Mixture Of Talc Research Articles

Development of rabbit embryos to the hatched blastocyst stage in rabbit peritoneal fluid [formula omitted

The talc-Celite technique has now been adapted for the recovery of enteroviruses from potable waters. Layers containing a 3:1 mixture of talc and Celite 503 were sandwiched between two sheets of Whatman 114 filter paper with an AP 25 (Millipore) prefilter disc on top. For the processing of 1-1 volumes, layers (300 mg talc and 100 mg Celite) were held in a 47 mm diameter filter holder. Layers containing 1.2 g talc and 0.4 g Celite were prepared in 142 mm diameter metallic (Sartorius) holders for experiments with larger (10 to 1000 l) sample volumes. Before experimental contamination and passage through the layer, conditioning of dechlorinated water was carried out by adjusting its pH to 6.0 and the addition of Earle's balanced salt solution (EBSS) to a final concentration of 1:100. For 1-1 volumes, layer-adsorbed virus was elutedin situ with 10–20 ml of 10% fetal calf serum in normal saline (pH 9.0). Because 100 ml amounts of the same eluent were required when working with the larger layers, a 10-fold reduction in the volume of the eluate was achieved by placing it in a dialysis sac and subjecting it to overnight (4°C) hydroextraction with polyethylene glycol 6000.When working with poliovirus (type 1, Sabin)-contaminated sample volumes of 1- to 20-1, between 83–95% of the input virus could be recovered with this technique. In experiments with 100 to 1000 litre amounts, containing as little as 1.2 plaque forming units (PFU) of poliovirus 1−1, between 58–64% of the added virus could be recovered with a sample concentration of up to 100,000-fold. In 1- to 20-1 volume experiments with echovirus 6 and coxsackieviruses A9 and B5, 81–92% of the input PFU could be recovered.

POLLEN INTERFERENCE AND CRYPTIC SELF‐FERTILITY IN CAMPSIS RADICANS

The effect of self pollen on the success of cross pollinations was studied in Campsis radicans (L.) Seem., a species previously considered self‐sterile. The application of self pollen to stigmas in combination with or preceding the application of cross pollen markedly reduced the likelihood of fruit production. This effect was not due to the dilution of cross pollen nor to physical blocking of the stigmatic surface, since mixtures of talc and cross pollen were as effective as pure cross pollen in causing fruit production. Pollen tubes produced by self pollen grew at rates similar to those from cross pollen, and penetrated the ovary. The interference caused by self pollen appears to take place in the ovary, although it cannot be stated to what degree it is prezygotic or postzygotic. The marked protandry occurring in C. radicans is presumed to be due at least partly to selection for avoidance of these negative effects on female reproductive success. Up to 33% of viable seeds from mixed self + cross pollinations were sired by self pollen. The term “cryptic self‐fertility” is coined to describe this phenomenon where pollination with loads of pure self pollen rarely or never yields fruit, but pollination using mixtures of self and cross pollen yields fruit containing considerable numbers of selfed seed. Estimates of selfing frequency that are based on pollination using loads of purely self pollen will be in error for species possessing cryptic self‐fertility.

Influence of auxins, thiamine and fungal drenches on the rooting ofProsopis albaclone B2V50cuttings

SummaryGrowth regulator and fungicide concentrations were identified for rooting cuttings of high-biomass-producing Prosopis alba clones. IBA and NAA concentrations of 0.0%, 0.3%, 1.2% and 3.6% (w/w) in talc were compared for their ability to stimulate rooting under recently identified optimum environmental conditions. IBA stimulated greater rooting percentages than NAA, and 1.2% IBA had the greatest rooting percentage (59%) and number of roots per cutting. A 1.2% IBA in talc mixture was not significantly different from a previously described and more complicated DMSO-based mixture. Fungal drenches of captan, benomyl and banrot were compared with a control. The greatest percentage rooting occurred with the low concentration of banrot (0.5 g l−1) and the control. Benomyl and banrot strongly inhibited the rooting percentage at the highest concentration (1.0 g l−1) examined.

Synthesis of cordierite from natural materials in the presence of Al2O3-containing components

We have examined some well known reactions of the synthesis of cordierite from natural materials and alumina. The volume changes occurring during these reactions, the yield of cordierite, and the value of the Gibbs free energy have been calculated. It is established that the most favorable method under industrial conditions is to synthesize cordierite from a stoichiomeric mixture of talc, kaolin and alumina. The phase composition of the cordierite sinters based on these materials has been studied. The synthesis of cordierite can be done in the presence of Al2O3-containing components on condition that the firing temperature does not exceed 1659°K when the sintering of the materials is effected in parallel. X-ray and IR-spectrometric studies were carried out on the chamotte and corundum-corderite materials confirming the coexistence of corundum and cordierite as two noninteracting phases at T≤1659°K.

Solid-state reactions in the system talc-CaCo 3 doped with Co(II) at high temperatures

Four solid reaction mixtures of talc- x CaCO 3-0.2 CoCl 2·6 H 2O in the molar ratio 1 : x:0.2 ( x = 1, 2, 3 and 4) were prepared and thermally treated at 1000 and 1200°C. The resulting coloured reaction products were identified—after sudden cooling to room temperature—by means of X-ray diffraction and ligand-field absorption spectrum methods. Analysis of the reaction products obtained at 1000°C showed diffracted lines as well as absorption bands characteristic of phases (I) Co-diopside Ca(Mg, Co)Si 2O 6 at x = 1, (II) Co-diopside, Co-monticellite Ca(Mg, Co)SiO 4 and Co-akermanite Ca 2(Mg, Co)Si 2O 7 varying in concentrations at x = 2 and 3, and (III) Co-akermanite and Co-monticellite at x = 4. On the other hand, analysis of the reaction products treated further at 1200°C confirmed the presence of the same phases formed in the reaction mixtures at x = 1 and 4, whereas Co-monticellite seemed to dissociate where x = 2 and 3. However, the intensities of both diffracted lines and absorption bands of the corresponding phases were found to increase on increasing the firing temperature and CaCO 3 concentration. Generally, the results are discussed in view of formation enthalpies as well as spectra of differently coordinated Co(II) in silicate structures.

Weathering of Enstatite to Talc Through a Sequence of Transitional Phases

AbstractOrthopyroxene (En85) weathers initially by vacancy diffusion, and through this process hydration occurs and a sequence of biopyriboles develops, culminating in a talc-like layer silicate whose structure joins coherently to the orthopyroxene structure. Oxidation of Fe2+ to Fe3+ colors the altering pyroxene yellow. The ‘talc’ does not remain in structural coherence with the pyroxene after it has exceeded a few tens of nanometers in size; it is replaced by a mixture of talc and smectite. In some areas the mixture has an epitactic relation to the pyroxene, but commonly it fills faceted solution holes without crystallographic relation to the parent structure. Continued weathering extends the yellow zone at the periphery of the orthopyroxene, and the alteration product increases in smectite and decreases in 'talc’ During this stage of the reaction, MgO and SiO2 are released to form colorless true talc around the altering pyroxene. Eventually, the yellow alteration may become a smectite pseudomorph after orthopyroxene or it may be changed entirely to a mixture of vein talc and iron oxides. The complete conversion of orthopyroxene to talc plus oxides thus takes place through three sequential mineral reactions without the development of a noncrystalline phase.

Concentration of seeded simian rotavirus SA-11 from potable waters by using talc-celite layers and hydroextraction.

There is mounting evidence for the waterborne transmission of diarrhea caused by rotaviruses. As a result, proper techniques are required for their recovery from samples of incriminated water. The combined efficiency of the talc-Celite technique and polyethylene glycol 6000 hydroextraction was, therefore, tested for this purpose, using Simian rotavirus SA-11 and MA-104 cells. Conditioning of the dechlorinated tap water samples was carried out by pH adjustment to 6.0 and the addition of Earle balanced salt solution to a final concentration of 1:100. Passage of a 1-liter volume of such a conditioned sample through a layer containing a mixture of talc (300 mg) and Celite 503 (100 mg) led to the adsorption of nearly 93% of the added SA-11 plaque-forming units. For the recovery of the layer-adsorbed virus, 3% beef extract and 1x tryptose phosphate broth were found to be superior to a variety of other eluents tested. When we tested 100-liter sample volumes, layers containing 1.2 g of talc and 0.4 g of Celite were employed. Virus elution was carried out with 100 ml of tryptose phosphate broth. The eluate was concentrated 10-fold by overnight (4 degrees C) hydroextraction with polyethylene glycol. With a total input virus of 7.0 x 10(5) and 1.4 x 10(2) plaque-forming units, the recoveries were about 71 and 59%, respectively.

Discrimination of colours and grey shades by Merino ewes: Tests using coloured lambs

The tendency of lactating ewes to run to lambs visible some distance away, was used to examine the responsiveness of ewes to various colours and to test the ewes for colour vision. Lambs were coloured red, orange, yellow, green or blue (colour series) and white, black or one of eight shades of grey (grey series) by dusting pigments or mixtures of talc and carbon black into the coat. Ewes presented with their own lamb immediately after colouring showed various types of abnormal behaviour, the incidence of which clearly increased with increased darkness of grey. In the colour series there were few abnormal responses to yellow, more to orange and a high incidence with green, blue and red. Thus red is either seen as a dark colour or has a special visual impact. Tests on colour vision were carried out 3–4 days later when ewes had become accustomed to the colour of their lambs. In these tests, ewes and lambs were separated for several hours, and “multiple choice” tests were then conducted using 4 or 5 alien lambs each in a separate wire-mesh cage; one of the lambs was the same colour as the ewe's own lamb while the others were from the grey series. The ewe was released 7 m from the cages, and her choice of cage was assessed by several criteria. Two consecutive tests were done so that each ewe was offered a choice between own colour and most of the grey shades. The ewes showed a significant preference for own colour when this was red, orange, yellow and white, but ewes whose lambs were blue, green, a light grey, a darker grey or black performed poorly. These results indicate that ewes have some sort of spectral vision, at least for colours in the longer wavelength range.

Use of talc-celite layers in the concentration of enteroviruses from large volumes of potable waters

The talc-Celite technique has now been adapted for the recovery of enteroviruses from potable waters. Layers containing a 3:1 mixture of talc and Celite 503 were sandwiched between two sheets of Whatman 114 filter paper with an AP 25 (Millipore) prefilter disc on top. For the processing of 1-1 volumes, layers (300 mg talc and 100 mg Celite) were held in a 47 mm diameter filter holder. Layers containing 1.2 g talc and 0.4 g Celite were prepared in 142 mm diameter metallic (Sartorius) holders for experiments with larger (10 to 1000 l) sample volumes. Before experimental contamination and passage through the layer, conditioning of dechlorinated water was carried out by adjusting its pH to 6.0 and the addition of Earle's balanced salt solution (EBSS) to a final concentration of 1:100. For 1-1 volumes, layer-adsorbed virus was eluted in situ with 10–20 ml of 10% fetal calf serum in normal saline (pH 9.0). Because 100 ml amounts of the same eluent were required when working with the larger layers, a 10-fold reduction in the volume of the eluate was achieved by placing it in a dialysis sac and subjecting it to overnight (4°C) hydroextraction with polyethylene glycol 6000. When working with poliovirus (type 1, Sabin)-contaminated sample volumes of 1- to 20-1, between 83–95% of the input virus could be recovered with this technique. In experiments with 100 to 1000 litre amounts, containing as little as 1.2 plaque forming units (PFU) of poliovirus 1 −1, between 58–64% of the added virus could be recovered with a sample concentration of up to 100,000-fold. In 1- to 20-1 volume experiments with echovirus 6 and coxsackieviruses A9 and B5, 81–92% of the input PFU could be recovered.

Studies on a Eutectic Glass Composition in the System MgO-Al2O3-SiO2

The composition, MgO 20.3, Al2O3 18.3 and SiO2 61.4 per cent, corresponding to the ternary eutectic at 1345° in the system MgO-Al2O3-SiO2, can be approximately obtained using a mixture of talc and clay. Hot stage microscopic studies revealed that the gross eutectic mixture of talc and clay readily melts to clear glass at a temperature as low as 1375°C. The observation has been discussed in the light of earlier X-ray and DTA studies and it has been concluded that rapid vitrification of the mixture is due to high reactivity of the starting materials.High temperature viscosity, thermal expansion, transverse strength, resistance to water attack, the DC and AC resistivities and dielectric strength of the eutectic glass composition were measured and it has been shown that most of the properties compare favourably with those of the soda-lime-silica and the heat resistant boro-silicate type of glasses.

Reaction and Fired‐Property Studies of Cordierite Compositions

Ceramic bodies approaching the theoretical composition of cordierite were prepared from mixtures of talc and clay; talc, clay, and varying amounts of MgCO3; talc, clay, and alumina; and prochlorite and clay. Additions of BaCO3 and PbSiO, were made. Differential thermal analysis and X‐ray diffraction methods were used in reaction studies of each composition. Bodies had thermal expansions from 0.344 to 0.109% (25° to 900°C.). BaCO3 and PbSiO3 affected thermal expansion. Dielectric properties were improved by additions of BaCO3 and were markedly improved by additions of both BaCO3 and PbSiOl. Cordierite started to crystallize at about 1250°. Additions of PbSiO3 lowered this temperature about 50°C. With sufficient BaCO3, the Ba‐C phase, as described by Wisely, crystallized in place of cordierite. The crystallization temperature for the Ba‐C phase was about 1200°C. With insufficient BaCO3, both cordierite and Ba‐C formed. Additions of PbSiO3 reduced the crystallization temperature of the Ba‐C phase by 50°C. and increased the glassy phase. Several of the compositions should haw considerable practical value.

Studies on Formation and Recrystallization of Intermediate Reaction Products in the System Magnesia‐Silica‐Water

Mixtures of magnesia and silicic acid ranging in composition from 0.5 to 2.0 M/S were treated hydrothermally at temperatures of 75° to 350°C. for various periods of time. The reaction solids were examined by differential thermal analysis, X ray, and electron microscopy and analyzed chemically. The intermediate products of reaction ranging in composition between that of talc (0.75 M/S) and chrysotile (1.5 M/S) comprised a continuous series of cryptocrystalline needle‐like crystaIs matted tightly together and showing the same X‐ray pattern. The initial reaction product of the 0.75 to 1.50 M/S raw mixtures was a cryptocrystalline solid having a 1.5 M/S ratio. This phase subsequently reacted with the residual silica, so long as any was available, to form a solid having the composition of the raw mix, but only at relatively moderate temperatures(100°to175°C.). As the temperature was increased the crystals of the 0.75 and 1.50 M/S compositions increased in size, but all remained submicroscopic. The compositions intermediate between 0.75 and 1.5 M/S crystallized as mixtures of talc and chrysotilelike products. The chrysotilelike product appeared as minute needles which did not possess any apparent flexibility.