Presence Of TEA Research Articles

Effect of selenium doping on structural and optical properties of SnS:Se thin films by electron beam evaporation method

SnS nanoparticle has been synthesized initially using SnCl 2 · 2H 2 O and Na 2 S · XH 2 O, in the presence of TEA by precipitation method and XRD and FTIR techniques have been used for characterization of the sample. Powder X-ray diffraction studies revealed the particle size to be 48 nm and the pattern represents polycrystalline herzenbergite orthorhombic crystal structure of SnS. The FTIR result also confirmed the SnS at 2354 cm − 1 . Secondly SnS:Se thin films have been deposited on glass substrates by electron beam evaporation technique and the films were annealed at 100 °C and 200 °C for 1 h. The unannealed films are amorphous in nature and the annealed film shows that a sharp crystalline peak is due to SnS. Also a peak is shown at 2 θ = 14.39°, which is due to characteristic peak of SnSe 2 , established by their XRD patterns. The band gap energy ( E g ) was determined from transmission spectra and an optical band gap of E g varies from 1.6 eV to 1.79 eV.

Sequential Bicyclization to the Skeleton of Lennoxamine and Chilenine Using Pd Catalyst

Lennoxamine 1 and chilenine 2 which have an isoindolobenzazepine framework were isolated from Berberis empertrifolia Lam and Berberis darwinii Hook. Although these alkaloids have been known to show weak biological activities, their unique tetracyclic ring system has garnered much attention from synthetic chemists. In the numerous synthetic approaches, the formation of core 7and 5membered rings, actually synthesis of dehydrolennoxamine 3, has been the key target (Figure 1). In this communication we want to suggest an efficient method to the molecule, achieving the formal synthesis. Conversion of 3 to lennoxamine and chilenine has been already achieved. As most of the cyclization methods published until recently have been stepwise approaches, we wished to suggest a sequential bicyclization process from intermediate 4 in one pot. The bicyclization approach has been rare for the synthesis of 3 except radical cascade reaction to lennoxamine 1. The molecule equipped with iodine on aromatic ring, amide, alkyne functional groups was expected to undergo the desired transformation upon treating with Pd. The precursor 4 would be prepared concisely from the known compounds 5 and 6 (Scheme 1). Synthesis of 4 was carried out first by preparation of 7, reaction of 6 with NaOH/MeOH to form a benzoic acid intermediate and the following treatment with SOCl2/CH2Cl2 (48% in two steps). Coupling of 5 and 7 in the presence of TEA in CH2Cl2 afforded the requisite precursor 4 in 66% yield (Scheme 2). Bicyclization of 4 was attempted under the various conditions using palladium catalyst. In the use of K2CO3 as a base, neither Pd(OAc)2 nor other palladium catalysts such as Pd(PPh3)4, Pd(dba)2, Pd(PPh3)2Cl2 with or without ligands provided the desired compounds at all. Decomposition was detected mainly (entry 1). However, the presence of stronger base LiHMDS was found to make the reaction get started (entry 2), and among several palladium reagents, Pd(OAc)2 was the most practical and efficient. Though not much, the addition of LiCl increased the yields moderately (entries 37). The role of LiCl for the increasing the reaction yields cannot be still clearly explained. The best combination, Pd(OAc)2/LiHMDS/LiCl/DMF, was selected to afford 55% yield (entry 4). The mechanism of the transformation is suggested as follow; Oxidative addition and deprotonation to 8, which should induce the proposed bicyclization to 9, was then followed by reductive elimination to afford the desired product 3 (Figure 2). When we applied the same conditions (Table 1, entries 3 Figure 1 Scheme 1

Inhibition of rat carotid body glomus cells TASK-like channels by acute hypoxia is enhanced by chronic intermittent hypoxia

Chronic intermittent hypoxia (CIH), the main feature of obstructive sleep apnea, enhances carotid body (CB) chemosensory responses to acute hypoxia. In spite of that, the primary molecular target of CIH in the CB remains unknown. A key step of the hypoxic response in the CB is the chemoreceptor cell depolarization elicited by the inhibition of K+ channels. Thus, we tested the hypothesis that CIH potentiates the hypoxic-induced depolarization of rat CB chemoreceptor cells by enhancing the inhibition of a background K+ TASK-like channel. Membrane potential, single channel and macroscopic currents were recorded in the presence of TEA and 4-aminopyridine in CB chemoreceptor cells isolated from adult rats exposed to CIH. The CIH treatment did not modify the resting membrane properties but the hypoxic-evoked depolarization increased by 2-fold. In addition, the hypoxic inhibition of the TASK-like channel current was larger and faster in glomus cells from CIH-treated animals. This novel effect of CIH may contribute to explain the enhancing effect of CIH on CB oxygen chemoreception.

Reinvestigation of Drugs and Chemicals as Aquaporin-1 Inhibitors Using Pressure-Induced Hemolysis in Human Erythrocytes

Recently, we have found that pressure-induced hemolysis is enhanced by inhibiting water transport via aquaporin-1 (AQP1), as seen in p-chloromercuribenzoate (pCMB)-treated erythrocytes. So, using this method we reinvestigated the functions as AQP1 inhibitors of drugs and chemicals such as acetazolamide, sodium nitroprusside, tetraethylammonium ions (TEA(+)), and dimethylsulfoxide (DMSO). The values of hemolysis at 200 MPa were almost unaffected by acetazolamide or sodium nitroprusside, decreased by TEA(+), and increased significantly by DMSO. Furthermore, the erythrocytes were exposed to pCMB in the presence of TEA(+) or DMSO. The enhancement effect of pCMB on pressure-induced hemolysis was unaffected by TEA(+) but attenuated by DMSO. Taken together, these results suggest that, of drugs and chemicals examined here, DMSO only is an AQP1 inhibitor, but the effect of DMSO is small compared with pCMB.

Chemo- and biocatalytic strategies to obtain phenylisoserine, a lateral chain of Taxol by asymmetric reduction

Enriched ethyl 3-benzamido-2-hydroxy-3-phenylpropanoate (protected phenylisoserine), the chiral side chain of Taxol, was obtained via asymmetric reduction with transition metal–diphoshine complexes or with whole cells of non-conventional yeasts. Asymmetric hydrogenation was carried out using different approaches: hydrogenation of the tetra-substituted double bond of (E)-1-benzamido-3-ethoxy-3-oxo-1-phenylprop-1-en-2-yl ethyl oxalate 1 with Ir(I)–diphosphine complexes in the presence of TEA, hydrogenation of the carbonyl group of racemic ethyl 3-benzamido-2-oxo-3-phenylpropanoate 2 with Ru(II)–diphoshine complexes in the presence of a Lewis acid and finally a two-step enzymatic transformation of (E)-1-benzamido-3-ethoxy-3-oxo-1-phenylprop-1-en-2-yl ethyl oxalate 1 catalyzed by whole cells of yeasts bearing cell-bound esterases and dehydrogenases.

Copper Seed Layer Deposition by a New Liquid Precursor

AbstractCu(hfac)2(TEA) (hfac = 1,1,1,5,5,5‐hexafluoroacetylacetonate, TEA (triethylamine, N(C2H5)3)) is a new liquid CuII precursor. Using Cu(hfac)2(TEA), we successfully deposit Cu thin films as a seed layer, even at the low deposition temperature of 373 K. To explain this behavior, the bonding status of Cu(hfac)2 in the presence of TEA is determined by density‐functional theory. The theoretical bond length of Cu‐O in Cu(hfac)2 is significantly greater (by 0.06 Å) than that without an adduct ligand.

ATTRACTION OF THE ALMOND MOTH, CADRA CAUTELLA (WALKER), TO READY MADE TEA OR COFFEE: AN ALTERNATION METHOD OF METHYL BROMIDE IN STOREHOUSES OF DATE FRUIT IN EGYPT

Cups of ready made tea or coffee were equally efficient in attracting and killing the almond moths of Cadra cautella, more than water, before egg laying. The ready made coffee was equal to the ready made tea in the attraction power. Baits of tea or coffee attracted significantly more moths than sweet water or tap water. The naturally existing cobweb spiders (Theridiidae) captured the moths during their flight over the tea or coffee baits mainly. The number of moths entangled inside spider webs was greater than those that sank in the tea or coffee solutions. Without the help of these baits, spider webs would have less catch numbers of the moths. So, it is generally recommended that these baits must be at the 4 corners of the store room to facilitate for the web-building spiders spinning their silk crossing the angle of the corner. Non-infested dates accompanying the infested dates continued without infestation in the presence of tea or coffee baits and the existing web-spinning spiders in the microhabitat over the baits. This technique could be used in conjunction with the natural existing web-building spiders that appear in each corner of the store room. The last may be considered as first record or discovery. The application of tea or coffee trap baits with the natural existing cob-web spiders is an excellent example of functional date fruit integrated pest management inside storehouses. This may be a good safe replacement of methyl bromide as well as phosphine tablets.

Effect of black tea (Camellia sinensis) on virulence traits of clinical isolates of Shigella dysenteriae and Escherichia coli EPEC P2 1265 strain

The crude tea polyphenols of regular black tea were investigated in vitro for effect on virulence traits of Shigella dysenteriae and Enteropathogenic Escherichia coli (EPEC P2 1265) strains. Results showed that crude tea polyphenols of black tea significantly increased (p acid un-adapted, tea un-adapted > acid adapted, tea adapted > acid un-adapted, tea-adapted. These results inferred that polyphenolic treatment of bacterial culture disrupts pH hemostasis which caused complete bacterial killing in 120 min when compared to tea-untreated culture where complete killing required 180 min. Serum bactericidal activity was also increased in tea-treated culture of EPEC P2 1265 when 2-h serum treatment caused complete bacterial killing but un-treated cells were killed after 3 h. Also, significant increase (p < 0.05) in enterochelin production was observed when EPEC P2 1265 was grown in presence of tea. The present findings indicate that boiling water black tea extract reduces expression of virulence traits by S. dysenteriae and E. coli EPEC P2 1265 enteropathogen as shown by decreased bacterial survival strategies. The results promote the use of tea extract against multidrug resistant Mycobacterium tuberculosae (MDR-TB) strains and other enteropathogens.

Angiotensin II increases excitability and inhibits a transient potassium current in vagal primary sensory neurons

The octapeptide angiotensin II (ANG II) plays a pivotal role in the maintenance of blood pressure by activating ANG II receptors located in variety of cell types including neurons housed in the central nervous system (CNS) and in the peripheral nervous system (PNS). ANG II (100 nM) blocked spike frequency accommodation (SFA) recorded with whole-cell patch technique in acutely isolated nodose ganglion neurons (NGN) from adult rats. ANG II increased the frequency of action potentials (AP) produced by supramaximal 500 ms depolarizing currents recorded in both tonic (16 Hz vs. 58 Hz, control vs. ANG II perfusion respectively, n=9) and phasic (1Hz vs. 38 Hz, n=13) NGNs. ANG II produced no significant changes in: the resting membrane potential (-51 mV vs. -50 mV, n=65), AP overshoot (46 mV vs. 41 mV, n=25), AP undershoot (-65 mV vs. -61 mV, n=25), AP duration (1 ms vs. 1.2 ms, n=25), and AP threshold (-40 mV vs. -43 mV, n=19). CV-11974 (600 nM), a specific AT1 receptor antagonist, prevented ANG II-evoked changes SFA (n=10). ANG II (100 nM) had no significant effect on total outward potassium current (I(K)) but inhibited a fast activating and fast inactivating I(K) recorded in the presence of TEA. A kinetically similar I(K) was also inhibited by 4-AP (3mM). In phasic NGNs, 4-AP occluded the effects of 100 nM ANG II on SFA. Our results indicate that ANG II can block an A-type of I(K) and that this effect may underlie the ANG II-mediated change in SFA.

Effect of green and black teas ( Camellia sinensis L.) on the characteristic microflora of yogurt during fermentation and refrigerated storage

The effect of tea on the fermentation and survival of yogurt microorganisms was studied. Green and black teas were added to milk at the beginning of fermentation. Acidity of yogurt products and survival of their microflora were studied during 42 days at 4 °C. Results showed that the presence of tea did not significantly ( P < 0.05) influence the yogurt characteristic microorganisms. HPLC studies demonstrated that yogurt bacteria did not affect tea catechins when they were incubated together for 48 h. Indeed, all five products reached about 10 9 CFU/ml after 6 h of fermentation. Viability during 6 weeks storage at 4 °C varied very little (8.35 < log CFU/ml < 8.65). Similarly, green and black teas had no effect on lactic acid levels of the final products (after 6 weeks of storage, acidity remained above 80 °D). According to these findings, addition of teas or tea catechins to yogurt can be recommended to take advantage of their beneficial properties on human health attributed to their antioxidant and antimicrobial activities.

The Synthesis of 1,4‐Bis[N‐(4/6‐Substituted Benzothiazole‐2‐yl)‐N′‐Glycosylguanidino]Benzenes

AbstractThe starting material O‐protected glycosyl isothiocyanate (1˜3) was refluxed with 1,4‐diaminobenzene in CHCl3 under nitrogen atmosphere to give 1,4‐bis(N‐glycosyl)thioureidobenzene (4˜6). Then 1,4‐bis[N‐(4/6‐substituted benzothiazole‐2‐yl)‐N′‐glycosylguanidino]benzenes (8a˜8e, 9a˜9e, 10a˜10e) were obtained in good yield by reaction of compounds (4˜6) with 2‐amino‐4/6‐benzothizoles (7a˜7e) and HgCl2 in the presence of TEA in DMF. The structures of all 18 new compounds were confirmed by IR, 1H NMR, LC‐MS and elemental analysis. The bioactivity of anti‐HIV‐1 protease (HIV‐1 PR) and against angiotensin converting enzyme (ACE) have been evaluated.

Kinetics controlled growth of quasi-spherical ZnO single crystal in homogeneous solutions

Abstract Quasi-spherical ZnO single crystal particles were synthesized in Zn 2+ –TEA–IPA solution. The kinetics controlled growth of ZnO single crystal follows a multi-step mechanism. Firstly, polycrystalline ZnO forms in hot zinc ion solution in the presence of TEA. Next, polycrystalline ZnO dissolves and growth unit, Zn(OH) 4 2+ , appears. Thirdly, ZnO nanoparticles are obtained by dissociating and dehydrating Zn(OH) 4 2+ . Finally, the orientated aggregation of ZnO nanoparticles leads to formation of quasi-spherical ZnO microcrystals. The appearance of ZnO nanoparticles and the binding of TEA molecules on ZnO positive polars are demonstrated key factors for isotropic aggregation of ZnO quasi-spheres. ZnO quasi-spheres can emit strong ultraviolet light and weak blue light, which arise from the near band edge emission and structural defects, repectively.

Synthesis of Fused [5,5]‐1,2,4‐Triazoles via Tandem Thioimidate Cyclopropane Rearrangement—Cyclization.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

The functional difference between transient and sustained K + currents on the action potentials in tetrodotoxin-resistant adult rat trigeminal ganglion neurons

To determine whether there is a difference between a transient K + current ( I A) and a sustained K + current ( I K) regarding the neuronal function in small-diameter adult rat trigeminal ganglion (TG) neurons, which were insensitive to tetrodotoxin (TTX, 1 μM), we performed two different types of experiments. Primary cultures of dissociated TG neurons were prepared, and electrophysiological recordings were performed with the whole-cell configuration using the patch-clamp technique. In the voltage-clamp mode, two distinct K + current components, ( I A) and ( I K), were identified, and two different components (59.5% and 96.3%) of I K to the total K + current were observed at a + 50 mV step-pulse. The IC 50 value for 4-aminoprydine (4-AP, 0.05–50 mM), which inhibited the I A by 50%, was 0.7 mM. That for tetraethylammonium (TEA, 0.02–20 mM) to inhibit 50% of I K was 1.5 mM. In the current-clamp mode, we used 0.5 mM 4-AP and 2 mM TEA at each concentration nearly equal to the IC 50 value. Irrespective of the absence or presence of TEA (2 mM), 0.5 mM 4-AP application increased the number of action potentials due to the decreased duration of the depolarization phase (DDP). TEA in the presence and absence of 4-AP prolonged the duration of action potentials as well as the duration of repolarization phase (DRP). These results suggested that I A and I K had independent effects regulating the intrinsic firing properties of the action potential number and timing, respectively, in adult rat TTX-R TG neurons.

The endothelium-derived hyperpolarising factor (EDHF) in isolated bovine choroidal arteries

The present study reports of an endothelium-dependent and NO- and prostanoid-independent relaxation in isolated choroidal arteries, and evaluates the hypothesis of an endothelium-derived hyperpolarising factor (EDHF) playing a role in the choroidal circulation. Choroidal arteries were isolated from bovine eyes and mounted in a small vessel wire-myograph for isometric tension recording. Concentration-response curves for acetylcholine (0.1 nM–10 μM) were constructed in isolated choroidal arteries contracted with 10 μM norepinephrine. Acetylcholine induced a concentration-dependent relaxation in the choroidal arteries. The presence of the NO-synthase inhibitor L-NA and the cyclo-oxygenase inhibitor indomethacin only had a limited effect on this relaxation. All further experiments were performed in the presence of L-NA and indomethacin, in order to study the NO- and prostanoid-independent part of the acetylcholine-relaxations. Both removal of the vascular endothelium or the presence of an increased K + concentration in the organ bath abolished the NO- and prostanoid-independent part of the acetylcholine-relaxations. The presence of TEA, a rather non-specific K + channel blocker, significantly reduced the acetylcholine-relaxations. Simultaneous application of apamin (an inhibitor of small-conductance Ca 2+-activated K + channels) and charybdotoxin (an inhibitor of intermediate- and large-conductance Ca 2+-activated K + channels) abolished the acetylcholine-induced relaxation and even resulted in a concentration-dependent contraction. Transmembrane potential recordings in isolated choroidal arteries revealed a clear membrane hyperpolarisation in the vascular smooth muscle cells of isolated choroidal arteries. It was therefore concluded that the acetylcholine-induced relaxation of choroidal arteries in the presence of NO-synthase and cyclo-oxygenase inhibitors is mediated by an endothelium-derived hyperpolarising factor. This EDHF seems to be of more importance than endothelium-derived NO or prostanoids.

Zinc-Nickel Alloy Electrodeposition – Influence of Triethanolamine

Compared to pure zinc plating, zinc alloys provide several advantages. A zinc alloy generally offers superior sacrificial protection to steel since it corrodes more slowly than pure zinc. A search for a non-cyanide zinc plating bath resulted on the development of a zinc nickel sulphamate bath. To obtain better quality zinc-nickel deposits, triethanolamine was added to the bath. In this paper the influence of triethanolamine in zinc-nickel plating from sulphamate bath has been investigated through current efficiency measurements, cyclic voltammetry, scanning electron microscope, and X-ray diffraction techniques. In the presence of triethanolamine in the zinc-nickel sulphamate bath the current efficiency of alloy deposition increased to a maximum of 99% at the current density of 1.5 Adm -2 and thereafter decreased. TEA adsorbed on the electrode surface obeying Henry’s isotherm. On mild steel surfaces, uniform smooth slate gray deposit with smaller crystallites was produced, in presence of TEA in solution, and the electrodeposits exhibited additional Zn(OH) 2 and γ-Ni 3Zn 22 phases. Hydrogen evolution was suppressed by TEA and thereby current efficiency is increased for alloy deposition.

Synthesis of Fused [5,5]‐1,2,4‐Triazoles via Tandem Thioimidate Cyclopropane Rearrangement–Cyclization

The synthesis of fused [5,5]‐1,2,4‐triazoles via a tandem cyclopropane rearrangement–cyclization sequence is described. Optimization of the cyclization reaction was achieved thermally using iPrOH as the solvent in the presence of TEA. This method was applied to the preparation of 3‐substituted‐7‐aryl‐pyrrolo‐1,2,4‐triazoles in good to excellent yields.

Nucleophilic α‐Addition to β‐Nitroacrylates: Application to the Synthesis of α‐Thioacrylates.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Nucleophilic α-addition to β-nitroacrylates: application to the synthesis of α-thioacrylates

The α-addition of alkyl or aryl thionucleophiles to β-nitro-α,β-unsaturated alkenoates in THF in the presence of TEA or DBU gave access to the α-thio-α,β-unsaturated alkenoates. The reaction occurred via formation of β-nitro-α-thioalkanoates and concomitant elimination of nitrous acid from the α-adducts.

The Interaction of an Impermeant Cation with the Sheep Cardiac RyR Channel Alters Ryanoid Association

In previous studies, we have demonstrated that the interaction of ryanoids with the sarcoplasmic reticulum Ca(2+)-release channel [ryanodine receptor (RyR)] incorporated into planar lipid bilayers reduced the effectiveness of tetraethylammonium (TEA(+)) as a blocker of K(+) translocation (J Gen Physiol 117: 385-393, 2001). In the current study, we investigated both the effect of TEA(+) on [(3)H]ryanodine binding and the actions of this impermeant cation on the interaction of the reversible ryanoid 21-amino-9alpha-hydroxyryanodine with individual, voltage-clamped RyR channels. A dose-dependent inhibition of [(3)H]ryanodine binding was observed in the presence of TEA(+), suggesting that the cation and alkaloid compete for access to a common site of interaction. Single channel studies gave further insights into the mechanism of the competition between the two classes of ligands. TEA(+) decreases the association rate of 21-amino-9alpha-hydroxyryanodine with its receptor, whereas the dissociation rate of the ryanoid from the channel was unaffected. Our results demonstrate that TEA(+) inhibits both K(+) translocation through RyR, and ryanoid interaction at the high affinity ryanodine site on the channel. These actions involve binding of TEA(+) to different, but weakly interacting, sites in the RyR channel.