EFFECT OF SOLVENT ON ZEOLITE SYNTHESIS

Introductionltistvellknox`nthath}'drothcrmalcn'stallizationisaconventionaltechniqueforzeoliteandmolccularsicvcs}nthcsls.Watcrassolvcntplaystheroleofminerali.ation[ll.Inl985,BibbyandDalcrcportedfirstl}'thes}'nthcsisofsilica-sodaliteinethyleneglycolsol.e.tl2l.Sincetllcn,man}'kindsofzeolitcst"ercpreparedinnon-aqueoussystemsHott'ever,noinformationonthcinfluenccofsolvcntonzcolitcsynthesishasbecnreported.Inthispapcr,t"crcportanintcrcstingcxamplc.Incascsofnosolventandusingx`atcr,cth}'lcneglycolandc…     

Mechanochemical generation of acid-degradable poly(enol ether)s

In an effort to develop polymers that can undergo extensive backbone degradation in response to mechanical stress, we report a polymer system that is hydrolytically stable but unmasks easily hydrolysable enol ether backbone linkages when force is applied. These polymers were synthesized by ring-opening metathesis polymerization (ROMP) of a novel mechanophore monomer consisting of cyclic ether fused bicyclohexene. Hydrogenation of the resulting polymers led to significantly enhanced thermal stability (T_d > 400 °C) and excellent resistance toward acidic or basic conditions. Solution ultrasonication of the polymers resulted in up to 65% activation of the mechanophore units and conversion to backbone enol ether linkages, which then allowed facile degradation of the polymers to generate small molecule or oligomeric species under mildly acidic conditions. We also achieved solid-state mechano-activation and polymer degradation via grinding the solid polymer. Force-induced hydrolytic polymer degradability can enable materials that are stable under force-free conditions but readily degrade under stress. Facile degradation of mechanically activated polymechanophores also facilitates the analysis of mechanochemical products.

A mechanically responsive polymer system that is hydrolytically stable without stress, but unmasks enol ether backbone linkages under force to allow facile hydrolytic degradation.     

Some Conditions on Real Hypersurfaces in Quaternionic Projective Spaces in Terms of Lie Derivatives

The purpose of this paper is to give a non-existence property with the Lie derivative of the structure tensors φ _i and some characterizations of real hypersurfaces of type A ₁, A ₂ in a quaternionic projective space QP ^m in terms of the Lie derivatives of the second fundamental tensor A and the induced Riemannian metric g on the distribution D ^⊥ = Span {U ₂, U ₂, U ₃}. This revised version was published online in June 2006 with corrections to the Cover Date.     

Self-limiting growth of ZnO films on (0 0 0 1) sapphire substrates by atomic layer deposition at low temperatures using diethyl-zinc and nitrous oxide

Atomic layer deposition (ALD) of zinc oxide (ZnO) films on (0 0 0 1) sapphire substrates was conducted at low temperatures by using diethyl-zinc (DEZn) and nitrous oxide (N₂O) as precursors. It was found that a monolayer-by-monolayer growth regime occurred at 300 °C in a range of DEZn flow rates from 5.7 to 8.7 μmol/min. Furthermore, the temperature self-limiting process window for the ALD-grown ZnO films was also observed ranging from 290 to 310 °C. A deposition mechanism is proposed to explain how saturated growth of ZnO is achieved by using DEZn and N₂O. Transmission spectroscopic studies of the ZnO films prepared in the self-limiting regime show that the transmittances of ZnO films are as high as 80% in visible and near infrared spectra. Experimental results indicate that ZnO films with high optical quality can be achieved by ALD at low temperatures using DEZn and N₂O precursors.     

Tunable Electronic Memory Performances Based on Poly(Triphenylamine) and Its Metal Complex via a SuFEx Click Reaction

A triphenylamine derivative decorated with an azobenzene group (TDA) was synthesized via a SuFEx click reaction and its polymer, poly(triphenylamine) (PTDA), was polymerized through a redox polymerization. More interestingly, its polymeric metal complex, PTDA‐Fe, can be simply obtained via one‐pot reaction between TDA and FeCl₃ owing to TDA showing a strong affinity to the Fe^III ion. The sandwich memory device based on PTDA nanofilms as active layers exhibited a binary memory performance. However, the memory device based on its polymeric metal complex exhibited a unique ternary memory behavior. The different memory performances should come from the different conductive mechanism. The mechanism of such ternary memory devices is illustrated based on both the theoretical calculation and experiments. Our work provides new insights into the preparation of novel materials for multilevel memory devices.     

Near‐Infrared Afterglow Semiconducting Nano‐Polycomplexes for the Multiplex Differentiation of Cancer Exosomes

The detection of exosomes is promising for the early diagnosis of cancer. However, the development of suitable optical sensors remains challenging. We have developed the first luminescent nanosensor for the multiplex differentiation of cancer exosomes that bypasses real‐time light excitation. The sensor is composed of a near‐infrared semiconducting polyelectrolyte (ASPN) that forms a complex with a quencher‐tagged aptamer. The afterglow signal of the nanocomplex (ASPNC), being initially quenched, is turned on in the presence of aptamer‐targeted exosomes. Because detection of the afterglow takes place after the excitation, background signals are minimized, leading to an improved limit of detection that is nearly two orders of magnitude lower than that of fluorescence detection in cell culture media. Also, ASPNC can be easily tailored to detect different exosomal proteins by changing the aptamer sequence. This enables an orthogonal analysis of multiple exosome samples, potentially permitting an accurate identification of the cellular origin of exosomes for cancer diagnosis.     

Palladium-catalyzed tandem cyclization of fluorinated imidoyl chlorides with 2-bromophenylboronic acid: Synthesis of 6-fluoroalkyl-phenanthridines

An efficient method has been developed to synthesize 6-fluoroalkyl-phenanthridines via the palladium-catalyzed tandem cyclization of fluorinated imidoyl chlorides with 2-bromophenylboronic acid. This methodology facilitates the rapid synthesis of 6-fluoroalkyl-phenanthridines through dual C–C bond formation in an oxidant-free one-pot manner.     

Preparation of a polyhedral oligomeric silsesquioxanes hybrid monolith via a single‐step ring‐opening polymerization for pressurized capillary electrochromatography

An organic‐silica hybrid monolith was prepared by a single‐step ring‐opening polymerization of octaglycidyldimethylsilyl polyhedral oligomeric silsesquioxane (POSS‐epoxy), polyethylenimine (PEI), and β‐cyclodextrin (β‐CD) in a ternary porogenic solvent consisting of polyethylene glycol, 1,4‐butanediol, and 1‐propanol. The framework of POSS‐PEI hybrid monolith could offer well‐defined 3D skeleton, while β‐CD with the ability of forming a host‐guest inclusion complexes with a variety of compounds could show an ability of specific selection. The obtained hybrid monoliths were successfully applied for separation of phenols, benzoic acids, and nucleobases. Especially due to the introduction of β‐CD, positional isomers including hydroquinone and resorcinol, o‐nitrophenol and p‐nitrophenol, as well as p‐chlorophenol and o‐chlorophenol were baseline separated and the column efficiency reached 82 300 plates/m for hydroquinone.     

Influence of combustion temperature and coal types on alumina crystal phase formation of high-alumina coal ash

The alumina content (more than 40%) of high-alumina coal ash is comparative to the middle content bauxite ores in China. So far, in order to meet the high demand of alumina and the rise of circular economy industrial chain, extracting alumina from coal ash has become a way to comprehensively utilize high-alumina coal ash. However, this process has high requirements on the crystal phase and stability of alumina. Different from most studies, this paper focuses on how to produce coal ash more beneficial to the later refining of aluminum. Therefore, the effects of combustion temperature and coal types by classifying high-alumina coal into dull coal and bright coal on alumina crystal phase formation were studied. Through proximate analysis, ultimate analysis, calorific value analysis, X-ray fluorescence spectroscopy, X-ray diffraction (XRD) and scanning electron microscope (SEM) and other methods, it is found that γ-Al₂O₃ in high-alumina coal ash translated into more stable θ-Al₂O₃ and finally α-Al₂O₃ when combustion temperature is higher than 1000°C. Thus compared with pulverized coal boilers, circulating fluidized bed (CFB) boilers with lower combustion temperature can produce higher quality coal ash. Moreover, at the same combustion temperature, alumina crystal phase in dull coal ash is relatively less stable than that in bright coal ash, which is more suitable to the later refining and electrolysis of aluminum.     

一种中高频激励下动力系统响应的级数展开改进算法

针对频率响应函数的级数展开法在中高频激励时计算发散的问题,提出一种新的级数展开改进算法.将系统的结构模态划分为低阶和截断的高阶模态,在模态叠加分析的基础上,将频率响应函数进行泰勒级数展开.根据高低阶模态对质量矩阵和刚度矩阵的耦合特性,用低阶模态及系统矩阵表达高阶模态对响应的影响.研究结果表明,该算法将频率响应函数的级数展开法扩展到高频激励和中频激励范围阶段,在非完备模态条件下提高了频率响应函数的计算精度,数值计算检验了该方法准确可靠并有很好的收敛性.