On the Renormalization of the One–Pion Exchange Potential and the Consistency of Weinberg’s Power Counting

Nogga, Timmermans and van Kolck recently argued that Weinberg’s power counting in the few–nucleon sector is inconsistent and requires modifications. Their argument is based on the observed cutoff dependence of the nucleon–nucleon scattering amplitude calculated by solving the Lippmann–Schwinger equation with the regularized one–pion exchange potential and the cutoff Λ varied in the range Λ = 2 . . . 20 fm^?1. In this paper we discuss the role the cutoff plays in the application of chiral effective field theory to the two–nucleon system and study carefully the cutoff–dependence of phase shifts and observables based on the one–pion exchange potential. We show that (i) there is no need to use the momentum–space cutoff larger than Λ ~ 3 fm^?1; (ii) the neutron–proton low–energy data show no evidence for an inconsistency of Weinberg’s power counting if one uses Λ ~ 3 fm^?1.     

Measurement and analysis of fission rates in a spherical mockup of uranium and polyethylene

Measurements of the reaction rate distribution were carried out using two kinds of Plate Micro Fission Chamber （PMFC）. The first is a depleted uranium chamber and the second an enriched uranium chamber. The material in the depleted uranium chamber is strictly the same as the material in the uranium assembly. With the equation solution to conduct the isotope contribution correction, the fission rate of 238U and 235U were obtained from the fission rate of depleted uranium and enriched uranium. Then, the fission count of 238U and 235U in an individual uranium shell was obtained. In this work, MCNP5 and continuous energy cross sections ENDF/BV.0 were used for the analysis of fission rate distribution and fission count. The calculated results were compared with the experimental ones. The calculation of fission rate of DU and EU were found to agree with the measured ones within 10% except at the positions in polyethylene region and the two positions near the outer surface. Because the fission chamber was not considered in the calculation of the fission counts of 238U and 235U, the calculated results did not agree well with the experimental ones.     

Linear spaces and preservers of symmetric matrices of bounded rank-two

Let 𝔽 be a field of characteristic two. Let S _n (𝔽) denote the vector space of all n?×?n symmetric matrices over 𝔽. We characterize i. subspaces of S _n (𝔽) all whose elements have rank at most two where n???3,

ii. linear maps from S _m (𝔽) to S _n (𝔽) that sends matrices of rank at most two into matrices of rank at most two where m, n???3 and |𝔽|?≠?2.

     

The removal of MO molecules from aqueous solution by the combination of ultrasound/adsorption/photocatalysis

Methyl orange (MO) molecules had been removed from aqueous solution by nano-TiO(2)/exfoliated graphite composites with the combination of ultrasound/adsorption/photocatalysis. The experimental results had showed that nano-TiO(2)/exfoliated graphite composites provided with the adsorptive capability of exfoliated graphite and the photocatalysis capability of nano-TiO(2) synchronously. It had been proved that the removal ratios related to the adsorption and photocatalysis capability of the composites and were influenced by US and UV irradiation, the reaction times, the reaction temperatures, the initial pH values, the dosages and the initial MO solution concentrations. Moreover, it had been illuminated that the combination was very effective and useful on removing MO molecules from aqueous solution.     

Synthesis and Crystal Structure of Diisopropyl Hydroxy(4-methoxyphenyl)methylphosphonate

Abstract  The title compound, C₁₄H₂₃O₅P, was synthesized by the reaction of 4-methoxybenzaldehyde and diisopropyl phosphite. Its structure was determined with X-ray crystallographic, NMR, MS, and elemental analysis (EA) techniques. The crystal belongs to monoclinic, space group P 2_1/n with the following crystallographic parameters: a = 10.529 (2) ?, b = 8.424 (2) ?, c = 19.448 (4) ?, α = 90°, β = 105.2 (3)°, γ = 90°, μ = 0.180 mm⁻¹, V = 1664.1 (6) ?³, Z = 4, Dx = 1.207 mg/mm³, F (000) = 648, T = 293 (2) K, 2.00° ≤ θ ≤ 25.50°. The final residual factor is 0.049 for 1933 reflections with I > 2σ (I). Crystal packing is stabilized by interatomic hydrogen bond interactions between the doubly bonded phosphoryl O atom and the hydroxyl H atom which link the molecules into chains along the [011] plane of the unit cell. Index Abstract   The title compound, diisopropyl hydroxy(4-methoxyphenyl)methylphosphonate, was synthesized by the reaction of 4-methoxybenzaldehyde and diisopropyl phosphite. Its structure was determined with X-ray crystallographic, NMR, MS, and elemental analysis (EA) techniques. Crystal packing is stabilized by interatomic hydrogen bond interactions between the doubly bonded phosphoryl O atom and the hydroxyl H atom which link the molecules into chains along the [011] plane of the unit cell.      

Effect of calcination temperature on the photocatalytic activity of carbon‐doped titanium dioxide revealed by photoluminescence study

Carbon‐doped titania (C‐TiO₂) nanoparticles were synthesized by the sol–gel method at different calcination temperatures (300–600°C) employing titanium tetraisopropoxide (TTIP) as the titanium source and polyoxyethylene sorbitan monooleate (Tween 80) as the carbon source. The physical properties of C‐TiO₂ samples were characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activities were checked through the photodegradation of phenolphthalein (PHP) under ultraviolet irradiation. The UV spectrum showed that the carbon doping extends the absorption range of TiO₂ to the visible region. However, the photocatalytic activity is affected by the electron–hole recombination phenomenon, as revealed by the photoluminescence (PL) study. According to the PL spectra, carbon doping reduces the edge‐to‐edge electron–hole recombination. Nevertheless, the number of defect sites is greatly influenced by the calcination temperature of C‐TiO₂. C‐TiO₂ that was calcined at 400°C showed the highest photodegradation percentage of PHP, which was mainly attributed to the synergic effect of the low direct edge‐to‐edge electron–hole recombination, high content of defect sites, and retention of active electrons on the surface hydroxyl group.     

Synthesis and Antitumor Effect of Sophoridine Derivatives Bearing an Acyclic Aryloxy Phosphoramidate Mustard Functionality

To elevate the potency of sophoridine, phosphoramidate mustard motif was incorporated to D‐ring opened sophoridine scaffold. A series of acyclic aryloxy phosphoramidate mustard functionalized sophoridine derivatives were synthesized and screened for cytostatic activity in a range of different tumor cell lines (S180, H22, K562, MCF‐7, SMMC‐7721, and LoVo). All these compounds were shown to be more sensitive to S180 and H22 cells with IC₅₀ values ranging from 2.10 to 7.21 μM. In addition, all targeted derivatives distinctly are more cytotoxic to cancer cells than normal cell L929. Compounds 8b , 8c , 8d , and 8e displayed moderate tumor suppression without apparent organ toxicity in vivo against mice bearing H22 liver tumors. Their potential binding modes with DNA topoisomerase I complex have also been investigated.     

Design,Synthesis, and Antifungal Activity of 3‐(Thiophen‐2‐yl)‐1,5‐dihydro‐2H‐pyrrol‐2‐one Derivatives Bearing a Carbonic Ester Group

A series of 3‐(thiophen‐2‐yl)‐1,5‐dihydro‐2H‐pyrrol‐2‐one derivatives bearing a carbonic ester group were designed and synthesized by integrating a thiophene nucleus and a pyrroline‐2‐one scaffold in a single molecular architecture. Their structures were confirmed by IR, ¹H‐NMR, EI‐MS, and elemental analyses, and their antifungal activities against Fusarium graminearum (Fg), Rhizoctorzia solani (Rs), and Botrytis cinerea (Bc) were evaluated. The antifungal bioassays indicated that some title compounds exhibited desirable antifungal effects against the tested fungi. Strikingly, the title compounds 4i , 4k , 4n , and 4o showed obvious antifungal activities against Rs, with corresponding EC₅₀ values of 35.26, 33.56, 23.90, and 30.48 μg/mL, respectively, which are better than that of hymexazol (37.86 μg/mL). These results indicated that 3‐(thiophen‐2‐yl)‐1,5‐dihydro‐2H‐pyrrol‐2‐one derivatives bearing a carbonic ester group can serve as potential structural templates in the search for novel high‐efficient fungicides.     

A New Planar Hexanuclear Dysprosium Cluster Exhibiting Slow Magnetic Relaxation Features

Reaction of the Schiff base ligand H₂L and dysprosium acetate result in a new planar Dy₆ cluster [Dy₆(μ₃‐OH)L₆(Ac)₆] · MeOH ( 1 ) [H₂L = N'‐(2‐hydroxybenzylidene)‐2‐(hydroxyimino)propanohydrazide, HAc = acetic acid], which was successfully structurally and magnetically characterized. Single‐crystal X‐ray diffraction analysis revealed that 1 contained a hexanuclear dysprosium cluster [Dy₆], which is composed of four Dy₃ triangular units. Magnetic measurements suggest that 1 displays single‐molecule magnet (SMM) behavior which is enhanced by applying a 4000 Oe direct‐current field. The effective anisotropic barrier U_eff/k_B = 14.9 K and the pre‐exponential factor τ₀ = 1.31 × 10^–6 s are also obtained. This work may provide more insights for the design and investigation of lanthanide‐based SMMs.     

Chemical Protein Synthesis Enabled Mechanistic Studies on the Molecular Recognition of K27‐linked Ubiquitin Chains

New synthetic strategies that exploited the strengths of both chemoselective ligation and recombinant protein expression were developed to prepare K27 di‐ubiquitins (diUb), which enabled mechanistic studies on the molecular recognition of K27‐linked Ubs by single‐molecule Förster resonance energy transfer (smFRET) and X‐ray crystallography. The results revealed that free K27 diUb adopted a compact conformation, whereas upon binding to UCHL3, K27 diUb was remodeled to an open conformation. The K27 isopeptide bond remained rigidly buried inside the diUb moiety during binding, an interesting unique structural feature that may explain the distinctive biological function of K27 Ub chains.