Ordering of ruthenium cluster carbonyls in mesoporous silica     

W Zhou  JM Thomas  DS Shephard  BFG Johnson  D Ozkaya  T Maschmeyer  RG Bell  Q Ge 《Science (New York, N.Y.)》1998,280(5364):705-708

The anionic ruthenium cluster carbonylates [Ru6C(CO)16]2- or [H2Ru10(CO)25]2- interspersed with bis(triphenylphosphino)iminium counterions (PPN+) are incorporated from solution into the pores of MCM-41 mesoporous silica (3 nanometers in diameter), where they form tightly packed arrays. These arrays were shown by high-resolution transmission electron microscopy, Fourier transform optical diffraction, and computer simulations to be well ordered both along and perpendicular to the axis of the cylindrical pores. In their denuded state produced by gentle thermolysis, the cluster carbonylates yield nanoparticles of ruthenium that are less well ordered than their assimilated precursors but show good activity as hydrogenation catalysts for hexene and cyclooctene. In both their as-prepared and denuded states, these encapsulated clusters are likely to exhibit interesting electronic and other properties.  相似文献   

Photoemission evidence for a remnant fermi surface and a d-wave-like dispersion in insulating Ca2CuO2Cl2     

F Ronning  C Kim  DL Feng  DS Marshall  AG Loeser  LL Miller  JN Eckstein  I Bozovic  Z Shen 《Science (New York, N.Y.)》1998,282(5396):2067-2072

An angle-resolved photoemission study is reported on Ca2CuO2Cl2, a parent compound of high-Tc superconductors. Analysis of the electron occupation probability, n(k), from the spectra shows a steep drop in spectral intensity across a contour that is close to the Fermi surface predicted by the band calculation. This analysis reveals a Fermi surface remnant, even though Ca2CuO2Cl2 is a Mott insulator. The lowest energy peak exhibits a dispersion with approximately the &cjs3539;coskxa - coskya&cjs3539; form along this remnant Fermi surface. Together with the data from Dy-doped Bi2Sr2CaCu2O8+delta, these results suggest that this d-wave-like dispersion of the insulator is the underlying reason for the pseudo gap in the underdoped regime.  相似文献   

Coherent optical control of the quantum state of a single quantum Dot     

NH Bonadeo  J Erland  D Gammon  D Park  DS Katzer  DG Steel 《Science (New York, N.Y.)》1998,282(5393):1473-1476

Picosecond optical excitation was used to coherently control the excitation in a single quantum dot on a time scale that is short compared with the time scale for loss of quantum coherence. The excitonic wave function was manipulated by controlling the optical phase of the two-pulse sequence through timing and polarization. Wave function engineering techniques, developed in atomic and molecular systems, were used to monitor and control a nonstationary quantum mechanical state composed of a superposition of eigenstates. The results extend the concept of coherent control in semiconductors to the limit of a single quantum system in a zero-dimensional quantum dot.  相似文献   

Two‐Dimensional Vibration Spectroscopy of Rice Quality and Cooking     

F. E. Barton  D. S. Himmelsbach  A. M. McClung  E. L. Champagne 《Cereal Chemistry》2002,79(1):143-147

Rice samples were taken from a study of rice milling properties that affect quality. The spectra of milled and cooked samples were taken in the near‐infrared, mid‐infrared, and Raman region. These spectra, two regions at a time, were regressed by a two‐dimensional technique to develop contour maps that indicated the correlation of two spectral regions. These relationships demonstrate that it is possible to recognize the hydration effects caused by gelatinization (cooked samples vs. milled rice). Three water (O‐H stretch) spectral bands (960, 1445, 1,930 nm) in the near‐infrared (NIR) show marked differences between milled and cooked rice. The difference spectra indicated that there were additional phenomena occurring besides the addition of water. These differences are apparent in both C‐O‐H and N‐H bands, which indicate that water is interacting with both starch and protein. The two‐dimensional technique developed in this laboratory was used to get a better interpretation of what occurs during cooking. The Raman spectrum, which is relatively insensitive to water (O‐H stretch), revealed only changes in protein that could be associated with denaturization.  相似文献   

Protein and Apparent Amylose Contents of Milled Rice by NIR‐FT/Raman Spectroscopy     

D. S. Himmelsbach  F. E. Barton  A. M. McClung  E. T. Champagne 《Cereal Chemistry》2001,78(4):488-492

The chemometric calibration of near‐infrared Fourier‐transform Raman (NIR‐FT/Raman) spectroscopy was investigated for the purpose of providing a rigorous spectroscopic technique to analyze rice flour for protein and apparent amylose content. Ninety rice samples from a 1996 collection of short, medium, and long grain rice grown in four states of the United States, as well as Taiwan, Korea, and Australia were investigated. Milled rice flour samples were scanned in rotating cups with a 1,064 nm (NIR) excitation laser using 500 mW of power. Raman scatter was collected using a liquid N₂ cooled Ge detector over the Raman shift range of 175–3,600 cm^‐1. The spectral data was preprocessed using baseline correction with and without derivatives or with derivatives alone and normalization. Nearly equivalent results were obtained using all of the preprocessing methods with partial least squares (PLS) models. However, models using baseline correction and normalization of the entire spectrum, without derivatives, showed slightly better performance based on the criteria of highest r² and the lowest SEP with low bias. Calibration samples (n = 57) and validation samples (n = 33) were chosen to have similar respective distributions for protein and apparent amylose. The best model for protein was obtained using six factors giving r² = 0.992, SEP = 0.138%, and bias = ‐0.009%. The best model for apparent amylose was obtained using eight factors giving r² = 0.985, SEP = 1.05%, and bias = ‐0.006%.  相似文献   

Cytopathological and histopathological diagnosis of canine splenic disorders     

NI Christensen  PJ Canfield  PA Martin  MB Krockenberger  DS Spielman  KL Bosward 《Australian veterinary journal》2009,87(5):175-181

Objectives To determine (1) the common types of canine splenic disorders, and the breeds affected, that are diagnosed by cytopathological and histopathological examination in Sydney, Australia and (2) the accuracy of cytopathological examination compared with histopathological examination for the diagnosis of canine splenic disorders. Design 69 cytopathological and 51 histopathological diagnoses of canine splenic disorders presented to the Veterinary Pathology Diagnostic Services, The University of Sydney during 2006 and 2007 were tabulated and analysed; 17 cases examined both cytopathologically and histopathologically during 2001–07 were also analysed. Results The most common cytopathological diagnoses were benign disorders of growth, vascular disturbances and necrosis (29%), followed by no abnormalities detectable (28%), malignant neoplasms (20%), equivocal diagnoses (20%) and inflammatory disorders (3%). The most common breeds were Kelpie crosses and mixed breeds. The most common histopathological diagnoses were benign disorders of growth, vascular disturbances and necrosis (49%), followed by malignant neoplasms (43%) and inflammatory disorders (8%). The most common breeds were German Shepherd Dogs, Boxers and Maltese Terriers. Cytopathological and histopathological diagnoses were in complete agreement in 59% of cases, partial agreement in 29% and disagreement in 12%. Conclusion Benign disorders of growth, vascular disturbances and necrosis were the most commonly diagnosed canine splenic disorders, both cytopathologically and histopathologically. Kelpie crosses presented most frequently for cytopathological examination. German Shepherd Dogs were the most common breed diagnosed histopathologically with haemangiosarcoma. Although cytopathological and histopathological splenic examinations are complementary for diagnosis, this study has shown a high correlation for complete and partial agreement between the two.  相似文献   

Suberoylanilide hydroxamic acid,a novel histone deacetylase inhibitor,improves the development and acetylation level of miniature porcine handmade cloning embryos          下载免费PDF全文

ZP Li  XR Lu  ZF Xu  QY Liu  B Huang  DS Shi 《Reproduction in domestic animals》2017,52(5):763-774

Histone deacetylase inhibitors (HDACis) can change the histone acetylation and significantly enhance the developmental competence of the pre‐implantation SCNT embryo. To select a proper histone deacetylase inhibitor to improve the success rate and potentially developmental ability of handmade cloning (HMC) embryos of miniature porcine, we compared the effect of two histone deacetylase inhibitors (SAHA vs. VPA) on HMC embryo development, their histone acetylation level and the expression level of relevant genes. The blastocyst rate and number of blastocyst cells of HMC embryos treated with SAHA (SAHA‐HMC) or VPA (VPA‐HMC) were significantly higher than those of control (Control‐HMC), respectively, but there were no significant difference between SAHA‐HMC and VPA‐HMC groups. In addition, the acetylation level (AcH4K8) of Control‐HMC and VPA‐HMC embryos at the blastocyst stage, respectively, was significantly lower than that of in vitro fertilized (IVF) and SAHA‐HMC embryos. However, the acetylation H4K8 of the blastocysts had no significant difference between SAHA‐HMC and the IVF groups. The SAHA‐HMC blastocysts indicated comparative expression levels of Oct4 and HDAC1 (histone deacetyltransferase gene) with those of IVF blastocysts. In contrast, the expression levels of Oct4 were lower and those of HDAC1 were higher in the VPA‐HMC and Control‐HMC blastocysts, respectively, compared to those of the IVF blastocysts. Our results demonstrated that the HMC embryos treated by SAHA could promote the pre‐implantation development and increase the levels of histone H4K8 acetylation and the expression of the OCT4 gene, yet decrease the expression of the HDAC1 gene to the comparable level of the IVF embryos. Our results proved that SAHA may be a better histone deacetylase inhibitor for porcine HMC compared to VPA, and furthermore, it may indicate that SAHA can effectively correct the abnormal histone acetylation during the HMC embryo development and subsequently improve the full‐term developmental potential of the HMC embryos after embryo transplantation.  相似文献   

European Eel Sperm Diluent for Short‐term Storage     

DS Peñaranda  L Pérez  V Gallego  R Barrera  M Jover  JF Asturiano 《Reproduction in domestic animals》2010,45(3):407-415

The sperm of European eel shows a high density and the time of spermatozoa motility is very short after activation with sea water. These characteristics make difficult the sperm handling and its quality assessment. Several diluents were previously described for the Japanese eel obtaining over 3 weeks’ conservation times under refrigeration, but they rendered bad results in the European species. In the present study, several diluents were developed taking as basis the P1 medium, and using different dilution ratios (1 : 50, 1 : 100) and two pH (6.5, 8.5). The effect of the addition of bovine serum albumin (BSA, 2% w/v) was also evaluated. At 24 h, undiluted samples already showed significant lower motility and viability than sperm samples diluted in the different media. The results for diluents with pH 6.5 and 8.5 were different. Spermatozoa diluted in media at pH 6.5 cannot be activated at 24 h, while samples diluted in the diluents with pH 8.5 and added with BSA did not show significant differences with respect to the fresh sperm motility until 48 h. The viability (percentage of alive cells) did not show differences until 1 week, independent of the dilution ratio. After 1 week, the motility was approximately 30% in the media containing BSA, which presented no differences for head size of the spermatozoa (perimeter and area) until 72 h and 1 week, respectively. In conclusion, the combination of one medium having similar physico‐chemical characteristics to the seminal plasma, including pH 8.5, and supplemented with BSA can be used in different dilution ratios for the sperm’s short‐term storage, preserving its motility capacity.  相似文献   

Exogenous DNA Uptake of Boar Spermatozoa by a Magnetic Nanoparticle Vector System     

TS Kim  SH Lee  GT Gang  YS Lee  SU Kim  DB Koo  MY Shin  CK Park  DS Lee 《Reproduction in domestic animals》2010,45(5):e201-e206

The sperm‐mediated gene transfer method is applicable to transgenesis in many species that use spermatozoa for reproduction recently, which has been shown various results. In the current study, we show that transgenic porcine embryos can be efficiently produced by employing a simple transfection method that uses magnetic nanoparticles (MNPs). The complexes formed between plasmid DNA and MNPs were bounded on ejaculated boar spermatozoa at a higher efficiency compared to methods using DNA alone or lipofection. Using confocal microscopy, rhodamine fluorophore‐labelled MNPs were detected on external surfaces of the spermatozoa membrane, which were bounded on zona pellucida of in vitro maturated oocyte during in vitro fertilization. Electron microscopy revealed that clusters of MNPs were detected in inside of plasma membrane and nucleus of the spermatozoa head. Additionally, we found that magnetofected boar spermatozoa could be fertilized with oocytes in vitro and that the resulting gene of green fluorescent protein was detected in fertilized eggs by genomic PCR analysis. Taken together, these results suggest that MNPs can be used to efficiently introduce a transgene into embryo via spermatozoa.  相似文献   

Vasoformative proliferations in a rufous bettong     

P CANFIELD  T BELLAMY  WJ HARTLEY  DS SPIELMAN 《Australian veterinary journal》1990,67(9):334-335

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