1,284 research outputs found
Effects of annealing time on structural and magnetic properties of L10-FePt nanoparticles synthesized by the SiO2-nanoreactor method
We investigated effects of annealing time on structural and magnetic
properties of the L10-FePt nanoparticles synthesized by the SiO2-nanoreacter
method. The magnetization and powder X-ray diffraction studies revealed that
the annealing at 900 oC for 9 hr could convert all of the fcc-nanoparticles to
the well-crystallized L10 structure with a large coercivity while keeping their
particle size. Such monodisperse and highly crystalline L10-FePt nanoparticles
are a promising material for the realization of ultra-high density recording.Comment: 9 pages, 2 figure
Pembentukan Monolayer Azobenzen Disulfida dan Karakterisasinya
Dalam penelitian ini dilakukan studi kinetik adsorpsi pembentukan monolayer azobenzen disulfida pada substrat Au. Ada tiga jenis molekul azobenzen disulfida yang digunakan yaitu HAzC12SSC12, C6AzC12SSC18, dan CNAzC12SSC12. Pengkajian tersebut dilakukan dengan pengukuran kinetik adsorpsi monolayer azobenzen disulfida dan spektrum SPR dengan menggunakan spektroskopi surface plasmon resonance (SPR). Hasil yang didapat menunjukkan molekul C6AzC12SSC18 memiliki potensi yang lebih baik untuk membentuk self-assembled monolayer (SAMs), karena memiliki tahapan adsorpsi yang cepat dengan ketebalan yang optimal dan penyusunan molekul yang teratur
Possible role of Krüppel-like factor 5 in the remodeling of small airways and pulmonary vessels in chronic obstructive pulmonary disease
BACKGROUND: Small airway remodeling is an important cause of the airflow limitation in chronic obstructive pulmonary disease (COPD). A large population of patients with COPD also have pulmonary hypertension. Krüppel-like factor 5 (KLF5) is a zinc-finger transcription factor that contributes to tissue remodeling in cardiovascular diseases. Here, we evaluate the possible involvement of KLF5 in the remodeling of small airways and pulmonary vessels in COPD. METHODS: Lung tissues were obtained from 23 control never-smokers, 17 control ex-smokers and 24 ex-smokers with COPD. The expression of KLF5 in the lung tissues was investigated by immunohistochemistry. We investigated whether oxidative/nitrosative stress, which is a major cause of the pathogenesis in COPD, could augment the production of KLF5. We examined the role of KLF5 in the stress-mediated tissue remodeling responses. We also investigated the susceptibility of KLF5 expression to nitrosative stress using bronchial fibroblasts isolated from the lung tissues. RESULTS: The expression of KLF5 was up-regulated in the small airways and pulmonary vessels of the COPD patients and it was mainly expressed in bronchial fibroblasts and cells of the pulmonary vessels. The extent of the KLF5 expression in the small airway of the COPD group had a significant correlation with the severity of the airflow limitation. Oxidative/nitrosative stress augmented the production of KLF5 in lung fibroblasts as well as the translocation of KLF5 into the nuclei. Silencing of KLF5 suppressed the stress-augmented differentiation into myofibroblasts, the release of collagens and metalloproteinases. Bronchial fibroblasts from the patients with COPD highly expressed KLF5 compared to those from the control subjects under basal condition and were more susceptible to the induction of KLF5 expression by nitrosative stress compared to those from the control subjects. CONCLUSION: We provide the first evidence that the expression of KLF5 is up-regulated in small airways and pulmonary vessels of patients with COPD and may be involved in the tissue remodeling of COPD
Forces between clustered stereocilia minimize friction in the ear on a subnanometre scale
The detection of sound begins when energy derived from acoustic stimuli
deflects the hair bundles atop hair cells. As hair bundles move, the viscous
friction between stereocilia and the surrounding liquid poses a fundamental
challenge to the ear's high sensitivity and sharp frequency selectivity. Part
of the solution to this problem lies in the active process that uses energy for
frequency-selective sound amplification. Here we demonstrate that a
complementary part involves the fluid-structure interaction between the liquid
within the hair bundle and the stereocilia. Using force measurement on a
dynamically scaled model, finite-element analysis, analytical estimation of
hydrodynamic forces, stochastic simulation and high-resolution interferometric
measurement of hair bundles, we characterize the origin and magnitude of the
forces between individual stereocilia during small hair-bundle deflections. We
find that the close apposition of stereocilia effectively immobilizes the
liquid between them, which reduces the drag and suppresses the relative
squeezing but not the sliding mode of stereociliary motion. The obliquely
oriented tip links couple the mechanotransduction channels to this least
dissipative coherent mode, whereas the elastic horizontal top connectors
stabilize the structure, further reducing the drag. As measured from the
distortion products associated with channel gating at physiological stimulation
amplitudes of tens of nanometres, the balance of forces in a hair bundle
permits a relative mode of motion between adjacent stereocilia that encompasses
only a fraction of a nanometre. A combination of high-resolution experiments
and detailed numerical modelling of fluid-structure interactions reveals the
physical principles behind the basic structural features of hair bundles and
shows quantitatively how these organelles are adapted to the needs of sensitive
mechanotransduction.Comment: 21 pages, including 3 figures. For supplementary information, please
see the online version of the article at http://www.nature.com/natur
PEMBENTUKAN MONOLAYER AZOBENZEN DISULFIDA DAN KARAKTERISASINYA
Dalam penelitian ini dilakukan studi kinetik adsorpsi pembentukan monolayer azobenzen disulfida pada substrat Au. Ada tiga jenis molekul azobenzen disulfida yang digunakan yaitu HAzC12SSC12, C6AzC12SSC18, dan CNAzC12SSC12. Pengkajian tersebut dilakukan dengan pengukuran kinetik adsorpsi monolayer azobenzen disulfida dan spektrum SPR dengan menggunakan spektroskopi surface plasmon resonance (SPR). Hasil yang didapat menunjukkan molekul C6AzC12SSC18 memiliki potensi yang lebih baik untuk membentuk self-assembled monolayer (SAMs), karena memiliki tahapan adsorpsi yang cepat dengan ketebalan yang optimal dan penyusunan molekul yang teratur.Kata Kunci : Self-assembled monolayer, azobenzen disulfida, surface plasmon resonanc
Production of scFv-Conjugated Affinity Silk Powder by Transgenic Silkworm Technology
Bombyx mori (silkworm) silk proteins are being utilized as unique biomaterials for medical applications. Chemical modification or post-conjugation of bioactive ligands expand the applicability of silk proteins; however, the processes are elaborate and costly. In this study, we used transgenic silkworm technology to develop single-chain variable fragment (scFv)-conjugated silk fibroin. The cocoons of the transgenic silkworm contain fibroin L-chain linked with scFv as a fusion protein. After dissolving the cocoons in lithium bromide, the silk solution was dialyzed, concentrated, freeze-dried, and crushed into powder. Immunoprecipitation analyses demonstrate that the scFv domain retains its specific binding activity to the target molecule after multiple processing steps. These results strongly suggest the promise of scFv-conjugated silk fibroin as an alternative affinity reagent, which can be manufactured using transgenic silkworm technology at lower cost than traditional affinity carriers
53BP1 is required for class switch recombination
53BP1 participates early in the DNA damage response and is involved in cell cycle checkpoint control. Moreover, the phenotype of mice and cells deficient in 53BP1 suggests a defect in DNA repair (Ward et al., 2003b). Therefore, we asked whether or not 53BP1 would be required for the efficient repair of DNA double strand breaks. Our data indicate that homologous recombination by gene conversion does not depend on 53BP1. Moreover, 53BP1-deficient mice support normal V(D)J recombination, indicating that 53BP1 is not required for “classic” nonhomologous end joining. However, class switch recombination is severely impaired in the absence of 53BP1, suggesting that 53BP1 facilitates DNA end joining in a way that is not required or redundant for the efficient closing of RAG-induced strand breaks. These findings are similar to those observed in mice or cells deficient in the tumor suppressors ATM and H2AX, further suggesting that the functions of ATM, H2AX, and 53BP1 are closely linked
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