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91.
Sofia Batista Emília Silva Sara Galhardo Paula Viana Maria José Cerejeira 《International journal of environmental analytical chemistry》2013,93(8-9):601-609
In two Portuguese agricultural areas, "Beira Litoral" and "Ribatejo e Oeste", several pesticides regularly applied in vineyards, maize, potato, tomato for industry, apple, pear and rice were detected in ground water. Atrazine was the most frequently detected, being found in 70% of the total of 79 sites selected in the year 2000, followed by its metabolites desethylatrazine and desisopropylatrazine with frequencies of detection, respectively, of 56% and 48% and by simazine (37%), alachlor (25%), metolachlor (24%) and metribuzin (15%). Other pesticides and metabolites i.e. 3,4-dichloroaniline, dimethoate, f and g -endosulfan, lindane, molinate and prometryn were also detected but at lower occurrences. Pesticides were detected mainly in ground water wells used for irrigation purposes, although in some locations they were also found in water wells used for human consumption. In this study, it was also observed a seasonal variation of pesticide residues in ground water of shallow and deep wells. 相似文献
92.
Synthesis and computational study of two new glycoluril clips containing benzocrown ether side walls
Esmail Rezaei-Seresht Sirous Salemi Mahnaz Ahmadi Sara Taghizadeh 《Journal of inclusion phenomena and macrocyclic chemistry》2013,76(1-2):69-74
Two new glycoluril-derived molecular clips containing benzocrown ether side walls have been synthesized via reaction of a glycoluril scaffold with two bromomethylated benzocrown ethers. The molecular geometry of their most stable structures were investigated with density functional theory at the B3LYP level of theory using STO-3G, 6-31G, and 6-311G basis sets. Then based on the obtained computer-optimized structures, the binding properties of one clip with some 5-substituted resorcinols have been calculated. 相似文献
93.
Esmail Rezaei-Seresht Sirous Salemi Sara Taghizadeh Mehri Ghorbani 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):403-411
Several new clip-shaped molecules, with different degrees of steric hindrance around their cavities as well as more rigidity on their glycoluril scaffold, have been synthesized and the molecular geometry of their most stable structures has been investigated and optimized with density functional theory (DFT) at the B3LYP level of theory using 6-311G basis set. The affinity of these molecular clips for some dihydroxybenzene derivatives (guests) has been computationally and experimentally studied. The clips having dimethyl-substituted aromatic side walls, showed the best interaction energies towards the mentioned guests. Also, the computational results revealed that the more electron-deficient guest interacts more strongly with the clips (hosts). 相似文献
94.
Dr. Chandi C. Malakar Dr. Sara Stas Prof. Dr. Wouter Herrebout Prof. Dr. ir. Kourosch Abbaspour Tehrani 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(42):14263-14270
A variety of N‐alkyl‐α,α‐dichloroaldimines were vinylated by terminal acetylenes in the presence of Lewis acids such as In(OTf)3 or BF3 ? OEt2 and hexafluoroisopropanol (HFIP) as an additive. The reaction proceeds at ambient temperature and leads to geometrically pure allylic β,β‐dichloroamines. This approach is complementary to previously reported transition‐metal‐catalyzed vinyl‐transfer methods, which are not applicable to aliphatic imines and are restricted to imines that contain an electron‐withdrawing nitrogen substituent. In the present approach, terminal alkynes were used as a source of the vinyl residue, and the N‐alkyl moiety of the imine acts as a sacrificial hydrogen donor. The additional advantage of this methodology is the fact that no external toxic or hazardous reducing agents or molecular hydrogen has to be used. This new methodology nicely combines a C(sp2)? C(sp) bond formation, hydride transfer, and an unusual cleavage of an unactivated C? N bond, thereby giving rise to functionalized primary allylic amines. A detailed experimental study supported by DFT calculations of the mechanism has been done. 相似文献
95.
96.
Analysis of xylene in aqueous media using needle‐trap microextraction with a carbon nanotube sorbent 下载免费PDF全文
Sara Karimi Zeverdegani Abdulrahman Bahrami Masoud Rismanchian Farshid Ghorbani Shahna 《Journal of separation science》2014,37(14):1850-1855
This paper describes a new extraction technique with needles and a sorbent based on carbon nanotubes to analyze trace amounts of three isomers of xylenes in aqueous samples. In this research, results have been compared with one commercial sorbent. The synthesized sorbent was prepared using sol–gel technology and was packed into 20 gauge needles, and the same size needle was used for packing the commercial sorbent. In the extraction process, a purge and trap sampling methodology is developed, so purging and trapping cycles were performed by a sampling pump. Optimized conditions for standard xylene samples have been obtained, and eight urine samples from workers that were exposed to xylene in the workplace were collected and analyzed. Experimental parameters such as limits of detection and quantification were investigated, and these two parameters were <1 μg/L. 相似文献
97.
Recently, it has been shown that by using a single‐site catalytic system having titanium as a metallic center, it is possible to tailor the entanglement density in the amorphous region of a semi‐crystalline ultra‐high molecular weight polyethylene (UHMWPE). This route provides the possibility to make high‐modulus, high‐strength uniaxially and biaxially drawn tapes and films, without using any solvent during processing. In this publication, it is shown that a single‐site catalyst having chromium as metallic center, proposed by Enders and co‐workers, can also be tuned to provide control on the entanglement density during synthesis of the UHMWPE. However, to achieve the goal some modifications during the synthesis are required. The synthesized polymers can be processed in the solid state below the equilibrium melting temperature, resulting in uniaxially drawn tapes having tensile strength and modulus greater than 3.5 N/tex and 200 N/tex, respectively. Rheological studies have been performed to follow the increase in entanglement density in melt state with time.
98.
Vnia S. F. Muralha Sara Canaveira Jos Miro Susana Coentro Teresa Morna Carlo Stefano Salerno 《Journal of Raman spectroscopy : JRS》2015,46(5):483-492
For the first time, 18th‐century glass mosaics from the Capela de São João Baptista (Chapel of St. John the Baptist, Lisbon) were analysed by Raman microscopy (RM). This masterpiece in baroque mosaic art had one of its major contributors the most famous glassmaker in Rome, Alessio Mattioli. Mattioli was celebrated because of the opacity of his mosaics and the astonishing number of hues he was able to produce for mosaic decorating Saint Peter's Basilica in Rome. This study had two goals in mind: (1) characterising the materials involved in the manufacture of these glass mosaics and (2) lengthening the understanding of what was left of Mattioli's glassmaking records. As expected the mosaics presented a high ratio of crystalline phases, making RM the ideal technique for non‐destructive analysis. The mosaics contained a white ‘background’ or opacifier added identified as Ca2Sb2O7. The yellow tesserae are opacified with lead antimonate (Pb2Sb2O7) and ternary oxides, structures related to lead antimonate but with other ions entering the position of Sb4+ (namely Sn4+). Those ternary oxides are pervasive in most colours, admixed with other colorants. The red, orange, pink and brown colours were accomplished with cuprous oxide (Cu2O) and admixed with a ternary oxide to create the latter three colours. The red copper‐based colours were made according to the procedure to make a ruby copper glass and with the exception of the red colour; all mosaics exhibited a dark layer on each side of the mosaic, named scorzetta. This layer is the outcome of an oxidation reaction because of a quick cooling process and is composed of CuO. Finally the blue and green colours are accomplished with cobalt oxide and copper oxide, respectively, and the purple/black colour with manganese oxide. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
99.
Hadisi Maliheh Vosoughi Naser Yousefnia Hassan Bahrami-Samani Ali Zolghadri Samaneh Vosoughi Sara Alirezapour Behrouz 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(2):841-849
Journal of Radioanalytical and Nuclear Chemistry - In this study, optimized preparation, quality control, cell assessments and biostribution of 188Re-HYNIC-PSMA in normal rats and tumor bearing... 相似文献
100.
Sajadpour Maryam Abbasian Sara Siampour Hossein Bagheri Hasan Moshaii Ahmad 《Journal of Solid State Electrochemistry》2022,26(1):149-161
Journal of Solid State Electrochemistry - A facile and sensitive approach is introduced to precisely determine trace amounts of prostate specific antigen (PSA) by gold nanostructures deposited on... 相似文献