[en] A cylindrical hollow cathode discharge (HCD) in CH₄/Ar gas mixture at pressure of 20-30 Pa was used to deposit diamond-like carbon (DLC) films on the inner surface of a stainless steel tube. The characteristics of the HCD including the voltage-current curves, the plasma images and the optical emission spectrum (OES) were measured in Ar and CH₄/Ar mixtures. The properties of DLC films prepared under different conditions were analyzed by means of Raman spectroscopy and scanning electron microscopy (SEM). The results show that the electron excitation temperature of HCD plasma is about 2400 K. DLC films can be deposited on the inner surface of tubes. The ratio of sp³/sp² bonds decreases with the applied voltage and the deposition time. The optimizing CH₄ content was found to be around CH₄/Ar = 1/5 for good quality of DLC films in the present system. (plasma technology)

[en] We investigate the effects of intrinsic noise on Turing pattern formation near the onset of bifurcation from the homogeneous state to Turing pattern in the reaction-diffusion Brusselator. By performing stochastic simulations of the master equation and using Gillespie's algorithm, we check the spatiotemporal behaviour influenced by internal noises. We demonstrate that the patterns of occurrence frequency for the reaction and diffusion processes are also spatially ordered and temporally stable. Turing patterns are found to be robust against intrinsic fluctuations. Stochastic simulations also reveal that under the influence of intrinsic noises, the onset of Turing instability is advanced in comparison to that predicted deterministically

[en] In order to find a non-radioactive and sensitive method for detecting human interleukin 4(IL-4), a quantitative magnetic affinity immunoassay (MAIA) was established based on employing a pair of monoclonal antibodies against IL-4 with distinct epitopes and amplified system of FITC/anti-FITC mAb. the experimental condition, sensitive, precision, accuracy and the application of this method were evaluated. The linearity range of the MAIA measuring IL-4 was 0-3 ng/mL, and the detectable limitation of IL-4 was 10 pg/mL. the average recovery, intra-assay CV and inter-assay CV were 101.7%, 3.6% and 3.6% respectively. Compared with ELISA, the correlation coefficient was 0.9124. Taken together, the quantitative MAIA was established successfully with multi-advantages, which are stable, sensitive, reliable, less sample needed, without radioactive pollution and easy to perform. This method is worthy of recommendation in clinical and basic research application. (authors)

[en] The association between intrinsic noises and deterministic descriptions/properties of the rate equations for chemical reactions is analyzed using the linear noise approximation of the master equation. We illustrate that the effect of intrinsic noise is determined in combination by three components: the system size, the matrix associated with reaction kinetics, and the eigenvalues associated with the system's dissipation. Generally, a more attractive dynamics tends to attenuate the internal fluctuations more significantly because intrinsic noises are inversely proportional to the absolute value of the real part of the eigenvalues. In addition, a higher reaction rate and larger stoichiometry coefficients will give rise to stronger intrinsic noise. (general)

[en] A typical biological cell lives in a small volume at room temperature; the noise effect on the cell signal transduction pathway may play an important role in its dynamics. Here, using the transforming growth factor-β signal transduction pathway as an example, we report our stochastic simulations of the dynamics of the pathway and introduce a linear noise approximation method to calculate the transient intrinsic noise of pathway components. We compare the numerical solutions of the linear noise approximation with the statistic results of chemical Langevin equations, and find that they are quantitatively in agreement with the other. When transforming growth factor-β dose decreases to a low level, the time evolution of noise fluctuation of nuclear Smad2—Smad4 complex indicates the abnormal enhancement in the transient signal activation process. (cross-disciplinary physics and related areas of science and technology)

[en] A proposition based on the fluctuation theorem in thermodynamics is formulated to quantitatively describe molecular evolution processes in biology. Although we cannot give full proof of its generality, we demonstrate via computer simulation its applicability in an example of DNA in vitro evolution. According to this theorem, the evolution process is a series of exponentially rare fluctuations fixed by the force of natural selection. (general)

[en] We systematically investigate the behaviour of pattern formation in a reaction–diffusion system when the system is located near the Turing–Hopf codimension-2 point in phase space. The chloride–iodide–malonic acid (CIMA) reaction is used in this study. A phase diagram is obtained using the concentration of polyvinyl alcohol (PVA) and malonic acid (MA) as control parameters. It is found that the Turing–Hopf mixed state appears only in a small vicinity near the codimension-2 point, and has the form of hexagonal pattern overlapped with anti-target wave; the boundary line separating the Turing state and the wave state is independent of the concentration of MA, only relies on the concentration of PVA. The corresponding numerical simulation using the Lengyel–Epstein (LE) model gives a similar phase diagram as the experiment; it reproduces most patterns observed in the experiment. However, the mixed state we obtain in simulation only appears in the anti-wave tip area, implying that the 3-D effect in the experiments may change the pattern forming behaviour in the codimension-2 regime

[en] The SOS (save our soul) response induced by DNA damage in bacteria E coli has raised a great interests in biophysics and has been extensively studied. Previously we have developed a stochastic simulation model to explain the oscillatory-like modulation of SOS gene expression observed in experiment. Here we present an improved semi-stochastic model which has higher simulation efficiency taking into account the updated knowledge about SOS response. The improved model suggests that frequency of the modulation is controlled by the negative feedback in the system. DNA polymerase V, the key enzyme for error-prone translesion synthesis during SOS response, plays a major role in closing up the negative feedback. It is also indicated that the correlation between the modulation and cellular growth observed in experiment is due to DNA damage induced slowing down of transcription and translation. (cross-disciplinary physics and related areas of science and technology)

[en] We report stochastic simulations of the yeast mating signal transduction pathway. The effects of intrinsic and external noise, the influence of cell-to-cell difference in the pathway capacity, and noise propagation in the pathway have been examined. The stochastic temporal behaviour of the pathway is found to be robust to the influence of inherent fluctuations, and intrinsic noise propagates in the pathway in a uniform pattern when the yeasts are treated with pheromones of different stimulus strengths and of varied fluctuations. In agreement with recent experimental findings, extrinsic noise is found to play a more prominent role than intrinsic noise in the variability of proteins. The occurrence frequency for the reactions in the pathway are also examined and a more compact network is obtained by dropping most of the reactions of least occurrence

[en] Objectives: To clarify differences between solitary pulmonary inflammatory lesions and peripheral lung cancers with contrast-enhanced computed tomography. Methods: In total, 64 and 132 patients with solitary pulmonary inflammatory masses/nodules and peripheral lung cancers, respectively, were enrolled in this study. Their computed tomographic findings were summarized and compared retrospectively. Results: Compared with the peripheral lung cancers, the inflammatory lesions were located closer to the pleura (p<0.0001). The majority of the inflammatory lesions were patchy and oval-shaped (82.8%), whereas most of the tumors were lobulated (82.6%). Almost all the inflammatory cases were unclear (93.8%), whereas most of the tumors had speculated margins (72.7%). Computed tomography values were significantly higher for the inflammatory lesions than for the cancers (p<0.0001). More than half of the inflammatory lesions had defined necrosis (59.3%). Furthermore, 49.2% of the cancers enhanced inhomogeneously, but only 24.6% had ill-defined necrosis or cavities. The peripheral zones of 98.4% of the inflammatory lesions and 72.7% of the tumors were unclear, with peripheral scattered patches (92.2%) and beam-shaped opacity (66.7%) being the most common findings, respectively. Adjacent pleural thickening was more frequent for the inflammatory lesions than the cancers (95.3% vs. 21.1%, p<0.0001), whereas pleural indentation was found in 67.4% of the subjects with cancer. In addition, hilar (p=0.034) and mediastinal (p=0.003) lymphadenopathy were more commonly detected in the cancers than in the inflammatory cases. Conclusions: Contrast-enhanced computed tomography findings for pulmonary inflammatory lesions and peripheral lung cancers were significantly different in many aspects. Developing a comprehensive understanding of these differences is helpful for directing their management. (author)