(2Z,2′Z,4E,4′E)-4,4′-(Cyclo­hexane-1,2-diyldinitrilo)dipent-2-en-2-ol

A new tetra­dentate chiral Schiff base ligand, C16H26N2O2, has been synthesized by the reaction of acetyl­acetone with (1R,2R)-(−)-1,2-diamino­cyclo­hexane. Both of the mol­ecules in the asymmetric unit are of the same chirality (R configuration), since the absolute configuration was determined by the starting reagent (1R,2R)-(−)-1,2-diamino­cyclo­hexane. The six-membered cyclo­hexane ring is in a chair conformation, and the substituents are equatorial in the most stable conformation (trans-cyclo­hexyl). At the ring substituents, large conjugated —C=N—CH=C—OH systems exist, resulting from the original ketone converted into the enol form. With H atoms excluded, the atoms of each substituent lie in the same plane. The two mol­ecules in the asymmetric unit have almost the same structure, with slight differences in the torsion angles between the substituents and the cyclo­hexane ring; the corresponding N1—(C—C—C)cyclo­hexa­ne torsion angles are −177.2 (3) and 179.3 (4)° in one mol­ecule and −176.5 (3) and 178.4 (4)° in the other. Two intra­molecular O—H⋯N hydrogen bonds exist in each mol­ecule

Singularities and Accumulation of Singularities of π\piN Scattering amplitudes

It is demonstrated that for the isospin $I=1/2$ $\pi$N scattering amplitude, $T^{I=1/2}(s,t)$, $s={(m_N^2-m_\pi^2)^2}/{m_N^2}$ and $s=m_N^2+2m_\pi^2$ are two accumulation points of poles on the second sheet of complex $s$ plane, and are hence accumulation of singularities of $T^{I=1/2}(s,t)$. For $T^{I=3/2}(s,t)$, $s={(m_N^2-m_\pi^2)^2}/{m_N^2}$ is the accumulation point of poles on the second sheet of complex $s$ plane. The proof is valid up to all orders of chiral expansions.Comment: 6 pages, one reference added, a bug removed, major conclusions remain unchange

2-Carb­oxy-1-phenyl­ethanaminium perchlorate

In the title compound, C9H12NO2 +·ClO4 −, an intra­molecular N—H⋯O inter­action results in the formation of a six-membered ring having a twisted chair conformation. In the crystal structure, inter­molecular O—H⋯O, N—H⋯O and C—H⋯O inter­actions link the mol­ecules into a network. A weak C—H⋯π inter­action is also found

A possible subthreshold pole in S11S_{11} channel from πN\pi N Roy-Steiner equation analyses

The hyperbolic version of Roy-Steiner equation describing low energy $\pi N$ scatterings, with larger analyticity domain in the complex $s$ plane is solved. The numerical results on phase shifts of low partial waves are in agreement with that of Hoferichter et al. [Phys. Rept. 625 (2016) 1]. A subthreshold pole in $S_{11}$ channel is found located at $\sqrt{s}=(918 \pm 3)-i (163 \pm 9)$~MeV.Comment: 12 pages, 4 figures; Minor improvements in numerical results and discussions, conclusions unchanged, final version to appear in JHE

The Effect of Microclimates in the Aeolian Sand Environment at the Mogao Grottoes, China

To study the micro-meteorological effects of different underlying surfaces of structures to protect the Mogao Grottoes, we analyzed basic meteorological measurements collected at weather stations located in front of the grottoes, on top of the grottoes and in the artificial Gobi. The results show that the shelterbelts in front of the grottoes have a heat-retaining effect. The profile of average daily solar radiation in front of the grottoes forms a sharp peak and the profile in the Gobi forms a parabola, but these patterns vary in different seasons. The artificial Gobi was more susceptible to extremes in temperature and had a faster response and wider response range to ground temperature. The average monthly air temperature, average monthly relative humidity, and the average wind speed in the artificial Gobi tend to first decrease and then increase with measurement height

Flow and heat transfer in metal foam filled pipes under two extended Darcy models

The flow and heat transfer in pipes filled with metal foams were studied numerically.In this study,the two-equation model based on LNTE (Local Non-Thermal equilibrium) was employed as energy equations,furthermore the flow models extended by Brinkman and Brinkman-Forchheimer were employed as momentum equations respectively,and a comparison between these two models was made and analysed.The numerical results indicate that the velocity profiles under two models are different,but their temperature profiles are almost the same as each other,consequently,there are barely differences between the Nu numbers under two models.According to numerical results,the Nu number of metal-foam filled pipes is of the order of magnitude of 102～103,which is much bigger than that of bare pipes and conventional heat exchangers.The metal-foam filled pipes exhibit excellent heat transfer performance,however high pressure drop is produced at the same time.By using the program for heat transfer calculation of metal foam that is developed by us,someone can make optimization of heat transfer and pressure drop in practical applications

Poly[diaqua-1κ2 O-bis[μ3-2-(1H-tetra­zol-5-yl)benzoato(2−)]dicadmium(II)]

The title compound, [Cd2(C8H4N4O2)2(H2O)2]n, is a coordination polymer prepared by the hydro­thermal reaction of cadmium(II) chloride and 2-(1H-tetra­zol-5-yl)benzoic acid. Two types of coordinated cadmium cations exist in the structure. One is located on a twofold axis and is coordinated by four O and two N atoms from four symmetry-related ligands, forming a trigonal-prismatic coordination polyhedron. The other is located on an inversion center and is octa­hedrally coordinated by two N and two O atoms from two ligands in equatorial sites, and two water mol­ecules in axial sites. The organic ligand bridges three Cd atoms, through a carboxyl­ate group and two N atoms of the tetra­zolate unit. This mode of coordination results in a two-dimensional framework. The crystal structure is stabilized by inter­molecular O—H⋯O and O—H⋯N hydrogen bonds

(1Z,1′Z,3E,3′E)-1,1′-Diphenyl-3,3′-[(1S,2S)-cyclo­hexane-1,2-diyldinitrilo]dibut-1-en-1-ol

A new tetra­dentate chiral Schiff base ligand, C26H30N2O2, has been synthesized by the reaction of 1-phenyl­butane-1,3-dione with (1S,2S)-(−)-1,2-diamino­cyclo­hexane. The chiral centers in the mol­ecule have the same S configuration, since the absolute configuration was determined by that of the starting reagent (1S,2S)-(−)-1,2-diamino­hexane. The cyclo­hexane ring is in a chair conformation, and the substituents are equatorial in the most stable conformation (trans-cyclo­hexyl). The crystal structure is stabilized by two intra­molecular O—H⋯N hydrogen bonds and a weak C—H⋯π inter­action