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Yuan Yang, Li Luo, Hai-Pu Li, Qiang Wang, Zhao-Guang Yang, Chen-Lu Long
In this study, cloud point extraction (CPE) combined inductively coupled plasma mass spectrometry (ICP-MS) was used to determinate silver nanoparticles (AgNPs) in environmental water. AgNPs dispersed in water could be extracted into surfactant phase based on optimized CPE parameters which including pH, incubation temperature and equilibration time, the content of nonionic surfactants (Triton X-114, TX-114) and Na2S3O3. Good separation results of AgNPs and ionic silver Ag(I) in aqueous environment was obtained with the addition of Na2S3O3 when the concentration of Ag(I) was lower than ten times of AgNPs...
December 1, 2016: Talanta
Wei Huang, Ying-Jie Yang, Hong Hu, Shi-Bao Zhang
Low temperature associated with high light can induce photoinhibition of photosystem I (PSI) and photosystem II (PSII). However, the photosynthetic electron flow and specific photoprotective responses in alpine evergreen broad-leaf plants in winter is unclear. We analyzed seasonal changes in PSI and PSII activities, and energy quenching in PSI and PSII in three alpine broad-leaf tree species, Quercus guyavifolia (Fagaceae), Rhododendron decorum (Ericaceae), Euonymus tingens (Celastraceae). In winter, PSII activity remained stable in Q...
October 13, 2016: Journal of Photochemistry and Photobiology. B, Biology
Fang-Fang Shen, Kai Chen, Yun-Qian Zhang, Qian-Jiang Zhu, Zhu Tao, Hang Cong
Mono- and dihydroxylated symmetrical octamethylcucurbit[6]urils {(OH)OMeQ[6] and (OH)2OMeQ[6]} were prepared using a photochemical method to introduce limited alcohol group(s) directly to the parent symmetrical octamethylcucurbit[6]uril (OMeQ[6]), and the resulting compounds were verified by (1)H NMR, Xevo Q-TOF MS, and X-ray crystallography. Further chemical modification of mono- and dihydroxylated OMeQ[6] was also performed.
October 21, 2016: Organic Letters
Jesús Ignacio Mendieta-Moreno, Daniel G Trabada, Jesus Mendieta, James P Lewis, Paulino Gómez-Puertas, Jose Ortega
The absorption of ultraviolet radiation by DNA may result in harmful genetic lesions that affect DNA replication and transcription, ultimately causing mutations, cancer and/or cell death. We analyze the most abundant photochemical reaction in DNA, the cyclobutane thymine dimer, using hybrid quantum mechanics / molecular mechanics (QM/MM) techniques and QM/MM nonadiabatic molecular dynamics. We find that, due to its double helix structure, DNA presents a free energy barrier between non-reactive and reactive conformations leading to the photolesion...
October 21, 2016: Journal of Physical Chemistry Letters
Benoît Roubinet, Mariano L Bossi, Philipp Alt, Marcel Leutenegger, Heydar Shojaei, Sebastian Schnorrenberg, Shamil Nizamov, Masahiro Irie, Vladimir N Belov, Stefan W Hell
Reversibly photoswitchable 1,2-bis(2-ethyl-6-phenyl-1-benzothiophene-1,1-dioxide-3-yl)perfluorocyclopentenes (EBT) having fluorescent "closed" forms were decorated with four or eight carboxylic groups and attached to antibodies. Low aggregation, efficient photoswitching in aqueous buffers, specific staining of cellular structures, and good photophysical properties were demonstrated. Alternating light pulses of UV and blue light induce numerous reversible photochemical transformations between two stables states with distinct structures...
October 21, 2016: Angewandte Chemie
Alina Tirla, Pablo Rivera-Fuentes
Photoactivatable phosphines that induce intracellular reductive stress are reported. The design of these probes takes advantage of the conjugate addition of trialkylphosphines to carbocyanine dyes, which can be reverted photochemically to produce the trialkylphosphine and a fluorescent reporter. The photochemical release depends on the efficiency of photoinduced electron transfer from the indolenine arm of the probe to the coumarin acceptor. These probes readily permeate the mammalian plasma membrane and can be photoactivated in live cells...
October 20, 2016: Angewandte Chemie
Tiele Caprioli Machado, Marla Azário Lansarin
The hexavalent chromium, Cr(VI), which is generated in the electroplating process, is toxic to most organisms and potentially harmful to human health. The method generally used for remediation of wastewater containing Cr(VI) employs chemicals with high toxicity. This work proposes an alternative technology for the treatment of these wastewaters, based on photochemical reduction of Cr(VI) by alcohols under radiation, which is environmentally sustainable and economically viable. Initially, a batch reactor in laboratory scale was used to determine the best experimental conditions and its specific reaction rate was calculated...
October 2016: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Emanuel Carlos, Rita Branquinho, Asal Kiazadeh, Pedro Barquinha, Rodrigo Martins, Elvira Fortunato
Solution processing of amorphous metal oxides has been lately used as an option to implement in flexible electronics allowing a reduction of the associated costs and high performance. However the research has focused more on semiconductor layer rather than on the insulator layer that is related to the stability and performance of the devices. This work aims to evaluate amorphous aluminum oxide thin films produced by combustion synthesis and the influence of far ultraviolet (FUV) irradiation on properties of the insulator on thin film transistors (TFTs) using different semiconductors, in order to have compatibility with flexible substrates...
October 20, 2016: ACS Applied Materials & Interfaces
Hongming He, Jason A Perman, Guangshan Zhu, Shengqian Ma
Carbon dioxide (CO2 ), as the primary greenhouse gas in the atmosphere, triggers a series of environmental and energy related problems in the world. Therefore, there is an urgent need to develop multiple methods to capture and convert CO2 into useful chemical products, which can significantly improve the environment and promote sustainable development. Over the past several decades, metal-organic frameworks (MOFs) have shown outstanding heterogeneous catalytic activity due in part to their high internal surface area and chemical functionalities...
October 20, 2016: Small
Junki Tanabe, Daisuke Taura, Naoki Ousaka, Eiji Yashima
The photoirradiation of 9-phenylethynylanthracene in degassed chloroform and benzene afforded not only a [4 + 2]-anti Diels-Alder addition dimer, but also a [4 + 4]-anti-dimer as a minor product for the first time as revealed by single-crystal X-ray analysis, while the anthracene residue was quantitatively oxidised in undegassed dilute chloroform, giving the corresponding endoperoxides. The photochemical reactions of carboxylic acid monomers bearing a 9-phenylethynylanthracene unit at one and both ends were further investigated in the presence and absence of the complementary amidine dimer as the template...
October 20, 2016: Organic & Biomolecular Chemistry
Yuma Hakoda, Masatoshi Aoyagi, Ken-Ichi Irisawa, Shin-Ichiro Kato, Yosuke Nakamura, Minoru Yamaji
Phenanthrenes substituted with trimethylsilylethynyl and phenylethynyl groups were photochemically prepared, and their photophysical properties were systematically investigated based on measurements of fluorescence quantum yields, lifetimes, and transient absorption. Introducing ethynyl groups into the phenanthrene skeleton caused an increase in the fluorescence quantum yields compared to that of phenanthrene. The quantum yields and rates of fluorescence were dependent on the substituting position(s) and the terminating group for the C-C triple bond...
October 20, 2016: Photochemical & Photobiological Sciences
Bart Van den Bogaert, Lore Gheeraert, Mumin Enis Leblebici, Koen Binnemans, Tom Van Gerven
The photochemical recovery of europium from non-aqueous media, more specifically alcohols, is studied. The recovery was performed by photochemical reduction of europium(iii) to europium(ii) and subsequent removal as the insoluble EuCl2. Two charge transfer bands are present in the UV-C region, one originating from the alcohol (around 230 nm) and the other from the chloride anion (at 271 nm), which are responsible for the photochemical reduction when the solution is illuminated by a medium-pressure mercury lamp...
October 20, 2016: Physical Chemistry Chemical Physics: PCCP
Zhe Lv, Nasir Mahmood, Muhammad Tahir, Lun Pan, Xiangwen Zhang, Ji-Jun Zou
Transition metal dichalcogenides (TMDs) are emerging as promising materials, particularly for electrochemical and photochemical catalytic applications, and among them molybdenum sulfides have received tremendous attention due to their novel electronic and optoelectronic characteristics. Several review articles have summarized the recent progress on TMDs but no critical and systematic summary exists about the nanoscale fabrication of MoS2 with different dimensional morphologies. In this review article, first we will summarize the recent progress on the morphological tuning and structural evolution of MoS2 from zero-dimension (0D) to 3D...
October 20, 2016: Nanoscale
Jing Zhang, Huibin Li, Bin Xu, Jing Li, Bingru Huang
Leaf senescence is a typical symptom in plants exposed to dark and may be regulated by plant growth regulators. The objective of this study was to determine whether exogenous application of melatonin (N-acetyl-5-methoxytryptamine) suppresses dark-induced leaf senescence and the effects of melatonin on reactive oxygen species (ROS) scavenging system and chlorophyll degradation pathway in perennial grass species. Mature perennial ryegrass (Lolium perenne L. cv. 'Pinnacle') leaves were excised and incubated in 3 mM 2-(N-morpholino) ethanesulfonic buffer (pH 5...
2016: Frontiers in Plant Science
Robert N Goldstone, Michael C McCormack, Rachel L Goldstein, Srivalleesha Mallidi, Mark A Randolph, Michael T Watkins, Robert W Redmond, William G Austen
OBJECTIVE: We hypothesized that decreasing vein compliance would protect the vein against stretch injury and reduce intimal hyperplasia (IH). BACKGROUND: Although arteriovenous fistulas (AVFs) are the criterion standard for vascular access, their effectiveness is limited by poor patency with 40% to 60% failing due to IH. Venous stretch injury from exposure to arterial pressure induces IH. Photochemical tissue passivation (PTP) crosslinks adventitial collagen, decreasing vein compliance to resemble that of an artery...
October 17, 2016: Annals of Surgery
Anders Sandell, Davide Ragazzon, Andreas Schaefer, Mari Helene Farstad, Anne Borg
We present a dedicated synchrotron radiation photoelectron spectroscopy (SR-PES) study of a photochemical reaction on the surface of rutile TiO2(110). The photoreaction kinetics of carboxylate species (trimethyl acetate, TMA) upon irradiation by UV and soft x-rays were monitored and we show that it is possible to control the reaction rates from UV light and soft x-rays independently. We directly observe Ti4+ → Ti3+ conversion upon irradiation, attributed to electron trapping at Ti sites close to surface OH groups formed by deprotonation of the parent molecule, trimethyl acetic acid (TMAA)...
October 18, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Atanu Acharya, Alexey M Bogdanov, Bella L Grigorenko, Ksenia B Bravaya, Alexander V Nemukhin, Konstantin A Lukyanov, Anna I Krylov
Photoinduced reactions play an important role in the photocycle of fluorescent proteins from the green fluorescent protein (GFP) family. Among such processes are photoisomerization, photooxidation/photoreduction, breaking and making of covalent bonds, and excited-state proton transfer (ESPT). Many of these transformations are initiated by electron transfer (ET). The quantum yields of these processes vary significantly, from nearly 1 for ESPT to 10(-4)-10(-6) for ET. Importantly, even when quantum yields are relatively small, at the conditions of repeated illumination the overall effect is significant...
October 18, 2016: Chemical Reviews
Gang Li, David Talmy, Douglas A Campbell
Light drives phytoplankton productivity, so phytoplankton must exploit variable intensities and durations of light exposure, depending upon season, latitude and depth. We analyzed the growth, photophysiology and composition of small, Thalassiosira pseudonana, and large, Thalassiosira punctigera, centric diatoms from temperate, coastal marine habitats, responding to a matrix of photoperiods and growth light intensities. T. pseudonana showed fastest growth rates under long photoperiods and low to moderate light intensities, while the larger T...
October 18, 2016: Journal of Phycology
Amineh Aghabali, Sharon Jun, Marilyn M Olmstead, Alan L Balch
The photochemical reaction of piperazine with C70 produces a mono adduct (N(CH2CH2)2NC70) in high yield (67%) and three bis-adducts. These adducts combine with Lewis acids to form crystalline aggregates suitable for X-ray diffraction. The structure of (N(CH2CH2)2NC70) was determined from the adduct that formed by reaction of N(CH2CH2)2NC70 with I2. Crystals of polymeric {Rh2(O2CCF3)4N(CH2CH2)2NC70}n*nC6H6 from reaction of the mono adduct with Rh2(O2CCF3)4 contain a sinusoidal strand of alternating molecules of N(CH2CH2)2NC70 and Rh2(O2CCF3)4 connected through Rh-N bonds...
October 17, 2016: Chemistry: a European Journal
S Binita Chanu, Samya Banerjee, Mithun Roy
Cancer-specific anticancer drugs are still an elusive goal. Using light as the temporal control to generate cytotoxic species from photo-activated prodrug in the presence or absence of molecular oxygen has shown potential application targeted chemotherapy as in photodynamic therapy (PDT). In the present work we explored the chemistry of several photo-active (μ-oxo)diiron(III) complexes of the following formulation [{Fe(μ-O) (L-his)(B)}2](ClO4)2 (1a-1c), [Fe2(μ-O)(H2O)2B4](ClO4)4 (2b, 2c) and [Fe2(μ-O)(μ-O2CMe)B4](ClO4)3 (3b, 3c), L-his = l-histidine, B is 2,2'-bipyridine, 1,10-phenanthroline (phen) and dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) complexes for tumor-specific anticancer activity...
September 28, 2016: European Journal of Medicinal Chemistry
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