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1.
Materials (Basel) ; 16(2)2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36676305

RESUMO

The use of carbon fibre reinforced polymer (CFRP) materials is increasing in many different industries, such as those operating in the aviation, marine, and automotive sectors. In these applications, composite parts are often joined with other composite or metallic parts, where adhesive bonding plays a key role. Unlike conventional joining methods, adhesive bonding does not add weight or require the drilling of holes, both of which are major sources of stress concentration. The performance of a composite joint is dependent on multiple factors and can be improved by modifying the adhesive layer or the composite layup of the adherend. Moreover, joint geometry, surface preparation, and the manufacturing methods used for production are also important factors. The present work reviews recent developments on the design and manufacture of adhesively bonded joints with composite substrates, with particular interest in adherend modification techniques. The effects of stacking sequence, use of thin-plies, composite metal laminates and its specific surface preparations, and the use of toughened surface layers in the composite adherends are described for adhesively bonded CFRP structures.

3.
Artigo em Inglês | MEDLINE | ID: mdl-36470291

RESUMO

BACKGROUND: Trifluridine-tipiracil plus bevacizumab has shown efficacy in previous phase 2 studies including patients with unresectable metastatic colorectal cancer. We aimed to investigate first-line trifluridine-tipiracil plus bevacizumab versus capecitabine plus bevacizumab in patients with unresectable metastatic colorectal cancer ineligible for intensive treatment. METHODS: In this open-label, randomised, phase 3 study, we enrolled patients aged 18 years and older with histologically confirmed metastatic colorectal cancer, ineligible for full-dose doublet or triplet chemotherapy and curative resection across 25 countries and regions. Participants were randomly allocated (1:1) to trifluridine-tipiracil plus bevacizumab or capecitabine plus bevacizumab until disease progression or unacceptable toxicity using an interactive web response system, stratified by Eastern Cooperative Oncology Group (ECOG) performance status (0 vs 1 vs 2), primary tumour location (right vs left colon), and the main reason for not being a candidate for intensive therapy (clinical condition vs non-clinical condition). The primary endpoint was investigator-assessed progression-free survival, defined as the time from randomisation to radiological progression or death from any cause, in the intention-to-treat population. Safety was assessed in all patients having taken at least one dose of the study drug. The trial is ongoing, findings presented here are those of the primary analysis of progression-free survival, conducted after 629 events had occurred. This study is registered with ClinicalTrials.gov, NCT03869892. FINDINGS: Between March 21, 2019, and Sept 14, 2020, 856 patients (54% male, 46% female) were randomly assigned to trifluridine-tipiracil plus bevacizumab (n=426) or capecitabine plus bevacizumab (n=430). After a median follow-up of 16·6 months (95% CI 16·5-17·1), the hazard ratio for progression-free survival for trifluridine-tipiracil plus bevacizumab versus capecitabine plus bevacizumab was 0·87 (0·75-1·02; p=0·0464; protocol-defined significance level of p=0·021 not met). Investigator-assessed median progression-free survival was 9·4 months (95% CI 9·1-10·9) with trifluridine-tipiracil plus bevacizumab versus 9·3 months (8·9-9·8) with capecitabine plus bevacizumab. The most common grade 3 and higher treatment-emergent adverse events were neutropenia (220 [52%] of 423 patients in the trifluridine-tipiracil plus bevacizumab group vs six [1%] of 427 in the capecitabine plus bevacizumab group), decreased neutrophil count (78 [18%] vs four [<1%]), anaemia (60 [14%] vs 16 [4%]), and hand-foot syndrome (none vs 61 [15%]). Nine deaths (five in the trifluridine-tipiracil plus bevacizumab group and four in the capecitabine plus bevacizumab group) were treatment related. INTERPRETATION: First-line trifluridine-tipiracil plus bevacizumab was not superior to capecitabine plus bevacizumab in this population. As expected, the safety profile differed between the two treatments, but there were no new safety concerns. Trifluridine-tipiracil plus bevacizumab represents a feasible alternative to capecitabine plus bevacizumab in this population. FUNDING: Servier International Research Institute, Suresnes, France.

4.
Materials (Basel) ; 15(23)2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36500037

RESUMO

The presence of residual stresses in composite materials can significantly affect material performance, especially when integrated in bonded joints. These stresses, often generated during the cure process, can cause cracking and distortion of the material, and are caused by differences in the coefficients of thermal expansion or cure shrinkage. In the current research, multimaterial adherends combining carbon-fibre-reinforced polymer (CFRP) and aluminium in a single-lap joint (SLJ) configuration are analysed, allowing us to understand the effect of the thermal residual stresses, developed during the curing process, in the overall performance of the joints. A numerical model resorting to a finite element analysis (FEA) is developed to assess and predict the behaviour of the joints. The use of FML (fibre metal laminates) was found to significantly improve the strength of the joints, as well as the failure mode. The proposed geometry performed similarly to the comparable FML geometry, in addition to a decrease in the joint weight.

5.
Materials (Basel) ; 15(24)2022 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-36556755

RESUMO

Due to their high elongation at failure and damping capacity, polyurethanes are one of the main types of adhesives used in automotive structures. However, despite the wide range of applications of adhesives, their fracture mechanics behavior is still poorly studied in the literature, especially when both the loading rate and ambient temperature change. Accordingly, the main aim of the current work is to deal with the research gap. In the current research, mode I fracture energy of a ductile polyurethane adhesive with adaptive properties for its industrial application is determined at different test speeds and temperatures. Tests were done at quasi-static, intermediate, and high-speed levels and each at three different temperatures, including low, high, and room temperature. Mode I fracture toughness was determined using DCB tests. Increasing the loading rate from quasi-static to 6000 mm/min was found to significantly increase the maximum strength of the tested DCBs (from 1770 N to about 4180 N). The greatest sensitivity to the loading rate was observed for the DCBs tested at room temperature, where the fracture energy increased by a factor of 3.5 from quasi-static (0.2 mm/min) to a high loading rate (6000 mm/min). The stiffness analysis of the DCB samples showed that the transition from below the Tg to room temperature decreases the bond stiffness by about 60%, while a further temperature increase (from 23 °C to 60 °C) has no significant effect on this parameter. Since polyurethane-bonded joints often experience a wide range of temperatures and loading rates in service, the obtained results can be used to design these joints more securely against such loading/environmental conditions.

6.
Viruses ; 14(11)2022 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-36366422

RESUMO

Although blood transfusion is an important therapeutic resource, transfusion-transmitted infections (TTIs) are still a cause for concern. Measures to mitigate this risk involve improvement of donor screening criteria and improvements in laboratory tests, especially the use of nucleic acid test (NAT). In this retrospective study we evaluated HIV, HTLV, HCV and HBV infection rates in blood donors of the Hematology and Hemotherapy Foundation of Bahia (Hemoba), Brazil, through serological and NAT results and the characteristics of donors. From February/2008 to December/2017, 777,446 blood donations were made. Most donors were male, aged 25-44 years, black and mixed race, and single or divorced. The density-type incidence (DTI; per 100,000) for each virus was 91.1 for HBV; 66.5 for HCV; 54.3 for HIV; and 33.9 for HTLV, with a decreasing trend observed over the period studied, except in the last biennium. NAT detected only 1 donor in immunological window for HIV (0.46/100,000 donations) and 3 donors in immunological window for HBV (1.8/100,000 donations). Serological positivity for all viruses studied was higher in the metropolitan region of Salvador, the state capital. Conclusion: DTI rates show a decreasing trend over the years studied, with a predominance of HBV infection. NAT allowed the detection of donors in immunological window periods, having an important role in improving transfusion safety.


Assuntos
Infecções por HIV , Hepatite B , Hepatite C , Feminino , Humanos , Masculino , Doadores de Sangue , Brasil/epidemiologia , Hepatite B/diagnóstico , Hepatite B/epidemiologia , Vírus da Hepatite B/genética , Hepatite C/diagnóstico , Hepatite C/epidemiologia , Infecções por HIV/diagnóstico , Infecções por HIV/epidemiologia , Estudos Retrospectivos , Adulto
7.
Eur J Dent ; 2022 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-36220114

RESUMO

OBJECTIVE: This study compared the shaping ability of the Hyflex CM and XP-endo Shaper rotary file systems in curved mesial canals of mandibular molars using micro-computed tomography. MATERIAL AND METHODS: Seventeen mesial roots of extracted first mandibular molars with two independent mesial canals were scanned before and after root canal preparation with the tested rotatory file systems. Each mesial canal from the same specimen was prepared with one of the two systems. The parameters analyzed were canal centering (transportation) for the cervical, middle, and apical segments, as well as for the entire canal (0-10 mm from the apex); and canal volume increase, canal surface area increase, and unprepared canal walls for two segments, 0 to 4 mm and 0 to 10 mm from the apex. RESULTS: There was no significant difference between both systems regarding canal centering (transportation), volume increase, and unprepared canal walls for the 0 to 10 mm segment (p> 0.05); however, a significant difference was observed for the 0 to 4 mm segment (p <0.01), where the Hyflex CM left 28.46% of unprepared walls and XP-endo Shaper left 13.26%. CONCLUSIONS: The shaping ability of the two tested rotatory file systems in mesial roots of first mandibular molars was similar for all parameters in all the segments evaluated, except for the 0 to 4 mm segment, where XP-endo Shaper left a smaller area of unprepared canal walls than Hyflex CM.

8.
Materials (Basel) ; 15(20)2022 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-36295230

RESUMO

The automotive industry, driven by the desire to decrease the environmental impact of vehicles, is permanently seeking to develop lightweight structural components, which lead to lower gas emissions and energy consumption, reducing their carbon footprint. In parallel, adopting innovative, constructive solutions, which dispense non-recyclable and energy-intensive materials, can increase the footprint reduction. Thus, an increase in the use of renewable materials for structural applications, including wood and its by-products, has been observed over the last few decades. Furthermore, composite materials are often joined by using petroleum-based synthetic adhesives, which should be progressively replaced by eco-friendly bio-adhesives. In this study, novel densified wood and wood/cork composites, joined with a bio-adhesive, are proposed and characterised. The densification of the wood aims to enhance the mechanical properties of the natural material, with the purpose of improving the energy absorption of the wood/bio-adhesive joint. To mitigate delamination and the brittle behaviour of wood/cork agglomerates were introduced between the wood substrate and the bio-adhesive. Different configurations of single lap joints (SLJ) were manufactured to study the effect of the overlap length and loading rate on the performance of the joints, both in terms of failure load and energy absorption. Afterward, the joints were numerically simulated. The densification process was successful, although it represents an additional challenge in terms of surface flatness, because the bio-adhesive requires zero bondline thickness. The increase of the overlap had a positive impact on the energy absorption of the joint, and the addition of cork resulted in a more consistent failure mode and higher strain to failure. The numerical models developed had a good correlation with the experimental results.

9.
Waste Manag ; 153: 99-109, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36067549

RESUMO

Chemical recycling can be used to separate fibers that are constituents of different types of fabrics. This type of process can be considered one of the most effective forms of recycling, given that a large part of fabrics is made up of fiber mixtures. As part of an innovative circular strategy, the main goal of this work was to study the conditions for extracting cellulose from mixed textile wastes by acid hydrolysis and further transform it into cellulose derivatives, thus contributing to reduce such wastes and expanding the possible sources of cellulose. Our work covers a wide range of textile wastes and addresses the main technical challenges of this recycling methodology. The percentage of recovered cellulose powder varies between 65 and 88%. To evaluate the feasibility of using the extracted cellulose as raw material to produce cellulose derivatives, two strategies were applied: etherification to obtain sodium carboxymethylcellulose (with degree of substituion between 0.27 and 0.61) and esterification, to obtain cellulose acetate (with degree of substituion of 2.59). The cellulose derivatives obtained are very useful as additives in the textile industry, and hence the concept and practice of a circular economy are promoted.


Assuntos
Carboximetilcelulose Sódica , Reciclagem , Celulose , Hidrólise , Pós , Têxteis
10.
J Colloid Interface Sci ; 626: 167-177, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-35785602

RESUMO

Transition metal dichalcogenides (TMDs), like other two-dimensional layered materials beyond graphene, have gained enormous interest in recent years owing to their distinct electronic and optical properties, and potential applicability in areas such as sensing, nanoelectronics and catalysis. Surfactant-assisted exfoliation is commonly used to prepare aqueous dispersions of TMD nanosheets, but a clear picture of the TMD and surfactant features that influence the dispersion process is still lacking. In this work, we present a systematic study of the dispersibility of MoS2, WS2 and MoSe2 in aqueous medium using a cationic (cetyltrimethylammonium bromide, CTAB) and an anionic (sodium cholate, SC) dispersant, in a wide concentration range (seven orders of magnitude) and resorting to a carefully controlled sonication-centrifugation procedure. We present detailed, high precision dispersibility curves (concentration of dispersed TMD versus concentration of surfactant used), together with zeta potential and pH measurements, allowing insight into the influence of the type of metal and chalcogen, surfactant charge and surfactant concentration, on the effectiveness of the exfoliation and stabilization. The metal (Mo vs. W) influences the dispersibility at low surfactant concentrations, while the chalcogen (S vs. Se) plays a more significant role as the surfactant concentration is increased, alongside the surfactant charge. Structural characterization by scanning electron microscopy (SEM), Raman spectroscopy and atomic force microscopy (AFM) shows that the methodology applied yields well-exfoliated nanosheets with controlled mean lateral dimension (≈ 100 nm) and thickness (≤5 layers). Finally, the type of ionic surfactant (cationic vs. anionic) and its concentration play a pivotal role in the profile of the dispersibility curves, leading us to propose two types of master curves with distinct regions of phase behavior.

11.
Materials (Basel) ; 15(11)2022 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-35683116

RESUMO

Adhesives are extensively used in the automotive and aeronautical industries as they enable the creation of durable and light weight joints, with exceptional strength to weight ratios. The constant search for the means of adapting the mechanical performance of adhesives to each application has led to the use of several types of fillers to change their properties. Following a study on the effect of inorganic fillers, i.e., hollow glass beads, in the failure mechanisms of single lap joint's (SLJ), this work focuses on the response of the strength and fracture properties of structural adhesives to this filler. To this end, their tensile strength and mode I fracture properties were thoroughly analyzed by performing bulk tensile and double-cantilever beam (DCB) tests, at a quasi-static speed. The specimens were manufactured by adding different %v/v of filler to two epoxy-based crash resistant adhesives. Both adhesives have shown a negligible effect on the tensile strength, a decrease in strain at failure and critical energy release rate in mode I, as well as an increase of the Young's modulus, for higher % in volume of hollow glass beads. These phenomena were further analyzed recurring to scanning electron microscopy, and the concept of rule of mixtures.

12.
Environ Sci Pollut Res Int ; 29(50): 76177-76191, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35668261

RESUMO

This study evaluated carbon dynamics in a carbonate microbasin (Bule stream), located in an important metallogenetic area (QF) in Brazil. River water collections were performed on a base and high flow. The microbasin showed high DIC, with HCO3- being the main component, followed by CO2. The pCO2 showed high values, indicating fluxes in the water → air direction. The degassing was 683.4 mmol m-2 day-1 (average at low flow) and 43.4 mmol m-2 day-1 (average at high flow). The fluvial flow was 9 to 31 kg km-2 day-1 of HCO3- and 1.4 to 0.7 kg km-2 day-1 of CO2, respectively, at the base and high flow. Considering the importance of the lithological unit of the Minas Supergroup for the QF, the total flow of CO2 released by all the basins that compose such units was estimated. The estimated values were 1.3 × 1012 mmol day-1 in low flow and 8.4 × 1010 mmol day-1 in high flow. The data obtained in this study were the first in the QF region. The Bule stream is an environmental protection area, free from contamination, considered a background for other drainage basins inserted in the QF. The results obtained reinforce the importance of hydrographic microbasins influence on the river carbon fluxes in a regional and global context.


Assuntos
Dióxido de Carbono , Rios , Brasil , Carbono/análise , Dióxido de Carbono/análise , Carbonatos , Dacarbazina , Água
13.
Adv Colloid Interface Sci ; 304: 102667, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35462268

RESUMO

The development of functional materials with uniquely advanced properties lies at the core of nanoscience and nanotechnology. From the myriad possible combinations of organic and/or inorganic blocks, hybrids combining metal nanoclusters and carbon nanomaterials have emerged as highly attractive colloidal materials for imaging, sensing (optical and electrochemical) and catalysis, among other applications. While the metal nanoclusters provide extraordinary luminescent and electronic properties, the carbon nanomaterials (of zero, one or two dimensions) convey versatility, as well as unique interfacial, electronic, thermal, optical, and mechanical properties, which altogether can be put to use for the desired application. Herein, we present an overview of the field, for experts and non-experts, encompassing the basic properties of the building blocks, a systematic view of the chemical preparation routes and physicochemical properties of the hybrids, and a critical analysis of their ongoing and emerging applications. Challenges and opportunities, including directions towards green chemistry approaches, are also discussed.


Assuntos
Carbono , Nanoestruturas , Carbono/química , Catálise , Metais/química , Nanoestruturas/química , Nanotecnologia
14.
Environ Sci Pollut Res Int ; 29(28): 42929-42946, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35091934

RESUMO

The Três Marias Reservoir is the ninth largest reservoir in Brazil, becoming crucial for national strategic development. However, many anthropic activities may affect the sediment quality, promoting the need for a proper environmental assessment. This research appraised the seasonal influences on the Três Marias Reservoir's sediment geochemistry, elucidating possible anthropogenic impacts. The concentrations of Mg, Al, Ca, Cr, Fe, Co, Cu, Cd, Ti, Mn, Ni, Zn, Ba, and Pb were measured in 78 samples of bottom sediments regarding the two seasons of the area, a dry winter and rainy summer. The median ± 2 median absolute deviation (MAD) settled the geochemical background and environmental thresholds for the two seasons. The sediment quality guidelines CONAMA 344/12 highlight the possible adverse ecological effects of pollutants. The hierarchical clustering analysis, the geoaccumulation index, and the pollution load index delineated the polluted zones. The pollution load index ranges from 0.25 to 2.28 in the dry season and 0.56 to 2.11 in the rainy season, defining three affected zones in the reservoir. Forestry and agriculture are the probable pollution sources, reaching warning levels that should be considered in further environmental strategies.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Brasil , Monitoramento Ambiental , Sedimentos Geológicos/análise , Metais Pesados/análise , Rios , Estações do Ano , Poluentes Químicos da Água/análise
15.
Eur J Dent ; 16(1): 230-233, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34674195

RESUMO

Cavernous hemangiomas are benign malformations of vascular origin, usually well circumscribed and slow to grow. These lesions can be asymptomatic, being discovered unintentionally in imaging exams or symptomatic, indicated mainly by the presence of proptosis, diplopia, and visual disturbances by optic nerve compression. The complementary exams involve computed tomography associated with contrast, color Doppler, magnetic resonance, and angiography. Treatment can be conservative or surgical depending on the case, and the open therapy usually involves lateral, supraorbital, transconjunctival, transantral, pterional, transnasal, and extradural endoscopic orbitotomy. The present study aimed to report a recurrent case of hemangioma in the orbital cavity signaled by ocular proptosis, hyperemia, and ocular pain.The lesion was achieved through the Weber-Ferguson access with zygomatic osteotomy and preservation of the infraorbital nerve. The excision of the lesion was performed, and the previously displaced fragments were fixed with 1.5 mm mini plates. The patient has a chance of progressing with visual impairment due to considerable manipulation of the optic nerve and is being followed up.The reported case showed a successful diagnosis and therapeutic conduct, remaining now in the evolution and follow-up scenario.

16.
ChemMedChem ; 17(5): e202100650, 2022 03 04.
Artigo em Inglês | MEDLINE | ID: mdl-34882979

RESUMO

Inspired by previous disclosure of room-temperature ionic liquids derived from primaquine and cinnamic acids, which displayed slightly enhanced blood-stage activity compared to the parent drug, we have now combined this emblematic antimalarial with natural fatty acids. This affords surface-active ionic liquids whose liver-stage antiplasmodial activity is either retained or slightly enhanced, while revealing blood-stage antiplasmodial activity at least one order of magnitude higher than that of the parent compound. These findings open new perspectives towards the cost-effective recycling of classical drugs that are either shelved or in decline, and which is not limited to antimalarial agents.


Assuntos
Antimaláricos , Antagonistas do Ácido Fólico , Líquidos Iônicos , Antimaláricos/farmacologia , Análise Custo-Benefício , Antagonistas do Ácido Fólico/farmacologia , Líquidos Iônicos/farmacologia , Plasmodium falciparum , Primaquina/farmacologia
17.
Artigo em Inglês | MEDLINE | ID: mdl-36653241

RESUMO

BACKGROUND: The BRAF inhibitor encorafenib in combination with cetuximab was recently approved for patients with BRAFV600E-mutated (BRAFV600Emut) metastatic colorectal cancer (mCRC). Approval was based on positive results from the phase 3 BEACON CRC study in BRAFV600Emut mCRC patients who had progressed after 1-2 previous regimens. This analysis provides a detailed examination of the adverse events (AEs) of interest (AEIs) with encorafenib+cetuximab in the BEACON study to aid gastrointestinal oncologists, given the limited experience with this combination. MATERIALS AND METHODS: AEIs, including dermatological AEs, arthralgia/myalgia, nausea/vomiting, diarrhea, abdominal pain, fatigue/asthenia and nephrotoxicity, were examined in the doublet therapy group. Clinical characteristics associated with these AEs, AE grade, time to onset and time to resolution were also studied. RESULTS: Safety analysis included 216/220 patients randomized to doublet therapy. The most commonly occurring AEI was dermatological toxicity (75.5%), followed by arthralgia/myalgia (56.0%) and fatigue/asthenia (56.0%). Other than nephrotoxicity (7 patients; 5/7 with Grade 3 or 4), most AEs were Grade 1 or 2. Most AEs were more common in women than men (nausea/vomiting, diarrhea, abdominal pain, dermatological AEs, and arthralgia/myalgia). Nausea/vomiting, abdominal pain and fatigue/asthenia were more common in patients aged ≥70 years. Most AEs developed early, within the first 1-2 months of treatment, and resolved within 1-2 weeks. In addition, survival outcomes were better in patients experiencing arthralgia/myalgia or dermatological toxicities. CONCLUSION: This analysis indicated that, except for rare cases of nephrotoxicity, encorafenib+cetuximab is well tolerated in most patients, with most AEIs being mild-to-moderate in severity, occurring early and resolving rapidly. CLINICAL TRIAL REGISTRATION: the BEACON study (ClinicalTrials.gov, NCT02928224; EudraCT, 2015-005805-35).

18.
Polymers (Basel) ; 15(1)2022 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-36616439

RESUMO

Over recent decades, the need to comply with environmental standards has become a concern in many industrial sectors. As a result, manufacturers have increased their use of eco-friendly, recycled, recyclable, and, overall, more sustainable materials and industrial techniques. One technique highly dependent on petroleum-based products, and at the edge of a paradigm change, is adhesive bonding. Adhesive bonding is often used to join composite materials and depends upon an adhesive to achieve the connection. However, the matrices of the composite materials and the adhesives used, as well as, in some cases, the composite fibres, are manufactured from petrochemical products. Efforts to use natural composites and adhesives are therefore ongoing. One composite that has proven to be promising is wood due to its high strength and stiffness (particularly when it is densified), formability, and durability. However, wood must be very carefully characterised since its properties can be variable, depending on the slope of the grains, irregularities (such as knots, shakes, or splits), and on the location and climate of each individual tree. Therefore, in addition to neat wood, wood composites may also be a promising option to increase sustainability, with more predictable properties. To bond wood or wooden composite substrates, bio-adhesives can be considered. These adhesives are now formulated with increasingly enhanced mechanical properties and are becoming promising alternatives at the structural application level. In this paper, wooden adhesive joints are surveyed considering bio-adhesives and wood-based substrates, taking into consideration the recent approaches to improve these base materials, accurately characterise them, and implement them in adhesive joints.

19.
Materials (Basel) ; 14(22)2021 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-34832412

RESUMO

The use of modern structural adhesives provides a lightweight, practical, and high strength joining methodology, which is increasingly being adopted in the automotive and aeronautical sectors, among many others. However, the strict mechanical performance standards that must be met in these applications require a constant search for ways of improving the adhesives' behavior, which has led to the growing use of reinforcements as a way of improving the capabilities of bonded joints. The aim of this work was, thus, to analyze how the addition of inorganic fillers to the adhesive layer affects a joint's strength and its failure mechanism. To this end, single lap joint specimens with mild steel and high strength steel substrates were tested, at quasi-static speeds, and with different amounts of glass microspheres reinforcing two different structural adhesives. The experimental results indicated that the addition of glass particles reduced the joint performance for both substrates under study. Furthermore, the failure pattern was found to evolve from adhesive failure to a cohesive type of failure as the amount of glass particles present in the adhesive was increased.

20.
Environ Res ; 202: 111756, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34329632

RESUMO

Groundwater consumption has become increasingly relevant for urban development. The city of Montes Claros (Minas Gerais, Brazil) is located in the border region of the Brazilian semi-arid polygon and has registered conflicts of water use for decades ago. The study area contains a complex karst system responsible for the heterogeneous permeability of water recharge and groundwater flow. The urban area of Montes Claros is located in the Vieira River watershed and contains different groundwater wells used to agro-industrial and human consumption. Almost groundwater captions have a low specific capacity with a consequent groundwater depletion. On the region, there are significant areas with a negative water balance concerning to water recharge and groundwater exploitation. Groundwater flow has a regional dominant direction of SW-NE, however locally, groundwater flow varies and could be identified some clusters with high hydrological potential. The contrast between hydrogeological features of the outcropping lithotypes added to the geological structures contribute to variations in the potentiometric level and in the productivity of aquifers. The main aim of this study is a reviewer of the regional hydrogeology of the municipality of Montes Claros to evaluate a potential groundwater availability on the urban area and minimize a groundwater overexploitation and scarcity. A detailed characterization of the local hydrogeology from Montes Claros region will be crucial to a definition of more efficient water supply policies on the management of water resources, particularly in a scenario of climate change and water scarcity in semi-arid areas.


Assuntos
Água Subterrânea , Água , Brasil , Monitoramento Ambiental , Humanos , Hidrologia
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