Zinc chloride

Here, we test the new methods described above on a wide range of real SAD, MAD and SIRAS merged diffraction data sets. For our tests, only the intensities or structure-factor amplitudes, along with the sequence for a protein monomer, the number of substructure atoms expected per monomer and the f′ and f′′ values for the substructure atoms were input. CRANK used AFRO and CRUNCH2 for substructure detection, BP3 for substructure phasing and SOLOMON with MULTICOMB for density modification. Three cycles of Buccaneer iterated with REFMAC were used for automated model building with iterative refinement. The default options or parameters were used in all programs. The defaults set by CRANK depend upon the particular experiment: for SAD data, AFRO uses the multivariate |F_A| value calculation and MULTICOMB uses the multivariate SAD function for phase combination in density modification, while Buccaneer uses the SAD function implemented in REFMAC. For SIRAS data, AFRO calculates |F_A| from either the anomalous signal or using isomorphous differences by determining which signal is greater. BP3 uses the uncorrelated SIRAS function described previously (Pannu et al., 2003 ▶ ) and SOLOMON uses MLHL phase combination in MULTICOMB, while Buccaneer uses the multivariate SIRAS function in REFMAC. Finally, for MAD data AFRO chooses the wavelength with the greatest anomalous signal and calculates multivariate F_A values from it. Similar to SIRAS data, SOLOMON uses MLHL phase combination in MULTICOMB to perform density modification and Buccaneer uses the MLHL likelihood function in REFMAC for model refinement.
In the test cases below, the previous version of CRANK, version 1.3, is tested with the current version, version 1.4. The main differences between the two versions are the development version of AFRO that calculates multivariate |F_A| values given SAD data and the use of MULTICOMB for phase combination in density modification, which were both introduced in version 1.4.
In total, we report results from 116 real data sets from several different sources listed in Appendix A. The data sets cover a wide range of resolutions (from 0.94 to 3.29 Å) and anomalous scatterers, including selenium, sulfur, chloride, sulfate, manganese, bromide, calcium and zinc. Of the 116 data sets, 63 are MAD data sets, 46 are SAD data sets and seven are SIRAS data sets.

Plant collection and identification. Fresh pods of A. nilotica were collected in June 2008 from Potiskum, Yobe State, Nigeria. The pods were identified by a taxonomist in Department of Biological Sciences, University of Maiduguri, Maiduguri, Nigeria. The pods were air dried for three weeks under the shade and ground into fine powder.
Preparation of aqueous extract. Three hundred and fifty grams (350 g) of the powdered extract sample were exhaustively extracted with distilled water using reflux method. The crude aqueous extract was concentrated in vacuo and a brown colored extract weighing two hundred and sixty three grams (263 g) w/w was obtained. It was thereafter stored in a refrigerator at 4 ˚C until used.⁴ Fractionation of the aqueous pod extract. The method used for fractionation of A. nilotica pod powder has already been reported.^{5 (link),6} The crude aqueous pod extract was suspended in cold distilled water and then filtered using Whatman filter paper. The filtrate was thereafter subjected to fractionation using, chloroform, ethyl acetate and n-butanol. The fractionation with the organic solvents of different polarity was done until the organic layers were visibly clear to obtain ethyl acetate (58 g), n-butanol (25 g) soluble fractions and the residue (180 g). The product did not dissolve in chloroform, hence no product was obtained as shown in Fig. 1.
Phytochemicalanalysis of theextracts of A.nilotica. The aqueous extract and ethyl acetate, N-butanol and residual fractions of A. nilotica extracts were subjected to qualitative chemical screening for identification of various classes of active chemical constituents.^{7 , 9} Test for tannins (Ferric chloride test). Two millilitres (2 mL) of the aqueous solution of the extract were added to a few drops of 10% Ferric chloride solution (light yellow). The occurrence of blackish blue colour showed the presence of gallic tannins and a green-blackish colour indicated presence of catechol tannins.
Test for saponins (Frothing Test). Three millilitres (3 mL) of the aqueous solution of the extract were mixed with 10 mL of distilled water in a test-tube. The test-tube was stoppered and shaken vigorously for about 5 min, it was allowed to stand for 30 min and observed for honeycomb froth, which was indicative of the presence of saponins.
Test for alkaloids. One gram (1 g) of the extract was dissolved in 5 mL of 10% ammonia solution and extracted with 15 mL of chloroform. The chloroform portion was evaporated to dryness and the resultant residue dissolved in 15 mL of dilute sulphuric acid. One quarter of the solution was used for the general alkaloid test while the remaining solution was used for specific tests.
Mayer’s reagent (Bertrand’s reagent). Drops of Mayer’s reagent was added to a portion of the acidic solution in a test tube and observed for an opalescence or yellowish precipitate indicative of the presence of alkaloids.
Dragendorff’s reagent. Two millilitres (2 mL) of acidic solution in the second test-tube were neutralized with 10% ammonia solution. Dragendorff’s reagent was added and turbidity or precipitate was observed as indicative of presence of alkaloids.
Tests for carbohydrate (Molisch’s test). A few drops of Molischs solution was added to 2 mL of aqueous solution of the extract, thereafter a small volume of concentrated sulphuric acid was allowed to run down the side of the test tube to form a layer without shaking. The interface was observed for a purple colour as indicative of positive for carbohydrates.
Testsforcarbohydrate (Barfoed’stest). One milliliter (1 mL) of aqueous solution of the extract and 1ml of Barfoed’s reagent were added into a test-tube, heated in a water bath for about 2 min. Red precipitate showed the presence of monosaccharaides.
Standard test for combined reducing sugars. One milliliter (1 mL) of the aqueous solution of the extract was hydrolyzed by boiling with 5 mL of dilute hydrochloric acid (HCl). This was neutralized with sodium hydroxide solution. The Fehling’s test was repeated as indicated above and the tube was observed for brick-red precipitate that indicated the presence of combine reducing sugars.
StandardtestforfreereducingSugar (Fehling’stest). Two milliliters (2 mL) of the aqueous solution of the extract in a test tube was added into 5 mL mixture of equal volumes of Fehling’s solutions I and II and boiled in a water bath for about 2 min. The brick-red precipitate was indicative of the presence of reducing sugars.
Test for ketones. Two millilitres (2 mL) of aqueous solution of the extract were added to a few crystals of resorcinol and an equal volume of concentrated HCl, and then heated over a spirit lamp flame and observed for a rose colouration that showed the presence of ketones.
Testforpentoses. Two millilitres (2 mL) of the aqueous solution of the extract were added into an equal volume of concentrated HCl containing little phloroglucinol. This is heated over a spirit lamp flame and observed for red colouration as indicative of the presence of pentoses.
Test for phlobatannins (HCl test). Two millilitres (2 mL) of the aqueous solution of the extract were added into dilute HCl and observed for red precipitate that was indicative the presence of phlobatannins.
Test for cardiac glycosides. Two millilitres (2 mL) of the aqueous solution of the extract was added into 3 drops of strong solution of lead acetate. This was mixed thoroughly and filtered. The filtrate was shaken with 5 mL of chloroform in a separating funnel. The chloroform layer was evaporated to dryness in a small evaporating dish. The residue was dissolved in a glacial acetic acid containing a trace of ferric chloride; this was transferred to the surface of 2 mL concentrated sulphuric acid in a test tube. The upper layer and interface of the two layers were observed for bluish-green and reddish-brown colouration respectively as indicative of the presence of cardiac glycosides.
Test for steroids (Liebermann-Burchard’s test). The amount of 0.5 g of the extract was dissolved in 10 mL anhydrous chloroform and filtered. The solution was divided into two equal portions for the following tests. The first portion of the solution above was mixed with one ml of acetic anhydride followed by the addition of 1 mL of concentrated sulphuric acid down the side of the test tube to form a layer underneath. The test tube was observed for green colouration as indicative of steroids.
Test for steroids (Salkowski’s test). The second portion of solution above was mixed with concentrated sulphuric acid carefully so that the acid formed a lower layer and the interface was observed for a reddish-brown colour indicative of steroid ring.
Test for flavonoids (Shibita’s reaction test). One gram (1 g) of the water extract was dissolved in methanol (50%, 1-2 mL) by heating, then metal magnesium and 5 - 6 drops of concentrated HCl were added. The solution when red was indicative of flavonols and orange for flavones.
Testforflavonoids (pew’stest). Five millilitres (5 mL) of the aqueous solution of the water extract was mixed with 0.1 g of metallic zinc and 8ml of concentrated sulphuric acid. The mixture was observed for red colour as indicative of flavonols.
Test for anthraquinones (Borntrager’s reaction for free anthraquinones). One gram (1 g) of the powdered seed was placed in a dry test tube and 20 mL of chloroform was added. This was heated in steam bath for 5 min. The extract was filtered while hot and allowed to cool. To the filtrate was added with an equal volume of 10% ammonia solution. This was shaken and the upper aqueous layer was observed for bright pink colouration as indicative of the presence of Anthraquinones. Control test were done by adding 10 mL of 10 % ammonia solution in 5ml chloroform in a test tube.
Elemental analysis. The elemental content was determined using the standard calibration curve method.^{10 (link),11 (link)} Zero point (0.5 g) of air dried sample in an evaporating dish was placed in an oven at 80 ˚C and dried to a constant weight. The sample was placed in a weighing crucible and ashed at 500 ˚C in a hot spot furnance for three hours. The ashed material was prepared for the determination of trace element. A portion of zero point (0.5 g) of the ashed sample was digested by heating for two min with a mixture of 10 mL each of nitric acid (HNO₃), HCl and a perechloric acid in a 500 mL flask. The aliquot obtained from this mixture by filtration was mixed with a 10 mL of 2M HNO₃ and 30 mL of distilled water in a 100 mL volumetric flask. The volume was made up to zero mark with distilled water. Blank sample and standard solution for the various elements were similarly done. All samples placed in a plastic container and stored in a refrigerator maintained at 4 ˚C prior to analysis. Flame emission spectrometer (Model FGA-330L; Gallenkamp, Weiss, UK) was used to determine sodium (Na) and potassium (K) concentrations. Other elements, magnesium (Mg), calcium (Ca), iron (Fe), lead (Pb), zinc (Zn), manganese (Mn), cadmium (Cd), copper (Cu) and arsenic (As) were determined by atomic absorption spectrometry with (Model SPG No. 1; Unicam, Cambridge, UK) at the appropriate wave-length, temperature and lamp current for each element.¹²

The experimental material was rubidium chloride (RbCl, 99% wt%) provided by a company in China. It was produced by the solvent extraction method, in which the extraction and reverse extraction reagents were phenolic reagents and hydrochloric acid, respectively. In the extraction process, silicon (Ⅳ) and zinc (Ⅱ) in the solution are easily extracted into the organic phase by phenolic reagents, and the organic phase is extracted by hydrochloric acid to obtain silicon tetrachloride and zinc chloride [17 (link),18 (link)]. At the same time, RbCl will also form a double salt Rb₂SiCl₆ with SiCl₄, so the resulting rubidium chloride is easily mixed with SiCl₄, Rb₂SiCl₆ and ZnCl₂ [19 (link),20 (link)].
Before the experiment, considering that rubidium chloride is hygroscopic and easily absorbs moisture in the air, and that SiCl₄ is a liquid at room temperature and has a low boiling point of 330 K, we first carried out drying pretreatment of raw materials, dried at 353 K for 8 h, and removed residual moisture and possible SiCl₄. The physical phase of the raw material is shown in Figure 1, which only contains rubidium chloride, and the content of other elements is low, which is not detected. The morphology and element distribution of the raw material are shown in Figure 2. Rubidium chloride has an irregular shape and uneven particle size. The distribution of the element chlorine coincides with the distribution of rubidium, silicon and zinc and is evenly distributed. After drying at 353 K for 8 h to remove residual water and possible silicon tetrachloride, the remaining silicon exists in the form of the double salt Rb₂SiCl₆. After drying, the content of impurity elements silicon and zinc in rubidium chloride is 1206 mg/kg and 310 mg/kg, respectively.

Magnesium oxide catalyst in varying concentrations was used to study the effects of catalyst type and quantity (50 mg and 75 mg). In addition, different types of catalysts, including magnesium oxide, stannous chloride dihydrate, calcium oxide, aluminum oxide, ferric oxide, zinc chloride, zinc metal, zinc oxide, calcium chloride, antimony trioxide, Arsen III oxide, titanium oxide, strontium chloride, and magnesium metal, were used to investigate the type of catalyst used in the polymerization of PLLA.

A generous donation of isosorbide dinitrate (ISDN, USP, 40 mg) was provided by the EIPICO Company in Cairo, Egypt, bioavailability of ISDN is approximately 25%. P-Toluene Sulphonic Acid, Maleic anhydride, Zinc chloride, Calcium chloride, zinc oxide, xylene and diethyl ether from Alpha Chemika (India) and magnesium oxide from BDH laboratory supplies in Poole, BH151TD (England). From BIO CHEM (Egypt), Polyvinyl alcohol (M.wt 10.000), decalin and chloroform (assay 99%), pure ethyl alcohol (assay 99.9%), Ferric oxide, Magnesium chloride, Arsen (III) oxide, Acetone, Magnesium metal, Phthalic anhydride, Tin oxide, Antimony oxide, potassium hydroxide, phenphethalin, and stannous chloride dihydrate. Calcium oxide and l(+) lactic acid (assay 88–92%) were obtained from LOBA CHEMIE (India). Aluminum oxide was purchased from RIEDEL–DE HAEN AG SEELZE-HANNOVER (China). Zinc metal, tween 80, anhydrous hydrogen phosphate, Potassium dihydrogen orthophosphate, and Sodium chloride were purchased from ADWIC (Egypt). Pluronic F88 and Tetronic 1307 were gifted from BASF, USA. Without additional purification, all substances were utilized precisely as they were given.