Facile synthesis of Cu-doped manganese oxide octahedral molecular sieve for the efficient degradation of sulfamethoxazole via peroxymonosulfate activation

Advanced processes for peroxymonosulfate(PMS)-based oxidation are efficient in eliminating toxic and refractory organic pol-lutants from sewage.The activation of electron-withdrawing HSO_(5)^(-)releases reactive species,including sulfate radical(·SO_(4)^(-)),hydroxyl radical(·OH),superoxide radical(·O_(2)^(-)),and singlet oxygen(1O_(2)),which can induce the degradation of organic contaminants.In this work,we synthesized a variety of M-OMS-2 nanorods(M=Co,Ni,Cu,Fe)by doping Co^(2+),Ni^(2+),Cu^(2+),or Fe^(3+)into manganese oxide oc-tahedral molecular sieve(OMS-2)to efficiently remove sulfamethoxazole(SMX)via PMS activation.The catalytic performance of M-OMS-2 in SMX elimination via PMS activation was assessed.The nanorods obtained in decreasing order of SMX removal rate were Cu-OMS-2(96.40%),Co-OMS-2(88.00%),Ni-OMS-2(87.20%),Fe-OMS-2(35.00%),and OMS-2(33.50%).Then,the kinetics and struc-ture-activity relationship of the M-OMS-2 nanorods during the elimination of SMX were investigated.The feasible mechanism underly-ing SMX degradation by the Cu-OMS-2/PMS system was further investigated with a quenching experiment,high-resolution mass spec-troscopy,and electron paramagnetic resonance.Results showed that SMX degradation efficiency was enhanced in seawater and tap water,demonstrating the potential application of Cu-OMS-2/PMS system in sewage treatment.

Microwave irradiation-induced alterations in physicochemical properties and methane adsorption capability of coals:An experimental study using carbon molecular sieve

In order to comprehend the applicability of microwave irradiation for recovering coalbed methane,it is necessary to evaluate the microwave irradiation-induced alterations in coals with varying levels of metamorphism.In this work,the carbon molecular sieve combined with KMnO_(4)oxidation was selected to fabricate carbon molecular sieve with diverse oxidation degrees,which can serve as model substances toward coals.Afterwards,the microwave irradiation dependences of pores,functional groups,and highpressure methane adsorption characteristics of model substances were studied.The results indicated that microwave irradiation causes rearrangement of oxygen-containing functional groups,which could block the micropores with a size of 0.40-0.60 nm in carbon molecular sieve;meanwhile,naphthalene and phenanthrene generated by macro-molecular structure pyrolysis due to microwave irradiation could block the micropores with a size of 0.70-0.90 nm.These alterations in micropore structure weaken the saturated methane adsorption capacity of oxidized carbon molecular sieve by 2.91%-23.28%,suggesting that microwave irradiation could promote methane desorption.Moreover,the increased mesopores found for oxidized carbon molecular sieve after microwave irradiation could benefit CH4 diffusion.In summary,the oxidized carbon molecular sieve can act as model substances toward coals with different ranks.Additionally,microwave irradiation is a promising technology to enhance coalbed methane recovery.

In Situ Growth of 2D Metal–Organic Framework Ion Sieve Interphase for Reversible Zinc Anodes

Zinc metal anodes are gaining popularity in aqueous electrochemical energy storage systems for their high safety,cost-effectiveness,and high capacity.However,the service life of zinc metal anodes is severely constrained by critical challenges,including dendrites,water-induced hydrogen evolution,and passivation.In this study,a protective two-dimensional metal–organic framework interphase is in situ constructed on the zinc anode surface with a novel gel vapor deposition method.The ultrathin interphase layer(~1μm)is made of layer-stacking 2D nanosheets with angstrom-level pores of around 2.1Å,which serves as an ion sieve to reject large solvent–ion pairs while homogenizes the transport of partially desolvated zinc ions,contributing to a uniform and highly reversible zinc deposition.With the shielding of the interphase layer,an ultra-stable zinc plating/stripping is achieved in symmetric cells with cycling over 1000 h at 0.5 mA cm−2 and~700 h at 1 mA cm^(−2),far exceeding that of the bare zinc anodes(250 and 70 h).Furthermore,as a proof-of-concept demonstration,the full cell paired with MnO_(2) cathode demonstrates improved rate performances and stable cycling(1200 cycles at 1 A g−1).This work provides fresh insights into interphase design to promote the performance of zinc metal anodes.

High adsorption selectivity of activated carbon and carbon molecular sieve boosting CO_(2)/N_(2) and CH_(4)/N_(2) separation

Flue gas and coal bed methane are two important sources of greenhouse gases.Pressure swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is crucial.In this regard,in order to assess the better adsorbent for separating CO_(2) from flue gas and CH_(4) from coal bed methane,adsorption isotherms of CO_(2),CH_(4) and N_(2) on activated carbon and carbon molecular sieve are measured at 303.15,318.15 and 333.15 K,and up to 250 kPa.The experimental data fit better with Langmuir 2 compared to Langmuir 3 and Langmuir-Freundlich models,and Clausius-Clapeyron equation was used to calculate the isosteric heat.Both the order of the adsorbed amount and the adsorption heat on the two adsorbents are CO_(2)>CH_(4)>N_(2).The adsorption kinetics are calculated by the pseudo-first kinetic model,and the order of adsorption rates on activated carbon is N_(2)-CH_(4)>CO_(2),while on carbon molecular sieve,it is CO_(2)-N_(2)>CH_(4).It is shown that relative molecular mass and adsorption heat are the primary effect on kinetics for activated carbon,while kinetic diameter is the main resistance factor for carbon molecular sieve.Moreover,the adsorption selectivity of CH_(4)/N_(2) and CO_(2)/N_(2) were estimated with the ideal adsorption solution theory,and carbon molecular sieve performed best at 318.15 K for both CO_(2) and CH_(4) separation.The study suggested that activated carbon is a better choice for separating flue gas and carbon molecular sieve can be a strong candidate for separating coal bed methane.

一种Sieve极大似然估计的渐近性质

该文针对部分线性模型，在响应变量的观测值为Ⅰ型区间删失数据的情形下，讨论Ｓｉｅｖｅ极大似然估计的渐近性质．用三角级数来构造Ｓｉｅｖｅ空间，在一定条件下证明了该估计具有强相合性；得到了该估计的弱收敛速度，并且非参数部分的估计达到了最优收敛速度；还算出了参数部分的信息界．

Ultrastructural Studies on the Sieve Elements in Root Protophleom of Arabidopsis thaliana

The ultrastructures of the root protophleom sieve element at different developmental stages of Arabidopsis thaliana L. were investigated using the technique of high pressure freezing and freeze substitution fixing specimen. The results show that in the development of the sieve elements, the nuclei undergo typical characteristics of the programmed cell death (PCD): the nuclear envelopes form emboli, the chromatin condenses and aggregates towards the nuclear envelope, which degrades and fully disappears later. Before the nucleus degradation, neither the nuclear envelope undulation, nucleus lobe nor marked dilation (or bleb) of perinuclear space could be observed. In the cytoplasm of the mature sieve element, there are starch-like granules separately sheathed with a layer of membrane and usually with mitochondria around. These gnanules seem to provide substrates to mitochondria in their function. Small vacuoles originate from endoplasmic reticulum (ER), and no bigger vacuole was found.

Cytological Studies on the Development of Sieve Element and Floral Nectary Tissue in Arabidopsis thaliana

Ultrastructural changes in the sieve element and dense cells of nectariferous tissue during the development of floral nectary in Arabidopsis thaliana L. were investigated with transmission electron microscopy. Samples were prepared with high pressure freezing and freeze substitution techniques. The ultrastructure of dense cell was similar to that of sieve element at its early developmental stage. With the concurrent agglutination of chromatin in the nucleus, the abnormal location of organelles and the high density of cytoplasm, the ultrastructural characteristics in die dense cells of the nectariferous tissue and in the sieve element are matched with those of the programmed cell death in animal and plant reported in recent years. The disorganization of nucleus and most organelles in the differentiation of sieve elements and dense cells is closely associated with the transportation and modification of pre-nectar and the transference of nectar. This suggests that the cytological changes in sieve element and nectariferous tissue are closely associated with the nectary functional activities.

MODELING AND NUMERICAL SIMULATION OF ONBOARD MOLECULAR SIEVE OXYGEN GENERATION SYSTEM

A mathematical model for simulating concentric-bed and other components of molecular sieve oxygen concentrator is established. In the model, the binary Langmuir equilibrium adsorption equation is adopted to describe the adsorption performance of the adsorbent, the linear driving force (LDF) model is used to describe the mass transfer rate, and the thermal effect during adsorption is considered. The finite difference method is used in simulation and comparison. Numerical results have a reasonable agreement with the experimental research.

STUDY ON THE THREE PHASE EQUILIBRIA OF ETHANOL WATER 4A MOLECULAR SIEVE

Vapor liquid solid three phase equilibria of ethanol water 4A molecular sieve system are studied experimentally and theoritically. It is proved that the addition of adsorbent does not change the equilibrium relation between vapor and bulk liquid phase. A calculation procedure is proposed to predict vapor liquid solid (adsorbent) three phase euquilibria.

The synthesis of Co-doped SAPO-5 molecular sieve and its performance in the oxidation of cyclohexane with molecular oxygen

Silicoaluminophosphate（SAPO） molecular sieves doped with cobalt（Co-SAPO-5） were synthesized hydrothermally with different concentrations of Co.Each sample was characterized by X-ray diffraction,N2 adsorption-desorption,scanning electron microscopy,ultraviolet-visible spectroscopy,temperature-programmed desorption of NH3（NH3-TPD）,and infrared spectrascopy of adsorbed pyridine（Py-IR）.The results showed that Co was highly dispersed in the Co-SAPO-5 samples.In addition,a part of the Co content had been incorporated into the SAPO-5 framework,while the remainder existed on the surface as extra-framework Co.The surface areas of the Co-SAOP-5 samples were similar to the SAPO-5 sample.However,the pore volumes of the Co-SAOP-5 samples were lower than that of the SAOP-5 sample.As the concentration of Co increased,the pore volume gradually decreased because extra-framework cobalt oxide was present on the catalyst surface.NH3-TPD and Py-IR results revealed that the amount of Br（？）nsted acid and the total amount of acid for the Co-SAPO-5 samples were higher than that for the SAPO-5 sample.These values were also higher for samples with higher Co content.The catalytic activity of the Co-SAPO-5 samples was evaluated for the oxidation of cyclohexane with molecular oxygen.When Co was added to the SAPO-5 catalyst,the catalytic activity of the Co-SAPO-5 catalysts improved.In addition,the conversion of cyclohexane increased as the Co content in the Co-SAPO-5 catalysts increased.However,with a high conversion of cyclohexane（6.30%）,the total selectivity of cyclohexanone（K） and cyclohexanol（A） decreased sharply.The K/A ratio ranged from 1.15 to 2.47.The effects of reaction conditions（i.e.,reaction temperature,reaction time,initial oxygen pressure,and the catalyst amount） on the performance of the Co-SAPO-5 catalysts have also been measured.Furthermore,the stability of the Co-SAPO-5 catalyst was explored and found to be good for the selective oxidation of cyclohexane by molecular oxygen.

A n-fold Calculating Sieve Formula for Some Symmetric Sets

This paper introduces a method of sieve which can be to calculate the number of residues of the integers 1,2,...,2a sifted by n paiwise coprime numbers.

基于Sieve Bootstrap方法的长记忆过程均值变点的检验

本文提出一个新的统计量来检测长记忆时间序列中可能存在的均值变点,在原假设下推导出了检验统计量的极限分布在备择假设下证明了检验方法的一致性.为便于实际应用还提出了一种Sieve Bootstrap方法来近似统计量的临界值.模拟结果表明本文方法不仅可以很好的控制经验水平,而且相比已有均值变点检验的方法经验势也有了一定幅度的提高.

用Sieve实现邮件过滤

Sieve是一种用来产生电子邮件过滤器的语言。为便于广大用户的使用 ,它设计得相当简单 ,但同时又内涵丰富 ,应用广泛。介绍了一种应用Sieve语言的电子邮件过滤系统。

CH4/N2 separation on methane molecules grade diameter channel molecular sieves with a CHA-type structure

Samples of methane molecules grade diameter channel CHA-type molecular sieves(Chabazite-K, SAPO-34 and SSZ-13) were investigated using the adsorption separation of CH4/N2 mixtures. The isotherms recorded for CH4 and N2 follow a typical type-Ι behavior, which were fitted well with the Sips model(R2>0.999) and the selectivity was calculated using IAST theory. The results reveal that Chabazite-K has the highest selectivity(SCH4/N= 5.5).2 SSZ-13 has the largest capacity, which can adsorb up to a maximum of 30.957 cm3·g-1(STP) of CH4, due to it having the largest pore volume and surface area, but the lowest selectivity(SCH4/N2= 2.5). From the breakthrough test, we can conclude that SSZ-13 may be a suitable candidate for the recovery of CH4 from low concentration methane(CH4<20%) based on its larger pore volume and higher CH4 capacity. Chabazite-K is more suited to the separation of high concentration methane(CH4>50%) due to its higher selectivity.

Kinetics and Mechanism of the Photo-oxidation of Thiophene by O_2 Adsorbed on Molecular Sieves

Photochemical oxidation of thiophene in n-octane/water extraction system using O2 as oxidant was studied. The reaction mechanism ofthiophene oxidation was proposed. Results obtained here can be used as the reference for the oxidative desulfurization of gasoline because thiophene is one of the main components containing sulfur in fluid catalytic cracking gasoline. Thiophene dissolved in n-octane was photodecomposed and removed into the water phase at ambient temperature and atmospheric pressure. A 500 W high-pressure mercury lamp （main wave length 365 nm, 0.22 kW/m） was used as light source for irradiation, and air was introduced by a gas pump to supply O2. Thiophene can be photo-oxidized to sulfone, oxalic acid, SO4^2-, and CO2. The desulfurization yield of thiophene in n-octane is 58.9% under photo-irradiation for 5 h under the conditions of air flow at 150 mL/min and V（water）：V（n-octane）=1：1. It can be improved to 92.3% by adding 0.15 g zeoliteartificial into 100 mL reaction system, which is the adsorbent for O2 and thiophene. And under such conditions, the photo-oxidation kinetics of thiophene with O2/zeoliteartificial is first-order with an apparent rate constant of 0.5047 h^-1 and a half-time of 1.37 h. The sulfur content can be depressed from 800 μL/L to less than 62 μL/L.

Malus sieversii: the origin, flavonoid synthesis mechanism, and breeding of red-skinned and red-fleshed apples

Flavonoids play essential roles in human health.Apple(Malus domestica Borkh.),one of the most widely produced and economically important fruit crops in temperate regions,is a significant source of flavonoids in the human diet and is among the top nutritionally rated and most widely consumed fruits worldwide.Epidemiological studies have shown that the consumption of apples,which are rich in a variety of free and easily absorbable flavonoids,is associated with a decreased risk of various diseases.However,apple production is challenged by serious inbreeding problems.The narrowing of the hereditary base has resulted in apples with poor nutritional quality and low flavonoid contents.Recently,there have been advances in our understanding of the roles that Malus sieversii(Ledeb.)M.Roem has played in the process of apple domestication and breeding.In this study,we review the origin of cultivated apples and red-fleshed apples,and discuss the genetic diversity and construction of the core collections of M.sieversii.We also discuss current research progress and breeding programs on red-skinned and red-fleshed apples and summarize the exploitation and utilization of M.sieversii in the breeding of high-flavonoid,and red-fleshed apples.This study highlights a valuable pattern of horticultural crop breeding using wild germplasm resources.The future challenges and directions of research on the molecular mechanisms of flavonoid accumulation and high-flavonoid apple breeding are discussed.

Beyond graphene oxides: Emerging 2D molecular sieve membranes for efficient separation☆

Recent decades witnessed the significant progress made in the research field of 2D molecular sieve membranes.In comparison with their 3D counterparts, 2D molecular sieve membranes possessed several unique advantages like significantly reduced membrane thickness(one atom thick in theory) and diversified molecular sieving mechanisms(in-plane pores within nanosheets & interlayer galleries between nanosheets). M. Tsapatsis first carried out pioneering work on fabrication of lamellar ZSM-5 membrane. Since then, diverse 2D materials typically including graphene oxides(GOs) have been fabricated into membranes showing promising prospects in energy-efficient gas separation, pervaporation, desalination and nanofiltration. In addition to GOs, other emerging 2D materials, including 2D zeolites, 2D metal–organic frameworks(MOFs), 2 D covalent-organic frameworks(COFs), layered double hydroxides(LDHs), transition metal dichalcogenides(TMDCs), MXenes(typically Ti3C2TX), graphitic carbon nitrides(typically g-C3N4), hexagonal boron nitride(h-BN) and montmorillonites(MT) are showing intriguing performance in membrane-based separation process. This article summarized the most recent developments in the field of 2D molecular sieve membranes aside from GOs with particular emphasis on their structure–performance relationship and application prospects in industrial separation.

Selective synthesis of triacetin from glycerol catalyzed by HZSM-5/MCM-41 micro/mesoporous molecular sieve

HZSM-5/MCM-41 molecular sieve (H-ZM) catalysts with well-defined micro/mesoporous structures were synthesized and showed high performance for selective synthesis of triacetin via the esterification reaction of glycerol with acetic acid. The conversion of glycerol was demonstrated to be 100% and the triacetin selectivity was over 91%, which can be attributed to the synergistic effect regarding suitable acidic property, excellent diffusion efficiency and good stability derived from the combined advantages of microporous molecular sieve HZSM-5 and mesoporous molecular sieve MCM-41.

Catalytic Transformation of Bio-oil to Olefins with Molecular Sieve Catalysts

Catalytic conversion of bio-oil into light olefins was performed by a series of molecular sieve catalysts, including HZSM-5, MCM-41, SAPO-34 and Y-zeolite. Based on the light olefins yield and its carbon selectivity, the production of light olefins decreased in the following order： HZSM-5〉SAPO-34〉MCM-41〉Y-zeolite. The highest olefins yield from bio-oil using HZSM- 5 catalyst reached 0.22 kg/kgbio-oil with carbon selectivity of 50.7% and a nearly complete bio-oil conversion. The reaction conditions and catalyst characterization were investigated in detail to reveal the relationship between the catalyst structure and the production of olefins. The comparison between the pyrolysis and catalytic pyrolysis of bio-oil was also performed.

Investigation of ZSM-5/MCM-41 Composite Molecular Sieve for Reducing Olefin Content of FCC Gasoline

ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve were characterized by X-ray powder diffractometry,N_2 adsorption isotherms,temperature programmed desorption of ammonia and scanning electron microscopy and their properties were analyzed.Using FCC gasoline as the feed,activities of different molecular sieves for reducing olefin content were investigated in a continuous high-pressure micro-reactor unit under the following conditions:a reaction temperature of 400℃,a reaction time of 2 h,a weight hourly space velocity of 3h^(-1),and a reaction pressure of 2.0 MPa.The results showed that the HMCM-41 molecular sieve had low reaction performance,and the HZSM-5 molecular sieve demonstrated high aromatization activity,while the ZSM-5/MCM- 41 composite molecular sieve exhibited a best olefin-reducing performance because of its high isomerization activity and moderate aromatization activity.With a largest olefin-reducmg capability and a reasonable distribution of products,the composite molecular sieve was more suitable for FCC gasoline upgrading compared to other three catalysts.