anodized at 100 V and 600 V, respectively.
The oxide films formed on etched aluminum foils play an important role as dielectric layers in aluminum electrolytic capacitors. Y2O3-doped ZrO2 (YZ) films were coated on the etched aluminum foils by sol-gel dip coating, and the electrical properties of YZ-coated Al foils were characterized. YZ films annealed at 450 oC were crystallized into a cubic phase, and as the Y2O3 doping content increased, the unit cell of ZrO2 expanded and the grain size decreased. The etch pits of Al foils were filled by YZ sol when it dried at atmospheric pressure after repeating for several times, but this step could essentially be avoided when being dried in a vacuum. YZ-coated foils indicated that the specific capacitance and dissipation factor were 2-2.5 μF/cm2 and 2-4 at 1 kHz, respectively, and the leakage current and withstanding voltage of films approximately 200 nm thick were 5 × 10−4A at 21 V and 22 V, respectively. After being anodized at 500 V, the foils exhibited a specific capacitance and dissipation factor of 0.6-0.7 μF/cm2 and 0.1-0.2, respectively, at 1 kHz, while the leakage current and withstanding voltage were 2 × 10−4 - 3 × 10−5 A at 400 V and 420-450 V, respectively. This suggests that YZ film is a promising dielectric that can be used in high voltage Al electrolytic capacitors.
ZrO2 films were coated on aluminum etching foil by the sol-gel method to apply ZrO2 as a dielectric material in an aluminum(Al) electrolytic capacitor. ZrO2 films annealed above 450˚C appeared to have a tetragonal structure. The withdrawal speed during dip-coating, and the annealing temperature, influenced crack-growth in the films. The ZrO2 films annealed at 500˚C exhibited a dielectric constant of 33 at 1 kHz. Also, uniform ZrO2 tunnels formed in Al etch-pits 1μm in diameter. However, ZrO2 film of 100-200 nm thickness showed the withstanding voltage of 15 V, which was unsuitable for a high-voltage capacitor. In order to improve the withstanding voltage, ZrO2-coated Al etching foils were anodized at 300 V. After being anodized, the Al2O3 film grew in the directions of both the Al-metal matrix and the ZrO2 film, and the ZrO2-coated Al foil showed a withstanding voltage of 300 V. However, the capacitance of the ZrO2-coated Al foil exhibited only a small increase because the thickness of the Al2O3 film was 4-5 times thicker than that of ZrO2 film.
Epigenetic status of the genome of a donor nucleus has an important effect on the developmental potential of cloned embryos produced by somatic cell nuclear transfer (SCNT). In our previous study has results showed that the donor cells treated with 5-aza-2’- deoxyctidine (5-aza-dC, DNA methylation inhibitors) and Trichostatin A (TSA, histone deacetylase inhibitors) could improve the development of porcine nuclear transfer embryos in vitro. In this study we want to investigate why these two drugs treatment with the donor cell can improve the cloning efficiency, whether they can alter the epigenetic status of the genome of the donor nucleus. This study included 6 groups: control group, the donor cell (porcine fetal fibroblast cell) with no treatment; 2.5 nM 5-aza-dC group, the donor cells treated with 2.5 nM 5-aza-dC for 1h; 5-aza-dC group, the donor cells treated with 5 nM 5-aza-dC for 1h; TSA group, the donor cells treated with 50 nM TSA for 1h; 2.5 nM 5-aza-dC+TSA group, the donor cells treated with 2.5 nM 5-aza-dC for 1h and subsequently treated with 50 nM TSA for another 1h; 5-aza-dC+TSA group, the donor cells treated with 5 nM 5-aza-dC and 50 nM TSA together for 1h. The first experiment detected the DNA methylation status in the different groups. After treatment with these two drugs, the DNA methylation level of the donor cells decreased, however there is no significant difference among the groups. This result indicated that the donor cell treatment with 5-aza-dC and TSA can partially alter the DNA methylation status of the donor cells. The second experiment checked the histone acetylation level of the donor cells treated with these two drugs by western blot. TSA, 2.5 nM 5-aza-dC+TSA, 5 nM 5-aza-aC+TSA, these three groups can significantly improve the hisone acetylation level compared with control and 5-aza-dC groups, there is no significant difference among these three groups. The results of this study suggest that the donor cells treated with 5-aza-dC and TSA can partially decrease DNA methylation and can significantly improve the histone acetylation level of the donor cells, these alterations of the epigenetic modification maybe can improve the clonging efficiency.
An understanding of oocyte gene expression is a necessary for the study of early female gamete development. Recently, oocyte has been used in many techniques such as somatic cell nuclear transfer, intracytoplasmic sperm injection and embryonic stem cell derivation. The purpose of this study was to investigate in the proteomes of pig oocytes and identification of differential proteins between using DIGE technique. In this experiment to overcome of limitation of 2D gel method like a low reproducibility and low sensitivity for proteome analysis of very small quantities, 2D fluorescence difference gel electrophoresis (DIGE), which enables co-detection of up to three samples on the same 2DE gels with CyDyes was used for analysis of oocyte proteins. Proteins within an isoelectric point (pI) range of 3 to 10 and a molecular weight (Mw) range of 20~100 kDa were primarily analyzed in DIGE with 2 replications of each sample. Approximately 1000 spots were detected in 2-D gel. Then, image analysis of DeCyder was performed to detect variations in protein spots between mature oocyte and parthenogenesis embryo. In the comparison of mature oocyte and parthenogenesis embryo, 11 spots were identified to be up-regulated proteins and 2 spots to be down-regulated proteins in parthenogenesis embryo, among which proteins were zona pellucida glycoprotein 4, transferrin receptor, apolipoprotein B, L-3-Hydroxyacyl Coa Dehydrogenase Revisited, cytochrome P450 2C33, similar to Monocarboxylate transporter 2, 2'-5' oligoadenylate synthetase 3, interferon alpha/ beta receptor-1, Chloride channel protein 6, pyruvate carboxylase as well as2'-5' oligoadenylate synthetase 3 using MALDI-TOF-MS. These results suggested that differential proteins were present between mature oocyte and parthenogenesis embryo.
An understanding of oocyte gene expression is a necessary for the study of biological development. Recently, Oocyte has been used in many techniques such as somatic cell nuclear transfer (SCNT), intracytoplasmic sperm injection (ICSI) and embryonic stem cell derivation. However, the molecular mechanism underlying porcine oocyte is still unclear. In this study, we present the description of the porcine oocyte proteome. Proteins within the isoelectric point ranges of 3.0 to 10.0 were analyzed separately using 2‐dimensional electrophoresis (2‐DE). About 450 spots were detected in 2‐ D gel of oocytes, stained with Coomassie blue. Subsequent excision of 227 spots from gels and MALDI‐TOF MS analysis allowed the identification of 85 proteins. Our results indicated the composite profiles of proteins in the porcine oocyte. Tubulin beta chain and meiosis‐specific nuclear structural protein 1 antibody was used to confirm those antibody expression levels in immature, mature and parthenogenetic embryo. Western blot analysis showed that expressions of those proteins increased during mature and parthenogenetic embryo. These protein profiles will make available important guides for the study of oocyte function and assist in functional analysis of the proteins.
5‐aza‐2’‐deoxyctidine (5‐aza‐dC) is DNA methylation inhibitor and Trichostatin A (TSA) is histone deacytlase inhibitor, both of them can alter the level of the epigenetic modification of cells. The objective of this study was to investigate the effects of treatment with 5‐aza‐dC and TSA into fetal fibroblasts on the development of porcine nuclear transfer (NT) embryos. In this study, experiments were performed in order to modify epigenetic status in donor cells and evaluate developmental potential of NT embryos. 5‐ aza‐dC or TSA or combining treatment of TSA and 5‐aza‐dC was treated into growing donor cells for 1 h exposure and development of NT embryos was evaluated. Experiment was performed with 3 groups: control group (donor cells without treatment); TSA group (donor cell treated with 50 nM TSA for 1 h); TSA + 5‐aza‐dC group (donor cells were treated with 50 nM TSA and 5 nM 5‐aza‐dC for 1 h); TSA+1/2(5‐aza‐dC) group (donor cells were treated with 50 nM TSA for 1h and subsequently treated with 2.5 nM 5‐aza‐dC for another 1h). When donor cells were individually treated with 5 nM 5‐aza‐dC or 50 nM TSA for 1h, the blastocyst rate of NT embryos increased significantly compared with control group [18.8% vs 13.4% (5 nM 5‐aza‐dC group vs control group), and 26.2% vs 11.8% (50 nM TSA group vs control group), p<0.05]. However, the blastocyst rate in combining treatment group (50 nM TSA + 5 nM 5‐aza‐dC) did not increase compare with control group (12.3% vs 11.8%, p>0.05). When the donor cell were individually treated with 50nM TSA for 1 h firstly and then treated with 2.5 nM 5‐aza‐dC for another 1h, the blastocyst rate was significantly improved compared with control and TSA group (28% vs 10.2% and 23.7%, p<0.05). The present study suggested that donor cells treated with TSA or low concentration of TSA+5‐azadC in short time exposure may enhance the development of porcine NT embryo.
X‐box binding protein‐1 (XBP‐1) is an important regulator of a subset of genes active during endoplasmic reticulum (ER) stress. In the present study, we analyzed XBP‐1 level and location to explore the effect of ER stress on oocyte maturation and developmental competency of porcine embryos in an in vitro culture system. First, we examined the localization of XBP‐1 at different meiotic stages of porcine oocytes and at early stages of parthenogenetic embryo development. Fluorescence staining showed that expression of functional XBP‐1 was weak in mature oocytes and at the one‐cell, two‐cell, and eight‐cell stages of embryos, but abundant at the GV oocyte, four‐cell, morula, and blastocyst stages. In addition, RT‐PCR revealed that both spliced XBP‐1 (XBP‐1s ) and unspliced XBP‐1 (XBP‐1u) were expressed at the GV oocyte, four‐cell, morula, and blastocyst stages. Tunicamycin (TM), an ER stress inducer, blocked porcine embryonic development at the four‐cell stage, exhibiting the effect on embryonic genome activation. Next, porcine embryos cultured in the presence of tauroursodeoxycholate (TUDCA), an ER stress inhibitor, were studied. Total cell numbers and the extent of the ICM increased (p<0.05), whereas the rate of nuclear apoptosis decreased (p<0.05). Moreover, expression of the anti‐apoptotic gene Bcl‐2 increased whereas expression of the pro‐apoptotic genes Bcl‐xl and p53 decreased. The results indicated that inhibition of ER stress enhanced porcine oocyte maturation and embryonic development by preventing ER stress‐mediated apoptosis in vitro.
The pig has been considered to serve as an appropriate model of human disease. Therefore, establishment of porcine embryonic stem cell lines is important. The purpose of the present study was to further work in this direction. We produced porcine parthenogenetic embryos, and separately aggregated two of each of two-cell (2×2), four-cell (2×4), and eight-cell (2×8) embryos derived by parthenogenesis. After culture for 4 days, the developmental ability of the aggregates and total blastocyst cell numbers were evaluated. The percentage of blastocysts was significantly higher in both 2×4- and 2×8-aggregated embryos (58.3±1.9% and 37.2±2.8%, respectively) than in the control or 2×2-aggregated embryos (23.6±1.1% and 12.5±2.4%, respectively). Total blastocyst cell numbers were increased in the 2×4- and 2×8-aggregated embryos (by 44±3.0% and 45±3.3%, respectively) compared with those of control or 2×2-aggregated embryos (30.5±2.1% and 30.7±2.6%, respectively; p<0.05). The levels of mRNA encoding Oct-4 were higher in both the 2×4- and 2×8-aggregated embryos than in the control. When blastocysts derived from 2×4- aggregated embryos or intact normal embryos were cultured on mouse embryonic fibroblast feeder cells to obtain porcine stem cells, blastocysts from aggregated embryos formed colonies that were better in shape compared with those derived from intact blastocysts. Together, the data show that aggregation of porcine embryos not only improves blastocyst quality but also serves as an efficient procedure by which porcine embryonic stem cells can become established.