Low-cost synthesis of nanoaggregate SAPO-34 and its application in the catalytic alcoholysis of furfuryl alcohol

Silicoaluminophosphate-34(SAPO-34) molecular sieves have important applications in the petrochemical industry as a result of their shape selectivity and suitable acidity. In this work, nanoaggregate SAPO-34 with a large external surface area was obtained by dissolving pseudoboehmite and tetraethylorthosilicate in an aqueous solution of tetraethylammonium hydroxide and subsequently adding phosphoric acid. After hydrolysis in an alkaline solution, the aluminum and silicon precursors exist as Al(OH)4-and SiO2(OH)-, respectively;this is beneficial for rapid nucleation and the formation of nanoaggregates in the following crystallization process. Additionally, to study the effect of the external surface area and pore size on the catalytic performance of different SAPO-34 structures, the alcoholysis of furfuryl alcohol to ethyl levulinate(EL) was chosen as a model reaction. In a comparison with the traditional cube-like SAPO-34, nanoaggregate SAPO-34 generated a higher yield of 74.1% of EL, whereas that with cube-like SAPO-34 was only 19.9%. Moreover, the stability was remarkably enhanced for nanoaggregate SAPO-34. The greater external surface area and larger number of external surface acid sites are helpful in improving the catalytic performance and avoiding coke deposition.

DTL facilitates the Fanconi anemia pathway for ultraviolet-induced DNA repair in retinal pigment epithelial cells

The excessive energy of light,especially the invisible rays with lower wavelength,is basically absorbed by retinal pigment epithelium(RPE)and usually causes DNA damage.The molecular mechanism behind DNA damage repair response to this frequent stress in RPE is not clearly understood.In this study,we determined that the Fanconi anemia(FA)pathway was activated in human RPE ARPE-19 cells after ultraviolet(UV)B and C treatment.Moreover,immunoprecipitation(IP)of FANCD2 indicated that denticleless E3 ubiquitin protein ligase homolog(DTL)closely interacted with FANCD2.Knockdown of DTL weakened the activity of the FA pathway in ARPE-19 cells responding to UV treatment.Finally,the DTL promoter was incubated with a biotin-labeled probe and pulled down by streptavidin beads followed by the genomic DNA sonication.p53 was indicated by mass spectrum and further determined by chromatin IP assay.Taken together,our results demonstrated that DTL regulated by p53 could activate the FA pathway for UV-induced DNA damage repair in retinal pigment epithelial cells.

Tumor microenvironment of cancer stem cells:Perspectives on cancer stem cell targeting

There are few tumor cell subpopulations with stem cell characteristics in tumor tis-sue,defined as cancer stem cells(CSCs)or cancer stem-like cells(CSLCs),which can recon-struct neoplasms with malignant biological behaviors such as invasiveness via self-renewal and unlimited generation.The microenvironment that CsCs depend on consists of various cellular components and corresponding medium components.Among these factors existing at a variety of levels and forms,cytokine networks and numerous signal pathways play an important role in signaling transduction.These factors promote or maintain cancer cell stem-ness,and participate in cancer recurrence,metastasis,and resistance.This review aims to summarize the recent molecular data concerning the multilayered relationship between CsCs and CsC-favorable microenvironments.We also discuss the therapeutic implications of target-ing this synergistic interplay,hoping to give an insight into targeting cancer cell stemness for tumortherapyandprognosis.

Phosphorus-enriched biochar from biogas residue of Eichhornia crassipes:transformation and release of phosphorus

Pyrolysis is an effective technology for treating and utilizing biogas residue.To explore the phosphorus(P)supply capacity of the biochar generated from biogas residue of Eichhornia Crassipes,the P speciation of E.crassipes biogas residue and biomass during pyrolysis(300-700°C)was analyzed by combining sequential chemical extraction,31P nuclear magnetic resonance(NMR)and P K-edge X-ray absorption near edge structure(XANES)spectroscopy.Pyrolysis treatment promoted the conversion of amorphous Ca-P phases in biogas residue and biomass into crystalline hydroxyapatite(HAP)phase,which matched the formation of stable HCl-P pools in the biochar derived from biogas residue(AEBs,22.65-82.04%)and biomass(EBs,13.08-33.52%)in the process of pyrolysis.Moreover,the total P contents in AEBs(19.43-28.92 mg g^(−1))were higher than that of EBs(3.41-5.26 mg g^(−1)),indicating that AEBs had a great P reclamation potential.The P release kinetics from AEBs and EBs in water were evaluated via an incubation experiment for 360 h.The P release from both AEBs and EBs conformed to the pseudo-second order kinetics model(R^(2)>0.93),but their P release behaviors were different.The P release of AEBs conformed to the diffusion-re-adsorption model,while that of EBs accorded with the diffusion-dissolution model.The diffusive gradients in thin-films(DGT)analysis showed that AEBs could significantly increase soil available P content as compared with EBs.Hence,the biochar produced from biogas residue of E.crassipes via pyrolysis has a good application potential as a P fertilizer.

Release behavior of soluble salts in MSWI bottom ash used as road basement materials under continuous rainfall conditions

The bottom ash is increasingly used as a substitute aggregate material in road construction in China,and road salting is the major salt source in groundwater.Continuous rainfall releases soluble salts from the bottom ash subgrade into the surrounding soil and groundwater,resulting in potential hazards.Different methods were employed to simulate and collect runoff water during rainfall events,including batch leaching test,dynamic leaching test and constant head test,to assess environmental impact of bottom ash as road basement materials under continuous rainfall conditions.This study simulated the seepage of bottom ash backfill roads under different rainfall intensities,rainfall times,and rainfall pH values.A comprehensive sampling and laboratory testing program was undertaken to characterize the environmental impact of soluble salts from bottom ash.The obtained results reveal that the leaching concentrations of Cl^(−)and SO_(4)^(2−)exceed the limit specified in the class V standard of surface water,which are 2.06–2.17 times and 1.08–1.25 times,respectively.By examining the long-term environmental influence under the condition of continuous rainfall,the leaching of Cl^(−)mainly occurs in the early leaching stage,and the maximum leaching concentration reaches 19,700 mg/L.The release concentration of Cl^(−)begins to be lower than the class V standard of surface water when continuous rainfall approaches the total rainfall for 13 months.The cumulative release of Cl^(−)in the bottom ash is 2.8–5.4 mg/g.Both rainfall intensity and rain pH affect the release of Cl^(−).The obtained results derived from the constant head tests indicate that stagnant water caused by rainfall deteriorates the release of soluble salt into the groundwater in only 1 day,especially at the early stage of 12 h.This work provides some basic information about how to minimize damage to the surrounding environment caused by the leaching of salt in bottom ash.

含水率及温度对中药渣热解特性影响

中药渣类高含水工业生物质废弃物能源化清洁处理技术开发尤为重要。本工作以中药渣为研究对象,结合热重表征手段,利用固定床对其进行热解特性研究。研究不同原料含水率、热解温度及热解速率下的热解产物产率分布及其成分和特性,及氮元素在气、液、固三相产物中分布规律。结果表明,该中药渣完全热解的温度范围为650~850℃。在此温度范围中升高温度有利于热解过程,提升了热解效率及可燃气品质,可燃气、半焦中的氮元素含量下降,热解油中的含量上升。降低含水率能够提高热解效率,热解油中含氮化合物含量增加,促使氮元素向液相迁移。中药渣烘干的过程中减少了碱金属含量,影响热解油组分。提高热解速率也能一定程度上影响热解产物组分及氮元素分布。本研究可为中药渣热解过程优化及含氮化合物排放控制提供理论基础。

疏水性氨基酸的羟基化研究进展

羟基化氨基酸在生物技术和分子生物学中具有独特价值,具有抗真菌、抗菌、抗病毒和抗癌的特性。通过比较化学合成与生物催化合成羟基氨基酸的异同,选择具有高对映结构选择性的生物催化合成方法成为羟基氨基酸合成的首选。生物催化实现疏水性氨基酸的羟基化和羟化酶紧密相关,而羟化酶又是单核非血红素Fe(Ⅱ)和α-酮戊二酸依赖型双加氧酶(Fe/αKGDs)的一种,Fe/αKGDs存在共性催化机制。因此,疏水性氨基酸在被催化的过程中,会利用关键中间体高价铁-超氧复合体(Fe(Ⅳ)=O)引起多种氧化转化,从而完成羟基化过程。文中就疏水性氨基酸的羟基化合成及功能应用,尤其是(2S,3R,4S)-4-羟基-异亮氨酸(4-HIL)和羟脯氨酸,进行了详细的阐述,探讨了Fe/αKGDs的共性催化反应机制,并对羟基氨基酸在基础研究和工业中的应用进行了综述。

植物响应联合胁迫机制的研究进展

自然界中,植物通常面对多重联合胁迫。在全球气候变化日益加剧的背景下,多重联合胁迫对植物生长发育及作物产量形成的不利影响日益显著。阐明植物响应和适应联合胁迫的生理与分子机制,对人们理解植物对自然环境的适应机理,及培育耐受联合胁迫的新品种有重要意义。研究表明,植物响应联合胁迫的机制是特异的,不能简单地从单一胁迫响应叠加来推断。植物遭受联合胁迫时,各种生理、代谢和信号途径相互作用,使得植物响应联合胁迫非常复杂。该文综述了植物响应联合胁迫的生理与分子机理的最新进展,并阐述了植物响应联合胁迫的研究方法。

Crystal-to-crystal transformation from the triclinic to the cubic crystal system by partial desolvation

Diffusion reaction of the labile building block Mg（acacCN）2 （acacCN= 3-cyanoacetylacetonate） with silver salts leads to a series of solvated Mg/Ag bimetallic coordination polymers with composition [Mg（acacCN）aAg].solvent. Despite their common stoichiometry, the topology of these polymers depends on the solvent of crystallization. The two-dimensional coordination compound [Mg（acacCN）aAg]-4CHCl3 in space group P]- is obtained as platelet-shaped crystals from a mixture of methanol and chloroform. When kept in the reaction mixture, these thin plates within one week convert to isometric tetrahedral crystals of the 3D network [Mg（acacCN）3Ag]. 2CHC13 in the cubic space group/9213. The transformation reaction proceeds via dissolution and recrystallization. The co-crystallized solvent molecules play an important role for stabilizing the target structure： They subtend Cl...Cl contacts and interact via non- classical C-H.-. O hydrogen bonds with the coordination framework. In the new cubic coordination network, both Mg（II） and Ag（I） adopt octahedral coordination, with unprecedented face-sharing by bridging O atoms of three acetylacetonato moieties. Prolonged standing of [Mg（acacCN）3Ag]-2CHCl3 in the reaction medium leads to further degradation, under formation of [Ag（acacCN）].

Ab initio calculation of the ground and first excited states of the lithium dimer

Based on a high level ab initio calculation which is earned out with the multireference configuration interaction method under the aug-cc-pVXZ(AVXZ)basis sets,X=T,Q,5,the accurate potential energy curves(PECs)of the ground state X^(1)Σ_(g)^(+)and the first excited state A^(1)Σ_(u)^(+)of Li_(2)are constructed.By fitting the ab initio potential energy points with the MurrellSorbie potential function,the analytic potential energy functions(APEFs)are obtained.The molecular bond length at the equilibnum(R_(e)),the potential well depth(D_(e)),and the spectroscopic constants(B_(e),ω_(e),α_(e),andω_(e)χ_(e))for the X^(1)Σ_(g)^(+)state and the A^(1)Σ_(u)^(+)state are deduced from the APEFs.The vibrational energy levels of the two electronic states are obtained by solving the time-independent Schrodmger equation with the Founer gnd Hamiltonian method.All the spectroscopic constants and the vibrational levels agree well with the experimental results.The Franck-Condon factors(FCFs)corresponding to the transitions from the vibrational level(v’=0)of the ground state to the vibrational levels(v"=0-74)of the first excited state have been calculated.The FCF for the vibronic transition of A^(1)Σ_(u)^(+)(v"=0)←X^(1)Σ_(g)^(+)(v’=0)is the strongest.These PECs and corresponding spectroscopic constants provide reliable theoretical references to both the spectroscopic and the molecular dynamic studies of the Li_(2)dimer.

Quantification and distribution of extractable metals of MSWI bottom ash in view of its valorization in China

Metal recovery from bottom ash was deemed to be significant to achieve a higher stability of bottom ash and recycle valuable extractable metals.In China,the existing rugged industrial production ignores the actual metal distribution and thus fails to exploit the utilization potential of recoverable metals in bottom ash.Based on these findings,this work was proposed to obtain a comprehensive and in-depth study on the recoverability of metals in bottom ash.First,the particle size distribution and elemental composition of the bottom ash were analyzed.Then,complete information on the recoverable metals in bottom ash fractions with different sizes was obtained by washing,sorting,crushing,density separation and XRF(X Ray Fluorescence)analysis.The results showed that the smaller than 5 mm fraction accounted for up to 60%of the bottom ash,and the 5–20 mm fractions accounted for about 15%.The material characterization revealed that the contents of recoverable Fe,stainless steel,Al and Cu in bottom ash were averagely 9.01%,0.136%,0.78%and 0.08%,respectively.About 50%of Fe,68%of Al,61%of Cu,and 22%of stainless steel were distributed in smaller than 10 mm fraction.Particularly,Fe was evenly distributed among 0–2 mm,2–5 mm,5–10 mm fractions,and the content was between 5.41%and 7.5%.Non-magnetic stainless steel was mainly distributed in 20–40 mm and larger than 40 mm fractions.The highest share of Al was present in the fractions between 5 mm and 20 mm,accounting for 48%of the total aluminum.About 45.6%of the Cu was enriched in the 5–10 mm fraction.However,the Zn content was less than 0.01%.This work provides an in-depth understanding and information on metal recovery as well as promisingly guide ash utilization.