697 research outputs found
The hormonal composition of follicular fluid and its implications for ovarian cancer pathogenesis
Ovulation has long been associated with an increased risk in ovarian cancer, yet the underlying molecular mechanisms remain obscure. Two aspects of ovulation have been linked to ovarian cancer pathogenesis. The first is the impact of repetitive tissue injury and repair that occurs with each ovulatory event. The second is the release of follicular fluid that accompanies the follicular rupture and its effect on the ovarian and fallopian tube epithelial cells. Hormones are an important component of follicular fluid, which transiently bathes the ovarian surface and fallopian tube epithelium during ovulation. Much work has been done exploring the role of hormones in fertility, but some, such as estrogen, have also been implicated in the pathogenesis of ovarian and other cancers. Understanding the role of hormones within follicular fluid, as well as how they are altered in disorders which increase ovarian cancer risk, will enhance our ability to assess risk and develop preventative strategies. This review provides an in depth discussion of the logistics of using and studying follicular fluid in ovarian cancer research, and discusses the fluctuations in follicular fluid hormone levels during normal physiological processes versus conditions that increase ovarian cancer risk
Metolazone compound as corrosion inhibitor for API 5L X-52 steel in hydrochloric acid solution
The aim of this research is to evaluate the inhibitive effect of metolazone on API 5L X-52 steel in 2 M HCl solution using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization techniques within a temperature range of 303 to 323 K. Scanning electron microscopy (SEM) was also employed to study the morphology of the corroded coupons in 2 M HCl solution and in the presence of the inhibitor. The efficiency of the inhibition depends on the concentration of metolazone and reaction system temperature. The maximum inhibition efficiency values were 92.7 and 90.7%, respectively, for both EIS and polarization techniques at the temperature of 303 K. The electrochemical impedance spectra (EIS) studies reveal that the process of inhibition is through charge transfer. Potentiodynamic polarization (PDP) studies showed that metolazone is mixed-type inhibitor. The metolazone adsorption characteristics on API 5L X-52 steel surface was found to be spontaneous and obeyed Langmuir adsorption isotherm and the mechanism of adsorption suggest chemisorptions. The inhibition efficiency of metolazone drug obtained by electrochemical methods was in good relationship with each other.
KEY WORDS: Metolazone drug, API 5L X-52 Steel, SEM, Electrochemical, Corrosion inhibition
Bull. Chem. Soc. Ethiop. 2020, 34(2), 407-418
DOI: https://dx.doi.org/10.4314/bcse.v34i2.1
Cystatins as calpain inhibitors: Engineered chicken cystatin- and stefin B-kininogen domain 2 hybrids support a cystatin-like mode of interaction with the catalytic subunit of μ-calpain
Within the cystatin superfamily, only kininogen domain 2 (KD2) is able to inhibit μ- and m-calpain. In an attempt to elucidate the structural requirements of cystatins for calpain inhibition, we constructed recombinant hybrids of human stefin B (an intracellular family 1 cystatin) with KD2 and Delta L110 deletion mutants of chicken cystatin-KD2 hybrids. Substitution of the N-terminal contact region of stefin B by the corresponding KD2 sequence resulted in a calpain inhibitor of K-i = 188 nM. Deletion of L110, which forms a beta -bulge in family 1 and 2 cystatins but is lacking in KD2, improved inhibition of mu -calpain 4- to 8-fold. All engineered cystatins were temporary inhibitors of calpain due to slow substrate-like cleavage of a single peptide bond corresponding to Gly9-Ala10 in chicken cystatin. Biomolecular interaction analysis revealed that, unlike calpastatin, the cystatin-type inhibitors do not bind to the calmodulin-like domain of the small subunit of calpain, and their interaction with the mu -calpain heterodimer is completely prevented by a synthetic peptide comprising subdomain B of calpastatin domain 1. Based on these results we propose that (i) cystatin-type calpain inhibitors interact with the active site of the catalytic domain of calpain in a similar cystatin-like mode as with papain and (ii) the potential for calpain inhibition is due to specific subsites within the papain-binding regions of the general cystatin fold
An Advanced Control Strategy for the Evaporation Section of An Integrated First- and Second-Generation Ethanol Sugarcane Biorefinery
The sugarcane crushing stage is one of the most important technologies being developed at the moment. In this paper, the control of the multiple-stage evaporation system was addressed, as it is a crucial stage in the first- and second-generation ethanol production from sugarcane. A neural network model was proposed based on a dynamic phenomenological model developed in EMSO (Environment for Modeling, Simulation and Optimization). The phenomenological model was used to build a neural network prediction model for an MPC (Model Predictive Control) scheme using a DMC (Dynamic Matrix Control) algorithm. Simulations were carried out to evaluate the performance for tracking the set-point.
Also, disturbance rejection tests were performed, considering different step disturbances. The analysis demonstrated that the MPC scheme performed well in the tests and showed superiority when compared to classical PID controllers.
This work is licensed under a Creative Commons Attribution 4.0 International License
Electron-phonon relaxation and excited electron distribution in zinc oxide and anatase
We propose a first-principle method for evaluations of the time-dependent
electron distribution function of excited electrons in the conduction band of
semiconductors. The method takes into account the excitations of electrons by
external source and the relaxation to the bottom of conduction band via
electron-phonon coupling. The methods permits calculations of the
non-equilibrium electron distribution function, the quasi-stationary
distribution function with steady-in-time source of light, the time of setting
of the quasi-stationary distribution and the time of energy loss via relaxation
to the bottom of conduction band. The actual calculations have been performed
for titanium dioxide in the anatase structure and zinc oxide in the wurtzite
structure. We find that the quasi-stationary electron distribution function for
ZnO is a fermi-like curve that rises linearly with increasing excitation energy
whereas the analogous curve for anatase consists of a main peak and a shoulder.
The calculations demonstrate that the relaxation of excited electrons and the
setting of the quasi-stationary distribution occur within the time no more than
500 fsec for ZnO and 100 fsec for anatase.
We also discuss the applicability of the effective phonon model with
energy-independent electron-phonon transition probability. We find that the
model only reproduces the trends in changing of the characteristic times
whereas the precision of such calculations is not high. The rate of energy
transfer to phonons at the quasi-stationary electron distribution also have
been evaluated and the effect of this transfer on the photocatalyses has been
discussed. We found that for ZnO this rate is about 5 times less than in
anatase.Comment: 21 p., 9 figure
Bidirectional light-scattering image processing method for high-concentration jet sprays
In order to study the distributions of droplet size and volume density in high-concentration jet sprays, a new technique is developed, which combines the forward and backward light scattering method and an image processing method. A pulsed ruby laser is used as the light source. The Mie scattering theory is applied to the results obtained form image processing on the scattering photographs. The time history is obtained for the droplet size and volume density distributions, and the method is demonstrated by diesel fuel sprays under various injecting conditions. The validity of the technique is verified by a good agreement in the injected fuel volume distributions obtained by the present method and by injection rate measurements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25819/1/0000382.pd
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