scholarly journals A Slot-Die Technique for the Preparation of Continuous, High-Area, Chitosan-Based Thin Films

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1566
Author(s):  
Oliver J. Pemble ◽  
Maria Bardosova ◽  
Ian M. Povey ◽  
Martyn E. Pemble
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
High Volume ◽  
Mechanical Anisotropy ◽  
Diverse Range ◽  
Direction Parallel ◽  
High Area ◽  
Wide Range ◽  
Slot Die ◽  
Potential Applications

Chitosan-based films have a diverse range of potential applications but are currently limited in terms of commercial use due to a lack of methods specifically designed to produce thin films in high volumes. To address this limitation directly, hydrogels prepared from chitosan, chitosan-tetraethoxy silane, also known as tetraethyl orthosilicate (TEOS) and chitosan-glutaraldehyde have been used to prepare continuous thin films using a slot-die technique which is described in detail. By way of preliminary analysis of the resulting films for comparison purposes with films made by other methods, the mechanical strength of the films produced was assessed. It was found that as expected, the hybrid films made with TEOS and glutaraldehyde both show a higher yield strength than the films made with chitosan alone. In all cases, the mechanical properties of the films were found to compare very favorably with similar measurements reported in the literature. In order to assess the possible influence of the direction in which the hydrogel passes through the slot-die on the mechanical properties of the films, testing was performed on plain chitosan samples cut in a direction parallel to the direction of travel and perpendicular to this direction. It was found that there was no evidence of any mechanical anisotropy induced by the slot die process. The examples presented here serve to illustrate how the slot-die approach may be used to create high-volume, high-area chitosan-based films cheaply and rapidly. It is suggested that an approach of the type described here may facilitate the use of chitosan-based films for a wide range of important applications.

scholarly journals Biodiversity of Secondary Metabolites Compounds Isolated from Phylum Actinobacteria and Its Therapeutic Applications

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4504
Author(s):  
Muhanna Al-shaibani ◽  
Radin Maya Saphira Radin Mohamed ◽  
Nik Sidik ◽  
Hesham Enshasy ◽  
Adel Al-Gheethi ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Bioactive Compounds ◽  
Extreme Environments ◽  
Software Tool ◽  
Gene Clusters ◽  
Well Being ◽  
Bioactive Substances ◽  
Diverse Range ◽  
Wide Range ◽  
Potential Applications

The current review aims to summarise the biodiversity and biosynthesis of novel secondary metabolites compounds, of the phylum Actinobacteria and the diverse range of secondary metabolites produced that vary depending on its ecological environments they inhabit. Actinobacteria creates a wide range of bioactive substances that can be of great value to public health and the pharmaceutical industry. The literature analysis process for this review was conducted using the VOSviewer software tool to visualise the bibliometric networks of the most relevant databases from the Scopus database in the period between 2010 and 22 March 2021. Screening and exploring the available literature relating to the extreme environments and ecosystems that Actinobacteria inhabit aims to identify new strains of this major microorganism class, producing unique novel bioactive compounds. The knowledge gained from these studies is intended to encourage scientists in the natural product discovery field to identify and characterise novel strains containing various bioactive gene clusters with potential clinical applications. It is evident that Actinobacteria adapted to survive in extreme environments represent an important source of a wide range of bioactive compounds. Actinobacteria have a large number of secondary metabolite biosynthetic gene clusters. They can synthesise thousands of subordinate metabolites with different biological actions such as anti-bacterial, anti-parasitic, anti-fungal, anti-virus, anti-cancer and growth-promoting compounds. These are highly significant economically due to their potential applications in the food, nutrition and health industries and thus support our communities’ well-being.

scholarly journals Biomimicry in Bio-Manufacturing: Developments in Melt Electrospinning Writing Technology Towards Hybrid Biomanufacturing

2019 ◽  
Vol 9 (17) ◽  
pp. 3540 ◽  
Author(s):  
Ferdows Afghah ◽  
Caner Dikyol ◽  
Mine Altunbek ◽  
Bahattin Koc
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Cell Attachment ◽  
Three Dimensional ◽  
Future Perspective ◽  
Melt Electrospinning ◽  
Wide Range ◽  
Challenges And Opportunities ◽  
Potential Applications ◽  
Homogeneous Cell

Melt electrospinning writing has been emerged as a promising technique in the field of tissue engineering, with the capability of fabricating controllable and highly ordered complex three-dimensional geometries from a wide range of polymers. This three-dimensional (3D) printing method can be used to fabricate scaffolds biomimicking extracellular matrix of replaced tissue with the required mechanical properties. However, controlled and homogeneous cell attachment on melt electrospun fibers is a challenge. The combination of melt electrospinning writing with other tissue engineering approaches, called hybrid biomanufacturing, has introduced new perspectives and increased its potential applications in tissue engineering. In this review, principles and key parameters, challenges, and opportunities of melt electrospinning writing, and particularly, recent approaches and materials in this field are introduced. Subsequently, hybrid biomanufacturing strategies are presented for improved biological and mechanical properties of the manufactured porous structures. An overview of the possible hybrid setups and applications, future perspective of hybrid processes, guidelines, and opportunities in different areas of tissue/organ engineering are also highlighted.

Semiconductor Thin Films Combined With Metallic Grating for Selective Improvement of Thermal Radiative Absorption/Emission

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
C. J. Fu ◽  
W. C. Tan
Keyword(s):  
Thin Films ◽  
High Energy ◽  
Semiconductor Layer ◽  
Metallic Grating ◽  
Rigorous Coupled Wave Analysis ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Potential Applications ◽  
Rigorous Coupled Wave ◽  
Energy Conversion Devices

We propose in this work a structure of semiconductor thin films combined with a one-dimensional metallic grating, which allows for selective improvement of thermal radiative absorptivity (also emissivity) of the structure. Both shallow and deep gratings are considered in this work. Our numerical results obtained with a 2D rigorous coupled-wave analysis algorithm demonstrate that the proposed structure exhibits enhanced spectral absorptivity for photon energy slightly above the gap energy of the semiconductor (silicon in this work). Furthermore, the selectively improved absorptivity can be obtained in a wide range of incidence angles. As such, much smaller thickness of the semiconductor layer is required to absorb the same amount of high energy photons than in a conventional Si-based photovoltaic device. In addition, absorptivity for low energy photons in the new structure is lower due to the smaller semiconductor layer thickness. Therefore, the new structure may have potential applications in energy conversion devices.

scholarly journals Characterization of Platinum-Based Thin Films Deposited by Thermionic Vacuum Arc (TVA) Method

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1796
Author(s):  
Sebastian Cozma ◽  
Rodica Vlǎdoiu ◽  
Aurelia Mandes ◽  
Virginia Dinca ◽  
Gabriel Prodan ◽  
...  
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Materials Science ◽  
Vacuum Arc ◽  
Silicon Substrates ◽  
Force Microscopy ◽  
Energy Evaluation ◽  
Transmission Electron ◽  
Potential Applications ◽  
Thermionic Vacuum Arc

The current work aimed to characterize the morphology, chemical, and mechanical properties of Pt and PtTi thin films deposited via thermionic vacuum arc (TVA) method on glass and silicon substrates. The deposited thin films were characterized by means of a scanning electron microscope technique (SEM). The quantitative elemental microanalysis was done using energy-dispersive X-ray spectroscopy (EDS). The tribological properties were studied by a ball-on-disc tribometer, and the mechanical properties were measured using nanoindentation tests. The roughness, as well as the micro and nanoscale features, were characterized using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The wettability of the deposited Pt and PtTi thin films was investigated by the surface free energy evaluation (SFE) method. The purpose of our study was to prove the potential applications of Pt-based thin films in fields, such as nanoelectronics, fuel cells, medicine, and materials science.

Effects of environmental exposures on carbon fiber epoxy composites protected by metallic thin films

2019 ◽  
Vol 54 (2) ◽  
pp. 167-177 ◽  
Author(s):  
Arash Afshar ◽  
Dorina Mihut ◽  
Pengyu Chen
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Carbon Fiber ◽  
Surface Morphology ◽  
Environmental Conditions ◽  
Epoxy Composite ◽  
Epoxy Composites ◽  
Metallic Thin Films ◽  
Wide Range ◽  
Carbon Fiber Epoxy

Carbon fiber epoxy composites have a wide range of applications in aerospace, construction, and automotive industries due to their good mechanical properties and lightweight characteristics. Carbon fiber epoxy composite structures are typically intended for service in corrosive and hostile environmental conditions. Therefore, development of coatings which are able to protect carbon fiber epoxy composite laminates against prolonged and harsh environmental conditions such as ultraviolet radiation and moisture deems critical. This paper offers a novel method for environmental protection of fiber-reinforced polymer composites by applying thin metallic films on composites' surface as coating materials. In order to investigate the protective properties of metallic thin films, copper and aluminum coatings were deposited on the surface of carbon fiber epoxy specimens by using direct current magnetron-sputtering technique, and then mechanical properties and surface morphology of specimens were monitored during the course of accelerated environmental exposure. Both metallic coatings showed good adhesion to carbon fiber epoxy samples during environmental aging and provided protection for the specimens' surface against environmental degradation. The correlation between flexural properties and surface morphology of carbon fiber epoxy specimens is also presented.

Plasma Etching of PLT Thin Films and Bulk PLZT Using Fluorine- and Chlorine-Based Gases

1990 ◽  
Vol 200 ◽  
Author(s):  
M. R. Poor ◽  
A. M. Hurd ◽  
C. B. Fleddermann ◽  
A. Y. Wu
Keyword(s):  
Thin Films ◽  
Integrated Circuits ◽  
Substrate Temperature ◽  
Plasma Etching ◽  
Room Temperature ◽  
Removal Rate ◽  
Ceramic Film ◽  
Wide Range ◽  
Potential Applications ◽  
Silicon Based

ABSTRACTPotential applications for ferroelectric thin films include both electronic and optoelectronic devices. In order to integrate a large number of devices on a single ceramic film or to incorporate ceramic devices with silicon-based integrated circuits, suitable film patterning techniques must be developed. In this study, the use of plasma etching for device patterning of PLT thin films has been explored using a dc hollow cathode discharge with HCl and CF4 etching gases. At room temperature, no etching of material is discernable. As the substrate temperature is increased, however, relatively rapid etching takes place. Etch rates for PLT thin films as high as 6500 Å/hour were measured. Etching occurred in both chlorinated and fluorinated plasmas, but at considerably different rates. The etch rate is enhanced by a factor of six by using a combination of HCl and CF4 in the plasma. After etching, the stoichiometry of the film, measured by energy dispersive spectroscopy (EDS), varied greatly with changes in substrate temperature. Although the removal rate for each element is different, all traces of lead, titanium, and lanthanum can be removed from the substrate over a wide range of plasma etching conditions.

Semiconductor Thin Films Combined With Metallic Grating for Selective Improvement of Thermal Radiative Absorption/Emission

2008 ◽  
Author(s):  
Ceji Fu ◽  
Wenchang Tan
Keyword(s):  
Thin Films ◽  
Semiconductor Layer ◽  
Surface Polaritons ◽  
Metallic Grating ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Diffracted Waves ◽  
Potential Applications ◽  
Rigorous Coupled Wave ◽  
Grating Region

We propose in this work a structure of semiconductor thin films combined with a one-dimensional metallic grating which allows for selective improvement of thermal radiative absorptivity (also emissivity) of the structure. We numerically demonstrate with a 2-D rigorous coupled-wave analysis (RCWA) algorithm that the proposed structure exhibits enhanced spectral absorptivity (for p-polarization) for photon energy slightly above the gap energy of the semiconductor (silicon in this work). The enhanced absorptivity is explained as due to excitations of surface polaritons (SPs) in the grating region, along with interactions of multiple-order diffracted waves in the semiconductor layer. Furthermore, the enhanced absorptivity of the structure can be achieved for a wide range of incidence angles so that it may have potential applications in energy conversion purposes.

scholarly journals A Review on Brittle Fracture Nanomechanics by All-Atom Simulations

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 1050 ◽  
Author(s):  
Sandeep P. Patil ◽  
Yousef Heider
Keyword(s):  
Mechanical Properties ◽  
Brittle Fracture ◽  
Brittle Materials ◽  
Md Simulations ◽  
Theoretical Background ◽  
Primary Concern ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Wide Range ◽  
Potential Applications

Despite a wide range of current and potential applications, one primary concern of brittle materials is their sudden and swift collapse. This failure phenomenon exhibits an inability of the materials to sustain tension stresses in a predictable and reliable manner. However, advances in the field of fracture mechanics, especially at the nanoscale, have contributed to the understanding of the material response and failure nature to predict most of the potential dangers. In the following contribution, a comprehensive review is carried out on molecular dynamics (MD) simulations of brittle fracture, wherein the method provides new data and exciting insights into fracture mechanism that cannot be obtained easily from theories or experiments on other scales. In the present review, an abstract introduction to MD simulations, advantages, current limitations and their applications to a range of brittle fracture problems are presented. Additionally, a brief discussion highlights the theoretical background of the macroscopic techniques, such as Griffith’s criterion, crack tip opening displacement, J-integral and other criteria that can be linked to the fracture mechanical properties at the nanoscale. The main focus of the review is on the recent advances in fracture analysis of highly brittle materials, such as carbon nanotubes, graphene, silicon carbide, amorphous silica, calcium carbonate and silica aerogel at the nanoscale. These materials are presented here due to their extraordinary mechanical properties and a wide scope of applications. The underlying review grants a more extensive unravelling of the fracture behaviour and mechanical properties at the nanoscale of brittle materials.

Versatile Lead-Free Solder Electroplating Products for Advanced Bumping Technologies

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 001603-001621
Author(s):  
Inho Lee ◽  
Regina Cho ◽  
Lou Grippo ◽  
Yen-Lin Taylor ◽  
Wayne Baldelli ◽  
...  
Keyword(s):  
Alloy Composition ◽  
High Volume ◽  
Die Design ◽  
Lead Free ◽  
Next Generation ◽  
Production Lines ◽  
Diverse Range ◽  
Wide Range ◽  
Snag Solder ◽  
High Yields

Lead-free SnAg solder bumps deposited by electroplating are used extensively in high volume production lines for a number of new bumping technologies including C4 bumps, Cu pillars capped with SnAg solder and 3D microbumps. New bumping technologies present their challenging requirements such as tightly controlled thickness uniformity, alloy composition uniformity and avoidance of reflow voids to create high yields and low defects. To meet these requirements, SnAg plating chemistry must deliver strong performance over a wide range of applications. Traditional device manufacturers, wafer foundry companies and Outsourced Assembly and Test (OSAT) companies are manufacturing a number of different types of bumped wafers in their production lines; a diverse range of die design and pattern densities, thin and thick resist film wafers, mushroom and in-via plating, and wide range of plating rate. The variety and complexity of bumping wafers have challenged SnAg plating chemistries to meet tight requirements in terms of running cost saving and high production yield. Hence, development of versatile and robust chemistries for electroplating is critical to overcome these challenges In view of all these challenges and unmet needs in the market, Dow focused its efforts on developing a brand-new additive system for SnAg plating. On the one hand, we tapped into our know-how on solder plating to establish correlations between various types of end-user requirements and experiences to fundamental electrochemistry response. On the other hand, 300mm in-house plating and process tools are leveraged to speed up the feedback process and provide pilot run data. At the end, this highly iterative approach enabled us to optimize the performance of the chemistry without sacrifice on design space. In this paper, we will discuss next generation of SnAg electroplating products capable of achieving versatile performance requirements over a wide range of applications. The bump height WID co-planarity% ((hmax-hmin)/2havg ×100) was achieved less than ±5% over the wide range of current density from 4 ASD to 12 ASD. Smooth surface morphology, narrow Ag alloy composition distribution less than ±0.2% across the 300mm wafers, and reflow void free were observed. An optimized formulation of the next generation SnAg products was successfully demonstrated plating capability on various bumping technologies such as C4 bumping, Cu pillars capped SnAg solders and micro bumps meeting plating requirements.

scholarly journals Excitons in 2D perovskites for ultrafast terahertz photonic devices

2020 ◽  
Vol 6 (8) ◽  
pp. eaax8821 ◽  
Author(s):  
Abhishek Kumar ◽  
Ankur Solanki ◽  
Manukumara Manjappa ◽  
Sankaran Ramesh ◽  
Yogesh Kumar Srivastava ◽  
...  
Keyword(s):  
Flexible Substrate ◽  
Photonic Devices ◽  
Solution Processed ◽  
Diverse Range ◽  
Light Emitting ◽  
Free Carriers ◽  
Wide Range ◽  
Potential Applications ◽  
Self Assembled ◽  
Terahertz Fields

In recent years, two-dimensional (2D) Ruddlesden-Popper perovskites have emerged as promising candidates for environmentally stable solar cells, highly efficient light-emitting diodes, and resistive memory devices. The remarkable existence of self-assembled quantum well (QW) structures in solution-processed 2D perovskites offers a diverse range of optoelectronic properties, which remain largely unexplored. Here, we experimentally observe ultrafast relaxation of free carriers in 20 ps due to the quantum confinement of free carriers in a self-assembled QW structures that form excitons. Furthermore, hybridizing the 2D perovskites with metamaterials on a rigid and a flexible substrate enables modulation of terahertz fields at 50-GHz modulating speed, which is the fastest for a solution-processed semiconductor-based photonic device. Hence, an exciton-based ultrafast response of 2D perovskites opens up large avenues for a wide range of scalable dynamic photonic devices with potential applications in flexible photonics, ultrafast wavefront control, and short-range wireless terahertz communications.

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