Modulation of silica layer properties by varying the granulometric state of tetraethyl orthosilicate precursor aerosols during combustion chemical vapor deposition (CCVD)

Abstract

For the purpose of silica surface layer modulation, a pneumatic-controlled two-substance atomizer with inertia-based coarse droplet separation was operated at different system pressures for tetraethyl orthosilicate precursor aerosol supply during combustion chemical vapor deposition. A comprehensive testing study was performed to characterize the atomizer’s performance characteristics, initial precursor aerosols at the atomizer’s outlet, transformed aerosols before combustion, combustion aerosols and formed layers. Laser diffraction spectrometry, differential electrical mobility analyses and condensation particle counting were used for aerosol characterization with regard to particle size and particle production quantities. Layers were characterized by scanning electron microscopy, atomic force microscopy, spectral ellipsometry, water contact angle measurements and light transmission concerning geometric properties (thickness, surface structure and roughness) and physical behaviors (i.e., optical behaviors, hydrophobicity). Results show a quasi-linear relationship of the ejection mass flow of the pneumatic-controlled atomizer and geometric layer properties which again show a direct relationship to the physical properties. No correlation was found between the aerosols before combustion and the combustion aerosols since the majority of combustion aerosol particles are synthesized solely from the gas phase based on evaporated precursor material.

Copyright © 2020 American Association for Aerosol Research     

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.     

BSA Hydrogel Beads Functionalized with a Specific Aptamer Library for Capturing Pseudomonas aeruginosa in Serum and Blood

Systemic blood stream infections are a major threat to human health and are dramatically increasing worldwide. Pseudomonas aeruginosa is a WHO-alerted multi-resistant pathogen of extreme importance as a cause of sepsis. Septicemia patients have significantly increased survival chances if sepsis is diagnosed in the early stages. Affinity materials can not only represent attractive tools for specific diagnostics of pathogens in the blood but can prospectively also serve as the technical foundation of therapeutic filtration devices. Based on the recently developed aptamers directed against P. aeruginosa, we here present aptamer-functionalized beads for specific binding of this pathogen in blood samples. These aptamer capture beads (ACBs) are manufactured by crosslinking bovine serum albumin (BSA) in an emulsion and subsequent functionalization with the amino-modified aptamers on the bead surface using the thiol- and amino-reactive bispecific crosslinker PEG₄-SPDP. Specific and quantitative binding of P. aeruginosa as the dedicated target of the ACBs was demonstrated in serum and blood. These initial but promising results may open new routes for the development of ACBs as a platform technology for fast and reliable diagnosis of bloodstream infections and, in the long term, blood filtration techniques in the fight against sepsis.     

Response surface methodology for predicting quality characteristics of beef patties added with flaxseed and tomato paste

Response surface methodology was used to study the effect of flaxseed flour (FS) and tomato paste (TP) addition, from 0 to 10% and 0 to 20% respectively, on beef patty quality characteristics. The assessed quality characteristics were color (L*, a*, and b*), pH and texture profile analysis (TPA). Also, sensory analysis was performed for the assessment of color, juiciness, firmness, and general acceptance. FS addition reduced L* and a* values and decreased weight loss of cooked products (P < 0.05). An opposite effect was observed when TP was added (P < 0.05). All TPA parameters decreased when percentages of FS and TP were increased in the formulation of beef patties. Furthermore, FS and TP addition adversely affected the sensory characteristics of the cooked product (P < 0.05); nevertheless, all sensory characteristics evaluated had an acceptable score (> 5.6). Thus FS and TP are ingredients that can be used in beef patty preparation.     

Identification of important image features for pork and turkey ham classification using colour and wavelet texture features and genetic selection

A method to discriminate between various grades of pork and turkey ham was developed using colour and wavelet texture features. Image analysis methods originally developed for predicting the palatability of beef were applied to rapidly identify the ham grade. With high quality digital images of 50–94 slices per ham it was possible to identify the greyscale that best expressed the differences between the various ham grades. The best 10 discriminating image features were then found with a genetic algorithm. Using the best 10 image features, simple linear discriminant analysis models produced 100% correct classifications for both pork and turkey on both calibration and validation sets.     

Influence of the corrosion products of copper on its atmospheric corrosion kinetics in tropical climate

In the present paper, the identification of the corrosion product phases formed on copper under different atmospheres of Cuban tropical climate is reported. Cuprite (Cu₂O), paratacamite (Cu₂Cl(OH)₃), posnjakite (Cu₄SO₄(OH)₆ · 2H₂O) and brochantite (Cu₄SO₄(OH)₆) were the main phases identified by X-ray diffraction (XRD) analysis and Fourier transform infrared spectroscopy (FTIR).Copper corrosion products are known to have a protective effect against corrosion. However, a different behaviour was obtained under sheltered coastal conditions. This can be due to the corrosion products morphology and degree of crystallisation, rather than their phase composition. A higher time of wetness and the accumulation of pollutants not washed away from the metal surface can also play an important role.     

Cellular Antisense Activity of PNA–Oligo(bicycloguanidinium) Conjugates Forming Self‐Assembled Nanoaggregates

A series of peptide nucleic acid–oligo(bicycloguanidinium) (PNA–BG_n) conjugates were synthesized and characterized in terms of cellular antisense activity by using the pLuc750HeLa cell splice correction assay. PNA–BG₄ conjugates exhibited low micromolar antisense activity, and their cellular activity required the presence of a hydrophobic silyl terminal protecting group on the oligo(BG) ligand and a minimum of four guanidinium units. Surprisingly, a nonlinear dose–response with an activity threshold around 3–4 μM , indicative of large cooperativity, was observed. Supported by light scattering and electron microscopy analyses, we propose that the activity, and thus cellular delivery, of these lipo‐PNA–BG₄ conjugates is dependent on self‐assembled nanoaggregates. Finally, cellular activity was enhanced by the presence of serum. Therefore we conclude that the lipo‐BG‐PNA conjugates exhibit an unexpected mechanism for cell delivery and are of interest for further in vivo studies.     

Surface chemistry of phosphorus-containing carbons of lignocellulosic origin

Activated carbon adsorbents were prepared by phosphoric acid activation of fruit stones in an argon atmosphere at various temperatures in the 400-1000 °C range and at different acid/precursor impregnation ratios (0.63-1.02). The surface chemistry of the carbons was investigated by elemental analysis, cation exchange capacity (CEC, measured by neutralization of NaOH with acidic surface groups), infrared spectroscopy and potentiometric titration. Porous structure was derived from adsorption isotherms (N₂ at −196 °C and CO₂ at 0 °C). It was demonstrated that all carbons show considerable cation exchange capacity, the maximum (CEC = 2.2 mmol g⁻¹) being attained at 800 °C, which coincides with the maximum contents of phosphorus and oxygen. The cation exchange properties of phosphoric acid activated carbons from fruit stones are chemically stable in very acidic and basic solutions. Proton affinity distributions of all carbons show the presence of three types of surface groups with pK at 2.0-3.3, 4.6-5.9 and 7.6-9.1. These pK ranges were ascribed primarily to: (a) phosphorus-containing and carboxylic groups; (b) lactonic groups, and (c) phenolic groups, respectively. Phosphoric acid activated carbons are microporous with a relatively small contribution of mesopores. A maximum BET surface area of 1740 m² g⁻¹ was attained at 400 °C.