Synthesis and properties of novel sulfonated polyimides from 2,2?-bis(4-aminophenoxy)biphenyl-5,5?-disulfonic acid

2004 ◽  
Vol 42 (6) ◽  
pp. 1432-1440 ◽  
Author(s):  
Xiaoxia Guo ◽  
Jianhua Fang ◽  
Kazuhiro Tanaka ◽  
Hidetoshi Kita ◽  
Ken-ichi Okamoto
Keyword(s):  
Disulfonic Acid ◽  
Sulfonated Polyimides

Novel Sulfonated Polyimides as Polyelectrolytes for Fuel Cell Application. 2. Synthesis and Proton Conductivity of Polyimides from 9,9-Bis(4-aminophenyl)fluorene-2,7-disulfonic Acid

2002 ◽  
Vol 35 (17) ◽  
pp. 6707-6713 ◽  
Author(s):  
Xiaoxia Guo ◽  
Jianhua Fang ◽  
Tatsuya Watari ◽  
Kazuhiro Tanaka ◽  
Hidetoshi Kita ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Proton Conductivity ◽  
Disulfonic Acid ◽  
Fuel Cell Application ◽  
Sulfonated Polyimides

A Study of Linear versus Kinked Bulky Polymers for Proton Exchange Membranes Using Sulfonated Polyimides

2014 ◽  
Vol 670-671 ◽  
pp. 133-136
Author(s):  
Yu Han Li
Keyword(s):  
Proton Conductivity ◽  
Water Uptake ◽  
Sulfonic Acid ◽  
Main Chain ◽  
Acid Group ◽  
Proton Exchange ◽  
Membrane Properties ◽  
Disulfonic Acid ◽  
Linear Polymers ◽  
Sulfonated Polyimides

Linear and kinked bulky monomers were incorporated into the main chain of a polyimide in order to investigate the effect of kinked versus linear polymers on membrane properties such as water uptake and proton conductivity. Polymers prepared using linear 1,4-bis (4-aminophenoxy)-naphthyl-2,7-disulfonic acid (BAPNDS), SPI-N, and using kinked 2,2’-bis (p-aminophenoxy)-1,1’-binaphthyl-6,6’-disulfonic acid (BNDADS), SPI-BN, were cast into membranes. All the copolymers showed excellent solubility and good film-forming capability. Membranes are thermally stable up to 300 °C under air. For SPI-BN, the nonplanar binaphthyl group result in polymer chain relaxation and produce large water uptake. However, the conductivity of kinked, SPI-BN membranes is lower than those prepared from SPI-N for a given IEC but water uptakes are higher. This might be related to substitution position of the sulfonic acid groups and the microstructure. Sulfonic acid group were located at the same side of the main chain will be favorable for forming hydrophilic clusters, thus better proton conductivity performance would be achieved.

Synthesis and characterization of novel sulfonated polyimides from 1,4-bis(4-aminophenoxy)-naphthyl-2,7-disulfonic acid

Polymer ◽  
2007 ◽  
Vol 48 (8) ◽  
pp. 2280-2287 ◽  
Author(s):  
Yuhan Li ◽  
Rizhe Jin ◽  
Zhiming Cui ◽  
Zhen Wang ◽  
Wei Xing ◽  
...  
Keyword(s):  
Disulfonic Acid ◽  
Synthesis And Characterization ◽  
Sulfonated Polyimides

scholarly journals The signaling role of extracellular ATP in co-culture of Shiraia sp. S9 and Pseudomonas fulva SB1 for enhancing hypocrellin A production

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Xin Ping Li ◽  
Lu Lu Zhou ◽  
Yan Hua Guo ◽  
Jian Wen Wang
Keyword(s):  
Atp Release ◽  
Specific Inhibitor ◽  
Extracellular Atp ◽  
Oxidase Inhibitor ◽  
Disulfonic Acid ◽  
Early Event ◽  
Fungal Metabolites ◽  
Extracellular Signaling ◽  
Hypocrellin A

Abstract Background Adenosine 5′-triphosphate (ATP) plays both a central role as an intracellular energy source, and a crucial extracellular signaling role in diverse physiological processes of animals and plants. However, there are less reports concerning the signaling role of microbial extracellular ATP (eATP). Hypocrellins are effective anticancer photodynamic therapy (PDT) agents from bambusicolous Shiraia fungi. The co-culture of Shiraia sp. S9 and a bacterium Pseudomonas fulva SB1 isolated from Shiraia fruiting bodies was established for enhanced hypocrellin A (HA) production. The signaling roles of eATP to mediate hypocrellin biosynthesis were investigated in the co-culture. Results The co-culture induced release of eATP at 378 nM to the medium around 4 h. The eATP release was interdependent on cytosolic Ca2+ concentration and reactive oxygen species (ROS) production, respectively. The eATP production could be suppressed by the Ca2+ chelator EGTA or abolished by the channel blocker La3+, ROS scavenger vitamin C and NADPH oxidase inhibitor diphenyleneiodonium chloride (DPI). The bacterium-induced H2O2 production was strongly inhibited by reactive blue (RB), a specific inhibitor of membrane purinoceptors, but dependent on the induced Ca2+ influx in the co-culture. On the other hand, the application of exogenous ATP (exATP) at 10–300 µM to Shiraia cultures also promoted fungal conidiation and HA production, both of which were blocked effectively by the purinoceptor inhibitors pyridoxalphosphate-6-azophenyl-2′, 4′-disulfonic acid (PPADS) and RB, and ATP hydrolase apyrase. Both the induced expression of HA biosynthetic genes and HA accumulation were inhibited significantly under the blocking of the eATP or Ca2+ signaling, and the scavenge of ROS in the co-culture. Conclusions Our results indicate that eATP release is an early event during the intimate bacterial–fungal interaction and eATP plays a signaling role in the bacterial elicitation on fungal metabolites. Ca2+ and ROS are closely linked for activation of the induced ATP release and its signal transduction. This is the first report on eATP production in the fungal–bacterial co-culture and its involvement in the induced biosynthesis of fungal metabolites. Graphic abstract

Chemical modification of Ca(2+)-activated potassium channels of GH3 anterior pituitary cells

1992 ◽  
Vol 263 (5) ◽  
pp. C1081-C1087 ◽  
Author(s):  
A. M. Frace ◽  
D. C. Eaton
Keyword(s):  
Single Channel ◽  
Gh3 Cells ◽  
Disulfonic Acid ◽  
State Transitions ◽  
Trinitrobenzene Sulfonic Acid ◽  
Voltage Sensitivity ◽  
Pituitary Cells ◽  
Amino Groups ◽  
Open Probability ◽  
Long Duration

The effects of amino group specific reagents were examined on single, large-conductance, Ca(2+)-activated, K+ channels in excised membrane patches from GH3 cells. The reagents used include trinitrobenzene sulfonic acid, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and its 4-acetamido derivative, and sulfophenyl-isothiocyanate. These reagents react covalently with peptide terminal amino groups and the epsilon amino groups of lysine residues, thereby removing positive charge. Internal application of 0.1-1.0 mM reagent to inside-out patches irreversibly increases channel open probability. Single-channel conductance and voltage sensitivity are not affected by modification. Analysis of channel openings and closures shows that the increase in open probability is predominantly due to the loss of long-duration closures of the channel; however, the lengths of long-duration openings are increased. After the modification in the presence of Ca2+ was performed, the channel open probability remains large, regardless of the internal Ca2+ concentration. Transitions among several open and closed states of the modified channel are present in the absence of Ca2+, suggesting that many state transitions are not directly dependent on Ca2+ binding or dissociation.

Luminal flow rate regulates proximal tubule H-HCO3 transporters

1992 ◽  
Vol 262 (1) ◽  
pp. F47-F54 ◽  
Author(s):  
P. A. Preisig
Keyword(s):  
Proximal Tubule ◽  
Flow Rate ◽  
Initial Rate ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Rate Dependence ◽  
Unstirred Layer ◽  
Disulfonic Acid ◽  
Luminal Flow

In vivo microperfusion was used to examine the mechanism of luminal flow rate dependence of proximal tubule acidification. Luminal flow rate was acutely changed between 5 and 40 nl/min, while luminal and peritubular capillary composition were held constant. With inhibition of basolateral membrane base transport by peritubular 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), cell pH (pHi) provides a sensitive index of apical membrane H secretory activity. At a luminal perfusate [HCO3] of 25 mM, progressive increases in luminal flow rate (5----15----25----40 nl/min) caused progressive increases in pHi. This effect was of a smaller magnitude with a luminal perfusate [HCO3] of 60 mM and was further decreased at a luminal perfusate [HCO3] of 100 mM. This pattern of diminished flow rate dependence at higher luminal [HCO3] is consistent with the presence of a luminal unstirred layer, whose composition can be modified by luminal flow rate. The activity of the apical membrane Na-H antiporter, assayed as the initial rate of pHi recovery from an acid load in the presence of peritubular DIDS, was faster at 40 compared with 5 nl/min. Basolateral membrane Na-3HCO3 symporter activity, assayed as the initial rate of pHi recovery from an alkali load in the absence of luminal and peritubular chloride, was faster at 40 compared with 5 nl/min. This effect was eliminated by luminal amiloride, suggesting an indirect effect of flow mediated by changes in pHi secondary to flow rate-dependent changes in apical membrane Na-H antiporter activity. In summary, increases in luminal flow rate directly increase apical membrane H secretion, possibly by modification of a luminal unstirred layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Sign in / Sign up

Export Citation Format

Share Document