Photoelectrocatalytic principles for meaningfully studying photocatalyst properties and photocatalysis processes:From fundamental theory to environmental applications

Photocatalysis is critically important for environmental remediation and renewable energy technologies.The ability to objectively characterize photocatalyst properties and photocatalysis processes is paramount for meaningful performance evaluation and fundamental studies to guide the design and development of high-performance photocatalysts and photocatalysis systems.Photocatalysis is essentially an electron transfer process,and photoelectrocatalysis(PEC)principles can be used to directly quantify transferred electrons to determine the intrinsic properties of photocatalysts and photocatalysis processes in isolation,without interference from counter reactions due to physically separated oxidation and reduction half-reactions.In this review,we discuss emphatically the PEC-based principles for characterizing intrinsic properties of photocatalysts and important processes of photocatalysis,with a particular focus on their environmental applications in the degradation of pollutants,disinfection,and detection of chemical oxygen demand(COD).An outlook towards the potential applications of PEC technique is given.

A Review on Metal-and Metal Oxide-Based Nanozymes:Properties,Mechanisms,and Applications

Since the ferromagnetic(Fe_(3)O_(4))nanoparticles were firstly reported to exert enzyme-like activity in 2007,extensive research progress in nanozymes has been made with deep investigation of diverse nanozymes and rapid development of related nanotechnologies.As promising alterna-tives for natural enzymes,nanozymes have broadened the way toward clinical medicine,food safety,environmental monitoring,and chemical production.The past decade has witnessed the rapid development of metal-and metal oxide-based nanozymes owing to their remarkable physicochemical proper-ties in parallel with low cost,high stability,and easy storage.It is widely known that the deep study of catalytic activities and mechanism sheds sig-nificant influence on the applications of nanozymes.This review digs into the characteristics and intrinsic properties of metal-and metal oxide-based nanozymes,especially emphasizing their catalytic mechanism and recent applications in biological analysis,relieving inflammation,antibacterial,and cancer therapy.We also conclude the present challenges and provide insights into the future research of nanozymes constituted of metal and metal oxide nanomaterials.

Carrier-free nanodrugs with efficient drug delivery and release for cancer therapy:From intrinsic physicochemical properties to external modification

The considerable development of carrier-free nanodrugs has been achieved due to their high drug-loading capability,simple preparation method,and offering“all-in-one”functional platform features.However,the native defects of carrier-free nanodrugs limit their delivery and release behavior throughout the in vivo journey,which significantly compromise the therapeutic efficacy and hinder their further development in cancer treatment.In this review,we summarized and discussed the recent strategies to enhance drug delivery and release of carrier-free nanodrugs for improved cancer therapy,including optimizing the intrinsic physicochemical properties and external modification.Finally,the corresponding challenges that carrier-free nanodrugs faced are discussed and the future perspectives for its application are presented.We hope this review will provide constructive information for the rational design of more effective carrier-free nanodrugs to advance therapeutic treatment.

Structure and intrinsic magnetic properties of MM_2Fe_(14)B(MM=La,Ce,Pr,Nd)alloys

MM_（33）Fe_（66）B（MM=La, Ce, Pr, Nd） alloys（mass ratio） were prepared by induction melting and heat-treated at 1353 K for 24 h to produce homogeneous MM_2Fe_（14） B phase. The phase structure and element distribution of the alloys were analyzed by X-ray diffraction（XRD） and scanning electron microscope（SEM）. The alloys were applied ball milling to obtain powders with good size distribution and then magnetic aligned in a static magnetic field of 2 T for 4 h, in order to achieve the intrinsic magnetic properties by vibrating sample magnetometer（VSM）. XRD results showed that the alloys were composed of the single 2：14：1 main phase and RE-rich phase, which was similar to Nd_2Fe_（14）B structure. Magnetic measurements showed that the saturation magnetization（Ms） and anisotropy field（HA） of the MM_（33）Fe_（66）B alloy were 11.3 k Gs and 48.4 k Oe, respectively, demonstrating its good potential as permanent magnets. The Curie temperature of the MM_（33）Fe_（66）B alloy was determined as 502.9 K by magnetization-temperature curves. Microstructure observation showed that Nd and Pr were mainly in the 2：14：1 ferromagnetic phase, while La and Ce prefered to aggregate in the RE-rich grain boundary phase, which is beneficial to fabricating（Pr, Nd, MM）_2Fe_（14）B magnets with good magnetic properties.

Structure and intrinsic magnetic properties of Sm_(1-x)Pr_xCo_5(x=0–0.6) compounds

In this work, the effects of Pr content on the structure and intrinsic magnetic properties of Sml-xPrxCO5 （x = 0-0.6） compounds prepared by induction melting were systematically investigated by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, and magnetic measurements. Microstructural observation and chemical composition analysis show that Sml xPrxCos compounds are composed of （Sin, Pr）Co （1：5） phase and （Sm, Pr）-rich grain boundary phase. XRD results show that all the Sml-xPrxCO5 compounds have a （Sm, Pr）lCo main phase with the hexagonal CaCus-type crystal structure and the （Sm, Pr）2 Co7 impurity phase. In addition, the detailed research shows that the lattice constants （a, c） and unit volume （V） are all enlarged with the increases in Pr con- tent. According to the magnetic measurements, as the Pr content increases to larger than 0.4, both the Curie tem- perature （Tc） and the anisotropy field （HA） of all the Pr- doped compounds decrease rapidly. Meanwhile, the mag- netization of Sml_xPr.Co5 compounds at applied field of 14 T （MI4 T） are observably improved with Pr doping content of x 〉 0.3. Among them, Smo.6Pro.4Co5 compound exhibits slightly lower HA and Tc, but much higher M14 T than those of the binary SmCos, indicating that doping of proper Pr content into SmCo5 compound can optimize the intrinsic magnetic properties. As a result, the optimal intrinsic magnetic properties of HA = 29.11 T,Tc = 989 K, and M14 T = 102.31 mA.m2.g-1 are obtained in Smo.6Pro.4C05 compound.

Intrinsic dielectric properties and vibration characteristics of La(Mg_(1/2)Sn_(1/2))O_(3) ceramic

La(Mg_(1/2)Sn_(1/2))O_(3)(LMS)ceramic was synthesized via the conventional solid-state reaction method.The main phase of the sample is LMS with a double perovskite structure(monoclinic P121/n1 symmetry),which is confirmed by X-ray diffraction.Scanning electron microscopy shows the sample is wellcrystallized with dense and uniform grains as well as clear grain boundaries.The Raman scattering and Fourier transform far-infrared reflection spectroscopies were employed to analyze the lattice vibrational modes of the sample.The Raman active modes were fitted by the Lorentz function,and the lattice vibrational modes were assigned and illustrated accurately.The four-parameter semiquantum model was applied to simulate the intrinsic dielectric properties,which agree well with the data calculated from the microscopic polarizability&damping angles.The A1g(La)Raman mode in A-site has a great impact on the dielectric loss,and F^(2)_(3u)mode makes the largest contribution to the dielectric constant and the dielectric loss.

Crystal structures and microwave dielectric properties of Sr_(2)MgWO_(6) ceramics at different sintering temperatures

Sr_(2)MgWO_(6)(SMW)is a typical perovskite oxide compound,but there has been little research on the effects of processing on its dielectric properties.In this work,SMW ceramics were prepared by solid-state synthesis with sintering at 1450℃,1475℃,1500℃and 1525℃,respectively.XRD results confirmed that the samples possessed double perovskite structure(Fm-3m).The Raman and FTIR spectra were used to study the lattice vibrational modes.The FPSQ model was used to obtain the fitting curves of the FTIR spectra and derive the intrinsic properties of the material that were found to be in agreement with the measured data.The structure-property relationships were successfully established based on the Raman mode results.The optimal sintering temperature of SMW ceramics was identified as 1475℃due to the excellent performances characteristics(ε_(r)=16.97,Q×f=23,872 GHz,τ_(f)=-35.38 ppm/℃)obtained at this temperature.This study explored the relationships among the crystal structures,lattice vibrational characteristics and dielectric properties of SMW ceramics,so as to further understand their dielectric response mechanism and lay a solid theoretical foundation for the development of microwave ceramics.

Structure, magnetic properties, and thermal stability of Sm(1-x)Tm_xCo_5compounds

Structure, magnetic properties, and thermal stability of ternary Sm1-xTmxCo5 compounds were studied via X-ray diffraction（XRD）, thermal magnetic analysis（TMA）, and magnetic measurements. XRD results show that all the compounds have a main phase of hexagonal CaCu5-type crystal structure with small amount of impurity phases; increasing Tm content is associated with contraction of the hexagonal unit cell in the direction of the c axis and expansion of the a and b parameters. TMA results indicate that the Curie temperature（TC） of Sm1-xTmxCo5 compounds gets higher with the increase in Tm content.Magnetic measurements show that both the magnetic anisotropy field（HA） and the magnetization at an applied field of 7 T（M7 T） decrease with the increase of Tm content. However, the thermal stability of both the HAand M7 Tof all the Tm doped compounds is remarkably improved compared with that of the pure SmCo5 compound, leading to the result that both the M7 Tand HAof Sm0.8Tm0.2Co5 .2are higher than those of SmCo5 compound at 473 K, which indicates the good potential of Tm doped compound in the practical applications at elevated temperature.

Precise prediction of dielectric property for CaZrO_(3) ceramic

As for CaZrO_(3)(CZ)ceramic,the reported dielectric property values,especially dielectric constants,were much different from 23 to 32,which is reliable and credible?Without precise property data,CZ can’t be further developed and utilized accurately.Herein,CZ ceramic was fabricated by a traditional two-step sintering process,then simulated and calculated the dielectric properties precisely at a microscopic polarization angle using the lattice vibrational spectra and the Clausius-Mossotti(C-M)as well as damping equations.The Raman and Fourier transform far-infrared modes were analyzed and used to predict the intrinsic properties,which were consistent well with the values calculated from C-M and damping equations.The intrinsic permittivity,after precise prediction,is about 20,which is reliable and credible.As for the dielectric loss,the value of about 6
×10^(-4)was obtained after precise calculation,which is similar to other results.

On-diagonal Heat Kernel Estimates for Schrödinger Semigroups and Their Application

We establish explicit and sharp on-diagonal heat kernel estimates for Schrödinger semigroups with unbounded potentials corresponding to a large class of symmetric jump processes.The approach is based on recent developments on the two-sided(Dirichlet)heat kernel estimates and intrinsic contractivity properties for symmetric jump processes.As a consequence,we present a more direct argument to yield asymptotic behaviors for eigenvalues of associated nonlocal operators.

STRUCTURE AND MAGNETISM OF RTiFe_(11) COMPOUNDS (R=Nd,Sm,Gd,Tb,Dy,Ho,Er and Y)

The crystallographic structure and intrinsic magnetic properties have been investigated in the RTiFe_(11) compounds, where Rrepresents Nd, Sin, Gd, Tb, Dy, Ho, Er and Y. The magnetic structure and the exchange interaction between various magnetic ions in RT Fe_(11) have been analysed. It is found that the intensity of R-Fe exchange interaction is proportional to((?)—1)~2J(J—1) for the heavy-rare-earth ions. while for the light rare earth, the effect caused by 5d-4f electron exchange interaction varying with rare-earth atoms must be taken into account. In RTiFe_(11) compounds the interatomic distance dependence on the exchange interaction between Fe-Fe atoms has been observed, and the result of enhancing the Curie temperature has been obtained. The Fe atomic magnetic moment in RTiFe_(11) is discussed in terms of the band theory, and the approach has been investigated on enhancement of saturation magnetization by means of substitution of atoms. RTiFe_(11) compoumds reveal a variety of magnetocrystalline anisotropy behaviors. For Fe sublattice the easy magnetization direction and the variation of the anisotropy constants with temperature have been measured with X-ray and magnetic techniques. On the basis of the crystalline field theory, by using a single-ion model, the anisotropy conatants and their temperature dependence of the R ions have been calculated, which helps explain the spin reorientations observed in RTiFe_(11).