Characterization of Glass Beads Surface Modified with Ionic Surfactants

Knowledge of the wetting characteristic of mineral surfaces is very important in enhancing the efficiency of separation of valuable minerals from gangue using froth flotation or oil agglomeration. In this paper a capillary rise technique was used to characterize the glass beads surface modified with cationic surfactant. The glass microspheres were used as model particles with a spherical shape and smooth surface to eliminate the roughness effect. The value of the contact angle for water was found to be 21.5 for unmodified beads, and 61.8, 89.7, 68.4 for 0.1, 1.0, 10 mg/g_solid of CTAB, and 39.8, 68.6, 87.9 for 0.1, 1.0, 10 mg/g_solid of DDAHCl, respectively. Data revealed that the adsorption of surfactant onto glass beads decreased the value of the electron donor component, γ-, which defines the hydrophobicity of the surface. Also, the property of the surface was investigated by flotation and oil agglomeration experiments. It was observed that particles with low value of contact angle for water and high for 1-bromonaphthalene and low value of γ- were floated with a recovery equal to 91.1 and 83.1% for CTAB and DDAHCl, respectively, and effectively agglomerated. This indicates that the capillary rise method can be successfully used to predict the wetting properties of solid particles in mineral processing.     

On the Dependence of Prion and Amyloid Structure on the Folding Environment

Currently available analyses of amyloid proteins reveal the necessity of the existence of radical structural changes in amyloid transformation processes. The analysis carried out in this paper based on the model called fuzzy oil drop (FOD) and its modified form (FOD-M) allows quantifying the role of the environment, particularly including the aquatic environment. The starting point and basis for the present presentation is the statement about the presence of two fundamentally different methods of organizing polypeptides into ordered conformations—globular proteins and amyloids. The present study shows the source of the differences between these two paths resulting from the specificity of the external force field coming from the environment, including the aquatic and hydrophobic one. The water environment expressed in the fuzzy oil drop model using the 3D Gauss function directs the folding process towards the construction of a micelle-like system with a hydrophobic core in the central part and the exposure of polarity on the surface. The hydrophobicity distribution of membrane proteins has the opposite characteristic: Exposure of hydrophobicity at the surface of the membrane protein with an often polar center (as in the case of ion channels) is expected. The structure of most proteins is influenced by a more or less modified force field generated by water through the appropriate presence of a non-polar (membrane-like) environment. The determination of the proportion of a factor different from polar water enables the assessment of the protein status by indicating factors favoring the structure it represents.     

Solubility and Aggregation of Selected Proteins Interpreted on the Basis of Hydrophobicity Distribution

Protein solubility is based on the compatibility of the specific protein surface with the polar aquatic environment. The exposure of polar residues to the protein surface promotes the protein’s solubility in the polar environment. The aquatic environment also influences the folding process by favoring the centralization of hydrophobic residues with the simultaneous exposure to polar residues. The degree of compatibility of the residue distribution, with the model of the concentration of hydrophobic residues in the center of the molecule, with the simultaneous exposure of polar residues is determined by the sequence of amino acids in the chain. The fuzzy oil drop model enables the quantification of the degree of compatibility of the hydrophobicity distribution observed in the protein to a form fully consistent with the Gaussian 3D function, which expresses an idealized distribution that meets the preferences of the polar water environment. The varied degrees of compatibility of the distribution observed with the idealized one allow the prediction of preferences to interactions with molecules of different polarity, including water molecules in particular. This paper analyzes a set of proteins with different levels of hydrophobicity distribution in the context of the solubility of a given protein and the possibility of complex formation.     

Formation of Mixed Bond‐Angle Linkages in Zinc Boromolybdate Glasses

The short and medium range structure of glassy MoO₃–ZnO–B₂O₃ has been studied by neutron diffraction and reverse Monte Carlo simulation. The partial atomic pair correlation functions and coordination numbers are presented that are not yet reported for this system. We have established that the first neighbor distances do not depend on concentration within limit of error, the actual values are r_B‐O = 1.38 Å, r_Mo‐O = 1.72 Å, and r_Zn‐O = 1.97 Å. It is found that ZnO takes part in the glassy structure as network former, as ZnO₄ tetrahedral are linked both to MoO₄ and to BO₃ and BO₄ groups. It is revealed that BO₄/BO₃ increases with increasing B₂O₃ content. We have found that only small amount of boroxol ring is present, BO₃ and BO₄ groups are organized into superstructure units, and a small part is in isolated BO₃ triangles. The BO₃ and BO₄ units are linked to MoO₄ or ZnO₄ forming mixed ^[4]Mo‐O‐^[3]B, ^[4]Mo‐O‐^[4]B, ^[4]Mo‐O‐^[4]Zn, ^[3]B‐O‐^[4]Zn, ^[4]B‐O‐^[4]Zn bond linkages.     

Reactive inkjet printing of polyethylene glycol and isocyanate based inks to create porous polyurethane structures

Reactive inkjet printing offers a direct way to create polymeric structures in situ on a substrate. Therefore, two component polyurethane formulations can be utilized to be used in multicomponent inkjet printing. In this contribution, the use of polyethylene glycol (M = 200 g mol⁻¹), glycerol ethoxylate (M = 1,000 g mol⁻¹), and water (blowing agent) in combination with aliphatic 1,6-hexamethylene diisocyanate or aromatic methylene diphenyl diisocyanate for reactive inkjet printing is evaluated. The inks are jettable on a Dimatix DMP-3000 inkjet printer using a 10 pL piezo driven drop-on-demand printhead showing stable droplet formation. Solid films on glass are formed using a drop-by-drop printing strategy. Layer-by-Layer strategy gives best results on polycarbonate substrates forming porous polyurethane structures. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46977.     

Recycling von marinen Sekundärrohstoffen

As a waste product, oyster shells pose a major environmental pollution problem and the reuse of the material is becoming increasingly important. Since the comminution process in the recycling of secondary raw materials defines the properties of the material, oyster shells were grinded using a planetary ball mill and an impact mill and the fractions obtained were analyzed in terms of size and shape and compared with each other. A comminuted material from the impact mill was used for a series of wetting experiments, which helped to demonstrate the surface free energy of the material.     

Syndiospecific polymerization of propene under different processes with different bridged [(RPh)2C(Cp)(2,7-BuFlu)]ZrCl2 metallocene catalysts

The synthesis of syndiotactic polypropene was achieved by using new C_S-symmetric ansa-metallocene catalysts of the type [Ph′₂C(Cp)(2,7-^tertBu₂Flu)]ZrCl₂ (Ph′₂=Ph₂, (4-MePh)₂, 3,4′-Me₂Ph₂, (4-OCH₃Ph)₂). Applying these catalysts, the influence of the substitution pattern of the bridge on the polymerization performance can be studied and highly syndiotactic polypropene (rrrr>99%) with high molar masses and high melting temperatures (up to 153 °C) was obtained.Propene was polymerized at different temperatures under four sets of conditions: in toluene solution, bulk, toluene slurry, and gas phase with NaCl as stirred bed material. Methylaluminoxane (MAO) and methylaluminoxane supported on silicagel (MAO/SiO₂) were used as cocatalyst, respectively. In order to estimate the influence of the process on the single site properties of the catalysts, comparisons were made between polymer properties, i.e. microstructure, melting temperature, molar mass, and polymer morphology, thus allowing the effect of the support on the catalyst to be observed.     

Central limit theorem for reducible and irreducible open quantum walks

In this work we aim at proving central limit theorems for open quantum walks on \({\mathbb {Z}}^d\). We study the case when there are various classes of vertices in the network. In particular, we investigate two ways of distributing the vertex classes in the network. First, we assign the classes in a regular pattern. Secondly, we assign each vertex a random class with a transition invariant distribution. For each way of distributing vertex classes, we obtain an appropriate central limit theorem, illustrated by numerical examples. These theorems may have application in the study of complex systems in quantum biology and dissipative quantum computation.     

Information technology in Nigerian banks: The limits of expectations

In the last ten years, banks in developed countries have been investing more and more in information technology (IT) as a means to reduce costs and improve operational efficiency. An investigation of the application of IT in Nigerian banks was carried out in order to determine the expectations and success of IT implementations in the sector. The data were generated from a survey of randomly selected branches of 56 banks in Lagos, the commercial capital of Nigeria. Almost all the banks had an IT policy, the main thrusts of which where to achieve full application of IT, to be able to meet organisational goals, to secure competitive advantage, and to be up to date. Only 54.6% of them actually achieved some measure of successful implementations. The expected benefits of investment in IT were realised in only a relatively few number of banks. The consequence was that less than 40% of the banks were poised to maximise the benefits of IT through major investments, especially in the areas of online access and transactions, electronic commerce, and electronic publishing. It is estimated that at least 60% of the branches of these banks are spending less than $150,000 annually on IT. An upsurge of investment is, however, expected, first by the banks that style themselves as progressive and have already made some success in IT implementations, and later by the other banks.     

Ultraviolet photodetectors and readout based on a-IGZO semiconductor technology

In this work, real-time ultraviolet photodetectors are realized through metal–semiconductor–metal (MSM) structures. Amorphous indium gallium zinc oxide (a-IGZO) is used as semiconductor material and gold as metal electrodes. The readout of an individual sensor is implemented by a transimpedance amplifier (TIA) consisting of an all-enhancement a-IGZO thin-film transistor (TFT) operational amplifier and a switched capacitor (SC) as feedback resistance. The photosensor and the transimpedance amplifier are both manufactured on glass substrates. The measured photosensor possesses a high responsivity R , a low response time t _{R E S} , and a good noise equivalent power value NEP .