Hydrolysis of freshly prepared wheat starch fractions and commercial wheat starch using α-amylase

The enzymic hydrolysis of commercial wheat starch and freshly prepared wheat starch fractions was studied in batch and flow systems. Fresh starch was prepared by wet separation of wheat flour into starch milk and gluten, followed by processing the starch milk using a serially connected hydrocyclone system to produce underflow and overflow streams. The underflow stream consisted mainly of the larger (> 30 w m) granules, while the overflow stream contained only the smaller (< 10 w m) granules. In batch system, the hydrolysis behavior of wheat starch fractions was investigated under the action of Sigma f -amylase ( Bacillus licheniformis ), either as soon as they were prepared or after spray drying. The two fractions of fresh wheat starch showed different hydrolysis behavior, the difference getting larger as the separation improves. Underflow streams were found to be much more susceptible to hydrolysis than overflow streams, regardless of whether the hydrolysis was carried out right away or on dried samples, and also regardless of whether rinsing was applied. In flow system, dried underflow stream and commercialwheat starch were hydrolyzed using Orbamil-T ( Bacillus licheniformis ), Orbamil-BHT ( Bacillus stearothermophilus ), and Sigma f -amylase ( Bacillus licheniformis ). Hydrolysis of fresh starch was found to be significantly faster than commercial wheat starch. Commercial f -amylase Orbamil-T was found to be almost as effective as the purified Sigma f -amylase.     

ON THE HARDENABILITY OF AN INTERCRITICALLY HEAT TREATED MICROALLOYED STEEL

Dual phase steel has become an important engineering material to be used in structural and automotive applications due to its good combination of strength, ductility, and formability. In this study, hardenability of a low carbon and microalloyed steel was investigated by using the standard Jominy End Quench Test at four different quenching temperatures. Three steel specimens were quenched from the intercritical region at 737°C, 754°C, and 779°C separately, whereas one of them was tested at 900°C, in the fully austenitic region. After finishing the Jominy test, metallographic examination of the samples was carried out to see the variation in the microstructure through the length of the steel. And also, hardness measurements were made through the length of the samples. Results brought out that there was a strong decrease in the hardness of the tested samples after a depth of 5 mm from the quenched end.     

Ladder type polymers from dihydroxyaromatic compounds and dialdehydes

Ladder polymers were synthesized by reaction of dihydroxynaphthalene and bisphenols with malondialdehyde and glutardialdehyde. Differential scanning calorimetry and thermogravimetric analysis were used to determine the thermal behaviour of the polymers, and conductivities of two representative polymers were measured. Ladder polymers with higher molecular weights showed better thermal resistance.     

Correction to: Assessment of pick wear based on the field performance of two transverse type roadheaders: a case study from Amasra coalfield

Bulletin of Engineering Geology and the Environment - A Correction to this paper has been published: https://doi.org/10.1007/s10064-021-02153-1     

Modeling and optimization of fine coal beneficiation by hydrocyclone and multi-gravity separation to produce fine lignite clean coal

We evaluated the suitability, contribution to the national economy, and environmental impact of hydrocyclone and Multi-Gravity Separation (MGS) processes using fine-sized coal taken from the Soma coal sludge pond. The lignite coal tailings were treated by a two-stage concentration scheme for the recovery of fine clean coal. Pre-enrichment experiment parameters were determined by the Taguchi experimental design method, and the results were interpreted by the Statistical Packages for the Social Sciences (SPSS) 15.0 program to evaluate the optimum parameter values. The tailings initially contained 54.82% ash and had a LCV of 2,279 kcal/kg; after hydrocyclone pre-enrichment, the concentrate was 42.60% ash and had a calorific value of 2,573 kcal/kg (55.75% coal yield). After the final enrichment process, the ash of the pre-concentrated coal was decreased to 24.21% and left a clean coal with a base calorific value of 3,226 kcal/kg (36.16% coal yield). The total sulfur of the obtained clean coal was 0.52% and the combustible sulfur rate was 0.10%. To reduce the ash content of the obtained clean coal, a decantation process was performed that decreased the ash content to 21.84% and the base calorific value was increased to 4,109 kcal/kg.     

Parametric analysis of flare edge rolling throat bending and asymmetric flare effects for H-plane horn radiator

In this paper, radiation characteristics of H-plane sectoral horn antenna are treated systematically by investigation of main structural design parameters and, flare edge rolling, throat bending and asymmetric flare effects. The analytical regularization method (ARM) is used to solve the problem of E-polarized wave diffraction in a fast and accurate way. The numerical procedure is initially verified by the analytical solutions, and then the calculated directivity gain patterns are demonstrated for the modeled horn antenna configurations. Proper choices of the antenna parameters, such as horn depth, aperture length, feeder waveguide width, flare angle, wall thickness, flare edge rolling and throat bending are proposed for the designers to reach high directivity gain, narrow beam width, suppressed side lobe levels, increased front-to back ratio and improved aperture efficiency.     

Dephytinization of food stuffs by phytase of Geobacillus sp. TF16 immobilized in chitosan and calcium-alginate

In this work, Geobacillus sp. TF16 phytase was separately immobilized in chitosan and Ca-alginate with the efficiency of 38% and 42%, respectively. These enzymes exhibited broad substrate specificity. Maximal relative phytase activity was measured at pH 5.0 and 95°C and pH 3.0 and 75°C for chitosan and Ca-alginate, respectively. The enzymes were highly stable in a wide pH and temperature range. Values of K_m and V_max were determined as 2.38 mM and 3401.36 U/mg protein for chitosan, and 7.5 mM and 5011.12 U/mg protein for Ca-alginate. The immobilized enzymes showed higher resistance to proteolysis. After 4 h incubation, hydrolysis capacities of chitosan- and Ca-alginate immobilized enzymes for soymilk phytate were calculated as 24% and 33%, respectively. The chitosan- and Ca-alginate immobilized phytases conserved its original activity after 8 and 6 cycles of reuse, respectively. The features of the enzymes were very attractive and they might be useful for some industrial applications.     

Processability of PVC plastisols containing a polyhydroxybutyrate‐polyhydroxyvalerate copolymer

Plastisols based on polyvinyl chloride (PVC) can be processed by different techniques; their processability markedly depends on their flow properties and gelation/fusion processes. Classically, PVC has been the only polymer present in plastisol formulations. The present work explored the possibility of adding polyhydroxyalkanoates (PHAs), a type of biopolymer that, according to previous work, exhibits a good miscibility with PVC processed by other techniques (internal mixer and compression molding). The influence of PHA particles on flow properties, gelation‐fusion processes, tensile strength, hardness, and processability by rotomolding was evaluated. Although the biopolymer markedly increased the viscosity of PVC plastisols and caused a decrease in tensile strength in processed specimens, formulations including 20% by weight of biopolymer presented a good thickness distribution in rotomolded items, an elongation at break of around 300%, and an ultimate tensile strength of around 6–7 MPa. J. VINYL ADDIT. TECHNOL.,, 2012. © 2012 Society of Plastics Engineers     

Zinc(II)-Coordination Polymers Based on Isomeric Azo-Containing Anionic and Neutral Linkers

Four mixed-ligand coordination polymers, namely, [Zn(μ-3,3′-Cl₂abdc)(μ-4,4′-azobpy)]_n (1), [Zn(μ-4,4′-Cl₂abdc)(μ-3,3′-azobpy)_0.5(H₂O)]_n (2), [Zn₂(μ-4,4′-Cl₂abdc)(μ₄-4,4′-Cl₂abdc)_0.5(μ-OH)(μ-4,4′-azobpy)]_n (3) and {[Zn(H₂O)₄(μ-4,4′-azobpy)](4,4’-Cl₂abdc)}_n (4) (Cl₂abdc: dichloroazobenzenedicarboxylate and azobpy: azobispyridine) were synthesized with azo-group containing positional isomer anionic and neutral ligands in the presence of Zn(II) ion and characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction. X-ray results showed that the compounds displayed structural diversity depending on disposition of donor groups on ligands and solvent. Compounds 1 and 2 exhibited two-fold and five-fold interpenetrated 2D?→?2D structures, respectively, with the interchanging of positional isomer anionic and neutral ligands. Five-fold polycatenated 2D?→?3D structure was observed with the selection of 4,4′-Cl₂abdc and 4,4′-azobpy in 3. Although same ligands were used in the synthesis of 4 like compound 3, 1D structure of 4 was obtained with the use of DMF:water mixture and zinc nitrate. 4,4′-Cl₂abdc acted as a counter-ion in 4. Furthermore, topologic, thermal, optical and photoluminescence spectra of the compounds were studied in detail.

     

Linkage isomerism for 4-methylimidazole and a new coordination mode of pyrazine-2,3-dicarboxylate ligand in {[Cd(pzdc)(4-mim)(5-mim)2]·½H2O}n coordination polymer

A novel one dimensional coordination polymer of Cd(II)-pyrazine-2,3-dicarboxylate with a new coordination mode of pyrazine-2,3-dicarboxylate ligand (pzdc), {[Cd(pzdc)(4-mim)(5-mim)₂]·½H₂O}_n (1) (4(5)-methylimidazole = 4(5)-mim), has been synthesized and characterized by elemental, thermal analysis, IR spectrum and single crystal X-ray diffraction technique. In complex 1, the Cd(II) ion has a distorted octahedral geometry, in which the pzdc moiety acts as a bridging ligand. Linkage isomerism of the coordinated 4(5)-methylimidazole ligand was observed in 1. The two adjacent one-dimensional chains connected by interchain hydrogen bonds among the N-H groups of methylimidazoles and carboxylate oxygens of pzdc, leading to a three-dimensional framework. The hydrogen bonds account for the coexistence of two unique coordination forms of methylimidazoles in the same coordination sphere.