Bidirectional role of synthetic musk tonalide as photosensitizer and activator on amino acids:Formation of sensitizer imine at aqueous chemistry interface of skin

Personal care products(PCPs)inevitably come into contact with the skin in people’s daily life,potentially causing adverse effects on human health.The adverse effects can be exacerbated under UV irradiation but are rarely studied.In this study,to clearly understand the damage of representative PCPs to human skin and their photochemical transformation behaviors,fragrance tonalide(AHTN)was measured in the presence of amino acids as a basic building block of human tissue.The results showed that amino acids could decelerate the photochemical transformation rate of AHTN,increasing the likelihood of AHNT persisting on the skin surface and the health risk to the human being.Further,the interaction between amino acids and AHTN was investigated.AHTN could play bidirectional roles in damaging amino acids:the photosensitizer and reactive activator.As a photosensitizer,the ^(1)O_(2) generated from the AHTN photosensitization was partly employed to oxidative damage amino acids.Furthermore,by combining experiments with quantum chemical computation,the carbonyl group of the activator AHTN was found to be the active site to activate the N-containing group of amino acids.The activation mechanism was the electron transfer between AHTN and amino acids.Imines formed during the photochemical transformation of AHTN with histidine/glycine were the molecular initiating event for potential skin sensitization.This study reported for the first time that skin photosensitizer formation threatens human health during the photochemical transformation of AHTN.

Competing esterification and oligomerization reactions of typical long-chain alcohols to secondary organic aerosol formation

Organosulfate (OSA) nanoparticles,as secondary organic aerosol (SOA) compositions,are ubiquitous in urban and rural environments.Hence,we systemically investigated the mechanisms and kinetics of aqueous-phase reactions of 1-butanol/1-decanol (BOL/DOL) and their roles in the formation of OSA nanoparticles by using quantum chemical and kinetic calculations.The mechanism results show that the aqueous-phase reactions of BOL/DOL start from initial protonation at alcoholic OH^(-)groups to form carbenium ions (CBs),which engage in the subsequent esterification or oligomerization reactions to form OSAs/organosulfites (OSIs) or dimers.The kinetic results reveal that dehydration to form CBs for BOL and DOL reaction systems is the rate-limiting step.Subsequently,about 18%of CBs occur via oligomerization to dimers,which are difficult to further oligomerize because all reactive sites are occupied.The rate constant of BOL reaction system is one order of magnitude larger than that of DOL reaction system,implying that relative short-chain alcohols are more prone to contribute OSAs/OSIs than long-chain alcohols.Our results reveal that typical long-chain alcohols contribute SOA formation via esterification rather than oligomerization because OSA/OSI produced by esterification engages in nanoparticle growth through enhancing hygroscopicity.

粤港澳大湾区CO_(2)排放趋势、驱动因素及减排路径

粤港澳大湾区是我国为建设世界级城市群提出的国家战略,其CO_(2)排放趋势、社会经济驱动因素和减排路径对区域经济高质量发展具有重要意义。本研究编制了2000-2019年粤港澳大湾区CO_(2)排放清单,采用对数平均迪氏指数法探究CO_(2)排放的关键驱动力。结果表明,粤港澳大湾区CO_(2)排放在2017年后明显放缓,已经与国内生产总值(GDP)增长脱钩。经济增长和能源强度分别是驱动和抑制粤港澳大湾区CO_(2)排放增加的主要因素。能源生产和重工业对粤港澳大湾区CO_(2)排放增长的推动作用降低,服务业正成为主要驱动力。粤港澳大湾区通过产业结构调整和升级实现低碳发展取得了显著成效。深圳和香港地区的产业升级以及深圳、广州和佛山的技术进步抑制了粤港澳大湾区CO_(2)排放增长。粤港澳大湾区各城市异质性增加了减排指标分配难度和制定区域碳中和路线图的复杂性。本研究提出了粤港澳大湾区城市分级减排策略和碳达峰碳中和建议,为制定粤港澳大湾区城市碳达峰和碳中和行动方案以及其他城市和地区的低碳发展提供了科学依据。

A new method of simultaneous determination of atmospheric amines in gaseous and particulate phases by gas chromatography-mass spectrometry

As more attention is being paid to the characteristics of atmospheric amines,there is also an increasing demand for reliable detection technologies.Herein,a method was developed for simultaneous detection of atmospheric amines in both gaseous and particulate phases using gas chromatography-mass spectrometry(GC-MS).The amine samples were collected with and without phosphoric acid filters,followed by derivatization with benzenesulfonyl chloride under alkaline condition prior to GC-MS analysis.Furthermore,the method was optimized and validated for determining 14 standard amines.The detection limits ranged from0.0408-0.421μg/mL(for gaseous samples)and 0.163-1.69μg/mL(for particulate samples),respectively.The obtained recoveries ranged from 68.8%-180%and the relative standard deviation was less than 30%,indicating high precision and good reliability of the method.Seven amines were simultaneously detected in gaseous and particulate samples in an industrial park using the developed method successfully.Methylamine,dimethylamine and diethylamine together accounted for 76.7%and 75.6%of particulate and gaseous samples,respectively.By comparing the measured and predicted values of gas-particle partition fractions,it was found that absorption process of aqueous phase played a more important role in the gas-partition of amines than physical adsorption.Moreover,the reaction between unprotonated amines and acid(aq.)in water phase likely promoted water absorption.Higher measured partition fraction of dibutylamine was likely due to the reaction with gaseous HCl.The developed method would help provide a deeper understanding of gas-particle partitioning as well as atmospheric evolution of amines.

Remediation of preservative ethylparaben in water using natural sphalerite:Kinetics and mechanisms

As a typical class of emerging organic contaminants(EOCs), the environmental transformation and abatement of preservative parabens have raised certain environmental concerns. However, the remediation of parabens-contaminated water using natural matrixes(such as, naturally abundant minerals) is not reported extensively in literature. In this study, the transformation kinetics and the mechanism of ethylparaben using natural sphalerite(NS) were investigated. The results show that around 63% of ethylparaben could be absorbed onto NS within 38 hr, whereas the maximum adsorption capacity was 0.45 mg/g under room temperature. High temperature could improve the adsorption performance of ethylparaben using NS. In particular, for the temperature of 313 K, the adsorption turned spontaneous. The well-fitted adsorption kinetics indicated that both the surface adsorption and intra-particle diffusion contribute to the overall adsorption process. The monolayer adsorption on the surface of NS was primarily responsible for the elimination of ethylparaben. The adsorption mechanism showed that hydrophobic partitioning into organic matter could largely govern the adsorption process, rather than the Zn S that was the main component of NS. Furthermore, the ethylparaben adsorbed on the surface of NS was stable, as only less than 2% was desorbed and photochemically degraded under irradiation of simulated sunlight for 5 days. This study revealed that NS might serve as a potential natural remediation agent for some hydrophobic EOCs including parabens, and emphasized the significant role of naturally abundant minerals on the remediation of EOCs-contaminated water bodies.

Competing pathways of cresol formation in toluene photooxidation:OH-toluene adducts react with NO_(2) or with O_(2)?

Methyl-hydroxy-cyclohexadienyl radicals(OTAs)are the key products of the photooxidation of toluene,with implications for the fate of toluene.Hence,we investigated the photooxidation mechanisms and kinetics of three main OTAs(o-OTA,m-OTA,and p-OTA)with NO_(2)using quantum chemical calculations as well as the fate of OTAs under the different concentration ratios of NO_(2)and O_(2).The mechanism results show that the pathway of Habstraction by NO_(2)to anti-HONO(anti-H-abstraction)is more favorable than the syn-Habstraction pathway,because the strong interaction between OTAs and NO_(2)is formed in the transition states of the anti-H-abstraction pathways.The branching ratios of the antiH-abstraction pathways are more than 99%in the temperature range of 216-298 K.The total rate constant of the OTA-NO_(2)reaction is 9.9×10^(-12)cm^(3)/(molecule·sec)at 298 K,which is contributed about 90%by o-OTA+NO_(2),and the main products are o-cresol and anti-HONO.The half-lives of the OTA-NO_(2)reaction in some polluted areas of China are 35 times longer than those of the OTA-O_(2)reaction.In the atmosphere,the NO_(2^(-))and O_(2^(-))initiated reactions of OTAs have the same ability to form cresols as[NO_(2)]is up to 142.1 ppmV,which is impossible to achieve.It implies that under the experimental condition,the[NO_(2)]/[O_(2)]should be controlled to be less than 7.8×10^(-5)to simulate real atmospheric oxidation of toluene.Our results reveal that for the photooxidation of toluene,the yield of cresol is not affected by the concentration of NO_(2)under the atmospheric environment.

Assessing the role of mineral particles in the atmospheric photooxidation of typical carbonyl compound

Mineral particles are ubiquitous in the atmosphere and exhibit an important effect on the photooxidation of volatile organic compounds(VOCs).However,the role of mineral particles in the photochemical oxidation mechanism of VOCs remains unclear.Hence,the photooxi-dation reactions of acrolein(ARL)with OH radical(OH)in the presence and absence of SiO_(2) were investigated by theoretical approach.The gas-phase reaction without SiO_(2) has two distinct pathways(H-abstraction and OH-addition pathways),and carbonyl-H-abstraction is the dominant pathway.In the presence of SiO_(2),the reaction mechanism is changed,i.e.,the dominant pathway from carbonyl-H-abstraction to OH-addition to carbonyl C-atom.The energy barrier of OH-addition to carbonyl C-atom deceases 21.33 kcal/mol when SiO_(2) is added.Carbonyl H-atom of ARL is occupied by SiO_(2) via hydrogen bond,and carbonyl C-atom is ac-tivated by SiO_(2).Hence,the main product changes from H-abstraction product to OH-adduct in the presence of SiO_(2).The OH-adduct exhibits a thermodynamic feasibility to yield HO_(2) radical and carboxylic acid via the subsequent reactions with O_(2),with implications for O 3 formation and surface acidity of mineral particles.

Daily exposure to low concentrations Tetrabromobisphenol A interferes with the thyroid hormone pathway in HepG2 cells

Tetrabromobisphenol A(TBBPA)is a flame retardant that adversely affects the environment and human health.The present study exposed HepG2 cells to low concentrations of TBBPA daily to investigate the changes in gene regulation,mainly related to pathways associated with the endocrine system.The quantitative polymerase chain reaction(qPCR)confirmed that prolonged exposure gradually activated the thyroid hormone and parathyroid hormone signaling pathways.The expression levels of genes related to the thyroid hormone signaling pathway were upregulated(1.15-8.54 times)after five generations of exposure to 1 and 81 nM TBBPA.Furthermore,co-exposure to 81 nM TBBPA and 0.5 nM thyroid hormone receptor antagonist for five generations significantly reduced the expression of thyroid hormone and parathyroid hormone receptors.Meanwhile,81 nM TBBPA inhibited the activation of the Ras pathway and downregulated Ras gene expression level(3.7 times),indicating the association between the toxic effect and thyroid hormone receptors.Additionally,our experiments revealed that the thyroid hormone pathway regulated the induction of the Ras signaling pathway by TBBPA.The study thus proves that daily exposure to TBBPA interferes with the thyroid hormone signaling pathway and subsequently the endocrine system.

高排放城市在中国公平低碳转型中的杠杆效应

中国城市在全球碳减排中扮演着核心角色,然而中国城市间巨大的经济发展差异深刻影响了中国城市减排的进程.城际供应链连接了城市的生产和消费,被认为是塑造地区分化和减排疲软的因素之一,但该效应在先前的研究中往往没有得到充分的考虑.本文对2012年中国309个城市的供应链进行建模.利用该模型,我们揭示了城市间存在显著的碳不平等:中国最富裕的10个城市的人均碳足迹相当于美国的水平,而中国一半的城市则低于全球平均水平.然而,这种显著的碳不平等也蕴含着新的减排机遇,即对32个超高排放城市,根据其富裕程度、产业结构和供应链的位置采取不同的减排策略,将可创造高达1.4亿吨的碳配额,距离碳达峰值增加了30%的空间.额外的碳配额足够使经济发展欠发达人口的平均生活水平达到中上收入水平,突出了城市层面的合作机制具有促进公平和减排目标收敛的巨大潜力.

中国地级及以上城市碳排放达峰及驱动力分析

中国在推进全球气候变化减缓中扮演着重要的角色.以城市为单位的碳排放趋势和达峰模式研究可为中国碳排放达峰目标的兑现与低碳转型路线的落地提供支撑.本研究编制了中国287个地级及以上城市2001~2019年二氧化碳排放清单,涵盖47个社会经济部门、17种化石燃料燃烧和水泥生产过程相关排放,并探究了各城市的碳排放达峰状态及其驱动力.结果表明,截至2019年,全国共有59个地级及以上城市出现了碳排放的持续下降,其中38个城市为主动达峰型,21个城市则是被动下降型.38个主动达峰城市碳减排的主要驱动力为能源效率提高和能源结构调整,而21个被动下降城市的碳减排在一定程度上是由经济衰退或人口流失所导致的.未来,排放被动下降城市应抓住低碳目标带来的产业创新和绿色投资机遇,瞄准经济复苏和碳减排目标,实现排放与经济发展的强脱钩;主动达峰城市则应进一步探寻碳排放下降趋势的长久维持策略,为未达峰城市提供成功经验.