Chemical Glue Research Articles

Intra-species variation in maximum moisture content, cell-wall density and porosity of hardwoods

Abstract Some properties of wood, such as maximum moisture content, cell-wall density and porosity, are not well known, even though they affect the performance of chemical preservatives, glues and coatings on wood. This knowledge gap was addressed in the present study by analysing these physical properties in laurel (Laurus nobilis L.) wood. Laurel is a common hardwood tree in southern Europe. Seventeen laurel trees were felled for the study, and 300 defect-free specimens were obtained from the trees for analysis. The following mean values were obtained: wood maximum moisture content, 114%; cell-wall oven-dry density, 1198 kg m−3; and oven-dry wood porosity, 45%. Significant inter- and intra-tree variations in the three properties were observed. The inter-tree variation was mainly attributed to the tree age, and the trend suggests that wood maximum moisture content and porosity are expected to be lower in older trees than those under study. The values of the three properties were slightly, but statistically significantly, lower at the highest positions in the tree. Harvesting of the basal logs of young trees is therefore advisable only if more porous wood is required, and commercial exploitation of the whole trunk of mature trees is recommended if more compact wood is required. The variation in cell-wall density was not negligible, although this variable is often assumed to be approximately constant for all wood species. Maximum moisture content and wood porosity can be estimated using bulk or apparent density as a predictor variable.

V-057 INTRAPERITONEAL ONLAY MESH (IPOM) TECHNIQUE FOR THE LAPAROSCOPIC TREATMENT OF INGUINAL HERNIA

Abstract Laparoscopic treatment of inguinal hernia is a widely accepted technique, especially in the case of bilateral or recurrent inguinal hernias. The evolution of materials has led to the successful use of double layer prostheses for the intraperitoneal treatment of wall defects, significantly reducing the mesh-related complications. In this regard, the literature data and the availability of non-absorbable, transparent, light surgical prostheses in polypropylene, composed of a macroporous monofilament mesh and a transparent film, have led to the re-proposal of the IPOM technique also for the treatment of primary inguinal hernias. After the laparoscopic access in the abdomen using a 10 mm trocar in the umbilical region and two 5 mm trocars operating in the Iliac fossae, the hernia is reduced by returning the hernial contents to their original compartments and the hernial sac is closed with the possible lipoma using purse-string suture. Subsequently, a polypropylene composite prosthesis is then inserted into the abdomen, centered on the defect and fixed to the wall by tack and chemical glue. To date we have performed 10 procedures on 6 patients (4 with bilateral hernia). The longest follow-up is one year. The patients were all discharged the day after the surgery, reporting a mean postoperative pain score (assessed with EHS QoL scale) equal to 2 (range: 0–4), and the work resumption after a week in average. This technique, which is easy to perform and reproducible, can significantly reduce operating times and minimize complications related to the preparation of the peritoneal pocket.

Ultra-light MXene/CNTs/PI aerogel with neat arrangement for electromagnetic wave absorption and photothermal conversion

The assembly of Ti3C2Tx MXene into porous three-dimensional (3D) structures is of great significance for the design of MXene-based electromagnetic wave (EMW) absorbing materials. However, the construction of aerogels alone is challenging due to the weak interlayer interaction between the MXene nanosheets. In addition, MXene with high conductivity is often detrimental to the dissipation of EMW. Here, we introduce polyimide (PI) as the “chemical glue” and carbon nanotubes (CNTs) as the impedance mismatch improvement agent, and construct 3D MXene/CNTs/PI aerogel. By controlling the growth of ice peaks, holes are made on the surface. Due to the excellent impedance matching and special microstructure, MXene/CNTs/PI has a minimum reflection loss (RLmin) of −50.03 dB@13.7 GHz, and an effective absorption bandwidth (EAB) of 5.6 GHz. Meanwhile, MXene/CNTs/PI also exhibits significant photothermal conversion performance, which can effectively absorb sunlight and store, convert and utilize it. Therefore, the multifunctional MXene/CNTs/PI has broad application prospects.

Mesh fixation techniques in Lichtenstein tension-free repair: a network meta-analysis.

To compare the clinical effectiveness of different mesh fixation techniques in Lichtenstein tension-free repair using network meta-analysis. Cochrane Library, Medline, EMBASE, and Web of Science databases were searched until 1 December 2020, and randomized controlled trials (RCTs) comparing outcomes between different mesh fixation techniques were included. The primary endpoints were chronic postoperative inguinal pain (CPIP) and hernia recurrence. The second endpoint was seroma and infection. Data were processed using Stata MP16.0, and R x64 3.6.1. The results demonstrated that 32 RCTs (n=6362) were eligible for pooling. Six types of mesh fixation techniques were used: non-absorbable suture, absorbable suture, chemical glue, fibrin glue, self-gripping mesh, and staple fixation. Network meta-analysis indicated that the incidence of CPIP with fibrin glue was lower than that with non-absorbable sutures (relative risk [RR]=0.23, 95% credibility interval [95%CrI] [0.09, 0.50]), absorbable sutures (RR=0.24, 95%CrI [0.08, 0.60]), chemical glue (RR=0.36, 95%CrI [0.13, 0.87]), and self-gripping mesh (RR=0.27 95%CrI [0.09, 0.62]). Self-gripping mesh was superior to non-absorbable sutures (RR=0.44, 95%CrI [0.23, 0.74]) in reducing postoperative infection. This network meta-analysis suggests that fibrin glue might be best for reducing CPIP and recurrence. However, a large-scale RCT is warranted to confirm the results.

Electron Correlation: Nature's Weird and Wonderful Chemical Glue

AbstractIt can be argued that electron correlation, as a concept, deserves the same prominence in general chemistry as molecular orbital theory. We show how it acts as Nature's “chemical glue” at both the molecular and supramolecular levels. Electron correlation can be presented in a general chemistry course in an at least somewhat intuitive manner. We also propose a simple classification of correlation effects based on their length scales and the size of the orbital gap (relative to the two‐electron integrals). In the discussion, we also show how DFT can shed light on wavefunction theory, and conversely. We discuss two types of “honorary valence orbitals”, one related to small core‐valence gaps, the other to the ability of empty 3d orbitals in 2ndrow elements to act as backbonding acceptors. Finally, we show why the pursuit of absolute total energies for their own sake becomes a sterile exercise, and why atomization energies are a more realistic “fix point”.

A pre-clinical animal study of a novel mechanical-only ablation device treatment for superficial venous disease.

Current minimally invasive techniques for ablation in superficial venous reflux are limited to thermal based systems requiring tumescent anesthesia, non-thermal chemical sclerosants and permanent glue implantation. The aim of this feasibility study was to determine the safety and efficacy of a novel mechanical-only ablation (MOA) device called EnVena, in a recognised large animal model with chronic follow up. Venous ablation of six lateral saphenous veins in three sheep was performed using the EnVena device. Luminal patency and vein wall fibrosis were evaluated by histologic analysis at 51 and 89 days. All treated veins demonstrated fibrotic occlusion in contiguous segments at 51 and 89 days on histological analysis. From 45 consecutive segments spanning the treatment length across the six treated veins, 26 (57%) were fully occluded, 7 (16%) were impinged or partially occluded and 12 (27%) were open. There were no device related complications during the follow up period. A purely mechanical approach to superficial venous ablation demonstrated safety and efficacy in a recognized large animal model based on histological findings.

Potato Starch Edible Films as Environmentally Friendly Carriers for Model Drug: In vitro Release Study

Starch is a vital plant polymer used in thousands of food and non-food products. Researchers have made great efforts over the past 20 years to develop ingredients based on nature which enhance starch texture and nutritional values. Starch has many non-food applications, ranging from body care to medicinal applications, among its uses in other foodstuffs. Since starch is sustainable and environmentally friendly material, in many chemical applications, including plastics, detergents and glues, it can serve as a good substitute for fossil-fuel components. This work aims to introduce edible starch films-based carriers for supporting the release of fluorescein as a model drug. Physical modification for potato starch carriers (PSS) was done by incorporating glycerol and low-density polyethylene (LDPE) molecules. Fluorescein dye was incorporated in edible films to investigate the amount of release by UV-vis technique. It was found that PSS-LDPE is spread better than LDPE at physiological temperature and PSS dissolution is also appropriate at this temperature. While PSS formed faster edible film than LDPE and PSS-LDPE, it decayed within 3 days. The amounts of dye released from PSS and PSS-LDPE films were higher than that of fluorescein dispersed in starch suspension in buffer solution (pH 7.5) at 37 o C.

Occupational exposure limits for acetaldehyde, 2-bromopropane, glyphosate, manganese and inorganic manganese compounds, and zinc oxide nanoparticle, and the biological exposure indices for cadmium and cadmium compounds and ethylbenzene, and carcinogenicity, occupational sensitizer, and reproductive toxicant classifications.

Occupational exposure limits for acetaldehyde, 2-bromopropane, glyphosate, manganese and inorganic manganese compounds, and zinc oxide nanoparticle, and the biological exposure indices for cadmium and cadmium compounds and ethylbenzene, and carcinogenicity, occupational sensitizer, and reproductive toxicant classifications.

PREPARATION OF MIXED HYDROGELS BASED ON BIOPOLYMERS AND THE STUDY OF THEIR RHEOLOGICAL PROPERTIES

A well-known, affordable, and cheap method of modifying biopolymers is their simple mixing with synthetic and natural polymers. As a result, similar to metal alloys, polymer-polymer complexes with predetermined properties can be obtained. Although interpolymer complexes became a subject of study and application a long time ago, in domestic practice, the study of natural biopolymers is limited. The purpose of this study was to present and study the issue of structuring in solutions of bio- and synthetic polymers, as with a low dry matter content such structures have many properties of a solid. Natural ampholytic polymers are polyelectrolytes, which is also of great importance for their further study. By analyzing the results of studies of complexes formed by a synthetic linear polyelectrolyte with a charged partner – protein, it becomes possible to create new “smart” polyelectrolyte complexes that can undergo phase changes in narrow, controlled pH ranges. The positive effect of sodium carboxymethyl cellulose on the gelation of 5% gelatine hydrogels was established. It was determined that the presence of additives of inorganic salts leads to an increase in the swelling of gelatine gels. It was established that more durable gels are less prone to aging. The practical significance of these studies is determined by the fact that in many industries (food, soap, paint, and varnish), it is necessary to obtain structures with tailor-made properties. Gel formation may also be an undesirable phenomenon that must be prevented, for example, in the production of chemical fibers, glues, and tanning solutions. Furthermore, biological objects themselves in most cases, by their nature, are protein gels with specific mechanical properties. Keywords: structure and dynamics of gelatine mixed hydrogels, adsorption on solid surfaces, collapse of heterogeneous networks, swelling and aging of mixed gelatine hydrogels.

Anisotropic Electromagnetic Absorption of Aligned Ti3C2Tx MXene/Gelatin Nanocomposite Aerogels.

Assembling Ti3C2Tx MXene nanosheets into three-dimensional (3D) architecture with controllable alignment is of great importance for electromagnetic wave absorption (EMA) application. However, it is a great challenge to realize it due to the weak van der Waals interconnection between MXene nanosheets. Herein, we propose to introduce gelatin molecules as a "chemical glue" to fabricate the 3D Mxene@gelatin (M@G) nanocomposite aerogel using a unidirectional freeze casting method. The Ti3C2Tx MXene nanosheets are well aligned in the M@G nanocomposite aerogel, yielding much enhanced yet anisotropic mechanical properties. Due to the unidirectional aligned microstructure, the M@G nanocomposite aerogel shows significantly anisotropic EMA properties. M@G-45 shows a -59.5 dB minimum reflection loss (RLmin) at 14.04 GHz together with a 6.24 GHz effective absorption bandwidth in the parallel direction (relative to the direction of unidirectional freeze casting). However, in the vertical direction of the same M@G aerogel, RLmin is shifted to a much lower frequency (4.08 GHz) and the effective absorption bandwidth decreases to 0.86 GHz. The anisotropic electromagnetic energy dissipation mechanism was deeply investigated, and the impendence match plays a critical role for electromagnetic wave penetration. Our lightweight M@G nanocomposite aerogel with controllable MXene alignment is very promising in EMA application.

Biopotential Measurement of Plant Leaves with Ultra-Light and Flexible Conductive Polymer Nanosheets

Abstract This study demonstrates the feasibility of free-standing conductive polymer nanosheets (referred to hereafter as “conductive nanosheets”) as bioelectrodes for plant leaves. The conductive nanosheet exhibited ultra-conformability and physical adhesion to unevenly structured surfaces, such as the veins of a plant leaf, without the use of chemical glue, owing to the ultra-thin and light structure (300 nm thick, 150 µg). The conductive nanosheet coupled with a Bluetooth system enabled wireless biopotential measurement of plant leaves (Angelica keiskei Koidzumi) up to approximately 1500 h, while conventional bioelectrodes such as pre-gel electrodes caused discoloration during the measurement, owing to the acrylic glue utilized for adhesion. We also discovered that the biopotential pattern was altered under periodic light-emitting diode (LED) irradiation. Such minimally invasive measurements using the conductive nanosheets can pave the way for a revolutionary method to analyze the bioactivity of plants in the application of agriculture and food science.

Dust removal device for waterless solar photovoltaic panel

With the rapid development of human science and technology, energy consumption is becoming increasingly severe, and solar energy, which is one of the clean energy in the future, has attracted wide attention. However, while solar photovoltaic power stations bring huge economic benefits, a huge problem about the cleaning and protection of solar photovoltaic power generation panels has also arisen [1]. The photovoltaic module is exposed to the air for a long time, and the dust falls on the surface of the photovoltaic module, blocking the light from entering, and reducing the light conversion efficiency of the photovoltaic module. It is urgent to deal with cleaning problems. This project intends to design a solar panel dust cleaning device that is mechanically cleaned by a brush and adsorbed by a chemical synthetic glue in the absence of water. To a large extent, it solves the problems caused by uncleaning, saves the use of water resources, and avoids the pollution of impurities brought by clean water washing.

Vibration characteristics of carbon-fiber reinforced composite drive shafts fabricated using filament winding technology

The metal connector and tube of the composite drive shaft were bonded together generally. However, the glued shafts showed numerous risks due to the instability of chemical glues. To avoid potential risks, filament winding with integrated flanges was proposed to prepare carbon fiber-reinforced composite (CFRP) drive shafts in this study. The natural frequency and damping of CFRP shafts were investigated by FEA and experiment. Results revealed that the natural frequency of CFRP shafts embedded in metal flanges is slightly lower than that of the glued CFRP shafts. The metal flanges did not affect the changing trend of the natural frequency with various fiber ply angles or thicknesses, and the damping had little effect on the natural frequency. The natural frequency of CFRP tubes and drive shafts was predicted using FEA and agreed well with the experimental results. The results of this study will be of great significance in the design and application of CFRP drive shafts.

Wideband Pyramidal Ridged Horn Design by SIW Technology

A wideband ridged horn using printed circuit and substrate integrated waveguide (SIW) technologies has been explored in this letter. A stepped flaring has been introduced in E-plane by adding multiple substrate layers, which is further loaded by a pair of E-plane flared balanced ridges to increase its operating bandwidth. The proposed technique is free from the requirement of any chemical glue or adhesive. A conventional SIW-based H-plane flaring is used. This horn is found to operate over 70% impedance bandwidth showing a consistent three-dimensional symmetric broadside radiation with an 8.7–19 dBi peak gain.

Bioinspired Adhesive Architectures: From Skin Patch to Integrated Bioelectronics.

The attachment phenomena of various hierarchical architectures found in nature have extensively drawn attention for developing highly biocompatible adhesive on skin or wet inner organs without any chemical glue. Structural adhesive systems have become important to address the issues of human-machine interactions by smart outer/inner organ-attachable devices for diagnosis and therapy. Here, advances in designs of biologically inspired adhesive architectures are reviewed in terms of distinct structural properties, attachment mechanisms to biosurfaces by physical interactions, and noteworthy fabrication methods. Recent demonstrations of bioinspired adhesive architectures as adhesive layers for medical applications from skin patches to multifunctional bioelectronics are presented. To conclude, current challenges and prospects on potential applications are also briefly discussed.

Resource-respectful construction – the case of the Urban Mining and Recycling unit (UMAR)

The growing elimination of resources calls for a paradigm shift from linear material consumption to circular economy - especially in the construction industry. The residential and research unit Urban Mining and Recycling (UMAR) in the modular experimental building NEST of Swiss research institute Empa consequently implements this claim: The design by Werner Sobek with Dirk E. Hebel and Felix Heisel is constructed from separable, ingrade material resources that are completely reusable, recyclable or compostable. The concept of cycles therefore plays a central role: Utilized materials are not consumed and then disposed of; instead, they are borrowed from their technical or biological cycle for a certain period of time and later returned to these material cycles. Considering its many reclaimed material resources, the apartment is a built example of urban mining. Designed for disassembly at the end of its service time, UMAR also represents a material depot for future projects: Instead of connecting elements and components irreversibly through wet connections such as chemical glues, UMAR uses screws, clamps or interlocking systems in order to recover all used substances ingrade and sorted. UMAR is both temporary material depot and material laboratory – while proving the claim that it is possible already today to build within a circular system.

Protonated g-C3N4/Ti3+ self-doped TiO2 nanocomposite films: Room-temperature preparation, hydrophilicity, and application for photocatalytic NOx removal

Fabrication of photocatalysis films with good adhesion, hydrophilicity, and high activity on substrates at room temperature is essential for their application in air pollution control. Herein, functionalized transparent composite films containing ultrathin protonated g-C3N4 (pCN) nanosheets and Ti3+ self-doped TiO2 nanoparticles (pCN/TiO2) were fabricated on glass at room temperature. Thickness of the films measures 80 nm with surface roughness of 7.16 nm. The adhesion ability was attributed to the viscosity of TiO2 sol, which served as “chemical glue” in the films. The high photo-induced hydrophilicity demonstrated their self-cleaning potential. pCN/TiO2 films showed remarkably high visible-light-driven activity in terms of NO removal in a continuous-flow mode. Photoelectrochemical tests demonstrated the superior charge separation efficiency of pCN/TiO2 films compared with that of pristine TiO2. As identified by electron spin resonance spectra, O2− and OH radicals were the key reactive species involved in NO removal. The possible mechanism for photocatalytic NO oxidation was proposed. Potential cytotoxicity of pCN/TiO2 films was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay to ensure the biosecurity. This work provides a facile route to fabricate nanocomposite films under ambient temperature. The nanocomposite films were characterized by photo-induced hydrophilicity, high NO removal efficiency, and good biocompatibility, showing its potential in large-scale application.

Polyaromatic molecular peanuts

Mimicking biological structures such as fruits and seeds using molecules and molecular assemblies is a great synthetic challenge. Here we report peanut-shaped nanostructures comprising two fullerene molecules fully surrounded by a dumbbell-like polyaromatic shell. The shell derives from a molecular double capsule composed of four W-shaped polyaromatic ligands and three metal ions. Mixing the double capsule with various fullerenes (that is, C60, C70 and Sc3N@C80) gives rise to the artificial peanuts with lengths of ∼3 nm in quantitative yields through the release of the single metal ion. The rational use of both metal–ligand coordination bonds and aromatic–aromatic π-stacking interactions as orthogonal chemical glue is essential for the facile preparation of the multicomponent, biomimetic nanoarchitectures.

Glueless Compound Ground Technique for Dielectric Resonator Antenna and Arrays

A newly conceived compound ground technique has been explored for dielectric resonator antenna (DRA) and arrays. The aim is to discard the traditional bonding by chemical glue that suffers from several limitations, especially in arrays. The proposed configuration uses a secondary ground plane with strategic perforations and clipping arrangement to achieve required mechanical stability along with accurate DRA positioning. It does not affect any radiation mode(s) or characteristics. The design has been tested for a single as well as a four-element array in S -band indicating close corroboration with its traditional counterpart. Scalability study ensures its operation up to K -band. This technique should find potential applications, especially in large arrays and in any platform subjected to mechanical vibrations.

Failure analysis of a large span longwall drift under water-rich roofs and its control techniques

Abstract In this study, failure analysis of a large span longwall drift under water-rich roofs was presented relying on field observations and numerical simulations. We had sought to find the key points that caused the drift roof collapse and water inrush. The numerical results were similar with that observed from field situations, and they both determined the origins of the roof failure problem. Wrong location selection and unreasonable excavation and support schemes were verified to be the most important factors that caused roof failure of the drift. Subsequently, a new excavation location with poor roof aquifer was recommended. A two staged excavation procedure was employed. Firstly, a small span roadway was excavated and reinforced, then the roadway was widened to the design width. After the first pass, boreholes were drilled to dewater the roof aquifer, and chemical glue material was grouted into the roof to cement the pre-existing discontinuities and induced fractures. Such control techniques had been undertaken in the new longwall drift. Both numerical modeling and field measurement verified that the proposed method could guarantee the large span drift stability during excavation and longwall preparation period. The interest of this study resides in combining the integrated methods to evaluate the state of failure in a highly detailed manner and determine simultaneously control techniques for the thorny problem under study.