Dark Energy with Phantom Crossing and the H0 Tension

We investigate the possibility of phantom crossing in the dark energy sector and the solution for the Hubble tension between early and late universe observations. We use robust combinations of different cosmological observations, namely the Cosmic Microwave Background (CMB), local measurement of Hubble constant (H0), Baryon Acoustic Oscillation (BAO) and SnIa for this purpose. For a combination of CMB+BAO data that is related to early universe physics, phantom crossing in the dark energy sector was confirmed at a 95% confidence level and we obtained the constraint H0=71.0−3.8+2.9 km/s/Mpc at a 68% confidence level, which is in perfect agreement with the local measurement by Riess et al. We show that constraints from different combinations of data are consistent with each other and all of them are consistent with phantom crossing in the dark energy sector. For the combination of all data considered, we obtained the constraint H0=70.25±0.78 km/s/Mpc at a 68% confidence level and the phantom crossing happening at the scale factor am=0.851−0.031+0.048 at a 68% confidence level.     

Nickel tetrathiooxalate as a cathode material for potassium batteries

We report a nickel tetrathiooxalate (NiTTO) coordination polymer as a cathode material for potassium batteries. In a potential range of 1.3–3.6 V vs. K⁺/K, the specific capacity of the material is 209 mA h g^?1 at a current density of 0.1 A g^?1, which roughly corresponds to the two-electron reduction of polymer repeating units. The charge–discharge mechanisms of NiTTO in potassium cells were examined using operando Raman spectroscopy.     

Portable single-sided NMR measurements at variable temperatures: Implementation of a thermo-controlled device and application to the heating of bread dough

A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample.     

Spectroscopic properties and bond dissociation energies of PbX,PbX±, PbX2 and PbX2± (X ​= ​F,Cl, Br,I)

Ab initio calculations have been performed to investigate some of the spectroscopic properties, like geometry, frequency, electron affinity, ionization potential and finally adiabatic bond dissociation energies (BDEs) of lead monohalides, lead dihalides and their ions viz. PbX, PbX^±, PbX₂, $\mathrm{P}\mathrm{b}{\mathrm{X}}_{\mathrm{2}}^{\pm }$ (X ?= ?F, Cl, Br, I) in their ground state at the QCISD(T)//MP2 level of theory using correlation consistent basis sets. For the validation of MP2 optimized geometry and frequency, we further obtained geometry and frequency of all the neutral and ionic systems using QCISD(T) method with the same basis sets. The BDEs of PbX₂ molecules are calculated using the BDEs of $\mathrm{P}\mathrm{b}{\mathrm{X}}_{\mathrm{2}}^{\pm }$ ions and taking ionization potential and electron affinity of various systems. The calculated values are found in good agreement with the available data. Most of the data for ionic systems are reported first time in literature.     

Visible-Light Augmented Lithium Storage Capacity in a Ruthenium(II) Photosensitizer Conjugated with a Dione-Catechol Redox Couple

Controlling redox activity of judiciously appended redox units on a photo-sensitive molecular core is an effective strategy for visible light energy harvesting and storage. The first example of a photosensitizer - electron donor coordination compound in which the photoinduced electron transfer step is used for light to electrical energy conversion and storage is reported. A photo-responsive Ru-diimine module conjugated with redox-active catechol groups in [Ru(II)(phenanthroline-5,6-diolate)₃]⁴⁻ photosensitizer can mediate photoinduced catechol to dione oxidation in the presence of a sacrificial electron acceptor or at the surface of an electrode. Under potentiostatic condition, visible light triggered current density enhancement confirmed the light harvesting ability of this photosensitizer. Upon implementation in galvanostatic charge-discharge of a Li battery configuration, the storage capacity was found to be increased by 100 %, under 470 nm illumination with output power of 4.0 mW/cm⁻². This proof-of-concept molecular system marks an important milestone towards a new generation of molecular photo-rechargeable materials.     

Global existence and time decay of the non-cutoff Boltzmann equation with hard potential

This paper is concerned with the Cauchy problem on the Boltzmann equation without angular cutoff assumption for hard potential in the whole space. When the initial data is a small perturbation of a global Maxwellian, the global existence of solution to this problem is proved in unweighted Sobolev spaces $H^N\left({\mathbb{R}}_{x,v}^6\right)$ with $N\ge 2$. But if we want to obtain the optimal temporal decay estimates, we need to add the velocity weight function, in this case the global existence and the optimal temporal decay estimate of the Boltzmann equation are all established. Meanwhile, we further gain a more accurate energy estimate, which can guarantee the validity of the assumption in Chen et al. (0000).     

现代分析仪器在高中化学教学中的应用*——以“防晒霜的防晒效果实验探究”为例

从高中化学原子、分子等抽象性的知识教学出发,以防晒霜的防晒效果实验探究为例,探讨了现代分析仪器在高中化学教学中的应用。通过利用现代分析仪器紫外可见分光光度计,结合紫外线变色球实验探究防晒霜的防晒效果,分析并认识防晒霜中化学防晒的机理。结果表明,防晒霜的厚度越大、SPF越高,防晒霜的防晒效果越好,并且防晒霜的防晒效果可以持续一段时间,但是不同类型的防晒产品存在一定差异。在化学教学中渗透现代分析仪器的应用,为学生进一步了解化学学科在改变学习方式、拓宽学科知识领域、推动自身全面与可持续发展方面打下坚实的基础。     

关于两个图的一类新连接图的谱

给定2个图G1和G2，设G1的边集E(G1)={e1,e2,?,em1}，则图G1⊙G2可由一个G1，m1个G2通过在G1对应的每条边外加一个孤立点，新增加的点记为U={u1,u2,?,um1}，将ui分别与第i个G2的所有点以及G1中的边ei的端点相连得到，其中i=?1,2,?,m1。得到：（i）当G1是正则图，G2是正则图或完全二部图时，确定了G1⊙G2的邻接谱（A-谱）。（ii）当G1是正则图，G2是任意图时，给出了G1⊙G2的拉普拉斯谱（L-谱）。（iii）当G1和G2都是正则图时，给出了G1⊙G2的无符号拉普拉斯谱（Q-谱）。作为以上结论的应用，构建了无限多对A-同谱图、L-同谱图和Q-同谱图；同时当G1是正则图时，确定了G1⊙G2支撑树的数量和Kirchhoff指数。     

Efficient Piezoelectric Energy Harvesting from a Discrete Hybrid Bismuth Bromide Ferroelectric Templated by Phosphonium Cation

Bismuth containing hybrid molecular ferroelectrics are receiving tremendous attention in recent years owing to their stable and non-toxic composition. However, these perovskite-like structures are primarily limited to ammonium cations. Herein, we report a new phosphonium based discrete perovskite-like hybrid ferroelectric with a formula [Me(Ph)₃P]₃[Bi₂Br₉] ( MTPBB ) and its mechanical energy harvesting capability. The Polarization-Electric field (P-E) measurements resulted in a well-defined ferroelectric hysteresis loop with a remnant polarization value of 2.1 μC cm⁻². Piezoresponse force microscopy experiments enabled visualization of the ferroelectric domain structure and evaluation of the piezoelectric strain coefficient (d₃₃) for an MTPBB single crystal and thin film sample. Furthermore, flexible devices incorporating MTPBB in polydimethylsiloxane (PDMS) matrix at various concentrations were fabricated and explored for their mechanical energy harvesting properties. The champion device with 20 wt % of MTPBB in PDMS rendered a maximum peak-to-peak open-circuit voltage of 22.9 V and a maximum power density of 7 μW cm⁻² at an optimal load of 4 MΩ. Moreover, the potential of MTPBB -based devices in low power electronics was demonstrated by storing the harvested energy in various electrolytic capacitors.