Addition Of Iodine Solution Research Articles

ISOLASI DAN SELEKSI KHAMIR AMILOLITIK ASAL BUAH NANGKA (Artocarpus heterophyllus Lam.)

The aim of this research is to find the isolates of yeast that have the ability to produce enzyme amylase. The strains that can produce the amylase enzyme are characterized by a clear zone around colonies after addition of iodine solution in medium containing 1% starch soluble. Activity of amylase enzyme can be determined by measuring using spectrophotometer at λ 540 nm. The isolation result obtained 75 representative yeast isolates with colony color white butyrous 16%, white mucoid 29.3%, yellowish white 18.7%, cream 20%, peach mucoid 9.3%, and orange mucoid 6,7%. Screening results showed that 8 isolates were able to produce an amylase enzyme with code isolates K33, K34, K36, K37, K48, K107, and K128. A total of two potential yeast isolates in yielding amylase with K34 and K39 isolate codes had amylolytic index 2.89 and 2.27. The highest enzyme activity was produced by K48 (0.88 U/mL).

Development of an antibiotic-free plasmid selection system based on thymine auxotrophy in Lactococcus lactis

Lactococcus lactis has become the best studied species of the lactic acid bacteria (LAB) clade and an ideal cell factory for heterogenous proteins. We have constructed an antibiotic-free expression vector, pMG-thyA, using thymidine synthase gene thyA as the selection marker. The thyA gene was cloned from the food industry strain Streptococcus thermophilus St-JY and was used to replace the erythromycin resistance genes on L. lactis expression vector pMG36e in order to construct pMG-thyA. The construction of the new vector and thyA-null host L. lactis MG1363-TT yielded an antibiotic-free expression system. The α-amylase gene (amy) was cloned onto the multiple cloning site of the vector pMG-thyA as a reporter gene, yielding the recombinant plasmid pMGthyA-amy. This plasmid was electroporated into L. lactis MG1363-TT, and the recombinant strain grown on SA plates containing 0.5 % (w/v) soluble starch formed distinct bacterial colonies and clear zones (halo) around the colonies following the addition of iodine solution. These research findings lay the foundation for food-grade expression in L. lactis.

Simple spectrophotometric method for determination of polyvinylalcohol in different types of wastewater

The determination of polyvinylalcohol (PVA) by the formation of the blue iodine–PVA complex method was established for a semi-micro method scale. The direct addition of iodine solution proved to be a better iodine source than iodine generated in situ. The ageing of reagents requires frequent calibrations. Common biopolymers such as starch, albumin and cellulose produced much lower colour intensity with reagents and their impact on the analysis is negligible. The method is not affected by paper filter filtration. The detection of PVA was successfully tested in different wastewater types and the method proved to be a powerful tool for PVA detection. It must be emphasised that quantification of PVA is strongly dependent on the PVA type and the quantification capacity; without information of the PVA structure or type is only tentative.

An ambipolar behavior of novel ethynyl-bridged polythiophenes—A comprehensive study

The article contains a comprehensive study regarding the synthesis and properties of novel polythiophenes, where bithiophene units are linked with either ethynyl or bisethynylarylenyl bridges. A convenient and selective method for lithiation of 2,2′-bithiophene, with the aid of n-butyllithium in dialkyl ether/n-hexane solution under mild conditions (−5 to 5°C), is also presented. The lithiation, followed by the addition of iodine solution at room temperature constituted a robust method towards the synthesis of 5-iodo-2,2′-bithiophene, which was then used as a key substrate in the Sonogashira-type cross-coupling reactions. The coupling of 5-ethynyl-2,2′-bithiophene with 5-iodo-2,2′-bithiophene, mediated by [PdCl2(PPh3)2]/CuI couple, resulted in the formation of 1,2-bis(2,2′-bithiophene-5-yl)ethyne. The synthesized monomers of Bt–A–Bt (where Bt=2,2′-bithiophene-5-yl) type, namely: 1,2-bis(2,2′-bithiophene-5-yl)ethyne, 1,4-bis(2,2′-bithiophene-5-yl)buta-1,3-diyne and 1,4-bis(2,2′-bithiophene-5-ylethynyl)benzene were transformed into conducting polymers in an electrochemical oxidation process. The influence of the A bridge on the stability, luminescent and electrochemical behavior was thoroughly studied. The polymers present an extraordinary stability during multiple n- and p-doping. The experimental results were also investigated theoretically, using DFT approach. For each polymer calculations of the frontier orbital energies and the corresponding Eg value were done using periodic boundary conditions. For polythiophene derived from 1,2-bis-(2,2′-bitiophene-5-yl)ethyne the value of the band gap was also estimated using an oligomeric approximation. Furthermore, the presented compounds revealed an enhanced fluorescent activity, especially in the case of a monomer with bisethynylphenylene bridge and the corresponding polymer.

PHYSICO-CHEMICAL PROPERTIES OF GLYCOGEN FROM THE RAT LIVER AND MUSCLE

As reported previously (6, 7, 8), the glycogen particles from the rat liver and muscle appeared as the specific forms of spheroidal branching bodies. The branching structures were more clearly demonstrated in the glycogen particles from the fasted animal and these appearances were different from the aggregated structures. The chemical and physico-chemical properties of glycogens from the rat liver and muscle are demonstrated and discussed in this paper.1. End group assay of the glycogens and β-amylase digestion degree suggested that the average chain length of the liver glycogen was longer than the muscle glycogen.2. The viscosity of glycogen, measured by varing the temperature from 10°C to 70°C, showed the non-aggregated structure of the glycogen. particles.3. The optical rotartory dispersion and circular dichroism spectra of the glycogen were measured using an addition of iodine solution, and only the muscle glycogen showed the Cotton effect.4. The sedimentation coefficient of the liver glycogen showed the larger s value than the muscle one, and the relationship between s value and concentration of the glycogen was discussed.

II. Contributions towards the history of thiobenzamide

When a stream of sulphuretted hydrogen is passed through a solution of benzonitrile in alcoholic ammonia, the liquid, after the lapse of a few hours, deposits fine yellow needles, which are the thiobenzamide, C 7 H 7 NS = C 7 H 5 S} N H} N H} N, discovered by M. Cahours. It can be obtained in a pure state by recrystallization from boiling water. When a cold saturated alcoholic solution of this body is mixed with an alcoholic solution of iodine, the latter is immediately decolorized with separation of sulphur. If the addition of iodine solution be continued until even after a short boiling free iodine remains, which can readily be detected by starch-paste, the solution filtered from the sulphur, and poured into water, solidifies to a mass of white interlaced needles, which can readily be freed from adhering hydriodic acid by washing with cold water.