Capsaicin, the main ingredient responsible for the hot pungent taste of chilli peppers, is an alkaloid found in the Capsicum family. Capsaicin was traditionally used for muscular pain, headaches, to ...improve circulation and for its gastrointestinal protective effects. It was also commonly added to herbal formulations because it acts as a catalyst for other herbs and aids in their absorption. In addition, capsaicin and other capsaicinoid compounds showed strong evidence of having promising potential in the fight against many types of cancer. The mechanism of action of capsaicin has been extensively studied over the past decade. It has been established that capsaicin binds to the transient receptor potential vanilloid 1 receptor which was expressed predominantly by sensory neurons. And many analogues of capsaicin have been synthesized and evaluated for diverse bioactivities. In this review, we will attempt to summarize the biology and structure-activity relationship of capsaicinoids.
Supernova remnant (SNR) shock waves are the main place where interstellar dust grains are destroyed. However, the dust destruction efficiency in nonradiative shocks is still not well known. One way ...to estimate the fraction of dust destroyed is to compare the difference between postshock gas abundances and preshock medium total abundances when the preshock elemental depletion factors are known. We compare the postshock gas abundances of 16 SNRs in the Large Magellanic Cloud (LMC) with the LMC interstellar medium abundances that we derived based on 69 slow-rotating early B-type stars. We find that, on average, ∼61% of Si-rich dust grains are destroyed in the shock, while the fraction of dust destroyed is only ∼40% for Fe-rich dust grains. This result supports the idea that the high depletion of Fe in the diffuse neutral medium is not caused by the resilience of Fe-rich grains but because of faster growth rate. This work also presents a potential way to constrain the chemical composition of interstellar dust.
A new formulation is developed for dynamic analysis of a rotating planar Timoshenko beam. The configuration of Timoshenko beam is described using its slope angle and axial and shear strains; hence, ...the shear locking problem can be naturally avoided. Nonlinear partial differential equations of the rotating hub–beam system and associated boundary conditions are derived using Hamilton’s principle. While six boundary conditions are needed for choice of trial functions of three dependent variables, there are only four boundary conditions that can be determined and two boundary conditions are undetermined. An accurate global spatial discretization method is used, where dependent variables are divided into internal and boundary-induced terms. Internal terms only need to satisfy homogeneous boundary conditions, which can be easily chosen as trigonometric functions. Boundary-induced terms are interpolated using dependent variables at boundaries that are taken as generalized coordinates. Nonlinear governing ordinary differential equations of the system are obtained using Lagrange’s equations. When the hub rotates at a constant angular velocity, nonlinear governing equations can be linearized for vibration analysis, and dimensionless vibration equations of the beam are obtained. Natural frequencies and mode shapes of the beam with a constant angular velocity are calculated and compared with available results in the literature. Frequency veering and mode shift phenomena occur. Nonlinear dynamic responses of the system are then calculated and compared with those from the commercial software ADAMS, and they are in good agreement. Axial and shear strains of the beam and their spatial derivatives are also calculated. Since trial functions in the assumed modes method cannot satisfy undetermined boundary conditions, inaccurate results of strains and their spatial derivatives are obtained using the assumed modes method. Hence, use of the accurate global spatial discretization method in the current formulation is essential here.
The discrete element method has been used to simulate the particle flow in a ball mill under different operating conditions. The model was validated by comparing the simulated results of the flow ...pattern and input power with those measured from a same-scale laboratory mill. The impact energy of the particles under different operating conditions was analysed in detail. The results showed that the impact energy was affected by the operating conditions of the mill and can be linked to the grinding rate for a given material. The correlation between impact energy and grinding rate follows first-order grinding kinetics. Mill performance decreases with increasing mill size. Furthermore, a data-driven machine learning framework has been proposed to predict the impact energy for different operating conditions. It was found that the prediction for mills with diameters of 2000 and 3000 mm based on the training model developed by mills with diameter less than 254 mm could be achieved with an accuracy of 80% and a correlation coefficient of 0.9. Through the combination of DEM simulation and data-driven approach, the computing time required in the determination of impact energy for large scale mills can be dramatically reduced.
Display omitted
•Large scale grinding rate prediction can be achieved with machine learning.•First-order grinding kinetics exists for ball mills.•A correlation exists between specific impact energy and grinding rate constant.•Grinding efficiency decreases with increasing mill size.
An Australian natural zeolite was collected, characterised and employed for basic dye adsorption in aqueous solution. The natural zeolite is mainly composed of clinoptiloite, quartz and mordenite and ...has cation-exchange capacity of 120
meq/100
g. The natural zeolite presents higher adsorption capacity for methylene blue than rhodamine B with the maximal adsorption capacity of 2.8
×
10
−5 and 7.9
×
10
−5
mol/g at 50
°C for rhodamine B and methylene blue, respectively. Kinetic studies indicated that the adsorption followed the pseudo second-order kinetics and could be described as two-stage diffusion process. The adsorption isotherm could be fitted by the Langmuir and Freundlich models. Thermodynamic calculations showed that the adsorption is endothermic process with Δ
H° at 2.0 and 8.7
kJ/mol for rhodamine B and methylene blue. It has also found that the regenerated zeolites by high-temperature calcination and Fenton oxidation showed similar adsorption capacity but lower than the fresh sample. Only 60% capacity could be recovered by the two regeneration techniques.
Six digested sludges, pre-treated by different methods (heat-shock, aeration, acid and base treatments, 2-bromoethanesulfonic acid (BESA) inhibition and iodopropane inhibition) as well as an ...untreated sample were compared for their suitability in the preparation of hydrogen producing seeds by cultivations in a sucrose medium. The heat-shock and acid treatment methods completely repressed methanogenic activity; however, they also partially repressed hydrogen production. The base treatment option did not completely repress methanogenic activity and also significantly impacted hydrogen production. The aeration method was unsuccessful at completely repressing methanogenic activity; however, it did not significantly affect the hydrogen production activity. The BESA and iodopropane pre-treatment methods specifically inhibited the methanogens, and there were no significant effects found on hydrogen production. Similar to the aeration pre-treated digested sludge sample, the untreated sludge showed high hydrogen production activity and a small amount of methanogenic activity (lower than the activity detected in the base treatment sample). In the subsequent second-step batch cultivations with the same sucrose medium and the diluted media, methanogenic activity was not detected in any of the test bottles. The microbial seed prepared from base treatment exhibited the highest hydrogen production activity, whereas those prepared from acid treatment did not exhibit any activity. Again, the microbial seed prepared from untreated sludge also exhibited relatively high hydrogen producing activity. A lower pH was detected at the end of the cultivation in all the test bottles. Interestingly, the variations in pH in the different tests bottles indicate that pH is an important parameter in the control of methanogenic activity.
Although various cosmological observations congruously suggest that our universe is dominated by two dark components, the cold dark matter without pressure and the dark energy with negative pressure, ...the nature and origin of these components is yet unknow. The generalized Chaplygin gas (gCg), parametrized by an equation of state, $p = -A/\rho_{\rm gCg}^{\alpha}$, was recently proposed to be a candidate of the unified dark matter/energy (UDME) scenarios. In this work, we investigate some observational constraints on it. We mainly focus our attention on the constraints from recent measurements of the X-ray gas mass fractions in clusters of galaxies published by Allen et al. (CITE, MNRAS, 334, L11; CITE, 342, 257) and the dimensionless coordinate distances to type Ia supernovae and Fanaroff-Riley type IIb radio galaxies compiled by Daly & Djorgovski (CITE, ApJ, 597, 9). We obtain the confidence region on the two parameters fully characterizing gCg, $A_{\rm s} \equiv A/\rho_{{\rm gCg}0}^{(1+\alpha)}$ and α, from a combined analysis of these databases, where $\rho_{{\rm gCg}0}$ is the energy density of gCg at present. It is found that $A_{\rm s}=0.70^{+0.16}_{-0.17}$ and $\alpha=-0.09^{+0.54}_{-0.33}$, at a 95% confidence level, which is consistent within the errors with the standard dark matter + dark energy model, i.e., the case of $\alpha = 0$. Particularly, the standard Chaplygin gas ($\alpha=1$) is ruled out as a feasible UDME by the data at a 99% confidence level.
Gas hydrate formation experiments were performed using methane in the presence of tetrahydrofuran (THF) in aqueous solution in a transparent bubble column in which a single pipe or a sintered plate ...was used to produce bubbles. The mole fraction of THF in aqueous solution was fixed at 6%. The hydrate formation kinetic behaviors on the surface of the rising bubble, the mechanical stability of hydrate shell formed on the surface of the bubble, the interactions among the bubbles with hydrate shell were observed and investigated morphologically. The rise velocities of individual bubbles with hydrate shells of different thickness and the consumption rates of methane gas were measured. A kinetic model was developed to correlate the experimentally measured gas consumption rate data. It was found that the hydrate formation rate on the surface of the moving bubble was high, but the formed hydrate shell was not very easy to be broken up. The bubbles with hydrate shells tended to agglomerate rather than merge into bigger bubble. This kind of characteristic of hydrate shell hindered the further formation of hydrate and led to the lower consumption rate of methane. The consumption rate of methane was found to increase with the decrease of temperature or increase of pressure. The increase of gas flux led to a linear increase in consumption rate of methane. It was demonstrated that the developed kinetic model could be used to correlate the consumption rate satisfyingly.
In the processes that are used to produce single-walled nanotubes (electric arc, laser ablation, and chemical vapor deposition), the typical lengths of tangled nanotube bundles reach several tens of ...micrometers. We report that long nanotube strands, up to several centimeters in length, consisting of aligned single-walled nanotubes can be synthesized by the catalytic pyrolysis of n-hexane with an enhanced vertical floating technique. The long strands of nanotubes assemble continuously from arrays of nanotubes, which are intrinsically long.
To examine the expression level of HOTAIR in pancreatic β cells. Moreover, regulatory effects of HOTAIR on insulin secretion, proliferation, cell cycle, and apoptosis in β cells are determined.
...HOTAIR levels in mouse primary pancreatic cells and MIN6 cell line were determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Its level was significantly observed in MIN6 cells treated with different doses of glucose. After the knockdown of HOTAIR, insulin secretion, cell cycle distribution, proliferation, and apoptosis in pancreatic β cells were assessed.
HOTAIR was abundantly expressed in pancreatic islets. HOTAIR level in pancreatic tissues of db/db mice was downregulated and influenced by glucose level. Knockdown of HOTAIR attenuated insulin secretion and synthesis capacities in both MIN6 cells and primary pancreatic cells, which may be related by the downregulation of MafA, Pdx1, and NeuroD. Moreover, the silence of HOTAIR suppressed proliferation, arrested cell cycle, and stimulated apoptosis in pancreatic β cells.
HOTAIR is highly expressed in pancreatic tissues. The silence of HOTAIR inhibits insulin secretion by downregulating insulin transcription-related genes. In addition, the silence of HOTAIR suppresses proliferation, arrests cell cycle progression, and induces apoptosis in pancreatic β cells.
PDF
