Lecular Weight Research Articles

THE USE OF BIO-MOLECULAR SUBSTANCE OF MARINE BIOTA AS AN ALTERNATIVE EARLY INDICATOR OF OIL POLLUTED ENVIRONMENT: A NEW APPROACH FOR MONITORING CONSIDERATION

THE USE OF BIO-MOLECULAR SUBSTANCE OF MARINE BIOTA AS AN ALTERNATIVE EARLY INDICATOR OF OIL POLLUTED ENVIRONMENT: A NEW APPROACH FOR MONITORING CONSIDERATION

EFFECT OF CHITOSAN ON PLANT GROWTH, FLOWERING AND CORMS YIELD OF POTTED

The research was aimed at determining the influence of chitosan with different mo lecular weights on the growth and yield of flowers and corms of ‘Gompey’ freesia cultivated in pots. Freesia corms were soaked for 20 minutes in 0.5% chitosan solutions with low molecular weight (2 kDa), medium molecular weight (50 kDa) and high molecular weight (970 kDa). The average deacetylation level of the chitosans used was 85%. The plants were cultivated under controlled conditions (18/16 °C day/ night, relative air humidity of 60%, quantum irradiance of 90 μmol∙m -2 ∙s -1 with a light/ dark cycle of 14/8 hours). The research results obtained have shown that chitosan is used as a biostimulator in the cultivation of potted freesia. Regardless of the molecular weight of the compound, the chitosan-treated plants had more leaves and shoots, flowered earlier, formed more flowers and corms . The application of medium- and high-molecular-weight chitosan resulted in higher plants with a higher relative chlorophyll content (SPAD). The highest increase in the corm weight was observed as a result of treating plants with high-molecular-weight chitosan. No chitosan influence on the length of the main inflorescence shoot or the inflorescence length was observed.

Biodegradation of Polycyclic Aromatic Hydrocarbons by Associated Microbes from Abattoir Wastes in the Niger Delta, Nigeria

The biodegradation of polycyclic aro matic hydrocarbons by associated microorganisms were studied. Soil and waste water samp les were co llected fro m four abattoirs located at Egbu and Ogbe in Imo state, Trans-Amad i and Ahoada in Rivers State. Likewise, surface water and sediment samples fro m Otamiri River and Og inigba Creek adjoined to Egbu and Trans-Amadi abattoirs, respectively were co llected using standard methods. The ability of hydrocarbon utilizing bacteria and fungi to biodegrade polycyclic aro matic hydrocarbons (PAHs) was carried out by growing isolates in a mineral salt broth amended with PAHs. Levels of polycyclic aro matic hydrocarbons (PAHs) left after incubation were determined using Gas chromatographic method. Results showed that soil samples fro m various abattoirs had high concentration of PAHs which ranged fro m 0.176 mg/kg fro m Ahoada abattoir to 2.44 mg/ kg fro m Egbu abattoir. In a 21-day biodegradation test, there was a drop in the init ial concentration of PAHs used as control fro m 0.03 mg/l to 0.024 mg/l. Test results showed decrease in the concentration of PAHs with increase in exposure time. There was observable loss of low molecular weight PAHs than the high mo lecular weight co mponents. It is evident fro m the study that both mixed cultures of bacteria and fungi can biodegrade polycyclic aro matic hydrocarbons. Results fro m this study have shown that abattoir wastes have high pollution strength and thus should be treated before being discharged into the environment. Thus bacteria and fungi isolated fro m and within the abattoirs are potential agents of remedying environ ments impacted by polycyclic aro mat ic hydrocarbons (PAHs).

Purification and Characterization of Chitinase Produced by Endophytic <i>St</i><i>re</i><i>ptomyceshygroscopicus</i><i> </i>Against Some Phytopathogens

Microorganisms, wh ich secret a co mplex o f mycolytic enzy mes are considered to be possible bio logical control agents of plant d iseases. Since Ch itinases are digestive enzy mes that break down glycosidic bonds in chit in. In this present study, an industrial en zy me chitinase produced by endophyticStreptomyceswas purified and its antifungal act ivity was investigated against phytopathogens i.e. Rhizoctoniasolani,Fusariumoxysporum, Alternaria alternate, Aspergillusniger, Aspergillusflavus, Sclerotiniascleotiorum, Phytophthoraparasiticaand Botrytis cinerea.A chitinasewas produced byendophyticStreptomyceshygroscopicus in cultures containing chitin as the sole substrate that degrade chitin in 0.9 mm zone of clearance. The purification steps included ammoniu m sulfate precip itation, with colu mns of DEA E-Sepharose anion exchange chromatography and Sephacryl S-400 high resolution gel chro matography. The method gave a 5.4 fold increase of the specific activ ity and had a y ield of 18%. The mo lecular weight of the chit inase was found to be around 80.8, 78 and 76 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PA GE) technique. Chit inase was optimally active at pH of 6.0 to7.0 and at 30℃. The ch itanase were found to inhibit the growth of all phytopathogenic fungi.

Glyco-silicon Functional Materials as Anti-influenza Virus Agents

This review shows introduction of glycoclusters using carbosilanes as core scaffolds, preparations of glyco- clusters and their excellent properties as well as functions. Since a dendrimer has unique advantages such as single mo- lecular weight, regularity of structure and easy control of shape and size, dendrimers are utilized in various research areas. Results of syntheses and biological evaluations of the carbosilane dendrimers having carbohydrate moieties for influenza viruses are presented.

Mechanical and Gas Barrier Properties of Polypropylene Layered Silicate Nanocomposites: A Review

Polypropylene owing to its apolar nature suffers from compatibility problems with clay, which is partially polar even after the surface modification with alkyl ammonium ions. To circumvent this limitation, polypropylene nanocompo- sites have been synthesized by using two methodologies: a) partial polarization of the matrix by the addition of low mo- lecular weight compatibilizer which owing to its amphiphilic nature acts towards compatibilizing the polymer and inor- ganic phases and b) by completely organophilizing the clay surface by using filler surface modification with long alkyl chains and with higher chain density. The addition of compatibilizer leads to better filler delamination and better me- chanical performance, however, the modulus decreases after a certain extent of compatibilizer owing to plasticization of matrix. The permeation properties were observed to be affected negatively owing to mismatch of the polar compatibilizer chains with apolar surface modification chains. The second methodology, on the other hand, leads to simultaneous im- provement of mechanical and gas barrier properties. Better organophilization of the filler surface reduces the attractive forces between the platelets further and increases their potential of exfoliation in the polymer matrix. Other advanced sur- face modifications dealing with chemical reactions on the surface of the filler have also been reported to increase the basal plane spacing.

Oxidation, Chain Scission and Cross-Linking Studies of Polysiloxanes upon Ageings

The comparison between physical properties and chemical structures of several polysiloxanes was studied at initial state and upon ageings. Techniques such as densimetry, gel permeation chromatography, FTIR spectroscopy, thermogravim- etric analysis coupled with IR spectroscopy and the new tool photo-DSC were used to give assessments of average mo- lecular weight, chemical evolution, cristallinity and thermal stability. Different types of ageing such as thermal ageing (60?C and 100?C), photo-ageing and acid vapour ageing were performed. After ageing we observed an evolution of chemical structures and physical properties for all samples. The main pathway of degradation is given for each sample. It results in oxidation, chain scission or cross-linking. Cross-linking levels are dependant on the type of ageing, the chemical structure and the initial rate of cristallinity. Cross-linking reactions are favoured after photo-ageing. Oxidation is higher for polysiloxane with aliphatic carbon chain.

Investigation of Nanoemulsion System for Transdermal Delivery of Domperidone: Ex-vivo and in vivo Studies

The aim of the present study was to investigate the nanoemulsion system for enhanced percutaneous penetration of domperi- done. Pseudoternary phase diagrams were constructed in order to optimize the surfactant, cosurfactant and surfactant: cosurfactant weight ratios (Smix). Nine nanoemulsion formulations were selected, characterized and their ex-vivo permeation studies using rat skin were per- formed. The nanoemulsion formulations had small droplet size (<90 nm), uniform size distribution (PI, < 0.2) and low viscosity (<160 mP). The results demonstrated that the droplet size and viscosity of nanoemulsion decreased following decrease in the concentration of polysorbate 20, whereas transdermal flux was increased. The optimized formulation NE-B1, which contained oleic acid (4 % w/w), polysorbate 20 (10 % w/w), diethylene glycol monoethyl ether (20 % w/w) and water (64 % w/w) showed significant increase (P < 0.01) in the transdermal flux (169.32 ± 8.33 � g.h -1 cm -2 ). The in vivo studies revealed a 3.5 fold increase in relative bioavailability through transdermal application of NE-B1 formulation compared to oral drug suspension. Moreover, the effective drug plasma concentration was maintained for 16 hour after the transdermal application indicated that the developed nanoemulsion systems could be a promising carrier for the transdermal delivery of domperidone for prolonged period. Microemulsions are quaternary systems composed of an oil phase, a water phase, surfactant frequently in combination with cosurfactant (1-3). These spontaneously formed systems possess specific physicochemical properties such as transparency, optical isotropy, low viscosity and thermodynamic stability. In stable mi- croemulsion, droplet diameter is usually within the range of 10-100 nm (100-1000 A°), and therefore these systems are also termed as nanoemulsions (NE) (4). Due to their unique physicochemical properties, NE offer advantages over traditional topical and trans- dermal drug delivery formulations. Many studies have shown that NE formulations possess improved transdermal and dermal delivery properties both in vitro (5-17), as well as in vivo (18-22). The high solubilizing capacity of NE enables them to increase the solubility of poorly water-soluble drugs. Both, increase in solute concentra- tion and the tendency of the drug to favor partitioning into the stra- tum corneum make NE a useful vehicle to enhance transdermal drug permeability (23). As demonstrated by a recent publication (18), the transdermal permeation rate of a lipophilic drug significantly increased from NE as compared to macroemulsions. In macroemulsions the free mobil- ity of the active material between the internal (disperse) phase to the external (continuous) phase within the structure of the formu- lated system is limited due to the strong interactions between the surfactants that form tight interfacial film. In NE, the co-surfactant lowers the interfacial tension of the surfactant film, resulting in a more flexible and dynamic layer (3,14). The drug in this energy- rich system can diffuse across the flexible interfacial surfactant film, a thermodynamic process that increases partitioning and diffu- sion into the stratum corneum. This article is intended to demonstrate the feasibility of new o/w NE system for transdermal delivery of domperidone. Domperi- done is a dopamine (D2 receptor) antagonist with predominant peripheral activity. It is clinically effective in conditions such as diabetic gastroparesis, chronic dyspepsia, pediatric vomiting, cancer chemotherapy induced nausea and emesis (24). Owing to its high portion of hepatic first pass metabolism (~85 %) (25), its low mo- lecular weight (426 Da), its moderate lipophilicity (Log P, 3.9) as

Influence of long-chain branching on time-pressure and time-temperature shift factors for polystyrene and polyethylene

Rheological characteriza- tions were carried out for two poly- styrenes. One was a linear polymer with Mw=222,000 g/mol and Mw/Mn=2, while the other was a randomly branched polystyrene with Mw=678,000 g/mol and a broad mo- lecular weight distribution. Experi- ments performed included oscillatory shear to determine the storage and loss moduli as functions of frequency and temperature, viscosity as a function of shear rate and pressure, and multi- angle light scattering to determine the radius of gyration as a function of molecular weight. The presence of branching in one sample was clearly revealed by the radius of gyration and the low-frequency portion of the complex viscosity curve. Data are also shown for three polyethylene copoly- mers, one (LLDPE) made using a Ziegler catalyst and two made using metallocene catalysts, one (BmPE) with and one (LmPE) without long- chain branching (LCB). While the distribution of comonomer is known to be much more uniform in LmPE than in LLDPE, the pressure shift factors were the same for these two polymers. The pressure and tempera- ture shift factors of the two polysty- renes were identical, but, in the case of polyethylene, the presence of a small amount of LCB in the BmPE had a definite effect on the shift factors. These observations are discussed in terms of the relative roles of free volume and thermal activation in the effects of temperature and pressure.

Determining the Molecular Weight Distribution of Cotton Cellulose: A New GPC Solvent

Dimethylimidazolidinone/lithium chloride (DMI/LiCL) is shown to be an effective solvent system for a variety of celluloses, including the high molecular weight cellulose of cotton, when a swelling pretreatment in sodium hydroxide is incorporated. DMI/0.5% LiCl is suitable for use as a mobile phase in gel permeation chromatography to determine the molecular weight of cellulose. The results of using the DMI/LiCl solvent system to determine molecular weight parameters (number-average, weight-average, and peak mo lecular weight) of a variety of celluloses (cotton, rayon, tencel, linen, ramie, flax, kenaf) are reported.

Coordination polymerization in water affording amorphous polyethylenes.

The coordination polymerization of ethylene in water as a reaction medium was studied. Rubbery amorphous branched polyethylene was obtained when a known cationic diimine-substituted methyl complex was employed as a catalyst precursor. High rates of up to 900 TOh(-1) (turnover frequency) were observed. In contrast to solution polymerization in an organic solvent, the rate of suspension polymerization in water increases greatly with ethylene pressure in the range up to 20 bar; this indicates control of the polymerization rate by the concentration of the olefin monomer at the catalytically active site. The effect and mode of mass transfer phenomena were studied. A high catalyst stability in the aqueous coordination polymerization was observed. It was found to be due to an "encapsulation" of the water-insoluble catalyst precursor in the hydrophobic amorphous polymer during the polymerization reaction, and this resulted in strongly restricted accessibility for the aqueous phase. Surprisingly, exposure of the water-stable catalyst precursor to ethylene monomer in solution in the presence of water resulted in immediate decomposition. Polymer microstructure, and thermal and mechanical properties were investigated. The different degree of branching, molecular weight, and corresponding macroscopic properties of the polymers obtained in water as a reaction medium versus solution polymerization in methylene chloride under the same conditions are due to the different phase behavior during polymerization (suspension vs. solution), as opposed to an effect of water on the catalytically active centers.

Competitive Sorption between 1,3-Dichlorobenzene or 2,4-Dichlorophenol and Natural Aromatic Acids in Soil Organic Matter

Previously, we showed that sorption of anthropogenic organic compounds in soils is competitive as a result of the heterogeneous sorption potential of soil organic matter (SOM). We hypothesize that naturally occurring, low mo lecular weight organic molecules or ions could compete with anthropogenic molecules for sorption sites in SOM. We show here that natural aromatic acids suppress sorption from water of 1,3-dichlorobenzene (1,3-DCB) or 2,4-dichlorophenol (2,4-DCP) by up to ∼40% to two soils, a Pahokee peat (93% SOM) and a Cheshire fine sandy loam (3% SOM). The experiments were performed at the natural pH of the soil suspension (5.0 and 5.6, respectively), at which the aromatic acids were mostly ionized. In a screen test at 100 μg/mL aromatic acid concentration, 10 out of 11 competed significantly with 2,4-DCP. Five were selected for further study: vanillic, p-hydroxybenzoic, trans-cinnamic, p-coumaric, and ferulic acids. The selected five aromatic acids as well as the two anthropogenic compounds gave n...

Class-Selective Extraction of Polar, Moderately Polar, and Nonpolar Organics from Hydrocarbon Wastes Using Subcritical Water

The polarity of water drops dramatically when heated under enough pressure to maintain the liquid state. For example, the dielectric constant (e) of water is 80 at ambient temperature, but drops to ∼30 at 250 °C. Thus, low tem perature water can be used to extract polar organics, while higher temperature water will extract moderately polar and nonpolar organics. Four samples (a soil, a catalyst, and two sludges) were extracted by subcritical water at dif ferent temperatures and pressures. At lower temperatures (50−150 °C), phenols and BTEX (benzene, toluene, ethylbenzene, and xylenes) were quantitatively extracted by liquid water, while PAHs (polycyclic aromatic hydrocarbons) and alkanes were not extracted. At 250 or 300 °C, liquid water effectively extracted PAHs, but the high mo lecular weight alkanes (e.g., >C20) were still not extracted. The quantitative extraction of the high molecular weight alkanes was achieved only by super-heated steam (250 and 300 °C at 5 atm) extractions. Class-selective extrac...

Investigation of macromolecules exhibiting the structure of a once-broken rod by molecular optics. 1. Synthesis and investigation of poly(γ-benzyl L-glutamate) with short joints

Samples of poly(ybenzy1 L-glutamate) (PBG) have been synthesized. Their chain contains one of the following fragments. a bis(o-(glycy1amino)phenyl) disulfide, an azobisisobutyrohydrazide, or a decamethylenediamine fragment. These macromolecules were considered to have the shape of a once-broken rod. Solutions of the synthesized samples were investigated in dimethylformamide (DMF) at 25 C by light scattering, flow birefringence (FB), and viscometry. For comparison, similar investigations were carried out for PBG over a wide molecular weight range. Equations were obtained relating intrinsic viscosity to mo- lecular weight for all the investigated structures. The mean-square size of the macromolecules, the second virial coefficients, and the shear optical coefficients were determined. The value of the effective persistence length a was determined for all structures from the experimental data on intrinsic viscosity and FB. It was shown that only the introduction of the decamethylene fragment into the PBG chain decreases the equi- librium rigidity (by 25-30%).

Recent advances in the human physiology of inhibin secretion

The past three years have seen considerable pro­ gress in the field of inhibin physiology and also the emergence of more complex issues. This review provides the background to enable the clinician to appreciate the advances of the field, the emerging problems and the likely relevance of this protein to clinical medicine. Several extensive reviews have been published recently which provide more detail concerning the basic developments in the field (1­ 4). (i) Structure of inhibin and related proteins Although the term "inhibin" was proposed in 1932 (5) to describe a water soluble substance that in­ hibited the development of castration cells within the pituitary gland, the name later became equated with the substance responsible for specific feedback control of FSH secretion. In 1985, inhibin was iso­ lated and shown to be a glycoprotein consisting of two dissimilar subunits, termed a and B, joined by disulphide bonds and which exist in two molecular weight forms of 58 kDa and 32 kDa (6, 7). Subse­ quent cloning of the genes (8, 9) that independently code for the a and B subunits demonstrated that the 32 kDa form was a truncated product of the 58 kDa variety due to cleavage of an NH2-terminal segment of the a subunit. In addition to these mo­ lecular weight forms of what is now termed inhibin [A (aB A ) ] , Ling and colleagues (10) isolated another type of inhibin termed inhibin B which consisted of the identical a subunit joined to a protein which is homologous but structurally distinct from the Bsub­ unit termed BA. Both inhibin A and B appear to be equipotent in their inhibition of FSH secretion in vitro. More recently, dimers of the Bsubunit termed Activin A (BAB A) and Activin AB (BAB s ) have been isolated

Copolymerization of vinyl acetate with acrylonitrile

The copolymerization of vinyl acetate (VAc) with acrylonitrile (AN) in presence of different concentrations of ZnCl2 was investigated in bulk at 65 °C using azobisisobutyronitrile as an ini- tiator. The study was performed by measuring the kinetics of the copolymerization reaction, the molecular weights and the structure of the obtained copolymers and by determining the co¬polymerization parameters. It was observed that the overall copolymerization rates and the mo¬lecular weights of the resultant copolymers increase with increasing the concentration of ZnCl2 in the reaction medium. The rate of the reaction and the molecular weights were observed to be higher in the case of the system containing VAc and AN of 10 to 90 molar ratio with compared to that of the system of 40 to 60 molar ratio. IR spectra of VAc and AN in presence of ZnCl2 sho- wed that the only shift in the absorption bands was observed for the nitrile group of acrylonitrile monomer from 2270 cm-1 to 2260 cm"1. This suggests that, ZnCl2 raises the polarity of the mo- nomer and hence affects the rates of ali the elementary polymerization reactions.

Characterization of lipoprotein in a kindred with familial hypercholesterolemia

To study possible consequences of decreased num- bers of cellular LDL receptors on plasma lipoproteins, we characterized the low density and high density lipoproteins in fasting plasmas of a kindred with receptor-defective hyper- cholesterolemia. The flotation rates ($1,,)63) of the major LDL populations, determined by analytic ultracentrifugation, ranged from 4.7 to 7.4; densities (dZ0) ranged from 1.0348 to 1.0402 g/ml, and minimum molecular weights ranged from 2.5 to 3.5 X 10. On rate zonal ultracentrifugation, the major pop- ulations of LDL isolated from individual members of this kindred could be divided into fast and slow floating varieties. Fast floating LDL had a molecular weight >3.15 X lo, slow floating, <2.85 X 10. Both fast and slow floating LDL were found among affected members of the kindred. From molec- ular weights and chemical compositions, the numbers of mol- ecules of lipid components per LDL particle were calculated. Numbers of phospholipid, free cholesterol, and cholesteryl ester molecules were each strongly correlated with the mo- lecular weights of the LDL particles. Thus, the differences in mass of LDL resulted from alterations primarily of the phos- pholipid, free cholesterol, and cholesteryl ester contents per particle, whereas the amounts of protein and triglyceride per particle were relatively constant. An important and consistent finding of this study is that the LDL of members of the kindred affected with familial hypercholesterolemia (FH) differed from LDL of unaffected members by containing more molecules of cholesteryl ester and less triglyceride, even when LDL were matched for molecular weight. Thus, FH per se affected the core lipid composition of LDL. The mechanisms responsible for the change are unknown. Analysis of the distribution of LDL masses in this pedigree is compatible with genetic factors having some influence on LDL mass, but the great overlap of LDL mass between affected and nonaffected subjects implies that, whatever genetic or other factors limit LDL mass, these factors remain operative in FH. Hepatic apoB (B-100, B- 74, and B-26) comprised 96% of the protein moiety in all subjects, while intestinal apoB (B-48) was not found in any of the LDL preparations. Therefore, LDL of both normal and affected members probably is derived from hepatic lipopro- teins. HDL-cholesterol was low in children with FH, but it was also low in an unaffected child and there was no correlation between the presence or absence of HDLz and FH status. There appeared to be a tendency toward lower LDL-choles- terol in those affected subjects whose plasma contained HDL2. However, this suggestive inverse relationship between LDL and HDL2 needs confirmation.-Patsch, W., R. Ostlund, I. Kuisk, R. Levy, and G. Schonfeld. Characterization of lipo- protein in a kindred with familial hypercholesterolemia. J. Lipid RFS. 1982. 23: 1196-1205.

THE EVOLUTION OF SPIDER WEBS

vancement of Science that John Henry Comstock of Cornell University presented a paper on the evolution of the webs of spiders. With the advance since then in our knowledge of spiders, particularly with respect to the habits of certain species in the Palearctic, Ethiopian, and Australian Realms, my task is made immeasurably less difficult than it was for this pioneer among American araneologists. In older classification schemes, the cate? gories Retitelariae and Vagabondes gave an indication (as can be deduced from the latter name) that not all spiders build snares. However, although they do not all make webs, they all produce silk, the very name (Spinne in German and Spindlar in Swedish) alluding to the spinning activity. What is this material they spin, and how is it manipulated? It has been found that silk, made of a scleroprotein, fibroin, while yet within the silk glands in liquid form, has a molecular weight of 30,000 (Braunitzer and Wolff, 1955). After emission the fibroin has a mo? lecular weight of about 200,000 to 300,000. We can assume that polymerization occurs, forming additional peptide linkages. The four amino acids glycine, alanine, serine, and tyrosine compose over 90% of the molecule. Apparently the coagulation and hardening occur not as a result of enzyme action, but rather as a result of the me? chanical stretch exercised upon the mate? rial as the spider draws the line out of the spinnerets (DeWilde, 1943). Spiders pro? duce silk from several different glands, the physical properties varying in accordance with this, as well as from species to species. As to thickness of fiber, Hopfmann (1935) gives a range of from 12 to 0.5 /*, Witt

Value of Hot Oil as a Means of Disinfecting Instruments

La h e y and Mason,1 Loretz,2 Foster, LeMay and Johnstone,8 Parke4 and Harvey, LeMay and Shuttleworth,5 stated that hot oil is superior to other means of disinfecting dental handpieces and delicate metallic instruments, in that it prolongs the efficiency of the instru­ ments. Differences of opinion exist regarding the time required and the temperature at which oil should be maintained for disinfection and sterilization of instru­ ments. Appleton6’7 concluded that ordi­ nary mineral or paraffin oil at 130 C. for five minutes will suffice if only asporogenic bacteria-are considered; but if one wishes to destroy bacterial spores, 185 C. for five minutes, 175 C. for 10 minutes or 165 G. for 15 minutes should be used. Foster, LeMay and Johnstone3 empha­ sized the need for at least 30 minutes at 150 G. for sporicidal effect. Loretz2 has suggested a germicidal oil which is reported to be effective within 15 min­ utes at 100 C. in sterilizing handpieces contaminated with a spore-forming bac­ terium, which resisted oil at 100 G. for 15 minutes. Harvey, LeMay and Shuttleworth5 used two mixtures: (1) AC. 10 (surgi­ cal), consisting of 95 per cent of a light petroleum neutral oil (containing ap­ proximately 64 per cent paraffins, 31 per cent naphthenes, 5 per cent aromatics) and 5 per cent of a complex of metallic petroleum sulphonates of mo­ lecular weights between 400 and 500 and average composition of the order C24H37SO3X-C30H50SO3X, and (2) AG. 10 soda solution, a mixture of 2 Gm. of sodium carbonate decahydrate and 2 cc. of AC. 10 (surgical) in enough water to make 100 cc. The suggested technic was to soak the handpieces in AC. 10 (surgical), boil and allow to dry over­ night, and after each use boil in AC. 10 soda solution. Five minutes’ boiling in AC. 10 soda solution was considered ef­ fective in destroying vegetable cells, but more than 30 minutes was necessary to be absolutely certain of complete de­ struction of spores. In reference to the time required to kill spores, Harvey, Le­ May and Shuttleworth5 state: