Adhesive Compositions Research Articles

Implant-prosthetic rehabilitation and ectoprosthetics of a patient with an extensive defect of the right orbit. Clinical case. Part 1

During operations for the removal of tumors in the maxillofacial region, aesthetic facial defects and functional disorders are formed: disorders of speech, chewing, swallowing and breathing. Removal of the right eyeball and surrounding tissues after combined treatment of basal cell carcinoma of the right orbit led to the formation of a defect that disrupted the patient’s quality of life. Closing the defect by transplanting a combined flap does not make sense in this case. The manufacture of an ectoprosthesis without supporting elements, taking into account the formed anatomy, does not allow to achieve reliable fixation of the ectoprosthesis. The use of adhesive compositions for fixation in this area is extremely limited and rarely used. Rehabilitation of patients with extensive combined defects of the maxillofacial region is carried out using implant-prosthetic structures. A clinical case of ectoprosthetics of the right orbit is presented with a detailed discussion of all aspects of the design, prototyping and manufacture of the prosthesis.

Tribological behavior under adhesion and dry friction conditions of copper-steel composites manufactured by wire-feed electron beam additive technology

Tribological behavior under adhesion and dry friction conditions of copper-steel composites manufactured by wire-feed electron beam additive technology

Efficacy of different adhesive systems in bonding direct resin composite restorations: a systematic review and meta-analysis.

This study aimed to identify and evaluate scholarly research on the efficacy, durability, and long-term stability of various adhesive systems used for bonding direct resin composite restorations and to identify factors influencing bonding performance, such as adhesive composition, application protocol, substrate type, and etching technique. An all-inclusive electronic database search for peer-reviewed scholarly journal articles was conducted using PubMed, ScienceDirect, Google Scholar, Dimensions, and the Cochrane Library for research articles investigating the effectiveness of different adhesive systems in direct resin composite restorations, excluding reviews, meta-analyses, opinion pieces, and case reports. The risk of bias was assessed using the Cochrane tool (Robvis 2.0). Data were extracted and thematically analyzed, and quantitative data were statistically analyzed using Review Manager software. Dichotomous data were evaluated using the Mantel-Haenszel method, applying a random effects model and 95% confidence interval. The database search yielded 1632 potential articles, of which 14 were included in this study. Several adhesive systems exhibit excellent tensile bond strength. In addition, the type of resin composite, adhesive system, and artificial aging significantly influenced the bonding performance of resin composite restorations. However, the failure rates were low in the different adhesive systems, showing comparable results between the two-step etch-and-rinse and one-step self-etch adhesive systems (p = 0.71). The results showed an overall trend of high bonding effectiveness with a low incidence of adverse events, such as postoperative sensitivity, adhesive failure, and fractures. The study results emphasize the importance of selecting appropriate adhesive systems based on clinical case requirements, restoration characteristics, and patient factors to enhance bonding efficacy, durability, and long-term stability.

Nitrogen-Doped Diamond-like Coatings for Long-Term Enhanced Cell Adhesion on Electrospun Poly(ε-caprolactone) Scaffold Surfaces.

Electrospun poly(ε-caprolactone) (PCL)-based scaffolds are widely used in tissue engineering. However, low cell adhesion remains the key drawback of PCL scaffolds. It is well known that nitrogen-doped diamond-like carbon (N-DLC) coatings deposited on the surface of various implants are able to enhance their biocompatibility and functional properties. Herein, we report the utilization of the pulsed vacuum arc deposition (PVAD) technique for the fabrication of thin N-DLC coatings on the surface of electrospun PCL scaffolds. The effect of N-DLC coating deposition under various nitrogen pressures on the morphological, mechanical, physico-chemical, and biological properties of PCL scaffolds was investigated. It was established that an increase in nitrogen pressure in the range from 5 × 10-3 to 5 × 10-1 Pa results in up to a 10-fold increase in the nitrogen content and a 2-fold increase in the roughness of the PCL fiber surface. These factors provided the conditions for the enhanced adhesion and proliferation of human mesenchymal stem cells (MMSCs) on the surface of the modified PCL scaffolds. Importantly, the preservation of N-DLC coating properties determines the shelf life of a coated medical device. The elemental composition, tensile strength, and surface human MMSC adhesion were studied immediately after fabrication and after 6 months of storage under normal conditions. The enhanced MMSC adhesion was preserved after 6 months of storage of the modified PCL-based scaffolds under normal conditions.

Determination of the main parameters of the modified epoxide oligomer

In order to obtain a high-quality composite material based on the epoxy oligomer that meets the requirements of the operating conditions, research works were carried out in this direction in the dissertation work on obtaining compositions with new quality modified properties based on the modification of the epoxide oligomer with various oligomers. Therefore, ED-20 / MFFO-96/4, ED-20 / SKN-18-1-96/4, ED-20 / MFFO / SKN-18-1-96/2/2, MFFO, SKN-18-1, MFFO / SKN-18-1 and MFFO / . Highly filled compositions based on butadiene-nitrile rubber modified with SKN-18-1 / ED-20 oligomer and oligomer mixtures were prepared and their properties were studied. A number of properties of these obtained adhesive compositions have increased compared to the properties of the composition obtained on the basis of ED-20. For example, strength limit at the moment of breaking, strength of contact with metal on tearing, strength of contact with metal on sliding, strength of contact with wood, resistance to aggressive environments, etc. The influence of fillers (ZnO and dolomite) on the physico-mechanical properties of adhesive compositions was studied and their optimal amounts were determined. It was found that ZnO has a more effective effect than dolomite.

Geometrically engineered organoid units and their assembly for pre-construction of organ structures.

Regenerative medicine is moving from the nascent to the transitional stage as researchers are actively engaged in creating mini-organs from pluripotent stem cells to construct artificial models of physiological and pathological conditions. Currently, mini-organs can express higher-order functions, but their size is limited to the order of a few millimeters. Therefore, one of the ultimate goals of regenerative medicine, "organ replication and transplantation with organoid," remains a major obstacle. Three-dimensional (3D) bioprinting technology is expected to be an innovative breakthrough in this field, but various issues have been raised, such as cell damage, versatility of bioink, and printing time. In this study, we established a method for fabricating, connecting, and assembling organoid units of various shapes independent of cell type, extracellular matrix, and adhesive composition (unit construction method). We also fabricated kidney tissue-like structures using three types of parenchymal and interstitial cells that compose the human kidney and obtained findings suggesting the possibility of crosstalk between the units. This study mainly focuses on methods for reproducing the structure of organs, and there are still issues to be addressed in terms of the expression of their higher-order functions. We anticipate that engineering innovation based on this technique will bring us closer to the realization of highly efficient and rapid fabrication of full-scale organoids that can withstand organ transplantation.

Investigation of two sandwich-structured nanohybrid coating derived from graphene oxide/carbon nanotube on interfacial adhesion and fracture toughness of carbon fiber composites

Designing stronger interphase towards solving the long-standing dilemma of interfacial delamination is critical for stable application of carbon fiber composites. Herein, nano-scale sandwich-structured coatings, where carbon nanotubes (CNTs) were uniformly anchored on both sides of graphene oxide (GO) layer (abbreviated as C/GO/C) and its reverse, that is double GO layers encapsulated CNT network (G/CNT/G in short), were reported around fiber periphery via vacuum filtration method. The effects of surface structure differences on interfacial shear strength (IFSS) and fracture toughness were compared in epoxy matrix. Impressively, composite incorporating G/CNT/G modified fiber delivered prominent IFSS and interfacial fracture toughness of 114.6 MPa and 137.0 J/m2, 105.7 % and 279.5 % increases over control fiber composite. This strategy was also superior to C/GO/C and other reported GO and CNT related works. The main factors for maximal IFSS offered by G/CNT/G are that two GO panels enrich active sites to tightly bridge fiber and epoxy, as well as its layered feature and large surface area provide a stable “skeleton” at interphase for stress transfer. Additionally, the G/CNT/G “skeleton” is closer to sandwich structure of iris leaf, in which the porous CNT intermediate network creates larger deformation and adsorb more energy, leading to peak interfacial fracture toughness.

Universal adhesive systems in dentistry: A narrative review

Background: Various innovative solutions are being adopted in dentistry to reduce the risk of treatment-related complications. Latest-generation adhesive systems are important for preventing microleakages and improving the adhesion of filling materials to tooth structures, resulting in effective use of esthetic restoration materials and long-lasting restorations. Aim: To assess the current use of universal adhesive systems. Materials and methods: The literature search was performed using PubMed, eLIBRARY.RU, and Google Scholar. The following search terms were used: “universal adhesive systems”, “universal adhesives”, “dentin bonding agents”, “dental debonding” and “dental etching”. The search covered studies published during the last 10 years. Results: The initial search yielded 1.284 publications. After screening for compliance with search terms, 106 studies were selected. Following a full-text analysis, 31 (100%) publications were included in the review. Of these, 14 (45%) studies addressed adhesive composition (examined component: hydrophilic monomers, nanofillers, hydrophobic monomers, solvents, etchants); 8 (26%) studies addressed adhesive strength of adhesives (air-powder abrasive surface treatment, smear layer characteristics, surface moisture, bonding agent type, testing conditions); and 9 (29%) addressed application method (etching type). Conclusion: Universal adhesive systems have a wide range of clinical applications (various methods of surface preparation) and clinical scenarios, expanding their potential use. The findings of the literature review describe various applications of universal adhesive systems with various surface preparation techniques, with mixed results. Conflicting literature data highlight the importance of investigating the long-term use of universal adhesives with various clinical settings and protocols.

Spontaneous Encapsulation of Silicon Nanoparticles By Hydroxyl-Rich Graphene Oxide for High Performance Core-Shell Anode Materials

Silicon is one of possible candidate as anode materials for high performance lithium-ion battery (LIB). However, it has several significant drawbacks such as huge volume expansion and formation of unstable surface electrolyte interfaces (SEI) layers. Therefore, carbon-based encapsulation of silicon as an active material is necessary for high performance LIBs. In particular, it plays a role in passivation without side-reaction and conducting path simultaneously as well as formation of core-shell structure. Graphene is one of ideal materials for the application of core-shell structuring with silicon as a carbon material. To date, various surface modification has been introduced such as polymer coating, silane treatment, and oxide coating etc. However, these methods can reduce the electrochemical active area in an electrode due to large amount of residue. Graphene oxide (GO) could be applicable for the reasonable coating on silicon without additives. The GO encapsulated silicon active materials has been introduced because of its homogeneous aqueous dispersion. It is easy and straightforward method. In spite of several advantages of GO encapsulation, the adhesion and stable core-shell structuring of anode composite are still challenging due to post reduction process. It can be affected the adhesion between silicon and graphene. Therefore, strong chemical interaction is necessary for the structuring of anode composites. The spontaneous encapsulation of GO reveals self-assembling silicon nanoparticles with GO via siloxane reactions. This method utilizes the reactive silanol (Si-OH) and siloxane (Si-O-Si) groups on the silicon nanoparticles surface, along with the hydroxyl groups of graphene oxide. In the GO, nucleophilic opening of epoxy rings by pH control leads to the conversion from epoxy to hydroxyl groups. The reactive hydroxyl groups generate new siloxane bonds (G-O-Si) between the silanol and siloxane groups on the silicon surface. The strong adhesion occurs with stable bonding with silicon. The epoxy and hydroxyl rich-GO enhance the chemical interaction. The GO comes from highly crystallized hexagonal surfaces. Therefore, it can be described the representative two advantages with respect to the strong adhesion for composite anode materials and high electrical conductivity as a conducting path. In this work, we introduced preparation of high-quality GO and its application as encapsulation of silicon anode materials. The silicon nanoparticles and high-quality GO anode composite reveals enhanced electrochemical characteristics compared to that of the previous works. It reveals high charge capacity, coulombic efficiency, and cyclic stability. This is a potential approach for high performance anode materials with advanced lithium-ion batteries. This result overcomes the limitations of silicon through effective interfacial bonding, providing higher energy density and cyclic stability in battery applications.

Achieving enhanced electroless Ni-P plating on 6H-SiC substrate through optimization of plasma activation durations

This study explores the impact of plasma activation on the surface properties of 6H-SiC substrates and the subsequent characteristics of electroless nickel‑phosphorus (NiP) plating. The research investigates how varying plasma activation durations influence surface roughness, chemical composition, and plating adhesion. Plasma activation significantly increased surface roughness from 592 nm to 772 nm and the oxidation layer thickness from 5.76 nm to 32.2 nm. These changes were accompanied by corresponding decreases in water and NiP solution contact angles, indicating enhanced surface wettability. The electroless NiP plating demonstrated a progressive increase in surface roughness, and the Ra roughness reached 1319 nm. X-ray diffraction (XRD) analysis revealed a reduction in the crystallinity of the NiP layer, alongside the emergence of new phases such as Ni2P and Ni8P3, indicating alterations in the structural and chemical composition of the plating. The average thickness of the NiP plating decreased from 39.70 μm at 10 min of plasma activation to 36.12 μm at 30 min, suggesting a potential reduction in deposition efficiency with prolonged activation times. Additionally, the hardness of the NiP layer exhibited a decline from 525 HV to 502 HV, attributed to increased surface oxidation and defect formation. The adhesion quality of the plating also deteriorated with increased plasma activation time, as evidenced by significant peeling and cracking, as observed in the scratch test.

Influence of different cavity disinfectants on composite adhesion to dentin of primary teeth: An in vitro study

Restorative treatment is the most common approach to treating dental caries. However, after cavity preparation, some microorganisms may still persist in the substrate, suggesting the use of cavity disinfectants. Nevertheless, their effect on adhesion to composite resins is not yet fully understood, especially in primary teeth. The study aimed to assess the impact of five different cavity disinfectants on dentin adhesion in primary teeth. A total of 60 primary molars were uniformly flattened at their occlusal thirds and randomly allocated into six groups (n = 10 each): Control; Glutaraldehyde; Chlorhexidine; EDTA; Ethanol; Aloe vera. All disinfectants were actively applied, rinsed, and air-dried. The adhesion procedure was carried out according to the manufacturer's instructions, and the restoration was positioned using a mold. Shear bond strength was evaluated. Data were statistically analyzed (One-way ANOVA with Post-hoc Tukey test), with the level of significance set at 5 %. Glutaraldehyde (14.59 ± 3.89 MPa), Chlorhexidine (11.24 ± 2.25 MPa), and EDTA (11.04 ± 2.95 MPa) did not impair the shear bond strength when compared to the Control group (14.95 ± 2.75 MPa). Ethanol and Aloe vera application significantly lowered SBS. The results suggest that Glutaraldehyde, Chlorhexidine, and EDTA can be used as cavity disinfectants. Nevertheless, further in vitro and clinical research is required.

Microdroplet pull-out testing: Significance of fiber fracture results

Fiber reinforced composites are used in structural materials that required light weight and stiffness. The properties of the fibers or matrix are important, but the interfacial properties have a significant impact on the properties of fiber reinforced composite. In this study, the interfacial shear strength (IFSS) was measured using acrylic resin and epoxy resin as base materials. The chemical composition of acrylic and epoxy matrix materials was analyzed to predict the effects on IFSS. Additionally, IFSS was measured through a microdroplet pull-out test. The reliability of the experimental results was enhanced by applying a statistical analysis to IFSS results. In the case of epoxy, GF/epoxy exhibited higher IFSS to twice and half times than CF/epoxy specimens. It means that the surface treatment of the fibers has a significant impact on the interface. In the case of acrylic, IFSS could be measured for GF. But in the case of CF, IFSS was too low to get accurate results of IFSS. Through this research, methods to improve the accuracy of composite interfacial strength measurement experiments were examined, and the study suggested the need for standardized criteria to evaluate composite interfacial adhesion.

Non-standard adhesives for wood-based composites: powder adhesives and bicomponent fibers

Powder adhesives and bicomponent fibres are widely used for composite manufacturing; mainly, they are used for glueing fibres during non-woven production. However, in the woodworking industry, they are rarely used. This study aims to investigate the possibility of powder adhesive and bicomponent fibres utilisation for gluing wood. For this purpose, epoxy-polyester powder adhesive and polyester (PES) bicomponent fibres were selected, and one-component moisture-curing polyurethane adhesive was used as a reference. The selected wood species were spruce, beech, oak and wenge. The differences between powder adhesive- and bicomponent fibre-glued wood joints were observed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX). Mechanical properties of glued wood joints were characterised by tensile shear strength and modelled using finite element modelling (FEM). The adhesives were further characterised using Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The wood joints produced by all combinations of selected wood species and adhesives were comprehensively characterised. The highest values of tensile shear strength were reached by powder epoxy-polyester adhesive (14.85 MPa), whereas joints bonded by bicomponent fibres (5.19 MPa) reached lower values than reference samples.

SYNTHESIS OF THERMOPLASTIC POLYURETHANE USING AROMATIC DIOLS AS A CHAIN EXTENDER AND DEVELOPMENT OF ADHESIVE COMPOSITIONS BASED ON IT

Thermoplastic polyurethane based on oligobutyleneglycoladipinate, 4,4'-diphenylmethanediisocyanate and a chain extender has been synthesized, as which it is proposed to use aromatic diol - 2,2-bis-[4-(2-hydroxyethoxy)phenyl]propane. The synthesis was carried out in a one-step method with a ratio of reagents providing a lack of isocyanate groups. The final product was a linear copolymer with terminal hydroxyl groups. To compare properties using a similar technology, a thermoplastic was obtained in which the role of the chain extension was performed by aliphatic diol - 1,4-butanediol. The sample obtained with the participation of aromatic diol is amorphous, low-modulus and there is no residual deformation after rupture. The use of aliphatic diol leads to the formation of a crystallized high-modulus polymer with high residual deformation and hardness. The observed differences are associated with the introduction of side methyl groups and simple ether bonds into the structure of a rigid polymer block formed by an aromatic diol. The latter violate the ordering of the packaging of macromolecules and increase their ability to elastic recovery. In addition, the content of aromatic fragments in the hard block increases due to the use of aromatic diol. They contribute to the amorphization of the polymer, increase its strength, and also increase the temperature of the beginning of destruction and the coke residue. At the same time, the thermoplastics under discussion are inferior to the analog synthesized using aliphatic diol in terms of temperatures corresponding to the half-life of the decomposition stage and the completion of the decomposition stage. This is due to the presence of in the hard block of the first, relatively non-thermally stable simple ether bonds. On the basis of the proposed thermoplastic, a two-component adhesive has been developed, which, in terms of bonding strength, surpasses household adhesives, which include polyurethane thermoplastic obtained using aliphatic diol. For citation: Bakirova I.N., Mineeva T.A. Synthesis of thermoplastic polyurethane using aromatic diols as a chain extender and development of adhesive compositions based on it. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 11. P. 106-113. DOI: 10.6060/ivkkt.20246711.7040.

Effect of enzymatic chemo-mechanical agents on adhesion of composite resin to dentin of permanent teeth: an in vitro study.

To evaluate and compare the effect of two enzymatic chemo-mechanical caries removal agents with conventional caries removal using rotatory instruments on the adhesion of composite resin to dentin of permanent teeth. The sample comprised 30 permanent molars with caries lesions extending to the dentin, randomly distributed into three groups (n = 10 each): 1-Caries removal with rotary instruments (control group); 2-Caries removal with Papacárie Duo® (F&A Laboratório Farmacêutico, São Paulo, Brazil); 3-Caries removal with Brix 3000™ (Brix S.R.L., Carcarañá, Argentina). After caries removal, the specimens were rinsed and dried. Scotchbond Universal™ adhesive (3M, Saint Paul, Minnesota, USA) was actively applied in self-etch mode and light-cured. Resin composite increments were applied using a silicone mold (3 × 3 × 2mm) and light-cured. Shear bond strength (MPa), work-to-debonding (J/m2), and shear modulus (kPa) were evaluated. For statistical analysis, the level of significance was set at 5%. The control group presented significantly higher shear bond strength values (8.50 ± 2.69MPa) compared to the Brix 3000™ group (5.72 ± 1.55MPa, p = 0.008). There were no significant differences between Papacárie Duo® (6.66 ± 0.86MPa) and the other groups (p > 0.05). Regarding work-to-debonding, the Papacárie Duo® group had a significantly higher result (2944.41 ± 450.21J/m2) than the Brix 3000™ group (1189.41 ± 504.13J/m2, p < 0.001) and the control group (967.10 ± 270.01J/m2, p < 0.001). Concerning shear modulus, the control group showed a significantly higher result (558.67 ± 168.96kPa) than the Brix 3000™ group (339.79 ± 143.78kPa, p = 0.008) and the Papacárie Duo® group (223.04 ± 127.30kPa, p < 0.001). While the application of Papacárie Duo® did not negatively affect composite resin adhesion to dentin of permanent teeth, the application of Brix 3000™ reduced adhesive forces, potentially limiting its clinical use. Further investigations are warranted to elucidate the effects of these materials on dentin substrate, particularly through clinical studies.

Effects of Slurry Composition and Interfacial Adhesion of Monolithic Coatings on FeCrAl Honeycombs

Excellent coating adhesion is a crucial requirement for monolithic catalysts. Within this investigation, a Design of Experiments (DOEs) Taguchi approach was leveraged to construct a 9-factor-3-level matrix encompassing 27 parallel experiments. This framework was employed to scrutinize the pivotal elements influencing the adhesion of FeCrAl metal-based integral coatings, which were prepared using the slurry method. Moreover, an unprecedented endeavor was made to scrutinize the mechanism of coating delamination from the vantage points of macroscopic slurry, microscopic coatings, and nanoscale interfaces. The findings reveal the following: (1) The inclusion of a high-acidity additive (&gt;5%) emerges as one of the pivotal factors in achieving superior adhesion, particularly when the boehmite content exceeds 1%. (2) The existence of binder-filled interstices within the coating, smaller by 1–2 orders of magnitude than the carrier particles, significantly contributes to heightened adhesion. (3) A bonding region of approximately 5 nm is present at the interfaces between carrier particles, resulting in augmented adhesion.

Synchronously enhanced flame retardancy and mechanical properties of polylactic acid via in-situ assembly of polyphosphazene nanoparticles on ammonium polyphosphate

Polylactic acid (PLA) exhibits wide potential applications in many fields ranging from textile, packaging material to biomedical devices. However, the relatively low mechanical properties and inflammability are obstacles to the expansion of its application. Here, a kind of polyphosphazene nanoparticles with tannic acid (TA) as template, hexachlorocyclotriphosphazene (HCCP) and 4,4′-Sulfonyldiphenol (BPS) as comonomers were prepared (named as HTB), and then combined with ammonium polyphosphate (APP) to enhance the comprehensive properties of PLA composites. The introduction of HTB strengthened the interfacial adhesion of composites via constructing the hydrogen bond interaction between PLA and APP, promoting the homogenous dispersion of APP in the composite and the formation of APP network. The flame retardant measurements presented that incorporating 10 wt% APP and 5 wt% HTB in PLA increased the limit oxygen index (LOI) value to 31.0% and endowed the composite with the V-0 rating of UL-94 test and simultaneously, the peak of heat release rate (PHRR) and total heat release (THR) of the composite decreased by 14.2% and 13.2% compared with pure PLA. Specially, there was almost no melt drip appeared during the combustion process, which was distinctly different from the combustion behavior of the composite containing only 20 wt% APP with the V-2 rating of UL-94 test. The uniform dispersion of APP in the PLA matrix and the strong interfacial adhesion between APP and the PLA matrix contribute to the enhancement of the mechanical properties of composites, and the elongation at break, Young’s modulus and impact strength of the composite were increased by 52.9%, 7.6% and 24.2%, respectively. The present study offers novel insights for the trade-off between flame retardancy and mechanical properties with PLA composites.

Tooth fragment reattachment using cyanoacrylate tissue adhesive and flowable composite: An in vitro study

ABSTRACT Aim: Crown fractures in anterior teeth represent 18%–22% of dental hard tissue injuries. Immediate reattachment of the fragment using composite resin is the preferred treatment option. However, the reattached fragments are prone to fracture. The use of topical cyanoacrylate tissue adhesive has been reported for managing painful fractured molar teeth and maxillary incisors. Rural population of India does not have access to basic health care; hence, over-the-counter availability of cyanoacrylate may prove beneficial for reattaching the tooth fragment until a patient receives professional care. The present study aimed to evaluate and compare the methods of fractured fragment reattachment using isoamyl 2-cyanoacrylate tissue adhesive and flowable composite. Methods: Eighty intact human permanent maxillary central incisors were randomly divided into four groups (n = 20). Except for the control Group D, other teeth were cut through the middle third of the crown horizontally. Fragments were reattached using flowable composite in Group A, cyanoacrylate tissue adhesive in Group B, and in Group C fragments were attached using cyanoacrylate tissue adhesive, and filling flowable composite circumferentially in chamfer placed along the fracture line. Fracture resistance was tested using a universal testing machine by applying load to each tooth perpendicular to the line of reattachment from labial to lingual direction. The force required to fracture the tooth was recorded in Newtons, and data were statistically analyzed. Results: The highest fracture resistance was exhibited by Group D, followed by Group A, Group C, and Group B, respectively. There was no statistically significant difference between Groups A and C. Conclusion: Composite remains most efficacious in reattaching fractured fragments to the tooth. However, the use of isoamyl 2-cyanoacrylate followed by composite restoration in chamfer offers comparable bonding. The experimental over-the-counter available isoamyl 2-cyanoacrylate may be useful for reattaching uncomplicated fractured teeth when emergency dental care is inaccessible, and needs to be clinically and esthetically evaluated by a professional. However, this in vitro experiment needs to be evaluated clinically for long-term bond strength and under various intraoral forces.

Rock exfoliation in the unstable formations during underground mine working driving and selection of efficient adhesive compositions for strengthening

Purpose is to identify factors favouring rock exfoliation in roof of underground mine workings while operating Akbakay deposit and determine optimum structure of adhesive reagents for the rock strengthening taking into consideration mineralogical composition of the formation. Methods. The research was carried out in a lab environment. Chemical and ultimate composition of the rock mass samples was determined through x-ray diffraction method; the x-ray phase identification approach helped define their mineralogical composition. The optimum composition of adhesive reagents has been determined based upon the ambient temperature and hardening time. Viscosity durability of the adhesive compounds was assessed using a technique of uniaxial crack of the immovable samples. Statistical data processing involved determination of the required number of the samples to achieve the preset accuracy degree. Findings. Exfoliation of the fragments of both fractured and unstable rocks from Akbakai deposit depends upon availabi-lity of such chemically and mechanically unstable salts as dolomite, albite, and mirror stone. Epoxide reagent in 9 to 1 ratio with polyethylenepolyamine catalyzer has been identified as the most effective adhesive compound. Epoxy adhesives have demonstrated higher cohesive resistance to compare with polyurethane analogues, and better compliance with requirements as for viscosity and hardening time. Originality. Use of epoxy to strengthen both fissured and unstable rocks of Akbakai deposit containing mineral salts, helps increase tensile properties up to three times. Moreover, epoxies also demonstrate high adhesive characteristics; and they are resistant to moisture and temperature attacks being typical for mine environment. New logarithmic dependencies have been identified describing rock mass stability while applying the modified polyurethane with polyethylenepolyamine catalyzer in 9 to 1 ratio. Practical implications. Various types of reagents have been considered for safe and effective strengthening of underground mine workings in the fractured rock masses having a tendency to caving. The proposed adhesive reagents resist efficiently the external share loads and stresses increasing structural stability and safety of rock masses.

Analysis and discrimination of adhesive species using ATR-FTIR combined with Raman, and HS-GC-IMS together with multivariate statistical analysis

Identifying the species and origin of adhesives in criminal investigations aids in narrowing inquiry scope and supporting case detection. This study introduces two advanced combined analytical techniques for distinguishing adhesive species, including attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) combined with Raman spectroscopy, and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) together with multivariate statistical analysis. ATR-FTIR categorized seven adhesives into three groups based on the base materials, with further differentiation achieved via Raman spectra. Analysis of volatile components identified 79 volatile organic compounds (VOCs), with esters being the most concentrated. The fingerprint profile clearly illustrated the characteristic fingerprint sequence and unique marker compounds of each adhesive, effectively enabling their differentiation. Multivariate statistical analysis methods, including principal component analysis (PCA), orthogonal partial least squares-discriminant analysis (OPLS-DA), heatmap, and hierarchical cluster analysis (HCA), were utilized to visually interpret the classification of adhesives. This integrated analytical approach provides a comprehensive analysis of adhesive compositions, facilitating the diversification and precision of adhesive species identification, and broadening the scope for detecting and analyzing trace evidence in forensic science.