The rapidly increasing implementations of oilfield technologies such as horizontal wells and multistage hydraulic fracturing,particularly in unconventional formations,have expanded the need for fresh water in many oil...The rapidly increasing implementations of oilfield technologies such as horizontal wells and multistage hydraulic fracturing,particularly in unconventional formations,have expanded the need for fresh water in many oilfield locations.In the meantime,it is costly for services companies and operators to properly dispose large volumes of produced water,generated annually at about 21 billion barrels in the United States alone.The high operating costs in obtaining fresh water and dealing with produced water have motivated scientists and engineers,especially in recent years,to use produced water in place of fresh water to formulate well treatment fluids.The objective of this brief review is to provide a summary of the up-to-date technologies of reusing oilfield produced water in preparations of a series of crosslinked fluids implemented mainly in hydraulic fracturing operations.The crosslinked fluids formulated with produced water include borate-and metalcrosslinked guar and derivatized guar fluids,as well as other types of crosslinked fluid systems such as crosslinked synthetic polymer fluids and crosslinked derivatized cellulose fluids.The boratecrosslinked guar fluids have been successfully formulated with produced water and used in oilfield operations with bottomhole temperatures up to about 250F.The produced water sources involved showed total dissolved solids(TDS)up to about 115,000 mg/L and hardness up to about 11,000 mg/L.The metal-crosslinked guar fluids prepared with produced water were successfully used in wells at bottomhole temperatures up to about 250F,with produced water TDS up to about 300,000 mg/L and hardness up to about 44,000 mg/L.The Zr-crosslinked carboxymethyl hydroxypropyl guar(CMHPG)fluids have been successfully made with produced water and implemented in operations with bottomhole temperatures at about 250tF,with produced water TDS up to about 280,000 mg/L and hardness up to about 91,000 mg/L.In most of the cases investigated,the produced water involved was either untreated,or the treatments展开更多
Modified deoxy-and ribo-nucleoside triphosphates are chemically synthesized in multiple steps due to the protection and deprotection of the nucleoside functionalities.To conveniently synthesize the S-modified triphosp...Modified deoxy-and ribo-nucleoside triphosphates are chemically synthesized in multiple steps due to the protection and deprotection of the nucleoside functionalities.To conveniently synthesize the S-modified triphosphates for enzymatically preparing phosphorothioate DNAs and RNAs(PS-DNA and PS-RNA) as potential therapeutics,herein we report a one-pot strategy to synthesize the deoxy-and ribo-nucleoside 5'-(α-P-thio)triphosphates(dNTPαS and NTPαS) without protecting any nucleoside functionalities.This facile synthesis is achieved by treating the nucleosides with a mild phosphitylating reagent,reacting selectively with the 5'-hydroxyl group of each unprotected nucleoside,followed by sulfurization and hydrolysis to afford the crude dNTPαS and NTPαS analogs(mixtures of Sp and Rp diastereomers).We also demonstrated that after just simple precipitation(without HPLC and ion-exchange purification),the quality of the synthesized dNTPαS and NTPαS analogs is excellent for direct DNA polymerization and RNA transcription,respectively.Since Klenow DNA polymerase and T7 RNA polymerase accept the Sp diastereomers of dNTPαS and NTPαS analogs,respectively,while the Rp diastereomers are neither substrates nor inhibitors,the diastereomerically-pure PS-DNAs and PS-RNAs can be conveniently synthesized enzymatically.展开更多
Chiral alcohols（3, 5） were synthesized in optically pure forms from easily available rosin acid in short-steps. A comprehensive protocol for the enantiomeric excess assays of mono- or di-functional-grouped chiral se...Chiral alcohols（3, 5） were synthesized in optically pure forms from easily available rosin acid in short-steps. A comprehensive protocol for the enantiomeric excess assays of mono- or di-functional-grouped chiral secondary amine or alcohol has been established with them used as chiral auxiliary for chiral phosphorus derivatizing agents（CPDAs） in 3Jp NMR tests. Chemical shift difference（△δp） values ranging from 4.5 to 0.15 between two dias- tereoisomers of the CPDAs and the aryl substrates were obtained. Positive △δR-S was observed for all the tested alco- hol P（III） and P（V） derivatives, while negative △δR-S was observed for all the amines.展开更多
The experimental solubility of CBZ (Carbobenzoxy) derivatized amino acids namely N-CBZ valine, N-CBZ proline, N-CBZ aspartic acid in supercritical carbon dioxide were correlated by Soave-Red- lich-Kwong Equation state...The experimental solubility of CBZ (Carbobenzoxy) derivatized amino acids namely N-CBZ valine, N-CBZ proline, N-CBZ aspartic acid in supercritical carbon dioxide were correlated by Soave-Red- lich-Kwong Equation state based on fugacity determination and group contribution method using extrapolated critical parameters and mixing rules and other two different empirical models proposed by Yu (1994) and Gordillo-coworkers (1999). The SRK EOS prediction showed very high deviation of % AARD of 9% - 59%. The Yu model had three derivatized amino acids with average absolute deviation from 2.04, 8.17, 10.96, while the Gordillo model had 0.245, 1.067 and 1.144 for CBZ-valine, CBZ-proline and CBZ-aspartic acid successively. The correlated values had better fit with Gordillo model. The predictive capability and applicability for these amino acid derivatives for both the models demonstrated with correlation coefficient around 0.99 for all the experimental solubility observed.展开更多
<span style="font-family:Verdana;">Chemical investigation of the MeOH extract from the leaves of </span><i><span style="font-family:Verdana;">C.</span></i> <i...<span style="font-family:Verdana;">Chemical investigation of the MeOH extract from the leaves of </span><i><span style="font-family:Verdana;">C.</span></i> <i><span style="font-family:Verdana;">glauca</span></i> <span><span style="font-family:Verdana;">yielded nine known triterpenoids (</span><b><span style="font-family:Verdana;">1-9</span></b><span style="font-family:Verdana;">) belonging to the cycloartane and</span></span><span style="font-family:Verdana;"> friedelane series. Two of these compounds namely glaucartanoic acid A (</span><b><span style="font-family:Verdana;">1</span></b><span style="font-family:Verdana;">) and 3</span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">,21</span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">-dihydroxy-30-nor-(D:A)-friedoolean-20(29)-en-27-oic acid (</span><b><span style="font-family:Verdana;">5</span></b><span style="font-family:Verdana;">) were subjected to chemical derivatizations and afforded five new derivatives: diacetylglaucartanoic acid A (</span><b><span style="font-family:Verdana;">1a</span></b><span style="font-family:Verdana;">), 24-acetylglaucartanoic acid A (</span><b><span style="font-family:Verdana;">1b</span></b><span style="font-family:Verdana;">), glaucartanoic acid A methyl ester (</span><b><span style="font-family:Verdana;">1c</span></b><span style="font-family:Verdana;">), 24-methoxyglaucartanoic acid A methyl </span><span><span style="font-family:Verdana;">ester (</span><b><span style="font-family:Verdana;">1d</span></b><span style="font-family:Verdana;">), and 3</span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">,21</span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">-diacetoxy-30-nor-(D:A)-friedoolean-20(29)-en-27-oic</span></span><span style="font-family:Verdana;"> acid (</span><b><span style="font-family:Verdana;">5a</span></b><span style="font-family:Verdana;">). Their structures were 展开更多
在食品加工过程中,美拉德反应虽然对提升食品的风味和品质具有重要作用,但也会衍生一些化学危害物。本文综述了美拉德反应对食品风味和色泽等品质的影响,以及美拉德反应产物的抗氧化和抗突变等特性,同时也探讨了美拉德反应产生的丙烯酰...在食品加工过程中,美拉德反应虽然对提升食品的风味和品质具有重要作用,但也会衍生一些化学危害物。本文综述了美拉德反应对食品风味和色泽等品质的影响,以及美拉德反应产物的抗氧化和抗突变等特性,同时也探讨了美拉德反应产生的丙烯酰胺(acrylamide,AA)、杂环胺(heterocyclic amines,HAs)和晚期糖基化末端终产物(advanced glycation end products,AGEs)等化学危害物的生成机制、分析和抑制方法。由于3类危害物在食品中的含量较低(ng/g~μg/g)且基质非常复杂,因此其检测均需要采用固相萃取等方法进行分离富集,随后可采用超高效液相色谱串联质谱(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)等方法进行定性定量分析。危害物的抑制主要通过采用更加温和的加工方法、调整工艺参数和添加香辛料及酚类等天然抗氧化物质来实现。展开更多
文摘The rapidly increasing implementations of oilfield technologies such as horizontal wells and multistage hydraulic fracturing,particularly in unconventional formations,have expanded the need for fresh water in many oilfield locations.In the meantime,it is costly for services companies and operators to properly dispose large volumes of produced water,generated annually at about 21 billion barrels in the United States alone.The high operating costs in obtaining fresh water and dealing with produced water have motivated scientists and engineers,especially in recent years,to use produced water in place of fresh water to formulate well treatment fluids.The objective of this brief review is to provide a summary of the up-to-date technologies of reusing oilfield produced water in preparations of a series of crosslinked fluids implemented mainly in hydraulic fracturing operations.The crosslinked fluids formulated with produced water include borate-and metalcrosslinked guar and derivatized guar fluids,as well as other types of crosslinked fluid systems such as crosslinked synthetic polymer fluids and crosslinked derivatized cellulose fluids.The boratecrosslinked guar fluids have been successfully formulated with produced water and used in oilfield operations with bottomhole temperatures up to about 250F.The produced water sources involved showed total dissolved solids(TDS)up to about 115,000 mg/L and hardness up to about 11,000 mg/L.The metal-crosslinked guar fluids prepared with produced water were successfully used in wells at bottomhole temperatures up to about 250F,with produced water TDS up to about 300,000 mg/L and hardness up to about 44,000 mg/L.The Zr-crosslinked carboxymethyl hydroxypropyl guar(CMHPG)fluids have been successfully made with produced water and implemented in operations with bottomhole temperatures at about 250tF,with produced water TDS up to about 280,000 mg/L and hardness up to about 91,000 mg/L.In most of the cases investigated,the produced water involved was either untreated,or the treatments
基金supported by USA NIH(GM095086)the Georgia Cancer Coalition(GCC) Distinguished Cancer Clinicians and ScientistsUSA National Science Foundation(MCB-0824837)
文摘Modified deoxy-and ribo-nucleoside triphosphates are chemically synthesized in multiple steps due to the protection and deprotection of the nucleoside functionalities.To conveniently synthesize the S-modified triphosphates for enzymatically preparing phosphorothioate DNAs and RNAs(PS-DNA and PS-RNA) as potential therapeutics,herein we report a one-pot strategy to synthesize the deoxy-and ribo-nucleoside 5'-(α-P-thio)triphosphates(dNTPαS and NTPαS) without protecting any nucleoside functionalities.This facile synthesis is achieved by treating the nucleosides with a mild phosphitylating reagent,reacting selectively with the 5'-hydroxyl group of each unprotected nucleoside,followed by sulfurization and hydrolysis to afford the crude dNTPαS and NTPαS analogs(mixtures of Sp and Rp diastereomers).We also demonstrated that after just simple precipitation(without HPLC and ion-exchange purification),the quality of the synthesized dNTPαS and NTPαS analogs is excellent for direct DNA polymerization and RNA transcription,respectively.Since Klenow DNA polymerase and T7 RNA polymerase accept the Sp diastereomers of dNTPαS and NTPαS analogs,respectively,while the Rp diastereomers are neither substrates nor inhibitors,the diastereomerically-pure PS-DNAs and PS-RNAs can be conveniently synthesized enzymatically.
基金Supported by the National Basic Research Program of China（No.2011CB512005）, the National Natural Science Foundation of China（Nos.81260472 and 21101035）, Guangxi Natural Science Foundation of China（Nos.2011GXNSFD018010 and 2010GXNSFF013001）, the Project of Ten, Hundred, Thousand Distinguished Talents in New Century of Guangxi, China （No.2007228） and the State Key Laboratory Cultivation Base for the Chemistry and Molecular Engineering of Medicinal Resources, Ministry of Science and Technology of China （No.CMEMR2012-A14）.
文摘Chiral alcohols（3, 5） were synthesized in optically pure forms from easily available rosin acid in short-steps. A comprehensive protocol for the enantiomeric excess assays of mono- or di-functional-grouped chiral secondary amine or alcohol has been established with them used as chiral auxiliary for chiral phosphorus derivatizing agents（CPDAs） in 3Jp NMR tests. Chemical shift difference（△δp） values ranging from 4.5 to 0.15 between two dias- tereoisomers of the CPDAs and the aryl substrates were obtained. Positive △δR-S was observed for all the tested alco- hol P（III） and P（V） derivatives, while negative △δR-S was observed for all the amines.
文摘The experimental solubility of CBZ (Carbobenzoxy) derivatized amino acids namely N-CBZ valine, N-CBZ proline, N-CBZ aspartic acid in supercritical carbon dioxide were correlated by Soave-Red- lich-Kwong Equation state based on fugacity determination and group contribution method using extrapolated critical parameters and mixing rules and other two different empirical models proposed by Yu (1994) and Gordillo-coworkers (1999). The SRK EOS prediction showed very high deviation of % AARD of 9% - 59%. The Yu model had three derivatized amino acids with average absolute deviation from 2.04, 8.17, 10.96, while the Gordillo model had 0.245, 1.067 and 1.144 for CBZ-valine, CBZ-proline and CBZ-aspartic acid successively. The correlated values had better fit with Gordillo model. The predictive capability and applicability for these amino acid derivatives for both the models demonstrated with correlation coefficient around 0.99 for all the experimental solubility observed.
文摘<span style="font-family:Verdana;">Chemical investigation of the MeOH extract from the leaves of </span><i><span style="font-family:Verdana;">C.</span></i> <i><span style="font-family:Verdana;">glauca</span></i> <span><span style="font-family:Verdana;">yielded nine known triterpenoids (</span><b><span style="font-family:Verdana;">1-9</span></b><span style="font-family:Verdana;">) belonging to the cycloartane and</span></span><span style="font-family:Verdana;"> friedelane series. Two of these compounds namely glaucartanoic acid A (</span><b><span style="font-family:Verdana;">1</span></b><span style="font-family:Verdana;">) and 3</span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">,21</span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">-dihydroxy-30-nor-(D:A)-friedoolean-20(29)-en-27-oic acid (</span><b><span style="font-family:Verdana;">5</span></b><span style="font-family:Verdana;">) were subjected to chemical derivatizations and afforded five new derivatives: diacetylglaucartanoic acid A (</span><b><span style="font-family:Verdana;">1a</span></b><span style="font-family:Verdana;">), 24-acetylglaucartanoic acid A (</span><b><span style="font-family:Verdana;">1b</span></b><span style="font-family:Verdana;">), glaucartanoic acid A methyl ester (</span><b><span style="font-family:Verdana;">1c</span></b><span style="font-family:Verdana;">), 24-methoxyglaucartanoic acid A methyl </span><span><span style="font-family:Verdana;">ester (</span><b><span style="font-family:Verdana;">1d</span></b><span style="font-family:Verdana;">), and 3</span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">,21</span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">-diacetoxy-30-nor-(D:A)-friedoolean-20(29)-en-27-oic</span></span><span style="font-family:Verdana;"> acid (</span><b><span style="font-family:Verdana;">5a</span></b><span style="font-family:Verdana;">). Their structures were
文摘在食品加工过程中,美拉德反应虽然对提升食品的风味和品质具有重要作用,但也会衍生一些化学危害物。本文综述了美拉德反应对食品风味和色泽等品质的影响,以及美拉德反应产物的抗氧化和抗突变等特性,同时也探讨了美拉德反应产生的丙烯酰胺(acrylamide,AA)、杂环胺(heterocyclic amines,HAs)和晚期糖基化末端终产物(advanced glycation end products,AGEs)等化学危害物的生成机制、分析和抑制方法。由于3类危害物在食品中的含量较低(ng/g~μg/g)且基质非常复杂,因此其检测均需要采用固相萃取等方法进行分离富集,随后可采用超高效液相色谱串联质谱(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)等方法进行定性定量分析。危害物的抑制主要通过采用更加温和的加工方法、调整工艺参数和添加香辛料及酚类等天然抗氧化物质来实现。
