Physicochemical Bond Research Articles

Improvements to the separation centrifuge fat from pork rinds

The aim of the study is to improve the centrifuge for separating fat from pork rinds. In this article, we will consider a centrifuge for separating fat from flakes for feed flour for animal husbandry. In the food industry, heterogeneous systems are separated by centrifugation.In meat processing plants, products entering centrifugation are structureless or structured colloidal-dispersed systems (liquid or flexible bodies) or bulk bodies. The latter include products consisting of a set of solid homogeneous particles of a smaller size that do not take into account the tensile load. It is known that colloidal substances have redundancy in specific gravity and internal surface, therefore they have high adsorption properties and the ability to absorb a large amount of moisture. Colloidal products entering centrifugation separate the liquid contained in them into free and bound. However, such a classification cannot give a clear character of the mechanism of communication between the liquid and the material and does not take into account the specifics of the material itself. A fairly correct and mostly accurate picture of the relationship between a liquid and a material can be shown by a diagram of the forms of communication between a material and a liquid, the structure of which is based on the intensity of the bonds between the material and the liquid. According to these data, there are three forms of material-liquid bonding: chemical, physico-chemical and mechanical bonding. The chemical bond is stronger, and in this case the release of liquid from the material can be achieved by chemical interaction or by intense thermal action (heating). The physico-chemical bond of the liquid with the material can be observed in adsorption, osmotic and structural bonds. The liquid adsorptively bound to the material is separated by evaporation, desorption – during osmotic contact-by the formation of an extracellular concentrated solution. The liquid with structural bonds is mechanically held by the material, and its molecular layer is adsorptively bound. To separate the liquid having a structural connection with the material, methods of evaporation, pressing, fractional centrifugation or structural destruction are used.

Temperature responsive hydrogels for biomedical applications

Hydrogel is a three-dimensional communicator for water-insoluble chemicals. The hydrogel can swell structurally with water and contain large amounts of water. Hydrogel is a chemical or physicochemical bond in different polymer chains. Hydrogels are due to their high water content, softness, flexibleness, and biocompatibility. Hydrogels have therefore become increasingly popular. Hydrogels are created by physically or chemically complex natural and human hydrophilic polymers. When an environmentally specific stimulus is specific to the hydrogel, the gel replaces with solutions. Part of the advantage of universal action by thermo-responsive hydrogels is that they show their activity without the charge of any additional external factors. These hydrogels are attractive for specific medical applications because they can swell in place under physiological conditions and facilitate administration. Due to the combination of distinctly different properties of temperature-sensitive durability through joined domains and the high chemical conversion reactivity of nonmaterial, the application of temperature-sensitive hydrogels with the ion-exchange region for nanoscale chemical conversion reactions is an emerging and enticing alternative niche. The protection and direct fabrication of reactive palladium nanoparticles in temperature-responsive hydrogel networks are defined.

Therapeutic properties of glass-ionomer cements: Their application to orthodontic treatment.

Fluoride has been shown to be an effective agent in the prevention of caries during orthodontic treatment. Resin-modified glass-ionomer cements possess therapeutic anticariogenic properties acting as a fluoride reservoir and releasing fluoride into the environment, particularly at low pH where there is a threat of enamel demineralisation and white spot lesions (WSL's). Patient compliance to instructions in standard oral hygiene measures limits the success of caries prevention and the routine use of glass-ionomer cements can mitigate the lack of compliance, although RMGIC's are not a panacea against WSL's. The adhesion of GIC's to the enamel surface is a physicochemical bond rather than a mechanical bond which reduces the risk of iatrogenic damage to the enamel when bonding and debonding attachments. RMGIC's can be recommended as a bonding adhesive for all attachments but one needs to be selective when bonding molar attachments to avoid occlusal interferences as masticatory forces can be high in these areas.

Usage of glass ionomer cements for reconstructions in the head region

Glass ionomer cements are a two-component hybrid material, consisting of inorganic glass particles, surrounded by an insoluble hydrogel matrix. They are a group of materials based on the acid/ base reaction between poly (alkenoic) acid and an ion-leachable silicate glass. Their biocompatibility, osteoconductive behavior, and ability to bond to bone and metals have generated interest in the material for medical applications. GIC are widely used in dental medicine as an obturation material in primary teeth for treatment and prophylaxis of dental caries, because they have the ability to create a physicochemical bond to tooth structure and to release fluoride. They are currently frequently used in otological and neuro-otological surgery. Apart from ossicular chain reconstruction, they are used for repair of tegmen defects, outer ear canal reconstruction, mastoid obli teration, and stabilization of some hearing prostheses.

Gold nanoparticles physicochemically bonded onto tungsten disulfide nanosheet edges exhibit augmented plasmon damping

Augmented plasmonic damping of dipole-resonant gold (Au) nanoparticles (NP) physicochemically bonded onto edges of tungsten disulfide (WS2) nanosheets, ostensibly due to hot electron injection, is quantified using electron energy loss spectroscopy (EELS). EELS allows single-particle spatial resolution. A measured 0.23 eV bandwidth expansion of the localized surface plasmon resonance upon covalent bonding of 20 nm AuNP to WS2 edges was deemed significant by Welch’s t-test. Approximately 0.19 eV of the measured 0.23 eV expansion went beyond conventional radiative and nonradiative damping mechanisms according to discrete dipole models, ostensibly indicating emergence of hot electron transport from AuNP into the WS2. A quantum efficiency of up to 11±5% spanning a 7 fs transfer process across the optimized AuNP-TMD ohmic junction is conservatively calculated. Putative hot electron transport for AuNP physicochemically bonded to TMD edges exceeded that for AuNP physically deposited onto the TMD basal plane. This arose from contributions due to (i) direct physicochemical bond between AuNP and WS2; (ii) AuNP deposition at TMD edge sites; and (iii) lower intrinsic Schottky barrier. This improves understanding of photo-induced doping of TMD by metal NP which could benefit emerging catalytic and optoelectronic applications.

Laser-Induced Surface Texturing of Metal or Organic Substrates for Structural Adhesive Bonding

Laser-matter interaction is commonly described regarding three main factors: laser beam, materials and environment. Conversion of absorbed energy via collision process into heat is the most important effect that occurs during laser interaction. Short-pulsed laser beam induces fast transition from the overheated liquid to a mixture of vapor and drops which allows the ablation of micrometric layers. Specific patterns can then be achieved using scanning and automation technology also called laser texturing. New materials with specific properties such as endurance life and/or lower environmental impact attract emerging technologies such as thermal spraying. However, adhesive bond strengths have to be high enough to play a key role in surface properties. A clean surface to enhance mechanical interlocking is a key element. Mechanical and physico-chemical bond strength for thick coatings elaborated by thermal spray process can then be developed using laser. The aim of the present paper is to show the potential of such emerging treatments through new results using various thermal spray processes (thermal spraying as well as cold spraying). Metal or organic materials were investigated implementing various powders.

Novel Bone-Like Porous Glass Coatings on Al<sub>2</sub>O<sub>3</sub> Prosthetic Substrates

Over the last two decades, the philosophy behind an optimal fixation of orthopaedic implants progressively evolved towards “bone-conservative” solutions and, accordingly, the researchers’ attention moved from simple mechanical fixation of the prosthesis to host bone by using screws or acrylic cement to new strategies based on a physico-chemical bond (surface modification) in order to minimize bone resection/loss and maximize tissue-implant integration. This research work explores the feasibility of a novel bioceramic single-piece acetabular cup for hip joint prosthesis that can be anchored to the patient’s pelvic bone by means of a bone-like trabecular coating (scaffold) able to promote implant osteointegration.

Interfacial Adhesion between Thermal Spray Coating and Substrate Achieved by Ultrasonic Finishing

The paper presents a pretreatment of the substrate material prior to the thermal spraying process. The ultrasonic finishing method allowed creation of a rolling topography comprising alternating projections and cavities, compressive stress, and increase of the number of defects on the surface. Optical profilometry and metallographic analysis allowed detecting of adhesion zones which form a strong physicochemical bond at the interface between the coating and the substrate material. This interfacial adhesion should provide a firm adhesion strength in end products.

Crack Resistance of Weld Seals, Hardening Methods and Composite Tools Quality

The paper presents a pretreatment of the substrate material prior to the thermal spraying process. The ultrasonic finishing method allowed creation of a rolling topography comprising alternating projections and cavities, compressive stress, and increase of the number of defects on the surface. Optical profilometry and metallographic analysis allowed detecting of adhesion zones which form a strong physicochemical bond at the interface between the coating and the substrate material. This interfacial adhesion should provide a firm adhesion strength in end products.

Bitumen spreading on calcareous aggregates at high temperature

In hot asphalt applications, the adhesion between bitumen and mineral aggregate is usually described in terms of bitumen surface tension and contact angle of the bitumen over the aggregate. However, the quantification of the physico-chemical bond between bitumen and aggregate under realistic conditions is a nontrivial task. In this work, we designed a high-temperature goniometer to measure the contact angle of liquid bitumen on mineral aggregate substrates. The drop deposition was conducted once the thermal equilibrium between liquid bitumen and aggregate was attained. We monitored the spreading of sessile drops of viscous naphthenic bitumen and asphaltic bitumen on polished sheets of calcareous aggregates at high temperature (70–100 °C). A near complete wetting with very low contact angles (13–\(24^{\circ }\)) was reproduced regardless of the bitumen origin and temperature. Furthermore, the coating degree of the naphthenic and asphaltic bitumens on the calcareous aggregates at high temperature was apparently similar. We found that the bitumen-aggregate adhesion is adequately described by dynamic spreading rather than by equilibrium wettability. Spreading kinetics was ruled by the particular properties of each bitumen such as viscosity and acid index. We found evidences of acid etching of the naphthenic bitumen on the calcareous aggregates during spreading at high temperature.

Effect of Ultra-High-Performance Concrete on Pullout Behavior of High-Strength Brass-Coated Straight Steel Fibers

The objective of this research was to investigate the pullout behavior of straight high-strength steel fibers embedded in different ultra-high- performance concretes (UHPCs) with a compressive strength ranging from 190 to 240 MPa (28 to 35 ksi). Particular attention was placed on obtaining matrixes with high packing density to enhance the physicochemical bond with the embedded fiber. The parameters investigated included the use of different sand ratios, silica fume (SF) and glass powder with different mean particle sizes, different superplasticizers, and the addition of hydrophilic or hydrophobic nanosilica particles. Thus, by tailoring the matrix composition, significantly different bond stress versus slip-hardening behaviors were achieved. This is atypical for straight smooth steel fibers, which are normally characterized by a bond-slip softening behavior. Microscopical studies revealed that scratching and delaminating of the brass-coated fiber surface by fine sand and by abrading matrix particles is one reason for this phenomenon, and help explain the maximum equivalent bond strength observed of up to 20 MPa (2.9 ksi).

Histological response of anodized titanium implant

Osseointegration is the essential biological basis of current dental implants. Osseointegration was initially defined on the light microscopic level as “a direct structural and functional connection between ordered, living bone and the surface of a load-carrying implant”. Today, by definition, osseointegtation requires the absence of a fibrous layer and implies that the biological response of the bone is not one of inertness towards a foreign material but rather one of active integration of the material with the bone as part of the body. According to Giavaresi. et al. osseointegration is defined not only as the absence of a fibrous layer around the implant with an active response in terms of integration to host bone, but also as a chemical(bonding osteogenesis) or physico-chemical(connective tissue osteogenesis) bond between implant and bone. Endosseous integration can be deconvoluted into three distinct bony healing phases. The first, osteoconduction, relies on the migration of differentiating osteogenic cells to the implant surface. The second, de novo bone formation, results in a mineralized interfacial matrix equivalent to that seen in cement lines in natural bone tissue. Implant surface design will have a profound effect on osteoconduction, while the surface topography of the implant will play a critical role in bone bonding concomitant with de novo bone formation. The third healing phase, that of bone remodeling, will also, at

Augmentation of facial skeleton with ceramics in congenital disorders and in post-traumatic or postoperative deformities: a preliminary report

The reconstruction of defects of the facial skeleton resulting from congenital faults, tumor removal, or trauma should provide function and form. Synthetic bone substitutes can be used in patients in which autologous bone graft or other operative techniques are contraindicated by the patient’s condition or would not achieve the expected result. The advantages of synthetic substances are obvious: there is no secondary defect due to harvest, and surgery and healing time are therefore reduced. This, together with the shortening of operating and hospital times, reduces costs. A satisfactory result can be achieved in one surgical intervention. Implants are available in the size, volume, and shape required by the anatomical defect; in addition, they are easy to insert, can be stored for long periods, and can be resterilized if necessary. Biocompatible nonresorbable glass ceramics based on oxyfluoroapatite and wollastonite (BAS-0) have been used successfully as a filler or a bone substitute in orthopedics or in maxillofacial surgery since 1991. Surface-active inorganic polycrystalline, nonmetal biomaterial with osteoconductivity, permits osseointegration, i.e., a direct physicochemical bond between live bone tissue and the implant without formation of a fibrous capsule. Compared with hydroxyapatite, it has significantly higher durability to mechanical strain in simulated body fluid and a chemical bond with live bone tissue that is ten- to 100-fold stronger. Due to these features, this material was chosen for restoration of the facial skeletal framework in ten patients in whom other previous solutions had been unsuccessful (contour bone defect with chronic frontal sinusitis developed after open penetrating injury, bone defect after surgery associated with irradiation, significant congenital malformations of the facial skeleton, post-traumatic defects, and postsurgical deformities). The mean time of observation was 6 months. Healing occurred without any adverse reaction or side effect. Two extrusions were solved by secondary surgery. Carefully indicated application of a bone substitute can increase the patient’s quality of life and reduce surgery time and treatment costs.

In vitro cell behavior of osteoblasts on Pyrost bone substitute.

Pyrost bone substitute has been shown to be a promising orthopedic biomaterial. However, little is known about mechanisms that are responsible for the genesis and development of the bond between bone and the Pyrost bone substitute. The purpose of this study is to elucidate the in vitro cell behavior of osteoblasts on Pyrost bone substitute. By using primary culture of rat osteoblasts, the changes in cell morphology during adhesion and flattening onto the surface of Pyrost bone substitute were studied in vitro. At 1 hour, at 3 hours, and at days 1, 3, and 7 after layering, the cell behavior was observed with scanning electron microscope. The processes of trypsinized osteoblast adhesion and spreading on Pyrost bone substitute consisted of 1) contact of rounded osteoblasts with the Pyrost substrate; 2) attachment of osteoblasts at point of contact; 3) centrifugal growth of filopodia; 4) flattening and spreading of the osteoblasts on the Pyrost substrate; 5) division and growth of osteoblasts; and 6) suspension of the osteoblasts across the pores by their processes. These results demonstrated that Pyrost can form a physico-chemical bond with osteoblasts. The Pyrost bone substitute not only supports osteoblasts attachment but also allows proliferation of the osteoblasts.

Restoration of carious lesions of the root.

This paper summarizes and evaluates the indications and limitations of various dental materials and techniques for the treatment and restoration of root surface dental caries. Development of a severity index for classifying and sorting lesions is described. Historical materials such as silver amalgam and gold foil are briefly discussed as are contemporary materials such as composite resins and dentin bonding primers. Emphasis is placed on materials and techniques requiring minimal invasion or preparation of the root surface. Eradication of root lesions by recontouring and smoothing the root surface is discussed at length. A new dental material, glass ionomer cement, which contains fluoride and forms a physicochemical bond with enamel and dentin. and requires no preparation of the root surface other than lesion debridement, is described in detail. Guidelines for managing arrested lesions are offered. In addition, the importance of topical fluoride in the treatment and management of root caries is discussed. Lastly, some suggestions are offered for future directions of research in this area.

The anchoring of glass ceramics of different solubility in the femur of the rat.

A direct physicochemical bond between alkali-rich bioglass or glass ceramic (45 S 5 A and B, Hench) or alkali-poor glass ceramic (KG S, Brömer) and bone has been well documented. Since long-term studies have revealed the interface to be subjected to remodeling of the bone and to increased focal disintegration of the implant, glass ceramics of reduced solubility have been developed by lowering the Na2O content and adding Al2O3, Ta2O5, TiO2, and Sb2O3. Implants of glass ceramic KG S and different compositions with reduced solubility have been studied histologically 14, 29, or 30, 60, 119, and 245 days after implantation in the femur of male Sprague-Dawley rats. Implants of KG S are anchored at an interface with bone connection, which is known to provide for application of considerable shear and tensile strengths; whereas, at the interface of ceramics of reduced solubility, soft tissue, chondroid and osteoid are mainly observed. The dynamics of the events at the interface indicate a disturbance of the transformation of chondroid cells into osteoblasts and of the mineralization of osteoid. This disturbance of pathophysiologic processes during bone healing or bone regeneration is discussed.

Scale formation in sea water distillation plants

It has been shown that techniques of Debye-Scherrer X-ray crystallography, chemical analysis, and metallographic preparation of sections can be used to examine in detail the physical and chemical constitution of the phases present in scales deposited from sea water. Inferences drawn from these examinations indicate that the nature of the physicochemical bond which causes scale to adhere mechanically to heat transfer surfaces is of importance. Experiments in the laboratory are described. The data obtained are discussed in terms of their consequences to the plant designer.