Phenomenon Of Synergism Research Articles

Efficiency of bubble contact devices and the phenomenon of synergism in mass transfer vessels

The design and efficiency of multilayer packets of downcomerless grid and tube-grid trays were evaluated against directed-jet and valve trays in the distillation of a model mixture of benzene and toluene in a 1000-mm diameter column. The trays were tested at infinite reflux. Column flooding was detected by a sharp increase in pressure and a decrease in temperature in the column bottom and by a decrease in separating capacity. Quality of feed, reflux, and distillate was monitored chromatographically. Column operating efficiency was evaluated on the basis of the height equivalent to a theoretical plate. The highest efficiencies and capacities were demonstrated by the directed-jet and downcomerless tube-grid trays. The latter trays can also be used for removal and supply of heat for distillation columns. Statistical and hydraulic data are cited for the investigation.

Mechanistic aspects of the thermal stabilisation of PVC by organotin compounds

AbstractWhen subjected to heat and mechanical shear PVC decomposes via the elimination of HCl. This process is controlled most efficiently by the use of organotin stabilisers. This review outlines the basic degradation/stabilisation mechanisms which are involved in these processes. The organotin compounds of most commercial significance receive particular attention. Model compound studies which highlight potential stabilisation mechanisms are discussed but emphasis is placed on in‐situ studies which are much more realistic. Finally the phenomenon of synergism is discussed with reference to conventional alkyltin and the more novel estertin compounds.

The cellulase of Penicillium pinophilum. Synergism between enzyme components in solubilizing cellulose with special reference to the involvement of two immunologically distinct cellobiohydrolases.

Two immunologically unrelated cellobiohydrolases (I and II), isolated from the extracellular cellulase system elaborated by the fungus Penicillum pinophilum, acted in synergism to solubilize the microcrystalline cellulose Avicel; the ratio of the two enzymes for maximum rate of attack was approx. 1:1. A hypothesis to explain the phenomenon of synergism between two endwise-acting cellobiohydrolases is presented. It is suggested that the cellobiohydrolases may be two stereospecific enzymes concerned with the hydrolysis of the two different configurations of non-reducing end groups that would exist in cellulose. Only one type of cellobiohydrolase has been isolated so far from the cellulases of the fungi Fusarium solani and Trichoderma koningii. Only cellobiohydrolase II of P. pinophilum acted synergistically with the cellobiohydrolase of the fungi T. koningii or F. solani to solubilize Avicel. Cellobiohydrolase II showed no capacity for co-operating with the endo-1,4-beta-glucanase of T. koningii or F. solani to solubilize crystalline cellulose, but cellobiohydrolase I did. These results are discussed in the context of the hypothesis presented.

Coordinate regulation of unsaturated phospholipid, RNA, and protein synthesis in Mycoplasma capricolum by cholesterol.

The effect of cholesterol, epicoprostanol, and phosphatidylcholine on phospholipid, RNA, and protein synthesis was investigated in the sterol auxotroph Mycoplasma capricolum. Cells growing poorly on lanosterol were stimulated to grow more rapidly by supplementing the medium with either 2 micrograms of cholesterol or 2.2 micrograms of egg phosphatidylcholine per ml. In such cells cholesterol caused a sequential stimulation of phospholipid, RNA, and protein synthesis. Enhanced oleate incorporation into phospholipid occurred early; the rates of RNA and protein synthesis increased later. In cells supplemented with phosphatidylcholine only RNA and protein syntheses were enhanced. The addition of 2 micrograms of epicoprostanol per ml to cells growing on lanosterol promptly inhibited the rate of unsaturated phospholipid synthesis and subsequently the rate of growth. Inhibition of both processes was relieved by supplying 2 micrograms of cholesterol or 2.2 micrograms of phosphatidylcholine per ml along with the inhibitory sterol. The results suggest that cholesterol in small amounts exerts a positive regulatory effect and epicoprostanol exerts a negative one on unsaturated phospholipid synthesis and, in turn, that RNA and protein synthesis are coordinately controlled with phospholipid synthesis. The previously reported phenomenon of sterol synergism and the postulated novel role of sterols in membranes.

Ethidium bromide changes the nuclease-sensitive DNA binding sites of the antitumor drug cis-diamminedichloroplatinum(II).

Exonuclease III has been shown previously to reveal the binding sites of the antitumor drug cis-diamminedichloroplatinum(II) on DNA. Pretreatment of the same DNA with the intercalator ethidium bromide causes new platinum binding sites to be detected by the exonuclease III method. In particular, a 5'd(G6-D-G2)3' sequence in a 165-base-pair restriction fragment of plasmid pBR322 becomes a preferred site for exonuclease III-detectable cis-diamminedichloroplatinum(II)binding. This switching of nuclease-sensitive platinum binding to new sites by the influence of another drug, ethidium bromide, offers an explantation at the molecular level for the phenomenon of synergism in combination chemotherapy.

A possible mechanism to explain the synergistic effects exhibited by mixtures of alkyltin mercaptoesters as stabilisers for PVC

The phenomenon of synergism observed with mixtures of mono- and dialkyltin stabilisers for PVC has been recognised and exploited for many years, but remains largely unexplained. Whilst a similar effect in mixed metal (Ba/Cd or Ca/Zn) carboxylate stabilisers has been explained, mechanistic studies of the organotin systems have not appeared. Infra-red spectroscopy has now been used to study the Cl/mercaptoester exchange equilibria of alkyltin mercaptoester (isooctylthioglycollate) chlorine compounds which are undoubtedly produced when the organotin mercaptoesters act as PVC stabilisers. The exchange process is shown to be facile, even at ambient temperatures, and a regenerative mechanism, based on these observations, is proposed to explain the synergistic effect.

Mechanism of the synergistic action of mixtures of metal dithiocarbamates with thiuram bisulfide in the inhibition of the oxidation of hydrocarbons

1. A phenomenon of synergism has been established in the inhibition of the initiated oxidation (75°C) and autooxidation (120°C) of ethylbenzene by mixtures of copper and nickel bis(N,N-diethyldithiocarbamates) with thiuram disulfide (TDS). 2. The synergistic effect in such systems is due to the regeneration of the dithiocarbamates of copper and nickel under the action of TDS.

Comparative modification of insecticide‐resistance spectrum of Culex pipiens fatigans wied. By selection with temephos and temephos/synergist combinations

AbstractThe evolution of strong organophosphorus multiresistance, suppressible by S,S,S‐tributyl phosphorotrithioate (TBPT), in a California strain of Culex pipiens fatigans was examined by further selection with temephos, alone and in combination with the synergists TBPT or piperonyl butoxide (PB). Selection by temephos and temephos + PB increased resistance to higher levels. However, selection by temephos + TBPT virtually abolished TBPT‐suppressible resistance while preventing the emergence of significant alternative resistance mechanisms. The phenomenon of synergism may enable the extended use of an insecticide where alternative resistance mechanisms are either absent or of low efficiency in the target population.

The phenomenon of synergism in the field of chemistry

The phenomenon of synergism in the field of chemistry

Drug interaction.

Years ago, the practice of medicine required much artful prescribing of multiple ingredients to be skillfully compounded specifically for individual patients. At least one ingredient was generally selected to attack each symptom. The phenomenon of synergism was often discussed and sought. Antagonism was recognized in the form of "antidotes," and some ingredients were added solely to control an undesired action while retaining the beneficial effect of other drugs. But there was no real understanding of how drugs interacted.Today, more of our drugs attack disease by way of its etiology or the basic mechanism of its pathophysiology, so that it . . .

The Synergism of Diltiazem and Nifedipine in their Antihypertensive Functions in the Animal Model and the Case of Coadministration of Ketotifen Fumerate and Potassium Nitrate with them

An in vivo study has been carried out to evaluate the synergism of diltiazem and nifedipine on the antihypertensive activity and the effect of ketotifen fumerate and potassium nitrate on this phenomenon of synergism in rabbit. It has been found that the lowering of blood pressure by concurrent administration of diltiazem and nifedipine was not equal to the sum of lowering of blood pressure by individual drug. Concurrent administration of ketotifen fumerate and potassium nitrate with diltiazem or with nifedipine did not make a significant change on the antihypertensive activity of diltiazem or nifedipine. Further considerations and monitoring are to be practiced during concurrent therapy of diltiazem and nifedipine to avoid untoward pharmacological and therapeutic actions related to druginteractions but coadministration of ketotifen fumerate and potassium nitrate with either diltiazem or nifedipine might be regarded as safe and effective. 
 
 Keywords: in vivo, antihypertensive activity, nifedipine, diltiazem, ketotifen fumerate, potassium nitrate, coadministration. 
 
 J. bio-sci. 14: 61-67, 2006

64Cu solvent extraction studies — adducts of copper (II) β-diketonates and their role in the synergistic extraction of copper

Tracer extraction studies have been carried out on the system 64CuHAS, where HA = thenoyltrifluoroacetone (HTTA), hexafluoroacetylacetone (HHFA), trifluoroacetylacetone (HTFA) and acetylacetone (H acac); S = quinoline, iso-quinoline and tri-n-octyl phosphine oxide (TOPO). An equilibrium constant has also been measured for the formation of the extracted species Cu (TTA) 2·TOPO. This work supports the proposal that the phenomenon of synergism involves both the stability and the solubility of binary and ternary complexes.

Metal complexes in solvent extraction studies—III Preparation and investigation of binary and ternary complexes

Some ternary complexes of the type M(chelate) 2S x [M = UO 2 2+, Cu 2+, Zn 2+, Ni 2+, Co 2+, chelate = TTA (thenoyltrifluoroacetone anion), S = TBP (tri-n-butyl phosphate), TBEP (tri-n-butoxyethyl phosphate, TOPO (tri-n-octyl phosphine oxide), 4-me-py (4-methyl pyridine), TPPO (tri-phenyl-phosphine oxide)] have been prepared and investigated. Preliminary work has also been carried out with HFacac (hexafluoroacetylacetone anion), TFacac (trifluoroacetylacetone anion) and acac (acetylacetone anion) as chelates. The compounds Zn(HFacac) 2· xH 2O ( x = 1 and 2), Zn-(HFacac) 2(TOPO) 2, Cu(HFacac) 2TOPO, Co(acac) 2(4-me-py) 2, UO 2(acac) 2·4-me-py and UO 2(acac) 2 (TPPO) 3 have also been isolated. Solvent extraction studies show that the synergistic extraction of 65Zn depends upon the nature of the chelate and of S. It is suggested that the phenomenon of synergism involves both the stability of M(chelate) 2· xH 2O and M(chelate) 2S x and further, that the bonding of S, which is directly to the metal, is weak and comparable to solvation or adduct formation.

Metal complexes involved in solvent extraction and their role in the synergistic effect

Solid ternary complexes of the type M(TTA) 2·TOPO (M = Zn 2+ and Cu 2+, TTA = thenoyltrifluoroacetone anion and TOPO = tri-n-octyl phosphine oxide) have been prepared and investigated. The phosphorus nuclear magnetic resonance method has been used to determine the equilibrium constant of the reaction Zn(TTA) 2 (org.) + TOPO (org.) = Zn(TTA) 2·TOPO(org.). This was found to be approximately 10 1/mole in anhydrous carbon tetrachloride medium. It was also shown that in the same medium, the less basic TBEP (tri-n-butoxyethyl phosphate) did not coordinate with Zn(TTA) 2 to any measurable extent. In fact, the corresponding ternary complexes M(TTA) 2·TBEP could not be isolated. Proton magnetic resonance studies also afford evidence for the reaction: Zn(TTA) 2·2H 2O + TOPO = Zn(TTA) 2·TOPO + 2H 2O in carbon tetrachloride medium. It is suggested that the phenomenon of synergism may be due to the enhanced solubility (in the organic phase) of neutral metal chelates caused by adduct formation with ligands such as TOPO.

Neuere Untersuchungen über Koazervate von Seifen

A survey has been given of the experiments on the influence of organic molecules on soap coacervates. Especially the importance of these kinds of investigations for biology has been underlined. The hypothesis was framed that the biological activity of many substances may be understood from a study of the distribution of these substances on the various possible places in a lipoid system. Not only within the organism but also within the cell an unequal distribution of an added organic compound on the different parts plays an important part. The distribution of one substance may — in some cases at least — be strongly influenced by the addition of a second substance. Part of the phenomena of antagonism and synergism may find an explanation along these lines of thought.

Synergism between pituitary follicle stimulating hormone (FSH) and human chorionic gonadotropin (HCG).

IT HAS been known for years that the gonadotropic action in female rats of pituitary follicle stimulating hormone is augmented by simultaneous administration of interstitial cell stimulating substances, such as pituitary ICSH (LH, Fevold et al., 1931) or human chorionic gonadotropin (Evans et al., 1931). As FSH was more completely purified the same synergic reaction continued to be demonstrable. Some question arose, however, as to the degree of limitation of FSH effects in the complete absence of ICSH. It has become widely accepted that FSH alone cannot produce large follicles capable of producing enough estrogen to bring animals into estrus. As regards the phenomenon of synergism in the male it was reported (Evans et al., 1934, 1937; Greep et al., 1936) that the two types of hormone acted synergically also in the male. When FSH was purified sufficiently to meet the chemists’ standards for physico-chemical purity: electrophoresis, diffusion and ultra-centrifugation (Li, Simpson, and Evans, 1949; Li, 1949)...

A Quantitative Study of the Phenomena of Synergism: Potentiation of Hypnotic Action in Mice. (Compt. Rend., vol. cci, pp. 796–7, 1935.) Olszycka, L.

<i>A Quantitative Study of the Phenomena of Synergism: Potentiation of Hypnotic Action in Mice.</i> (<i>Compt. Rend., vol. cci, pp.</i> 796–7, 1935.) <i>Olszycka, L.</i>

THE RECOGNITION AND COMPARISON OF PROLAN AND PROLAN-LIKE SUBSTANCES

The synergism phenomenon has made possible the recognition of substances, which we have called "prolan-like," in a wide variety of conditions. Indeed, it has been possible to demonstrate a prolan-like material in the urine of normal men. The method has shown a wide distribution of prolan-like substances in sera and urines of non-primates without demonstrating, however, significant difference in the reactions secured from pregnant as contrasted with non-pregnant states, or in males as contrasted with females. The synergism phenomenon with pregnancy prolan can also be shown in the increased development of the seminal vesicles of immature male rats. However, such males cannot be advantageously employed in the detection of prolan-like gonadotropic substances occurring in the blood and urine in conditions other than pregnancy, for the prolan-like substances usually do not effect appreciable development of the seminal vesicles.

Peculiarities of the Prolan-like Substance in Urine in a Case of Embryonal Carcinoma of the Testis

Extensive biological study has been made of the gonadotropic substance, prolan, which occurs in the urine of pregnant women. Unlike the gonadotropic hormone occurring in the anterior hypophysis itself, prolan even when concentrated, is sharply limited1 in its capacity to cause development of the ovaries in immature rats. When combined with a special synergic principle of the anterior hypophysis,2, 3 a marked augmentation of the ovary weights occurs. The gonadotropic effects are then fully equal to those produced by the most potent extracts of the gland itself.In the study of the synergism phenomenon with prolan-like substances from sources other than pregnancy, the urines of several types of malignancy were investigated. Among these cases was an individual suffering from embryonal carcinoma of the testis with generalized metastases. Ferguson4 has shown the remarkably high prolan unitage in the urine of such cases.The urine in question had an extraordinarily high unitage (50,000 mouse units per liter). In ...