•A comprehensive and extensive review on thermal conductivity (TC) of transparent and flexible polymers (TFP) is first presented.•A variety of theoretical, empirical, and models based on numerical ...methods are discussed.•The TC enhancement of PDMS filled with carbon-based fillers and PI filled with ceramic fillers has been studied extensively in recent years. However, the TC of PET composites deserves more attention in future studies.•Better understandings in the research trend of polymer sciences, particularly the TFPs are provided.
Advances in micro and nanotechnology have motivated a number of recent studies on transparent and flexible polymers (TFP). In this study, a literature review on a thermal conductivity (TC) of these polymers containing fillers is first presented. Three major types of TFPs considered are poly-dimethyl siloxane (PDMS), polyethylene terephthalate (PET), and polyimides (PI). It was found from the literature review that carbon-based fillers, particularly multi-walled carbon nanotubes, and ceramic fillers have been considered as the most promising candidate for the TC enhancement of PDMS and PI, respectively. However, since very limited number of studies considered the TC of PET composites, it becomes a motivation for further investigations. This study provides better understandings in the research trends of polymer sciences, particularly the TFPs.
Honeycomb sandwich composites are suitable for making structural materials that are mainly characterized by their lightweight and high stiffness strength. The honeycomb structures filled with foam ...materials or granular materials concerning to the applications enhance the strength and the damping properties. In this paper, an emphasis has been provided for the comprehensive review of response of honeycomb sandwich structures in different conditions, namely, static, dynamic, and damping behaviors with and without filler material from an experimental and finite element simulation perspective. Various applications of honeycomb sandwich composites in different fields are also reviewed in this paper. Potential new directions in honeycomb sandwich composites are also identified in this paper in addition to the current practices. Conclusions and recommendations from different technical papers are reviewed by considering the honeycomb sandwich composites with filler materials. The given area of research seeks more scientific analysis, modeling, and experiments in future structural applications.
The optimal treatment of acne scarring is challenging because several factors need to be considered, including the type and number of scars, Fitzpatrick skin type, and the amount of downtime ...permissible to the patient. This second article in the continuing medical education series discusses the procedural treatments available for acne scarring, including the use of chemical peels, fillers, radiofrequency microneedling, lasers, and surgical procedures. The indications for each modality, evidence for its benefits, and the adverse effects are discussed. This section aims to help guide the reader select and implement the most appropriate treatment based on the patient's preferences, acne scarring, and skin type.
The success of hyaluronic acid (HA)-based dermal fillers, with more than 2 million minimally invasive procedures conducted in 2016 in the US alone, is due to their hygroscopic properties of ...biocompatibility and reversibility. The type and density of HA cross-linkage, as well as the manufacturing technology, may influence not only the in vivo persistence but also the safety profile of dermal fillers. 1,4-Butanediol diglycidyl ether (BDDE) is the cross-linker used in most market-leading HA fillers; 1,4-butanediol di-(propan-2,3-diolyl) ether (BDPE) is the major impurity obtained from the HA–BDDE cross-linking (HBC) process. In this work, a new process to obtain high purity HBC fillers was developed. A new HPLC-MS method was validated for the quantification of BDPE content in HBC dermal fillers. In vitro cytotoxicity of BDPE was evaluated in fibroblasts (IC50 = 0.48 mg/mL). The viscoelasticity was monitored during the shelf-life of the HBC-10% hydrogel and was correlated with in vitro hyaluronidase resistance and in vivo residence time in a rabbit model. This analysis showed that elasticity is the best parameter to predict the in vivo residence time. Finally, a series of parameters were investigated in certain marketed dermal fillers and were compared with the results of the HBC-10% hydrogel.
Abstract Our previous work highlighted how microscopic structural effects influence the sheet and contact resistance of electrically conductive adhesives (ECAs). Herein, we delve further by ...investigating how the contact and bulk resistivity of several ECAs that are based on the same formulation, but with different filler content, are correlated with the filler content. Additionally, two different filler geometries — high and low surface area (HSA and LSA) fillers — are combined in different ratios to maintain a similar viscosity and therefore processability. Hence, contact and bulk resistivities are also correlated with the different geometry ratios of these two fillers. As expected, it was found that the contact and bulk resistivities decreased when the filler content was increased. However, the magnitude of the decrease was found to depend strongly on the filler geometry ratio. At extreme filler geometry ratios, when the bulk is either mostly loaded with HSA‐fillers or mostly with LSA‐fillers, the impact of changes in the filler content on the bulk and contact resistivities is markedly different. The measured data is interpreted within the context of percolation theory and it is determined that the optimum ratio of the LSA and HSA Ag‐fillers investigated in this study is approximately 60:40 (for an epoxy‐based adhesive). This work has important ramifications for the design of ECAs, where cost considerations and the need to reduce silver resource usage demand the lowest (silver) filler content, but the demands of product performance point to higher filler content.
The growing demand for personalized implants and tissue scaffolds requires advanced biomaterials and processing strategies for the fabrication of three-dimensional (3D) structures mimicking the ...complexity of the extracellular matrix. During the last years, biofabrication approaches like 3D printing of cell-laden (soft) hydrogels have been gaining increasing attention to design such 3D functional environments which resemble natural tissues (and organs). However, often these polymeric hydrogels show poor stability and low printing fidelity and hence various approaches in terms of multi-material mixtures are being developed to enhance pre- and post-printing features as well as cytocompatibility and post-printing cellular development. Additionally, bioactive properties improve the binding to the surrounding (host) tissue at the implantation site. In this review we focus on the state-of-the-art of a particular type of heterogeneous bioinks, which are composed of polymeric hydrogels incorporating inorganic bioactive fillers. Such systems include isotropic and anisotropic silicates like bioactive glasses and nanoclays or calcium-phosphates like hydroxyapatite (HAp), which provide in-situ crosslinking effects and add extra functionality to the matrix, for example mineralization capability. The present review paper discusses in detail such bioactive composite bioink systems based on the available literature, revealing that a great variety has been developed with substantially improved bioprinting characteristics, in comparison to the pure hydrogel counterparts, and enabling high viability of printed cells. The analysis of the results of the published studies demonstrates that bioactive fillers are a promising addition to hydrogels to print stable 3D constructs for regeneration of tissues. Progress and challenges of the development and applications of such composite bioink approaches are discussed and avenues for future research in the field are presented.
Biofabrication, involving the processing of biocompatible hydrogels including cells (bioinks), is being increasingly applied for developing complex tissue and organ mimicking structures. A variety of multi-material bioinks is being investigated to bioprint 3D constructs showing shape stability and long-term biological performance. Composite hydrogel bioinks incorporating inorganic bioreactive fillers for 3D bioprinting are the subject of this review paper. Results reported in the literature highlight the effect of bioactive fillers on bioink properties, printability and on cell behavior during and after printing and provide important information for optimizing the design of future bioinks for biofabrication, exploiting the extra functionalities provided by inorganic fillers. Further functionalization with drugs/growth factors can target enhanced printability and local drug release for more specialized biomedical therapies.
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Background
Hyaluronic acid (HA) dermal fillers injection is a common procedure in patients with cosmetic needs. Concomitant pain is a major complaint among patients undergoing HA filler injections. ...Relevant research is limited and there is no consensus on pain management of dermal filler injection.
Objectives
To assist physicians in determining a more appropriate treatment approach, and to better provide treatment suggestions.
Methods
A nationwide (China) cross-sectional survey was conducted using questionnaires designed for physicians and patients, respectively. A total of 62 semi-structured questionnaires were administered to aesthetic physicians via face-to-face interview, whereas 123 online-based questionnaires were collected from patients who have ever undergone HA treatment. The collected questionnaire information was analyzed using descriptive statistics and content analysis.
Results
42 (67.74%) physicians observed that over 50% of their patients were concerned about pain during injection. 101 (82.11%) of patients were concerned about impending pain ≥5 points (a total score is 10) before injection. For preferred pain relief modalities, 48 (77.42%) physicians would choose a hyaluronic acid dermal filler with lidocaine, and 82 (66.67%) patients would choose anesthetic-containing products. 59 (95.16%) physicians who injected lidocaine-containing hyaluronic acid found patients had a comfortable treatment experience.
Conclusions
Pain management during hyaluronic acid dermal fillers injection is important from both perspectives of physicians and patients. This survey showed that compared with other analgesic methods, lidocaine-containing hyaluronic acid has offered a more satisfying experience. It also provides insights to physicians and patients in pain management.
Level of Evidence V
This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to Table of Contents or the online Instructions to Authors
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Eco‐friendly composite made of Timoho Fiber (TF) continuously developed to get the best performance to replace plastic‐based synthetic fibers. This study focuses on investigating physical ...characteristics, mechanical properties, thermal analysis, and the morphology of TF‐reinforced polyester composites by adding organic (egg shell powder‐ESP) and inorganic (aluminum powder‐AP) fillers. Hot press method was used in the composite fabrication with considered volume fraction of TF, organic, and inorganic fillers. The results showed that the density of TF‐polyester composites decreases with the increasing volume fraction of the fibers. For additional fillers, it was shown that AP was more effective to be used to improve density than ESP. The tensile and impact strength of the composite increased with increasing TF volume. However, the addition of ESP and AP fillers into the composite caused different mechanical characteristics. Filler addition increased the elasticity modulus, toughness, thermal resistance increased, while the tensile strength decreased. ESP and AP fillers provided the best thermal resistance due to the relatively high thermal conductivity of ±1700°C compared to composites without fillers and amorphous ESP fillers. SEM observation supported the analysis of TF‐polyester composite mechanical characteristics.
Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ...ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers or polymer matrix help in further improving the dielectric properties as compared to two-phase nanocomposites. Recent research has been focused on altering the dielectric properties of different materials while also maintaining their superior flexibility. Flexible polymer nanocomposites are the best candidates for application in various fields. However, certain challenges still present, which can be solved only by extensive research in this field.
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