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1.
Microsurgery ; 44(1): e31101, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37614190

RESUMO

The reinnervated gracilis muscle free flap represents a workhorse of facial reanimation. This procedure is carried out secondarily to parotid resections, due to advanced tumors that spread to the surrounding structures. Finding recipient vessels might be problematic if other reconstructive procedures are needed to address the defects. This paper describes a procedure to inset a reinnervated gracilis muscle free flap in a vessel depleted patient, through intraoral anastomoses to avoid venous interposition grafts. A 52-year-old man developed an advanced adenocarcinoma of the deep parotid lobe and underwent radical surgical excision including the mandibular ramus, condyle, and facial soft tissues (defect size: 8 cm × 4 cm). A secondary double-flap reconstruction restored the mandibular defect and inset a cross-face nerve graft. A third intervention finalized the facial reanimation with a 10 cm reinnervated gracilis muscle free flap. The gracilis flap inset was inverted resulting in the proximal flap (pedicle side) lying on the buccal aspect. This allowed vessel joining from the contralateral side via intraoral anastomoses. No complications occurred within and after the intervention. However, the adenocarcinoma relapsed before reinnervation of the gracilis. The patient also had distant brain and lung metastases and received best supportive care. The inverted gracilis muscle free flap may represent an option for attaining facial reanimation in vessel-depleted patients avoiding long interposition venous grafts.


Assuntos
Adenocarcinoma , Paralisia Facial , Retalhos de Tecido Biológico , Músculo Grácil , Procedimentos de Cirurgia Plástica , Masculino , Humanos , Pessoa de Meia-Idade , Retalhos de Tecido Biológico/irrigação sanguínea , Paralisia Facial/cirurgia , Paralisia Facial/etiologia , Músculo Grácil/transplante , Adenocarcinoma/cirurgia
3.
Biomedicines ; 11(8)2023 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-37626803

RESUMO

Chewing improves visuospatial performance through locus coeruleus (LC) activation. The effects of bilateral and unilateral mastication were investigated in subjects showing different degrees of asymmetry in masseter electromyographic (EMG) activity during clenching and in pupil size at rest (anisocoria), which is a proxy of LC imbalance. Correlations between performance changes and asymmetry values were found in males, but not in females. Among males, subjects with low asymmetry values (balanced-BAL) were more sensitive than those with high asymmetry values (imbalanced-IMB) to bilateral and unilateral chewing on the side with higher EMG activity (hypertonic). The opposite was true for hypotonic side chewing. BAL subjects were sensitive to unilateral chewing on both sides, while in IMB subjects, hypertonic side chewing did not influence performance in either males or females. Bilateral chewing elicited larger effects in BAL subjects than in IMB subjects, exceeding the values predicted from unilateral chewing in both groups. Finally, pupil size and anisocoria changes elicited by chewing were correlated with asymmetry values, independent of sex. Data confirmed the facilitation of visuospatial performance exerted by chewing. Trigeminal asymmetries modulate the chewing effects, making occlusal rebalancing an appropriate strategy to improve performance.

4.
Diagnostics (Basel) ; 13(13)2023 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-37443531

RESUMO

(1) Background: Medication-related osteonecrosis of the jaws (MRONJ) is an adverse drug reaction characterized by progressive bone disruption and necrosis in the mandibular and/or maxillary bones. It occurs in individuals who have received antiresorptive drugs without prior radiotherapy. Since its first reported cases in the USA in 2003, extensive literature has emerged worldwide, leading to significant advancements in understanding MRONJ's pathogenesis and management. (2) Results: This article aims to compare the current national recommendations provided by the Italian Society of Maxillofacial Surgery (SICMF)/Italian Society of Oral Pathology and Medicine (SIPMO) and the American Association of Oral and Maxillofacial Surgeons (AAOMS). (3) Conclusions: Historically, the AAOMS advocated for a more conservative approach compared to the Italian guidelines. However, in their 2022 update, the AAOMS adopted a different perspective based on reported evidence, highlighting the advantages of early surgical treatment. Despite resolving some initial controversies, differences still exist between the two sets of recommendations, particularly regarding diagnosis and staging.

5.
PLoS One ; 18(6): e0287123, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37307276

RESUMO

The effects of postural training on postural stability and vestibulospinal reflexes (VSRs) were investigated in normal subjects. A period (23 minutes) of repeated episodes (n = 10, 50 seconds) of unipedal stance elicited a progressive reduction of the area covered by centre of pressure (CoP) displacement, of average CoP displacement along the X and Y axes and of CoP velocity observed in this challenging postural task. All these changes were correlated to each other with the only exception of those in X and Y CoP displacement. Moreover, they were larger in the subjects showing higher initial instability in unipedal stance, suggesting that they were triggered by the modulation of sensory afferents signalling body sway. No changes in bipedal stance occurred soon and 1 hour after this period of postural training, while a reduction of CoP displacement was apparent after 24 hours, possibly due to a beneficial effect of overnight sleep on postural learning. The same period of postural training also reduced the CoP displacement elicited by electrical vestibular stimulation (EVS) along the X axis up to 24 hours following the training end. No significant changes in postural parameters of bipedal stance and VSRs could be observed in control experiments where subjects were tested at identical time points without performing the postural training. Therefore, postural training led to a stricter control of CoP displacement, possibly acting through the cerebellum by enhancing feedforward mechanisms of postural stability and by depressing the VSR, the most important reflex mechanism involved in balance maintenance under challenging conditions.


Assuntos
Terapia de Aceitação e Compromisso , Reflexo , Humanos , Aprendizagem , Cerebelo , Grupos Controle
6.
Microsurgery ; 43(3): 281-285, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36709414

RESUMO

Extended maxillectomies with orbital exenteration and facial soft tissue resection need careful planning to achieve satisfactory functional and esthetic outcomes. Only a few solutions provide enough hard and soft tissue on a single pedicle, and only some reconstructive goals might be achievable with a single flap. This paper describes an original inset of the gracilis muscle free flap, used in a vessels depleted patient to salvage a partially failed multi-flap reconstruction after an extensive maxillectomy. A 55-years old man underwent a surgical intervention for a fibrosarcoma of the right maxilla. Due to the disease extension, the resection included right maxilla and palate, the overlying facial soft tissues (including the paranasal, cheek, and infraorbital regions), and the entire orbital content (orbital exenteration). A double flap reconstruction-a free fibula flap and a deep circumflex iliac artery flap-was carried out primarily. However, an intraoperative complication caused a partial flap loss, resulting in a complex tridimensional defect of the orbit and the oral cavity. Therefore, a 18 cm long gracilis muscle free flap was used to fill the defect and save the remaining bony reconstruction. The muscle was inset behind the transplanted bone to seal both the orbit and the oral cavity. No complications occurred after the salvage surgery, with a stable result at the 6-months follow-up. The designed gracilis muscle free flap proved a reliable option for this salvage surgery. However, it could be helpful also in the primary reconstruction of extended maxillectomies in combination with another composite free flap.


Assuntos
Retalhos de Tecido Biológico , Procedimentos de Cirurgia Plástica , Masculino , Humanos , Pessoa de Meia-Idade , Fíbula/cirurgia , Maxila/cirurgia , Retalhos de Tecido Biológico/cirurgia , Órbita/cirurgia
7.
Cancers (Basel) ; 13(17)2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34503208

RESUMO

BACKGROUND: health-related quality of life (HRQOL) represents a secondary endpoint of medical interventions in oncological patients. Our aim was to highlight potential sources of bias that could be encountered when evaluating HRQOL in oral cancer patients. METHODS: this review followed PRISMA-ScR recommendations. PARTICIPANTS: patients treated for oral cancer. CONCEPT: HRQOL assessed by EORTC QLQ-C30 and QLQ-H&N35/QLQ-H&N43. A critical appraisal of included studies was performed to evaluate the accuracy of data stratification with respect to HRQOL determinants. RESULTS: overall, 30 studies met the inclusion criteria, totaling 1833 patients. In total, 8 sociodemographic (SDG) and 15 disease/treatment-specific (DT) HRQOL determinants (independent variables) were identified. The mean number of the independent variables was 6.1 (SD, 4.3)-5.0 (SD, 4.0) DT-related and 1.1 (SD, 1.8) SDG-related variables per article. None of the included papers considered all the identified determinants simultaneously. CONCLUSIONS: a substantial lack of evidence regarding HRQOL determinants was demonstrated. This strongly weakens the reliability of the reported findings due to the challenging presence of baseline confounding, selection, and omitted variable biases. The proposed approach recommends the use of further evaluation tools that gather more variables in a single score together with a selection of more homogeneous, reproducible, and comparable cohorts based on the identified baseline confounding.

8.
Sci Rep ; 11(1): 4744, 2021 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-33637775

RESUMO

Trigeminal input exerts acute and chronic effects on the brain, modulating cognitive functions. Here, new data from humans and animals suggest that these effects are caused by trigeminal influences on the Locus Coeruleus (LC). In humans subjects clenching with masseter asymmetric activity, occlusal correction improved cognition, alongside with reductions in pupil size and anisocoria, proxies of LC activity and asymmetry, respectively. Notably, reductions in pupil size at rest on the hypertonic side predicted cognitive improvements. In adult rats, a distal unilateral section of the trigeminal mandibular branch reduced, on the contralateral side, the expression of c-Fos (brainstem) and BDNF (brainstem, hippocampus, frontal cortex). This counterintuitive finding can be explained by the following model: teeth contact perception loss on the lesioned side results in an increased occlusal effort, which enhances afferent inputs from muscle spindles and posterior periodontal receptors, spared by the distal lesion. Such effort leads to a reduced engagement of the intact side, with a corresponding reduction in the afferent inputs to the LC and in c-Fos and BDNF gene expression. In conclusion, acute effects of malocclusion on performance seem mediated by the LC, which could also contribute to the chronic trophic dysfunction induced by loss of trigeminal input.


Assuntos
Anisocoria , Disfunção Cognitiva , Nervo Trigêmeo/fisiologia , Adulto , Animais , Estimulação Elétrica , Eletromiografia , Feminino , Humanos , Locus Cerúleo/fisiologia , Masculino , Má Oclusão , Músculo Masseter/fisiologia , Pessoa de Meia-Idade , Contração Muscular/fisiologia , Midríase , Ratos Wistar
9.
Front Syst Neurosci ; 15: 749444, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35002642

RESUMO

Chewing improves cognitive performance, which is impaired in subjects showing an asymmetry in electromyographic (EMG) masseter activity during clenching. In these subjects, the simultaneous presence of an asymmetry in pupil size (anisocoria) at rest indicates an imbalance in Ascending Reticular Activating System (ARAS) influencing arousal and pupil size. The aim of the present study was to verify whether a trigeminal EMG asymmetry may bias the stimulating effect of chewing on cognition. Cognitive performance and pupil size at rest were recorded before and after 1 min of unilateral chewing in 20 subjects with anisocoria, showing an EMG asymmetry during clenching. Unilateral chewing stimulated performance mainly when it occurred on the side of lower EMG activity (and smaller pupil size). Following chewing on the hypotonic side, changes in cognitive performance were negatively and positively correlated with those in anisocoria and pupil size, respectively. We propose that, following chewing on the hypotonic side, the arousing effects of trigeminal stimulation on performance are enhanced by a rebalancing of ARAS structures. At variance, following chewing on the hypertonic side, the arousing effect of trigeminal stimulation could be partially or completely prevented by the simultaneous increase in ARAS imbalance.

10.
Expert Rev Anticancer Ther ; 21(1): 9-22, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33081545

RESUMO

INTRODUCTION: The management of squamous cell carcinoma (SCC) of the tongue represents the most demanding treatment planning in head and neck surgery. Ablation followed by free flap reconstruction is considered the gold standard, but not all patients are suitable for this strategy. The aim of this review is to provide a comprehensive view of surgical reconstruction possibilities in patients not eligible for free flaps. METHODS: Following PRISMA recommendations, a systematic literature review was conducted searching for original papers that investigated outcomes of patients treated by surgical ablation for tongue SCC followed by reconstruction with local or pedicled flaps. Selected papers were read and data extracted for qualitative analysis. RESULTS: Twenty articles met the inclusion/exclusion criteria. The study design was case series in sixteen papers, cohort study in the remaining four. Four different local flaps (BMM, FAMM, NLIF, SMIF) and four regional flaps have been discussed in included studies (IHF, SFIF, SCM, PMMC). CONCLUSION: The improved anatomical knowledge makes local flaps a reliable alternative to free tissue transfer in cases requiring small-/medium-sized defects. Regional flaps still represent cornerstones in reconstruction of the tongue. Ease of execution, costs-to-benefit ratio, low-rate complications, minimal donor site morbidity represent the best advantages choosing local/regional flaps.


Assuntos
Neoplasias de Cabeça e Pescoço/cirurgia , Carcinoma de Células Escamosas de Cabeça e Pescoço/cirurgia , Neoplasias da Língua/cirurgia , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Procedimentos de Cirurgia Plástica/métodos , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Retalhos Cirúrgicos , Neoplasias da Língua/patologia
11.
Brain Res ; 1751: 147194, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33159973

RESUMO

It has been observed that, in patients affected by temporomandibular disorders (TMDs) and edentulism, a left-right asymmetry in electromyographic (EMG) activity of masseter muscles during clenching and in pupil size at rest (anisocoria) is present. Both are greatly reduced by an orthotic-prosthetic correction. In parallel, the correction significantly improves cognitive performance. These effects are possibly due to the recovery of a cortical balance, via Locus Coeruleus (LC) modulation, whose activity is powerfully affected by the sensorimotor trigeminal input. The role of this functional axis was further investigated in subjects without overt occlusal or dental problems. In these individuals, the EMG asymmetry was significantly correlated to anisocoria at rest, with the dental arches open or in contact. Also in normal subjects, both the EMG and the pupil asymmetry during clenching could be significantly reduced by an orthotic (bite) correction. Closing the arches without bite increased anisocoria and reduced performance in the Spinnler-Tognoni matrices test, as well as the mydriasis induced by a haptic task. When the bite was interposed, anisocoria was reduced, while both performance and task-related mydriasis were enhanced. Since pupil size is considered a proxy of the LC activity, these results suggest that asymmetric occlusion biases the LC discharge and the hemispheric excitability, possibly via a sensorimotor trigeminal imbalance. Removing the anisocoria through bite correction re-establishes a symmetric LC discharge, improving performance and enhancing task-related mydriasis. Therefore, occlusal balancing may represent a tool for improving subjective performance and may be exploited for training and rehabilitative purposes.


Assuntos
Anisocoria/patologia , Cognição/fisiologia , Transtornos da Articulação Temporomandibular/fisiopatologia , Adulto , Encéfalo/fisiologia , Eletromiografia , Feminino , Humanos , Arcada Parcialmente Edêntula/fisiopatologia , Locus Cerúleo/fisiologia , Masculino , Mandíbula/fisiologia , Músculo Masseter/fisiologia , Pessoa de Meia-Idade , Contração Muscular/fisiologia , Pupila/fisiologia , Transtornos da Articulação Temporomandibular/metabolismo
12.
Cancer Rep (Hoboken) ; 4(2): e1315, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33295154

RESUMO

BACKGROUND: Primary branchiogenic carcinoma (PBC) is an extremely rare and poorly documented disease developed from a brachial cleft cyst. CASE: A 51-year-old patient was referred to our unit for an upper neck mass. PBC was confirmed in accordance with Kahfif's diagnostic criteria. Prophylactic selective neck dissection was performed in a second-stage surgery to ensure the complete removal of the neoplasm. Branchiogenic origin with lymphoid tissue was confirmed in the "host cyst" after histological examination and no other tumors were found elsewhere. Regular follow up documented no relapse 12 months after surgery. CONCLUSIONS: Although rare, PBC must be suspected in presence of cervical masses, especially in patients older than 40 years. A standardized treatment algorithm still lacks, but prophylactic selective neck dissection could be considered as the first line choice after the diagnosis has been confirmed.


Assuntos
Branquioma/diagnóstico , Neoplasias de Cabeça e Pescoço/diagnóstico , Carcinoma de Células Escamosas de Cabeça e Pescoço/diagnóstico , Branquioma/patologia , Branquioma/cirurgia , Neoplasias de Cabeça e Pescoço/patologia , Neoplasias de Cabeça e Pescoço/cirurgia , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Esvaziamento Cervical , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/cirurgia , Resultado do Tratamento
13.
Case Rep Surg ; 2020: 8890935, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33145117

RESUMO

Introduction. Orofacial reconstruction plays an important role in the treatment of patients affected by oral and maxillofacial cancers. Improvements in technologies and studies of biomaterials have widely expanded surgical possibilities to achieve good functional and aesthetic outcomes. By the way, xenografting procedures gained great consensus in the last decades, because of their documented reliability and efficacy. We present a case of anterior maxillary chondrosarcoma (CHS) that has undergone surgical ablation followed by reconstruction with an equine-derived bone xenograft. Case Presentation. A 68-year-old woman affected by CHS of the premaxilla underwent surgical ablation involving the four incisors followed by reconstruction using an equine-derived bone substitute. Bony reconstruction was planned to achieve implant and dental prosthetic rehabilitation at a second surgical time. Primary surgery was carried out without complications. Good integration of the graft was confirmed by radiological examination. At 12-month follow-up, the patient refused the implant placement and spontaneously adopted a mobile prosthesis. One year later, plates and screws were removed, because of the exposure of a titanium plate. The graft was finally rejected within 3 weeks. Discussion. Nonantigenic equine-derived biomaterials have shown reliability and a good safety profile. In the presented case, implant insertion should have been performed 12 months after the primary surgery. During the follow-up, until dental mobile prosthesis was applied, clinical and instrumental examinations demonstrated a good integration of the graft. We suppose that a chronic inflammation of the mucosa led to the exposure of the plate, perhaps due to pressure, minimal movements, or imperfect fitting of the mobile prosthesis. Removal of fixation means was performed to prevent grafting failure, without success. On the other hand, missing load could induce the graft to act just like a prosthesis, without a real process of integration. Safety and reliability of equine-derived bone xenografts cannot be currently confirmed if not followed by implant insertion and dental rehabilitation.

14.
J Craniofac Surg ; 31(6): e604-e606, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32657979

RESUMO

One of the most attractive areas of the face are the lips, they are crucial for emotion and communication, both during animation and at rest. Throughout the years, several techniques to obtain permanent lip enhancement have been introduced, such as the use of nonresorbable fillers. The main problem related to permanent fillers is that undesirable results could not always be repaired; although lip sequelae can be addressed surgically, some surgeons will not perform this type of procedure due to its complexity and the lack of guidelines.In this paper, the authors present a case of a labial incompetence developed after lips implant removal performed elsewhere; after clinical examination the patient was planned for surgery, although during preoperative instrumental examination (chest X-ray) a solitary pulmonary nodule was noted; further investigation performed with needle biopsy revealed a lung cancer. For this reason, the surgical procedure planned for lip restoration was not performed; however, the patient asked for a minimally invasive procedure, thus to improve, although temporarily, her lips appearance.For the aforementioned reasons, the patient was treated just with hyaluronic acid injections achieving a pleasant result, solving also the labial incompetence at rest.To the best of the author's knowledge, this paper represents the first one describing the use of hyaluronic acid injections to restore lip competence following surgical removal of permanent implant.


Assuntos
Ácido Hialurônico/administração & dosagem , Lábio , Técnicas Cosméticas/efeitos adversos , Implantes Dentários , Feminino , Humanos , Injeções , Lábio/cirurgia , Pessoa de Meia-Idade
15.
J Oral Maxillofac Surg ; 78(6): 973-978, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32171599

RESUMO

PURPOSE: We evaluated the outcomes and differences in surgical time and hospitalization length for patients with an isolated zygomatic arch (ZA) fracture treated by percutaneous wire reduction with external fixation. PATIENTS AND METHODS: We designed and developed a retrospective study of patients with isolated ZA fractures treated from 2014 to 2019. The predictor variable was the operative treatment, represented by percutaneous reduction with external fixation. The primary outcome variables were the surgical time and hospitalization length. Other variables, including functional and esthetic results (evaluated by clinical and radiologic assessments) and the rate of immediate and delayed complications during a 6-month minimum follow-up period, were considered. Descriptive statistics were computed and compared with the international reported data. RESULTS: A total of 15 patients met specific inclusion and exclusion criteria. The 15 fractures were grouped using the classification reported by Kim et al as type 1A (n = 9) and type 1B (n = 6). No significant differences were found between the 2 groups, except for the fracture type. The operative treatment was performed with the patient under general anesthesia (n = 12) or local anesthesia with sedation (n = 3). Only 1 patient developed a complication (early hematoma). No other cases of early or delayed complications were reported. Two patients required a traditional surgical operation with the Gilles approach. The average hospitalization length and surgical time were 0.8 night and 18.4 minutes for the type 1A group and 0.7 night and 19.0 minutes for the type 1B group, respectively. Optimal esthetic and functional outcomes were obtained for all 15 patients. CONCLUSIONS: The results of the present study suggest that optimal esthetic and functional results can be obtained, minimizing the effect on soft tissues and patient discomfort, with a short surgical time and low rate of complications.


Assuntos
Fraturas Cranianas , Fraturas Zigomáticas , Estética Dentária , Fixação de Fratura , Fixação Interna de Fraturas , Humanos , Estudos Retrospectivos , Resultado do Tratamento , Zigoma
16.
J Vis Exp ; (153)2019 11 26.
Artigo em Inglês | MEDLINE | ID: mdl-31840660

RESUMO

Current scientific literature provides evidence that trigeminal sensorimotor activity associated with chewing may affect arousal, attention, and cognitive performance. These effects may be due to widespread connections of the trigeminal system to the ascending reticular activating system (ARAS), to which noradrenergic neurons of the locus coeruleus (LC) belongs. LC neurons contain projections to the whole brain, and it is known that their discharge co-varies with pupil size. LC activation is necessary for eliciting task-related mydriasis. If chewing effects on cognitive performance are mediated by the LC, it is reasonable to expect that changes in cognitive performance are correlated to changes in task-related mydriasis. Two novel protocols are presented here to verify this hypothesis and document that chewing effects are not attributable to aspecific motor activation. In both protocols, performance and pupil size changes observed during specific tasks are recorded before, soon after, and half an hour following a 2 min period of either: a) no activity, b) rhythmic, bilateral handgrip, c) bilateral chewing of soft pellet, and d) bilateral chewing of hard pellet. The first protocol measures level of performance in spotting target numbers displayed within numeric matrices. Since pupil size recordings are recorded by an appropriate pupillometer that impedes vision to ensure constant illumination levels, task-related mydriasis is evaluated during a haptic task. Results from this protocol reveal that 1) chewing-induced changes in performance and task-related mydriasis are correlated and 2) neither performance nor mydriasis are enhanced by handgrip. In the second protocol, use of a wearable pupillometer allows measurement of pupil size changes and performance during the same task, thus allowing even stronger evidence to be obtained regarding LC involvement in the trigeminal effects on cognitive activity. Both protocols have been run in the historical office of Prof. Giuseppe Moruzzi, the discoverer of ARAS, at the University of Pisa.


Assuntos
Nível de Alerta/fisiologia , Locus Cerúleo/fisiologia , Pupila/fisiologia , Núcleo Motor do Nervo Trigêmeo/fisiologia , Cognição/fisiologia , Humanos , Locus Cerúleo/citologia , Masculino , Mastigação/fisiologia , Neurônios/fisiologia
17.
Nanomaterials (Basel) ; 9(10)2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31635259

RESUMO

This paper presents an investigation into the effect of graphene nanoplatelets (GNPs) as a means of improving the impact buckling performance and delamination propagation resistance of a recently developed 3D fiber-metal laminate (3D-FML). One of the highlights of the investigation is the examination of the performance of the GNP-reinforced resin at a sub-freezing temperature (-50 °C). 3D-FML beam specimens were subjected to axial impact of various intensities at room-temperature, while they were subjected to quasi-static axial compression load at the sub-freezing temperature. Moreover, the influence of two different surface preparation methods on the performance of the metallic/FRP interfaces of the hybrid system was also investigated in this study. Although the inclusion of the GNPs in the resin resulted in some gain in the buckling capacity of the 3D-FML, nevertheless, the results revealed that the lack of adequate chemical bond between the GNP-reinforced resin and the magnesium skins of the hybrid material system significantly limited the potential influence of the GNPs. Therefore, a cost-effective and practical alternative is presented that results in a significant improvement in the interfacial capacity.

18.
Nanomaterials (Basel) ; 7(11)2017 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29104278

RESUMO

This review paper aims at reporting some of the notable works carried out concerning the use of nanoparticles (NPs) as a means of improving the resistance of fiber-reinforced polymer composite materials (FRPs) and adhesively bonded joints (ABJs) to delamination initiation and propagation. Applications of various nanoparticles, such as carbon-based, ceramic-based and mineral-based are discussed. The main properties that have been considered for improving the delamination and fatigue resistance of FRPs are the interlaminar shear strength, fracture toughness, and fracture energy. On the other hand, cohesive and interfacial strengths have been the focused parameters in the works that considered enhancement of ABJs. The reported results indicate that inclusion of NPs in polymeric matrices leads to improvement of various material properties, even though some discrepancies in the results have been noted. Notwithstanding, additional research is required to address some of the issues that have not yet been tackled, some of which will be identified throughout this review article.

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