Space-Time Transfer Function-Noise Modelling of Rainfall-Runoff Process

An explanatory model class belonging to the family of Space-Time Transfer Function-Noise (STTFN) process is presented. The paper develops a three-stage iterative procedure for building STTFN models of the rainfall-runoff process. Four precipitation and runoff stations located in a watershed in southern Ontario, Canada, sampled at 15-day intervals are used for the numerical analysis. Three STTF models are identified. The model parameters are estimated by the polytope technique, a nonlinear optimization algorithm. Two of the developed space-time models proved adequate in describing the spatio-temporal characteristics of precipitation and runoff time series.     

Involvement of mitophagy-mediated cell death in colon cancer cells by folate-appended methyl-β-cyclodextrin

In recent years, colorectal cancer has gained great attention among various types of cancers. We previously synthesized folate-appended methyl-β-cyclodextrin (FA-M-β-CyD) as a novel autophagic antitumor agent. In this study, to further elucidate the impact of FA-M-β-CyD as an antitumor agent, we evaluated cytotoxic activity and the antiproliferative effect in colon cancer cells and colorectal cancer model mice, respectively. As a result, FA-M-β-CyD showed potent cytotoxic activity in HCT116 cells, a human colon cancer cell line, through folate receptor-α (FR-α)-mediated cellular uptake. In addition, FA-M-β-CyD elicited autophagosome formation and induced mitophagy in HCT116 cells. Importantly, FA-M-β-CyD drastically reduced the number of tumor polyps in colorectal cancer model mice induced by azoxymethane/dextran sodium sulfate after intravenous injections once a week for 4 weeks. These results suggest that FA-M-β-CyD has the antiproliferative effect in the colorectal cancer, due to the FR-α-mediated endocytosis and mitophagy induction.     

An inverse problem in reaction kinetics

In this paper we investigate the problem of extracting information about chemical reactions involving multiple species from the time history of the concentration of each species. The mathematical model of the kinetic system leads to a system of ordinary differential equations. Our focus is to examine whether the species’ concentrations as functions of time are sufficient to determine what chemical reactions, and at what reaction rates, have occurred. We show that within the limitation of our model, there may be many candidate reaction systems that could explain the data. Using the notion of sparsity, we provide a quantitative assessment of the question of distinguishability. We further demonstrate that sparsity enforcing approaches, such as minimizing the ℓ ₁ or the ℓ ₀ norms are not reliable. Our conclusion is that additional knowledge about the kinetic system will be necessary to reliably solve this inverse problem.     

QUALITATIVE STUDY FOR A CUBIC SYSTEM

This article analyses a non-Lienard type planar cubic system, and a complete qualitative analysis is given for the system, especially the conclusions for the non-existence, existence and uniqueness of limit cycles are obtained.     

(Ⅲ)m=0类二次系统的极限环问题(Ⅲ)

§1Introduction Continuingthestudyofpapers[1]and[2],weconsideraquadraticsystemofYe's type()systemwithm=0.Withoutlossofgenerality,wemayassumethatb=-1anda<0,thenthesystemtobeconsideredbecomes dx dt=-y+δx+lx2+ny2,dydt=x(1+ax-y).(1)Paper[1]studiedthecases00andn>1,l<0,aswellasthe case01/2forwhichZhanghaveprovedtheuniquenessoflimitcyclesin[7],andpaper[2]discussedthecasen<0,01/2andn>1,l>0,whichwillbediscussedinthispape res…     

On complete recovery of geophysical data

One considers an elastic halfspace with depth (x₁) dependent density Q and Lamé moduli (λ,m?). Impulsive stresses τli = δ(x₂, x₃)δ(t) for x₁ = 0 are applied with displacement responses u_i = g_i(t, x₂, x₃) at x₁ = 0 (i = 1, 2, 3). Let v_i(t, x₁) = ∫∫u_idx₂dx₃ (i = 1, 2 is enough) and set w(t, x₁) = ∫∫x₂u₁dx₂dx₃. One obtains a system of 3 differential equations for v₁, v₂, and w to which the spectral techniques of inverse scattering theory are applied as in [25]. The inverse problems for the uncoupled v_i can then be solved to produce 2 functions A₁ and A₂ involving (Q, λ, μ) as functions of “bound” variables y₁ and y₂ containing (Q, λ, μ), between which a relation then is determined. Analysis of the coupled equation for w then leads to a Fredholm integral equation whose solution provides an additional relation between (Q, λ, μ) from which (Q, λ, μ) can be determined as functions of x₁. The integral equation is reduced to a Volterra type equation by results and techniques of transmutation and then solved by a modification of standard techniques. A number of features and results of independent mathematical interest arise from the transmutation theory.     

Design,Microwave-Assisted Synthesis and In Silico Prediction Study of Novel Isoxazole Linked Pyranopyrimidinone Conjugates as New Targets for Searching Potential Anti-SARS-CoV-2 Agents

A series of novel naphthopyrano[2,3-d]pyrimidin-11(12H)-one containing isoxazole nucleus 4 was synthesized under microwave irradiation and classical conditions in moderate to excellent yields upon 1,3-dipolar cycloaddition reaction using various arylnitrile oxides under copper(I) catalyst. A one-pot, three-component reaction, N-propargylation and Dimroth rearrangement were used as the key steps for the preparation of the dipolarophiles3. The structures of the synthesized compounds were established by ¹H NMR, ¹³C NMR and HRMS-ES means. The present study aims to also predict the theoretical assembly of the COVID-19 protease (SARS-CoV-2 M^pro) and to discover in advance whether this protein can be targeted by the compounds 4a–1 and thus be synthesized. The docking scores of these compounds were compared to those of the co-crystallized native ligand inhibitor (N3) which was used as a reference standard. The results showed that all the synthesized compounds (4a–l) gave interesting binding scores compared to those of N3 inhibitor. It was found that compounds 4a, 4e and 4i achieved greatly similar binding scores and modes of interaction than N3, indicating promising affinity towards SARS-CoV-2 M^pro. On the other hand, the derivatives 4k, 4h and 4j showed binding energy scores (−8.9, −8.5 and −8.4 kcal/mol, respectively) higher than the M^pro N3 inhibitor (−7.0 kcal/mol), revealing, in their turn, a strong interaction with the target protease, although their interactions were not entirely comparable to that of the reference N3.     

Smart Coating Based on Urea-Formaldehyde Microcapsules Loaded with Benzotriazole for Corrosion Protection of Mild Steel in 3.5 % NaCl

Urea-formaldehyde (UF) microcapsules loaded with linseed oil (LO) and benzotriazole (BTA) as core materials have been synthesized by in situ emulsion polymerization. The capsules were characterized by FTIR spectroscopy and particle size analysis. Surface morphology of the microcapsules was analyzed using scanning electron microscopy (SEM). The microcapsules were incorporated into epoxy resin and coated on a mild steel substrate to form a corrosion resistant organic coating. The self-healing property of coatings loaded with different weight % of microcapsules containing LO + BTA was tested by immersion of the UF coated mild steel specimens in 3.5 wt % NaCl solution. It was analyzed through visual inspection, weight loss measurements, and SEM of the scribed region of coating. It was observed that the addition of microcapsules enhances the corrosion resistance of the scratched samples.