Anticancer Activity of 2-O-caffeoyl Alphitolic Acid Extracted from the Lichen,Usnea barbata 2017-KL-10

Colorectal cancer is one of the life-threatening ailments causing high mortality and morbidity worldwide. Despite the innovation in medical genetics, the prognosis for metastatic colorectal cancer in patients remains unsatisfactory. Recently, lichens have attracted the attention of researchers in the search for targets to fight against cancer. Lichens are considered mines of thousands of metabolites. Researchers have reported that lichen-derived metabolites demonstrated biological effects, such as anticancer, antiviral, anti-inflammatory, antibacterial, analgesic, antipyretic, antiproliferative, and cytotoxic, on various cell lines. However, the exploration of the biological activities of lichens’ metabolites is limited. Thus, the main objective of our study was to evaluate the anticancer effect of secondary metabolites isolated from lichen (Usnea barbata 2017-KL-10) on the human colorectal cancer cell line HCT116. In this study, 2OCAA exhibited concentration-dependent anticancer activities by suppressing antiapoptotic genes, such as MCL-1, and inducing apoptotic genes, such as BAX, TP53, and CDKN1A(p21). Moreover, 2OCAA inhibited the migration and invasion of colorectal cancer cells in a concentration-dependent manner. Taken together, these data suggest that 2OCAA is a better therapeutic candidate for colorectal cancer.     

Plasma property effects on spectral line broadening in double-pulse laser-induced breakdown spectroscopy

Double-pulse Laser-Induced Breakdown Spectroscopy (LIBS) in an orthogonal configuration was used to investigate plasma temperature and electron density effects on Mg II emission spectral line broadening. The experiments were carried out with two Nd:YAG lasers, one operating at 355 nm for ablation and the other one at 1064 nm for plasma reheating in air at atmospheric pressure. Temporally resolved plasma temperature and electron density were measured at various delay times. Data in this study show prolonged emission of Mg II (280.27 nm) as well as enhancement of the signal intensity when using double-pulse excitation compared to the single-pulse case. An enhancement of ～8× was attained with a delay between the laser pulses equal to 1 μs. The enhancement was accompanied by higher plasma temperature and increased electron density. The double-pulse LIBS configuration provides energy to sustain the plasma emission at a period in time when the linewidth is minimum, thereby improving the analytical capabilities of low spectral resolution instrumentation typically used in LIBS system.     

Electron-beam deposition of vanadium dioxide thin films

Developing a reliable and efficient fabrication method for phase-transition thin-film technology is critical for electronic and photonic applications. We demonstrate a novel method for fabricating polycrystalline, switchable vanadium dioxide thin films on glass and silicon substrates and show that the optical switching contrast is not strongly affected by post-processing annealing times. The method relies on electron-beam evaporation of a nominally stoichiometric powder, followed by fast annealing. As a result of the short annealing procedure we demonstrate that films deposited on silicon substrates appear to be smoother, in comparison to pulsed laser deposition and sputtering. However, optical performance of e-beam evaporated film on silicon is affected by annealing time, in contrast to glass.     

Modification of microstructures and physical properties of ultra high molecular weight polyethylene by electron beam irradiation

An ultra high molecular weight polyethylene was irradiated with the electron beam at dose levels ranging from 100 kGY to 1 MGy. The microstructures of the irradiated samples were characterized by FTIR, gel fraction measurement, DSC, and small‐ and wide‐angle X‐ray scattering. For the mechanical properties, a static tensile test and creep experiment were also performed. The crosslinking and the crystal morphology changes were the main microstructural changes to influence the mechanical properties. It was found that 250 kGy appeared to be the optimal dose level to induce crosslinks in the amorphous area and recrystalliztion in the crystal lamellae. At doses above 250 kGy, the electron beam penetrates into the crystal domains, resulting in crosslinks in the crystal domains and reduction in the crystal size and crystallinity. The static mechanical properties (modulus, strength) and the creep resistance were enhanced by the electron beam irradiation. The stiffness rather correlated with the degree of crosslinks while the strength with the crystal morphology. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3019–3029, 2005     

The effect of temperature on collision induced intersystem crossing in the reaction of CH2 with H2

Laser flash photolysis of ketene at 308 nm, coupled with H atom vacuum ultraviolet laser induced fluorescence, was used to determine the branching ratio for the CH₃ + H channel (1a) in the reaction of CH₂¹A₁ (¹CH₂) with H₂, over the temperature range 300–500 K. This reaction channel competes with collision induced intersystem crossing (CIISC) to form triplet methylene, CH₂³B₁ (³CH₂) (channel 1b). The branching ratio for H formation, k_1a/k₁, was determined by measuring the relative H atom yield in three time resolved measurements of H: (i) in ketene, H₂ mixtures, where H is exclusively formed by reaction 1a, (ii) in ketene, H₂, NO mixtures ([NO] [H₂]), where H is formed at short times by 1a and at longer times by ³CH₂ + NO, following 1b, and (iii) in ketene, He, NO mixtures ([NO] [He]), where H is exclusively formed from ³CH₂ + NO, following deactivation of singlet to triplet methylene by He. k_1a/k₁ was found to increase from 0.85 at 300 K to unity at 500 K, with the yield of CIISC decreasing from 0.15 to zero. This is the first measurement of the temperature dependence of the rate coefficient for CIISC in a reactive system. The rate coefficient for CIISC with an inert gas increases with T. It has been suggested that the fractional yield of CIISC will increase with temperature in reactive systems, thus reducing the rate coefficient for reaction at high temperature, with significant consequences for combustion systems. The present experiments demonstrate that this is not the case for reaction with H₂ and implies a different CIISC mechanism for reactive vs inert collision partners.     

Subband coding using human visual characteristics for image signals

A subband coder which can be applied to various kinds of images such as HDTV (high-definition television), digital TV, and videophone is proposed using human visual characteristics. Data compression is achieved by the procedure based on human visual characteristics, where motion vectors in lower band are utilized to process components in higher band according to the degree of movement. Since the compression of the signal in higher band is accomplished by motion information, the proposed method shows good performance regardless of the degree of movement. Compared with the existing methods, which uniformly process all subblocks in the same subband, the quality of the image reconstructed by the proposed method is shown to be superior     

1/f noise of GaAs resistors on semi-insulating substrates

A new theory is used to analyze the 1/f noise of GaAs resistors on semi-insulating substrates. It is demonstrated that this model can explain previously published results at moderately high frequencies for, in this example, resistive filaments on semi-insulating GaAs substrates. The model is based on a distributed equivalent circuit representation of the substrate, and shows that 1/f noise is a bulk phenomenon associated with the high resistivity substrates. The 1/f noise is not associated with number or mobility fluctuations in the channel, nor surface effects. One consequence of the theory is that in this particular instance Hooge's parameter is in reality no parameter, but is given by a simple formula which has a simple physical interpretation as the ratio of two charges: the thermal charge developed across the substrate capacitance and the charge associated with ionized donors in the resistor channel     

Observations of vacuum spark dynamics from its X-ray emission

The behavior of a medium energy (~1 kJ) pulse-power-driven vacuum spark is shown to depend on the electrode material and form of the anode in otherwise similar conditions of operation. The dynamical evolution of the discharge is followed from its soft X-ray emission. The electrode materials compared are titanium and aluminum with a form of anode that is tubular or conical. The use of a tubular anode favors a more uniform sheath and a better formation of a dense Z-pinch and the ensuing hot spots are found to be at least twice as bright. The position of the brightest spots differs according to the material and the electrode shape, and is found to coincide with the shape of the sheath. The energy output is measured and the density of the plasma in the hot spots may be calculated     

Interference mitigation using transmitter filters in CDMA systems

We consider the use of transmitter filters as pre-equalizers at the base station to mitigate the interference in code-division multiple-access (CDMA) systems over a multipath fading channel. It is shown that the interference at the receiver of the mobile station can be mitigated by the transmitter filters and, thereby, the capacity of downlink channel can be improved. The minimum variance distortionless response (MVDR) beamforming technique in antenna arrays has been utilized to find the coefficients of the interference mitigation (IM) transmitter filters. To design IM transmitter filters, we assume that the channel information is available. This can be true in the time-division duplexing (TDD) mode because of the channel reciprocity. In the frequency-division duplexing mode, the downlink channel impulse responses (CIRs) shall be be transmitted to the base station. To transmit the CIRs, we consider an encoding method. In addition, to compensate inherent feedback delay, the channel prediction is also utilized     

An empirical real-time approximation of waiting time distributionin MMPP(2)/D/1

We propose a simple, empirical real-time approximation method for calculating the waiting time distribution for the MMPP(2)/D/1 system. Our approach is based on approximation using a two-term exponential function. We match the poles, the residue for the asymptotic constant, and the mean waiting time between the Laplace transforms of the exact distribution and the approximate distribution. Numerical examples show that our method yields quite accurate results over a wide range. The result can be adopted in evaluating asynchronous transfer mode (ATM) multiplexers for real-time ATM traffic control