408 research outputs found
Measure solutions to piston problem for compressible fluid flow of generalized chaplygin gas
We study the piston problem of the compressible fluid flow with the
generalized Chaplygin gas. Depending on the inferential critical value of Mach
number, we prove that, there exists an integral weak solution for the
proceeding piston problem, consisting of a shock separating constant states
ahead of the piston if Mach numbers less than this critical value, while a
singular measure solution, with density containing a Dirac measure supported on
the piston, shall be proposed to solve the proceeding piston problem if Mach
numbers greater than or equal to the critical value. For the receding piston
problem, rarefaction wave solution always exists when the piston recedes from
the gas with any constant speed. Moreover, the occurrence of vacuum state and
the convergence of solutions, as well as degeneration of equations are analyzed
in the receding case as Mach number tends to infinity.Comment: 15 page
Research on the transition dynamics and linear (nonlinear) optical properties of mCherry
In this study, we explore the electron transition mechanism and optical
properties of the popular red fluorescent protein mCherry. By examining the
charge transfer spectrum and combining it with the mCherry hole-electron
distribution, we identify that the charge transfer between the phenolate and
imidazolinone loops significantly contributes to the absorption spectrum.
Quantitative analysis of charge transfer shows that, overall, the electrons are
transferred to the C16 atom in the middle of phenolate and the imidazolinone
loops during absorption. We speculate that C16 may also absorb protons to
enable the photoconversion of mCherry in the excited state, similar to the
blinking mechanism of IrisFP. In addition, we further investigated the optical
properties of mcherry in the external field by polarizability
(hyperpolarizability), showing the anisotropy of the polarization, the first
hyperpolarization and the second hyperpolarization by unit spherical
representation. Our results suggest that significant polarization and second
hyperpolarizability occur when the field direction and electron transfer
direction are aligned. We also analyzed the polarizability and first
hyperpolarizabilities for different external fields. The polarizability mutated
when the external field satisfies the S_0,min-> S_1 transition. Finally, the
study of the first hyperpolarizability shows that adjusting the appropriate
field can lead to a linear photoelectric effect or second harmonic generation
of mCherry. These studies have certain reference values for various red
fluorescent protein correlation simulations and experiments because of the
similarity of the red fluorescent protein
Uncertainty Quantification of Power Spectrum and Spectral Moments Estimates Subject to Missing Data
In this paper, the challenge of quantifying the uncertainty in stochastic process spectral estimates based on realizations with missing data is addressed. Specifically, relying on relatively relaxed assumptions for the missing data and on a kriging modeling scheme, utilizing fundamental concepts from probability theory, and resorting to a Fourier-based representation of stationary stochastic processes, a closed-form expression for the probability density function (PDF) of the power spectrum value corresponding to a specific frequency is derived. Next, the approach is extended for also determining the PDF of spectral moments estimates. Clearly, this is of significant importance to various reliability assessment methodologies that rely on knowledge of the system response spectral moments for evaluating its survival probability. Further, utilizing a Cholesky decomposition for the PDF-related integrals kept the computational cost at a minimal level. Several numerical examples are included and compared against pertinent Monte Carlo simulations for demonstrating the validity of the approach
Adaptive algorithm for increasing image rejection ratio in Low-IF receivers
An adaptive method for compensating mismatch effect on an I/Q demodulation is presented. It is based on the correlation between the desired and image band that appears when there is a mismatch in any branch. The proposed algorithm is specially intended for narrowband low-IF receivers. No calibration source is neccesary. Up to 91 dB of image rejection ratio is achieved with narrow-bandwidth signals (up to 6.25% of the sampling frequency)
Yi-Zhi-Fang-Dai Formula Protects against A β
Yi-Zhi-Fang-Dai formula (YZFDF) is an experiential prescription used to cure dementia cases like Alzheimer’s disease (AD). In this study, the main effective compounds of YZFDF have been identified from this formula, and the neuroprotective effect against Aβ1–42 oligomer of YZFDF has been tested in SH-SY5Y cells. Our results showed that YZFDF could increase cell viability and could attenuate endothelial reticula- (ER-) mediated apoptosis. Evidence indicated that protein folding and endothelial reticula stress (ERS) played an important role in the AD pathological mechanism. We further explored the expression of Hsp70, an important molecular chaperon facilitating the folding of other proteins, and Grp78, the marker protein of ERS in SH-SY5Y cells. Data told us that YZFDF pretreatment could influence the mRNA and protein expression of these two proteins. At last, we also found that YZFDF pretreatment could activate Akt in SH-SY5Y cells. All these above indicate that YZFDF could be a potent therapeutic candidate for AD treatment
Triggerable plasmalogen liposomes: improvement of system efficiency
AbstractA photoactivated liposome release system that is generally applicable for triggered release of encapsulated hydrophilic materials is described. This approach to phototriggered release, derived from the known effects of plasmalogen photooxidation on membrane permeability in whole cells and model membrane systems, relies on producing a lamellar phase change or increase in permeability upon cleaving its constitutive lipids to single-chain surfactants using 630–820 nm light to sensitive the photooxidation of the plasmalogen vinyl ether linkage. Semi-synthetic plasmenylcholine liposomes containing encapsulated calcein and a membrane-bound sensitizer, such as zinc phthalocyanine, tin octabutoxyphthalocyanine, or bacteriochlorophyll a, were prepared by extrusion. Irradiation of air-saturated liposome solutions enhanced membrane permeability toward calcein and Mn2+, and promoted membrane fusion processes compared to non-irradiated or anaerobic controls. Bacteriochlorophyll a sensitization produced the fastest observed photoinitiated release rate from these liposomes (100% calcein release in less than 20 min; 800 nm irradiation at 300 mW); the observed release rate was two orders of magnitude slower for egg lecithin liposomes prepared and irradiated under identical experimental conditions. Liposome aggregation, interlipidic particle formation, and membrane fusion between adjoining liposomes was observed by31P-NMR, freeze-fracture/freeze-etch TEM, and cryo-TEM as a function of irradiation time. The use of near-infrared sensitizers and the capacity of photolyzed plasmenyl-choline liposomes to undergo membrane fusion processes make photodynamic therapy with these liposome-borne sensitizers an attractive adjunct to biochemical targeting methods
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