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Sample records for cationic trypsinogen prss1

  1. The variable phenotype of the p.A16V mutation of cationic trypsinogen (PRSS1) in pancreatitis families

    DEFF Research Database (Denmark)

    Grocock, Christopher J; Rebours, Vinciane; Delhaye, Myriam

    2010-01-01

    Pancreatic Cancer or via a collaborator. DNA samples were tested for mutations in PRSS1, SPINK1, CFTR and CTRC. PATIENTS: Participants were recruited on the basis of either family history of pancreatitis (acute or chronic), or the results of genetic testing. Families were categorised as having Hereditary...

  2. Discrimination of three mutational events that result in a disruption of the R122 primary autolysis site of the human cationic trypsinogen (PRSS1 by denaturing high performance liquid chromatography

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    Férec Claude

    2001-11-01

    Full Text Available Abstract Background R122, the primary autolysis site of the human cationic trypsinogen (PRSS1, constitutes an important "self-destruct" or "fail-safe" defensive mechanism against premature trypsin activation within the pancreas. Disruption of this site by a missense mutation, R122H, was found to cause hereditary pancreatitis. In addition to a c.365G>A (CGC>CAC single nucleotide substitution, a c.365~366GC>AT (CGC>CAT gene conversion event in exon 3 of PRSS1 was also found to result in a R122H mutation. This imposes a serious concern on the genotyping of pancreatitis by a widely used polymerase chain reaction-restriction fragment length polymorphism assay, which could only detect the commonest c.365G>A variant. Materials and methods DNA samples containing either the known c.365G>A or c.365~366GC>AT variant in exon 3 of PRSS1 were used as positive controls to establish a denaturing high performance liquid chromatography (DHPLC assay. Results DHPLC could readily discriminate the two known different mutational events resulting in the R122H mutation. More importantly, under the same experimental conditions, it identified a further mutational event that also occurs in the R122 primary autolysis site but results in a different amino acid substitution: c.364C>T (CGC>TGC; R122C. Conclusions A rapid, simple, and low-cost assay for detecting both the known and new mutations occuring in the R122 primary autolysis site of PRSS1 was established. In addition, the newly found R122C variant represents a likely pancreatitis-predisposing mutation.

  3. Novel mutations of PRSS1 gene in patients with pancreatic cancer among Han population

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    ZENG Kai; LIU Qi-cai; LIN Jian-hua; LIN Xin-hua; ZHUANG Ze-hao; GAO Feng; OU Qi-shui

    2011-01-01

    Background A high mortality rate of pancreatic cancer becomes a bottleneck for further treatment with long-term efficacy. It is urgent to find a new mean to predict the early onset of pancreatic cancer accurately. The authors hypothesized that genetic variants of cationic trypsinogen (PRSS1) gene could affect trypsin expression/function and result in abnormal activation of protease activated receptor-2 (PAR-2), then lead to pancreatic cancer. The aim of this study was to elaborate some novel mutations of PRSS1 gene in the patients with pancreatic cancer.Methods Totally 156 patients with pancreatic cancer and 220 unrelated individuals as controls were enrolled in this study. The mutations of PRSS1 gene were analyzed by direct sequencing. K-ras Mutation Detection Kit was used to find the general k-ras gene disorder in the pancreatic cancer tissue. Then the clinical data were collected and analyzed simultaneously.Results There were two patients who carried novel mutations which was IVS 3 +157 G>C of PRSS1 gene in peripheral blood specimens and pancreatic cancer tissue. What's more, it was surprising to find a novel complicated mutation of exon 3 in PRSS1 gene (c.409 A>G and c.416 C>T) in another young patient. The complicated mutation made No. 135 and No.137 amino acid transfer from Thr to Ala and Thr to Met respectively. No any mutation was found in the normal controls while no mutations of k-ras gene were detected in the three patients.Conclusion Mutations of PRSS1 gene may be an important factor of pancreatic cancer.

  4. A Thai family with hereditary pancreatitis and increased cancer risk due to a mutation in PRSS1 gene

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    Theeraphong Pho-Iam; Wanna Thongnoppakhun; Pa-Thai Yenchitsomanus; Chanin Limwongse

    2005-01-01

    AIM: To investigate mutation of serine protease 1-cationic trypsinogen (CT, PRSS1) gene in members of a Thai family with hereditary pancreatitis and pancreatic cancer.METHODS: Polymerase chain reaction and direct sequencing were performed to analyze the PRSS1 gene in two members of the family affected by pancreatitis.Allele specific amplification (ASA) method was then developed to detect the mutation of the PRSS1 gene in all available members of the family and normal control subjects.RESULTS: A cytosine (C) to thymine (T) mutation at position 2441 (g.2441C>T) of the PRSS1 gene, which results in a substitution of arginine by cysteine at position 116 (R116C) of CT, was identified by direct sequencing in both clinically affected members of the family but was not found in the unaffected member. This mutation, which might be arising from deamination of methylated cytosine in CpG dinucleotide of codon 116 (CGT>FGT), was also detected by the ASA method in the two affected members and a proband's brother but was not observed in unaffected members and 54 normal control subjects.CONCLUSION: Autosomal dominant pancreatitis with increased cancer risk in the studied Thai family is most likely due to missense (R116C) mutation in the PRSS1gene.

  5. Novel mutation and polymorphism of PRSS1 gene in the Chinese patients with hereditary pancreatitis and chronic pancreatitis

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    LIU Qi-cai; GAO Feng; OU Qi-shui; ZHUANG Ze-hao; LIN Shou-rong; YANG Bin; CHENG Zu-jian

    2008-01-01

    Background Mutations in the cationic trypsinogen gene(PRSS1)have been detected in patients with hereditary pancreatitis(HP).This study investigated the prevalence of the R122H(c.365G>A),A121T(c.361 G>A)and D162D (c.488 C>T)mutations or polymorphisms in the common,non-hereditary forms of chronic pancreatitis and in an HP family.Methods DNA was prepared from blood samples of 54 patients with chronic pancreatitis(35 alcoholic,17 idiopathic and 2 hereditary)and 120 normal controls.The PRSS1 genes were amplified by polymerase chain reaction (PCR) and their products were analyzed by sequencing and related clinical data were also collected.Results A new polymorphism(c.488 C>T)of PRSS1 was found in 25 patients with chronic pancreatitis (including one affected member of the H P family)and six members of the normal controls.The C/T genotype was significantly increased in chronic pancreatitis(OR:16.379,95%CI:5.7522-52.3663),the frequency of c.488 C>T change was in according with the Hardy-Weinberg equilibrium,but it doesn't affect the clinical phenotype.The commonly reported change of R122H (c.365G>A)was not detected in any of the study subjects.c.361 G>A was found in 2 affected members and one unaffected carrier in an HP family.One of the affected members of an HP family had c.361 G>A mutation and polymorphism(c.488 C>T)in the PRSS1 gene at the same time.The patient's clinical values(C3,C4,CA19-9 and HbA1c)were higher than those of the other patients with chronic pancreatitis.The two patients with HP developed diabetes mellitus and their father died with pancreatic cancer.Conclusion A new polymorphism(c.488 C>T)in the PRSS1 gene is associated with chronic pancreatitis,but it did not affect the clinical phenotype while the A121T(c.361 G>A)mutation in the gene shows a significant correlation in the patients with H P.

  6. Common genetic variants in the CLDN2 and PRSS1-PRSS2 loci alter risk for alcohol-related and sporadic pancreatitis

    Science.gov (United States)

    Whitcomb, David C.; LaRusch, Jessica; Krasinskas, Alyssa M.; Klei, Lambertus; Smith, Jill P.; Brand, Randall E.; Neoptolemos, John P.; Lerch, Markus M.; Tector, Matt; Sandhu, Bimaljit S.; Guda, Nalini M.; Orlichenko, Lidiya; Alkaade, Samer; Amann, Stephen T.; Anderson, Michelle A.; Baillie, John; Banks, Peter A.; Conwell, Darwin; Coté, Gregory A.; Cotton, Peter B.; DiSario, James; Farrer, Lindsay A.; Forsmark, Chris E.; Johnstone, Marianne; Gardner, Timothy B.; Gelrud, Andres; Greenhalf, William; Haines, Jonathan L.; Hartman, Douglas J.; Hawes, Robert A.; Lawrence, Christopher; Lewis, Michele; Mayerle, Julia; Mayeux, Richard; Melhem, Nadine M.; Money, Mary E.; Muniraj, Thiruvengadam; Papachristou, Georgios I.; Pericak-Vance, Margaret A.; Romagnuolo, Joseph; Schellenberg, Gerard D.; Sherman, Stuart; Simon, Peter; Singh, Vijay K.; Slivka, Adam; Stolz, Donna; Sutton, Robert; Weiss, Frank Ulrich; Wilcox, C. Mel; Zarnescu, Narcis Octavian; Wisniewski, Stephen R.; O'Connell, Michael R.; Kienholz, Michelle L.; Roeder, Kathryn; Barmada, M. Michael; Yadav, Dhiraj; Devlin, Bernie; Albert, Marilyn S.; Albin, Roger L.; Apostolova, Liana G.; Arnold, Steven E.; Baldwin, Clinton T.; Barber, Robert; Barnes, Lisa L.; Beach, Thomas G.; Beecham, Gary W.; Beekly, Duane; Bennett, David A.; Bigio, Eileen H.; Bird, Thomas D.; Blacker, Deborah; Boxer, Adam; Burke, James R.; Buxbaum, Joseph D.; Cairns, Nigel J.; Cantwell, Laura B.; Cao, Chuanhai; Carney, Regina M.; Carroll, Steven L.; Chui, Helena C.; Clark, David G.; Cribbs, David H.; Crocco, Elizabeth A.; Cruchaga, Carlos; DeCarli, Charles; Demirci, F. Yesim; Dick, Malcolm; Dickson, Dennis W.; Duara, Ranjan; Ertekin-Taner, Nilufer; Faber, Kelley M.; Fallon, Kenneth B.; Farlow, Martin R.; Ferris, Steven; Foroud, Tatiana M.; Frosch, Matthew P.; Galasko, Douglas R.; Ganguli, Mary; Gearing, Marla; Geschwind, Daniel H.; Ghetti, Bernardino; Gilbert, John R.; Gilman, Sid; Glass, Jonathan D.; Goate, Alison M.; Graff-Radford, Neill R.; Green, Robert C.; Growdon, John H.; Hakonarson, Hakon; Hamilton-Nelson, Kara L.; Hamilton, Ronald L.; Harrell, Lindy E.; Head, Elizabeth; Honig, Lawrence S.; Hulette, Christine M.; Hyman, Bradley T.; Jicha, Gregory A.; Jin, Lee-Way; Jun, Gyungah; Kamboh, M. Ilyas; Karydas, Anna; Kaye, Jeffrey A.; Kim, Ronald; Koo, Edward H.; Kowall, Neil W.; Kramer, Joel H.; Kramer, Patricia; Kukull, Walter A.; LaFerla, Frank M.; Lah, James J.; Leverenz, James B.; Levey, Allan I.; Li, Ge; Lin, Chiao-Feng; Lieberman, Andrew P.; Lopez, Oscar L.; Lunetta, Kathryn L.; Lyketsos, Constantine G.; Mack, Wendy J.; Marson, Daniel C.; Martin, Eden R.; Martiniuk, Frank; Mash, Deborah C.; Masliah, Eliezer; McKee, Ann C.; Mesulam, Marsel; Miller, Bruce L.; Miller, Carol A.; Miller, Joshua W.; Montine, Thomas J.; Morris, John C.; Murrell, Jill R.; Naj, Adam C.; Olichney, John M.; Parisi, Joseph E.; Peskind, Elaine; Petersen, Ronald C.; Pierce, Aimee; Poon, Wayne W.; Potter, Huntington; Quinn, Joseph F.; Raj, Ashok; Raskind, Murray; Reiman, Eric M.; Reisberg, Barry; Reitz, Christiane; Ringman, John M.; Roberson, Erik D.; Rosen, Howard J.; Rosenberg, Roger N.; Sano, Mary; Saykin, Andrew J.; Schneider, Julie A.; Schneider, Lon S.; Seeley, William W.; Smith, Amanda G.; Sonnen, Joshua A.; Spina, Salvatore; Stern, Robert A.; Tanzi, Rudolph E.; Trojanowski, John Q.; Troncoso, Juan C.; Tsuang, Debby W.; Valladares, Otto; Van Deerlin, Vivianna M.; Van Eldik, Linda J.; Vardarajan, Badri N.; Vinters, Harry V.; Vonsattel, Jean Paul; Wang, Li-San; Weintraub, Sandra; Welsh-Bohmer, Kathleen A.; Williamson, Jennifer; Woltjer, Randall L.; Wright, Clinton B.; Younkin, Steven G.; Yu, Chang-En; Yu, Lei

    2012-01-01

    Pancreatitis is a complex, progressively destructive inflammatory disorder. Alcohol was long thought to be the primary causative agent, but genetic contributions have been of interest since the discovery that rare PRSS1, CFTR, and SPINK1 variants were associated with pancreatitis risk. We now report two significant genome-wide associations identified and replicated at PRSS1-PRSS2 (1×10-12) and x-linked CLDN2 (p < 1×10-21) through a two-stage genome-wide study (Stage 1, 676 cases and 4507 controls; Stage 2, 910 cases and 4170 controls). The PRSS1 variant affects susceptibility by altering expression of the primary trypsinogen gene. The CLDN2 risk allele is associated with atypical localization of claudin-2 in pancreatic acinar cells. The homozygous (or hemizygous male) CLDN2 genotype confers the greatest risk, and its alleles interact with alcohol consumption to amplify risk. These results could partially explain the high frequency of alcohol-related pancreatitis in men – male hemizygous frequency is 0.26, female homozygote is 0.07. PMID:23143602

  7. 胰蛋白酶原基因缺失突变导致早发型自身免疫性相关的多器官多发囊肿的研究%Trypsinogen gene deletion mutation causes early onset autoimmune related pulmonary bulla, hepatic multiple cysts

    Institute of Scientific and Technical Information of China (English)

    徐志峰; 林寿榕; 刘奇才; 陈瑞庆; 林丽清; 翁少煌; 郜峰; 庄则豪; 陈金通

    2014-01-01

    Objective To identification of cationic trypsinogen(PRSS1) gene deletion mutation in au-toimmune related multiple cysts and its pathogenic mechanism. Methods All exons and flanking intron shear region of pancreatitis and polycystic lesions related genes including PRSS1 , cystic fibrosis transmembrane conductance regulator (CFTR), serine protease inhibitor Kazal type 1 (SPINK1), protein kinase D1(PKD1) and PKD2 were analyzed by DNA sequencing technology. The sequential variation of DNA and cDNA were de-tected. Whether the variation associated with disease were detected by comparing with family inside and healthy controls. The mutant expression system was constructed and its functional verification was done. At the same time, immunohistochemical and special staining in patients with lung and liver pancreas biopsy samples were executed. Results In two patients with autoimmune pancreatitis, deletion mutant in exon 2 of PRSS1 gene were first found, and it generating activation peptide deletion trypsinogen with biological activity. The liv-er, lung was lymphocytic and plasma cell infiltration, elastic fibers and reticular fibers decreased the formation of multiple organ polycystic disease. Serum trypsin, elastase and alpha antitrypsin increased significantly. Use of glucocorticoid treatment was effective. Conclusion PRSS1:c.1300_1304 del CCCAG is a new mutation causes early onset of autoimmune pancreatitis and it correlated with multiple organ cyst closely.%目的:探讨由胰蛋白酶原基因(cationic trypsinogen, PRSS1)突变引发的早发型自身免疫性相关的多器官多发囊肿及其致病机制。方法采用DNA全长测序技术分析PRSS1、囊性纤维化跨膜通道调节因子(cystic fibrosis transmembrane conductance regulator, CFTR)、丝氨酸蛋白酶抑制剂 Kazal 1型(serine protease inhibitor Kazal type 1, SPINK1)、蛋白激酶D(protein kinase D, PKD)1和PKD2等胰腺炎和多囊性病变相关基因的所有外显

  8. Urinary trypsinogen-2 dipstick in acute pancreatitis

    DEFF Research Database (Denmark)

    Novovic, Srdan; Ersbøll, Annette Kjaer; Jørgensen, Lars Nannestad

    2010-01-01

    In acute pancreatitis (AP), rapid diagnosis and early treatment are of importance for clinical outcome. Urinary trypsinogen-2 has been suggested as a promising diagnostic marker; however, studies using the urinary trypsinogen-2 dipstick test (UTDT) have provided varying results.......In acute pancreatitis (AP), rapid diagnosis and early treatment are of importance for clinical outcome. Urinary trypsinogen-2 has been suggested as a promising diagnostic marker; however, studies using the urinary trypsinogen-2 dipstick test (UTDT) have provided varying results....

  9. Partially folded intermediates during trypsinogen denaturation

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    Martins N.F.

    1999-01-01

    Full Text Available The equilibrium unfolding of bovine trypsinogen was studied by circular dichroism, differential spectra and size exclusion HPLC. The change in free energy of denaturation was = 6.99 ± 1.40 kcal/mol for guanidine hydrochloride and = 6.37 ± 0.57 kcal/mol for urea. Satisfactory fits of equilibrium unfolding transitions required a three-state model involving an intermediate in addition to the native and unfolded forms. Size exclusion HPLC allowed the detection of an intermediate population of trypsinogen whose Stokes radii varied from 24.1 ± 0.4 Å to 26.0 ± 0.3 Å for 1.5 M and 2.5 M guanidine hydrochloride, respectively. During urea denaturation, the range of Stokes radii varied from 23.9 ± 0.3 Å to 25.7 ± 0.6 Å for 4.0 M and 6.0 M urea, respectively. Maximal intrinsic fluorescence was observed at about 3.8 M urea with 8-aniline-1-naphthalene sulfonate (ANS binding. These experimental data indicate that the unfolding of bovine trypsinogen is not a simple transition and suggest that the equilibrium intermediate population comprises one intermediate that may be characterized as a molten globule. To obtain further insight by studying intermediates representing different stages of unfolding, we hope to gain a better understanding of the complex interrelations between protein conformation and energetics.

  10. Porphyrin Induced Laser Deactivation of Trypsinogen-Trypsin Conversion

    Science.gov (United States)

    Perido, Joanna; Brancaleon, Lorenzo

    2015-03-01

    Pancreatitis is caused by the inflammation of the pancreas, where the digestive enzyme trypsin is activated from the precursor enzyme trypsinogen while still in the pancreas. The presence of trypsin in the pancreas causes auto-activation of trypsinogen, resulting in greater inflammation and auto-digestion of the pancreas. In severe cases, this cascade effect can lead to organ failure, diabetes, and pancreatic cancer. Our hypothesis is that if trypsinogen is prevented from auto-activating into trypsin, then this cascade can be stopped. We propose to do this by inducing conformational changes in trypsinogen when bound to a photoactive porphyrin dye. Porphyrins are comprised of four linked heterocyclic groups forming a flat ring, and bind well with proteins such as trypsinogen. In this study we used spectroscopic techniques to probe the binding of meso-tetrakis (4-sulfonatephenyl) porphyrin (TSPP) to trypsinogen in vitro, as a preliminary step to then prompt and characterize conformational changes of trypsinogen through irradiation. If conformational changes are detected the trypsinogen will be tested for trypsin inactivation. This investigation may provide promising initial results to the possible use of porphyrins as an inhibitor of the self-activation of trypsinogen into trypsin, and a potential inhibitor of pancreatitis. MARC*U-STAR.

  11. The relation of cationic trypsinogen gene G191R mutation and pathogenesis of pancreatitis%阴离子型胰蛋白酶原基因G191R突变与胰腺炎发病的关系

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    李璐; 丁辉; 杨玉秀; 韩双印; 王春荣

    2014-01-01

    目的 分析阴离子型胰蛋白酶原(PRSS2)基因G191R突变在急性胰腺炎(AP)和慢性胰腺炎(CP)患者中的发生率,探讨PRSS2基因突变对胰腺炎易感性的影响.方法 采集82例AP、73例CP及138例健康体检者的血液标本,提取基因组DNA.应用巢式PCR对PRSS2基因进行扩增.PCR产物用Hpy188Ⅲ酶切,行限制性片段长度多态性分析(RFLP),部分产物测序验证.结果 PRSS2基因的巢式PCP产物长度为436 bp,RFLP2获得309 bp和127 bp两个片段,为RPSS2基因G191R突变(即GGA→AGA)所致.DNA测序证实PRSS2基因G191R突变.AP患者中5例发生RPSS2基因G191R突变,突变率为6.1%(5/82),OR=0.682,95% CI 0.231 ~ 2.010; CP患者突变率为1.4% (1/73),OR =0.145,95% CI 0.019~1.145;健康对照组为8.7% (12/138).CP组的G191R突变率显著低于健康对照组(x2 =0.432,P=0.035),而AP组与健康对照组的差异无统计学意义(x2=0.487,P=0.485).结论 PRSS2基因G191R突变可促进阴离子型胰蛋白酶原的降解,降低慢性胰腺炎的发生率.%Objective To observe the prevalence of anionic trypsinogen (PRSS2) gene G191R mutation in patients with acute pancreatitis (AP) and chronic pancreatitis (CP),and to investigate the effect of PRSS2 gene G191R mutation on susceptibility to pancreatitis.Methods The blood samples of 82 patients with acute pancreatitis,73 patients with chronic pancreatitis and 138 healthy subjects were collected,and genomic DNA was extracted.Nest PCR were performed to amplify PRSS2 gene and restriction fragment length polymorphism (RFLP) was followed by using Hpy188Ⅲ to distinguish the G191R mutation.DNA sequencing analysis was performed to confirm the mutation status.Results The size of nest PCR products was 436 bp.RFLP2 produced 309 bp and 127 bp fragments,which were resulted from PRSS2 gene G191R mutation (GGA →AGA).DNA sequencing analysis of the PCR products further confirmed the PRSS2 gene G191R mutation.Five of eighty-two(6.1%) patients with acute

  12. Intragenic duplication: a novel mutational mechanism in hereditary pancreatitis

    DEFF Research Database (Denmark)

    Joergensen, Maiken T; Geisz, Andrea; Brusgaard, Klaus

    2011-01-01

    In a hereditary pancreatitis family from Denmark, we identified a novel intragenic duplication of 9 nucleotides in exon-2 of the human cationic trypsinogen (PRSS1) gene (c.63_71dup) which at the amino-acid level resulted in the insertion of 3 amino acids within the activation peptide of cationic...

  13. Molecular characterization of trypsinogens and development of trypsinogen gene expression and tryptic activities in grass carp (Ctenopharyngodon idellus) and topmouth culter (Culter alburnus).

    Science.gov (United States)

    Ruan, Guo-Liang; Li, Yang; Gao, Ze-Xia; Wang, Huan-Ling; Wang, Wei-Min

    2010-01-01

    This study examined the gene structures and expression of trypsinogens, as well as the trypsin activities of the grass carp Ctenopharyngodon idellus (herbivorous) and the topmouth culter Culter alburnus (carnivorous), which are commercially important freshwater species of the family Cyprinidae in China. Isolated full-length trypsinogen cDNA clones were 869 bp and 857 bp. The deduced amino acid sequences were 242aa and 247aa long, both containing the highly conserved residues essential for serine protease catalytic and conformational maintenance. The results from isoelectric and phylogenetic analyses suggest that grass carp trypsinogen is grouped with teleost trypsinogen group I, while topmouth culter trypsinogen is grouped with group II. The expression pattern of trypsinogen mRNA was similar between these two species, appearing 2 days post-hatching (dph) and reaching peaks at 11 and 23 dph. The trypsin-specific activities in both species were detected 2 dph and reached the major peaks at 8 dph, however the minor peaks were observed at 20 dph in the grass carp and 17 dph in the topmouth culter. The trypsin-specific activity was significantly higher in the grass carp than in the topmouth culter, which may be attributed to the nature of their different nutritional habits.

  14. Trypsinogen activation in acute and chronic pancreatitis: Is it a prerequisite?

    OpenAIRE

    Sah, Raghuwansh P.; Saluja, Ashok K.

    2011-01-01

    Trypsinogen activation is sufficient to induce acute pancreatitis in an experimental model. However, whether it is a requirement for the pathogenesis of acute and chronic pancreatitis remains to be explored.

  15. Clinical value of rapid urine trypsinogen-2 test strip, urinary trypsinogen activation peptide, and serum and urinary activation peptide of carboxypeptidase B in acute pancreatitis

    Institute of Scientific and Technical Information of China (English)

    Jesús Sáez; Juan Martínez; Celia Trigo; José Sánchez-Payá; Luis Compa(n)y; Raquel Laveda; Pilar Gri(n)ó; Cristina García; Miguel Pérez-Mateo

    2005-01-01

    AIM: To assess the usefulness of urinary trypsinogen-2 test strip, urinary trypsinogen activation peptide (TAP),and serum and urine concentrations of the activation peptide of carboxypeptidase B (CAPAP) in the diagnosisof acute pancreatitis.METHODS: Patients with acute abdominal pain and hospitalized within 24 h after the onset of symptoms were prospectively studied. Urinary trypsinogen-2 was considered positive when a clear blue line was observed (detection limit 50 μg/L). Urinary TAP was measured using a quantitative solid-phase ELISA, and serum and urinary CAPAP by a radioimmunoassay method.RESULTS: Acute abdominal pain was due to acute pancreatitis in 50 patients and turned out to be extrapancreatic in origin in 22 patients. Patients with acute pancreatitis showed significantly higher median levels of serum and urinary CAPAP levels, as well as amylase and lipase than extrapancreatic controls. Median TAP levels were similar in both groups. The urinary trypsinogen-2 test strip was positive in 68% of patients with acute pancreatitis and 13.6% in extrapancreatic controls (P<0.01). Urinary CAPAP was the most reliable test for the diagnosis of acute pancreatitis (sensitivity 66.7%, specificity 95.5%, positive and negative predictive values 96.6% and 56.7%, respectively), with a 14.6 positive likelihood ratio for a cut-off value of 2.32 nmol/L.CONCLUSION: In patients with acute abdominal pain,hospitalized within 24 h of symptom onset, CAPAP in serum and urine was a reliable diagnostic marker of acute pancreatitis. Urinary trypsinogen-2 test strip showed a clinical value similar to amylase and lipase.Urinary TAP was not a useful screening test for the diagnosis of acute pancreatitis.

  16. Genetics of acute and chronic pancreatitis: An update

    OpenAIRE

    Ravi Kanth, VV; Nageshwar Reddy, D

    2014-01-01

    Progress made in identifying the genetic susceptibility underlying acute and chronic pancreatitis has benefitted the clinicians in understanding the pathogenesis of the disease in a better way. The identification of mutations in cationic trypsinogen gene (PRSS1 gene; functional gain mutations) and serine protease inhibitor kazal type 1 (SPINK1 gene; functional loss mutations) and other potential susceptibility factors in genes that play an important role in the pancreatic secretory functions ...

  17. Intragenic Duplication A Novel Mutational Mechanism in Hereditary Pancreatitis

    DEFF Research Database (Denmark)

    Joergensen, M. T.; Geisz, A.; Brusgaard, K.

    2011-01-01

    OBJECTIVES: In a hereditary pancreatitis family from Denmark, we identified a novel intragenic duplication of 9 nucleotides in exon-2 of the human cationic trypsinogen (PRSS1) gene (c.63_71dup) which at the amino-acid level resulted in the insertion of 3 amino acids within the activation peptide...... pancreatitis. The accelerated activation of p.K23_I24insIDK by cathepsin B is a unique biochemical property not found in any other pancreatitis-associated trypsinogen mutant. In contrast, the robust autoactivation of the novel mutant confirms the notion that increased autoactivation is a disease......-relevant mechanism in hereditary pancreatitis....

  18. Trypsinogen-like cDNAs and quantitative analysis of mRNA levels from the Indianmeal moth, Plodia interpunctella.

    Science.gov (United States)

    Zhu, Y C; Kramer, K J; Dowdy, A K; Baker, J E

    2000-11-01

    Two cDNA fragments encoding full-length trypsinogen-like proteins were cloned from larvae of two strains (RC688s and HD198r) of the Indianmeal moth, Plodia interpunctella (Hübner), which differed in their sensitivity to Bacillus thuringiensis protoxins. One cDNA fragment contained 874 nucleotides, including a 780-nucleotide open reading frame that encoded a trypsinogen-like protein (PiT2b). Another cDNA fragment amplified from both P. interpunctella strains contained 864 nucleotides including a 780 bp open reading frame encoding a second trypsinogen-like protein (PiT2c). The cDNA sequence of PiT2b shared 89% sequence identity with PiT2a, a trypsinogen-like protein cloned previously from this species. The cDNA sequences of PiT2a and PiT2c shared 83% identity. The cDNA sequence identity between PiT2b and PiT2c was 80%. The cDNA for PiT2b from strain RC688s was different at six nucleotide positions from that of PiT2b from strain HD198r. Five nucleotide replacements occurred in the open reading frame leading to amino acid changes at all five positions. There were five nucleotide differences in the cDNAs for PiT2c trypsinogen-like proteins from the two strains. Two nucleotide substitutions in the open reading frame resulted in replacements of two amino acid residues in the deduced protein sequences. Amino acid sequences for PiT2a and PiT2b shared 84% identity, but only 50% identity was observed between PiT2c and the other two trypsinogen-like proteins. The deduced amino acid sequences for PiT2b and PiT2c included both signal and zymogen activation peptides and amino acid sequence motifs which are conserved in seven homologous trypsinogen-like proteins from other insects. Typical features of the putative trypsinogen-like proteins from P. interpunctella included the serine proteinase active site triad (His(81), Asp(133), and Ser(233)), three pairs of cysteine residues for disulfide bridges, and three residues, Asp(227), Gly(250), and Gly(260), that help to confer trypsin

  19. Trypsinogen test

    Science.gov (United States)

    ... is broken) Considerations Other tests used to detect pancreas diseases may include: Serum amylase Serum lipase Alternative Names ... Related MedlinePlus Health Topics Cystic Fibrosis Pancreatic Cancer Pancreatic Diseases Browse the Encyclopedia A.D.A.M., Inc. ...

  20. Molecular characterization of two trypsinogens in the orange-spotted grouper, Epinephelus coioides, and their expression in tissues during early development.

    Science.gov (United States)

    Liu, Chun-Hung; Chen, Ya-Huei; Shiu, Ya-Li

    2013-04-01

    In this study, we cloned two trypsinogens of the orange-spotted grouper, Epinephelus coioides, and analyzed their structure, expression, and activity. Full-length trypsinogen complementary (c)DNAs, named T1 and T2, were 900 and 875 nucleotides, and translated 242 and 244 deduced amino acid peptides, respectively. Both trypsinogens contained highly conserved residues essential for serine protease catalytic and conformational maintenance. Results from isoelectric and phylogenetic analyses suggested that both trypsinogens were grouped into trypsinogen group I. Both trypsinogens had similar expression patterns of negative relationship with body weight; expression was first detected at 1 day post-hatching (DPH) and exhibited steady-state expression during early development at 1-25 DPH. Both expression and activity levels significantly increased after 30 DPH due to metamorphosis. Grouper larval development is very slow with insignificant changes in total length and body weight before 8 DPH. The contribution of live food to an increase in the trypsin activity profile may explain their importance in food digestion and survival of larvae during early larval development.

  1. Relationship between Carbachol Hyperstimulation-induced Pancreatic Intracelluar Trypsinogen and NF-кB Activation in Rats in vitro

    Institute of Scientific and Technical Information of China (English)

    Chunfang JIANG; Hai ZHENG; Sunan LIU; Kaifeng FANG

    2008-01-01

    The relationship between intracelluar trypsinogen activation and NF-r,B activation in rat pancreatic acinar cells induced by M3 cholinergic receptor agonist (carbachoi) hyperstimulation was studied. Rat pancreatic acinar cells were isolated, cultured and treated with carbachol, the active pro- tease inhibitor (pefabloc) and NF-кB inhibitor (PDTC) in vitro. Intracelluar trypsin activity was measured by using a fluorogenie substrate. The activity of NF-кB was monitored by using electro- phoretic mobility shift assay. The results showed that after pretreatment with 2 mmol/L pefabloc, the activities of trypsin and NF-кB in pancreatic acinar cells treated with high concertrations of carbachol (10-3 mol/L) in vitro was significantly decreased as compared with control group (P<0.01). The addi- tion of 10-2mol/L PDTC resulted in a significant decrease of NF-кB activities in pancreatic acinar cells after treated with high concertrations of carbachol (10-3 mol/L) in vitro, but the intracelluar trypsinogen activity was not obviously inhibited (P>0.05). It was concluded that intracelluar trypsi- nogen activation is likely involved in the regulation of high concertrations of carbachol-induced NF-кB activation in pancreatic acinar cells in vitro. NF-кB activation is likely not necessary for high concertrations of carbachol-induced trypsinogen activation in pancreatic acinar cells in vitro.

  2. TO EVALUATE THE EFFICACY OF URINARY TRYPSINOGEN 2 DIPSTICK TEST IN DIAGNOSING ACUTE PANCREATITIS

    Directory of Open Access Journals (Sweden)

    Prem Anandh

    2016-08-01

    Full Text Available BACKGROUND Pancreatitis is a common cause of abdominal pain in the emergency room. Serum amylase and lipase are the initial screening investigations. A rapid urine analysis by a dipstick to detect urinary trypsinogen is a good screening test. MATERIALS AND METHODOLOGY This study was conducted after obtaining the Institutional Ethics Committee (IEC clearance, Reference No.: CSP - MED/14/FEB12/50. Informed consent was obtained from all study participants and ICH/GCP guidelines were followed. The present prospective study was done during the period of June 2013 to October 2015, which involved a group of 98 patients with upper abdominal pain (Reporting within 36 hours of onset of pain who came to the Department of Surgery of Sri Ramachandra Medical College and Research Institute. RESULTS A total of 98 consecutive patients with upper abdominal pain who fulfilled the inclusion criteria and exclusion criteria were enrolled in the study during the period of June 2013 - October 2015. When we analysed the patients with upper abdominal pain we found that in the age group 21-30, there were 22 patients (22.9%; in 31-40 years, there were 28 patients (29.2%; in 41-50 years, there were 17 patients (17.7%; in 51-60 years, there were 18 patients (18.8%; and in between 61-70 years, there were 11 patients (11.5% of study group (1, 2. CONCLUSIONS The analysis of the demographics of our study showed that 40.8% of acute upper abdominal pains were due to acute pancreatitis and 59.2% were non-pancreatic in origin. Male Patients accounted for 75.0% and 65.5% respectively in the acute pancreatitis and non-pancreatic groups. In both acute pancreatitis and non-pancreatic groups, major clustering of patients was seen in the age group of 31-40 yrs.

  3. Urinary trypsinogen-2 for diagnosing acute pancreatitis:a meta-analysis

    Institute of Scientific and Technical Information of China (English)

    Tao Jin; Wei Huang; Kun Jiang; Jun-Jie Xiong; Ping Xue; Muhammad A Javed; Xiao-Nan Yang and Qing Xia

    2013-01-01

    BACKGROUND: Currently, serum amylase and lipase are the most popular laboratory markers for early diagnosis of acute pancreatitis with reasonable sensitivity and specificity. Urinary trypsinogen-2 (UT-2) has been increasingly used but its clinical value for the diagnosis of acute pancreatitis and post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis has not yet been systematically assessed. DATA SOURCES: A comprehensive search was carried out using PubMed (MEDLINE), Embase, and Web of Science for clinical trials,  which  studied  the  usefulness  of  UT-2  as  a  diagnostic marker  for  acute  pancreatitis.  Sensitivity,  specificity  and  the diagnostic odds ratios (DORs) with 95% confidence interval (CI) were calculated for each study and were compared with serum amylase  and  lipase.  Summary  receiver-operating  curves  were conducted and the area under the curve (AUC) was evaluated. RESULTS: A  total  of  18  studies  were  included.  The  pooled sensitivity  and  specificity  of  UT-2  for  the  diagnosis  of  acute pancreatitis  were  80%  and  92%,  respectively  (AUC=0.96, DOR=65.63,  95%  CI:  31.65-139.09).  The  diagnostic  value of  UT-2  was  comparable  to  serum  amylase  but  was  weaker than  serum  lipase.  The  pooled  sensitivity  and  specificity  for the  diagnosis  of  post-ERCP  pancreatitis  were  86%  and  94%, respectively (AUC=0.92, DOR=77.68, 95% CI: 24.99-241.48). CONCLUSIONS: UT-2 as a rapid test could be potentially used for  the  diagnosis  of  post-ERCP  pancreatitis  and  to  an  extent

  4. Sweat chloride and immunoreactive trypsinogen in infants carrying two CFTR mutations and not affected by cystic fibrosis.

    Science.gov (United States)

    Castellani, Carlo; Tridello, Gloria; Tamanini, Anna; Assael, Baroukh M

    2016-01-11

    Newborns with raised immunotrypsinogen levels who have non-pathological sweat chloride values and carry two cystic fibrosis transmembrane regulator (CFTR) mutations of which at least one is not acknowledged to be cystic fibrosis (CF)-causing are at risk of developing clinical manifestations consistent with CFTR-related disorders or even CF. It is not known whether newborns with similar genotypes and normal immunoreactive trypsinogen (IRT) may share the same risk. This study found that newborns with these characteristics and normal IRT have lower sweat chloride values than those with raised IRT (p=0.007).

  5. Clinical value of serum amylase, serum trypsinogen-2, IL-10 and platelet activating factor detection in diagnosis of post-ERCP pancreatitis

    Institute of Scientific and Technical Information of China (English)

    Di Wang; Xue-Song Li; Peng-Peng Cai

    2016-01-01

    Objective:To explore the clinical value of serum amylase, serum trypsinogen-2, IL-10 and platelet activating factor detection in the diagnosis of post-ERCP pancreatitis.Methods:A total of 256 patients with ERCP were selected in our hospital of the digestive department of internal medicine from January 2015 to December 2015. According to different symptoms, signs, serum amylase and pancreatic CT examination results after ERCP, the subjects were divided into three groups: control group, hyperlipidemia group and PEP group. Serum trypsinogen-2, IL-10, platelet activating factor were detected.Results:There were statistically significant differences in serum trypsinogen-2, IL-10, platelet activating factor among control group, hyperlipidemia group and PEP group patients with serum amylase (Fgroup = 269.578, 139.492, 145.637, 126.891, allP = 0.000), and the value of PEP group was the highest. There were statistically significant differences in serum trypsinogen-2, IL-10, platelet activating factor at different time point (Ftime = 602.506, 494.375, 462.512, 239.564, allP = 0.000), the serum amylase level in the patients with hyperlipidemia group reached the highest value after 4 h, but the 24 h was lower than the normal level after operation, the serum amylase in PEP group increased rapidly after 4 h, and the 24 h was still increased after operation; The serum trypsinogen-2, IL-10, platelet activating factor were all highest 4 h after the operation in the hyperlipidemia group and PEP group, and the 24 h after the operation were all decreased. In PEP group, serum amylase, serum trypsinogen-2, IL-10, platelet activating factor 4 h after the operation and 24 h after the operation were significantly higher than those before operation (Finteractive = 28.492, 22.614, 16.573, 7.819, allP = 0.000). In PEP group, the serum amylase had positive correlations with serum trypsinogen-2, IL-10, platelet activating factor (r=0.591, 0.662, 0.681, allP<0.05).Conclusions: Serum amylase

  6. Genetics of acute and chronic pancreatitis: An update.

    Science.gov (United States)

    Ravi Kanth, Vv; Nageshwar Reddy, D

    2014-11-15

    Progress made in identifying the genetic susceptibility underlying acute and chronic pancreatitis has benefitted the clinicians in understanding the pathogenesis of the disease in a better way. The identification of mutations in cationic trypsinogen gene (PRSS1 gene; functional gain mutations) and serine protease inhibitor kazal type 1 (SPINK1 gene; functional loss mutations) and other potential susceptibility factors in genes that play an important role in the pancreatic secretory functions or response to inflammation during pancreatic injury has changed the current concepts and understanding of a complex multifactorial disease like pancreatitis. An individual's susceptibility to the disease is governed by genetic factors in combination with environmental factors. Candidate gene and genetic linkage studies have identified polymorphisms in cationic trypsinogen (PRSS1), SPINK1, cystic fibrosis trans-membrane conductance regulator (CFTR), Chymotrypsinogen C (CTRC), Cathepsin B (CTSB) and calcium sensing receptor (CASR). Individuals with polymorphisms in the mentioned genes and other as yet identified genes are at an enhanced risk for the disease. Recently, polymorphisms in genes other than those involved in "intra-pancreatic trypsin regulatory mechanism" namely Claudin-2 (CLDN2) and Carboxypeptidase A1 (CPA1) gene have also been identified for their association with pancreatitis. With ever growing number of studies trying to identify the genetic susceptibility in the form of single nucleotide polymorphisms, this review is an attempt to compile the available information on the topic.

  7. Genetics of acute and chronic pancreatitis: An update

    Institute of Scientific and Technical Information of China (English)

    VV; Ravi; Kanth; D; Nageshwar; Reddy

    2014-01-01

    Progress made in identifying the genetic susceptibility underlying acute and chronic pancreatitis has benefitted the clinicians in understanding the pathogenesis of the disease in a better way. The identification of mutations in cationic trypsinogen gene(PRSS1 gene; functional gain mutations) and serine protease inhibitor kazal type 1(SPINK1 gene; functional loss mutations) and other potential susceptibility factors in genes that play an important role in the pancreatic secretory functions or response to inflammation during pancreatic injury has changed the current concepts and understanding of a complex multifactorial disease like pancreatitis. An indi-vidual’s susceptibility to the disease is governed by ge-netic factors in combination with environmental factors. Candidate gene and genetic linkage studies have iden-tified polymorphisms in cationic trypsinogen(PRSS1), SPINK1, cystic fibrosis trans-membrane conductance regulator(CFTR), Chymotrypsinogen C(CTRC), Ca-thepsin B(CTSB) and calcium sensing receptor(CASR). Individuals with polymorphisms in the mentioned genes and other as yet identified genes are at an enhanced risk for the disease. Recently, polymorphisms in genes other than those involved in "intra-pancreatic trypsin regulatory mechanism" namely Claudin-2(CLDN2) andCarboxypeptidase A1(CPA1) gene have also been iden-tified for their association with pancreatitis. With ever growing number of studies trying to identify the genetic susceptibility in the form of single nucleotide polymor-phisms, this review is an attempt to compile the avail-able information on the topic.

  8. cDNA sequence, mRNA expression and genomic DNA of trypsinogen from the indianmeal moth, Plodia interpunctella.

    Science.gov (United States)

    Zhu, Y C; Oppert, B; Kramer, K J; McGaughey, W H; Dowdy, A K

    2000-02-01

    Trypsin-like enzymes are major insect gut enzymes that digest dietary proteins and proteolytically activate insecticidal proteins produced by the bacterium Bacillus thuringiensis (Bt). Resistance to Bt in a strain of the Indianmeal moth, Plodia interpunctella, was linked to the absence of a major trypsin-like proteinase (Oppert et al., 1997). In this study, trypsin-like proteinases, cDNA sequences, mRNA expression levels and genomic DNAs from Bt-susceptible and -resistant strains of the Indianmeal moth were compared. Proteinase activity blots of gut extracts indicated that the susceptible strain had two major trypsin-like proteinases, whereas the resistant strain had only one. Several trypsinogen-like cDNA clones were isolated and sequenced from cDNA libraries of both strains using a probe deduced from a conserved sequence for a serine proteinase active site. cDNAs of 852 nucleotides from the susceptible strain and 848 nucleotides from the resistant strain contained an open reading frame of 783 nucleotides which encoded a 261-amino acid trypsinogen-like protein. There was a single silent nucleotide difference between the two cDNAs in the open reading frame and the predicted amino acid sequence from the cDNA clones was most similar to sequences of trypsin-like proteinases from the spruce budworm, Choristoneura fumiferana, and the tobacco hornworm, Manduca sexta. The encoded protein included amino acid sequence motifs of serine proteinase active sites, conserved cysteine residues, and both zymogen activation and signal peptides. Northern blotting analysis showed no major difference between the two strains in mRNA expression in fourth-instar larvae, indicating that transcription was similar in the strains. Southern blotting analysis revealed that the restriction sites for the trypsinogen genes from the susceptible and resistant strains were different. Based on an enzyme size comparison, the cDNA isolated in this study corresponded to the gene for the smaller of two

  9. Development of a rapid high-efficiency scalable process for acetylated Sus scrofa cationic trypsin production from Escherichia coli inclusion bodies.

    Science.gov (United States)

    Zhao, Mingzhi; Wu, Feilin; Xu, Ping

    2015-12-01

    Trypsin is one of the most important enzymatic tools in proteomics and biopharmaceutical studies. Here, we describe the complete recombinant expression and purification from a trypsinogen expression vector construct. The Sus scrofa cationic trypsin gene with a propeptide sequence was optimized according to Escherichia coli codon-usage bias and chemically synthesized. The gene was inserted into pET-11c plasmid to yield an expression vector. Using high-density E. coli fed-batch fermentation, trypsinogen was expressed in inclusion bodies at 1.47 g/L. The inclusion body was refolded with a high yield of 36%. The purified trypsinogen was then activated to produce trypsin. To address stability problems, the trypsin thus produced was acetylated. The final product was generated upon gel filtration. The final yield of acetylated trypsin was 182 mg/L from a 5-L fermenter. Our acetylated trypsin product demonstrated higher BAEE activity (30,100 BAEE unit/mg) than a commercial product (9500 BAEE unit/mg, Promega). It also demonstrated resistance to autolysis. This is the first report of production of acetylated recombinant trypsin that is stable and suitable for scale-up.

  10. Relationship between Carbachol Hyperstimulation-Induced Pancreatic Acinar Cellular Injury and Trypsinogen or NF-κB Activation in Rats in vitro

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The relationship between M3 cholinergic receptor agonist (carbachol) hyperstimulationinduced pancreatic acinar cellular injury and trypsinogen activation or NF-κB activation in rats was studied in vitro. Rat pancreatic acinar cells were isolated, cultured and treated with carbachol, the active protease inhibitor (pefabloc), and NF-κB inhibitor (PDTC) in vitro. Intracellular trypsin activity was measured by using a fluorogenic substrate. The cellular injury was evaluated by measuring the leakage of LDH from pancreatic acinar cells. The results showed that as compared with control group, 10-3 mol/L carbachol induced a significant increase of the intracellular trypsin activity and the leakage of LDH from pancreatic acinar cells. Pretreatment with 2 mmol/L pefabloc could significantly decrease the activity of trypsin and the leakage of LDH from pancreatic acinar cells (P <0.01) following the treatment with a high concentration of carbachol (10-3 mol/L) in vitro. The addition of 10-2 mol/L PDTC didn't result in a significant decrease in the activity of trypsin and the leakage of LDH from pancreatic acinar cells treated with a high concentration of carbachol (10-3 mol/L) in vitro (P>0.05). It was concluded that intracellular trypsinogen activation is likely involved in pancreatic acinar cellular injury induced by carbachol hyperstimulation in vitro. NF-κB activation may not be involved in pancreatic acinar cellular injury induced by carbachol hyperstimulation in vitro.

  11. Pancreatic cancer risk in hereditary pancreatitis

    Directory of Open Access Journals (Sweden)

    Frank Ulrich Weiss

    2014-02-01

    Full Text Available Inflammation is part of the body’s immune response in order to remove harmful stimuli – like pathogens, irritants or damaged cells - and start the healing process. Recurrent or chronic inflammation on the other side seems a predisposing factor for carcinogenesis and has been found associated with cancer development. In chronic pancreatitis mutations of the cationic trypsinogen (PRSS1 gene have been identified as risk factors of the disease. Hereditary pancreatitis is a rare cause of chronic pancreatic inflammation with an early onset, mostly during childhood. Hereditary pancreatitis often starts with recurrent episodes of acute pancreatitis and the clinical phenotype is not very much different from other etiologies of the disease. The long-lasting inflammation however generates a tumor promoting environment and represents a major risk factor for tumor development This review will reflect our knowledge concerning the specific risk of hereditary pancreatitis patients to develop pancreatic cancer.

  12. Two cases of chronic pancreatitis associated with anomalous pancreaticobiliary ductal union and SPINK1 mutation

    Directory of Open Access Journals (Sweden)

    Eun Sam Rho

    2013-05-01

    Full Text Available Chronic pancreatitis is a progressive inflammatory disease resulting from repeated episodes of acute pancreatitis that impair exocrine function and eventually produce endocrine insufficiency. Some causes of chronic pancreatitis appear to be associated with alterations in the serine&#8211;protease inhibitor, Kazal type 1 (SPINK1 , cationic trypsinogen (PRSS1 , and cystic fibrosis&#8211;transmembrane conductance regulator (CFTR genes, or with structural disorders in the pancreaticobiliary ductal system, such as pancreatic divisum or anomalous pancreaticobiliary ductal union (APBDU. However, it is unusual to observe both genetic alteration and structural anomaly. Here, we report 2 cases with both APBDU and a mutation in the SPINK1 genes, and we discuss the implications of these findings in clinical practice.

  13. Role of genetic disorders in acute recurrent pancreatitis

    Institute of Scientific and Technical Information of China (English)

    Volker Keim

    2008-01-01

    There was remarkable progress in the understanding of the role genetic risk factors in chronic pancreatitis.These factors seem to be much more important than thought in the past.The rare autosomal-dominant mutations N29I and R122H of PRSS1(cationic trypsinogen) as well as the variant N34S of SPINK1(pancreatic secretory trypsin inhibitor) are associated to a disease onset in childhood or youth.Compared to chronic alcoholic pancreatitis the progression is slow so that for a long time only signs of acute-recurrent pancreatitis are found.Only at later time points(more than 10-15 years) there is evidence for chronic pancreatitis in the majority of patients.Acute recurrent pancreatitis may therefore be regarded as a transition state until definite signs of chronic pancreatitis are detectable.

  14. Genetic, epidemiological, and clinical aspects of hereditary pancreatitis: a population-based cohort study in Denmark

    DEFF Research Database (Denmark)

    Brusgaard, Klaus

    2010-01-01

    regulator gene (CFTR) and serine protease inhibitor Kazal type 1 gene (SPINK1) mutations with patients who retained the diagnosis of true idiopathic pancreatitis (tIP) after genetic testing for HP, SPINK1, and CFTR mutations. METHODS: Patients with PUO were identified in the Danish National Registry...... of Patients or were referred by clinicians. DNA from blood was analyzed for cationic trypsinogen (PRSS1), SPINK1, and CFTR mutations. Considering the diagnosis of HP, a pedigree was drawn for each patient. RESULTS: A genetic mutation was found in 40% of 122 patients with PUO. After testing first......-degree relatives of the 18 initially identified HP patients, 38 HP patients in total were identified, and 28 patients had SPINK1-CFTR mutations. Among HP patients, no p.N29I mutations were found and the p.A16V mutation was more frequent than previously reported, 45 and 32% had exocrine and endocrine insufficiency...

  15. Motion-Genetic Testing is Useful in the Diagnosis of Nonhereditary Pancreatic Conditions: Arguments for the Motion

    Directory of Open Access Journals (Sweden)

    David C Whitcomb

    2003-01-01

    Full Text Available Mutations of three major genes are associated with an increased risk of acute and chronic pancreatitis: the cationic trypsinogen (PRSS1 gene, the cystic fibrosis transmembrane conductance regulator (CFTR gene, and the pancreatic secretory trypsin inhibitor (PSTI or serine protease inhibitor, Kazal type 1 (SPINK1 gene. Some autosomal dominant forms of hereditary pancreatitis are associated with mutations of the PRSS1 gene, which can be readily identified by genetic testing. Mutations of the CFTR gene can lead either to cystic fibrosis or to idiopathic chronic pancreatitis, and to a variety of cystic fibrosis-associated disorders, including congenital bilateral absence of the vas deferens and sinusitis. These mutations, as with those of the SPINK1 (or PSTI gene, are prevalent in North America; thus, the presence of such a mutation in an asymptomatic person does not confer a high risk of developing pancreatitis. Combinations of mutations of the PRSS1 and SPINK1 genes lead to more severe disease, as indicated by an earlier onset of symptoms, which suggests that SPINK1 is a disease modifier. The major fear expressed by potential candidates for genetic testing is that the results could lead to insurance discrimination. Studies of the positive predictive value of genetic tests are hampered by recruitment bias and lack of knowledge of family history of pancreatitis. Genetic testing is most useful for persons for whom family members have already been found to exhibit a particular pancreatitis-associated mutation. In the future, increased knowledge of the myriad genetic causes of pancreatitis, as well as advances in the diagnosis and treatment of early chronic pancreatitis, should enhance the utility of genetic testing.

  16. 胰蛋白酶原-2检测对急性胰腺炎的诊断价值%Comparative analysis among trypsinogen-Ⅱ p-amylase and α-amylase for the diagnosis of acute pancreatitis

    Institute of Scientific and Technical Information of China (English)

    张凤花

    2010-01-01

    Objective To discuss the clinic at diagnosis value of trypsinogen-Ⅰ in acute pancreatltis(AP) by the means of comparative analysis among trypsinogen-Ⅱ.p-amylase,and uroamylase.Methods Trypsinogen-1 by immunostratographie analysis,p-Amylase by immuno-suppression and a-Amylase by enzyme coupling reaction.In 69 samples with pancreatitis were measured.Results Trypsinogen-Ⅱ in 65 samplest p-Amylase in 63 samples and Amylase in 59 samples were positive.The diagnositic sensitivity of trypsinogen-Ⅱ,p-Amylase,Amylase were 94.2%,91.3% and 85.5%,respectively The diagnositic specificity were 90.3%,87.1% and 74.2% respectively.Conclusion Trypsinogen-Ⅱ is better index for the detection of acute panereatitis.%目的 探讨胰蛋白酶原-2检测对急性胰腺炎的诊断价值.方法 采用免疫层析法测定69例急性胰腺炎(AP)患者尿胰蛋白酶原-2,采用免疫抑制法测定胰腺淀粉酶、酶偶联法测定α-淀粉酶.结果 69例AP患者中尿胰蛋白酶原-2阳性65例(94.2%),胰腺淀粉酶阳性63例(91.3%),α-淀粉酶阳性59例(85.5%);尿胰蛋白酶原-2诊断AP敏感性94.2%、特异性90.3%;胰腺淀粉酶诊断AP敏感性91.3%、特异性是87.1%;α-淀粉酶诊断AP敏感性85.5%、特异性74.2%.结论 尿胰蛋白酶原-2是诊断AP的较好检测指标.

  17. Effect of endothelin-1 receptor antagonists on histological and ultrastructural changes in the pancreas and trypsinogen activation in the early course of caerulein-induced acute pancreatitis in rats

    Institute of Scientific and Technical Information of China (English)

    Anna Andrzejewska; Jan W. Dlugosz; Albert Augustynowicz

    2005-01-01

    AIM: To assess the effect of non-selective ETA/B (LU 302872)and selective ETA (LU 302146) antagonist on pancreatic histology and ultrastructure of acinar cells in connection with trypsinogen activation in early caerulein-induced AP.METHODS: Male Wistar rats with caerulein-induced AP,lasting 4 h, were treated i.p. with 10 and 20 mg/kg b.w.of each antagonist. Edema, inflammatory infiltration,necrosis and vacuolization of acinar cells in the pancreas were scored at 0-3 scale. Free active trypsin (FAT), total potential trypsin (TPT) after activation with enterokinase,and index of trypsinogen activation (%FAT/TPT) were assayed in pancreatic homogenates.RESULTS: In untreated AP, the edema, inflammatory infiltration, necrosis and vacuolization increased as compared to control healthy rats (P<0.01). None of the treatment exerted any meaningful effect on the edema and inflammatory infiltration. The selective antagonist increased slightly the necrosis score to 0.82±0.06 at higher dose (P<0.05) vs 0.58±0.06 in untreated AP. The nonselective antagonist increased slightly the vacuolization score to 2.41±0.07 at higher dose (P<0.01) vs 1.88±0.08in untreated AP. The decrease in the number of zymogen granules, disorganization of endoplasmic reticulum,autophagosomes and cytoplasmic vacuoles were more prominent in treated AP than in untreated AP groups.%FAT/TPT in untreated AP increased about four times (18.4±3.8 vs4.8±1.3 in control group without AP, P<0.001).Treatment of AP with both antagonists did not affect significantly augmented trypsinogen activation.CONCLUSION: The treatment with endothelin-1 receptors (non-selective ETA/B and selective ETA) antagonists has essential effect neither on the edema and inflammatory infiltration nor on trypsinogen activation observed in the early course of caerulein-induced AP. Nevertheless a slight increase of the necrosis and vacuolization score and some of the ultrastructural data could suggest the possibility of their undesired

  18. Hereditary pancreatitis and secondary screening for early pancreatic cancer.

    Science.gov (United States)

    Vitone, L J; Greenhalf, W; Howes, N R; Neoptolemos, J P

    2005-01-01

    Hereditary pancreatitis is an autosomal dominant disease with incomplete penetrance (80%), accounting for approximately 1% of all cases of pancreatitis. It is characterized by the onset of recurrent attacks of acute pancreatitis in childhood and frequent progression to chronic pancreatitis. Whitcomb et al. identified the cationic trypsinogen gene (PRSS1) on chromosome 7q35 as the site of the mutation that causes hereditary pancreatitis. The European registry of hereditary pancreatitis and familial pancreatic cancer (EUROPAC) aims to identify and make provisions for those affected by hereditary pancreatitis and familial pancreatic cancer. The most common mutations in hereditary pancreatitis are R122H, N29I and A16V but many families have been described with clinically defined hereditary pancreatitis where there is no PRSS1 mutation. It is known that the cumulative lifetime risk (to age 70 years) of pancreatic cancer is 40% in individuals with hereditary pancreatitis. This subset of individuals form an ideal group for the development of a screening programme aimed at detecting pancreatic cancer at an early stage in an attempt to improve the presently poor long-term survival. Current screening strategies involve multimodality imaging (computed tomography, endoluminal ultrasound) and endoscopic retrograde cholangiopancreatography for pancreatic juice collection followed by molecular analysis of the DNA extracted from the juice. The potential benefit of screening (curative resection) must be balanced against the associated morbidity and mortality of surgery. Philosophically, the individual's best interest must be sought in light of the latest advances in medicine and science following discussions with a multidisciplinary team in specialist pancreatic centres.

  19. An overview of hereditary pancreatitis.

    Science.gov (United States)

    Rebours, Vinciane; Lévy, Philippe; Ruszniewski, Philippe

    2012-01-01

    Hereditary pancreatitis is a rare cause of chronic pancreatitis. The prevalence was evaluated to 0.3/100000 in Western Countries. Genetic disorders are due to mutations of the PRSS1 gene on the long arm of the chromosome 7, encoding for the cationic trypsinogen. The inheritance pattern is autosomal dominant with an incomplete penetrance (80%). Since 1996, more than 30 mutations were found. The three more common mutations are R122H, N29I and A16V. First symptoms begin since childhood, mainly before 10 years old. Main symptoms are pancreatic pain and acute pancreatitis (>70%). CP morphological changes as pancreatic calcifications are diagnosed at a median age of 22-25 years. Exocrine and endocrine pancreatic insufficiency occurred in 34% and 26% at a median age of 29 and 38 years. No clinical differences exist according to the mutation type. No excess of mortality in hereditary pancreatitis population compared to general population was found, despite a real risk of cancer. The cumulative risks of pancreatic cancer at 50, 60 and, 75 years are 10%, 18.7% and, 53.5%, respectively. The relative risk of cancer increases in smokers and is evaluated to 8.55. Hereditary pancreatitis diagnosis permits to propose an adapted management in expert centres.

  20. Synthetic cation-selective nanotube: Permeant cations chaperoned by anions

    Science.gov (United States)

    Hilder, Tamsyn A.; Gordon, Dan; Chung, Shin-Ho

    2011-01-01

    The ability to design ion-selective, synthetic nanotubes which mimic biological ion channels may have significant implications for the future treatment of bacteria, diseases, and as ultrasensitive biosensors. We present the design of a synthetic nanotube made from carbon atoms that selectively allows monovalent cations to move across and rejects all anions. The cation-selective nanotube mimics some of the salient properties of biological ion channels. Before practical nanodevices are successfully fabricated it is vital that proof-of-concept computational studies are performed. With this in mind we use molecular and stochastic dynamics simulations to characterize the dynamics of ion permeation across a single-walled (10, 10), 36 Å long, carbon nanotube terminated with carboxylic acid with an effective radius of 5.08 Å. Although cations encounter a high energy barrier of 7 kT, its height is drastically reduced by a chloride ion in the nanotube. The presence of a chloride ion near the pore entrance thus enables a cation to enter the pore and, once in the pore, it is chaperoned by the resident counterion across the narrow pore. The moment the chaperoned cation transits the pore, the counterion moves back to the entrance to ferry another ion. The synthetic nanotube has a high sodium conductance of 124 pS and shows linear current-voltage and current-concentration profiles. The cation-anion selectivity ratio ranges from 8 to 25, depending on the ionic concentrations in the reservoirs.

  1. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    and KCN, are selectively bound to the catalyst, providing exceptionally high enantioselectivities for kinetic resolutions, elimination reactions (fluoride base), and Strecker synthesis (cyanide nucleophile). Asymmetric cation-binding catalysis was recently expanded to silicon-based reagents, enabling...... solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...

  2. Research progress in cation-π interactions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cation-π interaction is a potent intermolecular interaction between a cation and an aromatic system,which has been viewed as a new kind of binding force,as being compared with the classical interactions(e.g. hydrogen bonding,electrostatic and hydrophobic interactions). Cation-π interactions have been observed in a wide range of biological contexts. In this paper,we present an overview of the typical cation-π interactions in biological systems,the experimental and theoretical investigations on cation-π interactions,as well as the research results on cation-π interactions in our group.

  3. Research progress in cation-π interactions

    Institute of Scientific and Technical Information of China (English)

    CHENG JiaGao; LUO XiaoMin; YAN XiuHua; LI Zhong; TANG Yun; JIANG HuaLiang; ZHU WeiLiang

    2008-01-01

    Cation-π interaction is a potent intermolecular interaction between a cation and an aromatic system, which has been viewed as a new kind of binding force, as being compared with the classical interac-tions (e.g. hydrogen bonding, electrostatic and hydrophobic interactions). Cation-π interactions have been observed in a wide range of biological contexts. In this paper, we present an overview of the typi-cal cation-π interactions in biological systems, the experimental and theoretical investigations on cation-π interactions, as well as the research results on cation-π interactions in our group.

  4. Heavy metal cations permeate the TRPV6 epithelial cation channel.

    Science.gov (United States)

    Kovacs, Gergely; Danko, Tamas; Bergeron, Marc J; Balazs, Bernadett; Suzuki, Yoshiro; Zsembery, Akos; Hediger, Matthias A

    2011-01-01

    TRPV6 belongs to the vanilloid family of the transient receptor potential channel (TRP) superfamily. This calcium-selective channel is highly expressed in the duodenum and the placenta, being responsible for calcium absorption in the body and fetus. Previous observations have suggested that TRPV6 is not only permeable to calcium but also to other divalent cations in epithelial tissues. In this study, we tested whether TRPV6 is indeed also permeable to cations such as zinc and cadmium. We found that the basal intracellular calcium concentration was higher in HEK293 cells transfected with hTRPV6 than in non-transfected cells, and that this difference almost disappeared in nominally calcium-free solution. Live cell imaging experiments with Fura-2 and NewPort Green DCF showed that overexpression of human TRPV6 increased the permeability for Ca(2+), Ba(2+), Sr(2+), Mn(2+), Zn(2+), Cd(2+), and interestingly also for La(3+) and Gd(3+). These results were confirmed using the patch clamp technique. (45)Ca uptake experiments showed that cadmium, lanthanum and gadolinium were also highly efficient inhibitors of TRPV6-mediated calcium influx at higher micromolar concentrations. Our results suggest that TRPV6 is not only involved in calcium transport but also in the transport of other divalent cations, including heavy metal ions, which may have toxicological implications.

  5. The adjuvant mechanism of cationic dimethyldioctadecylammonium liposomes

    DEFF Research Database (Denmark)

    Korsholm, Karen Smith; Agger, Else Marie; Foged, Camilla;

    2007-01-01

    Cationic liposomes are being used increasingly as efficient adjuvants for subunit vaccines but their precise mechanism of action is still unknown. Here, we investigated the adjuvant mechanism of cationic liposomes based on the synthetic amphiphile dimethyldioctadecylammonium (DDA). The liposomes ...

  6. Tripodal Receptors for Cation and Anion Sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman,; Verboom, Willem; Reinhoudt, David N.

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing

  7. Activated microglia enhance neurogenesis via trypsinogen secretion.

    Science.gov (United States)

    Nikolakopoulou, Angeliki M; Dutta, Ranjan; Chen, Zhihong; Miller, Robert H; Trapp, Bruce D

    2013-05-21

    White matter neurons in multiple sclerosis brains are destroyed during demyelination and then replaced in some chronic multiple sclerosis lesions that exhibit a morphologically distinct population of activated microglia [Chang A, et al. (2008) Brain 131(Pt 9):2366-2375]. Here we investigated whether activated microglia secrete factors that promote the generation of neurons from white matter cells. Adult rat brain microglia (resting or activated with lipopolysaccharide) were isolated by flow cytometry and cocultured with neonatal rat optic nerve cells in separate but media-connected chambers. Optic nerve cells cocultured with activated microglia showed a significant increase in the number of cells of neuronal phenotype, identified by neuron-specific class III beta-tubulin (TUJ-1) labeling, compared with cultures with resting microglia. To investigate the possible source of the TUJ-1-positive cells, A2B5-positive oligodendrocyte progenitor cells and A2B5-negative cells were isolated and cocultured with resting and activated microglia. Significantly more TUJ-1-positive cells were generated from A2B5-negative cells (∼70%) than from A2B5-positive cells (~30%). Mass spectrometry analysis of microglia culture media identified protease serine 2 (PRSS2) as a factor secreted by activated, but not resting, microglia. When added to optic nerve cultures, PRSS2 significantly increased neurogenesis, whereas the serine protease inhibitor, secretory leukocyte protease inhibitor, decreased activated microglia-induced neurogenesis. Collectively our data provide evidence that activated microglia increase neurogenesis through secretion of PRSS2.

  8. 尿胰蛋白酶原-2快速检测在急性胰腺炎早期诊断中的应用%Appling rapid urine trypsinogen-2 test to early diagnosis of acute pancreatitis

    Institute of Scientific and Technical Information of China (English)

    汪丽儿

    2013-01-01

    Objective:To assess the value of rapid measurement of urina-ry trypsinogen-2(TPS-2)for early diagnosis of acute pancreatitis(AP). Methods:Blood and urine amylase,lipase and TPS-2 were determined in 88 emergency cases or inpatients with acute abdominal pain for initial di-agnosis on the Guidelines for Diagnosis and Treatment of Acute Pancreati-tis in China basis.The total patients were then allocated to group of AP and non-AP,and the diagnostic accuracy of the markers of TPS-2 were e-valuated by receiver-operating characteristic( ROC) curve analysis pertain-ing to the urine TPS-2,serum amylase and urine amylase as well as re-solved time of TPS-2 in the urine.Results:The specificity and sensitivity for AP by determination of TPS-2 were 89.2% and 97.1%,and the nega-tive predictive value,positive predictive value and accuracy of urine TPS-2 were 97.1%,92.2% and 94.1%,respectively.The difference was not significant with the reference values of serum amylase(P>0.05),yet was significant compared with urine amylase(P<0.05).The area under the curve of the ROC plot described urine TPS-2,serum amylase and urine amylase by 0.860,0.823 and 0.821, respectively.Conclusion:Urine TPS-2 dipstick test may be simple and quick for early diagnosis of AP for its higher specificity,sensitivity and accuracy.%目的:评价尿胰蛋白酶原-2快速检测在急性胰腺炎早期诊断中的价值。方法:检测85例因急性腹痛而就诊的急诊或住院的病人血、尿淀粉酶,血脂肪酶及尿胰蛋白酶原-2,按照《胰腺炎诊断标准》判断是否患有胰腺炎,分为急性胰腺炎组和非急性胰腺炎组,计算尿胰蛋白酶原-2阳性诊断急性胰腺炎的性能指标,以临床诊断急性胰腺炎统计尿胰蛋白酶原-2、血淀粉酶、尿淀粉酶的ROC曲线及尿胰蛋白酶原-2阳性在尿液中持续时间。结果:尿胰蛋白酶原-2诊断急性胰腺炎的特异度89.2%,敏感度97.9%,阴性预示值97.1

  9. Identification of serum biomarkers for occupational medicamentosa-like dermatitis induced by trichloroethylene using mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Wen-Xu; Liu, Wei [Key Laboratory of Modern Toxicology of Shenzhen, Medical Key Laboratory of Guangdong Province, Medical Key Laboratory of Health Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055 (China); Zhang, Yanfang [Shenzhen Prevention and Treatment Center for Occupational Disease, Shenzhen 518001 (China); Huang, Peiwu; Yang, Xifei; Ren, Xiaohu; Ye, Jinbo; Huang, Haiyan [Key Laboratory of Modern Toxicology of Shenzhen, Medical Key Laboratory of Guangdong Province, Medical Key Laboratory of Health Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055 (China); Tang, Haiyan [Shenzhen Prevention and Treatment Center for Occupational Disease, Shenzhen 518001 (China); Zhou, Guifeng [Medical School of Hunan Normal University, Changsha 410006 (China); Huang, Xinfeng; Zhuang, Zhixiong [Key Laboratory of Modern Toxicology of Shenzhen, Medical Key Laboratory of Guangdong Province, Medical Key Laboratory of Health Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055 (China); Liu, Jianjun, E-mail: bio-research@hotmail.com [Key Laboratory of Modern Toxicology of Shenzhen, Medical Key Laboratory of Guangdong Province, Medical Key Laboratory of Health Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055 (China)

    2013-11-15

    Occupational medicamentosa-like dermatitis induced by trichloroethylene (OMLDT) is an autoimmune disease and it has become a serious occupational health hazard. In the present study, we collected fasting blood samples from patients with OMLDT (n = 18) and healthy volunteers (n = 33) to explore serum peptidome patterns. Peptides in sera were purified using weak cation exchange magnetic beads (MB-WCX), and analyzed by matrix-assisted laser desorption ionization time-of-flight-mass spectrometry (MALDI-TOF-MS) and ClinProTools bioinformatics software. The intensities of thirty protein/peptide peaks were significantly different between the healthy control and OMLDT patients. A pattern of three peaks (m/z 2106.3, 2134.5, and 3263.67) was selected for supervised neural network (SNN) model building to separate the OMLDT patients from the healthy controls with a sensitivity of 95.5% and a specificity of 73.8%. Furthermore, two peptide peaks of m/z 4091.61 and 4281.69 were identified as fragments of ATP-binding cassette transporter family A member 12 (ABCA12), and cationic trypsinogen (PRRS1), respectively. Our findings not only show that specific proteomic fingerprints in the sera of OMLDT patients can be served as a differentiated tool of OMLDT patients with high sensitivity and high specificity, but also reveal the novel correlation between OMLDT with ABC transports and PRRS1, which will be of potential value for clinical and mechanistic studies of OMLDT. - Highlights: • Identify 30 differential protein/peptide peaks between OMLDT and healthy control • The test sensitivity and test specificity were 95.5% and 73.8%, respectively. • ABCA12 and PRSS1 were identified as potential biomarkers in OMLDT patients.

  10. The Free Tricoordinated Silyl Cation Problem

    Directory of Open Access Journals (Sweden)

    Čičak, H.

    2010-03-01

    Full Text Available As the importance and abundance of silicon in our environment is large, it has been thought that silicon might take the place of carbon in forming a host of similar compounds and silicon-based life. However, until today there is no experimental evidence for such a hypothesis and carbon is still unique among the elements in the vast number and variety of compounds it can form. Also, the corresponding derivatives of the two elements show considerable differences in their chemical properties.The essential debate concerning organosilicon chemistry relates to the existence of the free planar tricoordinated silyl cations in condensed phase (R3Si+, in analogy to carbocations (R3C+ which have been known and characterized as free species. Although silyl cations are thermodynamically more stable than their carbon analogs, they are very reactive due to their high inherent electrophilicity and the ability of hypervalent coordination. On the other hand, stabilization by inductive and hyperconjugative effects and larger steric effects of carbocations make them less sensitive to solvation or other environmental effects than silyl cations. Hence, observation of free silyl cations in the condensed phase proved extremely difficult and the actual problem is the question of the degree of the (remaining silyl cation character.The first free silyl cation, trimesitylsilyl cation, and in analogy with it tridurylsilyl cation, were synthesized by Lambert et al. Free silyl cations based on analogy to aromatic ions (homocyclopropenylium and tropylium have also been prepared. However, in these silyl cations the cationic character is reduced by internal π -conjugation. Čičak et al. prepared some silyl-cationic intermediates (Me3Si--CH≡CR+in solid state. With the help of quantum-mechanical calculations it was concluded that these adducts have much more silyl cation than carbocation character.

  11. Afrikaans Syllabification Patterns

    Directory of Open Access Journals (Sweden)

    Tilla Fick

    2010-01-01

    Full Text Available In contrast to English, automatic hyphenation by computer of Afrikaans words is a problem that still needs to be addressed, since errors are still often encountered in printed text. An initial step in this task is the ability to automatically syllabify words. Since new words are created continuously by joining words, it is necessary to develop an “intelligent” technique for syllabification. As a first phase of the research, we consider only the orthographic information of words, and disregard both syntactic and morphological information. This approach allows us to use machine-learning techniques such as artificial neural networks and decision trees that are known for their pattern recognition abilities. Both these techniques are trained with isolated patterns consisting of input patterns and corresponding outputs (or targets that indicate whether the input pattern should be split at a certain position, or not. In the process of compiling a list of syllabified words from which to generate training data for the  syllabification problem, irregular patterns were identified. The same letter patterns are split differently in different words and complete words that are spelled identically are split differently due to meaning. We also identified irregularities in and between  the different dictionaries that we used. We examined the influence range of letters that are involved in irregularities. For example, for their in agter-ente and vaste-rente we have to consider three letters to the left of r to be certain where the hyphen should be inserted. The influence range of the k in verstek-waarde and kleinste-kwadrate is four to the left and three to the right. In an analysis of letter patterns in Afrikaans words we found that the letter e has the highest frequency overall (16,2% of all letters in the word list. The frequency of words starting with s is the highest, while the frequency of words ending with e is the highest. It is important to

  12. Localization versus delocalization in diamine radical cations

    DEFF Research Database (Denmark)

    Brouwer, A.M.; Wiering, P.G.; Zwier, J.M.;

    1997-01-01

    The optical absorption spectrum of the radical cation of 1,4-diphenylpiperazine 2a shows a strong transition in the near-IR, and only a weak band at 445 nm, in the region where aniline radical cations normally absorb strongly. This indicates that the charge and spin are delocalized over the two...

  13. Advancements in Anion Exchange Membrane Cations

    Energy Technology Data Exchange (ETDEWEB)

    Sturgeon, Matthew R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Long, Hai [National Renewable Energy Lab. (NREL), Golden, CO (United States); Park, Andrew M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Pivovar, Bryan S. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-10-15

    Anion-exchange membrane fuel cells (AME-FCs) are of increasingly popular interest as they enable the use of non-Pt fuel cell catalysts, the primary cost limitation of proton exchange membrane fuel cells. Benzyltrimethyl ammonium (BTMA) is the standard cation that has historically been utilized as the hydroxide conductor in AEMs. Herein we approach AEMs from two directions. First and foremost we study the stability of several different cations in a hydroxide solution at elevated temperatures. We specifically targeted BTMA and methoxy and nitro substituted BTMA. We've also studied the effects of adding an akyl spacer units between the ammonium cation and the phenyl group. In the second approach we use computational studies to predict stable ammonium cations, which are then synthesized and tested for stability. Our unique method to study cation stability in caustic conditions at elevated temperatures utilizes Teflon Parr reactors suitable for use under various temperatures and cation concentrations. NMR analysis was used to determine remaining cation concentrations at specific time points with GCMS analysis verifying product distribution. We then compare the experimental results with calculated modeling stabilities. Our studies show that the electron donating methoxy groups slightly increase stability (compared to that of BTMA), while the electron withdrawing nitro groups greatly decrease stability in base. These results give insight into possible linking strategies to be employed when tethering a BTMA like ammonium cation to a polymeric backbone; thus synthesizing an anion exchange membrane.

  14. Cation diffusion in the natural zeolite clinoptilolite

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, A.; White, K.J. [Science Research Institute, Chemistry Division, Cockcroft Building, University of Salford, Salford (United Kingdom)

    1999-12-14

    The natural zeolite clinoptilolite is mined commercially in many parts of the world. It is a selective exchanger for the ammonium cation and this has prompted its use in waste water treatment, swimming pools and in fish farming. It is also used to scavenge radioisotopes in nuclear waste clean-up. Further potential uses for clinoptilolite are in soil amendment and remediation. The work described herein provides thermodynamic data on cation exchange processes in clinoptilolite involving the NH{sub 4}, Na, K, Ca, and Mg cations. The data includes estimates of interdiffusion coefficients together with free energies, entropies and energies of activation for the cation exchanges studied. Suggestions are made as to the mechanisms of cation-exchanges involved.

  15. [Hereditary aspects of pancreatitis].

    Science.gov (United States)

    Bak, Daniel; Sobczyńska-Tomaszewska, Agnieszka; Bal, Jerzy

    2003-01-01

    Pancreatitis presents clinically as acute and chronic form. A common characteristic of these two forms is enzymatic autodigestion of pancreas in the course of the disease. It results from premature activation of pancreatic digestive enzymes and disturbance of subtle balance between proteolytic enzymes and their inhibitors. The way to understand the character of mechanisms leading to development of pancreatitis has been simplified by discovery of genetic factors, which are able to initiate pathological changes at tissue level. Mutations in the PRSS1 gene (first of all R122H and N29I mutations), which encodes for cationic trypsin, cause trypsin to be protected from autodegradation. These mutations also cause precursor of trypsin - trypsinogen, to be activated easier. On the other hand mutations in the SPINK1 gene have been identified. SPINK1 gene encodes for the most important protease inhibitor of the pancreatic fluid. The most frequent mutation, namely N34S, decrease SPINK1 protein in its activity. The link between the genotype and phenotype is not clear in every case. It is probable that pancreatitis will be recognized as poligenic with many genes engaged in the disease development. Pancreatic cancer is a frequent consequence of pancreatitis. It is a very invasive cancer with high mortality. In the course of pancreatic inflammation intensive cell proliferation takes place for regeneration of pancreas damage. It is the chance for amplification of pathological changes in DNA, which have arisen as a ROS's (Reactive Oxygen Species) and RNOS's (Reactive Nitrogen Oxide Species) action effect. ROS and RNOS are generated in the course of pancreas inflammation.

  16. Cationic Bolaamphiphiles for Gene Delivery

    Science.gov (United States)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad

    2014-05-01

    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  17. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  18. Cationic ruthenium alkylidene catalysts bearing phosphine ligands.

    Science.gov (United States)

    Endo, Koji; Grubbs, Robert H

    2016-02-28

    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bearing bulky phosphine ligands. Simple ligand exchange using silver(i) salts of non-coordinating or weakly coordinating anions provided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported catalysts feature unique geometries caused by ligation of the bulky phosphine ligands. Their activities and selectivities in standard metathesis reactions were also investigated. These cationic ruthenium alkylidene catalysts reported here showed moderate activity and very similar stereoselectivity when compared to the second generation ruthenium dichloride catalyst in ring-closing metathesis, cross metathesis, and ring-opening metathesis polymerization assays.

  19. Cation locations and dislocations in zeolites

    Science.gov (United States)

    Smith, Luis James

    The focus of this dissertation is the extra-framework cation sites in a particular structural family of zeolites, chabazite. Cation sites play a particularly important role in the application of these sieves for ion exchange, gas separation, catalysis, and, when the cation is a proton, acid catalysis. Structural characterization is commonly performed through the use of powder diffraction and Rietveld analysis of powder diffraction data. Use of high-resolution nuclear magnetic resonance, in the study of the local order of the various constituent nuclei of zeolites, complements well the long-range order information produced by diffraction. Recent developments in solid state NMR techniques allow for increased study of disorder in zeolites particularly when such phenomena test the detection limits of diffraction. These two powerful characterization techniques, powder diffraction and NMR, offer many insights into the complex interaction of cations with the zeolite framework. The acids site locations in SSZ-13, a high silica chabazite, and SAPO-34, a silicoaluminophosphate with the chabazite structure, were determined. The structure of SAPO-34 upon selective hydration was also determined. The insensitivity of X-rays to hydrogen was avoided through deuteration of the acid zeolites and neutron powder diffraction methods. Protons at inequivalent positions were found to have different acid strengths in both SSZ-13 and SAPO-34. Other light elements are incorporated into zeolites in the form of extra-framework cations, among these are lithium, sodium, and calcium. Not amenable by X-ray powder diffraction methods, the positions of such light cations in fully ion-exchanged versions of synthetic chabazite were determined through neutron powder diffraction methods. The study of more complex binary cation systems were conducted. Powder diffraction and solid state NMR methods (MAS, MQMAS) were used to examine cation site preferences and dislocations in these mixed-akali chabazites

  20. Cationized Carbohydrate Gas-Phase Fragmentation Chemistry

    Science.gov (United States)

    Bythell, Benjamin J.; Abutokaikah, Maha T.; Wagoner, Ashley R.; Guan, Shanshan; Rabus, Jordan M.

    2016-11-01

    We investigate the fragmentation chemistry of cationized carbohydrates using a combination of tandem mass spectrometry, regioselective labeling, and computational methods. Our model system is D-lactose. Barriers to the fundamental glyosidic bond cleavage reactions, neutral loss pathways, and structurally informative cross-ring cleavages are investigated. The most energetically favorable conformations of cationized D-lactose were found to be similar. In agreement with the literature, larger group I cations result in structures with increased cation coordination number which require greater collision energy to dissociate. In contrast with earlier proposals, the B n -Y m fragmentation pathways of both protonated and sodium-cationized analytes proceed via protonation of the glycosidic oxygen with concerted glycosidic bond cleavage. Additionally, for the sodiated congeners our calculations support sodiated 1,6-anhydrogalactose B n ion structures, unlike the preceding literature. This affects the subsequent propensity of formation and prediction of B n /Y m branching ratio. The nature of the anomeric center (α/β) affects the relative energies of these processes, but not the overall ranking. Low-energy cross-ring cleavages are observed for the metal-cationized analytes with a retro-aldol mechanism producing the 0,2 A 2 ion from the sodiated forms. Theory and experiment support the importance of consecutive fragmentation processes, particularly for the protonated congeners at higher collision energies.

  1. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation

    Science.gov (United States)

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-01

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  2. Valor diagnóstico y pronóstico de la determinación de tripsinógeno-2 urinario en pacientes con pancreatitis aguda Usefulness of determining urinary trypsinogen-2 in diagnosis and prognosis of patients with acute pancreatitis

    Directory of Open Access Journals (Sweden)

    J.A. Díaz Peromingo

    2009-12-01

    Full Text Available Fundamento. Estudiar el papel del tripsinógeno-2 urinario en el diagnóstico y pronóstico inicial de pacientes con pancreatitis aguda (PA así como su relación con la estancia media hospitalaria y la mortalidad. Método. Se incluyeron 42 pacientes diagnosticados de PA a los que se realizó hematimetría, bioquímica sanguínea, amilasuria y tripsinógeno-2 urinario. Se estableció un punto de corte de 50 µg/L y una segunda dilución a 2.000 µg/L. Otras variables incluidas fueron etiología, estancia media hospitalaria, traslado a UCI y fallecimiento. Resultados. De los 42 pacientes, 29 (69% eran hombres y 13 (31% mujeres; edad media 61 años. La etiología más frecuente era la biliar, seguida del alcohol. Estancia media: 8,38 días. Traslado a UCI en 4 (9,5% pacientes. Dos de los pacientes trasladados a UCI y otro que no requirió traslado fallecieron (7,14%. La amilasa sérica fue elevada en 33 (78,57% pacientes y la lipasa en 36 (85,71%. El tripsinógeno urinario fue positivo en 34 pacientes (80,95%. Se evidenció asociación entre tripsinógeno-2 urinario y edad (p=0,016; r=0,893, glucemia (p=0,005, r=0,901, amilasa plasmática (p=0,029; r=0,852, lipasa (p=0,022; r=0,809 e hipoxemia (p=0,001; r=0,962. En cuanto a la estancia media, se observó asociación estadística con edad (p=0,046; r=0,784 y acidosis metabólica (p=0,016; r=0,839. La mortalidad se asoció a hipocalcemia (p=0,008; r=0,899 y acidosis metabólica (p=0,032; r=0,814. Conclusión. La determinación del tripsinógeno-2 urinario en pacientes con PA es un test útil y rápido. Los pacientes mayores de 65 años, con hipoxemia, acidosis metabólica e hipocalcemia tienen tendencia a presentar una estancia media hospitalaria prolongada y mayor mortalidad.Background. To study the role of urinary trypsinogen-2 in diagnosing and early prognosis of patients with acute pancreatitis (AP and the relationship to length of hospital stay and mortality. Methods. Forty-two patients were

  3. Cation Effect on Copper Chemical Mechanical Polishing

    Institute of Scientific and Technical Information of China (English)

    WANG Liang-Yong; LIU Bo; SONG Zhi-Tang; FENG Song-Lin

    2009-01-01

    We examine the effect of cations in solutions containing benzotriazole (BTA) and H2O2 on copper chemical mechanical polishing (CMP). On the base of atomic force microscopy (AFM) and material removal rate (MRR) results, it is found that ammonia shows the highest MRR as well as good surface after CMP, while KOH demon-strates the worst performance. These results reveal a mechanism that sma//molecules with lone-pairs rather than molecules with steric effect and common inorganic cations are better for copper CMP process, which is indirectly confirmed by open circuit potential (OCP).

  4. Cation Effect on Copper Chemical Mechanical Polishing

    Science.gov (United States)

    Wang, Liang-Yong; Liu, Bo; Song, Zhi-Tang; Feng, Song-Lin

    2009-02-01

    We examine the effect of cations in solutions containing benzotriazole (BTA) and H2O2 on copper chemical mechanical polishing (CMP). On the base of atomic force microscopy (AFM) and material removal rate (MRR) results, it is found that ammonia shows the highest MRR as well as good surface after CMP, while KOH demonstrates the worst performance. These results reveal a mechanism that small molecules with lone-pairs rather than molecules with steric effect and common inorganic cations are better for copper CMP process, which is indirectly confirmed by open circuit potential (OCP).

  5. Cationically polymerizable monomers derived from renewable sources

    Energy Technology Data Exchange (ETDEWEB)

    Crivello, J.V.

    1992-10-01

    The objectives of this project are to design and synthesize novel monomers which orginate from renewable biological sources and to carry out their rapid, efficient, pollution-free and energy efficient cationic polymerization to useful products under the influence of ultraviolet light or heat. A summary of the results of the past year's research on cationically polymerizable monomers derived from renewable sources is presented. Three major areas of investigation corresponding to the different classes of naturally occurring starting materials were investigated; epoxidized terpenes and natural rubber and vinyl ethers from alcohols and carbohydrates.

  6. Cationic dialkylarylphosphates: a new family of bio-inspired cationic lipids for gene delivery.

    Science.gov (United States)

    Le Corre, Stéphanie S; Belmadi, Nawal; Berchel, Mathieu; Le Gall, Tony; Haelters, Jean-Pierre; Lehn, Pierre; Montier, Tristan; Jaffrès, Paul-Alain

    2015-01-28

    In this work that aims to synthesize and evaluate new cationic lipids as vectors for gene delivery, we report the synthesis of a series of cationic lipids in which a phosphate functional group acts as a linker to assemble on a molecular scale, two lipid chains and one cationic polar head. The mono or dicationic moiety is connected to the phosphate group by an aryl spacer. In this work, two synthesis strategies were evaluated. The first used the Atherton-Todd coupling reaction to introduce a phenolic derivative to dioleylphosphite. The second strategy used a sequential addition of lipid alcohol and a phenolic derivative on POCl3. The two methods are efficient, but the latter allows larger yields. Different polar head groups were introduced, thus producing amphiphilic compounds possessing either one permanent (N-methyl-imidazolium, pyridinium, trimethylammonium) or two permanent cationic charges. All these cationic lipids were formulated as liposomal solutions and characterized (size and zeta potential). They formed stable liposomal solutions both in water (at pH 7.0) and in a weakly acidic medium (at pH 5.5). Finally, this new generation of cationic lipids was used to deliver DNA into various human-derived epithelial cells cultured in vitro. Compared with Lipofectamine used as a reference commercial lipofection reagent, some cationic dialkylarylphosphates were able to demonstrate potent gene transfer abilities, and noteworthily, monocationic derivatives were much more efficient than dicationic analogues.

  7. Cation Selectivity in Biological Cation Channels Using Experimental Structural Information and Statistical Mechanical Simulation.

    Science.gov (United States)

    Finnerty, Justin John; Peyser, Alexander; Carloni, Paolo

    2015-01-01

    Cation selective channels constitute the gate for ion currents through the cell membrane. Here we present an improved statistical mechanical model based on atomistic structural information, cation hydration state and without tuned parameters that reproduces the selectivity of biological Na+ and Ca2+ ion channels. The importance of the inclusion of step-wise cation hydration in these results confirms the essential role partial dehydration plays in the bacterial Na+ channels. The model, proven reliable against experimental data, could be straightforwardly used for designing Na+ and Ca2+ selective nanopores.

  8. Mixed cation effect in sodium aluminosilicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Mauro, John C.

    , network structure, and the resistances associated with the deformation processes in mixed cation glasses by partially substituting magnesium for calcium and calcium for lithium in sodium aluminosilicate glasses. We use Raman and 27Al NMR spectroscopies to obtain insights into the structural...

  9. Resonance raman studies of phenylcyclopropane radical cations

    NARCIS (Netherlands)

    Godbout, J.T.; Zuilhof, H.; Heim, G.; Gould, I.R.; Goodman, J.L.; Dinnocenzo, J.P.; Myers Kelley, A.

    2000-01-01

    Resonance Raman spectra of the radical cations of phenylcyclopropane and trans-1-phenyl-2-methylcyclopropane are reported. A near-UV pump pulse excites a photosensitizer which oxidizes the species of interest, and a visible probe pulse delayed by 35 ns obtains the spectrum of the radical ion. The tr

  10. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.;

    2003-01-01

    Polypyrrole (PPy) polymer films permanently doped with large, immobile anion dodecyl benzene sulfonate (DBS) have been characterized by cyclic voltammetry in order to clarify the roles of cations and anions in the aqueous electrolyte as mobile ions in the film. Aqueous solutions of 0.05-0.1 M...... alkali metal chlorides as well as BaCl2, NaBr and (CH3CH2CH2)(4)NBr were used to investigate the effects of both the ionic charge, size and shape. In 1: 1 electrolytes using small ions only three peaks are present: a sharp cathodic peak at ca. - 0.6 V vs, SCE representing both the insertion of cations...... complicating reproducibility when employing PPy(DBS) polymers as actuators. When the cation is doubly charged, it enters the film less readily, and anions dominate the mobility. Using a large and bulky cation switches the mechanism to apparently total anion motion. The changes in area of the three peaks...

  11. Anionic/cationic complexes in hair care.

    Science.gov (United States)

    O'Lenick, Tony

    2011-01-01

    The formulation of cosmetic products is always more complicated than studying the individual components in aqueous solution. This is because there are numerous interactions between the components, which make the formulation truly more than the sum of the parts. This article will look at interactions between anionic and cationic surfactants and offer insights into how to use these interactions advantageously in making formulations.

  12. Controlled Cationic Polymerization of N-Vinylcarbazol

    NARCIS (Netherlands)

    Nuyken, O.; Rieß, G.; Loontjens, J.A.

    1995-01-01

    Cationic polymerization of N-Vinylcarbazol (NVC) was initiated with 1-iodo-1-(2-methylpropyloxy)ethane in the presence of N(n-Bu)4ClO4 and without addition of this activator. Furthermore, 1-chloro-1-(2-methylpropyloxy) ethane, with and without activator has been applied as initiator for NVC. These i

  13. Cationic lipids and cationic ligands induce DNA helix denaturation: detection of single stranded regions by KMnO4 probing.

    Science.gov (United States)

    Prasad, T K; Gopal, Vijaya; Rao, N Madhusudhana

    2003-09-25

    Cationic lipids and cationic polymers are widely used in gene delivery. Using 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) as a cationic lipid, we have investigated the stability of the DNA in DOTAP:DNA complexes by probing with potassium permanganate (KMnO4). Interestingly, thymidines followed by a purine showed higher susceptibility to cationic ligand-mediated melting. Similar studies performed with other water-soluble cationic ligands such as polylysine, protamine sulfate and polyethyleneimine also demonstrated melting of the DNA but with variations. Small cations such as spermine and spermidine and a cationic detergent, cetyl trimethylammonium bromide, also rendered the DNA susceptible to modification by KMnO4. The data presented here provide direct proof for melting of DNA upon interaction with cationic lipids. Structural changes subsequent to binding of cationic lipids/ligands to DNA may lead to instability and formation of DNA bubbles in double-stranded DNA.

  14. Dendritic Cells Stimulated by Cationic Liposomes.

    Science.gov (United States)

    Vitor, Micaela Tamara; Bergami-Santos, Patrícia Cruz; Cruz, Karen Steponavicius Piedade; Pinho, Mariana Pereira; Barbuto, José Alexandre Marzagão; De La Torre, Lucimara Gaziola

    2016-01-01

    Immunotherapy of cancer aims to harness the immune system to detect and destroy cancer cells. To induce an immune response against cancer, activated dendritic cells (DCs) must present tumor antigens to T lymphocytes of patients. However, cancer patients' DCs are frequently defective, therefore, they are prone to induce rather tolerance than immune responses. In this context, loading tumor antigens into DCs and, at the same time, activating these cells, is a tempting goal within the field. Thus, we investigated the effects of cationic liposomes on the DCs differentiation/maturation, evaluating their surface phenotype and ability to stimulate T lymphocytes proliferation in vitro. The cationic liposomes composed by egg phosphatidylcholine, 1,2-dioleoyl-3-trimethylammonium propane and 1,2-dioleoylphosphatidylethanolamine (50/25/25% molar) were prepared by the thin film method followed by extrusion (65 nm, polydispersity of 0.13) and by the dehydration-rehydration method (95% of the population 107 nm, polydispersity of 0.52). The phenotypic analysis of dendritic cells and the analysis of T lymphocyte proliferation were performed by flow cytometry and showed that both cationic liposomes were incorporated and activated dendritic cells. Extruded liposomes were better incorporated and induced higher CD86 expression for dendritic cells than dehydrated-rehydrated vesicles. Furthermore, dendritic cells which internalized extruded liposomes also provided stronger T lymphocyte stimulation. Thus, cationic liposomes with a smaller size and polydispersity seem to be better incorporated by dendritic cells. Hence, these cationic liposomes could be used as a potential tool in further cancer immunotherapy strategies and contribute to new strategies in immunotherapy.

  15. Bithiophene radical cation: Resonance Raman spectroscopy and molecular orbital calculations

    DEFF Research Database (Denmark)

    Grage, M.M.-L.; Keszthelyi, T.; Offersgaard, J.F.

    1998-01-01

    The resonance Raman spectrum of the photogenerated radical cation of bithiophene is reported. The bithiophene radical cation was produced via a photoinduced electron transfer reaction between excited bithiophene and the electron acceptor fumaronitrile in a room temperature acetonitrile solution a...

  16. THE CATIONIC ADDITIVES USED IN COATED INK-JET PAPER

    Institute of Scientific and Technical Information of China (English)

    Dongmei Yu; Chuanshan Zhao; Kefu Chen

    2004-01-01

    This study investigated the effects of several different cationic additives on the viscosity 、zeta potential and printing properties of the ink-jet coating. The cationic additives have greatly improved sheet's gloss and printabilities.

  17. Ion dynamics in cationic lipid bilayer systems in saline solutions

    DEFF Research Database (Denmark)

    Miettinen, Markus S; Gurtovenko, Andrey A; Vattulainen, Ilpo

    2009-01-01

    mixture of cationic dimyristoyltrimethylammoniumpropane (DMTAP) and zwitterionic (neutral) dimyristoylphosphatidylcholine (DMPC) lipids. Using atomistic molecular dynamics simulations, we address the effects of bilayer composition (cationic to zwitterionic lipid fraction) and of NaCl electrolyte...

  18. Production of sulfonated cation-exchangers from petroleum asphaltites

    Energy Technology Data Exchange (ETDEWEB)

    Pokonova, Yu.V.; Pol' kin, G.B.; Proskuryakov, V.A.; Vinogradov, M.V.

    1982-02-10

    Continuing our studies of the preparation of products of practical value from asphaltite, a new by-product of oil refining, we obtained sulfonated cation-exchangers from a mixture of asphaltite and acid tar. It is shown that these cation-exchangers have good kinetic properties and are superior in thermal and thermohydrolytic stability to the commercial cation-exchange resin KU-2.

  19. Cation Permeability in Soybean Aleurone Layer

    OpenAIRE

    Noda, Hiroko; Fukuda, Mitsuru

    1998-01-01

    The permeation of water and ions into bean seeds is essential for processing and cooking of beans. The permeability of cations, K, Na, Ca, and Mg ions, into soybean seed tissue, especially aleurone layer, during water uptake was investigated to characterize the ion permeation into soybeans. Aleurone layers and seed coats contained relatively high concentration of endogenous K and Ca ions, and endogenous Ca ion, respectively. The amounts of Ca ion entered seed coats and aleurone layers were gr...

  20. Limited data speaker identification

    Indian Academy of Sciences (India)

    H S Jayanna; S R Mahadeva Prasanna

    2010-10-01

    In this paper, the task of identifying the speaker using limited training and testing data is addressed. Speaker identification system is viewed as four stages namely, analysis, feature extraction, modelling and testing. The speaker identification performance depends on the techniques employed in these stages. As demonstrated by different experiments, in case of limited training and testing data condition, owing to less data, existing techniques in each stage will not provide good performance. This work demonstrates the following: multiple frame size and rate (MFSR) analysis provides improvement in the analysis stage, combination of mel frequency cepstral coefficients (MFCC), its temporal derivatives $(\\Delta,\\Delta \\Delta)$, linear prediction residual (LPR) and linear prediction residual phase (LPRP) features provides improvement in the feature extraction stage and combination of learning vector quantization (LVQ) and gaussian mixture model – universal background model (GMM–UBM) provides improvement in the modelling stage. The performance is further improved by integrating the proposed techniques at the respective stages and combining the evidences from them at the testing stage. To achieve this, we propose strength voting (SV), weighted borda count (WBC) and supporting systems (SS) as combining methods at the abstract, rank and measurement levels, respectively. Finally, the proposed hierarchical combination (HC) method integrating these three methods provides significant improvement in the performance. Based on these explorations, this work proposes a scheme for speaker identification under limited training and testing data.

  1. Controlling chemistry with cations: photochemistry within zeolites.

    Science.gov (United States)

    Ramamurthy, V; Shailaja, J; Kaanumalle, Lakshmi S; Sunoj, R B; Chandrasekhar, J

    2003-08-21

    The alkali ions present in the supercages of zeolites X and Y interact with included guest molecules through quadrupolar (cation-pi), and dipolar (cation-carbonyl) interactions. The presence of such interactions can be inferred through solid-state NMR spectra of the guest molecules. Alkali ions, as illustrated in this article, can be exploited to control the photochemical and photophysical behaviors of the guest molecules. For example, molecules that rarely phosphoresce can be induced to do so within heavy cation-exchanged zeolites. The nature (electronic configuration) of the lowest triplet state of carbonyl compounds can be altered with the help of light alkali metal ions. This state switch (n pi*-pi pi*) helps to bring out reactivity that normally remains dormant. Selectivity obtained during the singlet oxygen oxidation of olefins within zeolites illustrates the remarkable control that can be exerted on photoreactions with the help of a confined medium that also has active sites. The reaction cavities of zeolites, like enzymes, are not only well-defined and confined, but also have active sites that closely guide the reactant molecule from start to finish. The examples provided here illustrate that zeolites are far more useful than simple shape-selective catalysts.

  2. Cell volume-regulated cation channels.

    Science.gov (United States)

    Wehner, Frank

    2006-01-01

    Considering the enormous turnover rates of ion channels when compared to carriers it is quite obvious that channel-mediated ion transport may serve as a rapid and efficient mechanism of cell volume regulation. Whenever studied in a quantitative fashion the hypertonic activation of non-selective cation channels is found to be the main mechanism of regulatory volume increase (RVI). Some channels are inhibited by amiloride (and may be related to the ENaC), others are blocked by Gd(3) and flufenamate (and possibly linked to the group of transient receptor potential (TRP) channels). Nevertheless, the actual architecture of hypertonicity-induced cation channels remains to be defined. In some preparations, hypertonic stress decreases K(+) channel activity so reducing the continuous K(+) leak out of the cell; this is equivalent to a net gain of cell osmolytes facilitating RVI. The hypotonic activation of K(+) selective channels appears to be one of the most common principles of regulatory volume decrease (RVD) and, in most instances, the actual channels involved could be identified on the molecular level. These are BKCa (or maxi K(+)) channels, IK(Ca) and SK(Ca) channels (of intermediate and small conductance, respectively), the group of voltage-gated (Kv) channels including their Beta (or Kv ancilliary) subunits, two-pore K(2P) channels, as well as inwardly rectifying K(+) (Kir) channels (also contributing to K(ATP) channels). In some cells, hypotonicity activates non-selective cation channels. This is surprising, at first sight, because of the inside negative membrane voltage and the sum of driving forces for Na(+) and K(+) diffusion across the cell membrane rather favouring net cation uptake. Some of these channels, however, exhibit a P(K)/P(Na) significantly higher than 1, whereas others are Ca(++) permeable linking hypotonic stress to the activation of Ca(++) dependent ion channels. In particular, the latter holds for the group of TRPs which are specialised in the

  3. [Antioxidant activity of cationic whey protein isolate].

    Science.gov (United States)

    titova, M E; Komolov, S A; Tikhomirova, N A

    2012-01-01

    The process of lipid peroxidation (LPO) in biological membranes of cells is carried out by free radical mechanism, a feature of which is the interaction of radicals with other molecules. In this work we investigated the antioxidant activity of cationic whey protein isolate, obtained by the cation-exchange chromatography on KM-cellulose from raw cow's milk, in vitro and in vivo. In biological liquids, which are milk, blood serum, fetal fluids, contains a complex of biologically active substances with a unique multifunctional properties, and which are carrying out a protective, antimicrobial, regenerating, antioxidant, immunomodulatory, regulatory and others functions. Contents of the isolate were determined electrophoretically and by its biological activity. Cationic whey protein isolate included lactoperoxidase, lactoferrin, pancreatic RNase, lysozyme and angeogenin. The given isolate significantly has an antioxidant effect in model experimental systems in vitro and therefore may be considered as a factor that can adjust the intensity of lipid oxidation. In model solutions products of lipid oxidation were obtained by oxidation of phosphatidylcholine by hydrogen peroxide in the presence of a source of iron. The composition of the reaction mixture: 0,4 mM H2O2; 50 mcM of hemin; 2 mg/ml L-alpha-phosphatidylcholine from soybean (Sigma, German). Lipid peroxidation products were formed during the incubation of the reaction mixture for two hours at 37 degrees C. In our studies rats in the adaptation period immediately after isolation from the nest obtained from food given orally native cationic whey protein isolate at the concentration three times higher than in fresh cow's milk. On the manifestation of the antioxidant activity of cationic whey protein isolate in vivo evidence decrease of lipid peroxidation products concentration in the blood of rats from the experimental group receipt whey protein isolate in dos 0,6 mg/g for more than 20% (pwhey protein isolate has an

  4. Alkali cation specific adsorption onto fcc(111) transition metal electrodes.

    Science.gov (United States)

    Mills, J N; McCrum, I T; Janik, M J

    2014-07-21

    The presence of alkali cations in electrolyte solutions is known to impact the rate of electrocatalytic reactions, though the mechanism of such impact is not conclusively determined. We use density functional theory (DFT) to examine the specific adsorption of alkali cations to fcc(111) electrode surfaces, as specific adsorption may block catalyst sites or otherwise impact surface catalytic chemistry. Solvation of the cation-metal surface structure was investigated using explicit water models. Computed equilibrium potentials for alkali cation adsorption suggest that alkali and alkaline earth cations will specifically adsorb onto Pt(111) and Pd(111) surfaces in the potential range of hydrogen oxidation and hydrogen evolution catalysis in alkaline solutions.

  5. Interaction between alginates and manganese cations: identification of preferred cation binding sites.

    Science.gov (United States)

    Emmerichs, N; Wingender, J; Flemming, H-C; Mayer, C

    2004-04-01

    Algal and bacterial alginates have been studied by means of 13C NMR spectroscopy in presence of paramagnetic manganese ions in order to reveal the nature of their interaction with bivalent cations. It is found that the mannuronate blocks bind manganese cations externally near their carboxylate groups, while guluronate blocks show the capability to integrate Mn2+ into pocket-like structures formed by adjacent guluronate residues. In alternating mannuronate-guluronate blocks, manganese ions preferentially locate in a concave structure formed by guluronate-mannuronate pairs. Partial acetylation of the alginate generally reduces its capability to interact with bivalent cations, however, the selectivity of the binding geometry is conserved. The results may serve as a hint for the better understanding of the alginate gelation in presence of calcium ions.

  6. 斜带石斑鱼胰蛋白酶原和淀粉酶全长cDNA的克隆与序列分析%Molecular cloning and sequence analysis of pancreatic trypsinogen and amylase from orange-spotted grouper(Epinephelus coioides)

    Institute of Scientific and Technical Information of China (English)

    胡永乐; 梁旭方; 王琳; 李观贵; 刘秀霞; 王云新; 张海发

    2010-01-01

    采用RT-PCR及RACE法从斜带石斑鱼Epinephelus coioides肝胰脏克隆得到胰蛋白酶原(trypsinogen,TRY)与淀粉酶(amylase,AMY)基因cDNA全序列.斜带石斑鱼肝胰脏TRY基因cDNA全长911 bp,其中5非翻译区(5'-UTR)为55bp,3'-UTR为127bp,开放阅读框(ORF)为729bp,编码242个氨基酸,包含所有丝氨酸蛋白酶中共有的高度保守的催化活性中心.序列一致性分析发现,斜带石斑鱼与牙鲆Paralichthys olivaceus、金头鲷Sparus aurata、鳎Solea senegalensis、石鲽Pleuronectes bicoloratus的TRY序列相似性高达86.8%-89.70%,与人Homo sapiens小鼠Mus musculus、斑马鱼Danio rerio的TRY相似性较低为59.9%-64.5%.斜带石斑鱼AMY基因cDNA全长1657bp,其中5'-UTR为41bp,3'-UTR为77 bp,ORF为1539bp,编码512个氨基酸,包含与哺乳动物α-AMY二级结构相似的8个α旋和8个β折叠.序列一致性分析发现,斜带石斑鱼与澳洲肺鱼Neoceratodus forsteri、美洲拟鲽Limanda americanus、大西洋鲑Salmo salar、斑马鱼AMY基因序列相似性高达82.4%-91.8%,与人、小鼠、鸡G.Gallus的AMY基因相似性较低为70.1%-72.3%.斜带石斑鱼TRY和AMY基因cDNA全序列的成功克隆为进一步研究其表达调控机理及研发有效提高其表达水平的饲料添加剂奠定基础.

  7. Aggregate Formed by a Cationic Fluorescence Probe

    Institute of Scientific and Technical Information of China (English)

    TIAN, Juan; SANG, Da-Yong; JI, Guo-Zhen

    2007-01-01

    The aggregation behavior of a cationic fluorescence probe 10-(4,7,10,13,16-pentaoxa-1-azacyclooctadecyl-methyl)anthracen-9-ylmethyl dodecanoate (1) was observed and studied by a fluorescence methodology in acidic and neutral conditions. By using the Py scale, differences between simple aggregates and micelles have been discussed. The stability of simple aggregates was discussed in terms of hydrophobic interaction and electrostatic repulsion. The absence of excimer emission of the anthrancene moiety of probe 1 in neutral condition was attributed to the photoinduced electron transfer mechanism instead of photodimerization.

  8. Complex Macromolecular Architectures by Living Cationic Polymerization

    KAUST Repository

    Alghamdi, Reem D.

    2015-05-01

    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  9. Heart imaging with cationic complexes of technetium

    Energy Technology Data Exchange (ETDEWEB)

    Deutsch, E.; Bushong, W.; Glavan, K.A.; Elder, R.C.; Sodd, V.J.; Scholz, K.L.; Fortman, D.L.; Lukes, S.J.

    1981-10-02

    The cationic technetium-99 complex trans-(99TC(dmpe)2Cl2)+, where dmpe is bis(1,2-dimethylphosphino)ethane or (CH3)2P-CH2-P(CH3)2, has been prepared and characterized by single-crystal, x-ray structural analysis. The technetium-99m analog, trans-(99mTc(dmpe) 2Cl2)+, has also been prepared and shown to yield excellent gamma-ray images of the heart. The purposeful design, characterization, and synthesis of this technetium-99m radiopharmaceutical represents a striking application of fundamental inorganic chemistry to a problem in applied nuclear medicine.

  10. Antibacterial Activity of Geminized Amphiphilic Cationic Homopolymers.

    Science.gov (United States)

    Wang, Hui; Shi, Xuefeng; Yu, Danfeng; Zhang, Jian; Yang, Guang; Cui, Yingxian; Sun, Keji; Wang, Jinben; Yan, Haike

    2015-12-22

    The current study is aimed at investigating the effect of cationic charge density and hydrophobicity on the antibacterial and hemolytic activities. Two kinds of cationic surfmers, containing single or double hydrophobic tails (octyl chains or benzyl groups), and the corresponding homopolymers were synthesized. The antimicrobial activity of these candidate antibacterials was studied by microbial growth inhibition assays against Escherichia coli, and hemolysis activity was carried out using human red blood cells. It was interestingly found that the homopolymers were much more effective in antibacterial property than their corresponding monomers. Furthermore, the geminized homopolymers had significantly higher antibacterial activity than that of their counterparts but with single amphiphilic side chains in each repeated unit. Geminized homopolymers, with high positive charge density and moderate hydrophobicity (such as benzyl groups), combine both advantages of efficient antibacterial property and prominently high selectivity. To further explain the antibacterial performance of the novel polymer series, the molecular interaction mechanism is proposed according to experimental data which shows that these specimens are likely to kill microbes by disrupting bacterial membranes, leading them unlikely to induce resistance.

  11. Photodissociation of Cerium Oxide Nanocluster Cations.

    Science.gov (United States)

    Akin, S T; Ard, S G; Dye, B E; Schaefer, H F; Duncan, M A

    2016-04-21

    Cerium oxide cluster cations, CexOy(+), are produced via laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. The mass spectrum displays a strongly preferred oxide stoichiometry for each cluster with a specific number of metal atoms x, with x ≤ y. Specifically, the most prominent clusters correspond to the formula CeO(CeO2)n(+). The cluster cations are mass selected and photodissociated with a Nd:YAG laser at either 532 or 355 nm. The prominent clusters dissociate to produce smaller species also having a similar CeO(CeO2)n(+) formula, always with apparent leaving groups of (CeO2). The production of CeO(CeO2)n(+) from the dissociation of many cluster sizes establishes the relative stability of these clusters. Furthermore, the consistent loss of neutral CeO2 shows that the smallest neutral clusters adopt the same oxidation state (IV) as the most common form of bulk cerium oxide. Clusters with higher oxygen content than the CeO(CeO2)n(+) masses are present with much lower abundance. These species dissociate by the loss of O2, leaving surviving clusters with the CeO(CeO2)n(+) formula. Density functional theory calculations on these clusters suggest structures composed of stable CeO(CeO2)n(+) cores with excess oxygen bound to the surface as a superoxide unit (O2(-)).

  12. Electronic absorptions of the benzylium cation

    Science.gov (United States)

    Dryza, Viktoras; Chalyavi, Nahid; Sanelli, Julian A.; Bieske, Evan J.

    2012-11-01

    The electronic transitions of the benzylium cation (Bz+) are investigated over the 250-550 nm range by monitoring the photodissociation of mass-selected C7H7+-Arn (n = 1, 2) complexes in a tandem mass spectrometer. The Bz+-Ar spectrum displays two distinct band systems, the S1←S0 band system extending from 370 to 530 nm with an origin at 19 067 ± 15 cm-1, and a much stronger S3←S0 band system extending from 270 to 320 nm with an origin at 32 035 ± 15 cm-1. Whereas the S1←S0 absorption exhibits well resolved vibrational progressions, the S3←S0 absorption is broad and relatively structureless. Vibronic structure of the S1←S0 system, which is interpreted with the aid of time-dependent density functional theory and Franck-Condon simulations, reflects the activity of four totally symmetric ring deformation modes (ν5, ν6, ν9, ν13). We find no evidence for the ultraviolet absorption of the tropylium cation, which according to the neon matrix spectrum should occur over the 260 - 275 nm range [A. Nagy, J. Fulara, I. Garkusha, and J. Maier, Angew. Chem., Int. Ed. 50, 3022 (2011)], 10.1002/anie.201008036.

  13. Transition-Metal Hydride Radical Cations.

    Science.gov (United States)

    Hu, Yue; Shaw, Anthony P; Estes, Deven P; Norton, Jack R

    2016-08-10

    Transition-metal hydride radical cations (TMHRCs) are involved in a variety of chemical and biochemical reactions, making a more thorough understanding of their properties essential for explaining observed reactivity and for the eventual development of new applications. Generally, these species may be treated as the ones formed by one-electron oxidation of diamagnetic analogues that are neutral or cationic. Despite the importance of TMHRCs, the generally sensitive nature of these complexes has hindered their development. However, over the last four decades, many more TMHRCs have been synthesized, characterized, isolated, or hypothesized as reaction intermediates. This comprehensive review focuses on experimental studies of TMHRCs reported through the year 2014, with an emphasis on isolated and observed species. The methods used for the generation or synthesis of TMHRCs are surveyed, followed by a discussion about the stability of these complexes. The fundamental properties of TMHRCs, especially those pertaining to the M-H bond, are described, followed by a detailed treatment of decomposition pathways. Finally, reactions involving TMHRCs as intermediates are described.

  14. Cationic Antimicrobial Polymers and Their Assemblies

    Directory of Open Access Journals (Sweden)

    Ana Maria Carmona-Ribeiro

    2013-05-01

    Full Text Available Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs. The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications.

  15. Nature as a source of inspiration for cationic lipid synthesis.

    Science.gov (United States)

    Labas, Romain; Beilvert, Fanny; Barteau, Benoit; David, Stéphanie; Chèvre, Raphaël; Pitard, Bruno

    2010-02-01

    Synthetic gene delivery systems represent an attractive alternative to viral vectors for DNA transfection. Cationic lipids are one of the most widely used non-viral vectors for the delivery of DNA into cultured cells and are easily synthesized, leading to a large variety of well-characterized molecules. This review discusses strategies for the design of efficient cationic lipids that overcome the critical barriers of in vitro transfection. A particular focus is placed on natural hydrophilic headgroups and lipophilic tails that have been used to synthesize biocompatible and non-toxic cationic lipids. We also present chemical features that have been investigated to enhance the transfection efficiency of cationic lipids by promoting the escape of lipoplexes from the endosomal compartment and DNA release from DNA-liposome complexes. Transfection efficiency studies using these strategies are likely to improve the understanding of the mechanism of cationic lipid-mediated gene delivery and to help the rational design of novel cationic lipids.

  16. Cation-π interaction of the univalent silver cation with meso-octamethylcalix[4]pyrrole: Experimental and theoretical study

    Science.gov (United States)

    Polášek, Miroslav; Kvíčala, Jaroslav; Makrlík, Emanuel; Křížová, Věra; Vaňura, Petr

    2017-02-01

    By using electrospray ionization mass spectrometry (ESI-MS), it was proven experimentally that the univalent silver cation Ag+ forms with meso-octamethylcalix[4]pyrrole (abbrev. 1) the cationic complex species 1·Ag+. Further, applying quantum chemical DFT calculations, four different conformations of the resulting complex 1·Ag+ were derived. It means that under the present experimental conditions, this ligand 1 can be considered as a macrocyclic receptor for the silver cation.

  17. Capturing dynamic cation hopping in cubic pyrochlores

    Science.gov (United States)

    Brooks Hinojosa, Beverly; Asthagiri, Aravind; Nino, Juan C.

    2011-08-01

    In direct contrast to recent reports, density functional theory predicts that the most stable structure of Bi2Ti2O7 pyrochlore is a cubic Fd3¯m space group by accounting for atomic displacements. The displaced Bi occupies the 96g(x,x,z) Wyckoff position with six equivalent sites, which create multiple local minima. Using nudged elastic band method, the transition states of Bi cation hopping between equivalent minima were investigated and an energy barrier between 0.11 and 0.21 eV was determined. Energy barriers associated with the motion of Bi between equivalent sites within the 96g Wyckoff position suggest the presence of dielectric relaxation in Bi2Ti2O7.

  18. Retention of Cationic Starch onto Cellulose Fibres

    Science.gov (United States)

    Missaoui, Mohamed; Mauret, Evelyne; Belgacem, Mohamed Naceur

    2008-08-01

    Three methods of cationic starch titration were used to quantify its retention on cellulose fibres, namely: (i) the complexation of CS with iodine and measurement of the absorbency of the ensuing blue solution by UV-vis spectroscopy; (ii) hydrolysis of the starch macromolecules followed by the conversion of the resulting sugars to furan-based molecules and quantifying the ensuing mixture by measuring their absorbance at a Ι of 490 nm, using the same technique as previous one and; finally (iii) hydrolysis of starch macromolecules by trifluoro-acetic acid and quantification of the sugars in the resulting hydrolysates by high performance liquid chromatography. The three methods were found to give similar results within the range of CS addition from 0 to 50 mg per g of cellulose fibres.

  19. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment

    DEFF Research Database (Denmark)

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C.;

    2016-01-01

    Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD) library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We...... then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients...... with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any...

  20. Heart imaging with cationic complexes of technetium

    Energy Technology Data Exchange (ETDEWEB)

    Deutsch, E. (Univ. of Cincinnati, Cincinnati, OH); Bushong, W.; Glavan, K.A.; Elder, R.C.; Sodd, V.J.; Scholz, K.L.; Fortman, D.L.; Lukes, S.J.

    1981-10-02

    The cationic technetium-99 complex trans-(/sup 99/Tc(dmpe)/sub 2/Cl/sub 2/)/sup +/, where dmpe is bis(1,2-dimethylphosphino)ethane or (CH/sub 3/)/sub 2/P-CH/sub 2/CH/sub 2/-P(CH/sub 3/)/sub 2/, has been prepared and characterized by single-crystal, x-ray structural analysis. The technetium-99m analog, trans-(/sup 99m/Tc (dmpe)/sub 2/Cl/sub 2/)/sup +/, has also been prepared and shown to yield excellent gamma-ray images of the heart. The purposeful design, characterization, and synthesis of this technetium-99m radiopharmaceutical represents a striking application of fundamental inorganic chemistry to a problem in applied nuclear medicine.

  1. Electron spectra of radical cations of heteroanalogs

    Energy Technology Data Exchange (ETDEWEB)

    Petrushenko, K.B.; Turchaninov, V.K.; Vokin, A.I.; Ermikov, A.F.; Frolov, Yu.L.

    1985-12-01

    Radical cation spectra of indazole and benzothiophene in the visible region were obtained by laser photolysis during the reaction of photoexcited quinones with these compounds in acetonitrile. The charge transfer bands of the complexes of the test compounds with p-chloranil and 7,7,8,8-tetracyanoquinodimethane in dioxane were recorded on a Specord M-40. Photoelectron spectra were obtained on a ES-3201 electron spectrometer. The He(I) resonance band (21.21 eV) was used for excitation. Measurements were carried out in the 60-120/sup 0/C range. The energy scale was calibrated form the first ionization potentials of Ar (15.76 eV) and chlorobenzene (9.06 eV). The error in the determination of the ionization potentials for the first four photoelectron bands was 0.05 eV.

  2. Hydration Structure of the Quaternary Ammonium Cations

    KAUST Repository

    Babiaczyk, Wojtek Iwo

    2010-11-25

    Two indicators of the hydropathicity of small solutes are introduced and tested by molecular dynamics simulations. These indicators are defined as probabilities of the orientation of water molecules\\' dipoles and hydrogen bond vectors, conditional on a generalized distance from the solute suitable for arbitrarily shaped molecules. Using conditional probabilities, it is possible to distinguish features of the distributions in close proximity of the solute. These regions contain the most significant information on the hydration structure but cannot be adequately represented by using, as is usually done, joint distance-angle probability densities. Our calculations show that using our indicators a relative hydropathicity scale for the interesting test set of the quaternary ammonium cations can be roughly determined. © 2010 American Chemical Society.

  3. Antiviral effect of cationic compounds on bacteriophages

    Directory of Open Access Journals (Sweden)

    Mai Huong eChatain-Ly

    2013-03-01

    Full Text Available The antiviral activity of several cationic compounds - cetytrimethylammonium (CTAB, chitosan, nisin and lysozyme - was investigated on the bacteriophage c2 (DNA head and non-contractile tail infecting Lactococcus strains and the bacteriophage MS2 (F-specific RNA infecting E.coli. Firstly, these activities were evaluated in a phosphate buffer pH 7- 10 mM. The CTAB had a virucidal effect on the Lactococcus bacteriophages, but not on the MS2. After 1 min of contact with 0.125 mM CTAB, the c2 population was reduced from 6 log(pfu/mL to 1,5 log(pfu/mL and completely deactivated at 1 mM. On the contrary, chitosan inhibited the MS2 more than it did the bacteriophages c2. No antiviral effect was observed for the nisin or the lysozyme on bacteriophages after 1 min of treatment. A 1 and 2.5 log reduction was respectively observed for nisin and lysozyme when the treatment time increased (5 or 10 min. These results showed that the antiviral effect depended both on the virus and structure of the antimicrobial compounds. The antiviral activity of these compounds was also evaluated in different physico-chemical conditions and in complex matrices. The antiviral activity of CTAB was impaired in acid pH and with an increase of the ionic strength. These results might be explained by the electrostatic interactions between cationic compounds and negatively charged particles such as bacteriophages or other compounds in a matrix. Milk proved to be protective suggesting the components of food could interfere with antimicrobial compounds.

  4. Role of extracellular cations in cell motility, polarity, and chemotaxis

    Directory of Open Access Journals (Sweden)

    Soll D

    2011-04-01

    Full Text Available David R Soll1, Deborah Wessels1, Daniel F Lusche1, Spencer Kuhl1, Amanda Scherer1, Shawna Grimm1,21Monoclonal Antibody Research Institute, Developmental Studies, Hybridoma Bank, Department of Biology, University of Iowa, Iowa City; 2Mercy Medical Center, Surgical Residency Program, Des Moines, Iowa, USAAbstract: The concentration of cations in the aqueous environment of free living organisms and cells within the human body influence motility, shape, and chemotaxis. The role of extracellular cations is usually perceived to be the source for intracellular cations in the process of homeostasis. The role of surface molecules that interact with extracellular cations is believed to be that of channels, transporters, and exchangers. However, the role of Ca2+ as a signal and chemoattractant and the discovery of the Ca2+ receptor have demonstrated that extracellular cations can function as signals at the cell surface, and the plasma membrane molecules they interact with can function as bona fide receptors that activate coupled signal transduction pathways, associated molecules in the plasma membrane, or the cytoskeleton. With this perspective in mind, we have reviewed the cationic composition of aqueous environments of free living cells and cells that move in multicellular organisms, most notably humans, the range of molecules interacting with cations at the cell surface, the concept of a cell surface cation receptor, and the roles extracellular cations and plasma membrane proteins that interact with them play in the regulation of motility, shape, and chemotaxis. Hopefully, the perspective of this review will increase awareness of the roles extracellular cations play and the possibility that many of the plasma membrane proteins that interact with them could also play roles as receptors.Keywords: extracellular cations, chemotaxis, transporters, calcium, receptors

  5. The Effect of Hydration on the Cation-π Interaction Between Benzene and Various Cations

    Indian Academy of Sciences (India)

    VIKASH DHINDHWAL; N SATHYAMURTHY

    2016-10-01

    The effect of hydration on cation-π interaction in Mq+ BmWn (B = benzene; W = water; Mq+ =Na⁺, K⁺, Mg²⁺, Ca²⁺, Al³⁺, 0 ≤ n,m ≤ 4, 1≤ m + n ≤ 4) complexes has been investigated using ab initio quantum chemical methods. Interaction energy values computed at the MP2 level of theory using the 6-31G(d,p) basis set reveal a qualitative trend in the relative affinity of different cations for benzene and water in these complexes. The π–cloud thickness values for benzene have also been estimated for these systems.

  6. In vivo toxicity of cationic micelles and liposomes

    DEFF Research Database (Denmark)

    Knudsen, Kristina Bram; Northeved, Helle; Ek, Pramod Kumar

    2015-01-01

    This study investigated toxicity of nanocarriers comprised of cationic polymer and lipid components often used in gene and drug delivery, formulated as cationic micelles and liposomes. Rats were injected intravenously with 10, 25 or 100 mg/kg and sacrificed after 24 or 48 h, or 24 h after the last...

  7. How mobile are sorbed cations in clays and clay rocks?

    Science.gov (United States)

    Gimmi, T; Kosakowski, G

    2011-02-15

    Diffusion of cations and other contaminants through clays is of central interest, because clays and clay rocks are widely considered as barrier materials for waste disposal sites. An intriguing experimental observation has been made in this context: Often, the diffusive flux of cations at trace concentrations is much larger and the retardation smaller than expected based on their sorption coefficients. So-called surface diffusion of sorbed cations has been invoked to explain the observations but remains a controversial issue. Moreover, the corresponding surface diffusion coefficients are largely unknown. Here we show that, by an appropriate scaling, published diffusion data covering a broad range of cations, clays, and chemical conditions can all be modeled satisfactorily by a surface diffusion model. The average mobility of sorbed cations seems to be primarily an intrinsic property of each cation that follows inversely its sorption affinity. With these surface mobilities, cation diffusion coefficients can now be estimated from those of water tracers. In pure clays at low salinities, surface diffusion can reduce the cation retardation by a factor of more than 1000.

  8. Interactions between cationic liposomes and drugs or biomolecules

    Directory of Open Access Journals (Sweden)

    ANA MARIA CARMONA-RIBEIRO

    2000-03-01

    Full Text Available Multiple uses for synthetic cationic liposomes composed of dioctadecyldimethylammonium bromide (DODAB bilayer vesicles are presented. Drugs or biomolecules can be solubilized or incorporated in the cationic bilayers. The cationic liposomes themselves can act as antimicrobial agents causing death of bacteria and fungi at concentrations that barely affect mammalian cells in culture. Silica particles or polystyrene microspheres can be functionalized by coverage with DODAB bilayers or phospholipid monolayers. Negatively charged antigenic proteins can be carried by the cationic liposomes which generate a remarkable immunoadjuvant action. Nucleotides or DNA can be physically adsorbed to the cationic liposomes to be transferred to mammalian cells for gene therapy. An overview of the interactions between DODAB vesicles and some biomolecules or drugs clearly points out their versatility for useful applications in a near future.

  9. Interactions between cationic liposomes and drugs or biomolecules.

    Science.gov (United States)

    Carmona-Ribeiro, A M

    2000-01-01

    Multiple uses for synthetic cationic liposomes composed of dioctadecyldimethylammonium bromide (DODAB) bilayer vesicles are presented. Drugs or biomolecules can be solubilized or incorporated in the cationic bilayers. The cationic liposomes themselves can act as antimicrobial agents causing death of bacteria and fungi at concentrations that barely affect mammalian cells in culture. Silica particles or polystyrene microspheres can be functionalized by coverage with DODAB bilayers or phospholipid monolayers. Negatively charged antigenic proteins can be carried by the cationic liposomes which generate a remarkable immunoadjuvant action. Nucleotides or DNA can be physically adsorbed to the cationic liposomes to be transferred to mammalian cells for gene therapy. An overview of the interactions between DODAB vesicles and some biomolecules or drugs clearly points out their versatility for useful applications in a near future.

  10. Do Cation-π Interactions Exist in Bacteriorhodopsin

    Institute of Scientific and Technical Information of China (English)

    HU Kun-Sheng; WANG Guang-Yu; HE Jin-An

    2001-01-01

    Metal ions are essential to the structure and physiological functions of bacteriorhodopsin. Experimental evidence suggests the existence of specific cation binding to the negatively charged groups of Asp85 and Asp212 via an electrostatic interaction. However, only using electrostatic force is not enough to explain the role of the metal cations because the carboxylate of Asp85 is well known to be protonated in the M intermediate. Considering the presence of some aromatic amino acid residues in the vicinity of the retinal pocket, the existence of cation-π interactions between the metal cation and aromatic amino acid residues is suggested. Obviously, introduction of this kind of interaction is conducive to understanding the effects of the metal cations and aromatic amino acid residues inside the protein on the structural stability and proton pumping of bacteriorhodopsin.

  11. Trypsinogen activation as observed in accelerated molecular dynamics simulations.

    Science.gov (United States)

    Boechi, Leonardo; Pierce, Levi; Komives, Elizabeth A; McCammon, J Andrew

    2014-11-01

    Serine proteases are involved in many fundamental physiological processes, and control of their activity mainly results from the fact that they are synthetized in an inactive form that becomes active upon cleavage. Three decades ago Martin Karplus's group performed the first molecular dynamics simulations of trypsin, the most studied member of the serine protease family, to address the transition from the zymogen to its active form. Based on the computational power available at the time, only high frequency fluctuations, but not the transition steps, could be observed. By performing accelerated molecular dynamics (aMD) simulations, an interesting approach that increases the configurational sampling of atomistic simulations, we were able to observe the N-terminal tail insertion, a crucial step of the transition mechanism. Our results also support the hypothesis that the hydrophobic effect is the main force guiding the insertion step, although substantial enthalpic contributions are important in the activation mechanism. As the N-terminal tail insertion is a conserved step in the activation of serine proteases, these results afford new perspective on the underlying thermodynamics of the transition from the zymogen to the active enzyme.

  12. Anaerobic toxicity of cationic silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gitipour, Alireza; Thiel, Stephen W. [Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, Cincinnati, OH (United States); Scheckel, Kirk G. [USEPA, Office of Research and Development, Cincinnati, OH (United States); Tolaymat, Thabet, E-mail: tolaymat.thabet@epa.gov [USEPA, Office of Research and Development, Cincinnati, OH (United States)

    2016-07-01

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag{sup +} under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged polyvinylpyrrolidone coated AgNPs (PVP-AgNPs) and (3) positively charged branched polyethyleneimine coated AgNPs (BPEI-AgNPs). The AgNPs investigated in this experiment were similar in size (10–15 nm), spherical in shape, but varied in surface charge which ranged from highly negative to highly positive. While, at AgNPs concentrations lower than 5 mg L{sup −1}, the anaerobic decomposition process was not influenced by the presence of the nanoparticles, there was an observed impact on the diversity of the microbial community. At elevated concentrations (100 mg L{sup −1} as silver), only the cationic BPEI-AgNPs demonstrated toxicity similar in magnitude to that of Ag{sup +}. Both citrate and PVP-AgNPs did not exhibit toxicity at the 100 mg L{sup −1} as measured by biogas evolution. These findings further indicate the varying modes of action for nanoparticle toxicity and represent one of the few studies that evaluate end-of-life management concerns with regards to the increasing use of nanomaterials in our everyday life. These findings also highlight some of the concerns with a one size fits all approach to the evaluation of environmental health and safety concerns associated with the use of nanoparticles. - Highlights: • At concentrations -1 the anaerobic decomposition process was not impacted. • An impact on the microbial community at concentrations -1 were observed. • At high concentrations (100 mg L{sup −1}), the cationic BPEI-AgNPs demonstrated toxicity. • Toxicity was demonstrated without the presence of oxidative dissolution of silver. • A one size fits all approach for the evaluation of NPs may not be accurate.

  13. IRMPD Action Spectroscopy of Alkali Metal Cation-Cytosine Complexes: Effects of Alkali Metal Cation Size on Gas Phase Conformation

    NARCIS (Netherlands)

    Yang, B.; Wu, R.R.; Polfer, N.C.; Berden, G.; Oomens, J.; Rodgers, M.T.

    2013-01-01

    The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra of five alkali metal cation-cytosine complexes exhibit both simi

  14. Cation Defects and Conductivity in Transparent Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Exarhos, Gregory J.; Windisch, Charles F.; Ferris, Kim F.; Owings, Robert R.

    2007-10-24

    High quality doped zinc oxide and mixed transition metal spinel oxide films have been deposited by means of sputter deposition from metal and metal oxide targets, and by spin casting from aqueous or alcoholic precursor solutions. Deposition conditions and post-deposition processing are found to alter cation oxidation states and their distributions in both oxide materials resulting in marked changes to both optical transmission and electrical response. For ZnO, partial reduction of the neat or doped material by hydrogen treatment of the heated film or by electrochemical processing renders the oxide n-type conducting. Continued reduction was found to diminish conductivity. In contrast, oxidation of the infrared transparent p-type spinel conductors typified by NiCo2O4 was found to increase conductivity. The disparate behavior of these two materials is caused in part by the sign of the charge carrier and by the existence of two different charge transport mechanisms that are identified as free carrier conduction and polaron hopping. While much work has been reported concerning structure/property relationships in the free carrier conducting oxides, there is a significantly smaller body of information on transparent polaron conductors. In this paper, we identify key parameters that promote conductivity in mixed metal spinel oxides and compare their behavior with that of the free carrier TCO’s.

  15. INTERACTIONS BETWEEN CATIONIC POLYELECTROLYTE AND PULP FINES

    Directory of Open Access Journals (Sweden)

    Elina Orblin

    2011-05-01

    Full Text Available Papermaking pulps are a mixture of fibres, fibre fragments, and small cells (parenchyma or ray cells, usually called pulp fines. The interactions between pulp fines and a cationic copolymer of acrylamide and acryloxyethyltrimethyl ammonium chloride were investigated based on solid-liquid isotherms prepared under different turbulence, and subsequent advanced surface characterization using X-ray photoelectron spectroscopy (XPS and time-of-flight secondary ion mass spectrometry (ToF-SIMS. The surface charge and surface area of pulp fine substrates were measured by methylene blue sorption-XPS analysis and nitrogen adsorption combined with mercury porosimetry, respectively. The driving force behind polyelectrolyte adsorption was the amount of the surface anionic charge, whereas surface area appeared to be of less importance. Based on a comparison of solid-liquid and XPS sorption isotherms, different polyelectrolyte conformations were suggested, depending on the types of fines: A flatter conformation and partial cell-wall penetration of polyelectrolytes on kraft fines from freshly prepared pulp, and a more free conformation with extended loops and tails on lignocellulosic fines from recycled pulp. Additionally, ToF-SIMS imaging proved that recycled pulp fines contained residual de-inking chemicals (primarily palmitic acid salts that possibly hinder the electrostatic interactions with polyelectrolytes.

  16. Cationic Noncovalent Interactions: Energetics and Periodic Trends.

    Science.gov (United States)

    Rodgers, M T; Armentrout, P B

    2016-05-11

    In this review, noncovalent interactions of ions with neutral molecules are discussed. After defining the scope of the article, which excludes anionic and most protonated systems, methods associated with measuring thermodynamic information for such systems are briefly recounted. An extensive set of tables detailing available thermodynamic information for the noncovalent interactions of metal cations with a host of ligands is provided. Ligands include small molecules (H2, NH3, CO, CS, H2O, CH3CN, and others), organic ligands (O- and N-donors, crown ethers and related molecules, MALDI matrix molecules), π-ligands (alkenes, alkynes, benzene, and substituted benzenes), miscellaneous inorganic ligands, and biological systems (amino acids, peptides, sugars, nucleobases, nucleosides, and nucleotides). Hydration of metalated biological systems is also included along with selected proton-based systems: 18-crown-6 polyether with protonated peptides and base-pairing energies of nucleobases. In all cases, the literature thermochemistry is evaluated and, in many cases, reanchored or adjusted to 0 K bond dissociation energies. Trends in these values are discussed and related to a variety of simple molecular concepts.

  17. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment

    Directory of Open Access Journals (Sweden)

    Anne-Marie Ellegaard

    2016-07-01

    Full Text Available Non-small cell lung cancer (NSCLC is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any non-localized cancer, and ebastine use showed a similar tendency. The association between CAD antihistamine use and reduced mortality was stronger among patients with records of concurrent chemotherapy than among those without such records. In line with this, sub-micromolar concentrations of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy.

  18. Cation exchange properties of zeolites in hyper alkaline aqueous media.

    Science.gov (United States)

    Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

    2015-02-03

    Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media.

  19. Lipopolysaccharide Neutralization by Cationic-Amphiphilic Polymers through Pseudoaggregate Formation.

    Science.gov (United States)

    Uppu, Divakara S S M; Haldar, Jayanta

    2016-03-14

    Synthetic polymers incorporating the cationic charge and hydrophobicity to mimic the function of antimicrobial peptides (AMPs) have been developed. These cationic-amphiphilic polymers bind to bacterial membranes that generally contain negatively charged phospholipids and cause membrane disintegration resulting in cell death; however, cationic-amphiphilic antibacterial polymers with endotoxin neutralization properties, to the best of our knowledge, have not been reported. Bacterial endotoxins such as lipopolysaccharide (LPS) cause sepsis that is responsible for a great amount of mortality worldwide. These cationic-amphiphilic polymers can also bind to negatively charged and hydrophobic LPS and cause detoxification. Hence, we envisaged that cationic-amphiphilic polymers can have both antibacterial as well as LPS binding properties. Here we report synthetic amphiphilic polymers with both antibacterial as well as endotoxin neutralizing properties. Levels of proinflammatory cytokines in human monocytes caused by LPS stimulation were inhibited by >80% when coincubated with these polymers. These reductions were found to be dependent on concentration and, more importantly, on the side-chain chemical structure due to variations in the hydrophobicity profiles of these polymers. These cationic-amphiphilic polymers bind and cause LPS neutralization and detoxification. Investigations of polymer interaction with LPS using fluorescence spectroscopy and dynamic light scattering (DLS) showed that these polymers bind but neither dissociate nor promote LPS aggregation. We show that polymer binding to LPS leads to sort of a pseudoaggregate formation resulting in LPS neutralization/detoxification. These findings provide an unusual mechanism of LPS neutralization using novel synthetic cationic-amphiphilic polymers.

  20. Neutron diffraction investigations of kesterites: cation order and disorder

    Energy Technology Data Exchange (ETDEWEB)

    Schorr, Susan [Free University Berlin, Institute of Geological Sciences (Germany); Tovar, Michael [Helmholtz Zentrum Berlin fuer Materialien und Energie (Germany); Levcenco, Sergej; Napetrov, Alexander; Arushanov, Ernest [Academy of Sciences of Moldova Republic, Institute of Applied Physics, Chisinau (Moldova)

    2010-07-01

    The quaternary chalcogenides Cu{sub 2}ZnSnS{sub 4} and Cu{sub 2}ZnSnSe{sub 4} have newly attracted attention as possible absorber materials in thin film solar cells. They crystallize in the kesterite type (space group I anti 4) or stannite type structure (space group I anti 42m), which are described as an ordered distribution of the cations on different structural sites. Cation disorder may cause site defects and hence influences the electronic properties of the material. Thus the degree of cation order/disorder plays a crucial role and was therefor in the focus of the presented investigations. A differentiation between the isoelectronic cations Cu{sup +} and Zn{sup 2+} is not possible using X-ray diffraction due to their similar scattering power. But their neutron scattering lengths are different, thus neutron diffraction opens the possibility to determine the cation distribution in these compounds. A simultaneous Rietveld analysis of neutron and X-ray powder diffraction data revealed that in dependence on the thermal history of the samples cation disorder appears. The correlation trend between cation order/disorder and the sample growth method (solid state synthesis, Bridgman method) are discussed.

  1. Competitive Effects of 2+ and 3+ Cations on DNA Compaction

    CERN Document Server

    Tongu, C; Yoshikawa, Y; Zinchenko, A A; Chen, N; Yoshikawa, K

    2016-01-01

    By using single-DNA observation with fluorescence microscopy, we observed the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA with 166 kbp). It was found that divalent cations, such as Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. These experimental observations are inconsistent with the well-established Debye-Huckel scheme regarding the shielding effect of counter ions, which is given as the additivity of contributions of cations with different valences. We interpreted the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counter ions before and after the folding transition of DNA. For the compaction with SPD(3+), we considered the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly-charged polyelectrolyte, double-st...

  2. Atmospheric CO2 enrichment facilitates cation release from soil.

    Science.gov (United States)

    Cheng, L; Zhu, J; Chen, G; Zheng, X; Oh, N-H; Rufty, T W; Richter, D deB; Hu, S

    2010-03-01

    Atmospheric CO(2) enrichment generally stimulates plant photosynthesis and nutrient uptake, modifying the local and global cycling of bioactive elements. Although nutrient cations affect the long-term productivity and carbon balance of terrestrial ecosystems, little is known about the effect of CO(2) enrichment on cation availability in soil. In this study, we present evidence for a novel mechanism of CO(2)-enhancement of cation release from soil in rice agricultural systems. Elevated CO(2) increased organic C allocation belowground and net H(+) excretion from roots, and stimulated root and microbial respiration, reducing soil redox potential and increasing Fe(2+) and Mn(2+) in soil solutions. Increased H(+), Fe(2+), and Mn(2+) promoted Ca(2+) and Mg(2+) release from soil cation exchange sites. These results indicate that over the short term, elevated CO(2) may stimulate cation release from soil and enhance plant growth. Over the long-term, however, CO(2)-induced cation release may facilitate cation losses and soil acidification, negatively feeding back to the productivity of terrestrial ecosystems.

  3. Cations bind only weakly to amides in aqueous solutions.

    Science.gov (United States)

    Okur, Halil I; Kherb, Jaibir; Cremer, Paul S

    2013-04-01

    We investigated salt interactions with butyramide as a simple mimic of cation interactions with protein backbones. The experiments were performed in aqueous metal chloride solutions using two spectroscopic techniques. In the first, which provided information about contact pair formation, the response of the amide I band to the nature and concentration of salt was monitored in bulk aqueous solutions via attenuated total reflection Fourier transform infrared spectroscopy. It was found that molar concentrations of well-hydrated metal cations (Ca(2+), Mg(2+), Li(+)) led to the rise of a peak assigned to metal cation-bound amides (1645 cm(-1)) and a decrease in the peak associated with purely water-bound amides (1620 cm(-1)). In a complementary set of experiments, the effect of cation identity and concentration was investigated at the air/butyramide/water interface via vibrational sum frequency spectroscopy. In these studies, metal ion-amide binding led to the ordering of the adjacent water layer. Such experiments were sensitive to the interfacial partitioning of cations in either a contact pair with the amide or as a solvent separated pair. In both experiments, the ordering of the interactions of the cations was: Ca(2+) > Mg(2+) > Li(+) > Na(+) ≈ K(+). This is a direct cationic Hofmeister series. Even for Ca(2+), however, the apparent equilibrium dissociation constant of the cation with the amide carbonyl oxygen was no tighter than ∼8.5 M. For Na(+) and K(+), no evidence was found for any binding. As such, the interactions of metal cations with amides are far weaker than the analogous binding of weakly hydrated anions.

  4. Cationic starches on cellulose surfaces. A study of polyelectrolyte adsorption.

    OpenAIRE

    Steeg, van der, P.A.H.

    1992-01-01

    Cationic starches are used on a large scale in paper industry as wet-end additives. They improve dry strength. retention of fines and fillers, and drainage. Closure of the white water systems in the paper mills hase increased the concentration of detrimental substances. This might be the reason for the poor retention of cationic starches observed in the last few years.The purpose of the research described in this thesis was to obtain a better understanding of the adsorption of cationic starch...

  5. Electrostatic charge confinement using bulky tetraoctylammonium cation and four anions

    Science.gov (United States)

    Andreeva, Nadezhda A.; Chaban, Vitaly V.

    2016-04-01

    Thanks to large opposite electrostatic charges, cations and anions establish strong ionic bonds. However, applications of ionic systems - electrolytes, gas capture, solubilization, etc. - benefit from weaker non-covalent bonds. The common approaches are addition of cosolvents and delocalization of electron charge density via functionalization of ions. We report fine tuning of closest-approach distances, effective radii, and cation geometry by different anions using the semi-empirical molecular dynamics simulations. We found that long fatty acid chains employed in the tetraalkylammonium cation are largely inefficient and new substituents must be developed. The reported results foster progress of task-specific ionic liquids.

  6. Competitive Solvation of the Imidazolium Cation by Water and Methanol

    CERN Document Server

    Chaban, Vitaly

    2014-01-01

    Imidazolium-based ionic liquids are widely used in conjunction with molecular liquids for various applications. Solvation, miscibility and similar properties are of fundamental importance for successful implementation of theoretical schemes. This work reports competitive solvation of the 1,3-dimethylimidazolium cation by water and methanol. Employing molecular dynamics simulations powered by semiempirical Hamiltonian (electronic structure level of description), the local structure nearly imidazolium cation is described in terms of radial distribution functions. Although water and methanol are chemically similar, water appears systematically more successful in solvating the 1,3-dimethylimidazolium cation. This result fosters construction of future applications of the ternary ion-molecular systems.

  7. Pyridine radical cation and its fluorine substituted derivatives

    Science.gov (United States)

    Bondybey, V.E.; English, J.H.; Shiley, R.H.

    1982-01-01

    The spectra and relaxation of the pyridine cation and of several of its fluorinated derivatives are studied in low temperature Ne matrices. The ions are generated by direct photoionization of the parent compounds. Of the compounds studied, laser induced → and → fluorescence is observed only for the 2, 6‐difluoropyridine cation. The analysis of the spectrum indicates that the ion is planar both in the and states. The large variety in the spectroscopic and relaxation behavior of fluoropyridine radical cations is explained in terms of their electronic structure and of the differential shifts of the individual electronic states caused by the fluorine substitution.

  8. Novel cationic polyelectrolyte coatings for capillary electrophoresis.

    Science.gov (United States)

    Duša, Filip; Witos, Joanna; Karjalainen, Erno; Viitala, Tapani; Tenhu, Heikki; Wiedmer, Susanne K

    2016-01-01

    The use of bare fused silica capillary in CE can sometimes be inconvenient due to undesirable effects including adsorption of sample or instability of the EOF. This can often be avoided by coating the inner surface of the capillary. In this work, we present and characterize two novel polyelectrolyte coatings (PECs) poly(2-(methacryloyloxy)ethyl trimethylammonium iodide) (PMOTAI) and poly(3-methyl-1-(4-vinylbenzyl)-imidazolium chloride) (PIL-1) for CE. The coated capillaries were studied using a series of aqueous buffers of varying pH, ionic strength, and composition. Our results show that the investigated polyelectrolytes are usable as semi-permanent (physically adsorbed) coatings with at least five runs stability before a short coating regeneration is necessary. Both PECs showed a considerably decreased stability at pH 11.0. The EOF was higher using Good's buffers than with sodium phosphate buffer at the same pH and ionic strength. The thickness of the PEC layers studied by quartz crystal microbalance was 0.83 and 0.52 nm for PMOTAI and PIL-1, respectively. The hydrophobicity of the PEC layers was determined by analysis of a homologous series of alkyl benzoates and expressed as the distribution constants. Our result demonstrates that both PECs had comparable hydrophobicity, which enabled separation of compounds with log Po/w > 2. The ability to separate cationic drugs was shown with β-blockers, compounds often misused in doping. Both coatings were also able to separate hydrolysis products of the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene acetate at highly acidic conditions, where bare fused silica capillaries failed to accomplish the separation.

  9. IRMPD action spectroscopy of alkali metal cation-cytosine complexes: effects of alkali metal cation size on gas phase conformation.

    Science.gov (United States)

    Yang, Bo; Wu, R R; Polfer, N C; Berden, G; Oomens, J; Rodgers, M T

    2013-10-01

    The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra of five alkali metal cation-cytosine complexes exhibit both similar and distinctive spectral features over the range of ~1000-1900 cm(-1). The IRMPD spectra of the Li(+)(cytosine), Na(+)(cytosine), and K(+)(cytosine) complexes are relatively simple but exhibit changes in the shape and shifts in the positions of several bands that correlate with the size of the alkali metal cation. The IRMPD spectra of the Rb(+)(cytosine) and Cs(+)(cytosine) complexes are much richer as distinctive new IR bands are observed, and the positions of several bands continue to shift in relation to the size of the metal cation. The measured IRMPD spectra are compared to linear IR spectra of stable low-energy tautomeric conformations calculated at the B3LYP/def2-TZVPPD level of theory to identify the conformations accessed in the experiments. These comparisons suggest that the evolution in the features in the IRMPD action spectra with the size of the metal cation, and the appearance of new bands for the larger metal cations, are the result of the variations in the intensities at which these complexes can be generated and the strength of the alkali metal cation-cytosine binding interaction, not the presence of multiple tautomeric conformations. Only a single tautomeric conformation is accessed for all five alkali metal cation-cytosine complexes, where the alkali metal cation binds to the O2 and N3 atoms of the canonical amino-oxo tautomer of cytosine, M(+)(C1).

  10. Whole Exome Sequencing Identifies Multiple, Complex Etiologies in an Idiopathic Hereditary Pancreatitis Kindred

    Directory of Open Access Journals (Sweden)

    Jessica LaRusch

    2012-05-01

    Full Text Available Context Hereditary pancreatitis is the early onset form of chronic pancreatitis that is carried in an autosomal dominant pattern with variable penetrance. While 80% of hereditary pancreatitis has been shown to be due to a single mutation in the trypsinogen gene PRSS1, a number of hereditary pancreatitis families have no identified genetic cause for illness; thus no reliable screening options or clear therapy. Objective To explore the use of massive parallel DNA sequencing technology to discover the etiology of pancreatitis in a family with idiopathic hereditary pancreatitis. Design Candidate gene screening and verification within a kindred. Setting Prospective cohort study, university based. Patients or participants Kindred with idiopathic hereditary pancreatitis. Interventions None. Main outcome measures Identification of DNA variants predicted to increase susceptibility to pancreatitis. Methods Whole exome sequencing of two distantly related subjects with variant-specific confirmation in the subjects and other family members. Results We identified three deleterious genetic changes in the three major pancreatitis associated genes (PRSS1 CNV, SPINK1 c.27delC and CFTR R117H, two of which were carried by each patient. Individual targeted assays confirmed these variations in the two whole exome sequencing patients as well as affected and non-affected pedigree members. Conclusion Whole exome sequencing was useful for rapid screening of candidate genes linked to pancreatitis. This method opens the door for time- and cost-effective screening of multiple disease-associated genes and modifying factors that associate in different ways to generate a complex geneticdisorder.

  11. Isomerization of propargyl cation to cyclopropenyl cation: Mechanistic elucidations and effects of lone pair donors

    Indian Academy of Sciences (India)

    Zodinpuia Pachuau; Kiew S Kharnaior; R H Duncan Lyngdoh

    2013-03-01

    This ab initio study examines two pathways (one concerted and the other two-step) for isomerization of the linear propargyl cation to the aromatic cyclopropenyl cation, also probing the phenomenon of solvation of this reaction by simple lone pair donors (NH3, H2O, H2S and HF) which bind to the substrate at two sites. Fully optimized geometries at the B3LYP/6-31G(d) level were used, along with single point QCISD(T)/6-311+G(d,p) and accurate G3 level calculations upon the DFT optimized geometries. For the unsolvated reaction, the two-step second pathway is energetically favoured over the one-step first pathway. Lone pair donor affinity for the various C3H$^{+}_{3}$ species follows the uniform order NH3 > H2S>H2O>HF. The activation barriers for the solvated isomerizations decrease in the order HF>H2O>H2S>NH3 for both pathways. The number of lone pairs on the donor heteroatom as well as the heteroatom electronegativity are factors related to both these trends. Compared to the unsolvated cases, the solvated reactions have transition states which are usually ‘later’ in position along the reaction coordinate, validating the Hammond postulate.

  12. Cation binding to 15-TBA quadruplex DNA is a multiple-pathway cation-dependent process.

    Science.gov (United States)

    Reshetnikov, Roman V; Sponer, Jiri; Rassokhina, Olga I; Kopylov, Alexei M; Tsvetkov, Philipp O; Makarov, Alexander A; Golovin, Andrey V

    2011-12-01

    A combination of explicit solvent molecular dynamics simulation (30 simulations reaching 4 µs in total), hybrid quantum mechanics/molecular mechanics approach and isothermal titration calorimetry was used to investigate the atomistic picture of ion binding to 15-mer thrombin-binding quadruplex DNA (G-DNA) aptamer. Binding of ions to G-DNA is complex multiple pathway process, which is strongly affected by the type of the cation. The individual ion-binding events are substantially modulated by the connecting loops of the aptamer, which play several roles. They stabilize the molecule during time periods when the bound ions are not present, they modulate the route of the ion into the stem and they also stabilize the internal ions by closing the gates through which the ions enter the quadruplex. Using our extensive simulations, we for the first time observed full spontaneous exchange of internal cation between quadruplex molecule and bulk solvent at atomistic resolution. The simulation suggests that expulsion of the internally bound ion is correlated with initial binding of the incoming ion. The incoming ion then readily replaces the bound ion while minimizing any destabilization of the solute molecule during the exchange.

  13. Silica surfaces lubrication by hydrated cations adsorption from electrolyte solutions.

    Science.gov (United States)

    Donose, Bogdan C; Vakarelski, Ivan U; Higashitani, Ko

    2005-03-01

    Adsorption of hydrated cations on hydrophilic surfaces has been related to a variety of phenomena associated with the short-range interaction forces and mechanisms of the adhesive contact between the surfaces. Here we have investigated the effect of the adsorption of cations on the lateral interaction. Using lateral force microscopy (LFM), we have measured the friction force between a silica particle and silica wafer in pure water and in electrolyte solutions of LiCl, NaCl, and CsCl salts. A significant lubrication effect was demonstrated for solutions of high electrolyte concentrations. It was found that the adsorbed layers of smaller and more hydrated cations have a higher lubrication capacity than the layers of larger and less hydrated cations. Additionally, we have demonstrated a characteristic dependence of the friction force on the sliding velocity of surfaces. A mechanism for the observed phenomena based on the microstructures of the adsorbed layers is proposed.

  14. Degradation Mechanism of Cationic Red X-GRL by Ozonation

    Institute of Scientific and Technical Information of China (English)

    Wei Rong ZHAO; Xin Hua XU; Hui Xiang SHI; Da Hui WANG

    2003-01-01

    The degradation mechanism of Cationic Red X-GRL was investigated when the intermediates, the nitrate ion and the pH were analyzed in the ozonation. The degradation of the Cationic Red X-GRL includes the de-auxochrome stage, the decolour stage, and the decomposition of fragment stage. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one becomes the form of an amine compound, and the rest four are transformed into two molecules of nitrogen. In the course of the ozonation of Cationic Red X-GRL, the direct attack of ozone is the main decolour effect.

  15. DFT study on the cycloreversion of thietane radical cations.

    Science.gov (United States)

    Domingo, Luis R; Pérez-Ruiz, Raúl; Argüello, Juan E; Miranda, Miguel A

    2011-06-01

    The molecular mechanism of the cycloreversion (CR) of thietane radical cations has been analyzed in detail at the UB3LYP/6-31G* level of theory. Results have shown that the process takes place via a stepwise mechanism leading to alkenes and thiobenzophenone; alternatively, formal [4+2] cycloadducts are obtained. Thus, the CR of radical cations 1a,b(•+) is initiated by C2-C3 bond breaking, giving common intermediates INa,b. At this stage, two reaction pathways are feasible involving ion molecule complexes IMCa,b (i) or radical cations 4a,b(•+) (ii). Calculations support that 1a(•+) follows reaction pathway ii (leading to the formal [4+2] cycloadducts 5a). By contrast, 1b(•+) follows pathway i, leading to trans-stilbene radical cation (2b(•+)) and thiobenzophenone.

  16. Condensation of nonstochiometric DNA/polycation complexes by divalent cations.

    Science.gov (United States)

    Budker, Vladimir; Trubetskoy, Vladimir; Wolff, Jon A

    2006-12-15

    This study found that divalent cations induced the further condensation of partially condensed DNA within nonstochiometric polycation complexes. The addition of a few mmol of a divalent cation such as calcium reduced by half the inflection point at which DNA became fully condensed by poly-L-lysine (PLL) and a variety of other polycations. The effect on DNA condensation was initially observed using a new method, which is based on the concentration-dependent self-quenching of fluorescent moieties (e.g., rhodamine) covalently linked to the DNA backbone at relatively high densities. Additional analyses, which employed ultracentrifugation, dynamic light scattering, agarose gel electrophoresis, and atomic force microscopy, confirmed the effect of divalent cations. These results provide an additional accounting of the process by which divalent cations induce greater chromatin compaction that is based on the representation of chromatin fibers as a nonstoichiometric polyelectrolyte complex. They also offer a new approach to assemble nonviral vectors for gene therapy.

  17. Migration of Cations and Anions in Amorphous Polymer Electrolytes

    Institute of Scientific and Technical Information of China (English)

    N.A.Stolwijk; S.H.Obeidi; M.Wiencierz

    2007-01-01

    1 Results Polymer electrolytes are used as ion conductors in batteries and fuel cells.Simple systems consist of a polymer matrix complexing an inorganic salt and are fully amorphous at the temperatures of interest.Both cations and anions are mobile and contribute to charge transport.Most studies on polymer electrolytes use the electrical conductivity to characterize the ion mobility.However,conductivity measurements cannot discriminate between cations and anions.This paper reports some recent results fr...

  18. PREPARATION AND CHARACTERISATION OF HYDROPHOBIC AND CATIONIC MONTMORILLONITE

    Institute of Scientific and Technical Information of China (English)

    W. Liu; Y. Ni; H. Xiao

    2004-01-01

    Hydrophilic and cationic montmorillonite is desirable for pitch control in the pulp and paper industry. In this paper, polyaminoamide - epichlorohydrin (PAE)modified montmorillonite was prepared. The modified montmorillonite was characterized using X-ray diffraction, FTIR and thermal gravimetric analysis. The amount of PAE intercalated and cationic charge densities of the modified montmorillonite were determined. Finally, it was found that both the solution and melt-intercalated samples with different charge densities exhibited strong interactions with dispersed colloidal rosin acid.

  19. Competition by meperidine for the organic cation renal excretory system.

    Science.gov (United States)

    Acara, M; Gessner, T; Trudnowski, R J

    1981-07-01

    Renal tubular excretory transport of meperidine was studied using the Sperber preparation in chickens. When urine samples from infused and uninfused kidneys were analyzed for meperidine by gas chromatography, meperidine was always present in greater amounts in the urine from the infused kidney, demonstrating active tubular excretion. Meperidine at an infusion rate of 1 mumole/min, also inhibited the excretion of the organic cations choline and acetylcholine, indicating occupation of the renal organic cation excretory system in the chicken.

  20. Focused fluorescent probe library for metal cations and biological anions.

    Science.gov (United States)

    Rhee, Hyun-Woo; Lee, Sang Wook; Lee, Jun-Seok; Chang, Young-Tae; Hong, Jong-In

    2013-09-09

    A focused fluorescent probe library for metal cations was developed by combining metal chelators and picolinium/quinolinium moieties as combinatorial blocks connected through a styryl group. Furthermore, metal complexes derived from metal chelators having high binding affinities for metal cations were used to construct a focused probe library for phosphorylated biomolecules. More than 250 fluorescent probes were screened for identifying an ultraselective probe for dTTP.

  1. Computer simulation of alkali metal cation-montmorillonite hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Fang-Ru Chou [Columbia Univ., Palisades, NY (United States); Skipper, N.T. [Univ. College, London (United Kingdom); Sposito, G. [Lawrence Berkeley National Lab., CA (United States)

    1997-12-31

    Molecular structure in the interlayers of Li-, Na-, or K-Wyoming montmorillonite with one, two, or three adsorbed water layers was investigated for the first time by concurrent Monte Carlo and molecular dynamics (MD) simulation, based on the Matsouka-Clementi-Yoshimine, (MCY) model of water-water interactions. Calculated layer spacings, as well as interlayer-species self-diffusion coefficients, were in good agreement with available experimental data. Inner-sphere surface complexes of the cations with tetrahedral charge sites were observed for all hydrates, whereas outer-sphere surface complexes of the cations with octahedral charge sites, found also in the one-layer hydrate, tended to dissociate from the clay mineral basal planes into a diffuse layer in the two- and three-layer hydrates. Differences in the interlayer water structure among the hydrates mainly reflected cation solvation, although some water molecules were entrapped within cavities in the montmorillonite surface. All of the interlayer cation and water species exchanged on the time scale (0.2 ns) of the MD simulations. Comparisons with results obtained using, instead of the MCY model, the TIP4P model for water-water, cation-water, and cation-clay interactions indicated that layer spacings and interlayer species mobilities tend to be under-predicted by the TIP4P model.

  2. Complexation Between Cationic Diblock Copolymers and Plasmid DNA

    Science.gov (United States)

    Jung, Seyoung; Reineke, Theresa; Lodge, Timothy

    Deoxyribonucleic acids (DNA), as polyanions, can spontaneously bind with polycations to form polyelectrolyte complexes. When the polycation is a diblock copolymer with one cationic block and one uncharged hydrophilic block, the polyelectrolyte complexes formed with plasmid DNA (pDNA) are often colloidally stable, and show great promise in the field of polymeric gene therapy. While the resulting properties (size, stability, and toxicity to biological systems) of the complexes have been studied for numerous cationic diblocks, the fundamentals of the pDNA-diblock binding process have not been extensively investigated. Herein, we report how the cationic block content of a diblock influences the pDNA-diblock interactions. pDNA with 7164 base pairs and poly(2-deoxy-2-methacrylamido glucopyranose)-block-poly(N-(2-aminoethyl) methacrylamide) (PMAG-b-PAEMA) are used as the model pDNA and cationic diblock, respectively. To vary the cationic block content, two PMAG-b-PAEMA copolymers with similar PMAG block lengths but distinct PAEMA block lengths and a PAEMA homopolymer are utilized. We show that the enthalpy change from pDNA-diblock interactions is dependent on the cationic diblock composition, and is closely associated with both the binding strength and the pDNA tertiary structure.

  3. Photochemical generation, isomerization, and oxygenation of stilbene cation radicals

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, F.D.; Bedell, A.M.; Dykstra, R.E.; Elbert, J.E. (Northwestern Univ., Evanston, IL (USA)); Gould, I.R.; Farid, S. (Eastman Kodak Co., Rochester, NY (USA))

    1990-10-24

    The cation radicals of cis- and trans-stilbene and several of their ring-substituted derivatives have been generated in solution directly by means of pulsed-laser-induced electron transfer to singlet cyanoanthracenes or indirectly via electron transfer from biphenyl to the singlet cyanoanthracene followed by secondary electron transfer from the stilbenes to the biphenyl cation radical. Transient absorption spectra of the cis- and trans-stilbene cation radicals generated by secondary electron transfer are similar to those previously obtained in 77 K matrices. Quantum yields for radical ion-pair cage escape have been measured for direct electron transfer from the stilbenes to three neutral and one charged singlet acceptor. These values increase as the ion-pair energy increases due to decreased rate constants for radical ion-pair return electron transfer, in accord with the predictions of Marcus theory for highly exergonic electron transfer. Cage-escape efficiencies are larger for trans- vs cis-stilbene cation radicals, possibly due to the greater extent of charge delocalization in the planar trans vs nonpolar cis cation radicals. Cage-escape stilbene cation radicals can initiate a concentration-dependent one way cis- {yields} trans-stilbene isomerization reaction.

  4. Tunable states of interlayer cations in two-dimensional materials

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Numata, K. [Department of Environmental Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan); Dai, W. [Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071 (China); Hunger, M. [Institute of Chemical Technology, University of Stuttgart, 70550 Stuttgart (Germany)

    2014-03-31

    The local state of cations inside the Ångstrom-scale interlayer spaces is one of the controlling factors for designing sophisticated two-dimensional (2D) materials consisting of 2D nanosheets. In the present work, the molecular mechanism on how the interlayer cation states are induced by the local structures of the 2D nanosheets is highlighted. For this purpose, the local states of Na cations in inorganic 2D materials, in which the compositional fluctuations of a few percent are introduced in the tetrahedral and octahedral units of the 2D nanosheets, were systematically studied by means of {sup 23}Na magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) and {sup 23}Na multiple-quantum MAS (MQMAS) NMR spectroscopy. In contrast with an uniform distribution of Na cations expected so far, various well-defined cation states sensitive to the local structures of the 2D nanosheets were identified. The tunability of the interlayer cation states along with the local structure of the 2D nanosheets, as the smallest structural unit of the 2D material, is discussed.

  5. Synthesis and characterisation of cationically modified phospholipid polymers.

    Science.gov (United States)

    Lewis, Andrew L; Berwick, James; Davies, Martyn C; Roberts, Clive J; Wang, Jin-Hai; Small, Sharon; Dunn, Anthony; O'Byrne, Vincent; Redman, Richard P; Jones, Stephen A

    2004-07-01

    Phospholipid-like copolymers based on 2-(methacryloyloxyethyl) phosphorylcholine were synthesised using monomer-starved free radical polymerisation methods and incorporating cationic charge in the form of the choline methacrylate monomer in amounts varying from 0 to 30 wt%, together with a 5 wt% silyl cross-linking agent in order to render them water-insoluble once thermally cured. Characterisation using a variety of techniques including nuclear magnetic resonance spectroscopy, high-pressure liquid chromatography and gel permeation chromatography showed the cationic monomer did not interfere with the polymerisation and that the desired amount of charge had been incorporated. Gravimetric and differential scanning calorimetry methods were used to evaluate the water contents of polymer membranes cured at 70 degrees C, which was seen to increase with increasing cation content, producing materials with water contents ranging from 50% to 98%. Surface plasmon resonance indicated that the coatings swelled rapidly in water, the rate and extent of swelling increasing with increasing cation level. Dynamic contact angle showed that coatings of all the polymers possessed a hydrophobic surface when dry in air, characteristic of the alkyl chains expressed at the surface (>100 degrees advancing angle). Rearrangement of the hydrophilic groups to the surface occurred once wet, to produce highly wettable surfaces with a decrease in advancing angle with increasing cation content. Atomic force microscopy showed all polymer films to be smooth with no features in topographical or phase imaging. Mechanical properties of the dry films were also unaffected by the increase in cation content.

  6. Modulatory role of bivalent cations on reward system.

    Science.gov (United States)

    Nechifor, M; Chelărescu, D

    2008-01-01

    Bivalent cations (Ca, Mg, Zn, Mn etc.) modulate activity of reward system (RS). At physiologic levels they may influence all components of RS. There are influenced behavioral reactions at physiological stimuli and all essential elements of drug dependence (compulsive intake of substance, craving, reinforcement, withdrawal syndrom, relapse and reinstatement of intake) The fact that some cations (e.g. calcium) enhance some of the aspects of drug dependence and others (e.g. magnesium, zinc) decrease intensity of this process show that ratio between intra- and extracellular in the brain of these cations is important for the function of RS. Among actions of different cations at the level of RS there are important differences. Their mecahanism of action are common in part and specific in other. It is important the fact that modulatory action appear at physiologic cation concentrations (that could be reached at therapeutic doses). Modulatory action is related to ratio between concetrations of different bivalent cations and is exerted both in normal or pathologic conditions.

  7. Does the cation really matter? The effect of modifying an ionic liquid cation on an SN2 process.

    Science.gov (United States)

    Tanner, Eden E L; Yau, Hon Man; Hawker, Rebecca R; Croft, Anna K; Harper, Jason B

    2013-09-28

    The rate of reaction of a Menschutkin process in a range of ionic liquids with different cations was investigated, with temperature-dependent kinetic data giving access to activation parameters for the process in each solvent. These data, along with molecular dynamics simulations, demonstrate the importance of accessibility of the charged centre on the cation and that the key interactions are of a generalised electrostatic nature.

  8. Sorption of the organic cation metoprolol on silica gel from its aqueous solution considering the competition of inorganic cations.

    Science.gov (United States)

    Kutzner, Susann; Schaffer, Mario; Börnick, Hilmar; Licha, Tobias; Worch, Eckhard

    2014-05-01

    Systematic batch experiments with the organic monovalent cation metoprolol as sorbate and the synthetic material silica gel as sorbent were conducted with the aim of characterizing the sorption of organic cations onto charged surfaces. Sorption isotherms for metoprolol (>99% protonated in the tested pH of around 6) in competition with mono- and divalent inorganic cations (Na(+), NH4(+), Ca(2+), and Mg(2+)) were determined in order to assess their influence on cation exchange processes and to identify the role of further sorptive interactions. The obtained sorption isotherms could be described well by an exponential function (Freundlich isotherm model) with consistent exponents (about 0.8). In general, a decreasing sorption of metoprolol with increasing concentrations in inorganic cations was observed. Competing ions of the same valence showed similar effects. A significant sorption affinity of metoprolol with ion type dependent Freundlich coefficients KF,0.77 between 234.42 and 426.58 (L/kg)(0.77) could still be observed even at very high concentrations of competing inorganic cations. Additional column experiments confirm this behavior, which suggests the existence of further relevant interactions beside cation exchange. In subsequent batch experiments, the influence of mixtures with more than one competing ion and the effect of a reduced negative surface charge at a pH below the point of zero charge (pHPZC ≈ 2.5) were also investigated. Finally, the study demonstrates that cation exchange is the most relevant but not the sole mechanism for the sorption of metoprolol on silica gel.

  9. Cation Uptake and Allocation by Red Pine Seedlings under Cation-Nutrient Stress in a Column Growth Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zhenqing; Balogh-Brunstad, Zsuzsanna; Grant, Michael R.; Harsh, James B.; Gill, Richard; Thomashow, Linda; Dohnalkova, Alice; Stacks, Daryl; Letourneau, Melissa; Keller, Chester K.

    2014-01-10

    Background and Aims Plant nutrient uptake is affected by environmental stress, but how plants respond to cation-nutrient stress is poorly understood. We assessed the impact of varying degrees of cation-nutrient limitation on cation uptake in an experimental plant-mineral system. Methods Column experiments, with red pine (Pinus resinosa Ait.) seedlings growing in sand/mineral mixtures, were conducted for up to nine months under a range of Ca- and K-limited conditions. The Ca and K were supplied from both minerals and nutrient solutions with varying Ca and K concentrations. Results Cation nutrient stress had little impact on carbon allocation after nine months of plant growth and K was the limiting nutrient for biomass production. The Ca/Sr and K/Rb ratio results allowed independent estimation of dissolution incongruency and discrimination against Sr and Rb during cation uptake processes. The fraction of K in biomass from biotite increased with decreasing K supply from nutrient solutions. The mineral anorthite was consistently the major source of Ca, regardless of nutrient treatment. Conclusions Red pine seedlings exploited more mineral K in response to more severe K deficiency. This did not occur for Ca. Plant discrimination factors must be carefully considered to accurately identify nutrient sources using cation tracers.

  10. Lack of association between a cationic protein and a cationic fluorosurfactant.

    Science.gov (United States)

    Macakova, Lubica; Nordstierna, Lars; Karlsson, Göran; Blomberg, Eva; Furó, István

    2007-01-16

    Surface tension, 19F and 1H NMR spectroscopy, and cryotransmission electron microscopy are used to characterize the state of association in aqueous solutions of a fluorosurfactant CF3(CF2)nSO2NH(CH2)3-4N(CH3)3+ I- (n = 8, 6) with and without lysozyme added. In the absence of lysozyme, we find monomers, small aggregates, and large vesicles to coexist, with the individual fluorosurfactant molecules exchanging slowly (>1 ms) among those states. When both lysozyme and fluorosurfactant are present in the solution, they have no measurable influence on the physical state of the other. In contrast, a hydrogenated cationic surfactant with the same headgroup, hexadecyltrimethylammonium bromide, is shown to associate to lysozyme.

  11. Hydration of cations: a key to understanding of specific cation effects on aggregation behaviors of PEO-PPO-PEO triblock copolymers.

    Science.gov (United States)

    Lutter, Jacob C; Wu, Tsung-yu; Zhang, Yanjie

    2013-09-05

    This work reports results from the interactions of a series of monovalent and divalent cations with a triblock copolymer, poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO). Phase transition temperatures of the polymer in the presence of chloride salts with six monovalent and eight divalent cations were measured using an automated melting point apparatus. The polymer undergoes a two-step phase transition, consisting of micellization of the polymer followed by aggregation of the micelles, in the presence of all the salts studied herein. The results suggest that hydration of cations plays a key role in determining the interactions between the cations and the polymer. The modulation of the phase transition temperature of the polymer by cations can be explained as a balance between three interactions: direct binding of cations to the oxygen in the polymer chains, cations sharing one water molecule with the polymer in their hydration layer, and cations interacting with the polymer via two water molecules. Monovalent cations Na(+), K(+), Rb(+), and Cs(+) do not bind to the polymer, while Li(+) and NH4(+) and all the divalent cations investigated including Mg(2+), Ca(2+), Sr(2+), Ba(2+), Co(2+), Ni(2+), Cu(2+), and Cd(2+) bind to the polymer. The effects of the cations correlate well with their hydration thermodynamic properties. Mechanisms for cation-polymer interactions are discussed.

  12. Endocytosis of cationized ferritin by coated vesicles of soybean protoplasts.

    Science.gov (United States)

    Tanchak, M A; Griffing, L R; Mersey, B G; Fowke, L C

    1984-12-01

    Soybean (Glycine max (L.) Merr.) protoplasts have been surface-labelled with cationized ferritin, and the fate of the label has been followed ultrastructurally. Endocytosis of the label occurs via the coated-membrane system. The pathway followed by the label, once it has been taken into the interior of the protoplast, appears to be similar to that found during receptor-mediated endocytosis in animal cells. Cationized ferritin is first seen in coated vesicles but rapidly appears in smooth vesicles. Labelled, partially coated vesicles are occasionally observed, indicating that the smooth vesicles may have arisen by the uncoating of coated vesicles. Structures which eventually become labelled with cationized ferritin include multivesicular bodies, dictyosomes, large smooth vesicles, and a system of partially coated reticula.

  13. Infrared Spectroscopic Investigation on CH Bond Acidity in Cationic Alkanes

    Science.gov (United States)

    Matsuda, Yoshiyuki; Xie, Min; Fujii, Asuka

    2016-06-01

    We have demonstrated large enhancements of CH bond acidities in alcohol, ether, and amine cations through infrared predissociation spectroscopy based on the vacuum ultraviolet photoionization detection. In this study, we investigate for the cationic alkanes (pentane, hexane, and heptane) with different alkyl chain lengths. The σ electrons are ejected in the ionization of alkanes, while nonbonding electrons are ejected in ionization of alcohols, ethers, and amines. Nevertheless, the acidity enhancements of CH in these cationic alkanes have also been demonstrated by infrared spectroscopy. The correlations of their CH bond acidities with the alkyl chain lengths as well as the mechanisms of their acidity enhancements will be discussed by comparison of infrared spectra and theoretical calculations.

  14. Radical Addition to Iminium Ions and Cationic Heterocycles

    Directory of Open Access Journals (Sweden)

    Johannes Tauber

    2014-10-01

    Full Text Available Carbon-centered radicals represent highly useful reactive intermediates in organic synthesis. Their nucleophilic character is reflected by fast additions to electron deficient C=X double bonds as present in iminium ions or cationic heterocycles. This review covers diverse reactions of preformed or in situ-generated cationic substrates with various types of C-radicals, including alkyl, alkoxyalkyl, trifluoromethyl, aryl, acyl, carbamoyl, and alkoxycarbonyl species. Despite its high reactivity, the strong interaction of the radical’s SOMO with the LUMO of the cation frequently results in a high regioselectivity. Intra- and intermolecular processes such as the Minisci reaction, the Porta reaction, and the Knabe rearrangement will be discussed along with transition metal and photoredox catalysis or electrochemical methods to generate the odd-electron species.

  15. A covalent attraction between two molecular cation TTF·~+

    Institute of Scientific and Technical Information of China (English)

    WANG FangFang; WANG Yi; WANG BingQiang; WANG YinFeng; MA Fang; Li ZhiRu

    2009-01-01

    The optimized structure of the tetrathiafulvalence radical-cation dimer (TTF·~+-TTF·~+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·~+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π/π bonding with a telescope shape.The covalent π/π bonding has the bonding energy of about-21 kcal·mol~(-1) and is concealed by the Coulombic repulsion between two TTF·~+ cations.This intermolecular covalent attraction also influences the structure of the TTF·~+ subunit,I.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.

  16. A covalent attraction between two molecular cation TTF·~+

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The optimized structure of the tetrathiafulvalence radical-cation dimer(TTF·+-TTF·+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π /π bonding with a telescope shape.The covalent π /π bonding has the bonding energy of about -21 kcal·mol-1 and is concealed by the Coulombic repulsion between two TTF·+ cations.This intermolecular covalent attraction also influences the structure of the TTF·+ subunit,i.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.

  17. Cationic lipids delay the transfer of plasmid DNA to lysosomes.

    Science.gov (United States)

    Wattiaux, R; Jadot, M; Laurent, N; Dubois, F; Wattiaux-De Coninck, S

    1996-10-14

    Plasmid 35S DNA, naked or associated with different cationic lipid preparations was injected to rats. Subcellular distribution of radioactivity in the liver one hour after injection, was established by centrifugation methods. Results show that at that time, 35S DNA has reached lysosomes. On the contrary, when 35S DNA was complexed with lipids, radioactivity remains located in organelles whose distribution after differential and isopycnic centrifugation, is clearly distinct from that of arylsulfatase, lysosome marker enzyme. Injection of Triton WR 1339, a specific density perturbant of lysosomes, four days before 35S DNA injection causes a density decrease of radioactivity bearing structures, apparent one hour after naked 35S DNA injection but visible only after more than five hours, when 35S DNA associated with a cationic lipid is injected. These observations show that cationic lipids delay the transfer to lysosomes, of plasmid DNA taken up by the liver.

  18. Surface hopping investigation of the relaxation dynamics in radical cations

    Energy Technology Data Exchange (ETDEWEB)

    Assmann, Mariana; Matsika, Spiridoula, E-mail: smatsika@temple.edu [Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States); Weinacht, Thomas [Department of Physics, Stony Brook University, Stony Brook, New York 11794 (United States)

    2016-01-21

    Ionization processes can lead to the formation of radical cations with population in several ionic states. In this study, we examine the dynamics of three radical cations starting from an excited ionic state using trajectory surface hopping dynamics in combination with multiconfigurational electronic structure methods. The efficiency of relaxation to the ground state is examined in an effort to understand better whether fragmentation of cations is likely to occur directly on excited states or after relaxation to the ground state. The results on cyclohexadiene, hexatriene, and uracil indicate that relaxation to the ground ionic state is very fast in these systems, while fragmentation before relaxation is rare. Ultrafast relaxation is facilitated by the close proximity of electronic states and the presence of two- and three-state conical intersections. Examining the properties of the systems in the Franck-Condon region can give some insight into the subsequent dynamics.

  19. Theoretical Studies on the Interactions of Cations with Diazine

    Institute of Scientific and Technical Information of China (English)

    CHEN Xing; WU Wen-Peng; ZHANG Jing-Lai; CAO Ze-Xing

    2006-01-01

    Density functional theory and MP2 calculations have been used to determine the geometries, stabilities, binding energies, and dissociative properties of cation-diazine complexes Mn+-C4H4N2 (Mn+ = Li+, B+, Al+, Be2+, Mg2+, Ca2+). The calculated results indicate that most complexes are stable except the π complexes of Ca2+-pyridazine, Ca2+-pyrazine, Al+-pyrimidine and Al+-pyrimidine. The σ complexes are generally much more stable than their π counterparts. Among the π complexes, the cation-pyrazine π complexes have slightly higher stability. The nature of the ion-molecule interactions has been discussed by the natural bond orbital analysis and frontier molecular orbital interactions. In these σ complexes, there is stronger covalent interaction between B+ and diazine. In the selected π complexes, B+ and Be2+ have stronger covalent interaction with diazine, while the other cations mainly have electrostatic interaction with diazine.

  20. Solubility and transport of cationic and anionic patterned nanoparticles

    Science.gov (United States)

    Su, Jiaye; Guo, Hongxia; Olvera de La Cruz, Monica

    2012-02-01

    Diffusion and transport of nanoparticles (NPs) though nanochannels is important for desalination, drug delivery, and biomedicine. Their surface composition dictate their efficiency separating them by reverse osmosis, delivering into into cells, as well as their toxicity. We analyze bulk diffusion and transport through nanochannels of NPs with different hydrophobic-hydrophilic patterns achieved by coating a fraction of the NP sites with positive or negative charges via explicit solvent molecular dynamics simulations. The cationic NPs are more affected by the patterns, less water soluble, and have higher diffusion constants and fluxes than their anionic NPs counterparts. The NP-water interaction dependence on surface pattern and field strength explains these observations. For equivalent patterns, anionic NPs solubilize more than cationic NPs since the Coulomb interaction of free anionic NPs, which are much stronger than hydrophobic NP-water interactions, are about twice that of cationic NPs.

  1. Cationization of Alpha-Cellulose to Develop New Sustainable Products

    Directory of Open Access Journals (Sweden)

    Ana Moral

    2015-01-01

    Full Text Available Papermaking has been using high quantities of retention agents, mainly cationic substances and organic compounds such as polyamines. The addition of these agents is related to economic and environmental issues, increasing contamination of the effluents. The aim of this work is to develop a cationic polymer for papermaking purposes based on the utilization of alpha-cellulose. The cationization of mercerized alpha-cellulose with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC is governed by a pseudo-second-order reaction. The initial amorphous fraction of cellulose is reacted with CHPTAC until the equilibrium value of nitrogen substitution is reached. Nitrogen is incorporated as a quaternary ammonium group in the polymer. Also, the kinetic constant increased with decreasing crystallinity index, showing the importance of the previous alkalization stage. The use of modified natural polysaccharides is a sustainable alternative to synthetic, nonbiodegradable polyelectrolytes and thus is desirable with a view to developing new products and new processes.

  2. Comparison of Cation Adsorption by Isostructural Rutile and Cassiterite

    Energy Technology Data Exchange (ETDEWEB)

    Machesky, Michael L. [Illinois State Water Survey, Champaign, IL; Wesolowski, David J [ORNL; Rosenqvist, Jorgen K [ORNL; Predota, M. [University of South Bohemia, Czech Republic; Vlcek, Lukas [ORNL; Ridley, Moira K [ORNL; Kohli, V [Oak Ridge National Laboratory (ORNL); Zhang, Zhan [Argonne National Laboratory (ANL); Fenter, Paul [Argonne National Laboratory (ANL); Cummings, Peter T [ORNL; Lvov, Serguei N. [Pennsylvania State University; Fedkin, Mark V [ORNL; Rodriguez-Santiago, V [Oak Ridge National Laboratory (ORNL); Kubicki, James D. [Pennsylvania State University; Bandura, Andrei V. [St. Petersburg State University, St. Petersburg, Russia

    2011-01-01

    Macroscopic net proton charging curves for powdered rutile and cassiterite specimens with the (110) Crystal face predominant, as a function of pH in RbCl and NaCl solutions, trace SrCl2 in NaCl, and trace ZnCl2 in NaCl and Na Triflate solutions, are compared to corresponding molecular-level information obtained from static DFT optimizations and classical MD simulations, as well as synchrotron X-ray methods. The similarities and differences in the macroscopic charging behavior of rutile and cassiterite largely reflect the cation binding modes observed at the molecular level. Cation adsorption is primarily inner-sphere on both isostructural (110) surfaces, despite predictions that outer-sphere binding should predominate on low bulk dielectric constant oxides such as cassiterite ( bulk 11). Inner-sphere adsorption is also significant for Rb and Na on neutral surfaces, whereas Cl- binding is predominately outer-sphere. As negative surface charge increases, relatively more Rb , Na , and especially Sr2 are bound in highly desolvated tetradentate fashion on the rutile (110) surface, largely accounting for enhanced negative charge development relative to cassiterite. Charging curves in the presence of Zn2 are very steep but similar for both oxides, reflective of Zn2 hydrolysis (and accompanying proton release) during the adsorption process, and the similar binding modes for ZnOH on both surfaces. These results suggest that differences in cation adsorption between high and low bulk dielectric constant oxides are more subtly related to the relative degree of cation desolvation accompanying inner-sphere binding (i.e., more tetradentate binding on rutile), rather than distinct inner- and outer-sphere adsorption modes. Cation desolvation may be favored at the rutile (110) surface in part because inner-sphere water molecules are bound further from and less tightly than on the cassiterite (110) surface. Hence, their removal upon inner-sphere cation binding is relatively more

  3. Comparison of cation adsorption by isostructural rutile and cassiterite.

    Science.gov (United States)

    Machesky, Michael; Wesolowski, David; Rosenqvist, Jörgen; Předota, Milan; Vlcek, Lukas; Ridley, Moira; Kohli, Vaibhav; Zhang, Zhan; Fenter, Paul; Cummings, Peter; Lvov, Serguei; Fedkin, Mark; Rodriguez-Santiago, Victor; Kubicki, James; Bandura, Andrei

    2011-04-19

    Macroscopic net proton charging curves for powdered rutile and cassiterite specimens with the (110) crystal face predominant, as a function of pH in RbCl and NaCl solutions, trace SrCl(2) in NaCl, and trace ZnCl(2) in NaCl and Na Triflate solutions, are compared to corresponding molecular-level information obtained from static DFT optimizations and classical MD simulations, as well as synchrotron X-ray methods. The similarities and differences in the macroscopic charging behavior of rutile and cassiterite largely reflect the cation binding modes observed at the molecular level. Cation adsorption is primarily inner-sphere on both isostructural (110) surfaces, despite predictions that outer-sphere binding should predominate on low bulk dielectric constant oxides such as cassiterite (ε(bulk) ≈ 11). Inner-sphere adsorption is also significant for Rb(+) and Na(+) on neutral surfaces, whereas Cl(-) binding is predominately outer-sphere. As negative surface charge increases, relatively more Rb(+), Na(+), and especially Sr(2+) are bound in highly desolvated tetradentate fashion on the rutile (110) surface, largely accounting for enhanced negative charge development relative to cassiterite. Charging curves in the presence of Zn(2+) are very steep but similar for both oxides, reflective of Zn(2+) hydrolysis (and accompanying proton release) during the adsorption process, and the similar binding modes for ZnOH(+) on both surfaces. These results suggest that differences in cation adsorption between high and low bulk dielectric constant oxides are more subtly related to the relative degree of cation desolvation accompanying inner-sphere binding (i.e., more tetradentate binding on rutile), rather than distinct inner- and outer-sphere adsorption modes. Cation desolvation may be favored at the rutile (110) surface in part because inner-sphere water molecules are bound further from and less tightly than on the cassiterite (110) surface. Hence, their removal upon inner

  4. Determination of Cationic Surfactant by Laser Thermal Lens Spectrometry

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel method for the determination of cationic surfactant by laser thermal lens spectrometry was developed. It was based on the reaction between 1-hydroxy-2-(5-nitro-2-Pyri-dylazo)-8-aminonaphthalene-3,6-disulfonic acid (5-NO2-PAH) and cationic surfactant to form 1:2 ionic association complex in a weakly basic medium (pH 9.44). The determination conditions and the mechanism were discussed. The method has been applied to the analysis of wastewater and moat water samples.

  5. Cationically polymerizable monomers derived from renewable sources. Annual performance report

    Energy Technology Data Exchange (ETDEWEB)

    Crivello, J.V.

    1992-10-01

    The objectives of this project are to design and synthesize novel monomers which orginate from renewable biological sources and to carry out their rapid, efficient, pollution-free and energy efficient cationic polymerization to useful products under the influence of ultraviolet light or heat. A summary of the results of the past year`s research on cationically polymerizable monomers derived from renewable sources is presented. Three major areas of investigation corresponding to the different classes of naturally occurring starting materials were investigated; epoxidized terpenes and natural rubber and vinyl ethers from alcohols and carbohydrates.

  6. Dilatometric, refractometric and viscometric study of lysozyme-cation interaction.

    Science.gov (United States)

    Abad, C; Trueba, M; Campos, A; Figueruelo, J E

    1981-11-01

    The interaction between hen egg-white lysozyme and Cu(II) or Co(II) cations has been studied by dilatometry, equilibrium dialysis-differential refractometry and viscometry at different metal cation concentrations. Delta V isotherms in copper and cobalt solutions have been obtained from dilatometry. Preferential adsorption parameters and specific viscosity have been determined from refractometric and viscosimetric measurements. It has been observed that this interaction produces structural alterations in lysozyme. The magnitude of these conformational changes depends on the metal ion and protein concentration. The results obtained using the three techniques are in good agreement.

  7. THE APPLICATION OF CATIONIC POLYACRYLAMIDE AS DRAINAGE AND RETENTION AIDS

    Institute of Scientific and Technical Information of China (English)

    JinWang; KefuChen; FushanChent; ChuanshanZhao; RendangYang

    2004-01-01

    Cationic polyacrylamide (CPAM) which was prepared through complex initiation system in laboratory and cationic polyacrylamide (Ciba) were used asretention and drainage aids for bleached wheat strawpulp. The influences of (polydiallyldimethlammonium chloride) PDADMAC and PDADMAC/CPAMon Zeta potential and drainability of pulp was investigated. The dual drainage and retention systems suchas CPAM/modified bentonite, CPAM/colloidal SiO2,as well as their comparison between the two systemswere discussed, and the optimal dosages of additiveswere determined. The results showed that: the complex systems can further enhance filler retention,drainability of pulp and strength properties of paper.

  8. Alloyed copper chalcogenide nanoplatelets via partial cation exchange reactions.

    Science.gov (United States)

    Lesnyak, Vladimir; George, Chandramohan; Genovese, Alessandro; Prato, Mirko; Casu, Alberto; Ayyappan, S; Scarpellini, Alice; Manna, Liberato

    2014-08-26

    We report the synthesis of alloyed quaternary and quinary nanocrystals based on copper chalcogenides, namely, copper zinc selenide-sulfide (CZSeS), copper tin selenide-sulfide (CTSeS), and copper zinc tin selenide-sulfide (CZTSeS) nanoplatelets (NPLs) (∼20 nm wide) with tunable chemical composition. Our synthesis scheme consisted of two facile steps: i.e., the preparation of copper selenide-sulfide (Cu2-xSeyS1-y) platelet shaped nanocrystals via the colloidal route, followed by an in situ cation exchange reaction. During the latter step, the cation exchange proceeded through a partial replacement of copper ions by zinc or/and tin cations, yielding homogeneously alloyed nanocrystals with platelet shape. Overall, the chemical composition of the alloyed nanocrystals can easily be controlled by the amount of precursors that contain cations of interest (e.g., Zn, Sn) to be incorporated/alloyed. We have also optimized the reaction conditions that allow a complete preservation of the size, morphology, and crystal structure as that of the starting Cu2-xSeyS1-y NPLs. The alloyed NPLs were characterized by optical spectroscopy (UV-vis-NIR) and cyclic voltammetry (CV), which demonstrated tunability of their light absorption characteristics as well as their electrochemical band gaps.

  9. Cu Vacancies Boost Cation Exchange Reactions in Copper Selenide Nanocrystals.

    Science.gov (United States)

    Lesnyak, Vladimir; Brescia, Rosaria; Messina, Gabriele C; Manna, Liberato

    2015-07-29

    We have investigated cation exchange reactions in copper selenide nanocrystals using two different divalent ions as guest cations (Zn(2+) and Cd(2+)) and comparing the reactivity of close to stoichiometric (that is, Cu2Se) nanocrystals with that of nonstoichiometric (Cu(2-x)Se) nanocrystals, to gain insights into the mechanism of cation exchange at the nanoscale. We have found that the presence of a large density of copper vacancies significantly accelerated the exchange process at room temperature and corroborated vacancy diffusion as one of the main drivers in these reactions. Partially exchanged samples exhibited Janus-like heterostructures made of immiscible domains sharing epitaxial interfaces. No alloy or core-shell structures were observed. The role of phosphines, like tri-n-octylphosphine, in these reactions, is multifaceted: besides acting as selective solvating ligands for Cu(+) ions exiting the nanoparticles during exchange, they also enable anion diffusion, by extracting an appreciable amount of selenium to the solution phase, which may further promote the exchange process. In reactions run at a higher temperature (150 °C), copper vacancies were quickly eliminated from the nanocrystals and major differences in Cu stoichiometries, as well as in reactivities, between the initial Cu2Se and Cu(2-x)Se samples were rapidly smoothed out. These experiments indicate that cation exchange, under the specific conditions of this work, is more efficient at room temperature than at higher temperature.

  10. Fusion Pore Diameter Regulation by Cations Modulating Local Membrane Anisotropy

    Directory of Open Access Journals (Sweden)

    Doron Kabaso

    2012-01-01

    Full Text Available The fusion pore is an aqueous channel that is formed upon the fusion of the vesicle membrane with the plasma membrane. Once the pore is open, it may close again (transient fusion or widen completely (full fusion to permit vesicle cargo discharge. While repetitive transient fusion pore openings of the vesicle with the plasma membrane have been observed in the absence of stimulation, their frequency can be further increased using a cAMP-increasing agent that drives the opening of nonspecific cation channels. Our model hypothesis is that the openings and closings of the fusion pore are driven by changes in the local concentration of cations in the connected vesicle. The proposed mechanism of fusion pore dynamics is considered as follows: when the fusion pore is closed or is extremely narrow, the accumulation of cations in the vesicle (increased cation concentration likely leads to lipid demixing at the fusion pore. This process may affect local membrane anisotropy, which reduces the spontaneous curvature and thus leads to the opening of the fusion pore. Based on the theory of membrane elasticity, we used a continuum model to explain the rhythmic opening and closing of the fusion pore.

  11. Cationic PAMAM dendrimers aggressively initiate blood clot formation.

    Science.gov (United States)

    Jones, Clinton F; Campbell, Robert A; Brooks, Amanda E; Assemi, Shoeleh; Tadjiki, Soheyl; Thiagarajan, Giridhar; Mulcock, Cheyanne; Weyrich, Andrew S; Brooks, Benjamin D; Ghandehari, Hamidreza; Grainger, David W

    2012-11-27

    Poly(amidoamine) (PAMAM) dendrimers are increasingly studied as model nanoparticles for a variety of biomedical applications, notably in systemic administrations. However, with respect to blood-contacting applications, amine-terminated dendrimers have recently been shown to activate platelets and cause a fatal, disseminated intravascular coagulation (DIC)-like condition in mice and rats. We here demonstrate that, upon addition to blood, cationic G7 PAMAM dendrimers induce fibrinogen aggregation, which may contribute to the in vivo DIC-like phenomenon. We demonstrate that amine-terminated dendrimers act directly on fibrinogen in a thrombin-independent manner to generate dense, high-molecular-weight fibrinogen aggregates with minimal fibrin fibril formation. In addition, we hypothesize this clot-like behavior is likely mediated by electrostatic interactions between the densely charged cationic dendrimer surface and negatively charged fibrinogen domains. Interestingly, cationic dendrimers also induced aggregation of albumin, suggesting that many negatively charged blood proteins may be affected by cationic dendrimers. To investigate this further, zebrafish embryos were employed to more specifically determine the speed of this phenomenon and the pathway- and dose-dependency of the resulting vascular occlusion phenotype. These novel findings show that G7 PAMAM dendrimers significantly and adversely impact many blood components to produce rapid coagulation and strongly suggest that these effects are independent of classic coagulation mechanisms. These results also strongly suggest the need to fully characterize amine-terminated PAMAM dendrimers in regard to their adverse effects on both coagulation and platelets, which may contribute to blood toxicity.

  12. Cation binding site of cytochrome c oxidase: progress report.

    Science.gov (United States)

    Vygodina, Tatiana V; Kirichenko, Anna; Konstantinov, Alexander A

    2014-07-01

    Cytochrome c oxidase from bovine heart binds Ca(2+) reversibly at a specific Cation Binding Site located near the outer face of the mitochondrial membrane. Ca(2+) shifts the absorption spectrum of heme a, which allowed earlier the determination of the kinetic and equilibrium characteristics of the binding, and, as shown recently, the binding of calcium to the site inhibits cytochrome oxidase activity at low turnover rates of the enzyme [Vygodina, Т., Kirichenko, A., Konstantinov, A.A (2013). Direct Regulation of Cytochrome c Oxidase by Calcium Ions. PloS ONE 8, e74436]. This paper summarizes further progress in the studies of the Cation Binding Site in this group presenting the results to be reported at 18th EBEC Meeting in Lisbon, 2014. The paper revises specificity of the bovine oxidase Cation Binding Site for different cations, describes dependence of the Ca(2+)-induced inhibition on turnover rate of the enzyme and reports very high affinity binding of calcium with the "slow" form of cytochrome oxidase. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Guest Editors: Manuela Pereira and Miguel Teixeira.

  13. Structure and Reactivity of the Cysteine Methyl Ester Radical Cation

    NARCIS (Netherlands)

    Osburn, S.; Steill, J. D.; Oomens, J.; O' Hair, R. A. J.; Van Stipdonk, M.; Ryzhov, V.

    2011-01-01

    The structure and reactivity of the cysteine methyl ester radical cation, CysOMe(center dot+), have been examined in the gas phase using a combination of experiment and density functional theory (DFT) calculations. CysOMe(center dot+) undergoes rapid ion molecule reactions with dimethyl disulfide, a

  14. [Synthesis of functionalized cyanines. Fluorescence properties following complexation of cations].

    Science.gov (United States)

    Mazières, M R; Duprat, C; Sutra, E; Lamandé, L; Bergon, M; Bellan, J; Wolf, J G; Roques, C

    2003-01-01

    The ionophoric properties of podands containing dioxazaphosphocane moieties linked by inactive spacers were studied. To increase the detection sensibility of these compounds we introduced a cyanine as spacer. Fluorescence analysis demonstrated the interest of cyanines as active spacers since the complexation by cations as Ca2+ and Mg2+ gives an enhancement of the emission intensity.

  15. Metal Cations in G-Quadruplex Folding and Stability

    Science.gov (United States)

    Bhattacharyya, Debmalya; Mirihana Arachchilage, Gayan; Basu, Soumitra

    2016-09-01

    This review is focused on the structural and physico-chemical aspects of metal cation coordination to G-Quadruplexes (GQ) and their effects on GQ stability and conformation. G-Quadruplex structures are non-canonical secondary structures formed by both DNA and RNA. G-quadruplexes regulate a wide range of important biochemical processes. Besides the sequence requirements, the coordination of monovalent cations in the GQ is essential for its formation and determines the stability and polymorphism of GQ structures. The nature, location and dynamics of the cation coordination and their impact on the overall GQ stability are dependent on several factors such as the ionic radii, hydration energy and the bonding strength to the O6 of guanines. The intracellular monovalent cation concentration and the localized ion concentrations determine the formation of GQs and can potentially dictate their regulatory roles. A wide range of biochemical and biophysical studies on an array of GQ enabling sequences have generated at a minimum the knowledge base that allows us to often predict the stability of GQs in presence of the physiologically relevant metal ions, however, prediction of conformation of such GQs is still out of the realm.

  16. Denatured Thermodynamics of Proteins in Weak Cation-exchange Chromatography

    Institute of Scientific and Technical Information of China (English)

    LI Rong; CHEN Guo-Liang

    2003-01-01

    The thermostability of some proteins in weak cation-exchange chromatography was investigated at 20-80 ℃. The results show that there is a fixed thermal denaturation transition temperature for each protein. The appearance of the thermal transition temperature indicates that the conformations of the proteins are destroyed seriously. The thermal behavior of the proteins in weak cation-exchange and hydrophobic interaction chromatographies were compared in a wide temperature range. It was found that the proteins have a higher thermostability in a weak cation-exchange chromatography system. The thermodynamic parameters(ΔH0, ΔS0) of those proteins were determined by means of Vant Hoff relationship(lnk-1/T). According to standard entropy change(ΔS0), the conformational change of the proteins was judged in the chromatographic process. The linear relationships between ΔH0 and ΔS0 can be used to evaluate "compensation temperature"(β) at the protein denaturation and identify the identity of the protein retention mechanism in weak cation-exchange chromatography.

  17. Synthesis and Cation Complexation of Lariat Calix[4 ] crowns

    Institute of Scientific and Technical Information of China (English)

    SHI Zheng-Wei; JIN Chuan-Ming; LU Guo-Yuan

    2003-01-01

    @@ Calixcrowns carrying bridging polyethyleneoxy moieties on the lower rim, which combine calixarene and crown ether in a single molecule, are a novel class of host compounds which have attracted increasing attention because of their increased ability for selective complexation of cations and neutral molecules compared with crown ethers or cal ixarenes.

  18. Two different cationic positions in Cu-SSZ-13?

    Science.gov (United States)

    Hun Kwak, Ja; Zhu, Haiyang; Lee, Jong H; Peden, Charles H F; Szanyi, János

    2012-05-16

    H(2)-TPR and FTIR were used to characterize the nature of the Cu ions present in the Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ions at two distinct cationic positions in the SSZ-13 framework.

  19. Two different cationic positions in Cu-SSZ-13?

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Zhu, Haiyang; Lee, Jong H.; Peden, Charles HF; Szanyi, Janos

    2012-04-18

    H2-TPR and FTIR were used to characterize the Cu ions present in Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ions in two distinct cationic positions of the SSZ-13 framework.

  20. Interactions between liposomes and cations in aqueous solution.

    Science.gov (United States)

    Ruso, Juan M; Besada, Lina; Martínez-Landeira, Pablo; Seoane, Laura; Prieto, Gerardo; Sarmiento, Félix

    2003-05-01

    An investigation on the dependence of electrophoretic mobilities of unilamellar vesicles of phosphatidylcholine-cholesterol-phosphatidylinositol (PC-Chol-PI) on the concentration of several cations with variations in the relation charge/radius in the range Na+, K+, Cs+, Mg2+, Ca2+, Ba2+, Al3+, and La3+ has been realized. Plots of zeta potential against ion concentration exhibit a maximum for all the cations under study, the position of the maximum is greatly affected by the charge of the ion. From the feature of these plots two phenomenon were observed: an initial binding of cations into the slipping plane for ion concentration below the maximum and a phenomenon of vesicle association for concentration above the maximum. To confirm these observations measurements on dynamic light scattering were performed to obtain the corresponding size distribution of the liposomes at different ion concentrations. Finally the ability of the Stern isotherm to describe the adsorption of the cations to vesicles was tested by two methods. The two main parameters of the theory: the total number of adsorption sites per unit area, N1, and the equilibrium constant, K; (and consequently the free energy of adsorption, deltaG0ads) were calculated for the different ions, showing good agreement. The equilibrium constants of adsorption have been found to obey a linear relationship with ion radius the slope of which decreases with the ion charge.

  1. New cation-exchange membranes for hyperfiltration processes

    NARCIS (Netherlands)

    Velden, van der P.M.; Smolders, C.A.

    1977-01-01

    A new route for the preparation of cation exchange membranes from polystyrene-polyisoprene-polystyrene (SIS) block copolymers has been studied, using N-chlorosulfonyl isocyanate. At temperatures of 0° to 20°C, N-chlorosulfonyl isocyanate reacts readily with the olefin group in polyisoprenes, resulti

  2. Predictive model of cationic surfactant binding to humic substances

    NARCIS (Netherlands)

    Ishiguro, M.; Koopal, L.K.

    2011-01-01

    The humic substances (HS) have a high reactivity with other components in the natural environment. An important factor for the reactivity of HS is their negative charge. Cationic surfactants bind strongly to HS by electrostatic and specific interaction. Therefore, a surfactant binding model is devel

  3. Synthesis and Properties of Novel Cationic Maleic Diester Polymerizable Surfactants

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Three new cationic polymerizable surfactants are synthesized by the reaction of alkylmaleic hemiester with glycidyltrimethylammonium chloride. Their structures are confirmed by 1H NMR, IR and elements analysis. The values of CMC and gCMC of these surfactants have been measured. One can obtain nearly monodisperse polystyrene latex by emulsion polymerization using the polymerizable surfactant.

  4. Gas-phase infrared photodissociation spectroscopy of cationic polyaromatic hydrocarbons

    NARCIS (Netherlands)

    Oomens, J.; van Roij, A. J. A.; Meijer, G.; von Helden, G.

    2000-01-01

    Infrared spectra of gas-phase cationic naphthalene, phenanthrene, anthracene, and pyrene are recorded in the 500-1600 cm(-1) range using multiphoton dissociation in an ion trap. Gas-phase polyaromatic hydrocarbons are photoionized by an excimer laser and stored in a quadrupole ion trap. Subsequent i

  5. Metal Cations in G-Quadruplex Folding and Stability

    Science.gov (United States)

    Bhattacharyya, Debmalya; Mirihana Arachchilage, Gayan; Basu, Soumitra

    2016-01-01

    This review is focused on the structural and physicochemical aspects of metal cation coordination to G-Quadruplexes (GQ) and their effects on GQ stability and conformation. G-quadruplex structures are non-canonical secondary structures formed by both DNA and RNA. G-quadruplexes regulate a wide range of important biochemical processes. Besides the sequence requirements, the coordination of monovalent cations in the GQ is essential for its formation and determines the stability and polymorphism of GQ structures. The nature, location, and dynamics of the cation coordination and their impact on the overall GQ stability are dependent on several factors such as the ionic radii, hydration energy, and the bonding strength to the O6 of guanines. The intracellular monovalent cation concentration and the localized ion concentrations determine the formation of GQs and can potentially dictate their regulatory roles. A wide range of biochemical and biophysical studies on an array of GQ enabling sequences have generated at a minimum the knowledge base that allows us to often predict the stability of GQs in the presence of the physiologically relevant metal ions, however, prediction of conformation of such GQs is still out of the realm. PMID:27668212

  6. Cation Hydration Constants by Proton NMR: A Physical Chemistry Experiment.

    Science.gov (United States)

    Smith, Robert L.; And Others

    1988-01-01

    Studies the polarization effect on water by cations and anions. Describes an experiment to illustrate the polarization effect of sodium, lithium, calcium, and strontium ions on the water molecule in the hydration spheres of the ions. Analysis is performed by proton NMR. (MVL)

  7. Planar Homotropenylium Cation : A Transition State with Reversed Aromaticity

    NARCIS (Netherlands)

    Gibson, Christopher M.; Havenith, Remco W. A.; Fowler, Patrick W.; Jenneskens, Leonardus W.

    2015-01-01

    In contrast to the equilibrium structure of the homoaromatic C-s homotropenylium cation, C8H9+ (1), which supports a pinched diatropic ring current, the C(2)v transition state (2) for inversion of the methylene bridge of 1 is antiaromatic and supports a two-lobe paratropic pi current, as detected by

  8. Cationic Organic/Inorganic Hybrids and Their Swelling Properties

    Institute of Scientific and Technical Information of China (English)

    E. S. Dragan; L. Ghimici; M. Cazacu

    2005-01-01

    @@ 1Introduction Specific properties of poly(dimethylsiloxanes), such as low glass transition temperature, low surface energy, good insulating properties, biological and chemical inertness, high diffusion coefficient of gases, make them very attractive for practical applications in the daily life. However, there is a great interest last time in the preparation of ionic organic/inorganic materials with new properties for new applications. Quaternary ammonium salt(QAS) groups included in siloxane copolymers could induce new interesting properties such as:permanent fungicidal and bactericidal properties, which make them very attractive as materials for sanitary applications, improved selectivity coefficients of the gas-separation membranes, ion-exchange properties and so forth. So far, QAS groups have been located in the side chain[1,2]. Our interest was focused on the preparation of some novel cationic polysiloxane copolymers containing QAS groups of both integral type and pendent type[3,4]. Our objectives for the present study concern the synthesis of some cationic organic/siloxane hybrid materials with swelling properties controlled by both the nature of cationic organic component and the ratio between the organic and inorganic counterparts. Such cationic hybrid materials could be of interest for the preparation of new stimuli-responsive hydrogels[5,6].

  9. Cation ordering and superstructures in natural layered double hydroxides.

    Science.gov (United States)

    Krivovichev, Sergey V; Yakovenchuk, Victor N; Zolotarev, Andrey A; Ivanyuk, Gregory N; Pakhomovsky, Yakov A

    2010-01-01

    Layered double hydroxides (LDHs) constitute an important group of materials with many applications ranging from catalysis and absorption to carriers for drug delivery, DNA intercalation and carbon dioxide sequestration. The structures of LDHs are based upon double brucite-like hydroxide layers [M(2+)(n)M(3+)(m)(OH)(2(m+n)](m+), where M(2+) = Mg(2+), Fe(2+), Mn(2+), Zn(2+), etc.; M(3+) = Al(3+), Fe(3+), Cr(3+), Mn(3+), etc. Structural features of LDHs such as cation ordering, charge distribution and polytypism have an immediate influence upon their properties. However, all the structural studies on synthetic LDHs deal with powder samples that prevent elucidation of such fine details of structure architecture as formation of superstructures due to cation ordering. In contrast to synthetic materials, natural LDHs are known to form single crystals accessible to single-crystal X-ray diffraction analysis, which provides a unique possibility to investigate 3D cation ordering in LDHs that results in formation of complex superstructures, where 2D cation order is combined with a specific order of layer stacking (polytypism). Therefore LDH minerals provide an indispensable source of structural information for modeling of structures and processes happening in LDHs at the molecular and nanoscale levels.

  10. Cationic amphiphiles as delivery system for genes into eukaryotic cells

    NARCIS (Netherlands)

    Oberle, Volker; Zuhorn, Inge S.; Audouy, Sandrine; Bakowsky, Udo; Smisterová, Jarmila; Engberts, Jan B.F.N.; Hoekstra, Dick; Gregoriadis, G; McCormack, B

    2000-01-01

    Cationic liposomes, consisting of synthetic amphiphiles and a so-called helper lipid, rapidly form complexes with DNA, known as lipoplexes. When incubated with cells in culture, the DNA can be delivered into the cell and becomes expressed. Because of these properties, lipoplexes are considered a use

  11. Inward Cationic Diffusion and Percolation Transition in Glass-Ceramics

    DEFF Research Database (Denmark)

    Smedsklaer, Morten Mattrup; Yue, Yuanzheng; Mørup, Steen

    2010-01-01

    of crystallization. Below the critical value, the diffusion extent decreases only slightly with the degree of crystallization. No cationic diffusion is observed in the fully crystalline materials. The critical value might be associated with a percolation transition from an interconnected to a disconnected glass...

  12. Cationic starches on cellulose surfaces. A study of polyelectrolyte adsorption.

    NARCIS (Netherlands)

    Steeg, van de H.G.M.

    1992-01-01

    Cationic starches are used on a large scale in paper industry as wet-end additives. They improve dry strength. retention of fines and fillers, and drainage. Closure of the white water systems in the paper mills hase increased the concentration of detrimental substances. This might be the reason for

  13. Analysis of Adsorption, Ion Exchange, Thermodynamic Behaviour of Some Organic Cations on Dowex 50WX4-50/H+ Cation Exchanger in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Ehteram A. Noor

    2011-01-01

    Full Text Available The equilibrium adsorption, ion exchange characteristics of various concentrations of some organic cations from aqueous solutions onto dowex 50WEX/H+ cation exchanger were studied at different temperatures in the range of 30-50 °C. The studied cations showed good adsorptive properties onto dowex 50WX4-5/H+ at different concentrations and temperatures. Main adsorption behaviour was ion exchange between hydrogen ions and the organic cations as indicated from the linear relation between the initial concentration of the organic cations and the released hydrogen ions. It was found that the adsorption affinity of dowex 50WX4-50/H+ towards the studied organic cations depends on the substituent type of the organic cations giving the following increasing order: 1-H < 2-OH < 3-OCH3. Thermodynamic parameters for the adsorption of the studied organic cations were evaluated and discussed. It was found that the adsorption 1-H organic cation was spontaneous, ordered, exothermic and favored with decreasing temperature. On the other hand the adsorption of both 2-OH and 3-OCH3 organic cations was found to be spontaneous and disordered with enthalpy change varies significantly with increasing organic cation concentration, suggesting dipole-dipole adsorption forces as new active sites for adsorption under conditions of relatively high concentrations. Freundlich and Dubinin-Radushkevich adsorption isotherm models reasonably describe the adsorption of the studied organic cations onto dowex 50WX4-50/H+ by segmented straight lines depending on the studied range of concentration, indicating the existence of two different sets of adsorption sites with substantial difference in energy of adsorption. According to Dubinin-Radushkevich adsorption isotherm model, physical-ion exchange mechanism was suggested for the adsorption of 1-H organic cation and both physical and chemical-ion exchange mechanisms were suggested for the adsorption of 2-OH and 3-OCH3 organic cations

  14. Influence of various functional groups on the relative stability of alkylperoxy triplet cations: A theoretical study

    Science.gov (United States)

    Smith, Kenneth J.; Meloni, Giovanni

    2015-07-01

    CBS-QB3 energy calculations show that the formation of a stable triplet cation for alkylperoxy radicals is dependent on factors other than the stability of the daughter cations exclusively. We have found that in cases where the daughter ions are not capable of stabilizing the cation through hyperconjugation, it is possible for the triplet cation to be bound. In many circumstances, CBS-QB3 calculations have found bound triplet cation states with 'negative dissociation energies.' These results are attributed to the effects that electron donating/withdrawing substituents have on the spin and charge densities of the resulting cations.

  15. Photo-fragmentation spectroscopy of benzylium and 1-phenylethyl cations

    Energy Technology Data Exchange (ETDEWEB)

    Féraud, Géraldine; Dedonder-Lardeux, Claude; Jouvet, Christophe, E-mail: christophe.jouvet@univ-amu.fr [Physique des Interactions Ioniques et Moleculaires, UMR CNRS 7345, Aix-Marseille Université, Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20 (France); Soorkia, Satchin [Institut des Sciences Moléculaires d’Orsay, CNRS UMR 8214, Université Paris Sud 11, 91405 Orsay Cedex (France)

    2014-01-14

    The electronic spectra of cold benzylium (C{sub 6}H{sub 5}-CH{sub 2}{sup +}) and 1-phenylethyl (C{sub 6}H{sub 5}-CH-CH{sub 3}{sup +}) cations have been recorded via photofragment spectroscopy. Benzylium and 1-phenylethyl cations produced from electrosprayed benzylamine and phenylethylamine solutions, respectively, were stored in a cryogenically cooled quadrupole ion trap and photodissociated by an OPO laser, scanned in parts of the UV and visible regions (600–225 nm). The electronic states and active vibrational modes of the benzylium and 1-phenylethyl cations as well as those of their tropylium or methyl tropylium isomers have been calculated with ab initio methods for comparison with the spectra observed. Sharp vibrational progressions are observed in the visible region while the absorption features are much broader in the UV. The visible spectrum of the benzylium cation is similar to that obtained in an argon tagging experiment [V. Dryza, N. Chalyavi, J. A. Sanelli, and E. J. Bieske, J. Chem. Phys. 137, 204304 (2012)], with an additional splitting assigned to Fermi resonances. The visible spectrum of the 1-phenylethyl cation also shows vibrational progressions. For both cations, the second electronic transition is observed in the UV, around 33 000 cm{sup −1} (4.1 eV) and shows a broadened vibrational progression. In both cases the S{sub 2} optimized geometry is non-planar. The third electronic transition observed around 40 000 cm{sup −1} (5.0 eV) is even broader with no apparent vibrational structures, which is indicative of either a fast non-radiative process or a very large change in geometry between the excited and the ground states. The oscillator strengths calculated for tropylium and methyl tropylium are weak. Therefore, these isomeric structures are most likely not responsible for these absorption features. Finally, the fragmentation pattern changes in the second and third electronic states: C{sub 2}H{sub 2} loss becomes predominant at higher

  16. Solubilization of pentanol by cationic surfactants and binary mixtures of cationic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, M.E.

    1993-12-31

    The research reported here has included studies of the solubilization of pentanol in hexadecylpyridinium chloride (CPC), trimethyletetradecylammonium chloride (C{sub 14}Cl), benzyldimethyltetradecylammonium chloride (C{sub 14}BzCl), benzyldimethylhexadecylpyridinium chloride (C{sub 16}BzCl), hexadecyltrimethylammonium bromide (CTAB), and binary mixtures of CPC + C{sub 16}BzCl and C{sub 14}Cl + C{sub 14}BzCl. Rather than using calorimetric methods, this project will employ headspace chromatography to measure solubilization of pentanol over a wide range of solute concentrations. While not yielding as much thermodynamic data as calorimetry, headspace chromatography is a more direct measure of the extent of solubilization. Using headspace chromatography, is a more direct measure of the extent of solubilization. Using headspace chromatography, this study will seek to determine whether strongly synergistic mixture ratios exist in the case of binary cationic surfactant systems. There are two equilibria in the pentanol-water-surfactant system: (1) The pentanol solubilized in micelles is in equilibrium with the monomeric pentanol in solution, and (2) the monomeric pentanol is in equilibrium with the pentanol in the vapor above the solution. To establish the link between the two equilibria, a sample of the vapor above pure liquid pentanol must be collected, in order to find the activity of pentanol in solution. Also, a calibration curve for various concentrations of pentanol in solution. From this type of data it is possible to infer both the concentration of pentanol solubilized in micelles and the concentrations of pentanol in the ``bulk`` solution outside the micelles. The method is equally applicable to systems containing a single surfactant as well as mixtures of surfactants.

  17. Measuring cation dependent DNA polymerase fidelity landscapes by deep sequencing.

    Directory of Open Access Journals (Sweden)

    Bradley Michael Zamft

    Full Text Available High-throughput recording of signals embedded within inaccessible micro-environments is a technological challenge. The ideal recording device would be a nanoscale machine capable of quantitatively transducing a wide range of variables into a molecular recording medium suitable for long-term storage and facile readout in the form of digital data. We have recently proposed such a device, in which cation concentrations modulate the misincorporation rate of a DNA polymerase (DNAP on a known template, allowing DNA sequences to encode information about the local cation concentration. In this work we quantify the cation sensitivity of DNAP misincorporation rates, making possible the indirect readout of cation concentration by DNA sequencing. Using multiplexed deep sequencing, we quantify the misincorporation properties of two DNA polymerases--Dpo4 and Klenow exo(---obtaining the probability and base selectivity of misincorporation at all positions within the template. We find that Dpo4 acts as a DNA recording device for Mn(2+ with a misincorporation rate gain of ∼2%/mM. This modulation of misincorporation rate is selective to the template base: the probability of misincorporation on template T by Dpo4 increases >50-fold over the range tested, while the other template bases are affected less strongly. Furthermore, cation concentrations act as scaling factors for misincorporation: on a given template base, Mn(2+ and Mg(2+ change the overall misincorporation rate but do not alter the relative frequencies of incoming misincorporated nucleotides. Characterization of the ion dependence of DNAP misincorporation serves as the first step towards repurposing it as a molecular recording device.

  18. Measurement of antioxidant activity with trifluoperazine dihydrochloride radical cation

    Directory of Open Access Journals (Sweden)

    M.N. Asghar

    2008-06-01

    Full Text Available A novel, rapid and cost-effective trifluoperazine dihydrochloride (TFPH decolorization assay is described for the screening of antioxidant activity. A chromogenic reaction between TFPH and potassium persulfate at low pH produces an orange-red radical cation with maximum absorption at 502 nm in its first-order derivative spectrum. TFPH was dissolved in distilled water to give a 100 mM solution. The TFPH radical cation solution was made by reacting 0.5 mL of the solution with K2S2O8 (final concentration: 0.1 mM and diluting to 100 mL with 4 M H2SO4 solution. A linear inhibition of color production was observed with linearly increasing amounts of antioxidants, with correlation coefficients (R² ranging from 0.999 to 0.983. The antioxidant capacity of standard solutions of an antioxidant was evaluated by comparing with the inhibition curve using Trolox as the standard. Comparison of antioxidant capacity determined with this newly developed TFPH assay and with the well-known 2,2'-azinobis-[3-ethylbenzthiazoline-6-sulfonic acid] (ABTS-persulfate decolorization assay indicated the efficacy and sensitivity of the procedure. The proposed assay is less expensive (costs about US$4 per 100 assays and requires only 20 min for preparation of radical cation solution in comparison with ABTS assay, in which almost 12-16 h are required for preparation of a stable ABTS radical cation solution. The present assay has the advantage over ABTS assay that it can be used to measure the antioxidant activity of the samples, which are naturally found at a pH as low as 1, because the radical cation itself has been stabilized at low pH.

  19. IR spectroscopy of cationized aliphatic amino acids: Stability of charge-solvated structure increases with metal cation size

    NARCIS (Netherlands)

    Drayss, M. K.; Armentrout, P. B.; Oomens, J.; Schaefer, M.

    2010-01-01

    Gas-phase structures of alkali metal cationized (Li+, Na+,K+, Rb+, and Cs+) proline (Pro) and N-methyl alanine have been investigated using infrared multiple photon dissociation (IRMPD) spectroscopy utilizing light generated by a free electron laser and computational modeling. Measured IRMPD spectra

  20. IR spectroscopy of cationized aliphatic amino acids: Stability of charge-solvated structure increases with metal cation size

    NARCIS (Netherlands)

    Drayß, M.K.; Armentrout, P.B.; Oomens, J.; Schäfer, M.

    2010-01-01

    Gas-phase structures of alkali metal cationized (Li+, Na+, K+, Rb+, and Cs+) proline (Pro) and N-methyl alanine have been investigated using infrared multiple photon dissociation (IRMPD) spectroscopy utilizing light generated by a free electron laser and computational modeling. Measured IRMPD spectr

  1. Variational first hyperpolarizabilities of 2,3-naphtho-15-crown-5 ether derivatives with cation-complexing: a potential and selective cation detector.

    Science.gov (United States)

    Yu, Hai-Ling; Wang, Wen-Yong; Hong, Bo; Zong, Ying; Si, Yan-Ling; Hu, Zhong-Qiang

    2016-09-29

    Crown ethers, as a kind of heterocycle, have been the subject of great interest over recent decades due to their selective capability to bind to metal cations. The use of a constant crown ether, such as naphtho-15-crown-5 (N15C5), and varied metal cations (Li(+), Na(+), K(+), Be(2+), Mg(2+), Ca(2+), Co(2+), Ni(2+), Cu(2+)) makes it possible to determine the contributions of the metal cations to nonlinear optical (NLO) responses and to design an appropriate NLO-based cation detector. N15C5 and its metal cation derivatives have been systematically investigated by density functional theory. It is found that the dependency of the first hyperpolarizability relies on the metal cation, especially for transition metals. The decrease of the first hyperpolarizabilities for alkali metal cation derivatives is due to their relatively low oscillator strengths, whereas the significant increase of the first hyperpolarizabilities for transition metal cation derivatives can be further illustrated by their low transition energies, large amplitudes and separate distributions of first hyperpolarizability density. Thus, the alkali metal and transition metal cations are distinguishable and the transition metal cations are easier to detect by utilizing the variations in NLO responses.

  2. Pharmacology of the human cell voltage-dependent cation channel. Part II: inactivation and blocking

    DEFF Research Database (Denmark)

    Bennekou, Poul; Barksmann, Trine L.; Kristensen, Berit I.

    2004-01-01

    Human red cells; Nonselective voltage-dependent cation channel; NSVDC channel; Thiol group reagents......Human red cells; Nonselective voltage-dependent cation channel; NSVDC channel; Thiol group reagents...

  3. 21 CFR 872.3420 - Carboxymethylcellulose sodium and cationic polyacrylamide polymer denture adhesive.

    Science.gov (United States)

    2010-04-01

    ... polyacrylamide polymer denture adhesive. 872.3420 Section 872.3420 Food and Drugs FOOD AND DRUG ADMINISTRATION....3420 Carboxymethylcellulose sodium and cationic polyacrylamide polymer denture adhesive. (a) Identification. A carboxymethylcellulose sodium and cationic polyacrylamide polymer denture adhesive is a...

  4. Preparing cationic cotton linter cellulose with high substitution degree by ultrasonic treatment.

    Science.gov (United States)

    Zhang, Fulong; Pang, Zhiqiang; Dong, Cuihua; Liu, Zong

    2015-11-05

    As an important cellulose derivative, cationic cellulose has becoming an attractive material. However, it remains challenging to produce cationic cellulose with high substitute degree. In this paper, we successfully increased the substitute degree of cationic cellulose by introducing ultrasonic treatment, which efficiently breaks hydrogen bonds of the chemical structure of cationic cellulose. Properties of cationic cellulose were studied by scanning electron spectroscope (SEM), contact angle, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Experimental results show that the cationic cellulose has rougher surface and lower crystallinity degree as compared to the original sample. TGA analysis verifies that the thermostability of CLC decreases after the cationic modification. The residual of the cationic cellulose (25 wt%) after pyrolysis increases significantly as compared to that of the original cellulose (15 wt%).

  5. Comparison of cation adsorption by isostructural rutile and cassiterite.

    Energy Technology Data Exchange (ETDEWEB)

    Machesky, M.; Wesolowski, D.; Rosenqvist, J.; Predota, M.; Vlcek, L.; Ridley, M.; Kohli, V.; Zhang, Z.; Fenter, P.; Cummings, P.; Lvov, S.; Fedkin, M.; Rodriguez-Santiago, V.; Kupicki, J.; Bandura, A. (X-Ray Science Division); (Illinois State Water Survey); (Oak Ridge National Laboratory); (University of South Branisovska); (Texas Tech University); (Vanderbilt University); (The Pennsylvania State University); (St. Petersburg State University)

    2011-01-01

    Macroscopic net proton charging curves for powdered rutile and cassiterite specimens with the (110) crystal face predominant, as a function of pH in RbCl and NaCl solutions, trace SrCl{sub 2} in NaCl, and trace ZnCl{sub 2} in NaCl and Na Triflate solutions, are compared to corresponding molecular-level information obtained from static DFT optimizations and classical MD simulations, as well as synchrotron X-ray methods. The similarities and differences in the macroscopic charging behavior of rutile and cassiterite largely reflect the cation binding modes observed at the molecular level. Cation adsorption is primarily inner-sphere on both isostructural (110) surfaces, despite predictions that outer-sphere binding should predominate on low bulk dielectric constant oxides such as cassiterite ({epsilon}{sub bulk} {approx} 11). Inner-sphere adsorption is also significant for Rb{sup +} and Na{sup +} on neutral surfaces, whereas Cl{sup -} binding is predominately outer-sphere. As negative surface charge increases, relatively more Rb{sup +}, Na{sup +}, and especially Sr{sup 2+} are bound in highly desolvated tetradentate fashion on the rutile (110) surface, largely accounting for enhanced negative charge development relative to cassiterite. Charging curves in the presence of Zn{sup 2+} are very steep but similar for both oxides, reflective of Zn{sup 2+} hydrolysis (and accompanying proton release) during the adsorption process, and the similar binding modes for ZnOH{sup +} on both surfaces. These results suggest that differences in cation adsorption between high and low bulk dielectric constant oxides are more subtly related to the relative degree of cation desolvation accompanying inner-sphere binding (i.e., more tetradentate binding on rutile), rather than distinct inner- and outer-sphere adsorption modes. Cation desolvation may be favored at the rutile (110) surface in part because inner-sphere water molecules are bound further from and less tightly than on the

  6. Star-like superalkali cations featuring planar pentacoordinate carbon.

    Science.gov (United States)

    Guo, Jin-Chang; Tian, Wen-Juan; Wang, Ying-Jin; Zhao, Xue-Feng; Wu, Yan-Bo; Zhai, Hua-Jin; Li, Si-Dian

    2016-06-28

    Superalkali cations, known to possess low vertical electron affinities (VEAs), high vertical detachment energies, and large highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps, are intriguing chemical species. Thermodynamically, such species need to be the global minima in order to serve as the promising targets for experimental realization. In this work, we propose the strategies of polyhalogenation and polyalkalination for designing the superalkali cations. By applying these strategies, the local-minimum planar pentacoordinate carbon (ppC) cluster CBe5 can be modified to form a series of star-like superalkali ppC or quasi-ppC CBe5X5 (+) (X = F, Cl, Br, Li, Na, K) cations containing a CBe5 moiety. Polyhalogenation and polyalkalination on the CBe5 unit may help eliminate the high reactivity of bare CBe5 molecule by covering the reactive Be atoms with noble halogen anions and alkali cations. Computational exploration of the potential energy surfaces reveals that the star-like ppC or quasi-ppC CBe5X5 (+) (X = F, Cl, Br, Li, Na, K) clusters are the true global minima of the systems. The predicted VEAs for CBe5X5 (+) range from 3.01 to 3.71 eV for X = F, Cl, Br and 2.12-2.51 eV for X = Li, Na, K, being below the lower bound of the atomic ionization potential of 3.89 eV in the periodic table. Large HOMO-LUMO energy gaps are also revealed for the species: 10.76-11.07 eV for X = F, Cl, Br and 4.99-6.91 eV for X = Li, Na, K. These designer clusters represent the first series of superalkali cations with a ppC center. Bonding analyses show five Be-X-Be three-center two-electron (3c-2e) σ bonds for the peripheral bonding, whereas the central C atom is associated with one 6c-2e π bond and three 6c-2e σ bonds, rendering (π and σ) double aromaticity. Born-Oppenheimer molecular dynamics simulations indicate that the CBe5 motif is robust in the clusters. As planar hypercoordination carbon species are often thermodynamically

  7. Diffusion of an organic cation into root cell walls.

    Science.gov (United States)

    Meychik, N R; Yermakov, I P; Prokoptseva, O S

    2003-07-01

    Uptake of a cationic dye (methylene blue) by isolated root cell walls, roots of whole transpiring seedlings, and excised roots was investigated using 7-day-old seedlings of cucumber, maize, and wheat. The number of ionogenic groups per 1 g dry and wet weight of the root cell walls, their swelling capacity (K(cw)), time-dependence of methylene blue (M(cw)) ion exchange capacity, and diffusion coefficients of the cation diffusion in the polymer matrix of the cell walls (D(cw)) were determined. The M(cw) value depended on pH (or carboxyl group dissociation); it changed in accordance with the number of carboxyl groups per 1 g cell wall dry weight. This parameter decreased in the order: cucumber > wheat > maize. For description of experimental kinetic curves and calculation of cation diffusion coefficients, the equation for ion diffusion into a cylinder of infinite length was used. The chosen model adequately described cation diffusion in cell walls and roots. Diffusion coefficient values for cucumber, wheat, and maize were 3.1*10(-8), 1.3*10(-8), and 8.4*10(-8) cm(2)/sec, respectively. There was a statistically significant linear dependence between K(cw) and D(cw) values, which characterize the same property of the polymer matrix, rigidity of its polymer structure or the degree of cross-linkage or permeability. This also confirms the right choice of the model selected for calculation of methylene blue diffusion coefficients, because K(cw) and D(cw) values were obtained in independent experiments. The coefficients determined for methylene blue diffusion in transpiring seedling roots (D(ts)) and excised roots (D(er)) depended on the plant species. The rate of methylene blue diffusion into the excised roots was either 1.5-fold lower (cucumber) or 3-4-times lower (maize, wheat) than in cell walls. The values of diffusion coefficients in roots of whole seedlings were comparable which those for the cell walls. On the basis of the experimental data and results of calculations

  8. High performance flocculating agents based on cationic polysaccharides in relation to coal fine suspension

    Energy Technology Data Exchange (ETDEWEB)

    Pal, S.; Sen, G.; Karmakar, N.C.; Mal, D.; Singh, R.P. [Birla Institute of Technology, Ranchi (India). Dept. of Applied Chemistry

    2008-11-04

    Five polysaccharides namely amylopectin, amylose, glycogen, guar gum and starch have been cationized by grafting with N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride and studied for their flocculation behaviors. Of them, cationic glycogen (Cat Gly) is found to be the best for flocculation of coal suspended sample amongst cationic polysaccharides. Cat Gly was compared with some of the commercial flocculants.

  9. The Influence of Cationization on the Dyeing Performance of Cotton Fabrics with Direct Dyes

    Directory of Open Access Journals (Sweden)

    M. F. Shahin

    2015-08-01

    Full Text Available The effect of cationic modification of cotton fabrics, using cationic agent (Chromatech 9414 on direct dyeing characteristics was studied in this work. Cationization of cotton fabric at different conditions (pH, cationic agent concentration, temperature and time was investigated and the optimum conditions were determined . Nitrogen content of cotton samples pretreated with cationic agent was indicated. The results showed that increasing cationic agent concentration lead to higher nitrogen content on cotton fabric . The cationized cotton fabrics were dyed with two direct dyes (C.I. Direct Yellow 142 - C.I. Direct red 224 and the results were compared to untreated cotton fabrics. The parameters which may affect the dyeing process such as dye concn., addition of salt, time and temperature of dyeing were studied. The dyeing results illustrate that cationization improves the fabric dyeability compared to the uncationized cotton and the magnitude of increase in colour depth depends on the nitrogen content of the cationized cotton fabric .The results also refer to possibility of dyeing cationized cotton fabric with direct dyes without addition of electrolytes to give colour strength higher than that achieved on uncationized cotton using conventional dyeing method .Another important advantage of cationic treatment is in the saving of dye concn., energy ,dyeing time , rinse water and subsequently saving of waste water treatment , and finally minimizes the environmental pollution . The changes in surface morphology of fibres after cationization were identified by various methods such as wettability and scanning with the electron microscope. Different fastness properties were evaluated.

  10. 21 CFR 872.3480 - Polyacrylamide polymer (modified cationic) denture adhesive.

    Science.gov (United States)

    2010-04-01

    ... adhesive. 872.3480 Section 872.3480 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... polymer (modified cationic) denture adhesive. (a) Identification. A polyacrylamide polymer (modified cationic) denture adhesive is a device composed of polyacrylamide polymer (modified cationic) intended...

  11. Structure of ionic liquids with cationic silicon-substitutions

    Science.gov (United States)

    Wu, Boning; Shirota, Hideaki; Lall-Ramnarine, Sharon; Castner, Edward W.

    2016-09-01

    Significantly lower viscosities result when a single alkyl carbon is replaced by a silicon atom on the side chain of an ionic liquid cation. To further explore this effect, we compare liquid structure factors measured using high-energy X-ray scattering and calculated using molecular dynamics simulations. Four ionic liquids are studied that each has a common anion, bis(trifluoromethylsulfonyl)amide ( NTf2 - ). The four cations for this series of NTf2 - -anion ionic liquids are 1-methyl-3-trimethylsilylmethylimidazolium (Si-mim+), 1-methyl-3-neopentylimidazolium (C-mim+), 1-methyl-3-pentamethyldisiloxymethylimidazolium (SiOSi-mim+), and 1-methyl-1-trimethylsilylmethylpyrrolidinium (Si-pyrr+). To achieve quantitative agreement between the structure factors measured using high-energy X-ray scattering and molecular dynamics simulations, new transferable parameters for silicon were calibrated and added to the existing force fields.

  12. Review on cation exchange selectivity coefficients for MX-80 bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Domenech, C.; Arcos, D.; Duro, L. [ENVIROS, Passeig de Rubi, 29-31, 08197 Valldoreix (Spain); Sellin, P. [SKB, Brahegatan 47, SE-102 40 Stockholm (Sweden)

    2005-07-01

    Full text of publication follows: Bentonite is considered as engineered barrier in the near field of a nuclear waste repository due to its low permeability, what impedes groundwater flow to the nuclear waste, and its high retention capacity (sorption) of radionuclides in the eventuality of groundwater intrusion. One of the main retention processes occurring at the bentonite surface is ion exchange. This process may exert a strong control on the mobility of major pore water cations. Changes in major cation concentration, especially calcium, can affect the dissolution-precipitation of calcite, which in turn controls one of the key parameters in the system: pH. The cation exchange process is usually described according to the Gaines-Thomas convention: Ca{sup 2+} + 2 NaX = CaX{sub 2} + 2 Na{sup +}, K{sub Ca} = (N{sub Ca} x a{sup 2}{sub Na{sup +}})/(N{sup 2}{sub Na} x a{sub Ca{sup 2+}}) where K{sub Ca} is the selectivity coefficient for the Ca by Na exchange, ai is the activity of cation 'i' in solution and NJ the equivalent fractional occupancy of cation 'J' in bentonite. Parameters such as solid to liquid (S:L) ratio and dry density of the solid have an important influence on the value of selectivity coefficients (K{sub ex}). Although in most geochemical modelling works, K{sub ex} values are directly taken from experiments conducted at low S:L ratios and low dry densities, the expected conditions in a deep geological nuclear waste repository are higher S:L and higher bentonite density (1.6 g.cm{sup -3} in the SKB design to obtain a fully water saturated density of around 2.0 g.cm{sup -3}). Experiments focused at obtaining selectivity coefficients under the conditions of interest face the difficulty of achieving a proper extraction and analyses of pore water without disturbing the system by the sampling method itself. In this work we have conducted a complete analyses of published data on MX-80 bentonite cationic exchange in order to assess the

  13. S. Typhimurium strategies to resist killing by cationic antimicrobial peptides.

    Science.gov (United States)

    Matamouros, Susana; Miller, Samuel I

    2015-11-01

    S. Typhimurium is a broad host range Gram-negative pathogen that must evade killing by host innate immune systems to colonize, replicate, cause disease, and be transmitted to other hosts. A major pathogenic strategy of Salmonellae is entrance, survival, and replication within eukaryotic cell phagocytic vacuoles. These phagocytic vacuoles and gastrointestinal mucosal surfaces contain multiple cationic antimicrobial peptides (CAMPs) which control invading bacteria. S. Typhimurium possesses several key mechanisms to resist killing by CAMPs which involve sensing CAMPs and membrane damage to activate signaling cascades that result in remodeling of the bacterial envelope to reduce its overall negative charge with an increase in hydrophobicity to decrease binding and effectiveness of CAMPs. Moreover Salmonellae have additional mechanisms to resist killing by CAMPs including an outer membrane protease which targets cationic peptides at the surface, and specific efflux pumps which protect the inner membrane from damage. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.

  14. Preparation of sulfonated cation exchangers from petroleum asphaltites

    Energy Technology Data Exchange (ETDEWEB)

    Pokonova, Yu.V.; Pol' kin, G.B.; Proskuryakov, V.A.

    1980-01-01

    It was established that the reaction of petroleum asphaltite sulfonation is determined in the first step by the chemical reaction rate, and in the last --- by diffusion factors. The kinetic constants were found for each reaction step. Sulfonated cation exchangers were obtained having the characteristics: specific volume of the swollen cation exchanger 3.30 mL/g, bulk density of the air-dry product 0.58 g/mL., moisture content 23.4%, swelling in water 41.6%, mechanical strength 80.0%, static exchange capacity with respect to 0.1N NaOH solution 2.76 mg equiv/g, dynamic exchange capacity with respect to 0.0035N CaC1/sub 2/ solution for a specific load of 10 L/L.h 465 mg equiv/L.

  15. Cationic polymers for successful flocculation of marine microalgae.

    Science.gov (United States)

    't Lam, G P; Vermuë, M H; Olivieri, G; van den Broek, L A M; Barbosa, M J; Eppink, M H M; Wijffels, R H; Kleinegris, D M M

    2014-10-01

    Flocculation of microalgae is a promising technique to reduce the costs and energy required for harvesting microalgae. Harvesting marine microalgae requires suitable flocculants to induce the flocculation under marine conditions. This study demonstrates that cationic polymeric flocculants can be used to harvest marine microalgae. Different organic flocculants were tested to flocculate Phaeodactylum tricornutum and Neochloris oleoabundans grown under marine conditions. Addition of 10 ppm of the commercial available flocculants Zetag 7557 and Synthofloc 5080H to P. tricornutum showed a recovery of, respectively, 98% ± 2.0 and 94% ± 2.9 after flocculation followed by 2h sedimentation. Using the same flocculants and dosage for harvesting N. oleoabundans resulted in a recovery of 52% ± 1.5 and 36% ± 11.3. This study shows that cationic polymeric flocculants are a viable option to pre-concentrate marine cultivated microalgae via flocculation prior to further dewatering.

  16. Mobility of alkali cations in polypyrrole-dodecyl sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Kupila, E.L. [Department of Chemistry, University of Turku, 20500 Turku (Finland); Kankare, J. [Department of Chemistry, University of Turku, 20500 Turku (Finland)

    1995-03-01

    Due to the immobility of the large dodecyl sulfate anion, the mobile ions in polypyrrole-dodecyl sulfate are small ions from the solution. Virgin PP-dodecyl sulfate does not contain other ionic species, but already the first reduction causes the incorporation of cations into the membrane. Using in situ AC conductimetry on a double-band platinum electrode, we show that the insertion of cations from the solution into the PP membrane proceeds as a non-conducting zone advancing from the solution interface toward the substrate. The model allows to estimate ion mobilities in the membrane giving 8.6x10{sup -7}cm{sup 2}s{sup -1}V{sup -1} for K{sup +}. (orig.)

  17. Structure of heavy cation molecules: from experiment to simulation

    Energy Technology Data Exchange (ETDEWEB)

    Den Auwer, C.; Fillaux, C.; Guilbaud, P.; Guillaumont, D.; Moisy, P. [CEA Marcoule DEN/DRCP/SCPS, 30207 Bagnols sur Ceze (France); Conradson, S.D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Di Giandomenico, V.; Le Naour, C.; Simoni, E. [IPN Orsay, 91405 Orsay (France); Hennig, C. [Forschungszentrum Rossendorf, ROBL at ESRF, 38043 Grenoble (France)

    2008-07-01

    For industrial, environmental and public health purposes, actinide chemistry has been the subject of considerable efforts since the 50's. Aqueous redox chemistry, ionic selective recognition, uptake by specific biomolecules or compartments of the geosphere are some of the major fields of investigation. The physical-chemical properties of the actinide elements strongly depend on the 5f/6d electronic configuration. X-ray photons are an ideal spectroscopic tool for structure and bonding in actinide molecules. At high photon energies, actinide Extended X-ray Absorption Fine Structure (EXAFS) is a structural probe of the cation coordination sphere. Furthermore, coupling EXAFS with molecular dynamics or quantum chemical calculations leads to a better description of the 'cation in its close environment', like polyhedron, disorder, solvent effects etc.. (authors)

  18. Microstructure characterization and cation distribution of nanocrystalline cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Y.M., E-mail: ymabbas@live.com [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Mansour, S.A.; Ibrahim, M.H. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Ali, Shehab E., E-mail: shehab_physics@yahoo.com [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt)

    2011-11-15

    Nanocrystalline cobalt ferrite has been synthesized using two different methods: ceramic and co-precipitation techniques. The nanocrystalline ferrite phase has been formed after 3 h of sintering at 1000 deg. C. The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction and the Rietveld method. The refinement result showed that the type of the cationic distribution over the tetrahedral and octahedral sites in the nanocrystalline lattice is partially an inverse spinel. The transmission electronic microscope analysis confirmed the X-ray results. The magnetic properties of the samples were characterized using a vibrating sample magnetometer. - Highlights: > The refinement result showed that the cationic distribution over the sites in the lattice is partially an inverse spinel. > The transmission electronic microscope analysis confirmed the X-ray results. > The magnetic properties of the samples were characterized using a vibrating sample magnetometer.

  19. Sulfonated polyvinyl chloride fibers for cation-exchange microextraction.

    Science.gov (United States)

    Xu, Li; Lee, Hian Kee

    2009-09-18

    Polyvinyl chloride (PVC) fiber was derivatized by concentrated sulfuric acid to yield sulfonated PVC (PVC-SO3H). The PVC-SO3H fiber had dual properties as a sorbent, based on cation-exchange and hydrophobicity. In the present study, the novel fiber was used directly as an individual device for extraction purposes in the cation-exchange microextraction of anaesthetics, followed by high-performance liquid chromatography-UV analysis. The results demonstrated that this PVC-SO3H fiber-based microextraction afforded convenient operation and cost-effective application to basic analytes. The limits of detection for four anaesthetics ranged from 1.2 to 6.0 ng/mL. No carryover (because of its disposable usage), and no loss of sorbent phase (which normally occurs in stir-bar sorptive extraction) during extraction were observed.

  20. The effect of external divalent cations on spontaneous non-selective cation channel currents in rabbit portal vein myocytes.

    Science.gov (United States)

    Albert, A P; Large, W A

    2001-10-15

    1. The effects of external divalent cations on spontaneous single non-selective cation channel currents were studied in outside-out patches from rabbit portal vein smooth muscle cells in K+-free conditions. 2. In an external medium containing 1.5 mM Ca2+ (Ca2+o) the majority of spontaneous channel currents had a unitary conductance of 23 pS, reversal potential (Vr) of +10 mV and a low open probability (Po) at negative patch potentials. Some channels opened to a lower conductance state of about 13 pS suggesting that the cation channels have two conductance states. Open time and burst duration distributions could both be described by two exponentials with time constants of about of 1 ms and 7 ms for open times and 3 ms and 16 ms for burst durations. 3. In 0 Ca2+o the majority of spontaneous cation channels had a unitary conductance of 13 pS and Vr was shifted to +4 mV. Moreover the longer open time and longer burst duration time constants were both reduced to approximately half the values in 1.5 mM Ca2+o. 4. Compared to 0 Ca2+o the single channel currents in 3 microM and 100 microM Ca2+o had a 5- to 6-fold increase in Po which was accompanied by increases in both open times and burst durations. In 3 microM and 100 microM Ca2+o the unitary conductance of the single channel currents was between 22 and 26 pS. 5. At positive membrane potentials the single channel currents had an increased Po compared to negative potentials which was associated with increased open times and burst durations but these values were similar in 3 microM, 100 microM and 1.5 mM Ca2+o. 6. In 1.5 mM Sr2+o and 1.5 mM Ba2+o channels opened to the higher conductance state of about 22-25 pS and had a 3- to 7-fold greater Po than in 0 Ca2+o. 7. In conclusion, external divalent cations have marked effects on the unitary conductance and kinetic behaviour of non-selective cation channels in rabbit portal vein smooth muscle cells.

  1. Flow behaviour of gellan sol with selected cations.

    Science.gov (United States)

    Sharma, Shipra; Bhattacharya, Suvendu

    2015-02-01

    An understanding of the flow behaviour of the sols before gel formation is important for developing nutrient enriched gels. The influence of cations like CaCl2 (0.05 and 0.1 %, w/w) and FeSO4 (0.05 and 0.1 %, w/w) on the rheological properties of 1 % gellan sol (w/w) prior to gelling was investigated. The apparent viscosity, reported at a shear-rate of 100 s(-1), indicated that the gellan dispersion without any cation possessed lower values compared to other samples containing different cations. The Cross model provided the best fit (0.97 ≤ r ≤ 0.99, p ≤ 0.01) compared to moderate fitting to power law model (0.94 ≤ r ≤ 0.98). Among the different Cross model parameters, the zero-shear viscosity (ηo) increased with the addition of CaCl2 and FeSO4, and with an increase in their concentrations. Zero-shear viscosity values were 0.46 Pas for gellan sol, 0.79 Pas for gellan with 0.05 % (w/w) CaCl2, 1.41 Pas for gellan with 0.1 % CaCl2, 3.85 Pas for gellan with 0.05 % FeSO4 and 4.33 Pas for gellan with 0.1 % FeSO4. An increase in cation concentration from 0.05 to 0.10 % (w/w) marginally increased the relaxation time (λ) values indicating the development of more solid characteristics in the sol.

  2. Identification of bilinear systems using differential evolution algorithm

    Indian Academy of Sciences (India)

    Saban Ozer; Hasan Zorlu

    2011-06-01

    In this work, a novel identification method based on differential evolution algorithm has been applied to bilinear systems and its performance has been compared to that of genetic algorithm. Box–Jenkins system and different type bilinear systems have been identified using differential evolution and genetic algorithms. The simulation results have shown that bilinear systems can be successfully and efficiently identified using these algorithms.

  3. A NEW METHOD TO SYNTHESIZE THE CATIONIC GRAFT STARCH

    Institute of Scientific and Technical Information of China (English)

    LinLi; BingyueLiu; YafengCao

    2004-01-01

    The cationic graft copolymer was synthesized byreversed phase emulsion copolymerization of starchwith diallydimethyl ammoniumlchlorid (DADMAC)and acrylamide (AM). The copolymerization wascarried out using (NH4)2S2Os-NH2CONH2 redox asinitiator and selecting Span-20 as emulsifier. Theeffects of emulsifier content in oil phase, volumeratio of oil to water, initiator concentration and moleratio of DADMAC to AM on the graftcopolymerization were discussed. The optimumcondition of synthetics was found with theorthogonal test method.

  4. Natural zeolite reactivity towards ozone: The role of compensating cations

    Energy Technology Data Exchange (ETDEWEB)

    Valdes, Hector, E-mail: hvaldes@ucsc.cl [Laboratorio de Tecnologias Limpias (F. Ingenieria), Universidad Catolica de la Santisima Concepcion, Alonso de Ribera 2850, Concepcion (Chile); Alejandro, Serguei; Zaror, Claudio A. [Departamento de Ingenieria Quimica (F. Ingenieria), Universidad de Concepcion, Concepcion (Chile)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Chemical and thermal treatment enhances catalytic activity of natural zeolite. Black-Right-Pointing-Pointer Modified natural zeolite exhibits high stability after thermal treatment. Black-Right-Pointing-Pointer Reducing the compensating cation content leads to an increase on ozone abatement. Black-Right-Pointing-Pointer Surface active atomic oxygen was detected using the DRIFT technique. Black-Right-Pointing-Pointer The highest reactivity toward ozone was performed by NH4Z3 zeolite sample. - Abstract: Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L{sup -1}). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77 K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH{sub 3}-TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal.

  5. Electronic absorption spectrum of triacetylene cation for astronomical considerations.

    Science.gov (United States)

    Chakrabarty, S; Rice, C A; Mazzotti, F J; Dietsche, R; Maier, J P

    2013-10-03

    The A(2)Πg ← X(2)Πu electronic transition (4800-6000 Å) of triacetylene cation was measured in an ion trap, where the vibrational and rotational degrees of freedom were equilibrated to 25 K. The rotational profile of the origin band is predicted by a collisional-radiative rate model under conditions expected in diffuse interstellar clouds. Variation in the density of the surrounding gas, rotational temperature, and velocity dispersion are taken into account.

  6. THE CHARACTERISTICS OF HIGH MOLECULAR WEIGHT CATIONIC POLYACRYLAMIDE

    Institute of Scientific and Technical Information of China (English)

    Hongjie Zhang; Huiren Hu; Fushan Chen

    2004-01-01

    In this paper, the cationic polyacrylamide (CPAM)with high molecular weight was prepared in aqueous solution through a complex initiator system. The CPAM was characterized by Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance spectroscopy (13C NMR), and the charge density of the CPAM was determined by colloid titration. The results obtained indicated that the copolymerization technology used in the experiment was successful.

  7. Transformation of anthracene on various cation-modified clay minerals.

    Science.gov (United States)

    Li, Li; Jia, Hanzhong; Li, Xiyou; Wang, Chuanyi

    2015-01-01

    In this study, anthracene was employed as a probe to explore the potential catalytic effect of clay minerals in soil environment. Clay minerals saturated with various exchangeable cations were tested. The rate of anthracene transformation follows the order: Fe-smectite > Cu-smectite > Al-smectite ≈ Ca-smectite ≈ Mg-smectite ≈ Na-smectite. This suggests that transition-metal ions such as Fe(III) play an important role in anthracene transformation. Among Fe(III)-saturated clays, Fe(III)-smectite exhibits the highest catalytic activity followed by Fe(III)-illite, Fe(III)-pyrophyllite, and Fe(III)-kaolinite, which is in agreement with the interlayer Fe(III) content. Moreover, effects by two common environmental factors, pH and relative humidity (RH), were evaluated. With an increase in pH or RH, the rate of anthracene transformation decreases rapidly at first and then is leveled off. GC-MS analysis identifies that the final product of anthracene transformation is 9,10-anthraquinone, a more bioavailable molecule compared to anthracene. The transformation process mainly involves cation-π bonding, electron transfer leading to cation radical, and further oxidation by chemisorbed O2. The present work provides valuable insights into the abiotic transformation and the fate of PAHs in the soil environment and the development of contaminated land remediation technologies.

  8. Drug loading to lipid-based cationic nanoparticles

    Science.gov (United States)

    Cavalcanti, Leide P.; Konovalov, Oleg; Torriani, Iris L.; Haas, Heinrich

    2005-08-01

    Lipid-based cationic nanoparticles are a new promising option for tumor therapy, because they display enhanced binding and uptake at the neo-angiogenic endothelial cells, which a tumor needs for its nutrition and growth. By loading suitable cytotoxic compounds to the cationic carrier, the tumor endothelial and consequently also the tumor itself can be destroyed. For the development of such novel anti-tumor agents, the control of drug loading and drug release from the carrier matrix is essential. We have studied the incorporation of the hydrophobic anti-cancer agent Paclitaxel (PXL) into a variety of lipid matrices by X-Ray reflectivity measurements. Liposome suspensions from cationic and zwitterionic lipids, comprising different molar fractions of Paclitaxel, were deposited on planar glass substrates. After drying at controlled humidity, well ordered, oriented multilayer stacks were obtained, as proven by the presence of bilayer Bragg peaks to several orders in the reflectivity curves. The presence of the drug induced a decrease of the lipid bilayer spacing, and with an excess of drug, also Bragg peaks of drug crystals could be observed. From the results, insight into the solubility of Paclitaxel in the model membranes was obtained and a structural model of the organization of the drug in the membrane was derived. Results from subsequent pressure/area-isotherm and grazing incidence diffraction (GID) measurements performed with drug/lipid Langmuir monolayers were in accordance with these conjectures.

  9. Cationic porphyrin derivatives for application in photodynamic therapy of cancer

    Science.gov (United States)

    Prack McCormick, Bárbara P.; Florencia Pansa, M.; Milla Sanabria, Laura N.; Carvalho, Carla M. B.; Faustino, M. Amparo F.; Neves, Maria Graça P. M. S.; Cavaleiro, José A. S.; Rumie Vittar, Natalia B.; Rivarola, Viviana A.

    2014-04-01

    Current studies in photodynamic therapy (PDT) against cancer are focused on the development of new photosensitizers (PSs), with higher phototoxic action. The aim of this study was to compare the therapeutic efficiency of tri-cationic meso-substituted porphyrin derivatives (Tri-Py+-Me-PF, Tri-Py+-Me-Ph, Tri-Py+-Me-CO2Me and Tri-Py+-Me-CO2H) with the well-known tetra-cationic T4PM. The phototoxic action of these derivatives was assessed in human colon adenocarcinoma cells by cell viability, intracellular localization and nuclear morphology analysis. In the experimental conditions used we determined that after light activation -PF, -Ph and -CO2Me cause a more significant decline of cell viability compared to -CO2H and T4PM. These results suggest that the nature of the peripheral substituent influences the extent of cell photodamage. Moreover, we have demonstrated that PS concentration, physicochemical properties and further light activation determine the PDT response. All porphyrins were clearly localized as a punctuated pattern in the cytoplasm of the cells, and the PDT scheme resulted in apoptotic cell death after 3 h post-PDT. The tri-cationic porphyrin derivatives Tri-Py+-Me-PF, Tri-Py+-Me-Ph and Tri-Py+-Me-CO2Me showed a promising ability, making them good photosensitizer candidates for oncological PDT.

  10. Natural zeolite reactivity towards ozone: the role of compensating cations.

    Science.gov (United States)

    Valdés, Héctor; Alejandro, Serguei; Zaror, Claudio A

    2012-08-15

    Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L(-1)). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH(3)-TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal.

  11. Solidification cracking in austenitic stainless steel welds

    Indian Academy of Sciences (India)

    V Shankar; T P S Gill; S L Mannan; S Sundaresan

    2003-06-01

    Solidification cracking is a significant problem during the welding of austenitic stainless steels, particularly in fully austenitic and stabilized compositions. Hot cracking in stainless steel welds is caused by low-melting eutectics containing impurities such as S, P and alloy elements such as Ti, Nb. The WRC-92 diagram can be used as a general guide to maintain a desirable solidification mode during welding. Nitrogen has complex effects on weld-metal microstructure and cracking. In stabilized stainless steels, Ti and Nb react with S, N and C to form low-melting eutectics. Nitrogen picked up during welding significantly enhances cracking, which is reduced by minimizing the ratio of Ti or Nb to that of C and N present. The metallurgical propensity to solidification cracking is determined by elemental segregation, which manifests itself as a brittleness temperature range or BTR, that can be determined using the varestraint test. Total crack length (TCL), used extensively in hot cracking assessment, exhibits greater variability due to extraneous factors as compared to BTR. In austenitic stainless steels, segregation plays an overwhelming role in determining cracking susceptibility.

  12. Selective Facet Reactivity During Cation Exchange in Cadmium Sulfide Nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Sadtler, Bryce; Demchenko, Denis; Zheng, Haimei; Hughes, Steven; Merkle, Maxwell; Dahmen, Ulrich; Wang, Lin-Wang; Alivisatos, A. Paul

    2008-12-18

    The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for cation exchange to take place at different facets of the nanocrystal plays an important role in determining the resulting morphology of the binary heterostructure. In the case of copper I (Cu+) cation exchange in cadmium sulfide (CdS) nanorods, the reaction starts preferentially at the ends of the nanorods such that copper sulfide (Cu2S) grows inwards from either end. The resulting morphology is very different from the striped pattern obtained in our previous studies of silver I (Ag+) exchange in CdS nanorods where non-selective nucleation of silver sulfide (Ag2S) occurs. From interface formation energies calculated for several models of epitaxialconnections between CdS and Cu2S or Ag2S, we infer the relative stability of each interface during the nucleation and growth of Cu2S or Ag2S within the CdS nanorods. The epitaxial connections of Cu2S to the end facets of CdS nanorods minimize the formation energy, making these interfaces stable throughout the exchange reaction. However, as the two end facets of wurtzite CdS nanorods are crystallographically nonequivalent, asymmetric heterostructures can be produced.

  13. Naphthoxy Bounded Ferrocenium Salts as Cationic Photoinitiators for Epoxy Photopolymerization

    Directory of Open Access Journals (Sweden)

    Zh. Q. Li

    2009-01-01

    Full Text Available To improve the absorption and the bulk of arene ligands, two naphthoxy bounded ferrocenium salts as new cationic photoinitiators, (η6-α-naphthoxybenzene (η5-cyclopentadienyl iron hexafluorophosphate (NOFC-1 and (η6-β-naphthoxybenzene (η5-cyclopentadienyl iron hexafluorophosphate (NOFC-2, were synthesized, characterized, and studied. NOFC-1 and NOFC-2 were prepared by the reaction of nucleophilic substitution (SNAr with naphthol and chlorobenzene-cyclopentadienyliron salt. Their activity as cationic photoinitiators was studied using real-time infrared spectroscopy. The results obtained showed that NOFC-1 and NOFC-2 are capable of photoinitiating the cationic polymerization of epoxy monomer directly on irradiation with long-wavelength UV light (365 nm. Comparative studies also demonstrated that they exhibited better efficiency than cyclopentadienyl-Fe-cymene hexafluorophosphate (I-261. When NOFC-1 and NOFC-2 were used to efficiently initiate polymerization of epoxide, both rate of polymerization and final conversion increased using benzoyl peroxide (BPO as sensitizer. DSC studies showed that NOFC-1 and NOFC-2 photoinitiators in epoxides possess good thermal stability in the absence of light.

  14. Alkali metal cation-hexacyclen complexes: effects of alkali metal cation size on the structure and binding energy.

    Science.gov (United States)

    Austin, C A; Rodgers, M T

    2014-07-24

    Threshold collision-induced dissociation (CID) of alkali metal cation-hexacyclen (ha18C6) complexes, M(+)(ha18C6), with xenon is studied using guided ion beam tandem mass spectrometry techniques. The alkali metal cations examined here include: Na(+), K(+), Rb(+), and Cs(+). In all cases, M(+) is the only product observed, corresponding to endothermic loss of the intact ha18C6 ligand. The cross-section thresholds are analyzed to extract zero and 298 K M(+)-ha18C6 bond dissociation energies (BDEs) after properly accounting for the effects of multiple M(+)(ha18C6)-Xe collisions, the kinetic and internal energy distributions of the M(+)(ha18C6) and Xe reactants, and the lifetimes for dissociation of the activated M(+)(ha18C6) complexes. Ab initio and density functional theory calculations are used to determine the structures of ha18C6 and the M(+)(ha18C6) complexes, provide molecular constants necessary for the thermodynamic analysis of the energy-resolved CID data, and theoretical estimates for the M(+)-ha18C6 BDEs. Calculations using a polarizable continuum model are also performed to examine solvent effects on the binding. In the absence of solvent, the M(+)-ha18C6 BDEs decrease as the size of the alkali metal cation increases, consistent with the noncovalent nature of the binding in these complexes. However, in the presence of solvent, the ha18C6 ligand exhibits selectivity for K(+) over the other alkali metal cations. The M(+)(ha18C6) structures and BDEs are compared to those previously reported for the analogous M(+)(18-crown-6) and M(+)(cyclen) complexes to examine the effects of the nature of the donor atom (N versus O) and the number donor atoms (six vs four) on the nature and strength of binding.

  15. Effects of Hofmeister salt series on gluten network formation: Part I. Cation series.

    Science.gov (United States)

    Tuhumury, H C D; Small, D M; Day, L

    2016-12-01

    Different cationic salts were used to investigate the effects of the Hofmeister salt series on gluten network formation. The effects of cationic salts on wheat flour dough mixing properties, the rheological and the chemical properties of the gluten extracted from the dough with different respective salts, were investigated. The specific influence of different cationic salts on the gluten structure formation during dough mixing, compared to the sodium ion, were determined. The effects of different cations on dough and gluten of different flours mostly followed the Hofmeister series (NH4(+), K(+), Na(+), Mg(2+) and Ca(2+)). The impacts of cations on gluten structure and dough rheology at levels tested were relatively small. Therefore, the replacement of sodium from a technological standpoint is possible, particularly by monovalent cations such as NH4(+), or K(+). However the levels of replacement need to take into account sensory attributes of the cationic salts.

  16. Reduced hepatic uptake and intestinal excretion of organic cations in mice with a targeted disruption of the organic cation transporter 1 (Oct1 [Slc22a1]) gene

    NARCIS (Netherlands)

    Jonker, JW; Wagenaar, E; Mol, CAAM; Buitelaar, M; Koepsell, H; Smit, JW; Schinkel, AH

    2001-01-01

    The polyspecific organic cation transporter 1 (OCT1 [SLC22A1]) mediates facilitated transport of small (hydrophilic) organic cations. OCT1 is localized at the basolateral membrane of epithelial cells in the liver, kidney, and intestine and could therefore be involved in the elimination of endogenous

  17. STXM / NEXAFS investigation of humic acid metal cation interaction

    Science.gov (United States)

    Plaschke, M.; Rothe, J.; Denecke, M. A.; Geckeis, H.

    2009-04-01

    Waste matrix dissolution following water intrusion in a future underground nuclear waste repository is regarded as a possible failure scenario leading to the dispersal of radioactive substances in the environment. Dissolved actinides, carriers of the long term radiotoxicity, may interact with groundwater constituents or sediment and host rock phases. These processes can either enhance or retard actinide mobility in the aquifer surrounding the repository. Actinide species may be highly mobile occuring as ‘eigen-colloids' or actinides adsorbed on groundwater colloids. The latter include dissolved humic acids (HA), mineral particles like iron oxides/hydroxides or clays and mineral/organic associations. The chemical characterization of these carrier colloids and a molecular scale understanding of the actinide-colloid interaction is a prerequisite to reliable prediction of actinide mobility based on model calculations. Therefore, chemical speciation information along with micro-scale morphology information is mandatory. Scanning Transmission X-ray Microscopy (STXM) is a powerful technique to reveal the chemical functionality and morphology of organic matter on a sub-µm scale. Moreover, STXM benefits from the ability to characterize organic samples in a thin film of aqueous solution. Morphological and microchemical information can be obtained at the same time within the spectral ‘water window' (i.e., between the C 1s and O 1s absorption edges at 284 eV and 537 eV, respectively). This ensures that complex hydrated structures of HA are kept in their native state. STXM investigations of HA in contact with polyvalent metal cations are carried out at the NSLS and SLS endstations. STXM micrographs at the carbon K-edge of metal cation loaded HA show optically dense zones (densification of carbon) embedded in a matrix of less dense material. Carboxyl groups are proposed to act as the primary HA cation attachment sites. NEXAFS (Near Edge Absorption Fine Structure) spectra of

  18. Increased cation conductance in human erythrocytes artificially aged by glycation.

    Science.gov (United States)

    Kucherenko, Yuliya V; Bhavsar, Shefalee K; Grischenko, Valentin I; Fischer, Uwe R; Huber, Stephan M; Lang, Florian

    2010-06-01

    Excessive glucose concentrations foster glycation and thus premature aging of erythrocytes. The present study explored whether glycation-induced erythrocyte aging is paralleled by features of suicidal erythrocyte death or eryptosis, which is characterized by cell membrane scrambling with subsequent phosphatidylserine exposure at the cell surface and cell shrinkage. Both are triggered by increases of cytosolic Ca(2+) concentration ([Ca(2+)](i)), which may result from activation of Ca(2+) permeable cation channels. Glycation was accomplished by exposure to high glucose concentrations (40 and 100 mM), phosphatidylserine exposure estimated from annexin binding, cell shrinkage from decrease of forward scatter, and [Ca(2+)](i) from Fluo3-fluorescence in analysis via fluorescence-activated cell sorter. Cation channel activity was determined by means of whole-cell patch clamp. Glycation of total membrane proteins, immunoprecipitated TRPC3/6/7, and immunoprecipitated L-type Ca(2+) channel proteins was estimated by Western blot testing with polyclonal antibodies used against advanced glycation end products. A 30-48-h exposure of the cells to 40 or 100 mM glucose in Ringer solution (at 37 degrees C) significantly increased glycation of membrane proteins, hemoglobin (HbA(1c)), TRPC3/6/7, and L-type Ca(2+) channel proteins, enhanced amiloride-sensitive, voltage-independent cation conductance, [Ca(2+)](i), and phosphatidylserine exposure, and led to significant cell shrinkage. Ca(2+) removal and addition of Ca(2+) chelator EGTA prevented the glycation-induced phosphatidylserine exposure and cell shrinkage after glycation. Glycation-induced erythrocyte aging leads to eryptosis, an effect requiring Ca(2+) entry from extracellular space.

  19. Monomer and dimer radical cations of benzene, toluene, and naphthalene.

    Science.gov (United States)

    Das, Tomi Nath

    2009-06-11

    Pulse radiolytic generation of monomeric and dimeric cations of benzene, toluene, and naphthalene in aqueous acid media at room temperature and their spectrophotometric characterization is discussed. Results presented include measurements of each aromatic's solubility in H(2)O-H(2)SO(4) and H(2)O-HClO(4) media over the acidity range pH 1 to H(0) -7.0, facile oxidative generation, and real-time identification of appropriate cationic transients with respective lambda(max) (nm) and epsilon (M(-1) cm(-1)) values measured as follows: C(6)H(6)(*+) (443, 1145 +/- 75), C(6)H(5)CH(3)(*+) (428, 1230 +/- 90), C(10)H(8)(*+) (381, 3650 +/- 225, and 687, 2210 +/- 160), (C(6)H(6))(2)(*+) (860, 2835 +/- 235), (C(6)H(5)CH(3))(2)(*+) (950, 1685 +/- 155), and (C(10)H(8))(2)(*+) (1040, 4170 +/- 320). Kinetic measurements reveal the respective formation rates of monomeric cations to be near-diffusion controlled, while the forward rate values for the dimeric species generation are marginally slower. The proton activity corrected pK(a) values are found to remain between -2.6 and -1.3 for the ArH(*+) species (C(6)H(6)(*+) most acidic, C(10)H(8)(*+) least acidic), while the pK(a) values of (ArH)(2)(*+) species vary from -5.0 to -3.0 ((C(6)H(6))(2)(*+) most acidic, (C(10)H(8))(2)(*+) least acidic). In H(0) -5 in aqueous H(2)SO(4), the respective stabilization energy of (C(6)H(6))(2)(*+), (C(6)H(5)CH(3))(2)(*+), and (C(10)H(8))(2)(*+) is estimated to be 16.6, 15.0, and 13.7 kcal mol(-1). Thus, the aqueous acid solution emerges as an alternative medium for typical radical-cationic studies, while offering compatibility for the deprotonated radical characterization near neutral pH.

  20. Protic Cationic Oligomeric Ionic Liquids of the Urethane Type

    DEFF Research Database (Denmark)

    Shevchenko, V. V.; Stryutsky, A. V.; Klymenko, N. S.;

    2014-01-01

    Protic oligomeric cationic ionic liquids of the oligo(ether urethane) type are synthesized via the reaction of an isocyanate prepolymer based on oligo(oxy ethylene)glycol with M = 1000 with hexamethylene-diisocyanate followed by blocking of the terminal isocyanate groups with the use of amine...... derivatives of imidazole, pyridine, and 3-methylpyridine and neutralization of heterocycles with ethanesulfonic acid and p-toluenesulfonic acid. The structures and properties of the synthesized oligomeric ionic liquids substantially depend on the structures of the ionic groups. They are amorphous at room...

  1. Synthesis of Branch Fluorinated Cationic Surfactant and Surface Properties

    Directory of Open Access Journals (Sweden)

    Hongke Wu

    2014-01-01

    Full Text Available A novel fluorinated quaternary ammonium salt cationic surfactant N,N,N-trimethyl-2-[[4-[[3,4,4,4-tetrafluoro-2-[1,2,2,2-tetrafluoro-1-(trifluoromethylethyl]-1,3-bis(tri-fluoromethyl-1-buten-1-yl]oxy]-benzoyl]amino]-iodide (FQAS was synthesized successfully, and its structure was characterized by FTIR, 1H-NMR, 19F-NMR, and MS. The surface activities of FQAS and the effect of temperature, electrolyte, and combination with hydrocarbon surfactant were investigated. The results showed that FQAS exhibited excellent surface activity and combination with hydrocarbon surfactant.

  2. Synthesis, Characterization, and Flocculation Properties of Branched Cationic Polyacrylamide

    Directory of Open Access Journals (Sweden)

    Weimin Sun

    2013-01-01

    Full Text Available A water soluble branched cationic polyacrylamide (BCPAM was synthesized using solution polymerization. The polymerization was initiated using potassium diperiodatocuprate, K5[Cu(HIO62](Cu(III, initiating the self-condensing vinyl copolymerization of acrylamide and acryloxyethyltrimethyl ammonium chloride (DAC monomer. The resulting copolymer was characterized by the use of Fourier-transform infrared (FTIR spectroscopy and nuclear magnetic resonance (NMR spectroscopy. Its flocculation properties were evaluated with standard jar tests of sewage. The effects of initiator concentration, monomer concentration, reaction temperature, and the mass ratio of monomers on intrinsic viscosity and flocculation properties of the product were determined using single-factor experiments and orthogonal experiment.

  3. Peak metamorphic temperatures from cation diffusion zoning in garnet

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Scherer, Erik; Mezger, Klaus

    2013-01-01

    A model that relates the characteristic diffusion length and average cooling rate to peak temperature was developed for chemical diffusion in spherical geometries on the basis of geospeedometry principles and diffusion theory. The model is quantitatively evaluated for cation diffusion profiles in...... is robust and provides a reliable means of estimating peak temperatures for different types of high-grade metamorphic rock. The tool could be of particular advantage in rocks where critical assemblages for conventional thermometry do not occur or have been replaced during retrogression....

  4. A NEW METHOD TO SYNTHESIZE THE CATIONIC GRAFT STARCH

    Institute of Scientific and Technical Information of China (English)

    Lin Li; Bingyue Liu; Yafeng Cao

    2004-01-01

    The cationic graft copolymer was synthesized by reversed phase emulsion copolymerization of starch with diallydimethyl ammoniumlchlorid (DADMAC)and acrylamide (AM). The copolymerization was carried out using (NH4)2S2O8-NH2CONH2 redox as initiator and selecting Span-20 as emulsifier. The effects of emulsifier content in oil phase, volume ratio of oil to water, initiator concentration and mole ratio of DADMAC to AM on the graft copolymerization were discussed. The optimum condition of synthetics was found with the orthogonal test method.

  5. Blackbody-induced radiative dissociation of cationic SF 6 clusters

    DEFF Research Database (Denmark)

    Toker, Jonathan; Rahinov, I.; Schwalm, D.;

    2012-01-01

    The stability of cationic SF5+(SF6)n−1 clusters was investigated by measuring their blackbody-induced radiative dissociation (BIRD) rates. The clusters were produced in a supersonic expansion ion source and stored in an electrostatic ion-beam trap at room temperature, where their abundances...... and lifetimes were measured. Using the “master equation” approach, relative binding energies of an SF6 unit in the clusters could be extracted from the storage-time dependence of the survival probabilities. The results allow for a deeper insight into the effect of a localized charge on the structure...... and stability of SF6-based clusters....

  6. Holographic Grating Formation in Cationic Photopolymers with Dark Reaction

    Institute of Scientific and Technical Information of China (English)

    WEI Hao-Yun; CAO Liang-Cai; GU Claire; XU Zhen-Feng; HE Ming-Zhao; HE Qing-Sheng; HE Shu-Rong; JIN Guo-Fan

    2006-01-01

    @@ We propose a new formula to describe the dynamics of holographic grating formation under low intensity pulse exposures in cationic photopolymers, in which the dark reaction contributes dominantly to the grating strength.The formula is based on the living polymerization mechanism and the diffusion-free approximation. The analytical solution indicates that the grating formation time depends on the termination rate constant, while the final grating strength depends linearly on the total exposure energy. These theoretical predictions are verified experimentally using the Aprilis HMC-400μm photopolymer. The results can provide guidelines for the control and optimization of the holographic recording conditions in practical applications.

  7. Properties of sulfonated cation-exchangers made from petroleum asphaltites

    Energy Technology Data Exchange (ETDEWEB)

    Pokonova, Yu.V.; Pol' kin, G.B.; Proskuryakov, V.A.

    1982-01-10

    The use of ion-exchangers in radiochemical technology is accompanied by changes of their properties under the influence of ionizing radiation. The rate of development of these processes depends on the nature and structure of the matrix and on the nature and amount of ionic groups. We have proposed a method of synthesis of ion-exchangers resistant to ..gamma.. radiation from petroleum asphaltites. Continuing these investigations, we prepared cation-exchangers by sulfonation of a mixture of petroleum asphaltites and acid asphalt. An investigation of their radiation resistance is described in this paper.

  8. Incorporation of Monovalent Cations in Sulfate Green Rust

    DEFF Research Database (Denmark)

    Christiansen, B. C.; Dideriksen, K.; Katz, A.;

    2014-01-01

    Green rust is a naturally occurring layered mixed-valent ferrous-ferric hydroxide, which can react with a range of redox-active compounds. Sulfate-bearing green rust is generally thought to have interlayers composed of sulfate and water. Here, we provide evidence that the interlayers also contain...... with water showed that Na+ and K+ were structurally fixed in the interlayer, whereas Rb+ and Cs+ could be removed, resulting in a decrease in the basal layer spacing. The incorporation of cations in the interlayer opens up new possibilities for the use of sulfate green rust for exchange reactions with both...

  9. EXAFS determination of cation local order in layered perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Montero C, M. E.; Fuentes M, L.; Duarte M, J. A.; Fuentes C, L. [Centro de Investigacion en Materiales Avanzados S. C., Miguel de Cervantes Saavedra 120, Complejo Industrial Chihuahua, 31109 Chihuahua (Mexico); Garcia G, M. [Instituto de Fisica, UNAM, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Mehta, A.; Webb, S. [Stanford Synchrotron Radiation Laboratory, CA (United States)

    2008-02-15

    EXAFS analysis of Bi{sub 6}Ti{sub 3}Fe{sub 2}O{sub 18} Aurivillius ceramic was performed to elucidate the local environment of Fe cations. Experiments were performed at Stanford Synchrotron Radiation Laboratory, at T = 10, 30, 50, 75, 100 and 298 K, in fluorescence regime. EXAFS spectra were processed using the ab initio multiple scattering program FEFF6. Distances among representative atomic pairs were refined. As a basic result, the previous hypothesis suggested by X-ray diffraction experiments, regarding a preference of iron atoms for the centered perovskite layer of the unit cell, was confirmed. (Author)

  10. Spontaneous Superlattice Formation in Nanorods through PartialCation Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Richard D.; Sadtler, Bryce; Demchenko, Denis O.; Erdonmez, Can K.; Wang, Lin-Wang; Alivisatos, A. Paul

    2007-03-14

    Lattice mismatch strains are widely known to controlnanoscale pattern formation in heteroepitaxy, but such effects have notbeen exploited in colloidal nanocrystal growth. We demonstrate acolloidal route to synthesizing CdS-Ag2S nanorod superlattices throughpartial cation exchange. Strain induces the spontaneous formation ofperiodic structures. Ab initio calculations of the interfacial energy andmodeling of strain energies show that these forces drive theself-organization. The nanorod superlattices exhibit high stabilityagainst ripening and phase mixing. These materials are tunablenear-infrared emitters with potential applications as nanometer-scaleoptoelectronic devices.

  11. Cationic polyacrylamides enhance rates of starch and cellulose saccharification.

    Science.gov (United States)

    Reye, John T; Maxwell, Kendra; Rao, Swati; Lu, Jian; Banerjee, Sujit

    2009-10-01

    Adding a cationic polyacrylamide (c-PAM) to either the amylase mediated hydrolysis of corn starch or the hydrolysis of wood fiber by cellulase can enhance the initial hydrolysis rates, although a rate decrease can occur under some conditions. Several c-PAMs can serve as catalysts and the same c-PAM can improve the efficiency of both amylase and cellulase. The initial amylase rate approximately doubles; the analogous cellulase hydrolysis rate increases by about 40%. c-PAMs increase the binding of enzyme to substrate.

  12. Ensemble classi…cation methods for autism disordered speech

    Directory of Open Access Journals (Sweden)

    Zoubir Abdeslem Benselama

    2016-09-01

    Full Text Available In this paper, we present the results of our investigation on Autism classifi…cation by applying ensemble classi…ers to disordered speech signals. The aim is to distinguish between Autism sub-classes by comparing an ensemble combining three decision methods, the sequential minimization optimization (SMO algorithm, the random forests (RF, and the feature-subspace aggregating approach (Feating. The conducted experiments allowed a reduction of 30% of the feature space with an accuracy increase over the baseline of 8.66% in the development set and 6.62% in the test set.

  13. Contributions of cation-π interactions to the collagen triple helix stability.

    Science.gov (United States)

    Chen, Chia-Ching; Hsu, Wei; Hwang, Kuo-Chu; Hwu, Jih Ru; Lin, Chun-Cheng; Horng, Jia-Cherng

    2011-04-01

    Cation-π interactions are found to be an important noncovalent force in proteins. Collagen is a right-handed triple helix composed of three left-handed PPII helices, in which (X-Y-Gly) repeats dominate in the sequence. Molecular modeling indicates that cation-π interactions could be formed between the X and Y positions in adjacent collagen strands. Here, we used a host-guest peptide system: (Pro-Hyp-Gly)(3)-(Pro-Y-Gly-X-Hyp-Gly)-(Pro-Hyp-Gly)(3), where X is an aromatic residue and Y is a cationic residue, to study the cation-π interaction in the collagen triple helix. Circular dichroism (CD) measurements and Tm data analysis show that the cation-π interactions involving Arg have a larger contribution to the conformational stability than do those involving Lys, and Trp forms a weaker cation-π interaction with cationic residues than expected as a result of steric effects. The results also show that the formation of cation-π interactions between Arg and Phe depends on their relative positions in the strand. Moreover, the fluorinated and methylated Phe substitutions show that an electron-withdrawing or electron-donating substituent on the aromatic ring can modulate its π-electron density and the cation-π interaction in collagen. Our data demonstrate that the cation-π interaction could play an important role in stabilizing the collagen triple helix.

  14. Hydrogen release reactions of Al-based complex hydrides enhanced by vibrational dynamics and valences of metal cations.

    Science.gov (United States)

    Sato, T; Ramirez-Cuesta, A J; Daemen, L; Cheng, Y-Q; Tomiyasu, K; Takagi, S; Orimo, S

    2016-09-27

    Hydrogen release from Al-based complex hydrides composed of metal cation(s) and [AlH4](-) was investigated using inelastic neutron scattering viewed from vibrational dynamics. The hydrogen release followed the softening of translational and [AlH4](-) librational modes, which was enhanced by vibrational dynamics and the valence(s) of the metal cation(s).

  15. Cation Guided Assembly: Crystal Structures of Two Ag(I) Complexes in Versatile Dimensionalities with Different Counter Cations

    Institute of Scientific and Technical Information of China (English)

    WANG, Jiang-Yun; GU, Wen; WANG, Wen-Zhen; LIU, Xin; LIAO, Dai-Zheng

    2006-01-01

    Assembly of [Ag(CN)2]- units with M(Ⅱ)-diamine complex cations [Cu(LN-N)2]2+, where LN-N represents1,2-diaminopropane (pn) and ethylenediamine (en), afforded two complexes, [Cu(pn)2][Ag2(CN)4] (1) and[Cu(en)2][Ag3(CN)5] (2), which were characterized by elemental analysis, IR, UV-Vis and ESR spectra. Single crystal X-ray analyses show that these complexes have 2D and 3D architectures through silver-silver interactions and other weak interactions. The luminescence behaviors of the two complexes were also studied by means of emission spectra.

  16. Molecular Dynamics Study of a Dual-Cation Ionomer Electrolyte.

    Science.gov (United States)

    Chen, Xingyu; Chen, Fangfang; Jónsson, Erlendur; Forsyth, Maria

    2017-01-18

    The poly(N1222 )x Li1-x [AMPS] ionomer system (AMPS=2-acrylamido-2-methylpropane sulfonic acid) with dual cations has previously shown decoupled Li ion dynamics from polymer segmental motions, characterized by the glass-transition temperature, which can result in a conductive electrolyte material whilst retaining an appropriate modulus (i.e. stiffness) so that it can suppress dendrite formation, thereby improving safety when used in lithium-metal batteries. To understand this ion dynamics behavior, molecular dynamics techniques have been used in this work to simulate structure and dynamics in these materials. These simulations confirm that the Li ion transport is decoupled from the polymer particularly at intermediate N1222(+) concentrations. At 50 mol % N1222(+) concentration, the polymer backbone is more rigid than for higher N1222(+) concentrations, but with increasing temperature Li ion dynamics are more significant than polymer or quaternary ammonium cation motions. Herein we suggest an ion-hopping mechanism for Li(+) , arising from structural rearrangement of ionic clusters that could explain its decoupled behavior. Higher temperatures favor an aggregated ionic structure as well as enhancing these hopping motions. The simulations discussed here provide an atomic-level understanding of ion dynamics that could contribute to designing an improved ionomer with fast ion transport and mechanical robustness.

  17. USING COLLOIDAL LAYERED DOUBLE HYDROXIDES AS CATIONIC MICROPARTICULATE COMPONENT

    Institute of Scientific and Technical Information of China (English)

    Songlin Wang; Wenxia Liu

    2004-01-01

    Layered double hydroxides consisting of layers with cationic charges may be potential candidates of cationic microparticles forming synergetic retention effect with anionic polyacrylamide. In this work, the layered double hydroxides with various molar ratios of Mg/Al were synthesized by co-precipitation of magnesium chloride and aluminum chloride and peptized by intense washing with water. The chemical formula, particle size, Zeta potential of the layered double hydroxide were analyzed. It was found that positively charged magnesium aluminum hydroxide with particle diameter in nanoparticle size could be prepared. The Zeta potential and particle size vary with the feed molar ratio of Mg/Al and the peptizing process, respectively. The Zeta potential is also pH dependent. The retention experiments carried out on DDJ show that when used together with anionic polyacrylamide, the positively charged colloidal double hydroxide greatly improves the retention of reed pulps. The chemical formula, particle size and Zeta potential of the colloidal double hydroxide all affect its retention behavior.

  18. The cation content of phospholipides from swine erythrocytes.

    Science.gov (United States)

    KIRSCHNER, L B

    1958-11-20

    Phospholipides from swine erythrocytes were isolated and separated into four reproducible fractions. One of the fractions seems to be pure phosphatidylserine. The others are almost certainly not single compounds, although the analytical data indicate that they represent mixtures considerably simpler than the parent mixture extracted from the cells. All four fractions contained Na(+) and K(+), but very little Ca(2+). Sodium was the predominant cation in two of the fractions under all conditions although the major intracellular cation was potassium. In the other two fractions the ratio Na/K varied with the extraction procedure largely because the quantity of K(+) seemed to depend on the solvent system used. There appear to be reasons to believe that the entire system of phospholipides binds Na(+) preferentially. In addition, it was observed that the quantity of Na(+) found in the lipide extracts varied when the extrusion of Na(+) from the cells was made to vary. Both of these observations are consistent with the possibility that the phospholipides play some part in the extrusion of Na(+) from these cells.

  19. Effects of cation concentration on photocatalytic performance over magnesium vanadates

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peng [Catalytic Materials Group, Environmental Remediation Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Zhou, Wei [Department of Physics, Tianjin University, 92 Weijin Road, Nankai District, Tianjin (China); Wang, Xin; Zhang, Yan; Wang, Defa [TU-NIMS Joint Research Center, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin (China); Umezawa, Naoto, E-mail: UMEZAWA.Naoto@nims.go.jp, E-mail: ABE.Hideki@nims.go.jp; Abe, Hideki, E-mail: UMEZAWA.Naoto@nims.go.jp, E-mail: ABE.Hideki@nims.go.jp [Catalytic Materials Group, Environmental Remediation Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); TU-NIMS Joint Research Center, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin (China); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ye, Jinhua [Catalytic Materials Group, Environmental Remediation Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); TU-NIMS Joint Research Center, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin (China); International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2015-10-01

    A series of magnesium vanadates (MgV {sub 2}O{sub 6}, Mg{sub 2}V {sub 2}O{sub 7}, and Mg{sub 3}V {sub 2}O{sub 8}) were synthesized to investigate the effect of cation concentration on photocatalytic performance. The samples were characterized by X-ray diffraction, field emission-scanning electron microscopy, UV-visible diffuse reflectance spectroscopy, and fluorescence spectroscopy. The photocatalytic O{sub 2} evolution experiments under visible light irradiation showed Mg{sub 2}V {sub 2}O{sub 7} exhibits the best performance, while Mg{sub 3}V {sub 2}O{sub 8} has the lowest activity. The density functional theory calculations indicated that the lowest unoccupied states of Mg{sub 3}V {sub 2}O{sub 8} are the mostly localized by the cation layers. The fluorescence spectra and fluorescence decay curves gave evident performances of excited states of magnesium vanadates and pointed out MgV {sub 2}O{sub 6} has a very short excited electron lift-time. Mg{sub 2}V {sub 2}O{sub 7} performs high photocatalytic activity because of its high electron mobility and long electron life-time.

  20. H2O Nucleation Around Noble Metal Cations

    Science.gov (United States)

    Calaminici, Patrizia; Oropeza Alfaro, Pavel; Juarez Flores, Martin; Köster, Andreas; Beltran, Marcela; Ulises Reveles, J.; Khanna, Shiv N.

    2008-03-01

    First principle electronic structure calculations have been carried out to investigate the ground state geometry, electronic structure and binding energy of noble metal cations (H2O)n^+ clusters containing up to 10 H2O molecules. The calculations are performed with the density functional theory code deMon2k [1]. Due to the very flat potential energy surface of these systems special care to the numerical stability of energy and gradient calculation must be taken.Comparison of the results obtained with Cu^+, Ag^+ and Au^+ will be shown. This investigation provides insight into the structural arrangement of the water molecules around these metals and a microscopic understanding of the observed incremental binding energy in the case of the gold cation based on collision induced dissociation experiments. [1] A.M. Köster, P. Calaminici, M.E. Casida, R. Flores-Moreno, G. Geudtner, A. Goursot, T. Heine, A. Ipatov, F. Janetzko, J. Martin del Campo, S. Patchkovski, J.U. Reveles, A. Vela and D.R. Salahub, deMon2k, The deMon Developers, Cinvestav, 2006

  1. Cationic gadolinium chelate for magnetic resonance imaging of cartilaginous defects.

    Science.gov (United States)

    Nwe, Kido; Huang, Ching-Hui; Qu, Feini; Warden-Rothman, Robert; Zhang, Clare Y; Mauck, Robert L; Tsourkas, Andrew

    2016-05-01

    The ability to detect meniscus defects by magnetic resonance arthrography (MRA) can be highly variable. To improve the delineation of fine tears, we synthesized a cationic gadolinium complex, (Gd-DOTA-AM4 )(2+) , that can electrostatically interact with Glycosaminoglycans (GAGs). The complex has a longitudinal relaxivity (r1) of 4.2 mM(-1) s(-1) and is highly stable in serum. Its efficacy in highlighting soft tissue tears was evaluated in comparison to a clinically employed contrast agent (Magnevist) using explants obtained from adult bovine menisci. In all cases, Gd-DOTA-AM4 appeared to improve the ability to detect the soft tissue defect by providing increased signal intensity along the length of the tear. Magnevist shows a strong signal near the liquid-meniscus interface, but much less contrast is observed within the defect at greater depths. This provides initial evidence that cationic contrast agents can be used to improve the diagnostic accuracy of MRA. Copyright © 2016 John Wiley & Sons, Ltd.

  2. Role of Reverse Divalent Cation Diffusion in Forward Osmosis Biofouling.

    Science.gov (United States)

    Xie, Ming; Bar-Zeev, Edo; Hashmi, Sara M; Nghiem, Long D; Elimelech, Menachem

    2015-11-17

    We investigated the role of reverse divalent cation diffusion in forward osmosis (FO) biofouling. FO biofouling by Pseudomonas aeruginosa was simulated using pristine and chlorine-treated thin-film composite polyamide membranes with either MgCl2 or CaCl2 draw solution. We related FO biofouling behavior-water flux decline, biofilm architecture, and biofilm composition-to reverse cation diffusion. Experimental results demonstrated that reverse calcium diffusion led to significantly more severe water flux decline in comparison with reverse magnesium permeation. Unlike magnesium, reverse calcium permeation dramatically altered the biofilm architecture and composition, where extracellular polymeric substances (EPS) formed a thicker, denser, and more stable biofilm. We propose that FO biofouling was enhanced by complexation of calcium ions to bacterial EPS. This hypothesis was confirmed by dynamic and static light scattering measurements using extracted bacterial EPS with the addition of either MgCl2 or CaCl2 solution. We observed a dramatic increase in the hydrodynamic radius of bacterial EPS with the addition of CaCl2, but no change was observed after addition of MgCl2. Static light scattering revealed that the radius of gyration of bacterial EPS with addition of CaCl2 was 20 times larger than that with the addition of MgCl2. These observations were further confirmed by transmission electron microscopy imaging, where bacterial EPS in the presence of calcium ions was globular, while that with magnesium ions was rod-shaped.

  3. Effect of cationic monomer on properties of fluorinated acrylate latex

    Institute of Scientific and Technical Information of China (English)

    Li Jun Chen

    2012-01-01

    Cationic fluorinated acrylate latex was prepared via semi-continuous emulsion copolymerization of cationic monomer and other monomers.The resultant latex and its film were characterized with dynamic light scattering detector and contact angle meter.Influences of amount of DMDAAC on the properties of resultant latex and its film were investigated in detail.Results show that the particle size of the latex has the minimum value and the zeta potential of the latex is increased when the amount of DMDAAC is increased.In addition,the particle size of the latex is unimodal distribution when the amount of DMDAAC is not more than 2.5%.However,the particle size of the latex is bimodal distribution when the amount of DMDAAC is more than 2.5%.The contact angle is varied slightly with the increase of amount of DMDAAC when it is not more than 2.5%.Nevertheless,the contact angle is decreased with the increase of the amount of DMDAAC when it is more than 25%.

  4. Stretch-activated cation channel from larval bullfrog skin

    DEFF Research Database (Denmark)

    Hillyard, Stanley D; Willumsen, Niels J; Marrero, Mario B

    2010-01-01

    Cell-attached patches from isolated epithelial cells from larval bullfrog skin revealed a cation channel that was activated by applying suction (-1 kPa to -4.5 kPa) to the pipette. Activation was characterized by an initial large current spike that rapidly attenuated to a stable value and showed...... was markedly reduced with N-methyl-D-glucamide (NMDG)-Cl Ringer's solution in the pipette. Neither amiloride nor ATP, which are known to stimulate an apical cation channel in Ussing chamber preparations of larval frog skin, produced channel activation nor did these compounds affect the response to suction....... Stretch activation was not affected by varying the pipette concentrations of Ca(2+) between 0 mmol l(-1) and 4 mmol l(-1) or by varying pH between 6.8 and 8.0. However, conductance was reduced with 4 mmol l(-1) Ca(2+). Western blot analysis of membrane homogenates from larval bullfrog and larval toad skin...

  5. Structural Insights into Mitochondrial Calcium Uniporter Regulation by Divalent Cations.

    Science.gov (United States)

    Lee, Samuel K; Shanmughapriya, Santhanam; Mok, Mac C Y; Dong, Zhiwei; Tomar, Dhanendra; Carvalho, Edmund; Rajan, Sudarsan; Junop, Murray S; Madesh, Muniswamy; Stathopulos, Peter B

    2016-09-22

    Calcium (Ca(2+)) flux into the matrix is tightly controlled by the mitochondrial Ca(2+) uniporter (MCU) due to vital roles in cell death and bioenergetics. However, the precise atomic mechanisms of MCU regulation remain unclear. Here, we solved the crystal structure of the N-terminal matrix domain of human MCU, revealing a β-grasp-like fold with a cluster of negatively charged residues that interacts with divalent cations. Binding of Ca(2+) or Mg(2+) destabilizes and shifts the self-association equilibrium of the domain toward monomer. Mutational disruption of the acidic face weakens oligomerization of the isolated matrix domain and full-length human protein similar to cation binding and markedly decreases MCU activity. Moreover, mitochondrial Mg(2+) loading or blockade of mitochondrial Ca(2+) extrusion suppresses MCU Ca(2+)-uptake rates. Collectively, our data reveal that the β-grasp-like matrix region harbors an MCU-regulating acidic patch that inhibits human MCU activity in response to Mg(2+) and Ca(2+) binding.

  6. Excited state dynamics of the astaxanthin radical cation

    Science.gov (United States)

    Amarie, Sergiu; Förster, Ute; Gildenhoff, Nina; Dreuw, Andreas; Wachtveitl, Josef

    2010-07-01

    Femtosecond transient absorption spectroscopy in the visible and NIR and ultrafast fluorescence spectroscopy were used to examine the excited state dynamics of astaxanthin and its radical cation. For neutral astaxanthin, two kinetic components corresponding to time constants of 130 fs (decay of the S 2 excited state) and 5.2 ps (nonradiative decay of the S 1 excited state) were sufficient to describe the data. The dynamics of the radical cation proved to be more complex. The main absorption band was shifted to 880 nm (D 0 → D 3 transition), showing a weak additional band at 1320 nm (D 0 → D 1 transition). We found, that D 3 decays to the lower-lying D 2 within 100 fs, followed by a decay to D 1 with a time constant of 0.9 ps. The D 1 state itself exhibited a dual behavior, the majority of the population is transferred to the ground state in 4.9 ps, while a small population decays on a longer timescale of 40 ps. Both transitions from D 1 were found to be fluorescent.

  7. High and rapid alkali cation storage in ultramicroporous carbonaceous materials

    Science.gov (United States)

    Yun, Young Soo; Lee, Seulbee; Kim, Na Rae; Kang, Minjee; Leal, Cecilia; Park, Kyu-Young; Kang, Kisuk; Jin, Hyoung-Joon

    2016-05-01

    To achieve better supercapacitor performance, efforts have focused on increasing the specific surface area of electrode materials to obtain higher energy and power density. The control of pores in these materials is one of the most effective ways to increase the surface area. However, when the size of pores decreases to a sub-nanometer regime, it becomes difficult to apply the conventional parallel-plate capacitor model because the charge separation distance (d-value) of the electrical double layer has a similar length scale. In this study, ultramicroporous carbonaceous materials (UCMs) containing sub-nanometer-scale pores are fabricated using a simple in situ carbonization/activation of cellulose-based compounds containing potassium. The results show that alkali cations act as charge carriers in the ultramicropores (<0.7 nm), and these materials can deliver high capacitances of ∼300 F g-1 at 0.5 A g-1 and 130 F g-1, even at a high current rate of 65 A g-1 in an aqueous medium. In addition, the UCM-based symmetric supercapacitors are stable over 10,000 cycles and have a high energy and power densities of 8.4 Wh kg-1 and 15,000 W kg-1, respectively. This study provides a better understanding of the effects of ultramicropores in alkali cation storage.

  8. Cationic Nanocylinders Promote Angiogenic Activities of Endothelial Cells

    Directory of Open Access Journals (Sweden)

    Jung Bok Lee

    2016-01-01

    Full Text Available Polymers have been used extensively taking forms as scaffolds, patterned surface and nanoparticle for regenerative medicine applications. Angiogenesis is an essential process for successful tissue regeneration, and endothelial cell–cell interaction plays a pivotal role in regulating their tight junction formation, a hallmark of angiogenesis. Though continuous progress has been made, strategies to promote angiogenesis still rely on small molecule delivery or nuanced scaffold fabrication. As such, the recent paradigm shift from top-down to bottom-up approaches in tissue engineering necessitates development of polymer-based modular engineering tools to control angiogenesis. Here, we developed cationic nanocylinders (NCs as inducers of cell–cell interaction and investigated their effect on angiogenic activities of human umbilical vein endothelial cells (HUVECs in vitro. Electrospun poly (l-lactic acid (PLLA fibers were aminolyzed to generate positively charged NCs. The aninolyzation time was changed to produce two different aspect ratios of NCs. When HUVECs were treated with NCs, the electrostatic interaction of cationic NCs with negatively charged plasma membranes promoted migration, permeability and tubulogenesis of HUVECs compared to no treatment. This effect was more profound when the higher aspect ratio NC was used. The results indicate these NCs can be used as a new tool for the bottom-up approach to promote angiogenesis.

  9. Source of Lake Vostok Cations Constrained with Strontium Isotopes

    Science.gov (United States)

    Lyons, William; Welch, Kathleen; Priscu, John; Tranter, Martyn; Royston-Bishop, George

    2016-08-01

    Lake Vostok is the largest sub-glacial lake in Antarctica. The primary source of our current knowledge regarding the geochemistry and biology of the lake comes from the analysis of refrozen lake water associated with ice core drilling. Several sources of dissolved ions and particulate matter to the lake have been proposed, including materials from the melted glacier ice, the weathering of underlying geological materials, hydrothermal activity and underlying, ancient evaporitic deposits. A sample of Lake Vostok Type 1 accretion ice has been analyzed for its 87Sr/86Sr signature as well as its major cation and anion and Sr concentrations. The strontium isotope ratio of 0.71655 and the Ca/Sr ratio in the sample strongly indicate that the major source of the Sr is from aluminosilicate minerals from the continental crust. These data imply that at least a portion of the other cations in the Type 1 ice also are derived from continental crustal materials and not hydrothermal activity, the melted glacier ice, or evaporitic sources.

  10. Synthesis and rheological properties of cation-exchanged Laponite suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Phuoc, Tran X. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Univ. of Pittsburgh, PA (United States); Howard, Bret H. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Chyu, Minking K. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Univ. of Pittsburgh, PA (United States)

    2009-11-01

    In this paper we report our new approach to synthesize cation-exchanged Laponite suspensions. General observations of the prepared samples indicated that an aqueous suspension of 1 wt.% Laponite retained its free flowing liquid phase characteristics even after aging for several weeks. When bivalent cationic metals (Cu, Co, Ni) were ablated into the suspension, the strong charge of the crystal face was reduced and, on standing, the suspension gelled becoming highly viscous. This sol-gel transition was induced by the formation of a space-filled structure due to both van der Waals and electrostatic bonds between the positively charged rims and negatively charged faces. Rheological properties of such prepared suspensions were measured using a Brookfield DV-II Pro Viscometer with a small sample adapter (SSA18/13RPY). The yield strengths of 2.2 N/m2, 3.2 N/m2, and 1.7 N/m2 were measured for Ni-, Co-, and Cumodified Laponite suspensions, respectively. These yield strengths are sufficiently high for suspending weighting materials such as barite which requires the gel strength of about 0.5 N/m2.

  11. Synthesis and rheological properties of cation exchanged Laponite suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Tran, X P; Howard, B; Chyu, M K

    2009-01-01

    In this paper we report our new approach to synthesize cation-exchanged Laponite suspensions. General observations of the prepared samples indicated that an aqueous suspension of 1 wt% Laponite retained its free flowing liquid phase characteristics even after aging for several weeks. When bivalent cationic metals (Cu, Co, Ni) were ablated into the suspension, the strong charge of the crystal face was reduced and, on standing, the suspension gelled becoming highly viscous. This sol-gel transition was induced by the formation of a space-filled structure due to both van derWaals and electrostatic bonds between the positively charged rims and negatively charged faces. Rheological properties of such prepared suspensions were measured using a Brookfield DV-H Pro Viscometer with a small sample adapter{SSA18/13RPY). The yield strengths of2.2 N/m2, 3.2 N/m2, and 1.7 N/m2 were measured for Ni-, Co-, and Cu-modified Laponite suspensions, respectively. These yield strengths are sufficiently high for suspending weighting materials such as barite which requires the gel strength of about 0.5 N/m2.

  12. Anionic and cationic Hofmeister effects on hydrophobic and hydrophilic surfaces.

    Science.gov (United States)

    Schwierz, Nadine; Horinek, Dominik; Netz, Roland R

    2013-02-26

    Using a two-step modeling approach, we address the full spectrum of direct, reversed, and altered ionic sequences as the charge of the ion, the charge of the surface, and the surface polarity are varied. From solvent-explicit molecular dynamics simulations, we extract single-ion surface interaction potentials for halide and alkali ions at hydrophilic and hydrophobic surfaces. These are used within Poisson-Boltzmann theory to calculate ion density and electrostatic potential distributions at mixed polar/unpolar surfaces for varying surface charge. The resulting interfacial tension increments agree quantitatively with experimental data and capture the Hofmeister series, especially the anomaly of lithium, which is difficult to obtain using continuum theory. Phase diagrams that feature different Hofmeister series as a function of surface charge, salt concentration, and surface polarity are constructed from the long-range force between two surfaces interacting across electrolyte solutions. Large anions such as iodide have a high hydrophobic surface affinity and increase the effective charge magnitude on negatively charged unpolar surfaces. Large cations such as cesium also have a large hydrophobic surface affinity and thereby compensate an external negative charge surface charge most efficiently, which explains the well-known asymmetry between cations and anions. On the hydrophilic surface, the size-dependence of the ion surface affinity is reversed, explaining the Hofmeister series reversal when comparing hydrophobic with hydrophilic surfaces.

  13. Cation charge dependence of the forces driving DNA assembly.

    Science.gov (United States)

    DeRouchey, Jason; Parsegian, V Adrian; Rau, Donald C

    2010-10-20

    Understanding the strength and specificity of interactions among biologically important macromolecules that control cellular functions requires quantitative knowledge of intermolecular forces. Controlled DNA condensation and assembly are particularly critical for biology, with separate repulsive and attractive intermolecular forces determining the extent of DNA compaction. How these forces depend on the charge of the condensing ion has not been determined, but such knowledge is fundamental for understanding the basis of DNA-DNA interactions. Here, we measure DNA force-distance curves for a homologous set of arginine peptides. All forces are well fit as the sum of two exponentials with 2.4- and 4.8-Å decay lengths. The shorter-decay-length force is always repulsive, with an amplitude that varies slightly with length or charge. The longer-decay-length force varies strongly with cation charge, changing from repulsion with Arg¹ to attraction with Arg². Force curves for a series of homologous polyamines and the heterogeneous protein protamine are quite similar, demonstrating the universality of these forces for DNA assembly. Repulsive amplitudes of the shorter-decay-length force are species-dependent but nearly independent of charge within each species. A striking observation was that the attractive force amplitudes for all samples collapse to a single curve, varying linearly with the inverse of the cation charge.

  14. The influence of large cations on the electrochemical properties of tunnel-structured metal oxides

    Science.gov (United States)

    Yuan, Yifei; Zhan, Chun; He, Kun; Chen, Hungru; Yao, Wentao; Sharifi-Asl, Soroosh; Song, Boao; Yang, Zhenzhen; Nie, Anmin; Luo, Xiangyi; Wang, Hao; Wood, Stephen M.; Amine, Khalil; Islam, M. Saiful; Lu, Jun; Shahbazian-Yassar, Reza

    2016-11-01

    Metal oxides with a tunnelled structure are attractive as charge storage materials for rechargeable batteries and supercapacitors, since the tunnels enable fast reversible insertion/extraction of charge carriers (for example, lithium ions). Common synthesis methods can introduce large cations such as potassium, barium and ammonium ions into the tunnels, but how these cations affect charge storage performance is not fully understood. Here, we report the role of tunnel cations in governing the electrochemical properties of electrode materials by focusing on potassium ions in α-MnO2. We show that the presence of cations inside 2 × 2 tunnels of manganese dioxide increases the electronic conductivity, and improves lithium ion diffusivity. In addition, transmission electron microscopy analysis indicates that the tunnels remain intact whether cations are present in the tunnels or not. Our systematic study shows that cation addition to α-MnO2 has a strong beneficial effect on the electrochemical performance of this material.

  15. Flexible polyelectrolyte conformation in the presence of cationic and anionic surfactants

    Science.gov (United States)

    Passos, C. B.; Kuhn, P. S.; Diehl, A.

    2015-11-01

    In this work we have studied the conformation of flexible polyelectrolyte chains in the presence of cationic and anionic surfactant molecules. We developed a simple theoretical model for the formation of the polyelectrolyte-cationic surfactant complexes and mixed micelles formed by cationic and anionic surfactant molecules, in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, with the hydrophobic interaction included explicitly as an effective short-ranged attraction between the surfactant hydrocarbon tails. This simple model allows us to calculate the extension of the polyelectrolyte-cationic surfactant complexes as a function of the anionic surfactant concentration, for different types of cationic and anionic surfactant molecules. A discrete conformational transition from a collapsed state to an elongated coil was found, for all surfactant chain lengths we have considered, in agreement with the experimental observations for the unfolding of ​DNA-cationic surfactant complexes.

  16. Resonance Raman and quantum chemical studies of short polyene radical cations

    DEFF Research Database (Denmark)

    Keszthelyi, T.; Wilbrandt, R.; Bally, T.

    1997-01-01

    The results of our investigations of the geometric and vibrational structures of some short conjugated polyene radical cations are reported. The radical cations of 1,3-butadiene and three of its deuterated isotopomers, trans- and cis-1,3-pentadiene, 2-methyl-1,3-butadiene, and E- and Z-1,3,5-hexa......The results of our investigations of the geometric and vibrational structures of some short conjugated polyene radical cations are reported. The radical cations of 1,3-butadiene and three of its deuterated isotopomers, trans- and cis-1,3-pentadiene, 2-methyl-1,3-butadiene, and E- and Z-1...... and to assist assignment of the resonance Raman spectra. A new and improved scaled quantum mechanical force field for the butadiene radical cation was also determined. The presence of more than one rotamer was observed in all the polyene radical cations we investigated. (C) 1997 Elsevier Science B.V....

  17. Improving reactive ink jet printing via cationization of cellulosic linen fabric.

    Science.gov (United States)

    Rekaby, M; Abd-El Thalouth, J I; Abd El-Salam, Sh H

    2013-11-06

    Cellulose linen fabric samples subjected to cationization using different cationizing agents: dodecyl trimethyl ammonium bromide (DTAB), tetra methyl ammonium hydroxide (TMAH), and Quat-188, via pad batch technique, followed by ink jet printing with reactive dyes. The %N as well as the K/S of the cationized samples was found to be depends on: (a) the nature of the cationizing agent and (b) on the time of batching. As the latter increases both of the nitrogen content and K/S increases to a maximum depending on the nature of the reagent used. Further increase in the batching time up to 30 h is accompanied by a decrease in both the %N and K/S irrespective of the nature of the cationizing agent used. Cationization improves the printability of reactive dye ink jet printed linen fabrics with no remarkable effect on the overall color fastness properties.

  18. Cation-{pi}-interaction promoted aggregation of aromatic molecules and energy transfer within Y zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, K.J.; Sunoj, R.B.; Chandrasekhar, J.; Ramamurthy, V.

    2000-05-30

    Photophysical studies of naphthalene confirm that aromatic molecules tend to aggregate within cation exchanged Y zeolites. Ground-state aggregation is traced to the presence of cation-aromatic {pi}-interaction. Solvents that can coordinate to the cation turn off the cation-aromatic interaction, and consequently aggregation does not occur in zeolites that are impregnated with the above solvents. The solvent that exhibits a maximum in such an effect is water. MP2 calculations on cation-benzene dimer indicate that cation-{pi}-interaction results in stabilization of the {pi}-stacked benzene dimer. Results of MP2 calculations are consistent with the formation of ground-state {pi}-stacked aggregates of naphthalene molecules within Y zeolites.

  19. Fabrication of patterned calcium cross-linked alginate hydrogel films and coatings through reductive cation exchange.

    Science.gov (United States)

    Bruchet, Marion; Melman, Artem

    2015-10-20

    Calcium cross-linked alginate hydrogels are widely used in targeted drug delivery, tissue engineering, wound treatment, and other biomedical applications. We developed a method for preparing homogeneous alginate hydrogels cross-linked with Ca(2+) cations using reductive cation exchange in homogeneous iron(III) cross-linked alginate hydrogels. Treatment of iron(III) cross-linked alginate hydrogels with calcium salts and sodium ascorbate results in reduction of iron(III) cations to iron(II) that are instantaneously replaced with Ca(2+) cations, producing homogeneous ionically cross-linking hydrogels. Alternatively, the cation exchange can be performed by photochemical reduction in the presence of calcium chloride using a sacrificial photoreductant. This approach allows fabrication of patterned calcium alginate hydrogels through photochemical patterning of iron(III) cross-linked alginate hydrogel followed by the photochemical reductive exchange of iron cations to calcium.

  20. Probing optical band gaps at nanoscale from tetrahedral cation vacancy defects and variation of cation ordering in NiCo2O4 epitaxial thin films

    Science.gov (United States)

    Dileep, K.; Loukya, B.; Silwal, P.; Gupta, A.; Datta, R.

    2014-10-01

    High resolution electron energy loss spectroscopy (HREELS) is utilized to probe the optical band gaps at the nanoscale in epitaxial NiCo2O4 (NCO) thin films with different structural order (cation/charge). The structure of NCO deviates from the ideal inverse spinel (non-magnetic and insulating) for films grown at higher temperatures (>500 °C) towards a mixed cation structure (magnetic with metallic conductivity) at lower deposition temperatures (<450 °C). This significantly modifies the electronic structure as well as the nature of the band gap of the material. Nanoscale regions with unoccupied tetrahedral A site cations are additionally observed in all the samples and direct measurement from such areas reveals considerably lower band gap values as compared to the ideal inverse spinel and mixed cation configurations. Experimental values of band gaps have been found to be in good agreement with the theoretical mBJLDA exchange potential based calculated band gaps for various cation ordering and consideration of A site cation vacancy defects. The origin of rich variation in cation ordering observed in this system is discussed.

  1. Early events following radiolytic and photogeneration of radical cations in hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Werst, D.W.; Trifunac, A.D.

    1992-11-01

    Real-time studies in hydrocarbons have revealed a richness of chemistry involving the initial ionic species produced in radiolysis and photoionization. A modified radical cation mechanism patterned after the core mechanism for alkane radiolysis-formation of radical cations and their disappearance via ion-molecule reactions - is capable of explaining a wide range of observations in high-energy photochemistry, and thus unifies two high-energy regimes. Fundamental studies of radical cations suggest strategies for mitigating radiation effects in materials.

  2. Early events following radiolytic and photogeneration of radical cations in hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Werst, D.W.; Trifunac, A.D.

    1992-01-01

    Real-time studies in hydrocarbons have revealed a richness of chemistry involving the initial ionic species produced in radiolysis and photoionization. A modified radical cation mechanism patterned after the core mechanism for alkane radiolysis-formation of radical cations and their disappearance via ion-molecule reactions - is capable of explaining a wide range of observations in high-energy photochemistry, and thus unifies two high-energy regimes. Fundamental studies of radical cations suggest strategies for mitigating radiation effects in materials.

  3. Click-based porous cationic polymers for enhanced carbon dioxide capture

    OpenAIRE

    Dani, Alessandro; Magistris, Valentina Crocella Claudio; Santoro, Valentina; Yuan, Jiayin; Bordiga, Silvia

    2017-01-01

    Imidazolium based porous cationic polymers were synthesized using an innovative and facile approach, which takes advantage of the Debus Radziszewski reaction to obtain meso- and microporous polymers following click chemistry principles. In the obtained set of materials, click based porous cationic polymers have the same cationic backbone, whereas they bear the commonly used anions of imidazolium poly(ionic liquid)s. These materials show hierarchical porosity and a good specific surface area. ...

  4. Ternary mixtures of ionic liquids for better salt solubility, conductivity and cation transference number improvement

    Science.gov (United States)

    Karpierz, E.; Niedzicki, L.; Trzeciak, T.; Zawadzki, M.; Dranka, M.; Zachara, J.; Żukowska, G. Z.; Bitner-Michalska, A.; Wieczorek, W.

    2016-10-01

    We hereby present the new class of ionic liquid systems in which lithium salt is introduced into the solution as a lithium cation-glyme solvate. This modification leads to the reorganisation of solution structure, which entails release of free mobile lithium cation solvate and hence leads to the significant enhancement of ionic conductivity and lithium cation transference numbers. This new approach in composing electrolytes also enables even three-fold increase of salt concentration in ionic liquids.

  5. A Photo Touch on Amines: New Synthetic Adventures of Nitrogen Radical Cations.

    Science.gov (United States)

    Maity, Soumitira; Zheng, Nan

    2012-08-01

    Amines have been used as sacrificial electron donors to reduce photoexcited Ru(II) or Ir(III) complexes, during which they are oxidized to nitrogen radical cations. Recently, the synthetic potential of these nitrogen radical cations have caught synthetic organic chemists' attention. They have been exploited in various transformations yielding a number of elegant methods for amine synthesis. This article highlights recent developments on nitrogen radical cation chemistry under visible-light photocatalysis.

  6. Research on plasma and saliva levels of some bivalent cations in patients with chronic periodontitis (salivary cations in chronic periodontitis).

    Science.gov (United States)

    Manea, A; Nechifor, M

    2014-01-01

    The purpose of this study was to determine whether chronic periodontitis can stand behind modifications in the salivary and blood concentration of some bivalent cations (Calcium, Magnesium, Zinc and Copper). For this purpose, we formed a group of 30 adult patients with clinically onset chronic periodontitis, and another one of 30 healthy patients as control. Both groups were free from acute oral pathology and general illnesses. The groups were divided again according to the habit of smoking. Total saliva samples were obtained as "first time in the morning", then weighed and processed. Cations were read on Atomic Absorption Spectrophotometer and by Ion Chromatography (Magnesium). The same patients were required to undergo laboratory blood tests for Calcium, Magnesium and Zinc. Data obtained was normalised, then statistically interpreted using two-tailed heteroscedastic t-Student tests. Our data confirmed the existence of a connection between salivary calcium, magnesium, zinc and copper, and of blood magnesium, and chronic periodontitis. Salivary calcium and magnesium are affected by smoking.

  7. Influence of competing inorganic cations on the ion exchange equilibrium of the monovalent organic cation metoprolol on natural sediment.

    Science.gov (United States)

    Niedbala, Anne; Schaffer, Mario; Licha, Tobias; Nödler, Karsten; Börnick, Hilmar; Ruppert, Hans; Worch, Eckhard

    2013-02-01

    The aim of this study was to systematically investigate the influence of the mono- and divalent inorganic ions Na(+) and Ca(2+) on the sorption behavior of the monovalent organic cation metoprolol on a natural sandy sediment at pH=7. Isotherms for the beta-blocker metoprolol were obtained by sediment-water batch tests over a wide concentration range (1-100000 μg L(-1)). Concentrations of the competing inorganic ions were varied within freshwater relevant ranges. Data fitted well with the Freundlich sorption model and resulted in very similar Freundlich exponents (n=0.9), indicating slightly non-linear behavior. Results show that the influence of Ca(2+) compared to Na(+) is more pronounced. A logarithmic correlation between the Freundlich coefficient K(Fr) and the concentration or activity of the competing inorganic ions was found allowing the prediction of metoprolol sorption on the investigated sediment at different electrolyte concentrations. Additionally, the organic carbon of the sediment was completely removed for investigating the influence of organic matter on the sorption of metoprolol. The comparison between the experiments with and without organic carbon removal revealed no significant contribution of the organic carbon fraction (0.1%) to the sorption of metoprolol on the in this study investigated sediment. Results of this study will contribute to the development of predictive models for the transport of organic cations in the subsurface.

  8. Computational and analytical modeling of cationic lipid-DNA complexes.

    Science.gov (United States)

    Farago, Oded; Grønbech-Jensen, Niels

    2007-05-01

    We present a theoretical study of the physical properties of cationic lipid-DNA (CL-DNA) complexes--a promising synthetically based nonviral carrier of DNA for gene therapy. The study is based on a coarse-grained molecular model, which is used in Monte Carlo simulations of mesoscopically large systems over timescales long enough to address experimental reality. In the present work, we focus on the statistical-mechanical behavior of lamellar complexes, which in Monte Carlo simulations self-assemble spontaneously from a disordered random initial state. We measure the DNA-interaxial spacing, d(DNA), and the local cationic area charge density, sigma(M), for a wide range of values of the parameter (c) representing the fraction of cationic lipids. For weakly charged complexes (low values of (c)), we find that d(DNA) has a linear dependence on (c)(-1), which is in excellent agreement with x-ray diffraction experimental data. We also observe, in qualitative agreement with previous Poisson-Boltzmann calculations of the system, large fluctuations in the local area charge density with a pronounced minimum of sigma(M) halfway between adjacent DNA molecules. For highly-charged complexes (large (c)), we find moderate charge density fluctuations and observe deviations from linear dependence of d(DNA) on (c)(-1). This last result, together with other findings such as the decrease in the effective stretching modulus of the complex and the increased rate at which pores are formed in the complex membranes, are indicative of the gradual loss of mechanical stability of the complex, which occurs when (c) becomes large. We suggest that this may be the origin of the recently observed enhanced transfection efficiency of lamellar CL-DNA complexes at high charge densities, because the completion of the transfection process requires the disassembly of the complex and the release of the DNA into the cytoplasm. Some of the structural properties of the system are also predicted by a continuum

  9. Study on synthesis and flocculation property of cation-polyacrylamide

    Institute of Scientific and Technical Information of China (English)

    NIE Rong-chun; GUO Li-ying; XU Chu-yang

    2008-01-01

    On the basis of flocculating settling experimentation on flotation waste coal in Wangfenggang coal preparation plant, influence of medical dosage and cationization (CD) of CPAM samples on coal slurry's flocculating effect was studied, difference of flocculating effect on coal slurry among different categories of polyacrylamide was discussed. Experi-mental results show that when the dosage of flocculant reaches 2~4 g/m3 flotation waste,and the CD of CPAM is 5%, flocculating effect is the best, light transmittance of super-natant liquor reaches 93%. Taking 3types of sample CPAM, PAM and PHP, which formula weight vary a little, to deal with the same concn of coal slurry, when medicine dosage is 3 g/m3, flocculating effect of CPAM is the best, light transmittance of supernatant liquor reaches 92%.

  10. Organic non-aqueous cation-based redox flow batteries

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, Andrew N.; Vaughey, John T.; Chen, Zonghai; Zhang, Lu; Brushett, Fikile R.

    2016-03-29

    The present invention provides a non-aqueous redox flow battery comprising a negative electrode immersed in a non-aqueous liquid negative electrolyte, a positive electrode immersed in a non-aqueous liquid positive electrolyte, and a cation-permeable separator (e.g., a porous membrane, film, sheet, or panel) between the negative electrolyte from the positive electrolyte. During charging and discharging, the electrolytes are circulated over their respective electrodes. The electrolytes each comprise an electrolyte salt (e.g., a lithium or sodium salt), a transition-metal free redox reactant, and optionally an electrochemically stable organic solvent. Each redox reactant is selected from an organic compound comprising a conjugated unsaturated moiety, a boron cluster compound, and a combination thereof. The organic redox reactant of the positive electrolyte is selected to have a higher redox potential than the redox reactant of the negative electrolyte.

  11. Interpnictogen cations: exploring new vistas in coordination chemistry.

    Science.gov (United States)

    Robertson, Alasdair P M; Gray, Paul A; Burford, Neil

    2014-06-10

    Pnictine derivatives can behave as both 2e(-) donors (Lewis bases) and 2e(-) acceptors (Lewis acids). As prototypical ligands in the coordination chemistry of transition metals, amines and phosphines also form complexes with p-block Lewis acids, including a variety of pnictogen-centered acceptors. The inherent Lewis acidity of pnictogen centers can be enhanced by the introduction of a cationic charge, and this feature has been exploited in recent years in the development of compounds resulting from coordinate Pn-Pn and Pn-Pn' interactions. These compounds offer the unusual opportunity for homoatomic coordinate bonding and the development of complexes that possess a lone pair of electrons at the acceptor center. This Review presents new directions in the systematic extension of coordination chemistry from the transition series into the p-block.

  12. A New Nanometer-Sized Ga(III-Oxyhydroxide Cation

    Directory of Open Access Journals (Sweden)

    William H. Casey

    2015-02-01

    Full Text Available A new 30-center Ga(III-oxy-hydroxide cation cluster was synthesized by hydrolysis of an aqueous GaCl3 solution near pH = 2.5 and crystallized using 2,6-napthalene disulfonate (NDS. The cluster has 30 metal centers and a nominal stoichiometry: [Ga30(μ4-O12(μ3-O4(μ3-OH4(μ2-OH42(H2O16](2,6-NDS6, where 2,6-NDS = 2,6-napthalene disulfonate This cluster augments the very small library of Group 13 clusters that have been isolated from aqueous solution and closely resembles one other Ga(III cluster with 32 metal centers that had been isolated using curcurbit ligands. These clusters have uncommon linked Ga(O4 centers and sets of both protonated and unprotonated μ3-oxo.

  13. Ab initio study of the transition-metal carbene cations

    Institute of Scientific and Technical Information of China (English)

    李吉海; 冯大诚; 冯圣玉

    1999-01-01

    The geometries and bonding characteristics of the first-row transition-metal carbene cations MCH2+ were investigated by ab initio molecular orbital theory (HF/LANL2DZ). All of MCH2+ are coplanar. In the closed shell structures the C bonds to M with double bonds; while in the open shell structures the partial double bonds are formed, because one of the σ and π orbitals is singly occupied. It is mainly the π-type overlap between the 2px orbital of C and 4px, 3dxz, orbitals of M+ that forms the π orbitals. The dissociation energies of C—M bond appear in periodic trend from Sc to Cu. Most of the calculated bond dissociation energies are close to the experimental ones.

  14. Cationic Conjugated Polymers-Induced Quorum Sensing of Bacteria Cells.

    Science.gov (United States)

    Zhang, Pengbo; Lu, Huan; Chen, Hui; Zhang, Jiangyan; Liu, Libing; Lv, Fengting; Wang, Shu

    2016-03-15

    Bacteria quorum sensing (QS) has attracted significant interest for understanding cell-cell communication and regulating biological functions. In this work, we demonstrate that water-soluble cationic conjugated polymers (PFP-G2) can interact with bacteria to form aggregates through electrostatic interactions. With bacteria coated in the aggregate, PFP-G2 can induce the bacteria QS system and prolong the time duration of QS signal molecules (autoinducer-2 (AI-2)) production. The prolonged AI-2 can bind with specific protein and continuously regulate downstream gene expression. Consequently, the bacteria show a higher survival rate against antibiotics, resulting in decreased antimicrobial susceptibility. Also, AI-2 induced by PFP-G2 can stimulate 55.54 ± 12.03% more biofilm in E. coli. This method can be used to understand cell-cell communication and regulate biological functions, such as the production of signaling molecules, antibiotics, other microbial metabolites, and even virulence.

  15. Efficient intravesical therapy of bladder cancer with cationic doxorubicin nanoassemblies.

    Science.gov (United States)

    Jin, Xun; Zhang, Peilan; Luo, Li; Cheng, Hao; Li, Yunzu; Du, Ting; Zou, Bingwen; Gou, Maling

    Nanoparticles have promising applications in drug delivery for cancer therapy. Herein, we prepared cationic 1,2-dioleoyl-3-trimethylammonium propane/methoxypoly (ethyleneglycol) (DPP) nanoparticles to deliver doxorubicin (Dox) for intravesical therapy of bladder cancer. The DPP micelles have a mean dynamic diameter of 18.65 nm and a mean zeta potential of +19.6 mV. The DPP micelles could prolong the residence of Dox in the bladder, enhance the penetration of Dox into the bladder wall, and improve cellular uptake of Dox. The encapsulation by DPP micelles significantly improved the anticancer effect of Dox against orthotopic bladder cancer in vivo. This work described a Dox-loaded DPP nanoparticle with potential applications in intravesical therapy of bladder cancer.

  16. Chiral DNA packaging in DNA-cationic liposome assemblies.

    Science.gov (United States)

    Zuidam, N J; Barenholz, Y; Minsky, A

    1999-09-03

    Recent studies have indicated that the structural features of DNA-lipid assemblies, dictated by the lipid composition and cationic lipid-to-DNA ratio, critically affect the efficiency of these complexes in acting as vehicles for cellular delivery of genetic material. Using circular dichroism we find that upon binding DNA, positively-charged liposomes induce a secondary conformational transition of the DNA molecules from the native B form to the C motif. Liposomes composed of positively-charged and neutral 'helper' lipids, found to be particularly effective as transfecting agents, induce - in addition to secondary conformational changes - DNA condensation into a left-handed cholesteric-like phase. A structural model is presented according to which two distinct, yet inter-related modes of DNA packaging coexist within such assemblies. The results underline the notion that subtle changes in the components of a supramolecular assembly may substantially modulate the interplay of interactions which dictate its structure and functional properties.

  17. Investigation on the aggregation properties of cationic [60]fullerene derivative

    Institute of Scientific and Technical Information of China (English)

    WANG Guanwu; ZHAO Guoxia; YAN Lifeng

    2004-01-01

    The UV-Vis spectra, HRTEM and AFM images of cationic fullerene derivative 1 with ammonium head group directly connected to C60 skeleton in tetrahydrofuran (THF)-water (H2O) binary mixtures and in pure H2O were investigated. It was found that the UV-Vis spectra of ammonium 1 in the THF-H2O mixtures with THF% ≥ 20% were nearly overlapped, while those with THF% < 20% showed broadened and red-shifted peaks, indicating the formation of aggregates. Corresponding to the UV-Vis spectral changes,the solvatochromism of ammonium 1 in THF-H2O mixtures was observed. Ammonium 1 in binary THF-H2O mixtures existing as the monomer state could aggregate upon prolonged standing. Higher temperature and lower concentration speeded up the aggregation process.

  18. Quantitative mapping of intracellular cations in the human amniotic membrane

    Science.gov (United States)

    Moretto, Ph.; Llabador, Y.; Simonoff, M.; Razafindrabe, L.; Bara, M.; Guiet-Bara, A.

    1993-05-01

    The effect of magnesium and taurine on the permeability of cell membranes to monovalent cations has been investigated using the Bordeaux nuclear microprobe. PIXE and RBS techniques have been used to provide quantitative measurements and ion distributions in the isolated amniotic membrane. This physiological model for cellular exchanges allowed us to reveal the distribution of most elements involved in cellular pathways and the modifications under different experimental conditions of incubation in physiological fluids. The PIXE microanalysis provided an original viewpoint on these mechanisms. Following this first study, the amnion compact lamina was found to play a role which was not, up to now, taken into account in the interpretation of electrophysiological experimentations. The release of some ionic species, such as K +, from the epithelial cells, during immersion in isotonic fluids, could have been hitherto underestimated.

  19. Electrochemical uranyl cation biosensor with DNA oligonucleotides as receptor layer.

    Science.gov (United States)

    Jarczewska, Marta; Ziółkowski, Robert; Górski, Łukasz; Malinowska, Elżbieta

    2014-04-01

    The present study aims at the further development of the uranyl oligonucleotide-based voltammetric biosensor, which takes advantage of strong interaction between UO2(2+) and phosphate DNA backbone. Herein we report the optimization of working parameters of previously elaborated electrochemical DNA biosensor. It is shown that the sensor sensitivity is highly dependent on the oligonucleotide probe length and the incubation time of sensor in a sample solution. Consequently, the highest sensitivity was obtained for 10-nucleotide sequence and 60 min incubation time. The lower detection limit towards uranyl cation for developed biosensor was 30 nM. The influence of mixed monolayers and the possibility of developing a non-calibration device were also investigated. The selectivity of the proposed biosensor was significantly improved via elimination of adenine nucleobases from the DNA probe. Moreover, the regeneration procedure was elaborated and tested to prolong the use of the same biosensor for 4 subsequent determinations of UO2(2+).

  20. Cation-Induced Coiling of Vanadium Pentoxide Nanobelts

    Directory of Open Access Journals (Sweden)

    Liu Jun

    2010-01-01

    Full Text Available Abstract Single-crystalline V2O5·xH2O nanorings and microloops were chemically assembled via an ion-induced chemical spinning route in the designed hydrothermal system. The morphology and structure of products were investigated by means of scanning electron microscopy (SEM and transmission electron microscopy (TEM. X-ray powder diffraction (XRD measurement, energy-dispersive X-ray spectroscopy (EDS microanalysis and thermal gravimetric analysis (TGA revealed that the composition of nanorings and microloops is V2O5·1·1H2O. For these oxide nanorings and microloops, the cation-induced coiling growth mechanism of vanadium pentoxide nanobelts has been proposed on the basis of crystallographic structure of vanadium pentoxide. Our proposed chemical spinning process and the rational solution-phase synthesis route can also be extended to prepare novel 1D materials with layered or more complex structures.

  1. A spectroscopic study of interaction of cationic dyes with heparin

    Directory of Open Access Journals (Sweden)

    R. Nandini

    2010-01-01

    Full Text Available The interaction of two cationic dyes namely, acridine orange and pinacyanol chloride with an anionic polyelectrolyte, heparin, has been investigated by spectrophotometric method.The polymer induced metachromasy in the dyes resulting in the shift of the absorption maxima of the dyes towards shorter wavelengths. The stability of the complexes formed between acridine orange and heparin was found to be lesser than that formed between pinacyanol chloride and heparin. This fact was further confirmed by reversal studies using alcohols, urea and surfactants. The interaction of acridine orange with heparin has also been investigated fluorimetrically.The interaction parameters revealed that binding between acridine orange and heparin arises due to electrostatic interaction while that between pinacyanol chloride and heparin is found to involve both electrostatic and hydrophobic forces. The effect of the structure of the dye in inducing metachromasy has also been discussed.

  2. Aqueous behaviour of cationic surfactants containing a cleavable group.

    Science.gov (United States)

    Samakande, Austin; Chaghi, Radhouane; Derrien, Gaelle; Charnay, Clarence; Hartmann, Patrice C

    2008-04-01

    The aggregation behaviour of two novel cationic RAFT agents (transfer surfactants); N,N-dimethyl-N-(4-(((phenylcarbonothioyl)thio)methyl)benzyl)ethanammonium bromide (PCDBAB) and N-(4-((((dodecylthio)-carbonothioyl)thio)methyl)benzyl)-N,N-dimethylethanammonium bromide (DCTBAB) in diluted solutions have been investigated by surface tension, conductimetry and microcalorimetry measurements. The thermodynamic parameters i.e. the critical micelle concentration (cmc), the degree of micelle ionization (alpha), the head group surface area (a 0), Delta H mic, Delta G mic and T Delta S mic are reported at 303 K. The thermodynamic parameters have been compared to those of the conventional surfactant cetyltrimethylammonium bromide (CTAB) in order to specify structural relationships. The obtained results have been discussed considering the hydrophobic behaviour of the S-C=S- linkage and the specific interactions that arise from the introduction of the benzene ring into the hydrophobic part.

  3. Note: Vibrationally mediated photodissociation of carbon dioxide cation

    Science.gov (United States)

    Mao, Rui; Zhang, Qun; Chen, Min; He, Chao; Zhou, Dan-na; Bai, Xi-lin; Zhang, Limin; Chen, Yang

    2013-10-01

    The photodissociation dynamics of carbon dioxide cation, CO_2^ +, mediated by its different tilde A{}^2Π _{u,1/2} (\\upsilon _1,\\upsilon _2,0) vibronic states has been investigated by means of time-sliced velocity map imaging. Through analysis of the recorded translational energy release spectra of photofragment CO+, we found that the photodissociation of CO_2^ + exhibits drastic change in a rather narrow energy region. A conformational barrier in the CO_2^ + ( {tilde A{}^2A_1 } ) state is suggested to be ˜5600 cm-1 relative to the CO_2^ + ( {tilde A{}^2Π _{u,1/2} ( {0,0,0} )}) state, in reasonable agreement with previous prediction.

  4. Influence of hydration and cation binding on parvalbumin dynamics

    Science.gov (United States)

    Zanotti, J.-M.; Parello, J.; Bellissent-Funel, M.-C.

    Due to structural characteristics, parvalbumin exerts a major role in intracellular Mg2+ and Ca2+ concentration regulation during the muscular contraction-relieving cycle. This structure-function relationship being established, we are investigating the structure-dynamics-function relationship to take into account the protein dynamics. Because of the strong incoherent neutron scattering cross section of hydrogen and of the abundance of this element in proteins, incoherent inelastic neutron scattering is a unique probe to study vibrations and localised motions in biological macromolecules. We take advantage of the complementarities in energy or time resolution of various neutron spectrometers (time of flight, backscattering, spin-echo) to probe the parvalbumin dynamics from a fraction of a picosecond to a few nanoseconds. Influences of hydration and of the nature of the cation on parvalbumin dynamics are discussed.

  5. Property Predictions for Nitrate Salts with Nitroxy-Functionalized Cations

    Science.gov (United States)

    2011-05-01

    2-nitroxyethyl)-3-methyl-5-nitroim+ (40) 1-(2-nitroxyethyl)-5-nitroimidazole (40a) CH3X Pyrazolium Cations 1,2H-pyr+ (41) 1H- pyrazole (41a/44a) HX...4-nitro-1,2H-pyr+ (42) 4-nitro-1H- pyrazole (42a) HX 3,5-bis(nitroxymethyl)-1,2H-pyr+ (43) 3,5-bis(nitroxymethyl)-1H- pyrazole (43a) HX 1-methyl-2H...pyr+ (44) 1H- pyrazole (41a/44a) CH3X 1,2-dimethylpyr+ (45) 1-methylpyrazole (45a) CH3X 1-nitroxymethyl-2-methylpyr+ (46) 1-nitroxymethylpyrazole (46a

  6. Cationic Dihydrogen/Dihydride Complexes of Osmium: Structure and Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Egbert, Jonathan D.; Bullock, R. Morris; Heinekey, D. M.

    2007-03-22

    Reaction of Cp*Os(CO)2Cl with (Et3Si )(BArF4) under hydrogen gas affords the cationic hydrogen complex [Cp*Os(CO)2(H2)][BArF4] (1), (Cp* = C5Me5; ArF = C6F5). When this reaction is carried out with HD gas, complex 1-d1 results, with JHD = 24.5 Hz. When solutions of complex 1 are monitored by 1H NMR spectroscopy over several days, the gradual formation of a trans dihydride species is observed. Similarly, reaction of CpOs(dppm)Br with NaBArF*4 (ArF* = 3,5-(CF3)2C6H3) under hydrogen affords the cationic dihydride complex [CpOs(dppm)H2]BArF*4 (2). At 295 K, complex 2 exists as a 10:1 mixture of cis and trans isomers. The 1H NMR spectrum of the cis form in the hydride region exhibits a triplet with JHP = 6.5 Hz, due to rapid exchange of the hydrogen atoms. At low temperature, static spectra of the HH'PP' spin system can be obtained, revealing quantum mechanical exchange coupling between the two hydride ligands. The observed JHH' is temperature dependent, varying from 133 Hz at 141 K to 176 Hz at 198 K. This is the first report of detectable exchange coupling between pairs of chemically equivalent hydrogen atoms. Research at the University of Washington was supported by the National Science Foundation. Research at Brookhaven National Laboratory was carried out under contract DE-AC02-98CH10886 with the U.S. Department of Energy and was supported by its Division of Chemical Sciences, Office of Basic Energy Sciences. Research at Pacific Northwest National Laboratory (PNNL) was funded by LDRD funds. PNNL is operated by Battelle for the US Department of Energy.

  7. Non-Surface Activity of Cationic Amphiphilic Diblock Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, Rati Ranjan; Yamada, Tasuku; Matsuoka, Hideki, E-mail: ratiranjan@immt.res.in, E-mail: matsuoka@star.polym.kyoto-u.ac.jp [Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2011-09-19

    Cationic amphiphilic diblock copolymers containing quaternized poly (2-vinylpyridine) chain as a hydrophilic segment (PIp-b-PNMe2VP) were synthesized by living anionic polymerization. By IR measurement, we confirmed the quaternization of the polymer (PIp-b-PNMe2VP), and determined the degree of quaternization by conductometric titration. The surface tension experiment showed that the polymers are non-surface active in nature. The foam formation of the polymer solutions was also investigated with or without added salt. Almost no foam formation behavior was observed without added salt, while a little foam was observed in the presence of 1M NaCl. The critical micelle concentration (cmc) of the diblock copolymers with 3 different chain lengths was measured by the static light scattering method. The cmc values obtained in this study were much lower than the values obtained for anionic non-surface active diblock polymers studied previously. The hydrodynamic radii of the polymer micelle increased slightly in the presence of 1 M NaCl. The transmission electron microscopic images revealed spherical micelles in pure water. In the presence of salt, the cmc values increased as was the case for anionic polymers, which is unlike conventional surfactant systems but consistent with non-surface active anionic block copolymers. The microviscosity of the micelle core was evaluated using Coumarin-153 as a fluorescent anisotropy probe using steady-sate fluorescence depolarization. Non-surface activity has been proved to be universal for ionic amphiphilic block copolymers both for anionic and cationic. Hence, the origin of non-surface activity is not the charged state of water surface itself, but should be an image charge repulsion at the air/water interface.

  8. Dilution thermodynamics of the biologically relevant cation mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Kaczyński, Marek, E-mail: marek.kaczynski@pwr.wroc.pl; Borowik, Tomasz, E-mail: office@novel-id.pl; Przybyło, Magda, E-mail: magdalena.przybylo@pwr.wroc.pl; Langner, Marek, E-mail: marek.langner@pwr.wroc.pl

    2014-01-10

    Graphical abstract: - Highlights: • Dilution energetics of Ca{sup 2+} can be altered by the aqueous phase ionic composition. • Dissipated heat upon Ca{sup 2+} dilution is drastically reduced in the K{sup +} presence. • Reduction of the enthalpy change upon Ca{sup 2+} dilution is K{sup +} concentration dependent. • The cooperativity of Ca{sup 2+} hydration might be of great biological relevance providing a thermodynamic argument for the specific ionic composition of the intracellular environment. - Abstract: The ionic composition of intracellular space is rigorously controlled by a variety of processes consuming large quantities of energy. Since the energetic efficiency is an important evolutional criterion, therefore the ion fluxes within the cell should be optimized with respect to the accompanying energy consumption. In the paper we present the experimental evidence that the dilution enthalpies of the biologically relevant ions; i.e. calcium and magnesium depend on the presence of monovalent cations; i.e. sodium and potassium. The heat flow generated during the dilution of ionic mixtures was measured with the isothermal titration calorimetry. When calcium was diluted together with potassium the dilution enthalpy was drastically reduced as the function of the potassium concentration present in the solution. No such effect was observed when the potassium ions were substituted with sodium ones. When the dilution of magnesium was investigated the dependence of the dilution enthalpy on the accompanying monovalent cation was much weaker. In order to interpret experimental evidences the ionic cluster formation is postulated. The specific organization of such cluster should depend on ions charges, sizes and organization of the hydration layers.

  9. Binding properties of oxacalix[4]arenes derivatives toward metal cations; Interactions entre cations metalliques et derives des oxacalix[4]arenes

    Energy Technology Data Exchange (ETDEWEB)

    Mellah, B

    2006-11-15

    The objective of this work was to establish the binding properties of oxacalix[4]arene derivatives with different numbers of the oxa bridges, functional groups (ketones, pyridine, ester, amide and methoxy) and conformations. Their interactions with alkali and alkaline-earth, heavy and transition metal cations have been evaluated according to different approaches: (i) extraction of corresponding picrates from an aqueous phase into dichloromethane; (ii) determination of the thermodynamic parameters of complexation in methanol and/or acetonitrile by UV-spectrophotometry and micro-calorimetry; (iii) determination of the stoichiometry of the complexes by ESI-MS; (iv) {sup 1}H-NMR titrations allowing to localize the metal ions in the ligand cavity. In a first part dealing on homo-oxacalix[4]arenes, selectivities for Na{sup +}, K{sup +}, Ca{sup 2+}, Pb{sup 2+} and Mn{sup 2+} of ketones derivatives was shown. The presence of oxa bridge in these derivatives increases their efficiency while decreasing their selectivity with respect to related calixarenes. The pyridine derivative prefers transition and heavy metal cations, in agreement with the presence of the soft nitrogen atoms. In the second part, di-oxacalix[4]arene ester and secondary amide derivatives were shown to be less effective than tertiary amide counterparts but to present high selectivities for Li{sup +}, Ba{sup 2+}, Zn{sup 2+} and Hg{sup 2+}. A third part devoted to the octa-homo-tetra-oxacalix[4]arene tetra-methoxy shows that the 1:1 metal complexes formed are generally more stable than those of calixarenes, suggesting the participation of the oxygen atoms of the bridge in the complexation. Selectivity for Cs{sup +}, Ba{sup 2+}, Cu{sup 2+} and Hg{sup 2+} were noted. (author)

  10. Coordination Chemistry of Alkali and Alkaline-Earth Cations with Macrocyclic Ligands.

    Science.gov (United States)

    Dietrich, Bernard

    1985-01-01

    Discusses: (l) alkali and alkaline-earth cations in biology (considering naturally occurring lonophores, their X-ray structures, and physiochemical studies); (2) synthetic complexing agents for groups IA and IIA; and (3) ion transport across membranes (examining neutral macrobicyclic ligands as metal cation carriers, transport by anionic carriers,…

  11. Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations

    Directory of Open Access Journals (Sweden)

    María del Valle Martínez de Yuso

    2014-04-01

    Full Text Available Surface and bulk changes in a Nafion membrane as a result of IL-cation doping (1-butyl-3-methylimidazolium tetrafluoroborate or BMIM+BF4 and phenyltrimethylammonium chloride or TMPA+Cl− were studied by X-ray photoelectron spectroscopy (XPS, contact angle, differential scanning calorimetry (DSC and impedance spectroscopy (IS measurements performed with dry samples after 24 h in contact with the IL-cations BMIM+ and TMPA+. IL-cations were selected due to their similar molecular weight and molar volume but different shape, which could facilitate/obstruct the cation incorporation in the Nafion membrane structure by proton/cation exchange mechanism. The surface coverage of the Nafion membrane by the IL-cations was confirmed by XPS analysis and contact angle, while the results obtained by the other two techniques (DSC and IS seem to indicate differences in thermal and electrical behaviour depending on the doping-cation, being less resistive the Nafion/BMIM+ membrane. For that reason, determination of the ion transport number was obtained for this membrane by measuring the membrane or concentration potential with the samples in contact with HCl solutions at different concentrations. The comparison of these results with those obtained for the original Nafion membrane provides information on the effect of IL-cation BMIM+ on the transport of H+ across wet Nafion/BMIM+ doped membranes.

  12. SEQUESTRATION OF ORGANIC CATIONS BY ACIDIFIED HEPATIC ENDOCYTIC VESICLES AND IMPLICATIONS FOR BILIARY-EXCRETION

    NARCIS (Netherlands)

    VANDYKE, RW; FABER, ED; MEIJER, DKF

    1992-01-01

    A number of cationic amine drugs that are taken up by liver and excreted into bile may accumulate in acidified intracellular organelles such as lysosomes and endosomes. These studies were undertaken to assess directly the uptake and accumulation of three types of model organic cationic amines by end

  13. Chemical mechanical polishing of transparent conductive layers using spherical cationic polymer microbeads

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, Shoji, E-mail: nagaoka@kmt-iri.go.jp [Kumamoto Industrial Research Institute, 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Chuouku, Kumamoto 860-8555 (Japan); Kumamoto Institute for Photo-Electro Organics (Phoenics), 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Ryu, Naoya [Kumamoto Industrial Research Institute, 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Yamanouchi, Akio [Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Chuouku, Kumamoto 860-8555 (Japan); Shirosaki, Tomohiro [Kumamoto Industrial Research Institute, 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Kumamoto Institute for Photo-Electro Organics (Phoenics), 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Horikawa, Maki [Kumamoto Industrial Research Institute, 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Chuouku, Kumamoto 860-8555 (Japan); Kumamoto Institute for Photo-Electro Organics (Phoenics), 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Sakurai, Hideo; Takafuji, Makoto; Ihara, Hirotaka [Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Chuouku, Kumamoto 860-8555 (Japan); Kumamoto Institute for Photo-Electro Organics (Phoenics), 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan)

    2015-02-02

    Spherical cationic polymer microbeads were used to chemically mechanically polish transparent conductive oxide (TCO) layers without the need for inorganic abrasives. Poly(methyl acrylate) (PMA) was used as the polymer matrix. Surface cationization of the spherical PMA microbeads was achieved by aminolysis using 1,2-diaminoethane. The amino group content of the microbeads was controlled using the aminolysis reaction time. The surface roughness of the TCO polished using the cationic polymer microbeads was similar to that of TCO polished with an inorganic abrasive. The microbead-polished TCO layer was slightly thinner than the unpolished TCO layer. The sheet resistance of the TCO layer polished using the microbeads was lower than that polished using the inorganic abrasive. The TCO polishing ability of the microbeads was dependent on their cationic properties and softness. - Highlights: • Indium tin oxide (ITO) layer was planarized using cationic polymer microbeads. • Cationic polymer microbeads planarized, while retaining ITO layer thickness • Cationic polymer microbeads did not degrade the sheet resistance of ITO. • Cationic polymer microbeads could planarize the ITO surface without damaging.

  14. Concerted action of two cation filters in the aquaporin water channel

    DEFF Research Database (Denmark)

    Wu, Binghua; Steinbronn, Christina; Alsterfjord, Magnus;

    2009-01-01

    Aquaporin (AQP) facilitated water transport is common to virtually all cell membranes and is marked by almost perfect specificity and high flux rates. Simultaneously, protons and cations are strictly excluded to maintain ionic transmembrane gradients. Yet, the AQP cation filters have not been ide...

  15. Structures of dioxobipyridil-12-crown-4 and its complexes with silver (I) and copper (II) cations

    Science.gov (United States)

    Starova, Galina L.; Denisova, Anna S.; Dem'yanchuk, Evgeniya M.

    2008-02-01

    The structures of dioxobipyridil-12-crown-4 ( bpy-CO-crown) and its complexes with copper (II) and silver (I) cations have been determined using single crystal X-ray-diffraction. The results have been compared with the literature data on the complexes of dcmbpy and its complex with silver (I) and copper (II) cations.

  16. Synthesis of phosphorylated calix[4]arene derivatives for the design of solid phases immobilizing uranyl cations

    Energy Technology Data Exchange (ETDEWEB)

    Maroun, E.B.; Hagege, A.; Asfari, Z. [Laboratoire de Chimie Analytique et Minerale, UMR 7178 ULP/CNRS/IN2P3 LC4, ECPM, Strasbourg Cedex (France); Basset, CH.; Quemeneur, E.; Vidaud, C. [CEA IBEB, SBTN, Centre de Marcoule, Bagnols-sur-Ceze (France)

    2009-07-01

    With the aim of developing supports for uranyl cations immobilisation, new 1, 3-alternate calix[4]arenes bearing both phosphonic acid functions as chelating sites and N-succinimide-4-oxa-butyrate as the anchoring arm were synthesised in good yields. The coupling of such calixarenes to a gel was performed and a successful immobilisation of uranyl cations was obtained. (authors)

  17. A Cationic Diode Based on Asymmetric Nafion® Film Deposits

    NARCIS (Netherlands)

    He, Daping; Madrid, Elena; Aaronson, Barak; Fan, Lian; Doughty, James; Mathwig, Klaus; Bond, Alan M; McKeown, Neil B; Marken, Frank

    2017-01-01

    A thin film of Nafion®, of approximately 5 microm thickness, asymmetrically deposited onto a 6 microm thick film of poly(ethylene terephthalate) (PET) fabricated with a 5, 10, 20, or 40 microm microhole, is shown to exhibit prominent ionic diode behaviour involving cation charge carrier ("cationic d

  18. Base cation deposition in Europe - Part II. Acid neutralization capacity and contribution to forest nutrition

    NARCIS (Netherlands)

    Draaijers, G.P.J.; Leeuwen, E.P. van; Jong, P.G.H. de; Erisman, J.W.

    1997-01-01

    An assessment was made of the capacity of base cations to neutralize acid deposition and of the contribution of base cation deposition to forest nutrition in Europe. In large parts of southern Europe more than 50% of the potential acid deposition was found counteracted by deposition of non-sea salt

  19. Real-Time Observation of Organic Cation Reorientation in Methylammonium Lead Iodide Perovskites

    NARCIS (Netherlands)

    Bakulin, Artem A.; Selig, Oleg; Bakker, Huib J.; Rezus, Yves L. A.; Mueller, Christian; Glaser, Tobias; Lovrincic, Robert; Sun, Zhenhua; Chen, Zhuoying; Walsh, Aron; Frost, Jarvist M.; Jansen, Thomas L. C.

    2015-01-01

    The introduction of a mobile and polarized organic moiety as a cation in 3D lead-iodide perovskites brings fascinating optoelectronic properties to these materials. The extent and the time scales of the orientational mobility of the organic cation and the molecular mechanism behind its motion remain

  20. Eutrophication of mangroves linked to depletion of foliar and soil base cations.

    Science.gov (United States)

    Fauzi, Anas; Skidmore, Andrew K; Heitkönig, Ignas M A; van Gils, Hein; Schlerf, Martin

    2014-12-01

    There is growing concern that increasing eutrophication causes degradation of coastal ecosystems. Studies in terrestrial ecosystems have shown that increasing the concentration of nitrogen in soils contributes to the acidification process, which leads to leaching of base cations. To test the effects of eutrophication on the availability of base cations in mangroves, we compared paired leaf and soil nutrient levels sampled in Nypa fruticans and Rhizophora spp. on a severely disturbed, i.e. nutrient loaded, site (Mahakam delta) with samples from an undisturbed, near-pristine site (Berau delta) in East Kalimantan, Indonesia. The findings indicate that under pristine conditions, the availability of base cations in mangrove soils is determined largely by salinity. Anthropogenic disturbances on the Mahakam site have resulted in eutrophication, which is related to lower levels of foliar and soil base cations. Path analysis suggests that increasing soil nitrogen reduces soil pH, which in turn reduces the levels of foliar and soil base cations in mangroves.

  1. Modification of potato peel waste with base hydrolysis and subsequent cationization.

    Science.gov (United States)

    Lappalainen, Katja; Kärkkäinen, Johanna; Joensuu, Päivi; Lajunen, Marja

    2015-11-01

    Potato peel waste (PW) is a starch containing biomaterial produced in large amounts by food processing industry. In this work, the treatment of PW by alkaline hydrolysis and cationization in the water phase is reported. In order to improve the cationization of starch, PW was hydrolyzed by heating with alkaline (NaOH) ethanol solution (80%) in a water bath. The impact of variable molar ratios of anhydroglucose unit (AGU):NaOH, heating temperatures and times was studied on the degradation of starch and the molecular size distribution of the product. The hydrolyzed PW was cationized subsequently in water by using glycidyltrimethylammonium chloride and catalyzed by NaOH under microwave irradiation or in an oil bath. The impact of the various reaction conditions on the cationization and degree of substitution of starch was studied. The degree of substitution of the cationized starch varied in the range of 0-0.35.

  2. Theoretical Investigation on the Adsorption of Ag+ and Hydrated Ag+ Cations on Clean Si(111)Surface

    Institute of Scientific and Technical Information of China (English)

    SHENG Yong-Li; LI Meng-Hua; WANG Zhi-Guo; LIU Yong-Jun

    2008-01-01

    In this paper,the adsorption of Ag+ and hydrated Ag+ cations on clean Si(111)surface were investigated by using cluster(Gaussian 03)and periodic(DMol3)ab initio calculations.Si(111)surface was described with cluster models(Si14H17 and Si22H21)and a four-silicon layer slab with periodic boundary conditions.The effect of basis set superposition error(BSSE)was taken into account by applying the counterpoise correction.The calculated results indicated that the binding energies between hydrated Ag+ cations and clean Si(111)surface are large,suggesting a strong interaction between hydrated Ag+ cations and the semiconductor surface.With the increase of number,water molecules form hydrogen bond network with one another and only one water molecule binds directly to the Ag+ cation.The Ag+ cation in aqueous solution will safely attach to the clean Si(111)surface.

  3. THE INFLUENCE OF CATIONIZED BIRCH XYLAN ON WET AND DRY STRENGTH OF FINE PAPER

    Directory of Open Access Journals (Sweden)

    Janne Kataja-aho,

    2012-02-01

    Full Text Available Cationized birch xylan was prepared and its use as a papermaking chemical was evaluated. The focus was on studying the effects of cationized birch xylan on the wet and dry strength of fine paper. The results of the laboratory experiments show that the addition of 3 percent of cationized birch xylan to birch kraft pulp improved the initial wet strength of the web by 30 percent compared to base stock at a solids content of 55%. Furthermore, the tensile stiffness of the wet web increased by approximately a third and the dry tensile strength improved by 26%, while the dry elastic modulus was not changed. The improvements in the strength properties were clear when compared to the base stock, but not as high as achieved with conventionally used cationized starch. The difference between the xylan and starch is most likely due to the shorter polymer chain length of the cationized xylan.

  4. Magnetic Resonance Studies of Proton Loss from Carotenoid Radical Cations

    Energy Technology Data Exchange (ETDEWEB)

    Kispert, Lowell D [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Focsan, A Ligia [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Konovalova, Tatyana A [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lawrence, Jesse [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bowman, Michael K [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dixon, David A [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Molnar, Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deli, Jozsef [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2007-06-11

    Carotenoids, intrinsic components of reaction centers and pigment-protein complexes in photosynthetic membranes, play a photoprotective role and serve as a secondary electron donor. Before optimum use of carotenoids can be made in artificial photosynthetic systems, their robust nature in living materials requires extensive characterization of their electron transfer, radical trapping ability, stability, structure in and on various hosts, and photochemical behavior. Pulsed ENDOR and 2D-HYSCORE studies combined with DFT calculations reveal that photo-oxidation of natural zeaxanthin (I) and violaxanthin (II) on silica-alumina produces not only the carotenoid radical cations (Car•+) but also neutral radicals (#Car•) by proton loss from the methyl groups at positions 5 or 5', and possibly 9 or 9' and 13 or 13'. Notably, the proton loss favored in I at the 5 position by DFT calculations, is unfavorable in II due to the epoxide at the 5, 6 position. DFT calculations predict the isotropic methyl proton couplings of 8-10 MHz for Car•+ which agree with the ENDOR for carotenoid α-conjugated radical cations. Large α-proton hyperfine coupling constants (>10 MHz) determined from HYSCORE are assigned from the DFT calculations to neutral carotenoid radicals. Proton loss upon photolysis was also examined as a function of carotenoid polarity [Lycopene (III) versus 8'-apo-β-caroten-8'-al (IV)]; hydrogen bonding [Lutein (V) versus III]; host [silica-alumina versus MCM-41 molecular sieve]; and substituted metal in MCM-41. Loss of H+ from the 5(5'), 9(9') or 13(13') methyl positions has importance in photoprotection. Photoprotection involves nonphotochemical quenching (NPQ) in which 1Ch1* decays via energy transfer to the carotenoid which returns to the ground state by thermal dissipation; or via electron transfer to form a charge transfer state (I •+…Chl•-), lower in energy than 1Chl*. Formation of I •+ results in bond

  5. Cation immobilization in pyrolyzed simulated spent ion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Luca, Vittorio, E-mail: vluca@cnea.gov.ar [Programa Nacional de Gestion de Residuos Radiactivos, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. General, Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); Bianchi, Hugo L. [Gerencia de Quimica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. General, Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); ECyT, Universidad Nacional de General San Martin, Campus Miguelete, Ed. Tornavias, Martin de Irigoyen 3100, 1650 San Martin (Argentina); Conicet, Av. Rivadavia 1917, 1033 Buenos Aires (Argentina); Manzini, Alberto C. [Programa Nacional de Gestion de Residuos Radiactivos, Comision Nacional de Energia Atomica, Av. Del Libertador 8250, CP 1429, Ciudad Autonoma de Buenos Aires (Argentina)

    2012-05-15

    Significant quantities of spent ion exchange resins that are contaminated by an assortment of radioactive elements are produced by the nuclear industry each year. The baseline technology for the conditioning of these spent resins is encapsulation in ordinary Portland cement which has various shortcomings none the least of which is the relatively low loading of resin in the cement and the poor immobilization of highly mobile elements such as cesium. The present study was conducted with cationic resin samples (Lewatit S100) loaded with Cs{sup +}, Sr{sup 2+}, Co{sup 2+}, Ni{sup 2+} in roughly equimolar proportions at levels at or below 30% of the total cation exchange capacity. Low temperature thermal treatment of the resins was conducted in inert (Ar), or reducing (CH{sub 4}) gas atmospheres, or supercritical ethanol to convert the hydrated polymeric resin beads into carbonaceous materials that contained no water. This pyrolytic treatment resulted in at least a 50% volume reduction to give mechanically robust spherical materials. Scanning electron microscope investigations of cross-sections of the beads combined with energy dispersive analysis showed that initially all elements were uniformly distributed through the resin matrix but that at higher temperatures the distribution of Cs became inhomogeneous. Although Cs was found in the entire cross-section, a significant proportion of the Cs occurred within internal rings while a proportion migrated toward the outer surfaces to form a crustal deposit. Leaching experiments conducted in water at 25 Degree-Sign C showed that the divalent contaminant elements were very difficult to leach from the beads heated in inert atmospheres in the range 200-600 Degree-Sign C. Cumulative fractional loses of the order of 0.001 were observed for these divalent elements for temperatures below 500 Degree-Sign C. Regardless of the processing temperature, the cumulative fractional loss of Cs in water at 25 Degree-Sign C reached a plateau or

  6. USE OF CATIONIC SURFACTANTS TO MODIFY SOIL SURFACES TO PROMOTE SORPTION AND RETARD MIGRATION OF HYDROPHOBIC ORGANIC COMPOUNDS

    Science.gov (United States)

    Cationic surfactants can be used to modify surfaces of soils and subsurface materials to promote adsorption of hydrophobic organic compounds (HOC). Batch and column experiments were performed to investigate this phenomenon with the cationic surfactant dodecylpyridinium (DP), a se...

  7. Pharmacology of the human red cell voltage-dependent cation channel Part I. Activation by clotrimazole and analogues

    DEFF Research Database (Denmark)

    Barksmann, Trine Lyberth; Kristensen, Berit I.; Christophersen, Palle.

    2004-01-01

    Human red cells, Nonselective voltage dependent cation channel, NSVDC channel, Gárdos channel blockers, NSVDC channel activators......Human red cells, Nonselective voltage dependent cation channel, NSVDC channel, Gárdos channel blockers, NSVDC channel activators...

  8. New methodology for a person identification system

    Indian Academy of Sciences (India)

    R Bremananth; A Chitra

    2006-06-01

    Reliable person identification is a key factor for any safety measure. Unlike other biometrics such as the palm, retina, gait, face and fingerprints, the characteristic of the iris is stable in a person’s lifetime. Iris patterns are chaotically distributed and well suited for recognizing persons throughout their lifetime with a single conscription. This paper proposes a new approach to person recognition based on iris patterns, which works with indoor outdoor conditions, spectacles contact lens wearing persons and diseased eyes. A challenge-response method is used for eye aliveness checking that puts off artificial sources from entering the iris database. The proposed algorithm can work with 84 statistical iris features that are extracted from an individual. Space and time complexity of the proposed approach is lesser than the existing methods. This algorithm has been implemented and results have been analysed on 2500 different iris patterns acquired in India under different real-time conditions. Experimental results illustrate that the proposed method has been easily espoused in elections, bank transactions and other security applications.

  9. Cationic antimicrobial peptides disrupt the Streptococcus pyogenes ExPortal.

    Science.gov (United States)

    Vega, Luis Alberto; Caparon, Michael G

    2012-09-01

    Although they possess a well-characterized ability to porate the bacterial membrane, emerging research suggests that cationic antimicrobial peptides (CAPs) can influence pathogen behaviour at levels that are sublethal. In this study, we investigated the interaction of polymyxin B and human neutrophil peptide (HNP-1) with the human pathogen Streptococcus pyogenes. At sublethal concentrations, these CAPs preferentially targeted the ExPortal, a unique microdomain of the S. pyogenes membrane, specialized for protein secretion and processing. A consequence of this interaction was the disruption of ExPortal organization and a redistribution of ExPortal components into the peripheral membrane. Redistribution was associated with inhibition of secretion of certain toxins, including the SpeB cysteine protease and the streptolysin O (SLO) cytolysin, but not SIC, a protein that protects S. pyogenes from CAPs. These data suggest a novel function for CAPs in targeting the ExPortal and interfering with secretion of factors required for infection and survival. This mechanism may prove valuable for the design of new types of antimicrobial agents to combat the emergence of antibiotic-resistant pathogens.

  10. Computer simulation of methanol exchange dynamics around cations and anions

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Santanu; Dang, Liem X.

    2016-03-03

    In this paper, we present the first computer simulation of methanol exchange dynamics between the first and second solvation shells around different cations and anions. After water, methanol is the most frequently used solvent for ions. Methanol has different structural and dynamical properties than water, so its ion solvation process is different. To this end, we performed molecular dynamics simulations using polarizable potential models to describe methanol-methanol and ion-methanol interactions. In particular, we computed methanol exchange rates by employing the transition state theory, the Impey-Madden-McDonald method, the reactive flux approach, and the Grote-Hynes theory. We observed that methanol exchange occurs at a nanosecond time scale for Na+ and at a picosecond time scale for other ions. We also observed a trend in which, for like charges, the exchange rate is slower for smaller ions because they are more strongly bound to methanol. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.

  11. Electromagnetic Properties of Substituted Ba - Ferrites by Selected Cations

    Directory of Open Access Journals (Sweden)

    Darina Kevicka

    2004-01-01

    Full Text Available The powdered samples of barium hexaferrite BaFe12-2x(Me1Me2 with x varying from 0.0 to 0.6 were prepared by citrate precursor method. The cation preference of mainly four-valence Me1=(Zr, Ti, Sn ions and two-valence Me2=(Co, Ni, Zn ions and their combinations in substituted Ba ferrites were investigated by the thermomagnetic analysis, Mossbauer spectroscopy and measurement of the magnetic properties. Mossbaur studies reveal that Zr4+, Sn4+ and less Co2+, Zn2+ ions have a strong preference to occupy 2b position, this position has the greatest contribution to the magnetocrystalline anisotropy. The La3+, Ti4+, Ni2+ ions preferently enter 4f2 sites and Zn2+, Co2+ ions also prefer to occupy 4f1 tetrahedral sites. The specific saturation magnetic polarisation Js-m and remanence Js-r increased with small x due to th substitution of non-magnetic and less magnetic ions in 4f1 and 4f2 sites. The coercivity Hc was casily controllable by the sustituions level x.

  12. An Overview on Metal Cations Extraction by Azocalixarenes

    Directory of Open Access Journals (Sweden)

    Hasalettin Deligöz

    2011-12-01

    Full Text Available In this overview, our main aim is to present the design, preparation, characterization, and extraction/sorption properties of chromogenic azocalix[4]arenes (substituted with different groups toward metal cations. Azocalixarenes, which contain a conjugated chromophore, i.e. azo (-N=N- group are synthesized in “one-pot” procedures in satisfactory yields. A wide variety of applications is expected by the functionalization of the side arms. Some of them are used to complex with metal ions. These macrocycles due to their bowl-shaped geometry are indeed used as hosts allowing ionic or organic guests to coordinate onto their cavity. The azocalixarene based ionophores are generally applied in various fields such as catalyst recovery, power plant, agriculture, metals finishing, microelectonics, biotechnology processes, rare earths speciation, and potable water purification. Besides these, they find applications in the area of selective ion extractions, receptors, optical devices, chemical sensor devices, the stationary phase for capillary chromatography, ion transport membranes, and luminescence probes etc. This survey is focused to provide overview an of the versatile nature of azocalix[n]arenes as highly efficient extractants for metal ions treated as pollutants.

  13. Transient receptor potential (TRP gene superfamily encoding cation channels

    Directory of Open Access Journals (Sweden)

    Pan Zan

    2011-01-01

    Full Text Available Abstract Transient receptor potential (TRP non-selective cation channels constitute a superfamily, which contains 28 different genes. In mammals, this superfamily is divided into six subfamilies based on differences in amino acid sequence homology between the different gene products. Proteins within a subfamily aggregate to form heteromeric or homomeric tetrameric configurations. These different groupings have very variable permeability ratios for calcium versus sodium ions. TRP expression is widely distributed in neuronal tissues, as well as a host of other tissues, including epithelial and endothelial cells. They are activated by environmental stresses that include tissue injury, changes in temperature, pH and osmolarity, as well as volatile chemicals, cytokines and plant compounds. Their activation induces, via intracellular calcium signalling, a host of responses, including stimulation of cell proliferation, migration, regulatory volume behaviour and the release of a host of cytokines. Their activation is greatly potentiated by phospholipase C (PLC activation mediated by coupled GTP-binding proteins and tyrosine receptors. In addition to their importance in maintaining tissue homeostasis, some of these responses may involve various underlying diseases. Given the wealth of literature describing the multiple roles of TRP in physiology in a very wide range of different mammalian tissues, this review limits itself to the literature describing the multiple roles of TRP channels in different ocular tissues. Accordingly, their importance to the corneal, trabecular meshwork, lens, ciliary muscle, retinal, microglial and retinal pigment epithelial physiology and pathology is reviewed.

  14. Biological removal of cationic fission products from nuclear wastewater.

    Science.gov (United States)

    Ngwenya, N; Chirwa, E M N

    2011-01-01

    Nuclear energy is becoming a preferred energy source amidst rising concerns over the impacts of fossil fuel based energy on global warming and climate change. However, the radioactive waste generated during nuclear power generation contains harmful long-lived fission products such as strontium (Sr). In this study, cationic strontium uptake from solution by microbial cultures obtained from mine wastewater is evaluated. A high strontium removal capacity (q(max)) with maximum loading of 444 mg/g biomass was achieved by a mixed sulphate reducing bacteria (SRB) culture. Sr removal in SRB was facilitated by cell surface based electrostatic interactions with the formation of weak ionic bonds, as 68% of the adsorbed Sr(2+) was easily desorbed from the biomass in an ion exchange reaction with MgCl₂. To a lesser extent, precipitation reactions were also found to account for the removal of Sr from aqueous solution as about 3% of the sorbed Sr was precipitated due to the presence of chemical ligands while the remainder occurred as an immobile fraction. Further analysis of the Sr-loaded SRB biomass by scanning electron microscopy (SEM) coupled to energy dispersive X-ray (EDX) confirmed extracellular Sr(2+) precipitation as a result of chemical interaction. In summary, the obtained results demonstrate the prospects of using biological technologies for the remediation of industrial wastewaters contaminated by fission products.

  15. Radical-cationic gaseous amino acids: a theoretical study.

    Science.gov (United States)

    Sutherland, Kailee N; Mineau, Philippe C; Orlova, Galina

    2007-08-16

    Three major forms of gaseous radical-cationic amino acids (RCAAs), keto (COOH), enolic (C(OH)OH), and zwitterionic (COO(-)), as well as their tautomers, are examined for aliphatic Ala(.+), Pro(.+), and Ser(.+), sulfur-containing Cys(.+), aromatic Trp(.+), Tyr(.+), and Phe(.+), and basic His(.+). The hybrid B3LYP exchange-correlation functional with various basis sets along with the highly correlated CCSD(T) method is used. For all RCAAs considered, the main stabilizing factor is spin delocalization; for His(.+), protonation of the basic side chain is equally important. Minor stabilizing factors are hydrogen bonding and 3e-2c interactions. An efficient spin delocalization along the N-C(alpha)-C(O-)O moiety occurs upon H-transfer from C(alpha) to the carboxylic group to yield the captodative enolic form, which is the lowest-energy isomer for Ala(.+), Pro(.+), Ser(.+), Cys(.+), Tyr(.+), and Phe(.+). This H-transfer occurs in a single step as a 1,3-shift through the sigma-system. For His(.+), the lowest-energy isomer is formed upon H-transfer from C(alpha) to the basic side chain, which results in a keto form, with spin delocalized along the N-C(alpha)-C=O fragment. Trp(.+) is the only RCAA that favors spin delocalization over an aromatic system given the low ionization energy of indole. The lowest-energy isomer of Trp(.+) is a keto form, with no H-transfer.

  16. Uv Photodissociation Spectroscopy of Temperature Controlled Hydrated Phenol Cluster Cation

    Science.gov (United States)

    Kurusu, Itaru; Yagi, Reona; Kasahara, Yasutoshi; Ishikawa, Haruki

    2016-06-01

    Owing to various developments of spectroscopic techniques, microscopic hydration structures of various clusters in the gas phase have been determined so far. The next step for further understanding of the microscopic hydration is to reveal the temperature effect, such as a fluctuation of the hydration structure. Thus, we have been carrying out photodissociation spectroscopy on the hydrated phenol cation clusters, [PhOH(H_2O)_n]^+, trapped in our temperature-variable ion trap. After the last symposium, we succeeded in improving our experimental condition and recorded the UV photodissociation spectra of [PhOH(H_2O)_5]^+ at the trap temperatures of 20, 50, and 100 K. We identified three groups of bands by their temperature dependence in the spectra. Based on the results of the DFT calculations, we estimated the temperature dependence of the relative populations among the isomers. As a results, the isomers were grouped into three groups having different motifs of the hydrogen-bond structures. Comparing the experimental with the theoretical results, we assigned the relation between the band carriers and the hydrogen-bond structure motifs. Details of the discussion will be presented in the paper. H. Ishikawa, T. Nakano, T. Eguchi, T. Shibukawa, K. Fuke, Chem. Phys. Lett. 514, 234 (2011) R. Yagi, Y. Kasahara, H. Ishikawa, WH12, the 70th International Symposium on Molecular Spectroscopy (2015)

  17. Efficient intravesical therapy of bladder cancer with cationic doxorubicin nanoassemblies

    Directory of Open Access Journals (Sweden)

    Jin X

    2016-09-01

    Full Text Available Xun Jin,1 Peilan Zhang,1 Li Luo,1 Hao Cheng,1 Yunzu Li,1 Ting Du,1 Bingwen Zou,2 Maling Gou1 1State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, People’s Republic of China; 2Department of Thoracic Oncology, Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, People’s Republic of China Abstract: Nanoparticles have promising applications in drug delivery for cancer therapy. Herein, we prepared cationic 1,2-dioleoyl-3-trimethylammonium propane/methoxypoly (ethyleneglycol (DPP nanoparticles to deliver doxorubicin (Dox for intravesical therapy of bladder cancer. The DPP micelles have a mean dynamic diameter of 18.65 nm and a mean zeta potential of +19.6 mV. The DPP micelles could prolong the residence of Dox in the bladder, enhance the penetration of Dox into the bladder wall, and improve cellular uptake of Dox. The encapsulation by DPP micelles significantly improved the anticancer effect of Dox against orthotopic bladder cancer in vivo. This work described a Dox-loaded DPP nanoparticle with potential applications in intravesical therapy of bladder cancer. Keywords: bladder cancer, drug delivery, nanoparticles, intravesical therapy

  18. Organic cation secretion by Cancer borealis urinary bladder

    Energy Technology Data Exchange (ETDEWEB)

    Miller, D.S.; Holliday, C.W.

    1987-01-01

    In the crab, Cancer borealis, initial clearance studies showed a potent renal excretory system for the model organic cation, tetraethylammonium (TEA). (/sup 14/C)-TEA clearance averaged 145 +/- 32 ml/day, which was 18 times the paired polyethylene glycol clearance. TEA uptake by slices of urinary bladder was concentrative, saturable, inhibitable by N/sup 1/-methylnicotinamide chloride, and dependent on glycolytic, but not oxidative, metabolism. When mounted in flux chambers, bladders exhibited a large net secretory flux. For 0.1 mM TEA, the ratio of secretory to reabsorptive fluxes was 65. Urinary bladders from another crab, Cancer irroratus, and a lobster, Homarus americanus, also exhibited net TEA secretion. In C. borealis bladder, secretory transport was concentrative, saturable, and nearly abolished by addition of 1 mM quinine to the serosol bath. Reabsorptive transport was not concentrative and was not reduced by luminal quinine. The data are consistent with a secretory pathway that is transcellular and mediated by carriers at both the serosal and luminal membranes.

  19. Rapid and quantitative quality control of microarrays using cationic nanoparticles.

    Science.gov (United States)

    Sun, Ye; Fan, Wenhua; McCann, Michael P; Golovlev, Val

    2009-02-15

    The fabrication quality of microarrays significantly influences the accuracy and reproducibility of microarray experiments. In this report, we present a simple and fast quality control (QC) method for spotted oligonucleotide and cDNA microarrays. It employs a nonspecific electrostatic interaction of colloidal gold nanoparticles with the chemical groups of DNA molecules and other biomolecules immobilized on the microarray surface that bear positive or negative charges. An inexpensive flatbed scanner is used to visualize and quantify the binding of cationic gold particles to the anionic DNA probes on the microarray surface. An image analysis software was designed to assess the various parameters of the array spots including spot intensity, shape and array homogeneity, calculate the overall array quality score, and save the detailed array quality report in an Excel file. The gold staining technique is fast and sensitive. It can be completed in 10 min and detect less than 1% of the probe amount commonly recommended for microarrays. Compared to the current microarray QC method that utilizes the hybridization of probes with short random sequence oligonucleotides labeled with fluorophore, our gold staining method requires less time for the analysis, reduces the reagent cost, and eliminates the need for the expensive laser scanner.

  20. Nonbonded interactions in membrane active cyclic biopolymers. IV - Cation dependence

    Science.gov (United States)

    Radhakrishnan, R.; Srinivasan, S.; Prasad, C. V.; Brinda, S. R.; Macelroy, R. D.; Sundaram, K.

    1980-01-01

    Interactions of valinomycin and form of its analogs in several conformations with the central ions Li(+), Na(+), K(+), Rb(+) and Cs(+) are investigated as part of a study of the specific preference of valinomycin for potassium and the mechanisms of carrier-mediated ion transport across membranes. Ion binding energies and conformational potential energies are calculated taking into account polarization energy formulas and repulsive energy between the central ion and the ligand atoms for conformations representing various stages in ion capture and release for each of the two ring chiralities of valinomycin and its analogs. Results allow the prediction of the chirality and conformation most likely to be observed for a given analog, and may be used to synthesize analogs with a desired rigidity or flexibility. The binding energies with the alkali metal cations are found to decrease with increasing ion size, and to be smaller than the corresponding ion hydration energies. It is pointed out that the observed potassium preference may be explainable in terms of differences between binding and hydration energies. Binding energies are also noted to depend on ligand conformation.

  1. Structure-conductivity studies in polymer electrolytes containing multivalent cations

    CERN Document Server

    Aziz, M

    1996-01-01

    force microscopy (AFM). DSC evidences helped to explain the texture of the iron samples during the drying process, and showed transitions between low melting, PEO and high melting spherulites, and VTPM is able to visualise the spherulites present in the samples. AFM has successfully imaged the as cast PEO sub 8 :FeBr sub 2 sample and the surface effect causing extra resistance in the impedance spectra could be seen. Conductivity studies were carried out using a.c. impedance spectra. Fe(ll) samples exhibit the typical semicircle-spike plot but the Fe(lll) samples displayed an extra semicircle before the spike reflecting a surface effect. This is also manifested in the Arrhenius plots of the same samples where a dip was shown at 100 deg C. From the conductivity studies on the iron systems it was found that for the dry samples the optimum conductivity was observed in PEO sub 8 :FeBr sub x irrespective of the valence state of the cation. For the air-cast samples the optimum conductivity composition depends on the...

  2. Transport of biguanides by human organic cation transporter OCT2.

    Science.gov (United States)

    Sogame, Yoshihisa; Kitamura, Atsushi; Yabuki, Masashi; Komuro, Setsuko; Takano, Mikihisa

    2013-06-01

    Biguanides have the severe side effect of lactic acidosis. Although both metformin and phenformin are biguanide derivatives, there is a difference in the frequency at which they induce lactic acidosis. However, the reasons for the difference are not clear. Metformin has been reported to be mainly excreted into urine by human organic cation transporter 2 (hOCT2). The present study was designed to investigate the renal transport of metformin and phenformin, focusing on hOCT2, using hOCT2-expressing oocytes. Both biguanides were found to be good substrates for hOCT2. However, phenformin exhibited a higher affinity and transport activity than metformin. The Km values for metformin and phenformin were 235 and 37.4 μM, with CL(int) (V(max)/K(m)) values of 71.9×10⁻³ μL/min per oocyte and 209×10⁻³ μL/min per oocyte, respectively. This is the first report that has compared the transport profiles of these biguanides in hOCT2-expressing oocytes. The results suggest that plasma concentration of phenformin in subjects carrying hOCT2 variant may be higher compared to reference subjects, as reported in metformin. In addition, the relationship between plasma concentration of these biguanides and blood lactate level as well as the possible reasons for the difference in the associated frequency of occurrence of lactic acidosis are discussed.

  3. Cationic PAMAM dendrimers as pore-blocking binary toxin inhibitors.

    Science.gov (United States)

    Förstner, Philip; Bayer, Fabienne; Kalu, Nnanya; Felsen, Susanne; Förtsch, Christina; Aloufi, Abrar; Ng, David Y W; Weil, Tanja; Nestorovich, Ekaterina M; Barth, Holger

    2014-07-14

    Dendrimers are unique highly branched macromolecules with numerous groundbreaking biomedical applications under development. Here we identified poly(amido amine) (PAMAM) dendrimers as novel blockers for the pore-forming B components of the binary anthrax toxin (PA63) and Clostridium botulinum C2 toxin (C2IIa). These pores are essential for delivery of the enzymatic A components of the internalized toxins from endosomes into the cytosol of target cells. We demonstrate that at low μM concentrations cationic PAMAM dendrimers block PA63 and C2IIa to inhibit channel-mediated transport of the A components, thereby protecting HeLa and Vero cells from intoxication. By channel reconstitution and high-resolution current recording, we show that the PAMAM dendrimers obstruct transmembrane PA63 and C2IIa pores in planar lipid bilayers at nM concentrations. These findings suggest a new potential role for the PAMAM dendrimers as effective polyvalent channel-blocking inhibitors, which can protect human target cells from intoxication with binary toxins from pathogenic bacteria.

  4. Nicotine activates the chemosensory cation channel TRPA1.

    Science.gov (United States)

    Talavera, Karel; Gees, Maarten; Karashima, Yuji; Meseguer, Víctor M; Vanoirbeek, Jeroen A J; Damann, Nils; Everaerts, Wouter; Benoit, Melissa; Janssens, Annelies; Vennekens, Rudi; Viana, Félix; Nemery, Benoit; Nilius, Bernd; Voets, Thomas

    2009-10-01

    Topical application of nicotine, as used in nicotine replacement therapies, causes irritation of the mucosa and skin. This reaction has been attributed to activation of nicotinic acetylcholine receptors (nAChRs) in chemosensory neurons. In contrast with this view, we found that the chemosensory cation channel transient receptor potential A1 (TRPA1) is crucially involved in nicotine-induced irritation. We found that micromolar concentrations of nicotine activated heterologously expressed mouse and human TRPA1. Nicotine acted in a membrane-delimited manner, stabilizing the open state(s) and destabilizing the closed state(s) of the channel. In the presence of the general nAChR blocker hexamethonium, nociceptive neurons showed nicotine-induced responses that were strongly reduced in TRPA1-deficient mice. Finally, TRPA1 mediated the mouse airway constriction reflex to nasal instillation of nicotine. The identification of TRPA1 as a nicotine target suggests that existing models of nicotine-induced irritation should be revised and may facilitate the development of smoking cessation therapies with less adverse effects.

  5. Effect of cation trapping on thermal stability of magnetite nanoparticles.

    Science.gov (United States)

    Pati, S S; Philip, John

    2014-06-01

    We investigate the effect of sodium trapping on thermal stability of magnetite (Fe3O4) nanoparticles. The pure magnetite nanoparticles incubated in sodium hydroxide solutions and subsequently washed with water to remove the excess sodium. The amount of sodium in magnetite is measured using atomic absorption spectroscopy. The size distribution obtained from Small angle X-ray scattering measurements show that particles are fairly monodisperse. The FTIR spectra of nanoparticles show transmission bands at 441 and 611 cm(-1) are due to the symmetric stretching vibrations (v) of Fe-O in octahedral and tetrahedral sites respectively. With 500 ppm of sodium ions (Na+) in magnetite, the cubic ferrite structure of maghemite (gamma-Fe2O3) to hexagonal hematite (alpha-Fe2O3) phase transition is enhanced by -150 degrees C in air. The Rietveld analysis of sodium doped magnetite nanoparticles show that above 99% of metastable gamma-Fe2O3 is converted to a thermodynamically stable alpha-Fe2O3 after air annealing at 700 degrees C. A decrease in enthalpy observed in doped magnetite unambiguously confirms that the activation energy for maghemite to hematite transition is increased due to the presence of trapped sodium ions. These results suggest that the trapped cations in ferrite nanoparticles can stabilize them by increasing the activation energy.

  6. Dipicolinate complexes of main group metals with hydrazinium cation

    Indian Academy of Sciences (India)

    K Saravanan; S Govindarajan

    2002-02-01

    Some new coordination complexes of hydrazinium main group metal dipicolinate hydrates of formulae (N2H5)2M(dip)2.H2O (where, M =Ca, Sr, Ba or Pb and = 0, 2, 4 and 3 respectively and dip = dipicolinate), N2H5Bi(dip)2.3H2O and (N2H5)3Bi(dip)3.4H2O have been prepared and characterized by physico-chemical techniques. The infrared spectra of the complexes reveal the presence of tridentate dipicolinate dianions and non-coordinating hydrazinium cations. Conductance measurements show that the mono, di and trihydrazinium complexes behave as 1:1, 2:1 and 3:1 electrolytes respectively, in aqueous solution. Thermal decomposition studies show that these compounds lose water followed by endothermic decomposition of hydrazine to give respective metal hydrogendipicolinate intermediates, which further decompose exothermically to the final product of either metal carbonates (Ca, Sr, Ba and Pb) or metal oxycarbonates (Bi). The coordination numbers around the metal ions differ from compound to compound. The various coordination numbers exhibited by these metals are six (Ca), seven (Ba), eight (Sr) and nine (Pb and Bi). In all the complexes the above coordination number is attained by tridentate dipicolinate dianions and water molecules. The X-ray diffraction patterns of these compounds differ from one another suggesting that they are not isomorphous.

  7. An FPGA implementation to detect selective cationic antibacterial peptides.

    Science.gov (United States)

    Polanco González, Carlos; Nuño Maganda, Marco Aurelio; Arias-Estrada, Miguel; del Rio, Gabriel

    2011-01-01

    Exhaustive prediction of physicochemical properties of peptide sequences is used in different areas of biological research. One example is the identification of selective cationic antibacterial peptides (SCAPs), which may be used in the treatment of different diseases. Due to the discrete nature of peptide sequences, the physicochemical properties calculation is considered a high-performance computing problem. A competitive solution for this class of problems is to embed algorithms into dedicated hardware. In the present work we present the adaptation, design and implementation of an algorithm for SCAPs prediction into a Field Programmable Gate Array (FPGA) platform. Four physicochemical properties codes useful in the identification of peptide sequences with potential selective antibacterial activity were implemented into an FPGA board. The speed-up gained in a single-copy implementation was up to 108 times compared with a single Intel processor cycle for cycle. The inherent scalability of our design allows for replication of this code into multiple FPGA cards and consequently improvements in speed are possible. Our results show the first embedded SCAPs prediction solution described and constitutes the grounds to efficiently perform the exhaustive analysis of the sequence-physicochemical properties relationship of peptides.

  8. Script identification in printed bilingual documents

    Indian Academy of Sciences (India)

    D Dhanya; A G Ramakrishnan; Peeta Basa Pati

    2002-02-01

    Identification of the script of the text in multi-script documents is one of the important steps in the design of an OCR system for the analysis and recognition of the page. Much work has already been reported in this area relating to Roman, Arabic, Chinese, Korean and Japanese scripts. In the Indian context, though some results have been reported, the task is still at its infancy. In the work presented in this paper, a successful attempt has been made to identify the script, at the word level, in a bilingual document containing Roman and Tamil scripts. Two different approaches have been proposed and thoroughly tested. In the first method, words are divided into three distinct spatial zones. The spatial spread of a word in upper and lower zones, together with the character density, is used to identify the script. The second technique analyses the directional energy distribution of a word using Gabor filters with suitable frequencies and orientations. Words with various font styles and sizes have been used for the testing of the proposed algorithms and the results are quite encouraging.

  9. Comprehensive study of tartrazine/cationic surfactant interaction.

    Science.gov (United States)

    Shahir, Afshin Asadzadeh; Javadian, Soheila; Razavizadeh, Bi Bi Marzieh; Gharibi, Hussein

    2011-12-15

    Interaction of a food dye, tartrazine, with some cationic conventional and gemini surfactants, tetradecyltrimethylammonium bromide (TTAB), N,N'-ditetradecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (14,4,14), and N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (12,4,12), were first investigated comprehensively employing conductometry, tensiometry, and UV-visible spectroscopy. Tartrazine was found to behave in the same manner as aromatic counterions. The formation of ion pairs reflected as a considerable increase of the surfactant efficiency in tensiometry plots and their stoichiometry were determined by Job's method of continuous variations. For the tartrazine/TTAB system, nonionic DS(3), ionic DS(2-), and/or DS(2)(-) ion pairs, their small premicelles, and tartrazine-rich micelles were constituted as well as dye-containing TTAB-rich micelles. Insoluble J-aggregates of DS(-) ion pairs and cylindrical surfactant-rich micelles were also formed in tartrazine/gemini surfactant systems and recognized by transmission electron microscopy. The zeta potential and the size of the aggregates were determined using dynamic light scattering and confirmed the suggested models for the processes happening in each system. Cyclic voltammetry was applied successfully to track all of these species using tartrazine's own reduction peak current for the first time.

  10. Closed-Shell Polycyclic Aromatic Hydrocarbon Cations: A New Category of Interstellar Polycyclic Aromatic Hydrocarbons

    Science.gov (United States)

    Hudgins, Douglas M.; Bauschlicher, Charles W., Jr.; Allamandola, Louis J.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Density functional theory has been employed to calculate the harmonic frequencies and intensities of a range of polycyclic aromatic hydrocarbon (PAH) cations that explore both size and electronic structure effects of the infrared spectroscopic properties of these species. The sample extends the size range of PAH species considered to more than 50 carbon atoms and includes several representatives from each of two heretofore unexplored categories of PAH cations: (1) fully benzenoid PAH cations whose carbon skeleton is composed of an odd number of carbon atoms (C(sub odd) PAHs); and (2) protonated PAH cations (HPAH+). Unlike the radical electronic structures of the PAH cations that have been the subject of previous theoretical and experimental work, the species in these two classes have a closed-shell electronic configuration. The calculated spectra of circumcoronene, C54H18 in both neutral and (radical) cationic form are also reported and compared with those of the other species. Overall, the C(sub odd) PAHs spectra are dominated by strong CC stretching modes near 1600 cm(exp -1) and display spectra that are remarkably insensitive to molecular size. The HPAH+ species evince a more complex spectrum consistent with the added contributions of aliphatic modes and their generally lower symmetry. Finally, for both classes of closed-shell cations, the intensity of the aromatic CH stretching modes is found to increase with molecular size far out of proportion with the number of CH groups, approaching a value more typical of neutral PAHs for the largest species studied.

  11. On the feasibility of designing hyperalkali cations using superalkali clusters as ligands

    Science.gov (United States)

    Sun, Wei-Ming; Li, Xiang-Hui; Li, Ying; Liu, Jia-Yuan; Wu, Di; Li, Chun-Yan; Ni, Bi-Lian; Li, Zhi-Ru

    2016-11-01

    The possibility of using superalkali clusters instead of alkali atoms as ligands to design a class of cationic compounds, referred to as hyperalkali cations, has been examined by using gradient-corrected density functional theory. By taking typical superalkalis (FLi2, OLi3, and NLi4) as examples, a series of hyperalkali cations ML2+ [M = (super)halogen; L = superalkali] have been constructed and investigated. Calculational results show that all the superalkali moieties preserve their geometric and electronic integrity in these proposed cations. The stability of these studied cations is guaranteed by the strong ionic bonds between superalkali ligand and (super)halogen core, as well as their large highest occupied molecular orbital-lowest unoccupied molecular orbital gaps and positive dissociation energies. In particular, all these proposed cations possess lower vertical electron affinities (2.36-3.56 eV) than those of their corresponding cationic superalkali ligands, verifying their hyperalkali nature. We, therefore, hope that this study will provide an approach to obtain new species with excellent reducing capability by utilizing various superalkalis as building blocks.

  12. A novel Ag+ cation sensor based on polyamidoamine dendrimer modified with 1,8-naphthalimide derivatives

    Science.gov (United States)

    Dodangeh, Mohammad; Gharanjig, Kamaladin; Arami, Mokhtar

    2016-02-01

    In this study, 4-amino-1,8-naphthalimide-conjugated polyamidoamine dendrimer was synthesized and characterized and its potentiality as a cation sensor was investigated. 4-Amino-1,8-naphthalic anhydride reacted with polyamidoamine dendrimer and the product was characterized using FTIR, 1H NMR, 13C NMR and melting point analysis method. The synthesized compound was applied to detect various cations in water media and N,N-dimethylformamide (DMF) via monitoring the quenching of the fluorescence intensity. Furthermore, various metal cations including Cu2 +, Ni2 +, Zn2 +, Pb2 +,Ca2 +, Ba2 +, Cd2 +, Hg2 +, Fe2 +, Fe3 + and Ag+ were tested. The complexes formed between the synthesized compound and metal cations in solution and their effects on Photoinduced Electron Transfer (PET) process were investigated regarding the potential application of the newly-synthesized dendrimer as a colorimetric and fluorescent sensor for such cations. The results clearly confirmed that the 1,8-naphthalimide groups surrounding the central dendrimer core showed strong green fluorescence emission at 553 nm. This effect considerably decreased with the introduction of all cations, except Ag+ where the fluorescence quenching effect was remarkable and more dominant. Therefore, it can be concluded that the synthesized dye has the potentiality of being a highly sensitive and selective fluorescence sensor for Ag+ cation.

  13. Competition between kaolinite flocculation and stabilization in divalent cation solutions dosed with anionic polyacrylamides.

    Science.gov (United States)

    Lee, Byung Joon; Schlautman, Mark A; Toorman, Erik; Fettweis, Michael

    2012-11-01

    Divalent cations have been reported to develop bridges between anionic polyelectrolytes and negatively-charged colloidal particles, thereby enhancing particle flocculation. However, results from this study of kaolinite suspensions dosed with various anionic polyacrylamides (PAMs) reveal that Ca(2+) and Mg(2+) can lead to colloid stabilization under some conditions. To explain the opposite but coexisting processes of flocculation and stabilization with divalent cations, a conceptual flocculation model with (1) particle-binding divalent cationic bridges between PAM molecules and kaolinite particles and (2) polymer-binding divalent cationic bridges between PAM molecules is proposed. The particle-binding bridges enhanced flocculation and aggregated kaolinite particles in large, easily-settleable flocs whereas the polymer-binding bridges increased steric stabilization by developing polymer layers covering the kaolinite surface. Both the particle-binding and polymer-binding divalent cationic bridges coexist in anionic PAM- and kaolinite-containing suspensions and thus induce the counteracting processes of particle flocculation and stabilization. Therefore, anionic polyelectrolytes in divalent cation-enriched aqueous solutions can sometimes lead to the stabilization of colloidal particles due to the polymer-binding divalent cationic bridges.

  14. Cationic cellulose nanofibers from waste pulp residues and their nitrate, fluoride, sulphate and phosphate adsorption properties.

    Science.gov (United States)

    Sehaqui, Houssine; Mautner, Andreas; Perez de Larraya, Uxua; Pfenninger, Numa; Tingaut, Philippe; Zimmermann, Tanja

    2016-01-01

    Cationic cellulose nanofibers (CNF) having 3 different contents of positively charged quaternary ammonium groups have been prepared from waste pulp residues according to a water-based modification method involving first the etherification of the pulp with glycidyltrimethylammonium chloride followed by mechanical disintegration. The cationic nanofibers obtained were observed by scanning electron microscopy and the extent of the reaction was evaluated by conductometric titration, ζ-potential measurements, and thermogravimetric analyses. The cationic CNF had a maximum cationic charge content of 1.2mmolg(-1) and positive ζ-potential at various pH values. Sorption of negatively charged contaminants (fluoride, nitrate, phosphate and sulphate ions) and their selectivity onto cationic CNF have been evaluated. Maximum sorption of ∼0.6mmolg(-1) of these ions by CNF was achieved and selectivity adsorption studies showed that cationic CNF are more selective toward multivalent ions (PO4(3-) and SO4(2-)) than monovalent ions (F(-) and NO3(-)). In addition, we demonstrated that cationic CNF can be manufactured into permeable membranes capable of dynamic nitrate adsorption by utilizing a simple paper-making process.

  15. Poorly selective cation channels in the apical membrane of A6 cells.

    Science.gov (United States)

    Van Driessche, W; De Smet, P; de Smedt, H

    1994-03-01

    This paper describes a Ca(2+)-blockable, poorly selective cation pathway in the apical membrane of A6 epithelia. This pathway has properties that resemble the cation-selective channels in the toad urinary bladder and frog skin. Transepithelial short circuit currents (Isc) and power density spectra (PDS) of the fluctuations in current were recorded. The basolateral surface of the tissues was exposed to Cl- or SO4(2-) solutions with Na+ as the major cation. Ca(2+)-blockable inward oriented currents and Lorentzian noise were recorded with isotonic (215 mosmol/kg) mucosal Cl- and hypotonic (144 mos-mol/kg serosal SO4(2-) solution with Na+, K+, Rb+ or Cs+ as the major mucosal cation. Experiments with mucosal K+ demonstrated that the cation-selective channel was markedly activated by serosal hypotonicity. Effects of an increased electrical driving force were excluded on the basis of the results obtained with microelectrode experiments and transepithelial voltage clamping. Cell volume expansion induced by isotonic replacements of serosal sucrose by glycerol or urea also activated the cation-selective pathway. Furthermore, the presence of Cl- in the mucosal solution was a prerequisite for a sustained response to hypotonicity or replacements of the organic compounds. Moreover, we found that the cation-selective channels are mainly expressed in the cells during the early period of epithelial growth.

  16. Theoretical study of the influence of cation vacancies on the catalytic properties of vanadium antimonate

    Energy Technology Data Exchange (ETDEWEB)

    Messina, S. [Laboratorio de Procesos Cataliticos, Departamento de Ingenieria Quimica, FIUBA, Pabellon de Industrias, Ciudad Universitaria, (1428) Capital Federal (Argentina); Juan, A. [Departamento de Fisica, UNS, Av. Alem 1253, (8000) Bahia Blanca (Argentina)], E-mail: cajuan@uns.edu.ar; Larrondo, S.; Irigoyen, B.; Amadeo, N. [Laboratorio de Procesos Cataliticos, Departamento de Ingenieria Quimica, FIUBA, Pabellon de Industrias, Ciudad Universitaria, (1428) Capital Federal (Argentina)

    2008-07-15

    We have theoretically studied the influence of antimony and vanadium cation vacancies in the electronic structure and reactivity of vanadium antimonate, using molecular orbital methods. From the analysis of the electronic properties of the VSbO{sub 4} crystal structure, we can infer that both antimony and vanadium vacancies increase the oxidation state of closer V cations. This would indicate that, in the rutile-type VSbO{sub 4} phase the Sb and V cations defects stabilize the V in a higher oxidation state (V{sup 4+}). Calculations of the adsorption energy for different toluene adsorption geometries on the VSbO{sub 4}(1 1 0) surface have also been performed. The oxidation state of Sb, V and O atoms and the overlap population of metal-oxygen bonds have been evaluated. Our results indicate that the cation defects influence in the toluene adsorption reactions is slight. We have computed different alternatives for the reoxidation of the VSbO{sub 4}(1 1 0) surface active sites which were reduced during the oxygenated products formation. These calculations indicate that the V cations in higher oxidation state (V{sup 4+}) are the species, which preferentially incorporate lattice oxygen to the reduced Sb cations. Thus, the cation defects would stabilize the V{sup 4+} species in the VSbO{sub 4} structure, determining its ability to provide lattice oxygen as a reactant.

  17. Molecular modeling of organic corrosion inhibitors: why bare metal cations are not appropriate models of oxidized metal surfaces and solvated metal cations.

    Science.gov (United States)

    Kokalj, Anton

    2014-01-01

    The applicability of various models of oxidized metal surfaces - bare metal cations, clusters of various size, and extended (periodic) slabs - that are used in the field of quantum-chemical modeling of corrosion inhibitors is examined and discussed. As representative model systems imidazole inhibitor, MgO surface, and solvated Mg(2+) ion are considered by means of density-functional-theory calculations. Although the results of cluster models are prone to cluster size and shape effects, the clusters of moderate size seem useful at least for qualitative purposes. In contrast, the bare metal cations are useless not only as models of oxidized surfaces but also as models of solvated cations, because they bind molecules several times stronger than the more appropriate models. In particular, bare Mg(2+) binds imidazole by 5.9 eV, while the slab model of MgO(001) by only 0.35 eV. Such binding is even stronger for 3+ cations, e.g., bare Al(3+) binds imidazole by 17.9 eV. The reasons for these fantastically strong binding energies are discussed and it is shown that the strong bonding is predominantly due to electron charge transfer from molecule to metal cation, which stems from differences between molecular and metal ionization potentials.

  18. Reactions of atomic cations with methane: gas phase room-temperature kinetics and periodicities in reactivity.

    Science.gov (United States)

    Shayesteh, Alireza; Lavrov, Vitali V; Koyanagi, Gregory K; Bohme, Diethard K

    2009-05-14

    Reactions of methane have been measured with 59 atomic metal cations at room temperature in helium bath gas at 0.35 Torr using an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. The atomic cations were produced at approximately 5500 K in an ICP source and allowed to decay radiatively and to thermalize by collisions with argon and helium atoms prior to reaction. Rate coefficients and product distributions are reported for the reactions of fourth-row atomic cations from K(+) to Se(+), of fifth-row atomic cations from Rb(+) to Te(+) (excluding Tc(+)), of sixth-row atomic cations from Cs(+) to Bi(+), and of the lanthanide cations from La(+) to Lu(+) (excluding Pm(+)). Two primary reaction channels were observed: C-H bond insertion with elimination of H(2), and CH(4) addition. The bimolecular H(2) elimination was observed in the reactions of CH(4) with As(+), Nb(+), and some sixth-row metal cations, i.e., Ta(+), W(+), Os(+), Ir(+), Pt(+); secondary and higher-order H(2) elimination was observed exclusively for Ta(+), W(+), and Ir(+) ions. All other transition-metal cations except Mn(+) and Re(+) were observed to react with CH(4) exclusively by addition, and up to two methane molecules were observed to add sequentially to most transition-metal ions. CH(4) addition was also observed for Ge(+), Se(+), La(+), Ce(+), and Gd(+) ions, while the other main-group and lanthanide cations did not react measurably with methane.

  19. Optimizing delivery systems for cationic biopolymers: competitive interactions of cationic polylysine with anionic κ-carrageenan and pectin.

    Science.gov (United States)

    Lopez-Pena, Cynthia Lyliam; McClements, David Julian

    2014-06-15

    Polylysine is a cationic biopolymer with a strong antimicrobial activity against a wide range of microorganisms, however, its functional performance is influenced by its interactions with anionic biopolymers. We examined the stability of polylysine-pectin complexes in the presence of carrageenan, and vice versa. Polylysine-pectin or polylysine-carrageenan complexes were formed at mass ratios of 1:0 to 1:32 (pH 3.5), and then micro-electrophoresis, turbidity, microscopy, and isothermal titration calorimetry (ITC) were used to characterise them. Solutions containing polylysine-pectin complexes were slightly turbid and relatively stable to aggregation at high mass ratios, whereas those containing polylysine-carrageenan complexes were turbid and unstable to aggregation and precipitation. Pectin did not strongly interact with polylysine-carrageenan complexes, whereas carrageenan displaced pectin from polylysine-pectin complexes, which was attributed to differences in electrostatic attraction between polylysine, carrageenan, and pectin. These results have important implications for the design of effective antimicrobial delivery systems for foods and beverages.

  20. In vitro delivery of curcumin with cholesterol-based cationic liposomes.

    Science.gov (United States)

    Apiratikul, N; Penglong, T; Suksen, K; Svasti, S; Chairoungdua, A; Yingyongnarongkula, B

    2013-01-01

    A new cholesterol-based cationic lipid was synthesized; liposomes prepared on its basis were evaluated as drug delivery vehicles for curcumin. Free and liposome-encapsulated curcumin cytotoxicity against HeLa, A549, HepG2, K562 and 1301 cell lines was assessed. Liposomal curcumin with ED50 values ranging from 2.5-10 microM exhibited 2-8 times higher cytotoxicity than free curcumin. The synthetic cholesterol-based cationic lipid also enhanced cellular uptake of curcumin into tested cells. Cationic liposome alone showed low cytotoxicity at high doses with ED50 values of 90-210 microM.

  1. Aftertreatment of Conventional Direct Dyeings of Cotton with a Bis-reactive Cationic Fixing Agent

    Institute of Scientific and Technical Information of China (English)

    SHARIF Saima; SAEED Ahmad; MUHAMMAD Naeem Khan; MUHAMMAD Fauz-uI-Azeem

    2009-01-01

    A his-reactive cationic fixing agent,ethylenebis[N-(2,3-epoxypropyl)-N,N-dimethylammonium chloride] has been used as an aftertreatment reagent to improve the wash fasmess of direct dyes on cotton.The effects of different pH conditions and concentrations on the effectiveness of this cationic fixing agent have been investigated.The results showed that aftertreatment at pH 11 produced dyeings with higher colour strength and better wash fastness than that at pH 7.In addition,the cationic agent at a low concentration was found to be more effective under both neutral and alkaline conditions.

  2. Arginine-based cationic liposomes for efficient in vitro plasmid DNA delivery with low cytotoxicity

    Directory of Open Access Journals (Sweden)

    Sarker SR

    2013-04-01

    Full Text Available Satya Ranjan Sarker, Yumiko Aoshima, Ryosuke Hokama, Takafumi Inoue, Keitaro Sou, Shinji Takeoka Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University (TWIns, Tokyo, Japan Background: Currently available gene delivery vehicles have many limitations such as low gene delivery efficiency and high cytotoxicity. To overcome these drawbacks, we designed and synthesized two cationic lipids comprised of n-tetradecyl alcohol as the hydrophobic moiety, 3-hydrocarbon chain as the spacer, and different counterions (eg, hydrogen chloride [HCl] salt or trifluoroacetic acid [TFA] salt in the arginine head group. Methods: Cationic lipids were hydrated in 4-(2-hydroxyethyl-1-piperazineethanesulfonic acid (HEPES buffer to prepare cationic liposomes and characterized in terms of their size, zeta potential, phase transition temperature, and morphology. Lipoplexes were then prepared and characterized in terms of their size and zeta potential in the absence or presence of serum. The morphology of the lipoplexes was determined using transmission electron microscopy and atomic force microscopy. The gene delivery efficiency was evaluated in neuronal cells and HeLa cells and compared with that of lysine-based cationic assemblies and Lipofectamine™ 2000. The cytotoxicity level of the cationic lipids was investigated and compared with that of Lipofectamine™ 2000. Results: We synthesized arginine-based cationic lipids having different counterions (ie, HCl-salt or TFA-salt that formed cationic liposomes of around 100 nm in size. In the absence of serum, lipoplexes prepared from the arginine-based cationic liposomes and plasmid (p DNA formed large aggregates and attained a positive zeta potential. However, in the presence of serum, the lipoplexes were smaller in size and negative in zeta potential. The morphology of the lipoplexes was vesicular. Arginine-based cationic liposomes with HCl-salt showed the

  3. Reactions of the radical cations of methylated benzene derivatives in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Sehested, K.; Holcman, J.

    1978-03-23

    The radical cations of methylated benzene decompose in acid solution into the corresponding methylbenzyl radical and a proton. The rate constant for this reaction decreases by three orders of magnitude as the number of methyl groups increases from one to five. The rate constants can be correlated with the ionization potential of the parent compound. In neutral solution the reverse reaction to the acid-catalyzed OH adduct conversion occurs and the radical cations react with water to form the OH adduct. In slightly alkaline solution the radical cations of the higher methylated benzenes (n greater than or equal to 3) react with hydroxide ions forming the OH adduct.

  4. Full automation of {sup 68}Ga labelling of DOTA-peptides including cation exchange prepurification

    Energy Technology Data Exchange (ETDEWEB)

    Ocak, M. [Clinical Department of Nuclear Medicine, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Department of Pharmaceutical Technology, Pharmacy Faculty, Istanbul University, Istanbul (Turkey); Antretter, M. [Clinical Department of Nuclear Medicine, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Knopp, R.; Kunkel, F. [Eckert and Ziegler Eurotope GmbH, Berlin (Germany); Petrik, M. [Clinical Department of Nuclear Medicine, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Bergisadi, N. [Department of Pharmaceutical Technology, Pharmacy Faculty, Istanbul University, Istanbul (Turkey); Decristoforo, C. [Clinical Department of Nuclear Medicine, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria)], E-mail: Clemens.Decristoforo@uki.at

    2010-02-15

    Here we describe a fully automated approach for the synthesis of {sup 68}Ga-labelled DOTA-peptides based on pre-concentration and purification of the generator eluate by using a cation exchange-cartridge and its comparison with fully automated direct labelling applying fractionated elution. Pre-concentration of the eluate on a cation exchange cartridge both using a resin-based and a disposable cation-exchange cartridge efficiently removed {sup 68}Ge as well as major metal contaminations with Fe and Zn. This resulted in a high labelling efficiency of DOTA-peptides at high specific activity (SA) with short synthesis times.

  5. Determining the cation exchange capacity of montmorillonite by simultaneous thermal analysis method

    Science.gov (United States)

    Boeva, N. M.; Bocharnikova, Yu. I.; Belousov, P. E.; Zhigarev, V. V.

    2016-08-01

    A way of determining the cation exchange capacity of montmorillonite by simultaneous thermal analysis is developed using as an example the bentonites of the 10th Khutor deposit (Republic of Khakassia) and the Vodopadnyi area (Sakhalin Island). A correlation is established between the cation exchange capacity of smectite and its weight loss upon heating in the range of dehydration; the enthalpy of dehydration of montmorillonite; and the weight loss and the enthalpy of thermal dissociation of ethylene glycol contained in the interlayer space of the mineral's crystal structure. These data open up new possibilities for determining the cation exchange capacity of montmorillonite, the most important technological indicator of the natural clay nanomineral.

  6. The quantitative relationship between metal radii, cationic radii and electronic configurations of elements

    Institute of Scientific and Technical Information of China (English)

    艾德生; 曾荣树; 叶大年

    1999-01-01

    A close relationship has been found between the metal radii, cationic radii and electronic configurations of elements. A unified formula for calculating metal radii is presented, whose paramatem are only related to the electronic configuration. Meanwhile theoretical relation between cationic radii and electronic configuration can be revealed by combining quantitative analysis with qualitative analysis. The calculated results and the charts of standard deviations are coincident with those given by reference books. Our work indicates that the metal radius and cationic radius of an element reflect in essence the element’s configuration.

  7. Golden gate shuffling: a one-pot DNA shuffling method based on type IIs restriction enzymes.

    Directory of Open Access Journals (Sweden)

    Carola Engler

    Full Text Available We have developed a protocol to assemble in one step and one tube at least nine separate DNA fragments together into an acceptor vector, with 90% of recombinant clones obtained containing the desired construct. This protocol is based on the use of type IIs restriction enzymes and is performed by simply subjecting a mix of 10 undigested input plasmids (nine insert plasmids and the acceptor vector to a restriction-ligation and transforming the resulting mix in competent cells. The efficiency of this protocol allows generating libraries of recombinant genes by combining in one reaction several fragment sets prepared from different parental templates. As an example, we have applied this strategy for shuffling of trypsinogen from three parental templates (bovine cationic trypsinogen, bovine anionic trypsinogen and human cationic trypsinogen each divided in 9 separate modules. We show that one round of shuffling using the 27 trypsinogen entry plasmids can easily produce the 19,683 different possible combinations in one single restriction-ligation and that expression screening of a subset of the library allows identification of variants that can lead to higher expression levels of trypsin activity. This protocol, that we call 'Golden Gate shuffling', is robust, simple and efficient, can be performed with templates that have no homology, and can be combined with other shuffling protocols in order to introduce any variation in any part of a given gene.

  8. Antimicrobial sand via adsorption of cationic Moringa oleifera protein.

    Science.gov (United States)

    Jerri, Huda A; Adolfsen, Kristin J; McCullough, Lauren R; Velegol, Darrell; Velegol, Stephanie B

    2012-01-31

    Moringa oleifera (Moringa) seeds contain a natural cationic protein (MOCP) that can be used as an antimicrobial flocculant for water clarification. Currently, the main barrier to using Moringa seeds for producing potable water is that the seeds release other water-soluble proteins and organic matter, which increase the concentration of dissolved organic matter (DOM) in the water. The presence of this DOM supports the regrowth of pathogens in treated water, preventing its storage and later use. A new strategy has been established for retaining the MOCP protein and its ability to clarify and disinfect water while removing the excess organic matter. The MOCP is first adsorbed and immobilized onto sand granules, followed by a rinsing step wherein the excess organic matter is removed, thereby preventing later growth of bacteria in the purified water. Our hypotheses are that the protein remains adsorbed onto the sand after the functionalization treatment, and that the ability of the antimicrobial functionalized sand (f-sand) to clarify turbidity and kill bacteria, as MOCP does in bulk solution, is maintained. The data support these hypotheses, indicating that the f-sand removes silica microspheres and pathogens from water, renders adhered Escherichia coli bacteria nonviable, and reduces turbidity of a kaolin suspension. The antimicrobial properties of f-sand were assessed using fluorescent (live-dead) staining of bacteria on the surface of the f-sand. The DOM that can contribute to bacterial regrowth was shown to be significantly reduced in solution, by measuring biochemical oxygen demand (BOD). Overall, these results open the possibility that immobilization of the MOCP protein onto sand can provide a simple, locally sustainable process for producing storable drinking water.

  9. Thermodynamics of cationic surfactant sorption onto natural clinoptilolite

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, E.J.; Bowman, R.S. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States); Carey, J.W. [Los Alamos National Lab., NM (United States)

    1998-10-15

    Sorption enthalpies of hexadecyltrimethylammonium bromide (HDTMA) as monomers and micelles and tetraethylammonium bromide (TEA) were used with surfactant, counterion, and co-ion sorption isotherms to infer the conformation, sorption mechanism, and relative stability of the sorbed surfactants on natural clinoptilolite. The average value of the sorption enthalpy was {minus}10.38 kJ/mol for monomers, {minus}11.98 kJ/mol for micelles, and +3.03 kJ/mol for TEA. Sorption of monomers produced a lower sorption plateau than equivalent micelle sorption (maxima 145 mmol/kg, 225 mmol/kg). Analysis of the sorption data demonstrated a change in the sorption mechanism at the external cation exchange capacity (ECEC) of clinoptilolite. Sorption data from below and above the ECEC were fit to a simple polynomial model and the Gibbs free energy of sorption ({Delta} G{sub m}{sup 0}) and sorption entropies were calculated. Resultant values of {Delta} G{sub m}{sup 0} were {minus}9.27 and {minus}14.38 kJ/mol for HDTMA monomers and micelles, respectively, for sorption below the ECEC, and {minus}16.11 and {minus}23.10 kJ/mol, respectively, for sorption above the ECEC. The value for TEA was {minus}1.04 kJ/mol, indicating weaker sorption than for HDTMA. Monomer sorption to clinoptilolite exceeded the ECEC, even when the solution concentration was below the critical micelle concentration. Hydrophobic (tail-tail) components of {Delta} G{sub m}{sup 0} were the driving force for sorption of HDTMA, both below and above the ECEC. A significant kinetic effect was observed in the sorption isotherms with a period of rapid sorption followed by slow equilibration requiring 7 days to achieve steady state for HDTMA; TEA equilibration occurred within 24 h.

  10. Riparian zone controls on base cation concentrations in boreal streams

    Directory of Open Access Journals (Sweden)

    J. L. J. Ledesma

    2013-01-01

    Full Text Available Forest riparian zones are a major in control of surface water quality. Base cation (BC concentrations, fluxes, and cycling in the riparian zone merit attention because of increasing concern of negative consequences for re-acidification of surface waters from future climate and forest harvesting scenarios. We present a two-year study of BC and silica (Si flow-weighted concentrations from 13 riparian zones and 14 streams in a boreal catchment in northern Sweden. The Riparian Flow-Concentration Integration Model (RIM was used to estimate riparian zone flow-weighted concentrations and tested to predict the stream flow-weighted concentrations. Spatial variation in BC and Si concentrations as well as in flow-weighted concentrations was related to differences in Quaternary deposits, with the largest contribution from lower lying silty sediments and the lowest contribution from wetland areas higher up in the catchment. Temporal stability in the concentrations of most elements, a remarkably stable Mg / Ca ratio in the soil water and a homogeneous mineralogy suggest that the stable patterns found in the riparian zones are a result of distinct mineralogical upslope groundwater signals integrating the chemical signals of biological and chemical weathering. Stream water Mg / Ca ratio indicates that the signal is subsequently maintained in the streams. RIM gave good predictions of Ca, Mg, and Na flow-weighted concentrations in headwater streams. The difficulty in modelling K and Si suggests a stronger biogeochemical influence on these elements. The observed chemical dilution effect with flow in the streams was related to variation in groundwater levels and element concentration profiles in the riparian zones. This study provides a first step toward specific investigations of the vulnerability of riparian zones to changes induced by forest management or climate change, with focus on BC or other compounds.

  11. Riparian zone control on base cation concentration in boreal streams

    Directory of Open Access Journals (Sweden)

    J. L. J. Ledesma

    2013-06-01

    Full Text Available Riparian zones (RZ are a major factor controlling water chemistry in forest streams. Base cations' (BC concentrations, fluxes, and cycling in the RZ merit attention because a changing climate and increased forest harvesting could have negative consequences, including re-acidification, for boreal surface waters. We present a two-year study of BC and silica (Si flow-weighted concentrations from 13 RZ and 14 streams in different landscape elements of a boreal catchment in northern Sweden. The spatial variation in BC and Si dynamics in both RZ and streams was explained by differences in landscape element type, with highest concentrations in silty sediments and lowest concentrations in peat-dominated wetland areas. Temporal stability in BC and Si concentrations in riparian soil water, remarkably stable Mg/Ca ratios, and homogeneous mineralogy suggest that patterns found in the RZ are a result of a distinct mineralogical upslope signal in groundwater. Stream water Mg/Ca ratios indicate that the signal is subsequently maintained in the streams. Flow-weighted concentrations of Ca, Mg, and Na in headwater streams were represented by the corresponding concentrations in the RZ, which were estimated using the Riparian Flow-Concentration Integration Model (RIM approach. Stream and RZ flow-weighted concentrations differed for K and Si, suggesting a stronger biogeochemical influence on these elements, including K recirculation by vegetation and retention of Si within the RZ. Potential increases in groundwater levels linked to forest harvesting or changes in precipitation regimes would tend to reduce BC concentrations from RZ to streams, potentially leading to episodic acidification.

  12. Characterization and performance of short cationic antimicrobial peptide isomers.

    Science.gov (United States)

    Juba, Melanie; Porter, Devin; Dean, Scott; Gillmor, Susan; Bishop, Barney

    2013-07-01

    Cationic antimicrobial peptides (CAMPs) represent an ancient defense mechanism against invading bacteria, with peptides such as the cathelicidins being essential elements of vertebrate innate immunity. CAMPs are typically associated with broad-spectrum antimicrobial potency and limited bacterial resistance. The cathelicidin identified from the elapid snake Naja atra (NA-CATH) contains a semi-conserved repeated 11-residue motif (ATRA motif) with a sequence pattern consistent with formation of an amphipathic helical conformation. Short peptide amides (ATRA-1, -1A, -1P, and -2) generated based on the pair of ATRA motifs in NA-CATH exhibited varied antimicrobial potencies. The small size of the ATRA peptides, coupled with their varied antimicrobial performances, make them interesting models to study the impact various physico-chemical properties have on antimicrobial performance in helical CAMPs. Accordingly, the D- and L-enantiomers of the peptide ATRA-1A, which in earlier studies had shown both good antimicrobial performance and strong helical character, were investigated in order to assess the impact peptide stereochemistry has on antimicrobial performance and interaction with chiral membranes. The ATRA-1A isomers exhibit varied potencies against four bacterial strains, and their conformational properties in the presence of mixed zwitterionic/anionic liposomes are influenced by anionic lipid content. These studies reveal subtle differences in the properties of the peptide isomers. Differences are also seen in the abilities of the ATRA-1A isomers to induce liposome fusion/aggregation, bilayer rearrangement and lysing through turbidity studies and fluorescence microscopy. The similarities and differences in the properties of the ATRA-1A isomers could aid in efforts to develop D-peptide-based therapeutics using high-performing L-peptides as templates.

  13. The non-selective voltage-activated cation channel in the human red blood cell membrane: reconciliation between two conflicting reports and further characterisation

    DEFF Research Database (Denmark)

    Kaestner, Lars; Christophersen, Palle; Bernhardt, Ingolf;

    2000-01-01

    Erythrocyte; Patch-clamp; Non-specific; cation channel; Voltage dependence; Acetylcholin receptor......Erythrocyte; Patch-clamp; Non-specific; cation channel; Voltage dependence; Acetylcholin receptor...

  14. Selective trans-membrane transport of alkali and alkaline earth cations through graphene oxide membranes based on cation-π interactions.

    Science.gov (United States)

    Sun, Pengzhan; Zheng, Feng; Zhu, Miao; Song, Zhigong; Wang, Kunlin; Zhong, Minlin; Wu, Dehai; Little, Reginald B; Xu, Zhiping; Zhu, Hongwei

    2014-01-28

    Graphene and graphene oxide (G-O) have been demonstrated to be excellent filters for various gases and liquids, showing potential applications in areas such as molecular sieving and water desalination. In this paper, the selective trans-membrane transport properties of alkali and alkaline earth cations through a membrane composed of stacked and overlapped G-O sheets ("G-O membrane") are investigated. The thermodynamics of the ion transport process reveal that the competition between the generated thermal motions and the interactions of cations with the G-O sheets results in the different penetration behaviors to temperature variations for the considered cations (K(+), Mg(2+), Ca(2+), and Ba(2+)). The interactions between the studied metal atoms and graphene are quantified by first-principles calculations based on the plane-wave-basis-set density functional theory (DFT) approach. The mechanism of the selective ion trans-membrane transportation is discussed further and found to be consistent with the concept of cation-π interactions involved in biological systems. The balance between cation-π interactions of the cations considered with the sp(2) clusters of G-O membranes and the desolvation effect of the ions is responsible for the selectivity of G-O membranes toward the penetration of different ions. These results help us better understand the ion transport process through G-O membranes, from which the possibility of modeling the ion transport behavior of cellular membrane using G-O can be discussed further. The selectivity toward different ions also makes G-O membrane a promising candidate in areas of membrane separations.

  15. On the real performance of cation exchange resins in wastewater treatment under conditions of cation competition: the case of heavy metal pollution.

    Science.gov (United States)

    Prelot, Benedicte; Ayed, Imen; Marchandeau, Franck; Zajac, Jerzy

    2014-01-01

    Sorption performance of cation-exchange resins Amberlite® IRN77 and Amberlite™ IRN9652 toward Cs(I) and Sr(II) has been tested in single-component aqueous solutions and simulated waste effluents containing other monovalent (Effluent 1) or divalent (Effluent 2) metal cations, as well as nitrate, borate, or carbonate anions. The individual sorption isotherms of each main component were measured by the solution depletion method. The differential molar enthalpy changes accompanying the ion-exchange between Cs+ or Sr2+ ions and protons at the resin surface from single-component nitrate solutions were measured by isothermal titration calorimetry and they showed a higher specificity of the two resins toward cesium. Compared to the retention limits of both resins under such idealized conditions, an important depression in the maximum adsorption capacity toward each main component was observed in multication systems. The overall effect of ion exchange process appeared to be an unpredictable outcome of the individual sorption capacities of the two resins toward various cations as a function of the cation charge, size, and concentration. The cesium retention capacity of the resins was diminished to about 25% of the "ideal" value in Effluent 1 and 50% in Effluent 2; a further decrease to about 15% was observed upon concomitant strontium addition. The uptake of strontium by the resins was found to be less sensitive to the addition of other metal components: the greatest decrease in the amount adsorbed was 60% of the ideal value in the two effluents for Amberlite® IRN77 and 75% for Amberlite™ IRN9652. It was therefore demonstrated that any performance tests carried out under idealized conditions should be exploited with much caution to predict the real performance of cation exchange resins under conditions of cation competition.

  16. Synthesis and SMM behaviour of trinuclear versus dinuclear 3d-5f uranyl(v)-cobalt(ii) cation-cation complexes.

    Science.gov (United States)

    Chatelain, Lucile; Tuna, Floriana; Pécaut, Jacques; Mazzanti, Marinella

    2017-01-17

    Trinuclear versus dinuclear heterodimetallic U(V)O2(+)Co(2+) complexes were selectively assembled via a cation-cation interaction by tuning the ligand. The trimeric complex 2, with a linear [Co-O[double bond, length as m-dash]U[double bond, length as m-dash]O-Co] core, exhibits magnetic exchange and slow relaxation with a reversal barrier of 30.5 ± 0.9 K providing the first example of a U-Co exchange-coupled SMM.

  17. Solution behaviour of new cationic surfactants derived from Guerbet alcohols and their use in hair conditioners.

    Science.gov (United States)

    Yahagi, K; Hoshino, N; Hirota, H

    1991-10-01

    Summary The solution behaviour of new cationic surfactants, synthesized by using long-chain Guerbet alcohols, in water was investigated by a polarizing microscopic technique, differential scanning calorimetry, and electric conductivity measurements. These surfactants show the gel-liquid crystalline phase transition to be lower than 0 degrees C and form lamellar liquid crystals even in cold water and at low concentrations of surfactants. The sorption of cationic surfactants from aqueous solutions onto hair was determined as a function of temperature. The effect of adsorbed cationic surfactants on the critical surface tension and kinetic frictional coefficients of hair surface have been investigated. These surface characteristics of hair treated with quaternary ammonium compounds derived from Guerbet alcohols were found to be significantly improved. These results can be explained by the high ability of sorption onto hair. Hair rinses and conditioners having excellent ease of combing or brushing for wet and dry hair can be formulated by the application of these cationic surfactants.

  18. Tunneling Motion and Antiferroelectric Ordering of Lithium Cations Trapped inside Carbon Cages

    Science.gov (United States)

    Aoyagi, Shinobu; Tokumitu, Akio; Sugimoto, Kunihisa; Okada, Hiroshi; Hoshino, Norihisa; Akutagawa, Tomoyuki

    2016-09-01

    Dielectric and X-ray diffraction measurements of [Li@C60](PF6) single crystals reveal the motion of the Li+ cations inside the C60 cages at low temperature. An increase in the dielectric permittivity below 100 K is consistent with a combined tunneling and hopping motion of the Li+ cation between two positions inside the C60 cage. A phase transition accompanied by a decrease in the dielectric permittivity at TC = 24 K is explained by an antiferroelectric ordering of the Li+ cations. The Li+ ordering is caused by interactions among electric dipole moments formed between the Li+ cations inside and the PF6- anions outside the C60 cages. The electric dipole moments that are switched by the Li+ tunneling and interact with each other are potential qubits in a quantum computer using electric dipole moments.

  19. EFFECTS OF PROCESSING OPERATIONS ON ZETA POTENTIAL AND CATIONIC DEMAND OF PULPS

    Institute of Scientific and Technical Information of China (English)

    Nishi K. Bhardwaj; Sanjay Kumar; Pramod K. Bajpai

    2004-01-01

    Thc zeta potential and cationic demands of various kraft pulps - unbleached, bleached and beaten to different freeness levels were determined in the laboratory. The zeta potential of pulp where the final stage was a lignin degrading and dissolving treatment such as alkaline extraction or hypochlorite was lower than the unbleached pulp. The cationic demand of unbleached pulp was higher compared to that of bleached pulp. Beaten pulps showed larger cationic demands than the unbeaten pulps, which can be attributed to the larger specific surface area of pulp components. Fibres become increasingly electronegative when beaten and therefore cationic demand of pulps increases with beating. When the zeta potential method is used with furnishes of different freeness,the linear relationship is observed. However, the slope is decreasing with the decrease in freeness of the pulp.

  20. Separation of Clay Minerals from Host Sediments Using Cation Exchange Resins

    Institute of Scientific and Technical Information of China (English)

    I.S. Ismael; H.M. Baioumy

    2003-01-01

    Classic physical and chemical treatments applied to separating clay minerals from the host sediments are often difficult or aggressive for clay minerals. A technique using cation exchange resins (amberlite IRC-50H and amberlite IR-120) is used to separate clay minerals from the host sediments. The technique is based on the exchange of cations in the minerals that may be associated clay minerals in sediments,such as Ca and Mg from dolomite; Ca from calcite,gypsum and francolite with cations carried by resin radicals. The associated minerals such as gypsum,calcite,dolomite and francolite are removed in descending order. Separation of clay minerals using cation exchange resins is less aggressive than that by other classic treatments.The efficiency of amberlite IRC-50H in the removal of associated minerals is greater than that of amberlite IR-120.

  1. Anion recognition and cation-induced molecular motion in a heteroditopic [2]rotaxane.

    Science.gov (United States)

    Leontiev, Alexandre V; Jemmett, Charlotte A; Beer, Paul D

    2011-01-17

    A heteroditopic [2]rotaxane consisting of a calix[4]diquinone-isophthalamide macrocycle and 3,5-bis-amide pyridinium axle components with the capability of switching between two positional isomers in response to barium cation recognition is synthesised. The anion binding properties of the rotaxane's interlocked cavity together with Na(+) , K(+) , NH(4) (+) and Ba(2+) cation recognition capabilities are elucidated by (1) H NMR and UV-visible spectroscopic titration experiments. Upon binding of Ba(2+) , molecular displacement of the axle's positively charged pyridinium group from the rotaxane's macrocyclic cavity occurs, whereas the monovalent cations Na(+) , K(+) and NH(4) (+) are bound without causing significant co-conformational change. The barium cation induced shuttling motion can be reversed on addition of tetrabutylammonium sulfate.

  2. On the intrinsic optical absorptions by tetrathiafulvalene radical cations and isomers

    DEFF Research Database (Denmark)

    Kirketerp, Maj-Britt Suhr; Leal, Leonardo Andrés Espinosa; Varsano, Daniele;

    2011-01-01

    Gas-phase action spectroscopy shows unambiguously that the low-energy absorptions by tetramethylthiotetrathiafulvalene and tetrathianaphthalene cations in solution phase are due to monomers and not π-dimers....

  3. Pulse radiolysis and spectrophotometric studies on the binding of organic cations with heparin

    Science.gov (United States)

    Jakubowska, Małgorzata; Adamus, Jan; Gębicki, Jerzy; Marcinek, Andrzej; Sikora, Adam

    2014-06-01

    Here we present the spectroscopic and pulse radiolysis studies of the interactions of heparin and some organic cations:methylene blue (MB), 1-methylnicotinamide (MNA+), and its dimer 1,3-bis(1-methylnicotinamide)propane (bis(MNA+)).

  4. Fast repair of purine deoxynucleotide radical cations by rutin and quercetin

    Institute of Scientific and Technical Information of China (English)

    赵晨阳; 石益民; 王文锋; 贾忠建; 姚思德; 范波涛; 郑荣梁

    2001-01-01

    Repair effects of rutin and quercetin on purine deoxynucleotide radical cations were studied using pulse radiolysis technique. On electron pulse irradiation of N2 saturated deoxynucleotide aqueous solution containing 20 mmol/L K2S2O8, 200 mmol/L t-BuOH and rutin or quercetin, the transient absorption spectra of the deoxynucleotide radical cations decayed quickly. At the same time, the spectra of flavonoid phenoxyl radicals formed within several dozen microseconds. The results indicated that deoxynucleotide radical cations can be repaired by flavonoids. The rate constants of the repair reactions were 3.8×108-4.4×108 mol-1·L·s-1 and 1.3×108-1.8×108 mol-1·L·s-1 for dAMP and dGMP radical cations, respectively.

  5. Cation disordering by rapid crystal growth in olivine-phosphate nanocrystals.

    Science.gov (United States)

    Chung, Sung-Yoon; Kim, Young-Min; Lee, Seongsu; Oh, Sang Ho; Kim, Jin-Gyu; Choi, Si-Young; Kim, Youn-Joong; Kang, Suk-Joong L

    2012-06-13

    On the basis of Pauling's first rule for ionic bonding, the coordination number of cations with oxygen anions can be determined by comparison of their relative ionic size ratio. In contrast to simple oxides, various site occupancies by multicomponent cations with similar sizes usually occur in complex oxides, resulting in distinct physical properties. Through an unprecedented combination of in situ high-temperature high-resolution electron microscopy, crystallographic image processing, geometric phase analysis, and neutron powder diffraction, we directly demonstrate that while the initial crystallites after nucleation during crystallization have a very high degree of ordering, significant local cation disordering is induced by rapid crystal growth in Li-intercalation metal-phosphate nanocrystals. The findings in this study show that control of subsequent crystal growth during coarsening is of great importance to attain a high degree of cation ordering, emphasizing the significance of atomic-level visualization in real time.

  6. Preparation and Photochemical Behavior of a Cationic Azobenzene Dye-Montmorillonite Intercalation Compound

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Montmorillonite/cationic azobenzene dye(p-(δ-triethylammoniobutoxy)-p'-methyl-azobenzene bromide) intercalation compounds were prepared by the conventional ion exchange method. As compared with that of pure cationic azo-dye, the thermal stability of the intercalated dye was greatly enhanced, and the absorption band corresponding to azobenzene group in intercalated dye shifted towards longer wave length by 38 nm. This could be ascribed to the strong conjugation of cationic azo-dye supramolecular order structure(J cluster) confined in a nanoscale space of montmorillonite interlayer gallery. UV/vis spectra data show that the intercalated azo dye in the montmorillonite interlayer space exhibited reversible trans-to-cis photoisomerization and daylight cis-to-trans back reaction. FTIR indicates the successful intercalation of cationic azo-dye into the montmorillonite interlayer.

  7. Enthalpy-entropy compensation for n-hexane adsorption on Y zeolite containing transition metal cations

    Directory of Open Access Journals (Sweden)

    Hercigonja R.

    2015-01-01

    Full Text Available In this work, the values of entropy changes related to n-hexane adsorption onto cation exchanged Y zeolite were calculated from differential heats. Various transition metal cations (Co2+, Ni2+, Zn2+ and Cd2+ were introduced into the lattice of the parent NaY, and the existence of enthalpy-entropy compensation effect related to n-hexane adsorption, id. est, the linearity of -ΔH vs. -ΔS plots was examined. The compensation effect was confirmed for all investigated zeolites. The compensation effect can be comprehended as governed by ion-induced dipole interaction between highly polarizing cationic centers in zeolite and nonopolar n-hexane molecules. Finally, the compensation effect and so the compensation temperature were found to depend on the type of charge-balancing cation (charge, size and electronic configuration. [Projekat Ministarstva nauke Republike Srbije, br. 172018

  8. Spectroscopic analysis of 1-butyl-2,3-dimethylimidazolium ionic liquids: Cation-anion interactions

    Science.gov (United States)

    Men, Shuang; Jiang, Jing; Licence, Peter

    2017-04-01

    In this study, four 1-butyl-2,3-dimethylimidazolium ionic liquids are analysed by X-ray photoelectron spectroscopy, together with three 1-butyl-3-methylimidazolium ionic liquids. A reliable fitting model for the carbon 1s region of 1-butyl-2,3-dimethylimidazolium ionic liquids is modified according to established models. The effect of the anion on the electronic environment of the cation is explored based upon the comparison between measured binding energies of nitrogen 1s and the hydrogen bond acceptor ability. The effect of the cation on the cation-anion interaction is also demonstrated by carefully comparing the hydrogen bond donating ability of different cations, with a definite anion.

  9. Adsorption of Cationic Peptides to Solid Surfaces of Glass and Plastic

    DEFF Research Database (Denmark)

    Kristensen, Kasper; Henriksen, Jonas Rosager; Andresen, Thomas Lars

    2015-01-01

    Cationic membrane-active peptides have been studied for years in the hope of developing them into novel types of therapeutics. In this article, we investigate an effect that might have significant experimental implications for investigators who wish to study these peptides, namely, that the pepti......Cationic membrane-active peptides have been studied for years in the hope of developing them into novel types of therapeutics. In this article, we investigate an effect that might have significant experimental implications for investigators who wish to study these peptides, namely......, that the peptides adsorb to solid surfaces of glass and plastic. Specifically, we use analytical HPLC to systematically quantify the adsorption of the three cationic membraneactive peptides mastoparan X, melittin, and magainin 2 to the walls of commonly used glass and plastic sample containers. Our results show...... experiments on cationic membrane-active peptides. We conclude the article by discussing different strategies for reducing the experimental impact of these adsorption effects....

  10. The diastereoselective synthesis of octahedral cationic iridium hydride complexes with a stereogenic metal centre.

    Science.gov (United States)

    Humbert, Nicolas; Mazet, Clément

    2016-08-23

    We report herein the highly diastereoselective synthesis of octahedral cationic Ir(iii) hydride complexes with a stereogenic metal centre following various strategies. The configurational stability of these compounds has also been investigated.

  11. Switchable Pickering emulsions stabilized by silica nanoparticles hydrophobized in situ with a conventional cationic surfactant.

    Science.gov (United States)

    Zhu, Yue; Jiang, Jianzhong; Liu, Kaihong; Cui, Zhenggang; Binks, Bernard P

    2015-03-24

    A stable oil-in-water Pickering emulsion stabilized by negatively charged silica nanoparticles hydrophobized in situ with a trace amount of a conventional cationic surfactant can be rendered unstable on addition of an equimolar amount of an anionic surfactant. The emulsion can be subsequently restabilized by adding a similar trace amount of cationic surfactant along with rehomogenization. This destabilization-stabilization behavior can be cycled many times, demonstrating that the Pickering emulsion is switchable. The trigger is the stronger electrostatic interaction between the oppositely charged ionic surfactants compared with that between the cationic surfactant and the (initially) negatively charged particle surfaces. The cationic surfactant prefers to form ion pairs with the added anionic surfactant and thus desorbs from particle surfaces rendering them surface-inactive. This access to switchable Pickering emulsions is easier than those employing switchable surfactants, polymers, or surface-active particles, avoiding both the complicated synthesis and the stringent switching conditions.

  12. Ammonia vapor sensing properties of polyaniline-titanium(IV)phosphate cation exchange nanocomposite.

    Science.gov (United States)

    Khan, Asif Ali; Baig, Umair; Khalid, Mohd

    2011-02-28

    In this study, the electrically conducting polyaniline-titanium(IV)phosphate (PANI-TiP) cation exchange nanocomposite was synthesized by sol-gel method. The cation exchange nanocomposite based sensor for detection of ammonia vapors was developed at room temperature. It was revealed that the sensor showed good reversible response towards ammonia vapors ranging from 3 to 6%. It was found that the sensor with p-toluene sulphonic acid (p-TSA) doped exhibited higher sensing response than hydrochloric acid doped. This sensor has detection limit ≤1% ammonia. The response of resistivity changes of the cation exchange nanocomposite on exposure to different concentrations of ammonia vapors shows its utility as a sensing material. These studies suggest that the cation exchange nanocomposite could be a good material for ammonia sensor at room temperature.

  13. Synthesis and adsorption properties of the cation exchange forms of OFF-type zeolite

    Science.gov (United States)

    Gorshunova, K. K.; Travkina, O. S.; Kustov, L. M.; Kutepov, B. I.

    2016-03-01

    The possibility of the ion-exchange of Na+ and K+ cations contained in OFF-type zeolite for H+, Ni2+, Cu2+, Co2+, and La3+ cations is investigated. Chemical and phase compositions, the morphology of crystals, and the adsorption properties of synthesized samples are studied via X-ray fluorescence and X-ray diffraction analysis, IR spectroscopy, scanning electron microscopy, and adsorption measurements.

  14. The bisketene radical cation and its formation by oxidative ring-Opening of cyclobutenedione

    OpenAIRE

    Piech, Krzysztof; Bally, Thomas; Allen, Annette D.; Tidwell, Thomas T.

    2013-01-01

    Parent cyclobutenedione 1 was photolyzed and ionized in an Ar matrix at 10K. The bisketene 2 that results in both cases (in the form of its radical cation after ionization) was characterized by its IR spectrum and by high-level quantum chemical calculations. Experiment and theory show that the neutral bisketene has only a single conformation where the two ketene moieties are nearly perpendicular, whereas the radical cation is present in two stable planar conformations. The mechanism of the ri...

  15. Exchangeable cations-mediated photodegradation of polycyclic aromatic hydrocarbons (PAHs) on smectite surface under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Hanzhong, E-mail: jiahz@ms.xjb.ac.cn [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Li, Li [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Chen, Hongxia; Zhao, Yue [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); School of Geology and Mining Engineering, Xinjiang University, Urumqi 830046 (China); Li, Xiyou [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Wang, Chuanyi, E-mail: cywang@ms.xjb.ac.cn [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China)

    2015-04-28

    Graphical abstract: Roles of exchangeable cations in PAHs photodegradation on clay surafces under visible light. - Highlights: • Photolysis rate are strongly dependent on the type of cations on clay surface. • The strength of “cation–π” interactions governs the photodegradation rate of PAHs. • Several exchangeable cations could cause a shift in the absorption spectrum of PAHs. • Exchangeable cations influence the type and amount of reactive intermediates. - Abstract: Clay minerals saturated with different exchangeable cations are expected to play various roles in photodegradation of polycyclic aromatic hydrocarbons (PAHs) via direct and/or indirect pathways on clay surfaces. In the present study, anthracene and phenanthrene were selected as molecule probes to investigate the roles of exchangeable cations on their photodegradation under visible light irradiation. For five types of cation-modified smectite clays, the photodegradation rate of anthracene and phenanthrene follows the order: Fe{sup 3+} > Al{sup 3+} > Cu{sup 2+} >> Ca{sup 2+} > K{sup +} > Na{sup +}, which is consistent with the binding energy of cation–π interactions between PAHs and exchangeable cations. The result suggests that PAHs photolysis rate depends on cation–π interactions on clay surfaces. Meanwhile, the deposition of anthracene at the Na{sup +}-smectite and K{sup +}-smectite surface favors solar light absorption, resulting in enhanced direct photodecomposition of PAHs. On the other hand, smectite clays saturated with Fe{sup 3+}, Al{sup 3+}, and Cu{sup 2+} are highly photoreactive and can act as potential catalysts giving rise to oxidative radicals such as O{sub 2}{sup −}· , which initiate the transformation of PAHs. The present work provides valuable insights into understanding the transformation and fate of PAHs in the natural soil environment and sheds light on the development of technologies for contaminated land remediation.

  16. The generation and spectral characterization of oligothiophenes radical cations. A pulse radiolysis investigation

    Energy Technology Data Exchange (ETDEWEB)

    Emmi, S.S. [Istituto FRAE of CNR, Via P. Gobetti 101, 40129 Bologna (Italy); D' Angelantonio, M. [Istituto FRAE of CNR, Via P. Gobetti 101, 40129 Bologna (Italy); Beggiato, G. [Istituto FRAE of CNR, Via P. Gobetti 101, 40129 Bologna (Italy); Poggi, G. [Dipartimento ' G. Ciamician' , Universita di Bologna, Via Selmi 2, 40126 Bologna (Italy); Geri, A. [Istituto FRAE of CNR, Via P. Gobetti 101, 40129 Bologna (Italy); Pietropaolo, D. [Istituto ICOCEA of CNR, Via P. Gobetti 101, 40129 Bologna (Italy); Zotti, G. [Istituto IPELP of CNR, C.so Stati Uniti 4, 35020 Padova (Italy)

    1999-03-01

    Conjugated polymers and oligomers of thiophene have been employed in a number of electronic devices due to the change in their conductivity by several orders of magnitude when oxidized to their cationic states. The radical cations of oligothiophenes (nT), with number of rings n=1-6, have been produced by pulse radiolysis for the first time and their spectra have been characterized. Electronic structure and transition energies are briefly discussed in the light of semiempirical theoretical calculations.

  17. Ternary mixtures of ionic liquids for better salt solubility, conductivity and cation transference number improvement

    Science.gov (United States)

    Karpierz, E.; Niedzicki, L.; Trzeciak, T.; Zawadzki, M.; Dranka, M.; Zachara, J.; Żukowska, G. Z.; Bitner-Michalska, A.; Wieczorek, W.

    2016-01-01

    We hereby present the new class of ionic liquid systems in which lithium salt is introduced into the solution as a lithium cation−glyme solvate. This modification leads to the reorganisation of solution structure, which entails release of free mobile lithium cation solvate and hence leads to the significant enhancement of ionic conductivity and lithium cation transference numbers. This new approach in composing electrolytes also enables even three-fold increase of salt concentration in ionic liquids. PMID:27767069

  18. Alkali metal-cationized serine clusters studied by sonic spray ionization tandem mass spectrometry.

    Science.gov (United States)

    Nanita, Sergio C; Sokol, Ewa; Cooks, R Graham

    2007-05-01

    Serine solutions containing salts of alkali metals yield magic number clusters of the type (Ser(4)+C)(+), (Ser(8)+C)(+), (Ser(12)+C)(+), and (Ser(17)+2C)(+2) (where C = Li(+), Na(+), K(+), Rb(+), or Cs(+)), in relative abundances which are strongly dependent on the cation size. Strong selectivity for homochirality is involved in the formation of serine tetramers cationized by K(+), Rb(+), and Cs(+). This is also the case for the octamers cationized by the smaller alkalis but there is a strong preference for heterochirality in the octamers cationized by the larger alkali cations. Tandem mass spectrometry shows that the octamers and dodecamers cationized by K(+), Rb(+), and Cs(+) dissociate mainly by the loss of Ser(4) units, suggesting that the neutral tetramers are the stable building blocks of the observed larger aggregates, (Ser(8)+C)(+) and (Ser(12)+C)(+). Remarkably, although the Ser(4) units are formed with a strong preference for homochirality, they aggregate further regardless of their handedness and, therefore, with a preference for the nominally racemic 4D:4L structure and an overall strong heterochiral preference. The octamers cationized by K(+), Rb(+), or Cs(+) therefore represent a new type of cluster ion that is homochiral in its internal subunits, which then assemble in a random fashion to form octamers. We tentatively interpret the homochirality of these tetramers as a consequence of assembly of the serine molecules around a central metal ion. The data provide additional evidence that the neutral serine octamer is homochiral and is readily cationized by smaller ions.

  19. Tunable separation of anions and cations by column switching in ion chromatography.

    Science.gov (United States)

    Amin, Muhammad; Lim, Lee Wah; Takeuchi, Toyohide

    2007-03-15

    A convenient ion chromatography method has been proposed for the routine and simple determination of anions (Cl(-), SO(4)(2-) and NO(3)(-)) and/or cations (Na(+), NH(4)(+), K(+), Mg(2+) and Ca(2+)) using a single pump, a single eluent and a single detector. The present system used cation-exchange and anion-exchange columns connected in series via two 6-port switching valves or a single 10-port valve. The connection order of the ion-exchange columns could be varied by switching the valve(s). The present system therefore allowed the separation of either cations or anions in a single chromatographic run. While one ion-exchange column is being operated, the other ion-exchange column is being conditioned, i.e., the columns are always ready for analysis at any time. When 2.4mM 5-sulfosalicylic acid was used as the eluent, the three anions and the five cations could be separated on the anion-exchange column and cation-exchange column, respectively. In order to obtain the separations of the target ions, the injection valve was placed between the two columns. Complete separations of the above anions or cations were demonstrated within 10min each. The detection limits at S/N=3 were 19-50ppb (mug/l) for cations and 10-14ppb for anions. The relative standard deviations of the analyte ions were less than 1.1, 2.9 and 2.8% for retention time, peak area and peak height, respectively. This proposed technique was applied to the determination of common anions and cations in river water samples.

  20. Mixed-Valence Porphyrin π-Cation Radical Derivatives: Electrochemical Investigations.

    Science.gov (United States)

    Scheidt, W Robert; Buentello, Kristin E; Ehlinger, Noelle; Cinquantini, Arnaldo; Fontani, Marco; Laschi, Franco

    2008-05-05

    The electrochemistry of [Cu(OEP)] and [Ni(OEP)] are compared with the mixed-valence π-cations [Cu(OEP•/2)]2+and[Ni(OEP•/2)]2+. These electrochemical studies, carried out with cyclic voltametry and hydrodynamic voltametry, show that the mixed valence π-cations have distinct electrochemical properties, although the differences between the [M(OEP)](+/0) and [M(OEP•/2)]2+/0 processes are subtle.

  1. Theoretical Infrared Spectra for Polycyclic Aromatic Hydrocarbon Neutrals, Cations and Anions

    Science.gov (United States)

    Langhoff, Stephen R.

    1995-01-01

    Calculations are carried out using density functional theory (DFT) to determine the harmonic frequencies and intensities of the neutrals and cations of thirteen polycyclic aromatic hydrocarbons (PAHs) up to the size of ovalene. Calculations are also carried out for a few PAH anions. The DFT harmonic frequencies, when uniformly scaled by the factor of 0.958 to account primarily for anharmonicity, agree with the matrix isolation fundamentals to within an average error of about 10 per centimeter. Electron correlation is found to significantly reduce the intensities of many of the cation harmonics, bringing them into much better agreement with the available experimental data. While the theoretical infrared spectra agree well with the experimental data for the neutral systems and for many of the cations, there are notable discrepancies with the experimental matrix isolation data for some PAH cations that are difficult to explain in terms of limitations in the calculations. In agreement with previous theoretical work, the present calculations show that the relative intensities for the astronomical unidentified infrared (UIR) bands agree reasonably well with those for a distribution of polycyclic aromatic hydrocarbon (PAH) cations, but not with a distribution of PAH neutrals. We also observe that the infrared spectra of highly symmetrical cations such as coronene agree much better with astronomical observations than do those of, for example, the polyacenes such as tetracene and pentacene. The total integrated intensities for the neutral species are found to increase linearly with size, while the total integrated intensities are much larger for the cations and scale more nearly quadratically with size. We conclude that emission from moderate-sized highly symmetric PAH cations such as coronene and larger could account for the UIR bands.

  2. Influence of divalent cations and pH adsorption of a bacterial polysaccharide adhesin

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Suci, P.A.; Baty, A.M.; Weiner, R.M.; Geesey, G.G.

    is important. Evidence for significant participation of hydrogen bonding to the oxide surface is lacking. © 1998 Academic Press Key Words: adhesion; bacteria; polysaccharide; adsorption; di- valent cation. INTRODUCTION Attachment of microorganisms to inert....00 Copyright © 1998 by Academic Press All rights of reproduction in any form reserved. cations and of pH on the adsorption behavior of fr2ps in order to further investigate the interactions involved in bonding of this adhesive polysaccharide at an aqueous...

  3. Cation exchange at the secondary building units of metal–organic frameworks

    OpenAIRE

    Brozek, Carl Kavanaugh; Dinca, Mircea

    2014-01-01

    Cation exchange is an emerging synthetic route for modifying the secondary building units (SBUs) of metal–organic frameworks (MOFs). This technique has been used extensively to enhance the properties of nanocrystals and molecules, but the extent of its applications for MOFs is still expanding. To harness cation exchange as a rational tool, we need to elucidate its governing factors. Not nearly enough experimental observations exist for drawing these conclusions, so we provide a conceptual fra...

  4. Conformational control in a bipyridine linked π-conjugated oligomer: cation mediated helix unfolding and refolding.

    Science.gov (United States)

    Divya, Kizhumuri P; Sreejith, Sivaramapanicker; Suresh, Cherumuttathu H; Ajayaghosh, Ayyappanpillai

    2010-11-28

    A chiral π-conjugated oligomer having alternate bipyridine and carbazole moieties connected through acetylinic bonds undergoes helical folding in chloroform-acetonitrile (40/60, v/v) as evident by fluorescence and circular dichroism changes. In the presence of transition metal cations such as Zn(2+) defolding of the helical conformation occurs. Upon decomplexation of the cation with EDTA, the helical conformation is regained.

  5. SYNTHESIS, CHARACTERIZATION AND QUENCHING BEHAVIOR OF A CATIONIC POLY(p-PHENYLENEVINYLENE) RELATED COPOLYMER

    Institute of Scientific and Technical Information of China (English)

    Guang-wei Zhang; Qu-li Fan; Yan-qin Huang; Wei Huang

    2009-01-01

    A cationic poly(p-phenylene vinylene) related copolymer without bulky phenylene substitutents attached to the conjugated backbone was prepared through Wittig reaction. The molecular structure and optical properties were highly investigated through ~1H-NMR, UV and PL spectroscopy. The quenching behavior was also investigated, and the results demonstrate that incomplete quenching exists, which is consistent with the cationic poly(p-phenylene vinylene) related copolymer containing bulky phenylene substitutents, probably correlated with the conformation of conjugated backbone and intermolecular aggregation.

  6. Cationic surfactants derived from lysine: effects of their structure and charge type on antimicrobial and hemolytic activities.

    Science.gov (United States)

    Colomer, A; Pinazo, A; Manresa, M A; Vinardell, M P; Mitjans, M; Infante, M R; Pérez, L

    2011-02-24

    Three different sets of cationic surfactants from lysine have been synthesized. The first group consists of three monocatenary surfactants with one lysine as the cationic polar head with one cationic charge. The second consists of three monocatenary surfactants with two amino acids as cationic polar head with two positive charges. Finally, four gemini surfactants were synthesized in which the spacer chain and the number and type of cationic charges have been regulated. The micellization process, antimicrobial activity, and hemolytic activity were evaluated. The critical micelle concentration was dependent only on the hydrophobic character of the molecules. Nevertheless, the antimicrobial and hemolytic activities were related to the structure of the compounds as well as the type of cationic charges. The most active surfactants against the bacteria were those with a cationic charge on the trimethylated amino group, whereas all of these surfactants showed low hemolytic character.

  7. Pulse radiolysis studies of aminobenzenesulfonates: Formation of cation radicals. [7 MeV electrons

    Energy Technology Data Exchange (ETDEWEB)

    Behar, D.; Behar, B. (Univ. of Notre Dame, IN (United States))

    1991-09-19

    Sulfanilic acid and anilinedisulfonic acids (ADS) react with OH radicals (k = 8.2 {times} 10{sup 9} and 5.9 {times} 10{sup 9} M{sup {minus}1}s{sup {minus}1}) to form the corresponding OH adducts. In acid solutions the adducts react with protons to yield cation radicals (k = 5.3 {times} 10{sup 8} and 8.7 {times} 10{sup 8} M{sup {minus}1}s{sup {minus}1}). N{sub 3} oxidizes sulfanilic acid directly to the cation radical by an electron-transfer reaction at a diffusion-controlled rate constant, k = 6.5 {times} 10{sup 9}M{sup {minus}1}s{sup {minus}1}, while the rate of oxidation of ADS by N{sub 3} is only 7.6 {times} 10{sup 7} M{sup {minus}1}s{sup {minus}1}. SO{sub 4}{sup {minus}} on the other hand oxidizes ADS to the cation radical at a rate of 1.8 {times} 10{sup 9}M{sup {minus}1}s{sup {minus}1}. Both cation radicals deprotonate to the anilino-type radicals in acid-base equilibria. The pK{sub a} of deprotonation of the sulfanilic cation radical is 5.8 {plus minus} 0.05 and that of the ADS cation radical is 4.3 {plus minus} 0.05.

  8. On the energetics of cation ordering in tungsten-bronze-type oxides.

    Science.gov (United States)

    Olsen, Gerhard Henning; Selbach, Sverre Magnus; Grande, Tor

    2015-11-11

    Oxides with the tetragonal tungsten bronze (TTB) structure are well-known ferroelectrics that show a large flexibility both with respect to chemical composition and cation ordering. Two of the simplest compounds in this family are lead metaniobate (PbNb2O6 or PN) and strontium barium niobate (SrxBa1-xNb2O6 or SBN). While PN is a classical ferroelectric, SBN goes from ferroelectric to relaxor-like with increasing Sr content, with a polar direction different from that in PN. The partially occupied sublattices in both systems give the possibility for cation order-disorder phenomena, but it is not known if or how this influences the polarization and ferroelectricity. Here, we use density functional theory (DFT) calculations to investigate how cation and cation vacancy ordering influences the energetics of these compounds, by comparing both the energy differences and the barriers for transition between different cation configurations. We extend the thermodynamic model of O'Neill and Navrotsky, originally developed for cation interchange in spinels, to describe the order-disorder phenomenology in TTB oxides. The influence of order-disorder processes on the functional properties of PN and SBN is discussed.

  9. Novel cationic SLN containing a synthesized single-tailed lipid as a modifier for gene delivery

    Energy Technology Data Exchange (ETDEWEB)

    Yu Wangyang; Liu Chunxi; Ye Jiesheng; Zou Weiwei; Zhang Na; Xu Wenfang [School of Pharmaceutical Sciences, Shandong University, 44 Wenhua Xi Road, Ji' nan (China)], E-mail: zhangnancy9@sdu.edu.cn

    2009-05-27

    Cationic solid lipid nanoparticles (SLN) can bind DNA directly via ionic interaction and mediate in vitro gene transfection. However, toxicity is still an obstacle, which is strongly dependent on the cationic lipid used. In the present study, a novel single-tailed cationic lipid, 6-lauroxyhexyl lysinate (LHLN), was synthesized and used as a modifier to prepare stable SLN-DNA complexes by a nanoprecipitation method. The commonly used cationic lipid cetyltrimethylammonium bromide (CTAB) modified SLN-DNA formulation served as a contrast. These two formulations were characterized and compared in terms of morphology, particle size, surface charge, DNA binding capacity, release profile, cytotoxicity, and transfection efficiency. The LHLN SLN-DNA complexes had a similar spherical morphology, a relatively narrow particle size distribution and a more remarkable DNA loading capability compared to the CTAB ones. Most importantly, LHLN modified SLN had a higher gene transfection efficiency than the naked DNA and CTAB ones, which was approximately equal to that of Lipofectamine-DNA complexes, and a lower cytotoxicity compared with CTAB-SLN and Lipofectamine 2000. Thus, the novel cationic SLN can achieve efficient transfection of plasmid DNA, and to some extent reduce the cytotoxicity, which might overcome some drawbacks of the conventional cationic nanocarriers in vivo and may become a promising non-viral gene therapy vector.

  10. Novel cationic SLN containing a synthesized single-tailed lipid as a modifier for gene delivery

    Science.gov (United States)

    Yu, Wangyang; Liu, Chunxi; Ye, Jiesheng; Zou, Weiwei; Zhang, Na; Xu, Wenfang

    2009-05-01

    Cationic solid lipid nanoparticles (SLN) can bind DNA directly via ionic interaction and mediate in vitro gene transfection. However, toxicity is still an obstacle, which is strongly dependent on the cationic lipid used. In the present study, a novel single-tailed cationic lipid, 6-lauroxyhexyl lysinate (LHLN), was synthesized and used as a modifier to prepare stable SLN-DNA complexes by a nanoprecipitation method. The commonly used cationic lipid cetyltrimethylammonium bromide (CTAB) modified SLN-DNA formulation served as a contrast. These two formulations were characterized and compared in terms of morphology, particle size, surface charge, DNA binding capacity, release profile, cytotoxicity, and transfection efficiency. The LHLN SLN-DNA complexes had a similar spherical morphology, a relatively narrow particle size distribution and a more remarkable DNA loading capability compared to the CTAB ones. Most importantly, LHLN modified SLN had a higher gene transfection efficiency than the naked DNA and CTAB ones, which was approximately equal to that of Lipofectamine-DNA complexes, and a lower cytotoxicity compared with CTAB-SLN and Lipofectamine 2000. Thus, the novel cationic SLN can achieve efficient transfection of plasmid DNA, and to some extent reduce the cytotoxicity, which might overcome some drawbacks of the conventional cationic nanocarriers in vivo and may become a promising non-viral gene therapy vector.

  11. Purification and characterization of a cationic peroxidase Cs in Raphanus sativus.

    Science.gov (United States)

    Kim, Soung Soo; Lee, Dong Ju

    2005-06-01

    A short distance migrating cationic peroxidase from Korean radish seeds (Raphanus sativus) was detected. Cationic peroxidase Cs was purified to apparent homogeneity and characterized. The molecular mass of the purified cationic peroxidase Cs was estimated to be about 44 kDa on SDS-PAGE. After reconstitution of apoperoxidase Cs with protohemin, the absorption spectra revealed a new peak in the Soret region around 400 nm, which is typical in a classical type III peroxidase family. The optimum pH of peroxidase activity for o-dianisidine oxidation was observed at pH 7.0. Kinetic studies revealed that the reconstituted cationic peroxidase Cs has Km values of 1.18 mM and of 1.27 mM for o-dianisidine and H2O2, respectively. The cationic peroxidase Cs showed the peroxidase activities for native substrates, such as coumaric acid, ferulic acid, and scopoletin. This result suggested that cationic peroxidase Cs plays an important role in plant cell wall formation during seed germination.

  12. Hydrocolloid liquid-core capsules for the removal of heavy-metal cations from water.

    Science.gov (United States)

    Nussinovitch, A; Dagan, O

    2015-12-15

    Liquid-core capsules with a non-crosslinked alginate fluidic core surrounded by a gellan membrane were produced in a single step to investigate their ability to adsorb heavy metal cations. The liquid-core gellan-alginate capsules, produced by dropping alginate solution with magnesium cations into gellan solution, were extremely efficient at adsorbing lead cations (267 mg Pb(2+)/g dry alginate) at 25 °C and pH 5.5. However, these capsules were very weak and brittle, and an external strengthening capsule was added by using magnesium cations. The membrane was then thinned with the surfactant lecithin, producing capsules with better adsorption attributes (316 mg Pb(+2)/g dry alginate vs. 267 mg Pb(+2)/g dry alginate without lecithin), most likely due to the thinner membrane and enhanced mass transfer. The capsules' ability to adsorb other heavy-metal cations - copper (Cu(2+)), cadmium (Cd(2+)) and nickel (Ni(2+)) - was tested. Adsorption efficiencies were 219, 197 and 65 mg/g, respectively, and were correlated with the cation's affinity to alginate. Capsules with the sorbed heavy metals were regenerated by placing in a 1M nitric acid suspension for 24h. Capsules could undergo three regeneration cycles before becoming damaged.

  13. Cationic amphiphiles with fatty acyl chain asymmetry of coconut oil deliver genes selectively to mouse lung.

    Science.gov (United States)

    Chandrashekhar, Voshavar; Srujan, Marepally; Prabhakar, Rairala; Reddy, Rakesh C; Sreedhar, Bojja; Rentam, Kiran K R; Kanjilal, Sanjit; Chaudhuri, Arabinda

    2011-03-16

    Recent structure-activity studies have revealed a dramatic influence of hydrophobic chain asymmetry in enhancing gene delivery efficacies of synthetic cationic amphiphiles (Nantz, M. H. et al. Mol. Pharmaceutics2010, 7, 786-794; Koynova, R. et al. Mol. Pharmaceutics2009, 6, 951-958). The present findings demonstrate for the first time that such a transfection enhancing influence of asymmetric hydrocarbon chains observed in pure synthetic cationic amphiphiles also works for cationic amphiphiles designed with natural, asymmetric fatty acyl chains of a food-grade oil. Herein, we demonstrate that cationic amphiphiles designed with the natural fatty acyl chain asymmetry of food-grade coconut oil are less cytotoxic and deliver genes selectively to mouse lung. Despite lauroyl chains being the major fatty acyl chains of coconut oil, both the in vitro and In vivo gene transfer efficiencies of such cationic amphiphiles were found to be remarkably superior (>4-fold) to those of their pure dilauroyl analogue. Mechanistic studies involving the technique of fluorescence resonance energy transfer (FRET) revealed higher biomembrane fusibility of the cationic liposomes of the coconut amphiphiles than that of the symmetric dilauroyl analogue. AFM study revealed pronounced fusogenic nonlamellar structures of the liposomes of coconut amphiphiles. Findings in the FRET and cellular uptake study, taken together, support the notion that the higher cellular uptake resulting from the more fusogenic nature of the liposomes of coconut amphiphiles 1 are likely to play a dominant role in making the coconut amphiphiles transfection competent.

  14. Enhanced Mixed Electronic-Ionic Conductors through Cation Ordering

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Allan J. [Univ. of Houston, TX (United States); Morgan, Dane [Univ. of Wisconsin, Madison, WI (United States); Grey, Clare [Stony Brook Univ., NY (United States)

    2014-08-31

    The performance of many energy conversion and storage devices depend on the properties of mixed ionic-electronic conducting (miec) materials. Mixed or ambipolar conductors simultaneously transport ions and electrons and provide the critical interface between chemical and electrical energy in devices such as fuel cells, ion transport membranes, and batteries. Enhancements in storage capacity, reversibility, power density and device lifetime all require new materials and a better understanding of the fundamentals of ambipolar conductivity and surface reactivity.The high temperature properties of the ordered perovksites AA’B2O5+x, where A = rare earth ion, Y and B = Ba, Sr were studied. The work was motivated by the high oxygen transport and surface exchange rates observed for members of this class of mixed ionic and electronic conductors. A combined experimental and computational approach, including structural, electrochemical, and transport characterization and modeling was used. The approach attacks the problem simultaneously at global (e.g., neutron diffraction and impedance spectroscopy), local (e.g., pair distribution function, nuclear magnetic resonance) and molecular (ab initio thermokinetic modeling) length scales. The objectives of the work were to understand how the cation and associated anion order lead to exceptional ionic and electronic transport properties and surface reactivity in AA’B2O5+x perovskites. A variety of compounds were studied by X-ray and neutron diffraction, measurements of thermodynamics and transport and theoretically. These included PrBaCo2O5+x and NdBaCo2O5+x, PrBaCo2-xFexO6- δ (x = 0, 0.5, 1.0, 1.5 and 2) and LnBaCoFeO6- δ (Ln = La, Pr, Nd, Sm, Eu and Gd), Sr3YCo4O10.5, YBaMn2O5+x. A0.5A’0.5BO3 (where A=Y, Sc, La, Ce, Pr, Nd, Pm, Sm; A’= Sr

  15. Infrared multiple photon dissociation action spectroscopy of sodium cationized halouracils: Effects of sodium cationization and halogenation on gas-phase conformation

    NARCIS (Netherlands)

    Kaczan, C.M.; Rathur, A.I.; Wu, R.R.; Chen, Y.; Austin, C.A.; Berden, G.; Oomens, J.; Rodgers, M.T.

    2015-01-01

    The gas-phase structures of sodium cationized complexes of 5- and 6-halo-substituted uracils are examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical electronic structure calculations. The halouracils examined in this investigation include: 5-flourouracil, 5

  16. Formation of cationic [RP5Cl](+)-cages via insertion of [RPCl](+)-cations into a P-P bond of the P4 tetrahedron.

    Science.gov (United States)

    Holthausen, Michael H; Feldmann, Kai-Oliver; Schulz, Stephen; Hepp, Alexander; Weigand, Jan J

    2012-03-19

    Fluorobenzene solutions of RPCl(2) and a Lewis acid such as ECl(3) (E = Al, Ga) in a 1:1 ratio are used as reactive sources of chlorophosphenium cations [RPCl](+), which insert into P-P bonds of dissolved P(4). This general protocol represents a powerful strategy for the synthesis of new cationic chloro-substituted organophosphorus [RP(5)Cl](+)-cages as illustrated by the isolation of several monocations (21a-g(+)) in good to excellent yields. For singular reaction two possible reaction mechanisms are proposed on the basis of quantum chemical calculations. The intriguing NMR spectra and structures of the obtained cationic [RP(5)Cl](+)-cages are discussed. Furthermore, the reactions of dichlorophosphanes and the Lewis acid GaCl(3) in various stoichiometries are investigated to obtain a deeper understanding of the species involved in these reactions. The formation of intermediates such as RPCl(2)·GaCl(3) (14) adducts, dichlorophosphanylchlorophosphonium cations [RPCl(2)-RPCl](+) (16(+)) and [RPCl(2)-RPCl-GaCl(3)](+) (17(+)) in reaction mixtures of RPCl(2) and GaCl(3) in fluorobenzene strongly depends on the basicity of the dichlorophosphane RPCl(2) (R = tBu, Cy, iPr, Et, Me, Ph, C(6)F(5)) and the reaction stoichiometry.

  17. The Prowess of Photogenerated Amine Radical Cations in Cascade Reactions: From Carbocycles to Heterocycles.

    Science.gov (United States)

    Morris, Scott A; Wang, Jiang; Zheng, Nan

    2016-09-20

    Cascade reactions represent a class of ideal organic reactions because they empower efficiency, elegance, and novelty. However, development of cascade reactions remains a daunting task for synthetic chemists. Radicals are known to be well suited for cascade reactions. Compared with widely used carbon-based radicals, nitrogen-based radicals, such as neutral aminyl radicals and protonated aminyl radicals (amine radical cations), are underutilized, although they are behind some notable synthetic methods such as the Hofmann-Löffler-Freytag reaction. The constraint on their usage is generally attributed to the limited number of available stable precursors. Since amine radical cations offer increased reactivity and selectivity in chemical transformations compared with neutral aminyl radicals, their generation is of utmost importance. Recently, a surge of reports has been revealed using visible light photoredox catalysis. It has been demonstrated that amines can act as an electron donor in a reductive quenching cycle while the amine itself is oxidized to the amine radical cation. Although a number of methods exist to generate amine radical cations, the photochemical formation of these species offers many practical advantages. In this Account, we discuss our journey to the development of annulation reactions with various π-bonds and electrophilic addition reactions to alkenes using photogenerated amine radical cations. Various carbocycles and heterocycles are produced by these reactions. In our annulation work, we first show that single electron photooxidation of cyclopropylanilines to the amine radical cations triggers ring opening of the strained carbocycle, producing distonic radical cations. These odd-electron species are shown to react with alkenes and alkynes to yield the corresponding cyclopentanes and cyclopentenes in an overall redox neutral process. Further development of this annulation reaction allows us to achieve the [4 + 2] annulation of cyclobutylanilines

  18. Genetic basis of chronic pancreatitis

    NARCIS (Netherlands)

    Jansen, JBMJ; Morsche, RT; van Goor, Harry; Drenth, JPH

    2002-01-01

    Background: Pancreatitis has a proven genetic basis in a minority of patients. Methods: Review of the literature on genetics of pancreatitis. Results: Ever since the discovery that in most patients with hereditary pancreatitis a mutation in the gene encoding for cationic trypsinogen (R122H) was foun

  19. Does Cation Size Affect Occupancy and Electrostatic Screening of the Nucleic Acid Ion Atmosphere?

    Science.gov (United States)

    Gebala, Magdalena; Bonilla, Steve; Bisaria, Namita; Herschlag, Daniel

    2016-08-31

    Electrostatics are central to all aspects of nucleic acid behavior, including their folding, condensation, and binding to other molecules, and the energetics of these processes are profoundly influenced by the ion atmosphere that surrounds nucleic acids. Given the highly complex and dynamic nature of the ion atmosphere, understanding its properties and effects will require synergy between computational modeling and experiment. Prior computational models and experiments suggest that cation occupancy in the ion atmosphere depends on the size of the cation. However, the computational models have not been independently tested, and the experimentally observed effects were small. Here, we evaluate a computational model of ion size effects by experimentally testing a blind prediction made from that model, and we present additional experimental results that extend our understanding of the ion atmosphere. Giambasu et al. developed and implemented a three-dimensional reference interaction site (3D-RISM) model for monovalent cations surrounding DNA and RNA helices, and this model predicts that Na(+) would outcompete Cs(+) by 1.8-2.1-fold; i.e., with Cs(+) in 2-fold excess of Na(+) the ion atmosphere would contain an equal number of each cation (Nucleic Acids Res. 2015, 43, 8405). However, our ion counting experiments indicate that there is no significant preference for Na(+) over Cs(+). There is an ∼25% preferential occupancy of Li(+) over larger cations in the ion atmosphere but, counter to general expectations from existing models, no size dependence for the other alkali metal ions. Further, we followed the folding of the P4-P6 RNA and showed that differences in folding with different alkali metal ions observed at high concentration arise from cation-anion interactions and not cation size effects. Overall, our results provide a critical test of a computational prediction, fundamental information about ion atmosphere properties, and parameters that will aid in the

  20. On the Expressiveness of the Approach to Constructing PLC-programs by LTL-Specification

    Directory of Open Access Journals (Sweden)

    E. V. Kuzmin

    2015-01-01

    Full Text Available The article is devoted to the approach to constructing and verification of discrete PLC-programs by LTL-specification. This approach provides an ability of correctness analysis of PLC-programs by the model checking method. The linear temporal logic LTL is used as a language of specification of the program behavior. The correctness analysis of LTL-specification is automatically performed by the symbolic model checking tool Cadence SMV. The article demonstrates the consistency of the approach to constructing and verification of PLC programs by LTL-specification from the point of view of Turing power. It is proved, that in accordance with this approach for any Minsky counter machine can be built an LTL-specification, which is used for machine implementation in any PLC programming language of standard IEC 61131-3. Minsky machines equipollent Turing machines, and the considered approach also has Turing power. The proof focuses on representation of a counter machine behavior in the form of a set of LTL-formulas and matching these formulas to constructions of ST and SFC languages. SFC is interesting as a specific graphical language. ST is considered as a basic language because an implementation of a counter machine in IL, FBD/CFC and LD languages is reduced to rewriting blocks of ST-program. The idea of the proof is demonstrated by an example of a Minsky 3-counter machine, which implements a function of squaring.

  1. Hemin/G-quadruplex structure and activity alteration induced by magnesium cations.

    Science.gov (United States)

    Kosman, J; Juskowiak, B

    2016-04-01

    The influence of metal cations on G-quadruplex structure and peroxidase-mimicking DNAzyme activity was investigated. Experiments revealed a significant role of magnesium ion, which in the presence of potassium cation influenced DNAzyme activity. This ability has been associated with alteration of G-quadruplex topology and consequently affinity to bind hemin molecule. It has been demonstrated that G-quadruplex based on PS2.M sequence under these conditions formed parallel topology, which exhibited lower activity than that observed in standard potassium-containing solution. On the other hand DNAzyme/magnesium ion system based on telomeric sequence, which did not undergo significant structural changes, exhibited higher peroxidase activity upon magnesium ion addition. In both cases, the stabilization effect of magnesium cations on G-quadruplex structure was observed. The mechanism of DNAzyme activity alteration by magnesium ion can be explained by its influence on the pKa value of DNAzyme. Magnesium ion decreased pKa for PS2.M based system but increased it for telomeric DNAzyme. Magnesium cation effect on G-quadruplex structure as well as DNAzyme activity is particularly important since this ion is one of the most common metal cations in biological samples.

  2. Colloid Facilitated Transport of Radioactive Cations in the Vadose Zone: Field Experiments Oak Ridge

    Energy Technology Data Exchange (ETDEWEB)

    James E. Saiers

    2012-09-20

    The overarching goal of this study was to improve understanding of colloid-facilitated transport of radioactive cations through unsaturated soils and sediments. We conducted a suite of laboratory experiments and field experiments on the vadose-zone transport of colloids, organic matter, and associated contaminants of interest to the U.S. Department of Energy (DOE). The laboratory and field experiments, together with transport modeling, were designed to accomplish the following detailed objectives: 1. Evaluation of the relative importance of inorganic colloids and organic matter to the facilitation of radioactive cation transport in the vadose zone; 2. Assessment of the role of adsorption and desorption kinetics in the facilitated transport of radioactive cations in the vadose zone; 3. Examination of the effects of rainfall and infiltration dynamics and in the facilitated transport of radioactive cations through the vadose zone; 4. Exploration of the role of soil heterogeneity and preferential flow paths (e.g., macropores) on the facilitated transport of radioactive cations in the vadose zone; 5. Development of a mathematical model of facilitated transport of contaminants in the vadose zone that accurately incorporates pore-scale and column-scale processes with the practicality of predicting transport with readily available parameters.

  3. Preparation of weak cation exchange packings for chromatographic separation of proteins using "click chemistry''.

    Science.gov (United States)

    Zhao, Kailou; Bai, Quan; Song, Chao; Wang, Fei; Yang, Fan

    2012-04-01

    "Click chemistry" is defined as a class of robust and selective chemical reactions affording high yields and is tolerant to a variety of solvents (including water), functional groups, and air. In this study, click chemistry was used as an effective strategy for coupling three alkyne-carboxylic acids onto the azide-silica to obtain three novel stationary phases of weak cation exchange chromatography, which were characterized with FTIR and elemental analysis. Six kinds of standard proteins, such as myoglobin, RNase A, RNase B, cytochrome C, α-chymotrypsin A, and lysozyme, were separated completely with the three novel weak cation exchange chromatography stationary phases. Compared with commercial weak cation exchange chromatography columns, the three kinds of novel weak cation exchange chromatography packings prepared by click chemistry approach have better resolution and selectivity. The mass recovery of more than 97% was obtained for all the tested proteins, and the bioactivity recovery of lysozyme on the prepared column was determined to be 96%. In addition, lysozyme was purified successfully from egg white with the novel weak cation exchange chromatography column by one step. The purity was more than 97% and a high specific activity was achieved to be 81 435 U/mg. The results illustrate the potential of click chemistry for preparing stationary phase for ion-exchange chromatography.

  4. First principles derived, transferable force fields for CO2 adsorption in Na-exchanged cationic zeolites.

    Science.gov (United States)

    Fang, Hanjun; Kamakoti, Preeti; Ravikovitch, Peter I; Aronson, Matthew; Paur, Charanjit; Sholl, David S

    2013-08-21

    The development of accurate force fields is vital for predicting adsorption in porous materials. Previously, we introduced a first principles-based transferable force field for CO2 adsorption in siliceous zeolites (Fang et al., J. Phys. Chem. C, 2012, 116, 10692). In this study, we extend our approach to CO2 adsorption in cationic zeolites which possess more complex structures. Na-exchanged zeolites are chosen for demonstrating the approach. These methods account for several structural complexities including Al distribution, cation positions and cation mobility, all of which are important for predicting adsorption. The simulation results are validated with high-resolution experimental measurements of isotherms and microcalorimetric heats of adsorption on well-characterized materials. The choice of first-principles method has a significant influence on the ability of force fields to accurately describe CO2-zeolite interactions. The PBE-D2 derived force field, which performed well for CO2 adsorption in siliceous zeolites, does not do so for Na-exchanged zeolites; the PBE-D2 method overestimates CO2 adsorption energies on multi-cation sites that are common in cationic zeolites with low Si/Al ratios. In contrast, a force field derived from the DFT/CC method performed well. Agreement was obtained between simulation and experiment not only for LTA-4A on which the force field fitting is based, but for other two common adsorbents, NaX and NaY.

  5. Change Color Effect and Spectral Properties of Gold Nanoparticle-cationic Surfactants System

    Institute of Scientific and Technical Information of China (English)

    JIANG Zhi-liang; PAN Hong-cheng; YUAN Wei-en

    2004-01-01

    The change color effect of gold nanoparticle solutions was studied by means of resonance scattering and absorption spectrometry and scan electron microscopy. The red Au nanoparticles with a size of 10 nm exhibit a resonance absorption peak and a resonance scattering peak all at 525 nm. After some inorganic electrolyte was added to a red Au nanoparticles solution, the color of the solution became blue and the absorbance at 600-700 nm was significantly increased. The ratio of the concentration of monovalent cations, at which the resonance scattering of the system at 525 nm is maximal to that of divalent cations, is in the range of 100 : 1 -100 : 1.8. It is in good agreement with the Schulze-Hardy rule of the coagulation value of electrolyte. After adding some cationic surfactants to the above solution, the color of the solution is in deep blue, with two resonance absorption peaks at 550 and 680 nm, and a greatly enhanced resonance scattering peak at 525 nm.The experiments demonstrate that the stronger the hydrophobicity of the cationic surfactant is, the stronger the change color effect of the Au nanoparticle solution promoted by cationic surfactant is. The change color effect of Au nanoparticle solution is resulted from the increased diameter of Au nanoparticles, and the changes of resonance absorption peak and resonance scattering.

  6. Cationic β-cyclodextrin polymer applied to a dual cyclodextrin polyelectrolyte multilayer system.

    Science.gov (United States)

    Junthip, Jatupol; Tabary, Nicolas; Leclercq, Laurent; Martel, Bernard

    2015-08-01

    A polyelectrolyte multilayer film (PEM) based on cationic and anionic β-cyclodextrin polyelectrolytes was coated onto a textile substrate for future drug delivery purposes. We firstly synthesized a novel cationic β-cyclodextrin polymer (polyEPG-CD) by crosslinking β-cyclodextrin (βCD) with epichlorohydrin (EP) under basic conditions, in the presence of glycidyltrimetrylammonium chloride (GTMAC) as cationizing group. The influence of preparation conditions has been investigated in order to preferably obtain a water soluble fraction whose charge density and molecular weights were optimal for the layer-by-layer (LbL) deposition process. The different cationic cyclodextrin polymers obtained were characterized by FTIR, NMR, colloidal titration, conductimetry, thermogravimetric analysis and size exclusion chromatography. Besides, the counterpart polyelectrolyte was a β-cyclodextrin polymer crosslinked with citric acid, polyCTR-CD, whose synthesis and characterization have been previously reported. Finally we realized the Layer by Layer (LbL) build-up of the PEM coating onto the textile support, using the dip coating method, by alternatively soaking it in cationic polyEPG-CD and anionic polyCTR-CD solutions. This multilayer self-assembly was monitored by SEM, gravimetry and OWLS in function of both polyelectrolytes concentrations and ratios. Solutions parameters such as pH, ionic strenght were also discussed.

  7. Carbamate-linked cationic lipids with different hydrocarbon chains for gene delivery.

    Science.gov (United States)

    Shi, Jia; Yu, Shijun; Zhu, Jie; Zhi, Defu; Zhao, Yinan; Cui, Shaohui; Zhang, Shubiao

    2016-05-01

    A series of carbamate-linked cationic lipids containing saturated or unsaturated hydrocarbon chains and quaternary ammonium head were designed and synthesized. After recrystallization, carbamate-linked cationic lipids with high purity (over 95%) were obtained. The structures of these lipids were proved by IR spectrum, HR-ESI-MS, HPLC, (1)H NMR and (13)C NMR. The liposomes were prepared by using these cationic lipids and neutral lipid DOPE. Particle size and zeta-potential were studied to show that they were suitable for gene transfection. The DNA-bonding ability of C12:0, C14:0 and C18:1 cationic liposomes was much better than others. The results of transfection showed that hydrophobic chains of these lipids have great effects on their transfection activity. The lipids bearing C12:0, C14:0 saturated chains or C18:1 unsaturated chain showed relatively higher transfection efficiency and lower cytotoxicity. So these cationic lipids could be used as non-viral gene carriers for further studies.

  8. Hybrid Perovskite Light-Emitting Diodes Based on Perovskite Nanocrystals with Organic-Inorganic Mixed Cations.

    Science.gov (United States)

    Zhang, Xiaoli; Liu, He; Wang, Weigao; Zhang, Jinbao; Xu, Bing; Karen, Ke Lin; Zheng, Yuanjin; Liu, Sheng; Chen, Shuming; Wang, Kai; Sun, Xiao Wei

    2017-03-07

    Organic-inorganic hybrid perovskite materials with mixed cations have demonstrated tremendous advances in photovoltaics recently, by showing a significant enhancement of power conversion efficiency and improved perovskite stability. Inspired by this development, this study presents the facile synthesis of mixed-cation perovskite nanocrystals based on FA(1-x) Csx PbBr3 (FA = CH(NH2 )2 ). By detailed characterization of their morphological, optical, and physicochemical properties, it is found that the emission property of the perovskite, FA(1-x) Csx PbBr3 , is significantly dependent on the substitution content of the Cs cations in the perovskite composition. These mixed-cation perovskites are employed as light emitters in light-emitting diodes (LEDs). With an optimized composition of FA0.8 Cs0.2 PbBr3 , the LEDs exhibit encouraging performance with a highest reported luminance of 55 005 cd m(-2) and a current efficiency of 10.09 cd A(-1) . This work provides important instructions on the future compositional optimization of mixed-cation perovskite for obtaining high-performance LEDs. The authors believe this work is a new milestone in the development of bright and efficient perovskite LEDs.

  9. Quantitative characterization of non-classic polarization of cations on clay aggregate stability.

    Directory of Open Access Journals (Sweden)

    Feinan Hu

    Full Text Available Soil particle interactions are strongly influenced by the concentration, valence and ion species and the pH of the bulk solution, which will also affect aggregate stability and particle transport. In this study, we investigated clay aggregate stability in the presence of different alkali ions (Li+, Na+, K+, and Cs+ at concentrations from10-5 to 10-1 mol L-1. Strong specific ion effects on clay aggregate stability were observed, and showed the order Cs+>K+>Na+>Li+. We found that it was not the effects of ion size, hydration, and dispersion forces in the cation-surface interactions but strong non-classic polarization of adsorbed cations that resulted in these specific effects. In this study, the non-classic dipole moments of each cation species resulting from the non-classic polarization were estimated. By comparing non-classic dipole moments with classic values, the observed dipole moments of adsorbed cations were up to 104 times larger than the classic values for the same cation. The observed non-classic dipole moments sharply increased with decreasing electrolyte concentration. We conclude that strong non-classic polarization could significantly suppress the thickness of the diffuse layer, thereby weakening the electric field near the clay surface and resulting in improved clay aggregate stability. Even though we only demonstrated specific ion effects on aggregate stability with several alkali ions, our results indicate that these effects could be universally important in soil aggregate stability.

  10. Cationic Liposomes Modified with Polyallylamine as a Gene Carrier: Preparation, Characterization and Transfection Efficiency Evaluation

    Directory of Open Access Journals (Sweden)

    Reza Kazemi Oskuee

    2016-12-01

    Full Text Available Purpose: Cationic polymers and cationic liposomes have shown to be effective non-viral gene delivery vectors. In this study, we tried to improve the transfection efficiency by employing the advantages of both. Methods: For this purpose, modified polyallylamines (PAAs were synthesized. These modifications were done through the reaction of PAA (15 KDa with acrylate and 6-bromoalkanoic acid derivatives. Liposomes comprising of these cationic polymers and cationic lipid were prepared and extruded through polycarbonate filters to obtain desired size. Liposome-DNA nanocomplexes were prepared in three carrier to plasmid (C/P ratios. Size, zeta potential and DNA condensation ability of each complex were characterized separately and finally transfection efficiency and cytotoxicity of prepared vectors were evaluated in Neuro2A cell line. Results: The results showed that mean particle size of all these nanocomplexes was lower than 266 nm with surface charge of 22.0 to 33.9 mV. Almost the same condensation pattern was observed in all vectors and complete condensation was occurred at C/P ratio of 1.5. The lipoplexes containing modified PAA 15 kDa with 10% hexyl acrylate showed the highest transfection efficacy and lowest cytotoxicity in C/P ratio of 0.5. Conclusion: In some cases nanocomplexes consisting of cationic liposome and modified PAA showed better transfection activity and lower cytotoxicity compared to PAA.

  11. Association Mechanisms of Unsaturated C2 Hydrocarbons with Their Cations: Acetylene and Ethylene

    Science.gov (United States)

    Bera, Partha P.; Head-Gordon, Martin; Lee, Timothy J.

    2013-01-01

    The ion-molecule association mechanism of acetylene and ethylene with their cations is investigated by ab initio quantum chemical methods to understand the structures, association energies, and the vibrational and electronic spectra of the products. Stable puckered cyclic isomers are found as the result of first forming less stable linear and bridge isomers. The puckered cyclic complexes are calculated to be strongly bound, by 87, 35 and 56 kcal/mol for acetylene-acetylene cation, ethylene-ethylene cation and acetylene-ethylene cation, respectively. These stable complexes may be intermediates that participate in further association reactions. There are no association barriers, and no significant inter-conversion barriers, so the initial linear and bridge encounter complexes are unlikely to be observable. However, the energy gap between the bridged and cyclic puckered isomers greatly differs from complex to complex: it is 44 kcal/mol in C4H4 +, but only 6 kcal/mol in C4H8 +. The accurate CCSD(T) calculations summarized above are also compared against less computationally expensive MP2 and density functional theory (DFT) calculations for structures, relative energies, and vibrational spectra. Calculated vibrational spectra are compared against available experiments for cyclobutadiene cation. Electronic spectra are also calculated using time-dependent DFT.

  12. Adsorption of mixed cationic-nonionic surfactant and its effect on bentonite structure

    Institute of Scientific and Technical Information of China (English)

    Yaxin Zhang; Yan Zhao; Yong Zhu; Huayong Wu; Hongtao Wang; Wenjing Lu

    2012-01-01

    The adsorption of cationic-nordonic mixed surfactant onto bentonite and its effect on bentonite structure were investigated.The objective was to improve the understanding of surfactant behavior on clay mineral for its possible use in remediation technologies of soil and groundwater contaminated by toxic organic compounds.The cationic surfactant used was hexadecylpyridinium bromide(HDPB),and the nonionic suffactant was Triton X-100(TX100).Adsorption of TX100 was enhanced significantly by the addition of HDPB,but this enhancement decreased with an increase in the fraction of the cationic surfactant.Part of HDPB was replaced by TX100 which decreased the adsorption of HDPB.However,the total adsorbed amount of the mixed surfactant was still increased substantially,indicating the synergistic effect between the cationic and nonionic surfactants.The surfactant-modified bentonite was characterized by Brunauer-Emmett-Teller specific surface area measurement,Fourier transform infrared spectroscopy,and thermogravimetric-derivative thermogravimetric/differential thermal analyses.Surfactant intercalation was found to decrease the bentonite specific surface area,pore volume,and surface roughness and irregularities,as calculated by nitrogen adsorption-desorption isotherms.The co-adsorption of the cationic and nonionic surfactants increased the ordering conformation of the adsorbed surfactants on bentonite,but decreased the thermal stability of the organobentonite system.

  13. Selective Antimicrobial Activities and Action Mechanism of Micelles Self-Assembled by Cationic Oligomeric Surfactants.

    Science.gov (United States)

    Zhou, Chengcheng; Wang, Fengyan; Chen, Hui; Li, Meng; Qiao, Fulin; Liu, Zhang; Hou, Yanbo; Wu, Chunxian; Fan, Yaxun; Liu, Libing; Wang, Shu; Wang, Yilin

    2016-02-17

    This work reports that cationic micelles formed by cationic trimeric, tetrameric, and hexameric surfactants bearing amide moieties in spacers can efficiently kill Gram-negative E. coli with a very low minimum inhibitory concentration (1.70-0.93 μM), and do not cause obvious toxicity to mammalian cells at the concentrations used. With the increase of the oligomerization degree, the antibacterial activity of the oligomeric surfactants increases, i.e., hexameric surfactant > tetrameric surfactant > trimeric surfactant. Isothermal titration microcalorimetry, scanning electron microscopy, and zeta potential results reveal that the cationic micelles interact with the cell membrane of E. coli through two processes. First, the integrity of outer membrane of E. coli is disrupted by the electrostatic interaction of the cationic ammonium groups of the surfactants with anionic groups of E. coli, resulting in loss of the barrier function of the outer membrane. The inner membrane then is disintegrated by the hydrophobic interaction of the surfactant hydrocarbon chains with the hydrophobic domains of the inner membrane, leading to the cytoplast leakage. The formation of micelles of these cationic oligomeric surfactants at very low concentration enables more efficient interaction with bacterial cell membrane, which endows the oligomeric surfactants with high antibacterial activity.

  14. Size of the Organic Cation Tunes the Band Gap of Colloidal Organolead Bromide Perovskite Nanocrystals.

    Science.gov (United States)

    Mittal, Mona; Jana, Atanu; Sarkar, Sagar; Mahadevan, Priya; Sapra, Sameer

    2016-08-18

    A few approaches have been employed to tune the band gap of colloidal organic-inorganic trihalide perovskites (OTPs) nanocrystals by changing the halide anion. However, to date, there is no report of electronic structure tuning of perovskite NCs upon changing the organic cation. We report here, for the first time, the room temperature colloidal synthesis of (EA)x(MA)1-xPbBr3 nanocrystals (NCs) (where, x varies between 0 and 1) to tune the band gap of hybrid organic-inorganic lead perovskite NCs from 2.38 to 2.94 eV by varying the ratio of ethylammonium (EA) and methylammonium (MA) cations. The tuning of band gap is confirmed by electronic structure calculations within density functional theory, which explains the increase in the band gap upon going toward larger "A" site cations in APbBr3 NCs. The photoluminescence quantum yield (PLQY) of these NCs lies between 5% to 85% and the average lifetime falls in the range 1.4 to 215 ns. A mixture of MA cations and its higher analog EA cations provide a versatile tool to tune the structural as well as optoelectronic properties of perovskite NCs.

  15. Stilbene dimer radical cations in the radiolyses of stilbenes and 1,2,3,4-tetraphenylcyclobutanes

    Energy Technology Data Exchange (ETDEWEB)

    Tojo, Sachiko; Morishima, Kazuhiro; Ishida, Akito; Majima, Tetsuro; Takamuku, Setsuo [Osaka Univ., Ibaraki (Japan). Inst. of Scientific and Industrial Research

    1995-03-01

    The reaction of the stilbene radical cation formed by pulse radiolysis or {gamma}-radiolyses is explained based on neutralization as well as the formation of a {pi}-type stilbene dimer radical cation ({pi}-St{sub 2}{sup +{center_dot}}), converting to the {sigma}-type St{sub 2}{sup +{center_dot}} ({sigma}-St{sub 2}{sup +{center_dot}}). The r-1, c-2, t-3, t-4-tetraphenylcyclobutane radical cation generated in a rigid matrix at 77 K which converted to {sigma}-St{sub 2}{sup +{center_dot}} upon warming. Both r-1, c-2, t-3, t-4- and r-1, t-2, c-3, t-4-tetraphenylcyclobutane radical cations underwent photochemical cycloreversion to {pi}-St{sub 2}{sup +{center_dot}} upon irradiation at wavelengths longer than 390 nm at 77 K, and converted to {sigma}-St{sub 2}{sup +{center_dot}} upon warming. It is suggested that {pi}-St{sub 2}{sup +{center_dot}} has overlapping arrangements of {pi}-electrons, while {sigma}-St{sub 2}{sup +{center_dot}} has radical and cation centers on the 1- and 4-positions of the C{sub 4} linkage. (author).

  16. Cationic Redistribution at Epitaxial Interfaces in Superconducting Two-Dimensionally Doped Lanthanum Cuprate Films.

    Science.gov (United States)

    Baiutti, Federico; Gregori, Giuliano; Wang, Yi; Suyolcu, Y Eren; Cristiani, Georg; van Aken, Peter A; Maier, Joachim; Logvenov, Gennady

    2016-10-12

    The exploration of interface effects in complex oxide heterostructures has led to the discovery of novel intriguing phenomena in recent years and has opened the path toward the precise tuning of material properties at the nanoscale. One recent example is space-charge superconductivity. Among the complex range of effects which may arise from phase interaction, a crucial role is played by cationic intermixing, which defines the final chemical composition of the interface. In this work, we performed a systematic study on the local cationic redistribution of two-dimensionally doped lanthanum cuprate films grown by oxide molecular beam epitaxy, in which single LaO layers in the epitaxial crystal structure were substituted by layers of differently sized and charged dopants (Ca, Sr, Ba, and Dy). In such a model system, in which the dopant undergoes an asymmetric redistribution across the interface, the evolution of the cationic concentration profile can be effectively tracked by means of atomically resolved imaging and spectroscopic methods. This allowed for the investigation of the impact of the dopant chemistry (ionic size and charge) and of the growth conditions (temperature) on the final superconducting and structural properties. A qualitative model for interface cationic intermixing, based on thermodynamic considerations, is proposed. This work highlights the key role which cationic redistribution may have in the definition of the final interface properties and represents a further step forward the realization of heterostructures with improved quality.

  17. Effect of alkali-treated lipopolysaccharide on the intracellular cations of human erythrocytes.

    Science.gov (United States)

    Warren, J R; Kowalski, M M; Wallas, C H

    1977-08-01

    The adsorption to human erythrocytes of Escherichia coli lipopolysaccharide treated by mild alkaline hydrolysis (h-LPS) stimulated an increase in the intracellular Na+ concentration and a decrease in the intracellular K+ concentration of the erythrocytes. Erythrocytes treated by h-LPS remained responsive to the membrane adenosine triphosphatase inhibitors ouabain and ethacrynic acid, indicating that hLPS did not alter erythrocyte cations be depleting energy intermediates or uncoupling energy metabolism from active cation transport. The h-LPS-treated erythrocytes became non-agglutinable by the lectin concanavalin A prior to the development of changes in intracellular cations. In addition, h-LPS-treated erythrocytes demonstrated a three-fold greater cation response to ethacrynic acid than the untreated erythrocytes; this greater response was probably due to local membrane effects by h-LPS on the ethacrynic acid-sensitive adenosine triphosphatase. It is suggested that the h-LPS-induced alteration of erythrocyte cation content was secondary to an increase in ion permeability localized to the concanavalin A receptor regions of the erythrocyte membrane, possibly combined with indirect effects of membrane-bound h-LPS on ethacrynic acid-sensitive adenosine triphosphatase.

  18. Visible photodissociation spectroscopy of PAH cations and derivatives in the PIRENEA experiment

    CERN Document Server

    Useli-Bacchitta, F; Mulas, G; Malloci, G; Toublanc, D; Joblin, C; 10.1016/j.chemphys.2010.03.012

    2010-01-01

    The electronic spectra of gas-phase cationic polycyclic aromatic hydrocarbons (PAHs), trapped in the Fourier Transform Ion Cyclotron Resonance cell of the PIRENEA experiment, have been measured by multiphoton dissociation spectroscopy in the 430-480 nm spectral range using the radiation of a mid-band optical parametric oscillator laser. We present here the spectra recorded for different species of increasing size, namely the pyrene cation (C16H10+), the 1-methylpyrene cation (CH3-C16H9+), the coronene cation (C24H12+), and its dehydrogenated derivative C24H10+. The experimental results are interpreted with the help of time-dependent density functional theory calculations and analysed using spectral information on the same species obtained from matrix isolation spectroscopy data. A kinetic Monte Carlo code has also been used, in the case of pyrene and coronene cations, to estimate the absorption cross-sections of the measured electronic transitions. Gas-phase spectra of highly reactive species such as dehydrog...

  19. DFT and MP2 study of the interaction between corannulene and alkali cations.

    Science.gov (United States)

    Rellán-Piñeiro, Marcos; Rodríguez-Otero, Jesús; Cabaleiro-Lago, Enrique M; Josa, Daniela

    2013-05-01

    Corannulene is an unsaturated hydrocarbon composed of fused rings, with one central five-membered ring and five peripheral six-membered rings. Its structure can be considered as a portion of C60. Corannulene is a curved π surface, but unlike C60, it has two accessible different faces: one concave (inside) and one convex (outside). In this work, computational modeling of the binding between alkali metal cations (Li(+), Na(+), and K(+)) and corannulene has been performed at the DFT and MP2 levels. Different corannulene···M(+) complexes have been studied and the transition states interconnecting local minima were located. The alkali cations can be bound to a five or six membered ring in both faces. At the DFT level, binding to the convex face (outside) is favored relative to the concave face for the three alkali cations studied, as it was previously published. This out preference was found to decrease as cation size increases. At the MP2 level, although a similar trend is found, some different conclusions related to the in/out preference were obtained. According to our results, migration of cations can take place on the convex or on the concave face. Also, there are two ways to transform a concave complex in a convex complex: migration across the edge of corannulene and bowl-to-bowl inversion.

  20. Step-by-step deposition of synthetic dopamine-eumelanin and metal cations.

    Science.gov (United States)

    Ball, Vincent; Bour, Jérôme; Michel, Marc

    2013-09-01

    The photoprotection of skin depends mostly on a balance between two natural pigments: the black-brown eumelanin and the yellow-reddish pheomelanin. These pigments as well as their counterpart in the central nervous system, neuromelanin, interact strongly with metal cations like Fe(3+). In the mussel foot proteins, the coordination between catechol groups and these ions is also responsible for the strong hardness the mussel's cuticle. These examples are suggestive that coatings and materials can be made based on such materials, for instance, synthetic eumelanin colloids and metal cations. Herein, we demonstrate that films made from synthetic dopamine-eumelanin colloids and metal cations can be deposited on surfaces in a step-by-step manner. As typical metal cations, we used Cu(2+), Fe(3+), and La(3+) which are known to interact with eumelanins. In all cases, step-by-step deposition is only possible in the absence of water rinse between two deposition steps. It was found that trivalent cations allow for a faster increase in film deposition than Cu(2+). Complementary in PDADMAC-(eumelanin-Fe(3+))m films, iron III was found not to be reduced.

  1. Understanding the impact of the central atom on the ionic liquid behavior: Phosphonium vs ammonium cations

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Pedro J.; Ventura, Sónia P. M.; Batista, Marta L. S.; Schröder, Bernd; Coutinho, João A. P., E-mail: jcoutinho@ua.pt [CICECO, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Gonçalves, Fernando [Departamento de Biologia e CESAM (Centro de Estudos do Ambiente e do Mar), Universidade de Aveiro, 3810-193 Aveiro (Portugal); Esperança, José [Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2780-901 Oeiras (Portugal); Mutelet, Fabrice [Laboratoire Réactions et Génie des Procédés, CNRS (UPR3349), Nancy-Université, 1 rue Grandville, BP 20451 54001 Nancy (France)

    2014-02-14

    The influence of the cation's central atom in the behavior of pairs of ammonium- and phosphonium-based ionic liquids was investigated through the measurement of densities, viscosities, melting temperatures, activity coefficients at infinite dilution, refractive indices, and toxicity against Vibrio fischeri. All the properties investigated are affected by the cation's central atom nature, with ammonium-based ionic liquids presenting higher densities, viscosities, melting temperatures, and enthalpies. Activity coefficients at infinite dilution show the ammonium-based ionic liquids to present slightly higher infinite dilution activity coefficients for non-polar solvents, becoming slightly lower for polar solvents, suggesting that the ammonium-based ionic liquids present somewhat higher polarities. In good agreement these compounds present lower toxicities than the phosphonium congeners. To explain this behavior quantum chemical gas phase DFT calculations were performed on isolated ion pairs at the BP-TZVP level of theory. Electronic density results were used to derive electrostatic potentials of the identified minimum conformers. Electrostatic potential-derived CHelpG and Natural Population Analysis charges show the P atom of the tetraalkylphosphonium-based ionic liquids cation to be more positively charged than the N atom in the tetraalkylammonium-based analogous IL cation, and a noticeable charge delocalization occurring in the tetraalkylammonium cation, when compared with the respective phosphonium congener. It is argued that this charge delocalization is responsible for the enhanced polarity observed on the ammonium based ionic liquids explaining the changes in the thermophysical properties observed.

  2. High DNA-Binding Affinity and Gene-Transfection Efficacy of Bioreducible Cationic Nanomicelles with a Fluorinated Core.

    Science.gov (United States)

    Wang, Long-Hai; Wu, De-Cheng; Xu, Hang-Xun; You, Ye-Zi

    2016-01-11

    During the last two decades, cationic polymers have become one of the most promising synthetic vectors for gene transfection. However, the weak interactions formed between DNA and cationic polymers result in low transfection efficacy. Furthermore, the polyplexes formed between cationic polymers and DNA generally exhibit poor stability and toxicity because of the large excess of cationic polymer typically required for complete DNA condensation. Herein, we report the preparation of a novel class of bioreducible cationic nanomicelles by the use of disulfide bonds to connect the cationic shell to the fluorocarbon core. These bioreducible nanomicelles form strong interactions with DNA and completely condense DNA at an N/P ratio of 1. The resulting nanomicelle/DNA polyplexes exhibited high biocompatibility and performed very effectively as a gene-delivery system.

  3. Tris(triazole) tripodal receptors as selective probes for citrate anion recognition and multichannel transition and heavy metal cation sensing.

    Science.gov (United States)

    González, María del Carmen; Otón, Francisco; Espinosa, Arturo; Tárraga, Alberto; Molina, Pedro

    2015-02-01

    The three-armed pyrenyl-triazole receptor 1 behaves as a highly selective fluorescent molecular sensor for citrate anions over similar carboxylates such as malate or tartrate. In addition, this receptor senses Cu(2+) cations through absorption and emission channels even in the presence of Hg(2+) metal cations. The related three-armed ferrocenyl-triazole receptor 2 behaves as a highly selective dual (redox and chromogenic) chemosensor molecule for Pb(2+) metal cations.

  4. Semi-quantitative determination of cationic surfactants in aqueous solutions using gold nanoparticles as reporter probes.

    Science.gov (United States)

    Kuong, Chi-Lap; Chen, Wei-Yu; Chen, Yu-Chie

    2007-03-01

    Concentrations of cationic surfactants in aqueous solutions have been estimated on the basis of changes in the color of gold nanoparticles, used as reporter probes. We have shown that the colors of gold nanoparticles with anionic protective groups on their surfaces shift from red to indigo/purple and then back to red in a range of cationic surfactant solutions in which concentrations vary from very low to above the theoretical CMCs. The color changes occur near the theoretical CMCs, presumably because the presence of surfactant micelles in the solution prevents the gold nanoparticles from aggregating. We have used gold nanoparticles as reporter probes to determine the concentrations of cationic surfactants in products such as hair conditioners, which often contain large amounts of alkyltrimethylammonium halides. Although this approach can only provide an estimate, it can be performed simply by addition of a given amount of gold nanoparticles to a series of diluted solutions, without the need for instruments or labor-intensive procedures.

  5. Molecular mechanics-valence bond method for planar conjugated hydrocarbon cations.

    Science.gov (United States)

    Hall, Katherine F; Tokmachev, Andrei M; Bearpark, Michael J; Boggio-Pasqua, Martial; Robb, Michael A

    2007-10-07

    We present an extension of the molecular mechanics-valence bond (MMVB) hybrid method to study ground and excited states of planar conjugated hydrocarbon cations. Currently, accurate excited state calculations on these systems are limited to expensive ab initio studies of smaller systems: up to 15 active electrons in 16 pi orbitals with complete active space self-consistent field (CASSCF) theory using high symmetry. The new MMVB extension provides a faster, cheaper treatment to investigate larger cation systems with more than 24 active orbitals. Extension requires both new matrix elements and new parameters: In this paper we present both, for the limited planar case. The scheme is tested for the planar radical cations of benzene, naphthalene, anthracene, and phenanthrene. Calculated MMVB relative energies are in good agreement with CASSCF results for equilibrium geometries on the ground and first excited states, and conical intersections.

  6. Biosorption of silver cations onto Lactococcus lactis and Lactobacillus casei isolated from dairy products

    Science.gov (United States)

    Milanowski, Maciej; Pomastowski, Paweł; Railean-Plugaru, Viorica; Rafińska, Katarzyna; Ligor, Tomasz; Buszewski, Bogusław

    2017-01-01

    The current work deals with the phenomenon of silver cations uptake by two kinds of bacteria isolated from dairy products. The mechanism of sorption of silver cations by Lactococcus lactis and Lactobacillus casei bacteria was investigated. Inductively coupled plasma–mass spectrometry (ICP-MS) was used for determination of silver concentration sorbed by bacteria. Analysis of charge distribution was conducted by diffraction light scattering method. Changes in the ultrastructure of Lactococcus lactis and Lactobacillus casei cells after treatment with silver cations were investigated using transmission electron microscopy observation. Molecular spectroscopy methods, namely Fourier transform-infrared spectroscopy (FT-IR) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) were employed for description of the sorption mechanism. Moreover, an analysis of volatile organic compounds (VOCs) extracted from bacterial cells was performed. PMID:28362838

  7. Cation-π interaction of alkali metal ions with C24 fullerene: a DFT study.

    Science.gov (United States)

    Moradi, Morteza; Peyghan, Ali Ahmadi; Bagheri, Zargham; Kamfiroozi, Mohammad

    2012-08-01

    Using first principle calculations, we investigated cation-π interactions between alkali cations (Li(+), Na(+), and K(+)) and pristine C(24) or doped fullerenes of BC(23), and NC(23). The most suitable adsorption site is found to be atop the center of a six-membered ring of the exterior surface of C(24) molecule. Interaction energies of these cations decreased in the order: Li(+) > Na(+) > K(+), with values of -31.82, -22.36, and -15.68 kcal mol(-1), respectively. It was shown that the interaction energies are increased and decreased by impurity doping of B and N atoms in adjacent wall of adsorption site, depending on electron donating or receptivity of the doping atoms.

  8. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity

    Directory of Open Access Journals (Sweden)

    Johannes Ranke

    2009-03-01

    Full Text Available The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities.

  9. Biodistribution of rhodamine B fluorescence-labeled cationic nanoparticles in rats

    DEFF Research Database (Denmark)

    Knudsen, K. B.; Northeved, H.; Gjetting, Torben;

    2014-01-01

    were used. The animals were randomly allocated to five groups receiving either cationic micelles or cationic liposomes by single intravenous (IV) administration at a dose of 100 mg/kg bodyweight by single intracerebroventricular (ICV) injection at a dose of 50 μg or no treatment. ICV administration......We investigated the biodistribution following the administration of nanosized (about 50 and 90 nm) cationic (ζ: +30 and +50 mV) micelles and liposomes intended for drug delivery. The particles were stable and well characterized with respect to size and ζ potential. Ten 5- to 6-week-old male rats...... was used to study local distribution in the brain and IV administration to study the systemic distribution of the particles. For both types of particles, ICV administration showed distribution in all ventricles in the brain while IV delivery displayed distribution to the major organs liver, spleen, kidney...

  10. Structural Isomerization of the Gas Phase 2-NORBORNYL Cation Revealed with Infrared Spectroscopy and Computational Chemistry

    Science.gov (United States)

    Mauney, Daniel; Mosley, Jonathan; Duncan, Michael A.

    2014-06-01

    The non-classical structure of the 2-norborny cation (C_7H11+) which was at the center of "the most heated chemical controversy of our time" has been observed in the condensed phase and recently using X-ray crystallography. However, no gas phase vibrational spectrum has been collected. The C_7H11+ cation is produced via H_3+ protonation of norbornene by pulsed discharge in a supersonic expansion of H_2/Ar. Ions are mass-selected and probed using infrared photodissociation spectroscopy. Due to high exothermicity, protonation via H_3+ leads to a structural isomerization to the global minimum structure 1,3-dimethylcyclopentenyl (DMCP+). Experiments are currently being conducted to find softer protonation techniques that could lead to the authentic 2-norbornyl cation. Schleyer,P.v.R. et. al.; Stable Carbocation Chemistry, John Wiley & Sons,Inc.; New York, 1997, Chapter 2

  11. The sequence to hydrogenate coronene cations: A journey guided by magic numbers

    CERN Document Server

    Cazaux, Stéphanie; Rougeau, Nathalie; Reitsma, Geert; Hoekstra, Ronnie; Teillet-Billy, Dominique; Morisset, Sabine; Spaans, Marco; Schlathölter, Thomas

    2016-01-01

    The understanding of hydrogen attachment to carbonaceous surfaces is essential to a wide variety of research fields and technologies such as hydrogen storage for transportation, precise localization of hydrogen in electronic devices and the formation of cosmic H2. For coronene cations as prototypical Polycyclic Aromatic Hydrocarbon (PAH) molecules, the existence of magic numbers upon hydrogenation was uncovered experimentally. Quantum chemistry calculations show that hydrogenation follows a site-specific sequence leading to the appearance of cations having 5, 11, or 17 hydrogen atoms attached, exactly the magic numbers found in the experiments. For these closed-shell cations, further hydrogenation requires appreciable structural changes associated with a high transition barrier. Controlling specific hydrogenation pathways would provide the possibility to tune the location of hydrogen attachment and the stability of the system. The sequence to hydrogenate PAHs, leading to PAHs with magic numbers of H atoms att...

  12. The Formalism and Language Tools for Semantics Specification of Software Libraries

    Directory of Open Access Journals (Sweden)

    V. M. Itsykson

    2016-01-01

    Full Text Available The paper is dedicated to the specification of the structure and the behaviour of soft-ware libraries. It describes the existing problems of libraries specifications. A brief overview of the research field concerned with formalizing the specification of libraries and library functions is presented. The requirements imposed on the formalism designed are established; the formalism based on these requirements allows specifying all the properties of the libraries needed for automation of several classes of problems: defects detection in the software, migration of applications into a new environment, gen-eration of software documentation. The requirements on the language tools based on the developed formalism are proposed. The conclusion defines potential directions for further research.

  13. Electrochemical Behavior of Steel Bar in Electrolytes:Influence ofpH Value and Cations

    Institute of Scientific and Technical Information of China (English)

    PU Qi; JIANG Linhua; CHU Hongqiang; XU Jinxia; XU Yi

    2011-01-01

    Steel bar corrosion on electrolytes and the influence of cation were investigated.Three electrolytes of Ca(OH)2,NaOH and KOH with pH levels of 12.5,11.5,10.5,9.5,8.5 were prepared,meanwhile,the methods of free corrosion potential and electrochemical impedance spectra (EIS) were used to evaluate the influence of cations on the depassivation of the steel bar in electrolytes.The experimental results indicate that the initial corrosion pH value of the steel bar is influenced by the cation in electrolyte and the influence ofK+ in electrolyte is the most remarkable,followed by Na+ and Ca2+.The initial corrosion pH values are 10.5 in KOH electrolyte,9.5 in NaOH electrolyte and lower than 8.5 in Ca(OH)2 electrolyte.

  14. Understanding the salinity effect on cationic polymers in inducing flocculation of the microalga Neochloris oleoabundans.

    Science.gov (United States)

    't Lam, G P; Giraldo, J B; Vermuë, M H; Olivieri, G; Eppink, M H M; Wijffels, R H

    2016-05-10

    A mechanistic study was performed to evaluate the effect of salinity on cationic polymeric flocculants, that are used for the harvesting of microalgae. The polyacrylamide Synthofloc 5080H and the polysaccharide Chitosan were employed for the flocculation of Neochloris oleoabundans. In seawater conditions, a maximum biomass recovery of 66% was obtained with a dosage of 90mg/L Chitosan. This recovery was approximately 25% lower compared to Synthofloc 5080H reaching recoveries greater than 90% with dosages of 30mg/L. Although different recoveries were obtained with both flocculants, the polymers exhibit a similar apparent polymer length, as was evaluated from viscosity measurements. While both flocculants exhibit similar polymer lengths in increasing salinity, the zeta potential differs. This indicates that polymeric charge dominates flocculation. With increased salinity, the effectivity of cationic polymeric flocculants decreases due to a reduction in cationic charge. This mechanism was confirmed through a SEM analysis and additional experiments using flocculants with various charge densities.

  15. Current scenario of peptide-based drugs: the key roles of cationic antitumor and antiviral peptides

    Directory of Open Access Journals (Sweden)

    Kelly eMulder

    2013-10-01

    Full Text Available Cationic antimicrobial peptides (AMPs and host defense peptides (HDPs show vast potential as peptide-based drugs. Great effort has been made in order to exploit their mechanisms of action, aiming to identify their targets as well as to enhance their activity and bioavailability. In this review, we will focus on both naturally occurring and designed antiviral and antitumor cationic peptides, including those here called promiscuous, in which multiple targets are associated with a single peptide structure. Emphasis will be given to their bio-chemical features, selectivity against extra targets and molecular mechanisms. Peptides which possess antitumor activity against different cancer cell lines will be discussed, as well as peptides which inhibit virus replication, focusing on their applications for human health, animal health and agriculture, and their potential as new therapeutic drugs. Moreover, the development of production and nano-delivery systems for both classes of cationic peptides and perspectives on improving them will be considered.

  16. Study of cation distribution of spinel zinc nano-ferrite by X-ray

    Science.gov (United States)

    Najafi Birgani, Azadeh; Niyaifar, Mohammad; Hasanpour, Ahmad

    2015-01-01

    A set of zinc ferrite samples with ZnFe2O4 chemical composition were synthesized in 400, 500, and 1100 °C using conventional solid state synthesis method. The X-ray diffraction pattern of all the three samples was studied at room temperature. This diffraction pattern confirmed the existence of a single-phase cubic spinel structure with lattice parameters of 8.451, 8.448, and 8.437 Å, respectively. Oxygen position and cation distribution of the samples between the tetrahedral site, A and the octahedral site, B were examined using R-Factor method. The results showed that cation distribution of zinc ferrite samples changes from a normal spinel mode into a mixed spinel mode with the decrease of particle size. Moreover, the ratio of zinc divalent cations migrating from the tetrahedral site to the octahedral site was calculated.

  17. Synthesis and Characterization of Zirconia Nanocrystallites by Cationic Surfactant and Anionic Surfactant

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Study on nanomaterials has attracted great interests in recent years. In this article,zirconia nanocrystallites of different structures have been successfully synthesized via hydrothermal methods with cationic surfactant (CTAB) and anionic surfactant (SDS), respectively. Differential Scanning Calorimeter (DSC-TG), X-ray Diffractometer (XRD), Transmission Electron Microscope (TEM), Ultraviolet-Visible (UV-vis) and N2 adsorption-desorption analyses are used for their structure characteristics. The results show that the cationic surfactant has a distinctive direction effect on the formation of zirconia nanocrystallites, while the anionic surfactant has a self-assembly synergistic effect on them. The sample synthesized with the cationic surfactant presents good dispersion with the main phase of tetragonal zirconia, and the average nanocryst al size is around 15nm after calcination at 500 ℃. While the sample synthesized with the anionic surfactant exhibits a worm-like mesoporous structure with pure tetragonal phase after calcination at 500 ℃ and with good thermal stability.

  18. Microscopic approach for the identification of cationic membrane fouling during cheddar cheese whey electroacidification.

    Science.gov (United States)

    Lin Teng Shee, F; Angers, P; Bazinet, L

    2008-06-15

    This is the first time that fouling of cation-exchange membranes during cheddar cheese whey electroacidification with bipolar membranes is reported. A mineral fouling was observed only on the cationic membrane side in contact with the base. The deposit was identified as magnesium hydroxide and this fouling was more important on the cation-exchange membrane situated close to the cathode. Little deposit was formed after six electroacidification runs, but on long time, the buildup of fouling film would lead after many electroacidifications to an important decrease of the system efficiency. Since, fouling of permselective membranes represents one of the major issues in electrodialytic processes, this result will be the basis for the determination of cleaning conditions allowing the prevention of such a fouling.

  19. The Metal Cation Chelating Capacity of Astaxanthin. Does This Have Any Influence on Antiradical Activity?

    Directory of Open Access Journals (Sweden)

    Ana Martínez

    2012-01-01

    Full Text Available In this Density Functional Theory study, it became apparent that astaxanthin (ASTA may form metal ion complexes with metal cations such as Ca+2, Cu+2, Pb+2, Zn+2, Cd+2 and Hg+2. The presence of metal cations induces changes in the maximum absorption bands which are red shifted in all cases. Therefore, in the case of compounds where metal ions are interacting with ASTA, they are redder in color. Moreover, the antiradical capacity of some ASTA-metal cationic complexes was studied by assessing their vertical ionization energy and vertical electron affinity, reaching the conclusion that metal complexes are slightly better electron donors and better electron acceptors than ASTA.

  20. Theoretical study of second-order hyperpolarizability for nitrogen radical cation

    Science.gov (United States)

    Tarazkar, Maryam; Romanov, Dmitri A.; Levis, Robert J.

    2015-05-01

    We report calculations of the static and dynamic hyperpolarizabilities of the nitrogen radical cation in doublet state. The electronic contributions were computed analytically using density functional theory and multi-configurational self-consistent field method with extended basis sets for non-resonant excitation. The open-shell electronic system of nitrogen radical cation provides negative second-order optical nonlinearity, suggesting that the hyperpolarizability coefficient, {{γ }(2)}, in the non-resonant regime is mainly composed of combinations of virtual one-photon transitions rather than two-photon transitions. The second-order optical properties of nitrogen radical cation have been calculated as a function of bond length starting with the neutral molecular geometry (S0 minimum) and stretching the N-N triple bond, reaching the ionic D0 relaxed geometry all the way toward dissociation limit, to investigate the effect of internuclear bond distance on second-order hyperpolarizability.

  1. A study on cations and color removal from thin sugar juice by modified sugar beet pulp.

    Science.gov (United States)

    Arslanoglu, Hasan; Tumen, Fikret

    2012-06-01

    This article describes the use of citric acid modified sugar beet pulp as new ion-exchanger sorbent for the removal of metal cations and colorants from thin juice. The results of batch adsorption runs concerning the effects of contact time, material dosage, temperature and pH drop were presented and discussed. Experimental data on the removal of metal cations showed that the sorption process was rapid and reached equilibrium in 60 min. Modified material in acidic form caused to a significant pH drop in thin juice, which could result with sucrose inversion. Uptake of metal cations increased with temperature whereas that of color decreased. Neutralised type modified product gave more satisfying results. After six successive contacts, 49.7%, 37.5% and 43.7% removals for Ca-Mg, K and color, respectively, were obtained by using neutralised form of modified sugar beet pulp.

  2. Hydrophobic Encapsulated Phosphonium Salts-Synthesis of Weakly Coordinating Cations and their Application in Wittig Reactions.

    Science.gov (United States)

    Moritz, Ralf; Wagner, Manfred; Schollmeyer, Dieter; Baumgarten, Martin; Müllen, Klaus

    2015-06-15

    Large and rigid tetraarylphosphonium tetrafluoroborate salts have been synthesized representing weakly coordinating cations with diameters of several nanometers. Divergent dendritic growth by means of thermal Diels-Alder cycloaddition was employed for the construction of the hydrophobic polyphenylene framework up to the third generation. X-ray crystal structure analysis of first-generation phosphonium tetrafluoroborate supported the rigidity of the non-collapsible shell around the phosphorus center and gave insight into solid-state packing and cation-anion distances. Copper(I)-catalyzed azide-alkyne ligation served as reliable method for the preparation of a first-generation triazolylphenyl hybrid phosphonium cation under mild reaction conditions. Furthermore, from the synthesis of triarylbenzylphosphonium bromides, Wittig precursors with unprecedented bulky substituents in the α-position were accessible. Employment of these precursors under Wittig conditions by treatment with base and subsequent reaction with aldehydes preferentially provided (Z)-olefins with bulky polyphenylene substituents.

  3. Vibrational studies of benzene, pyridine, pyridine-N-oxide and their cations.

    Science.gov (United States)

    Kumar, M; Srivastava, Mayuri; Yadav, R A

    2013-07-01

    IR and Raman spectra of pyridine and pyridine-N-oxide have been recorded and analyzed. The optimized molecular geometries, APT charges and vibrational characteristics for benzene, pyridine, pyridine-N-oxide and their cations have been computed using DFT method. Due to attachment of O atom at N site or removal of electron all the modes are affected in magnitudes. However, significant changes are noticed in their IR intensities, Raman activities and depolarization ratios of the Raman bands in going from pyridine to its N-oxide or in going from neutrals to their cations. It is interesting to note that in going from benzene to benzene cation charge redistribution takes place to reduce the symmetry from D6h to D2h. The calculated frequencies have been correlated with the experimental frequencies for the pyridine and pyridine-N-oxide molecules.

  4. Aromatic Amino Acids-Guanidinium Complexes through Cation-π Interactions

    Directory of Open Access Journals (Sweden)

    Cristina Trujillo

    2015-05-01

    Full Text Available Continuing with our interest in the guanidinium group and the different interactions than can establish, we have carried out a theoretical study of the complexes formed by this cation and the aromatic amino acids (phenylalanine, histidine, tryptophan and tyrosine using DFT methods and PCM-water solvation. Both hydrogen bonds and cation-π interactions have been found upon complexation. These interactions have been characterized by means of the analysis of the molecular electron density using the Atoms-in-Molecules approach as well as the orbital interactions using the Natural Bond Orbital methodology. Finally, the effect that the cation-π and hydrogen bond interactions exert on the aromaticity of the corresponding amino acids has been evaluated by calculating the theoretical NICS values, finding that the aromatic character was not heavily modified upon complexation.

  5. MODIFICATION OF TRANSITION METAL CATIONS TO POLYMER- STABILIZED PLATINUM COLLOIDAL CLUSTERS IN ENANTIOSELECTIVE HYDROGENATION OF METHYL PYRUVATE

    Institute of Scientific and Technical Information of China (English)

    Xiao-ping Yan; Bao-lin He; Jie Zhang; Han-fan Liu

    2005-01-01

    Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate. Compared to the enantiomeric excess (e.e.) value (71.4%)obtained without the presence of metal cations, obvious e.e. enhancement (up to 82.5%) was resulted from the addition of Zn2+ but with a certain decrease in activity. The reaction parameters in the presence of Zn2+ were also studied. It was found that the Pt colloidal catalysts in the presence of metal cations performed very differently from that in the absence of metal cations.

  6. Multicenter bond index analysis of influence of metal cations on the aromaticity of aromatic amino acids: Phenylalanine and tyrosine

    Science.gov (United States)

    Pakiari, A. H.; Farrokhnia, M.; Azami, S. M.

    2008-05-01

    In order to provide insight into the influence of metal cations on the aromaticity of amino acids, evaluation of six-center delocalization indices is accomplished in the context of quantum theory of atoms in molecules (QTAIM). Aromaticity of two amino acids, phenylalanine and tyrosine, is investigated as typical amino acids containing aromatic ring in their isolated state and complexed by some metal cations. The results showed that the metal cations affect the most important three connectivities differently. Also, it is shown that the existence of metal cations can increase two-center delocalization in certain parts of the aromatic rings.

  7. Preparation and Characterization of Cationic PLA-PEG Nanoparticles for Delivery of Plasmid DNA

    Directory of Open Access Journals (Sweden)

    Zou Weiwei

    2009-01-01

    Full Text Available Abstract The purpose of the present work was to formulate and evaluate cationic poly(lactic acid-poly(ethylene glycol (PLA-PEG nanoparticles as novel non-viral gene delivery nano-device. Cationic PLA-PEG nanoparticles were prepared by nanoprecipitation method. The gene loaded nanoparticles were obtained by incubating the report gene pEGFP with cationic PLA-PEG nanoparticles. The physicochemical properties (e.g., morphology, particle size, surface charge, DNA binding efficiency and biological properties (e.g., integrity of the released DNA, protection from nuclease degradation, plasma stability, in vitro cytotoxicity, and in vitro transfection ability in Hela cells of the gene loaded PLA-PEG nanoparticles were evaluated, respectively. The obtained cationic PLA-PEG nanoparticles and gene loaded nanoparticles were both spherical in shape with average particle size of 89.7 and 128.9 nm, polydispersity index of 0.185 and 0.161, zeta potentials of +28.9 and +16.8 mV, respectively. The obtained cationic PLA-PEG nanoparticles with high binding efficiency (>95% could protect the loaded DNA from the degradation by nuclease and plasma. The nanoparticles displayed sustained-release properties in vitro and the released DNA maintained its structural and functional integrity. It also showed lower cytotoxicity than Lipofectamine 2000 and could successfully transfect gene into Hela cells even in presence of serum. It could be concluded that the established gene loaded cationic PLA-PEG nanoparticles with excellent properties were promising non-viral nano-device, which had potential to make cancer gene therapy achievable.

  8. Influence of Divalent Cations on Deformation and Rupture of Adsorbed Lipid Vesicles.

    Science.gov (United States)

    Dacic, Marija; Jackman, Joshua A; Yorulmaz, Saziye; Zhdanov, Vladimir P; Kasemo, Bengt; Cho, Nam-Joon

    2016-06-28

    The fate of adsorbed lipid vesicles on solid supports depends on numerous experimental parameters and typically results in the formation of a supported lipid bilayer (SLB) or an adsorbed vesicle layer. One of the poorly understood questions relates to how divalent cations appear to promote SLB formation in some cases. The complexity arises from the multiple ways in which divalent cations affect vesicle-substrate and vesicle-vesicle interactions as well as vesicle properties. These interactions are reflected, e.g., in the degree of deformation of adsorbed vesicles (if they do not rupture). It is, however, experimentally challenging to measure the extent of vesicle deformation in real-time. Herein, we investigated the effect of divalent cations (Mg(2+), Ca(2+), Sr(2+)) on the adsorption of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipid vesicles onto silicon oxide- and titanium oxide-coated substrates. The vesicle adsorption process was tracked using the quartz crystal microbalance-dissipation (QCM-D) and localized surface plasmon resonance (LSPR) measurement techniques. On silicon oxide, vesicle adsorption led to SLB formation in all cases, while vesicles adsorbed but did not rupture on titanium oxide. It was identified that divalent cations promote increased deformation of adsorbed vesicles on both substrates and enhanced rupture on silicon oxide in the order Ca(2+) > Mg(2+) > Sr(2+). The influence of divalent cations on different factors in these systems is discussed, clarifying experimental observations on both substrates. Taken together, the findings in this work offer insight into how divalent cations modulate the interfacial science of supported membrane systems.

  9. Preparation and Characterization of Cationic PLA-PEG Nanoparticles for Delivery of Plasmid DNA

    Science.gov (United States)

    Zou, Weiwei; Liu, Chunxi; Chen, Zhijin; Zhang, Na

    2009-09-01

    The purpose of the present work was to formulate and evaluate cationic poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) nanoparticles as novel non-viral gene delivery nano-device. Cationic PLA-PEG nanoparticles were prepared by nanoprecipitation method. The gene loaded nanoparticles were obtained by incubating the report gene pEGFP with cationic PLA-PEG nanoparticles. The physicochemical properties (e.g., morphology, particle size, surface charge, DNA binding efficiency) and biological properties (e.g., integrity of the released DNA, protection from nuclease degradation, plasma stability, in vitro cytotoxicity, and in vitro transfection ability in Hela cells) of the gene loaded PLA-PEG nanoparticles were evaluated, respectively. The obtained cationic PLA-PEG nanoparticles and gene loaded nanoparticles were both spherical in shape with average particle size of 89.7 and 128.9 nm, polydispersity index of 0.185 and 0.161, zeta potentials of +28.9 and +16.8 mV, respectively. The obtained cationic PLA-PEG nanoparticles with high binding efficiency (>95%) could protect the loaded DNA from the degradation by nuclease and plasma. The nanoparticles displayed sustained-release properties in vitro and the released DNA maintained its structural and functional integrity. It also showed lower cytotoxicity than Lipofectamine 2000 and could successfully transfect gene into Hela cells even in presence of serum. It could be concluded that the established gene loaded cationic PLA-PEG nanoparticles with excellent properties were promising non-viral nano-device, which had potential to make cancer gene therapy achievable.

  10. Lipid Phases Eye View to Lipofection. Cationic Phosphatidylcholine Derivatives as Efficient DNA Carriers for Gene Delivery

    Directory of Open Access Journals (Sweden)

    Rumiana Koynova

    2008-01-01

    Full Text Available Efficient delivery of genetic material to cells is needed for tasks of utmost importance in laboratory and clinic, such as gene transfection and gene silencing. Synthetic cationic lipids can be used as delivery vehicles for nucleic acids and are now considered the most promising non-viral gene carriers. They form complexes (lipoplexes with the polyanionic nucleic acids. A critical obstacle for clinical application of the lipid-mediated DNA delivery (lipofection is its unsatisfactory efficiency for many cell types. Understanding the mechanism of lipid-mediated DNA delivery is essential for their successful application, as well as for rational design and synthesis of novel cationic lipoid compounds for enhanced gene delivery. According to the current understanding, the critical factor in lipid-mediated transfection is the structural evolution of lipoplexes within the cell, upon interacting and mixing with cellular lipids. In particular, recent studies with cationic phospha- tidylcholine derivatives showed that the phase evolution of lipoplex lipids upon interaction and mixing with membrane lipids appears to be decisive for transfection success: specifically, lamellar lipoplex formulations, which were readily susceptible to undergoing lamellar-nonlamellar (precisely lamellar-cubic phase transition upon mixing with cellular lipids, were found rather consistently associated with superior transfection potency, presumably as a result of facilitated DNA release subsequent to lipoplex fusion with the cellular membranes. Further, hydrophobic moiety of the cationic phospholipids was found able to strongly modulate liposomal gene delivery into primary human umbilical artery endothelial cells; superior activity was found for cationic phosphatidylcholine derivatives with two 14-carbon atom monounsaturated hydrocarbon chains, able to induce formation of cubic phase in membranes. Thus, understanding the lipoplex structure and the phase changes upon interacting

  11. From cation to oxide: hydroxylation and condensation of aqueous complexes; Du cation a l'oxyde: hydroxylation et condensation en solution

    Energy Technology Data Exchange (ETDEWEB)

    Jolivet, J.P. [Universite Pierre et Marie Curie, Chimie de la Matiere Condensee, URA CNRS 1466, 75 - Paris (France)

    1997-07-01

    Hydroxylation, condensation and precipitation of metal cations in aqueous solution are briefly reviewed. Hydroxylation of aqueous complexes essentially depends on the format charge (oxidation state), the size and the pH of the medium. It is the step allowing the condensation reaction. Depending on the nature of complexes (aqua-hydroxo, oxo-hydroxo), the. mechanism of condensation is different, olation or ox-olation respectively. The first one leads to poly-cations or hydroxides more or less stable against dehydration. The second one leads to poly-anions or oxides. Oligomeric species (poly-cations, poly-anions) are form from charged monomer complexes while the formation of solid phases requires non-charged precursors. Because of their high lability, charged oligomers are never the precursors of solids phases. The main routes for the formation of solid phases from solution are studied with two important and representative elements, Al and Si. For Al{sup 3+} ions, different methods (base addition in solution, thermo-hydrolysis, hydrothermal synthesis) are discussed in relation to the crystal structure of the solid phase obtained. For silicic species condensing by ox-olation, the role of acid or base catalysis on the morphology of gels is studied. The influence of complexing ligands on the processes and on the characteristics of solids (morphology of particles, basic salts and polymetallic oxides formation) is studied. (author)

  12. Microwaves spark emission spectroscopy for the analysis of cations: A simple form of atomic emission spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Zahid Hussain; Khalid Mohammed Khan; Khadim Hussain; Sadam Hussain; Shahnaz Perveen

    2011-01-01

    A novel method for the cation analysis was investigated. The analysis is based on the sparking of the salts of metals in a microwave oven after placing in a graphite cell. The graphite cell absorbs microwaves and produces high temperature which converts the salt into light emitting species. The colour of light was found to dependent on the nature of cation, however, the intensity of the emitted light was found to be depending upon the form and shape of the graphite assembly in addition to the concentration of the salt. This communication presents explanation for all these observations and for the systematic and quantitative analysis using microwave spark emission technique.

  13. Cationic zinc (II) dimers and one dimensional coordination polymer from ionic carboxylic acid

    Indian Academy of Sciences (India)

    Paladugu Suresh; Ganesan Prabusankar

    2014-09-01

    A rare example of chelating two tetra cationic paddle-wheel zinc dimers were synthesized from the reaction between flexible imidazolium carboxylate (LH2Br2) and corresponding zinc precursors. A zinc coordination polymer was synthesised by treating in situ generation of 2 in the presence of 4,4′-bipyridine. These new molecules, dimers and polymer, were characterized by FT-IR, NMR, UV-vis, fluorescent and single crystal X-ray diffraction techniques. Zinc polymer is the first example of 1D coordination polymer constructed by tetra cationic zinc dimer as a secondary building unit in coordination polymer.

  14. Defining the Catechol-Cation Synergy for Enhanced Wet Adhesion to Mineral Surfaces.

    Science.gov (United States)

    Rapp, Michael V; Maier, Greg P; Dobbs, Howard A; Higdon, Nicholas J; Waite, J Herbert; Butler, Alison; Israelachvili, Jacob N

    2016-07-27

    Mussel foot proteins (Mfps) exhibit remarkably adaptive adhesion and bridging between polar surfaces in aqueous solution despite the strong hydration barriers at the solid-liquid interface. Recently, catechols and amines-two functionalities that account for >50 mol % of the amino acid side chains in surface-priming Mfps-were shown to cooperatively displace the interfacial hydration and mediate robust adhesion between mineral surfaces. Here we demonstrate that (1) synergy between catecholic and guanidinium side chains similarly promotes adhesion, (2) increasing the ratio of cationic amines to catechols in a molecule reduces adhesion, and (3) the catechol-cation synergy is greatest when both functionalities are present within the same molecule.

  15. Effect of the counter cation on the third order nonlinearity in anionic Au dithiolene complexes

    Science.gov (United States)

    Iliopoulos, K.; El-Ghayoury, A.; Derkowska, B.; Ranganathan, A.; Batail, P.; Gindre, D.; Sahraoui, B.

    2012-12-01

    In this work, we present the third order nonlinear optical investigation of two gold complexes, which differ by the nature of the counter cations. The impact of the different design in the architecture through a set of hydrogen bonds in the case of Au-Mel of the systems on the nonlinearity has been studied by means of the Z-scan setup under 532 nm, 30 ps laser excitation, allowing for the determination of the nonlinear absorption and refraction of the samples. Significant modification of the nonlinear optical response between the two metal complexes has been found suggesting a clear effect of the counter cation.

  16. Fingerprinting DNA oxidation processes: IR characterization of the 5-methyl-2'-deoxycytidine radical cation.

    Science.gov (United States)

    Bucher, Dominik B; Pilles, Bert M; Pfaffeneder, Toni; Carell, Thomas; Zinth, Wolfgang

    2014-02-24

    Methylated cytidine plays an important role as an epigenetic signal in gene regulation. Its oxidation products are assumed to be involved in active demethylation processes but also in damaging DNA. Here, we report the photochemical production of the 5-methyl-2'-deoxycytidine radical cation via a two-photon ionization process. The radical cation is detected by time-resolved IR spectroscopy and identified by band assignment using density functional theory calculations. Two final oxidation products are characterized with liquid chromatography coupled to mass spectrometry.

  17. Paddle-wheel versus percolation mechanism for cation transport in some sulphate phases

    DEFF Research Database (Denmark)

    Andersen, N.H.; Bandaranyake, P.W.S.K.; Careem, M.A.;

    1992-01-01

    Lithium sulphate and a few other compounds have high temperature phases which are both solid electrolytes and plastic crystals (rotor phases). Three types of experiments are here considered in order to test the validity of a "paddle-wheel mechanism" that has been proposed for cation conductivity...... and interdiffusion, all studied mono- and divalent cations are very mobile in the rotor phases, which lack the pronounced correlation with ionic radii that is characteristic for diffusion in other classes of solid electrolytes. The quoted studies are to be considered as strong evidence against a percolation model...

  18. DFT studies of all fluorothiophenes and their cations as candidate monomers for conductive polymers

    Energy Technology Data Exchange (ETDEWEB)

    Shirani, Hossein, E-mail: shiranihossein@gmail.com [Young Researchers Club, Islamic Azad University, Toyserkan Branch, Toyserkan (Iran, Islamic Republic of); Jameh-Bozorghi, Saeed [Department of Chemistry, Islamic Azad University, Arak Branch, Arak (Iran, Islamic Republic of); Yousefi, Ali [Department of Computer Engineering, Islamic Azad University, Hamedan Branch, Hamedan (Iran, Islamic Republic of)

    2015-01-22

    In this paper, electronic, structural, and properties of mono-, di-, tri-, and tetrafluorothiophenes and their radical cations are studied using the density functional theory and B3LYP method with 6-311++G** basis set. Also, the effects of the number and position of the substituent of fluorine atoms on the properties of the thiophene ring have been studied using optimized structures obtained for these molecules and their radical cations; vibrational frequencies, spin-density distribution, size and direction of the dipole moment vector, ionization potential, electric Polarizabilities, HOMO–LUMO gaps and NICS values of these compounds have been calculated and analyzed.

  19. RESEARCH ON THE VARIATION OF SOME BIVALENT CATIONS IN PATIENTS WITH DISEASES OF THE ORAL CAVITY

    Directory of Open Access Journals (Sweden)

    Daniel PAVAL

    2016-03-01

    Full Text Available The concentration of bivalent cations affects a large number of processes that occur in the oro-maxillary region. A connection has been established between chronic periodontitis, on one side, and the salivary concentration of calcium, magnesium, zinc and copper and the concentration of magnesium in blood, on the other. Patients with suppurations on oro-maxillo-facial area show decreased blood calcium concentration and increased salivary magnesium concentration. In the synthesis of dental enamel, calcium, magnesium, zinc and copper play important roles. Changes in the salivary concentration of bivalent cations are directly involved in some maxillary diseases and in tooth decay.

  20. Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

    Directory of Open Access Journals (Sweden)

    V. Romero

    2012-01-01

    A study of time evolution of the impedance curves measured in the system “IL aqueous solution/Nafion-112 membrane/IL aqueous solution” was also performed. This study allows us monitoring the electrical changes associated to the IL-cation incorporation in both the membrane and the membrane/IL solution interface, and it provides supplementary information on the characteristic of the Nafion/DTA+ hybrid material. Moreover, the results also show the significant effect of water on the electrical resistance of the Nafion-112/IL-cation-modified membrane.

  1. DNA induced sequestration of a bioactive cationic fluorophore from the lipid environment: A spectroscopic investigation.

    Science.gov (United States)

    Ghosh, Saptarshi; Kundu, Pronab; Chattopadhyay, Nitin

    2016-01-01

    The effect of calf-thymus DNA (ctDNA) on the lipid bound probe, formed by the cationic phenazinium dye phenosafranin (PSF) and the anionic lipid dimyristoyl-L-α-phosphatidylglycerol (DMPG), has been unearthed exploiting various spectroscopic techniques. Steady state and time-resolved fluorometric studies and measurements of circular dichroism and DNA helix melting temperature reveal that in the presence of DNA the probe is dislodged from the lipid environment and gets intercalated within the DNA helix. The work qualitatively illustrates that the anionic lipid can be used as a potential nanocarrier for delivering the cationic drugs to the most relevant biomacromolecular target, DNA.

  2. Periodic model of LTA framework containing various non-tetrahedral cations.

    Science.gov (United States)

    Koleżyński, A; Mikuła, A; Król, M

    2016-03-15

    A simplified periodic model of Linde Type A zeolite (LTA) structure with various selected mono- and di-valent extra-framework cations was formulated. Ab initio calculations (geometry optimization and vibrational spectra calculations) using the proposed model were carried out by means of Crystal09 program. The resulting structures and simulated spectra were analyzed in detail and compared with the experimental ones. The presented results show that in most cases the proposed model agrees well with experimental results. Individual bands were assigned to respective normal modes of vibration and the changes resulting from the selective substitution of extra framework cations were described and explained.

  3. Modulation of fast synaptic transmission by presynaptic ligand-gated cation channels.

    Science.gov (United States)

    Khakh, B S; Henderson, G

    2000-07-01

    There is now considerable evidence demonstrating that ligand-gated cation channels (i.e., P2X, nicotinic, kainate, NMDA, AMPA and 5-HT(3) receptors), in addition to mediating fast excitatory neurotransmission, may be located presynaptically on nerve terminals in the peripheral and central nervous systems where they function to modulate neurotransmitter release. This modulation can be facilitation, inhibition or both. In this article, we first outline the multiple mechanisms by which activation of presynaptic ligand-gated cation channels can modulate spontaneous and evoked neurotransmitter release, before reviewing in detail published electrophysiological studies of presynaptic P2X, nicotinic, kainate, NMDA, AMPA and 5-HT(3) receptors.

  4. Adsorption Capability of Cationic Dyes (Methylene Blue and Crystal Violet) onto Poly-γ-glutamic Acid.

    Science.gov (United States)

    Ogata, Fumihiko; Nagai, Noriaki; Kawasaki, Naohito

    2017-01-01

    In this study, the adsorption capability of cationic dyes, which were methylene blue and crystal violet, by poly-γ-glutamic acid (PGA) in a single or binary solution system was investigated. The effect of the molecular weight of PGA, initial dye concentration, solution pH, and temperature on the adsorption of dyes was evaluated. The adsorption mechanism of dyes onto PGA was the interaction between -COOH group on the PGA surface and the polarity groups of dyes. These results indicated that PGA is useful for removal of dyes and cationic organic compounds from a single or binary solution system.

  5. Radiation induced redox reactions and fragmentation of constituent ions in ionic liquids. 2. Imidazolium cations.

    Science.gov (United States)

    Shkrob, Ilya A; Marin, Timothy W; Chemerisov, Sergey D; Hatcher, Jasmine L; Wishart, James F

    2011-04-14

    In part 1 of this study, radiolytic degradation of constituent anions in ionic liquids (ILs) was examined. The present study continues the themes addressed in part 1 and examines the radiation chemistry of 1,3-dialkyl substituted imidazolium cations, which currently comprise the most practically important and versatile class of ionic liquid cations. For comparison, we also examined 1,3-dimethoxy- and 2-methyl-substituted imidazolium and 1-butyl-4-methylpyridinium cations. In addition to identification of radicals using electron paramagnetic resonance spectroscopy (EPR) and selective deuterium substitution, we analyzed stable radiolytic products using (1)H and (13)C nuclear magnetic resonance (NMR) and tandem electrospray ionization mass spectrometry (ESMS). Our EPR studies reveal rich chemistry initiated through "ionization of the ions": oxidation and the formation of radical dications in the aliphatic arms of the parent cations (leading to deprotonation and the formation of alkyl radicals in these arms) and reduction of the parent cation, yielding 2-imidazolyl radicals. The subsequent reactions of these radicals depend on the nature of the IL. If the cation is 2-substituted, the resulting 2-imidazolyl radical is relatively stable. If there is no substitution at C(2), the radical then either is protonated or reacts with the parent cation forming a C(2)-C(2) σσ*-bound dimer radical cation. In addition to these reactions, when methoxy or C(α)-substituted alkyl groups occupy the N(1,3) positions, their elimination is observed. The elimination of methyl groups from N(1,3) was not observed. Product analyses of imidazolium liquids irradiated in the very-high-dose regime (6.7 MGy) reveal several detrimental processes, including volatilization, acidification, and oligomerization. The latter yields a polymer with m/z of 650 ± 300 whose radiolytic yield increases with dose (~0.23 monomer units per 100 eV for 1-methyl-3-butylimidazolium trifluorosulfonate). Gradual

  6. Electronic structure of the radical-cations of phenothiazine and its structural analogs

    Energy Technology Data Exchange (ETDEWEB)

    Turchaninov, V.K.; Ermikov, A.F.; Shagun, V.A.

    1986-09-20

    The electronic structure of the radical-cations of phenothiazine and some of its derivatives and heteroanalogs was investigated by electronic absorption spectroscopy. On the basis of the obtained results and also of the data from photoelectron spectroscopy of the parent molecules, quantum-chemical calculations (MINDO/3), and published data it was concluded that the occupied molecular orbitals of the excess-..pi.. heteroatomic system exhibit different sensitivities to hole formation. It is suggested that this is due to the different degrees of delocalization of the unpaired electron in the ground and electronically excited states of the radical cation of such molecules.

  7. Chemical-garden formation, morphology, and composition. I. Effect of the nature of the cations.

    Science.gov (United States)

    Cartwright, Julyan H E; Escribano, Bruno; Sainz-Daz, C Ignacio

    2011-04-05

    We have grown chemical gardens in different sodium silicate solutions from several metal-ion salts--calcium chloride, manganese chloride, cobalt chloride, and nickel sulfate--with cations from period 4 of the periodic table. We have studied their formation process using photography, examined the morphologies produced using scanning electron microscopy (SEM), and analyzed chemical compositions using X-ray powder diffraction (XRD) and energy dispersive X-ray analysis (EDX) to understand better the physical and chemical processes involved in the chemical-garden reaction. We have identified different growth regimes in these salts that are dependent on the concentration of silicate solution and the nature of the cations involved.

  8. Spectral and Acid-Base Properties of Hydroxyflavones in Micellar Solutions of Cationic Surfactants

    Science.gov (United States)

    Lipkovska, N. A.; Barvinchenko, V. N.; Fedyanina, T. V.; Rugal', A. A.

    2014-09-01

    It has been shown that the spectral characteristics (intensity, position of the absorption band) and the acid-base properties in a series of structurally similar hydroxyflavones depend on the concentration of the cationic surfactants miramistin and decamethoxin in aqueous solutions, and the extent of their changes is more pronounced for hydrophobic quercetin than for hydrophilic rutin. For the first time, we have determined the apparent dissociation constants of quercetin and rutin in solutions of these cationic surfactants (pKa1) over a broad concentration range and we have established that they decrease in the series water-decamethoxin-miramistin.

  9. Periodic model of LTA framework containing various non-tetrahedral cations

    Science.gov (United States)

    Koleżyński, A.; Mikuła, A.; Król, M.

    2016-03-01

    A simplified periodic model of Linde Type A zeolite (LTA) structure with various selected mono- and di-valent extra-framework cations was formulated. Ab initio calculations (geometry optimization and vibrational spectra calculations) using the proposed model were carried out by means of Crystal09 program. The resulting structures and simulated spectra were analyzed in detail and compared with the experimental ones. The presented results show that in most cases the proposed model agrees well with experimental results. Individual bands were assigned to respective normal modes of vibration and the changes resulting from the selective substitution of extra framework cations were described and explained.

  10. A Bioluminescence Assay System for Imaging Metal Cationic Activities in Urban Aerosols.

    Science.gov (United States)

    Kim, Sung-Bae; Naganawa, Ryuichi; Murata, Shingo; Nakayama, Takayoshi; Miller, Simon; Senda, Toshiya

    2016-01-01

    A bioluminescence-based assay system was fabricated for an efficient determination of the activities of air pollutants. The following four components were integrated into this assay system: (1) an 8-channel assay platform uniquely designed for simultaneously sensing multiple optical samples, (2) single-chain probes illuminating toxic chemicals or heavy metal cations from air pollutants, (3) a microfluidic system for circulating medium mimicking the human body, and (4) the software manimulating the above system. In the protocol, we briefly introduce how to integrate the components into the system and the application to the illumination of the metal cationic activities in air pollutants.

  11. Design, synthesis and antimicrobial properties of non-hemolytic cationic alpha-cyclopeptoids.

    Science.gov (United States)

    Comegna, Daniela; Benincasa, Monica; Gennaro, Renato; Izzo, Irene; De Riccardis, Francesco

    2010-03-01

    The synthesis and screening of neutral and cationic, linear and cyclic peptoids (N-alkylglycine peptidomimetics) is described. Structure-activity relationship studies show that the in vitro activities of the tested peptoids depend on both cyclization and decoration with cationic groups. The most powerful N-lysine cyclopeptoid derivatives showed good antifungal activity against Candida albicans (ATCC90029 and L21) and Candida famata (SA550, Amph B-resistant) and low hemolytic activity. The effects of the cyclic peptoids on membrane permeabilization were evaluated by the propidium iodide exclusion assay.

  12. Cation and anion dependence of stable geometries and stabilization energies of alkali metal cation complexes with FSA(-), FTA(-), and TFSA(-) anions: relationship with physicochemical properties of molten salts.

    Science.gov (United States)

    Tsuzuki, Seiji; Kubota, Keigo; Matsumoto, Hajime

    2013-12-19

    Stable geometries and stabilization energies (Eform) of the alkali metal complexes with bis(fluorosulfonyl)amide, (fluorosulfonyl)(trifluoromethylslufonyl)amide and bis(trifluoromethylsulfonyl)amide (FSA(-), FTA(-) and TFSA(-)) were studied by ab initio molecular orbital calculations. The FSA(-) complexes prefer the bidentate structures in which two oxygen atoms of two SO2 groups have contact with the metal cation. The FTA(-) and TFSA(-) complexes with Li(+) and Na(+) prefer the bidentate structures, while the FTA(-) and TFSA(-) complexes with Cs(+) prefer tridentate structures in which the metal cation has contact with two oxygen atoms of an SO2 group and one oxygen atom of another SO2 group. The two structures are nearly isoenergetic in the FTA(-) and TFSA(-) complexes with K(+) and Rb(+). The magnitude of Eform depends on the alkali metal cation significantly. The Eform calculated for the most stable TFSA(-) complexes with Li(+), Na(+), K(+), Rb(+) and Cs(+) cations at the MP2/6-311G** level are -137.2, -110.5, -101.1, -89.6, and -84.1 kcal/mol, respectively. The viscosity and ionic conductivity of the alkali TFSA molten salts have strong correlation with the magnitude of the attraction. The viscosity increases and the ionic conductivity decreases with the increase of the attraction. The melting points of the alkali TFSA and alkali BETA molten salts also have correlation with the magnitude of the Eform, which strongly suggests that the magnitude of the attraction play important roles in determining the melting points of these molten salts. The anion dependence of the Eform calculated for the complexes is small (less than 2.9 kcal/mol). This shows that the magnitude of the attraction is not the cause of the low melting points of alkali FTA molten salts compared with those of corresponding alkali TFSA molten salts. The electrostatic interactions are the major source of the attraction in the complexes. The electrostatic energies for the most stable TFSA

  13. Effect of the Starch Source on the Performance of Cationic Starches having Similar Degree of Substitution for Papermaking using Deinked Pulp

    Directory of Open Access Journals (Sweden)

    Jin Liu

    2014-12-01

    Full Text Available Cationic waxy corn starch was prepared from waxy corn starch with 2,3-epoxypropyl trimethyl ammonium chloride (ETMAC as a cationic etherifying reagent. Its structure was identified by Fourier transform infrared (FTIR spectroscopy, scanning electron microscopy (SEM, and X-ray powder diffraction (XRD. The results showed that quaternary ammonium groups were introduced successfully into the waxy corn starch, and the cationic reaction occurred on the surface of the starch granules. Cationic waxy corn starch was then applied into deinked pulp as a paper reinforcer, and the result was compared with that of cationic tapioca starch and cationic maize starch. In general, the physical strengths of the paper were improved significantly with an increasing dosage of cationic starches. Cationic waxy corn starch was superior in terms of enhancing the physical properties of paper. In addition, with the use of cationic waxy corn starch, anionic trash in the slurry could be better removed.

  14. Driving force for the hydration of the swelling clays: case of montmorillonites saturated with alkaline-earth cations.

    Science.gov (United States)

    Salles, Fabrice; Douillard, Jean-Marc; Bildstein, Olivier; Gaudin, Cedric; Prelot, Benedicte; Zajac, Jerzy; Van Damme, Henri

    2013-04-01

    Important structural modifications occur in swelling clays upon water adsorption. The multi-scale evolution of the swelling clay structure is usually evidenced by various experimental techniques. However, the driving force behind such phenomena is still not thoroughly understood. It appears strongly dependent on the nature of the interlayer cation. In the case of montmorillonites saturated with alkaline cations, it was inferred that the compensating cation or the layer surface could control the hydration process and thus the opening of the interlayer space, depending on the nature of the interlayer cation. In the present study, emphasis is put on the impact of divalent alkaline-earth cations compensating the layer charge in montmorillonites. Since no experimental technique offers the possibility of directly determining the hydration contributions related to interlayer cations and layer surfaces, an approach based on the combination of electrostatic calculations and immersion data is developed here, as already validated in the case of montmorillonites saturated by alkaline cations. This methodology allows to estimate the hydration energy for divalent interlayer cations and therefore to shed a new light on the driving force for hydration process occurring in montmorillonites saturated with alkaline-earth cations. Firstly, the surface energy values obtained from the electrostatic calculations based on the Electronegativity Equalization Method vary from 450 mJ m(-2) for Mg-montmorillonite to 1100 mJ m(-2) for Ba-montmorillonite. Secondly, considering both the hydration energy for cations and layer surfaces, the driving force for the hydration of alkaline-earth saturated montmorillonites can be attributed to the interlayer cation in the case of Mg-, Ca-, Sr-montmorillonites and to the interlayer surface in the case of Ba-montmorillonites. These results explain the differences in behaviour upon water adsorption as a function of the nature of the interlayer cation

  15. Do the cations in clay and the polymer matrix affect quantum dot fluorescent properties?

    Science.gov (United States)

    Wei, Wenjun; Liu, Cui; Liu, Jiyan; Liu, Xueqing; Zou, Linling; Cai, Shaojun; Shi, Hong; Cao, Yuan-Cheng

    2016-06-01

    This paper studied the effects of cations and polymer matrix on the fluorescent properties of quantum dots (QDs). The results indicated that temperature has a greater impact on fluorescence intensity than clay cations (mainly K(+) and Na(+) ). Combined fluorescence lifetime and steady-state spectrometer tests showed that QD lifetimes all decreased when the cation concentration was increased, but the quantum yields were steady at various cation concentrations of 0, 0.05, 0.5 and 1 M. Poly(ethylene oxide) (PEO), poly(vinyl alcohol) (PVA) and diepoxy resin were used to study the effects of polymers on QD lifetime and quantum yield. The results showed that the lifetime for QDs 550 nm in PEO and PVA was 17.33 and 17.12 ns, respectively; for the epoxy resin, the lifetime was 0.74 ns, a sharp decrease from 24.47 ns. The quantum yield for QDs 550 nm changed from 34.22% to 7.45% and 7.81% in PEO and PVA, respectively; for the epoxy resin the quantum yield was 2.25%. QDs 580 nm and 620 nm showed the same results as QDs 550 nm. This study provides useful information on the design, synthesis and application of QDs-polymer luminescent materials. Copyright © 2015 John Wiley & Sons, Ltd.

  16. Reasons Behind the Growing Popularity of Sino-Foreign Cooperative Edu-cational Programs

    Institute of Scientific and Technical Information of China (English)

    YANG Wei

    2016-01-01

    The continuously expanding program scale and increasing student enrollment number of Sino-foreign cooperative edu-cational programs in recent years have demonstrated their increasing acceptance among Chinese students. This paper aims to ex-plore and analyze the reasons behind the growing popularity of Sino-foreign joint educational programs.

  17. Correlation among electronegativity, cation polarizability, optical basicity and single bond strength of simple oxides

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrov, Vesselin, E-mail: vesselin@uctm.edu [Department of Silicate Technology, University of Chemical Technology and Metallurgy, 8, Kl. Ohridski Blvd., Sofia 1756 (Bulgaria); Komatsu, Takayuki, E-mail: komatsu@mst.nagaokaut.ac.jp [Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan)

    2012-12-15

    A suitable relationship between free-cation polarizability and electronegativity of elements in different valence states and with the most common coordination numbers has been searched on the basis of the similarity in physical nature of both quantities. In general, the cation polarizability increases with decreasing element electronegativity. A systematic periodic change in the polarizability against the electronegativity has been observed in the isoelectronic series. It has been found that generally the optical basicity increases and the single bond strength of simple oxides decreases with decreasing the electronegativity. The observed trends have been discussed on the basis of electron donation ability of the oxide ions and type of chemical bonding in simple oxides. - Graphical abstract: This figure shows the single bond strength of simple oxides as a function of element electronegativity. A remarkable correlation exists between these independently obtained quantities. High values of electronegativity correspond to high values of single bond strength and vice versa. It is obvious that the observed trend in this figure is closely related to the type of chemical bonding in corresponding oxide. Highlights: Black-Right-Pointing-Pointer A suitable relationship between free-cation polarizability and electronegativity of elements was searched. Black-Right-Pointing-Pointer The cation polarizability increases with decreasing element electronegativity. Black-Right-Pointing-Pointer The single bond strength of simple oxides decreases with decreasing the electronegativity. Black-Right-Pointing-Pointer The observed trends were discussed on the basis of type of chemical bonding in simple oxides.

  18. Cationic liposomal drug delivery system for specific targeting of human cd14+ monocytes in whole blood

    DEFF Research Database (Denmark)

    2013-01-01

    This invention concerns a liposome comprising lipids and at least one active ingredient, wherein at least one of the lipids is a cationic lipid; said liposome exhibiting a net positive charge at physiological conditions at which said liposome preferentially adheres to monocytes in freshly drawn b......, an infectious disease, an inflammatory disease, an autoimmune disease or allergy....

  19. Interaction of polyamines with proteins of photosystem II: Cation binding and photosynthetic oxygen evolution

    Science.gov (United States)

    Beauchemin, R.; Harnois, J.; Rouillon, R.; Tajmir-Riahi, H. A.; Carpentier, R.

    2007-05-01

    Polyamines are organic cations that function in diverse physiological processes that share as a common thread a close relationship to cell proliferation and growth. Polyamines also affect photosynthetic oxygen evolution and therefore, this study was designed to investigate the interaction of 1,3-diaminopropane, 1,4-diaminobutane (putrescine), and 1,5-diaminopentane (cadaverine) cations with proteins of photosystem II (PSII) using PSII-enriched submembrane fractions with diamine concentrations between 0.01 and 20 mM. Fourier transformed infrared (FTIR) difference spectroscopy with its self-deconvolution and second derivative resolution enhancement, as well as curve-fitting procedures were applied in order to determine the diamine binding mode, the protein conformational changes, and the structural properties of diamine-protein complexes. Spectroscopic evidence showed that diamines interact with proteins (H-bonding) through polypeptide C dbnd O groups with no major perturbations of protein secondary structure. At very low diamine concentration (0.01 mM), no inhibition of oxygen-evolution occurred, while at higher diamine content (5-10 mM), 100% inhibition was observed. Chorophyll fluorescence measurements demonstrated that the inhibition mainly affects the oxygen evolving complex of PSII. Comparisons of the effects of these dipositive organic cations with divalent metal cations on one hand and with polyvalent spermine and spermidine on the other hand, show major alterations of the protein secondary structure as positive charge increases.

  20. Cationic Effect on the Electrochemical Characteristics of the Hydrothermally Grown Manganese Dioxide

    Science.gov (United States)

    Vernardou, D.; Kazas, A.; Apostolopoulou, M.; Katsarakis, N.; Koudoumas, E.

    2017-04-01

    Hydrothermal growth of manganese dioxide (MnO2) nanostructures was carried out on indium tin dioxide glass substrates at 95°C for 24 h to study the effect of cations such as K+, Li+, and Na+ on their properties. It was observed that presence of cations affected the MnO2 phase and morphology: amorphous MnO2 (no cations) showed columnar-like structure, ɛ-MnO2 (K+) presented nanowires, α-MnO2 (Na+) was composed of agglomerates of spherical nanoparticles, while β-MnO2 (Li+) consisted of spherical aggregates of nanoparticles. The different electrochemical performance depending on the structure is expected to be useful for application in Li-ion batteries. As-grown ɛ-MnO2 exhibited lower charge resistance and higher ionic diffusion rate, providing the electrode with enhanced specific discharge capacity of 910 mAh g-1 and capacity retention of 98% after 500 scans. Hence, K+ can support tunnel structures and stabilize the structure compared with the smaller cations Na+ and Li+.