Fabrication Of Various Types Research Articles

Carbon nanotube thin film pn junction diode with high-temperature tolerance using chemical dopants

Abstract Chemical doping of carbon nanotubes (CNTs) by adsorption with high-temperature-tolerant molecules is required for the fabrication of various types of electronic devices for their performance maintenance under harsh thermal conditions during the fabrication and operation processes. Here, we demonstrate the fabrication of CNT thin film pn junction diodes using a combination of 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile as a p-dopant and a complex salt of potassium hydroxide and benzo-18-crown-6 ether as an n-dopant. The fabricated devices demonstrated a reasonably stable rectifying behavior, even after heating to 200 °C for 300 min.

Development of Micro Electrical Discharge Machine and Micro-hole Machining Using Multiple Micro Electrodes

Recent advances in microtechnology have highlighted the need for fabricating microscopic parts with complex three-dimensional structures. This, in turn, has increased the demand for innovative tools. Micro electrical discharge machining (MEDM) is one such technique that has proven to be effective in producing parts that are difficult to fabricate using traditional manufacturing methods, such as micro shafts and micro holes. Therefore, this study focuses on the development of a specialized MEDM system that incorporates an optimized wire electrical discharge grinding (WEDG) module. Additionally, the study successfully fabricates microelectrodes for use as cutting tools using the MEDM/WEDG system. These micro-electrodes are then utilized in the precise fabrication of various types of multiple micro electrodes through the use of reverse electrical discharge machining (REDM). These multiple micro electrodes are subsequently employed in precise hole machining operations using MEDM. The application of REDM signifies a significant technological advancement in the precision fabrication of microstructures. Furthermore, it is expected to greatly enhance the versatility and efficiency of microtechnology manufacturing processes. Overall, REDM represents a new approach to manufacturing that is capable of producing more complex and high-precision microstructures.

Nanocrystal cellulose from diverse biological sources: Application and innovations

Cellulose is the most abundant renewable polymer on Earth which is extensively distributed in diverse ecosystems. It is present in higher plants, marine organisms, and also produced through microbial processes in organisms like algae, fungi, and bacteria. From an industrial perspective, the semicrystalline nature of cellulose present in different plant and microbial sources enables the fabrication of various types of nanocellulose, such as nanofibre and nanocrystals, through mechanical disintegration and chemical methods, respectively. Nanocellulose distinguishes itself as a sustainable, nonharmful, and biodegradable polymer. It will enable sustainable development for responsible consumption and production. Possessing a range of excellent properties, it can be seamlessly integrated into various materials. Research on nanocellulose is gaining momentum in response to current issues related to fossil fuels, including concerns about CO2 emissions, plastic pollution, and the need for renewable energy sources. This review addresses nanocrystals production method from cellulose found in agricultural, microbial sources, and its applications in fields such as materials science, electronics, medicine, and environmental science.

Bio‐inspired photonic crystals: Tailoring the dielectric building blocks to control the light propagation

AbstractPhotonic crystals have drawn tremendous attention in recent years owing to their unique optical properties and remarkable advantages in various applications such as bioassays, sensors and optical devices. Benefiting from the spatially ordered structures, the flow of visible light can be manipulated by photonic crystals in a controlled manner. In this review, we summarize recent progress toward bio‐inspired photonic crystals, including techniques for the construction of spatially ordered structures in diverse dimensions for photonic crystals, and strategies to manipulate the periodicity of the dielectric building blocks to control the light propagation in the presence of external stimuli. We start with the description of structure induced colors in nature with a systematic investigation to reveal the derivation of these colors, followed by a discussion on the design and fabrication of various types of bio‐inspired photonic crystals by manipulating the arrangement of dielectric building blocks. We also highlight the stimuli responsive photonic crystals with tunable optical properties and their applications in sensing and color display.

Recent Progress in Fabrication of Electrospun Nanofiber Membranes for Developing Physiological In Vitro Organ/Tissue Models.

Nanofiber membranes (NFMs), which have an extracellular matrix-mimicking structure and unique physical properties, have garnered great attention as biomimetic materials for developing physiologically relevant in vitro organ/tissue models. Recent progress in NFM fabrication techniques immensely contributes to the development of NFM-based cell culture platforms for constructing physiological organ/tissue models. However, despite the significance of the NFM fabrication technique, an in-depth discussion of the fabrication technique and its future aspect is insufficient. This review provides an overview of the current state-of-the-art of NFM fabrication techniques from electrospinning techniques to postprocessing techniques for the fabrication of various types of NFM-based cell culture platforms. Moreover, the advantages of the NFM-based culture platforms in the construction of organ/tissue models are discussed especially for tissue barrier models, spheroids/organoids, and biomimetic organ/tissue constructs. Finally, the review concludes with perspectives on challenges and future directions for fabrication and utilization of NFMs.

3D Printing Technology as a Promising Tool to Design Nanomedicine-Based Solid Dosage Forms: Contemporary Research and Future Scope.

3D printing technology in medicine is gaining great attention from researchers since the FDA approved the first 3D-printed tablet (Spritam®) on the market. This technique permits the fabrication of various types of dosage forms with different geometries and designs. Its feasibility in the design of different types of pharmaceutical dosage forms is very promising for making quick prototypes because it is flexible and does not require expensive equipment or molds. However, the development of multi-functional drug delivery systems, specifically as solid dosage forms loaded with nanopharmaceuticals, has received attention in recent years, although it is challenging for formulators to convert them into a successful solid dosage form. The combination of nanotechnology with the 3D printing technique in the field of medicine has provided a platform to overcome the challenges associated with the fabrication of nanomedicine-based solid dosage forms. Therefore, the major focus of the present manuscript is to review the recent research developments that involved the formulation design of nanomedicine-based solid dosage forms utilizing 3D printing technology. Utilization of 3D printing techniques in the field of nanopharmaceuticals achieved the successful transformation of liquid polymeric nanocapsules and liquid self-nanoemulsifying drug delivery systems (SNEDDS) to solid dosage forms such as tablets and suppositories easily with customized doses as per the needs of the individual patient (personalized medicine). Furthermore, the present review also highlights the utility of extrusion-based 3D printing techniques (Pressure-Assisted Microsyringe-PAM; Fused Deposition Modeling-FDM) to produce tablets and suppositories containing polymeric nanocapsule systems and SNEDDS for oral and rectal administration. The manuscript critically analyzes contemporary research related to the impact of various process parameters on the performance of 3D-printed solid dosage forms.

Electrospun Magnetic Nanofiber Mats for Magnetic Hyperthermia in Cancer Treatment Applications-Technology, Mechanism, and Materials.

The number of cancer patients is rapidly increasing worldwide. Among the leading causes of human death, cancer can be regarded as one of the major threats to humans. Although many new cancer treatment procedures such as chemotherapy, radiotherapy, and surgical methods are nowadays being developed and used for testing purposes, results show limited efficiency and high toxicity, even if they have the potential to damage cancer cells in the process. In contrast, magnetic hyperthermia is a field that originated from the use of magnetic nanomaterials, which, due to their magnetic properties and other characteristics, are used in many clinical trials as one of the solutions for cancer treatment. Magnetic nanomaterials can increase the temperature of nanoparticles located in tumor tissue by applying an alternating magnetic field. A very simple, inexpensive, and environmentally friendly method is the fabrication of various types of functional nanostructures by adding magnetic additives to the spinning solution in the electrospinning process, which can overcome the limitations of this challenging treatment process. Here, we review recently developed electrospun magnetic nanofiber mats and magnetic nanomaterials that support magnetic hyperthermia therapy, targeted drug delivery, diagnostic and therapeutic tools, and techniques for cancer treatment.

Latest Advances in Highly Efficient Dye-Based Photoinitiating Systems for Radical Polymerization.

Light-activated polymerization is one of the most important and powerful strategies for fabrication of various types of advanced polymer materials. Because of many advantages, such as economy, efficiency, energy saving and being environmentally friendly, etc., photopolymerization is commonly used in different fields of science and technology. Generally, the initiation of polymerization reactions requires not only light energy but also the presence of a suitable photoinitiator (PI) in the photocurable composition. In recent years, dye-based photoinitiating systems have revolutionized and conquered the global market of innovative PIs. Since then, numerous photoinitiators for radical polymerization containing different organic dyes as light absorbers have been proposed. However, despite the large number of initiators designed, this topic is still relevant today. The interest towards dye-based photoinitiating systems continues to gain in importance, which is related to the need for new initiators capable of effectively initiating chain reactions under mild conditions. In this paper we present the most important information about photoinitiated radical polymerization. We describe the main directions for the application of this technique in various areas. Attention is mainly focused on the review of high-performance radical photoinitiators containing different sensitizers. Moreover, we present our latest achievements in the field of modern dye-based photoinitiating systems for the radical polymerization of acrylates.

Control of the Nanopore Architecture of Anodic Alumina via Stepwise Anodization with Voltage Modulation and Pore Widening.

Control of the morphology and hierarchy of the nanopore structures of anodic alumina is investigated by employing stepwise anodizing processes, alternating the two different anodizing modes, including mild anodization (MA) and hard anodization (HA), which are further mediated by a pore-widening (PW) step in between. For the experiment, the MA and HA are applied at the anodizing voltages of 40 and 100 V, respectively, in 0.3 M oxalic acid, at 1 °C, for fixed durations (30 min for MA and 0.5 min for HA), while the intermediate PW is applied in 0.1 M phosphoric acid at 30 °C for different durations. In particular, to examine the effects of the anodizing sequence and the PW time on the morphology and hierarchy of the nanopore structures formed, the stepwise anodization is conducted in two different ways: one with no PW step, such as MA→HA and HA→MA, and the other with the timed PW in between, such as MA→PW→MA, MA→PW→HA, HA→PW→HA, and HA→PW→MA. The results show that both the sequence of the voltage-modulated anodizing modes and the application of the intermediate PW step led to unique three-dimensional morphology and hierarchy of the nanopore structures of the anodic alumina beyond the conventional two-dimensional cylindrical pore geometry. It suggests that the stepwise anodizing process regulated by the sequence of the anodizing modes and the intermediate PW step can allow the design and fabrication of various types of nanopore structures, which can broaden the applications of the nanoporous anodic alumina with greater efficacy and versatility.

An innovative approach to photolithography for optical recording of high-resolution two-dimensional structures in a negative SU8 photoresist by activation of up-conversion luminescence in Yb[formula omitted] and Tm[formula omitted] doped NaYF[formula omitted] nanoparticles

In this work, we demonstrate the success of an innovative approach to photolithographic recording of high-resolution 2D structures in thin films of hybrid inorganic nanoparticles/photoresist systems. This is done by utilising Yb3+, Tm3+ up-conversion luminescence in core–shell (β-NaYF4:Yb3+, Tm3+/ β-NaYF4)-structured nanoparticles (33.9 nm in size) mixed into a negative photoresist SU8. This approach is a promising alternative compared to traditional optical lithography performed by i-line UV radiation through a surface. Specially designed core–shell-structured nanoparticles were synthetised to emit Tm3+-characteristic up-conversion luminescence bands in the UV spectral region at 345 and 361 nm, and in the blue spectral region at 450 and 476 nm under IR excitation at 976 nm. The exposed elliptically shaped uniform structure, with dimensions of ∼160 ×320μm, was recorded in a ∼500 nm thin photosensitive layer by 1–5 min long infrared exposure when core–shell nanoparticles doped with Yb3+ and Tm3+ ions were mixed into negative photoresist SU8. Such hybrid systems of organic chromophores/UCNP/SU8 are highly prospective for the fabrication of various types of microstructures without damaging the light-sensitive organic compound, which is required in medicine (microsurgery, laboratory on a chip, etc.), telecommunications, military, sensor technologies and a wide range of photonic applications, e.g. for the fabrication of micro disk resonators used as active media in organic solid-state lasers.

Modern Digital Pediatric Dentistry with the Advent of Intraoral Sensors, Computer-Aided Design/Computer-Aided Manufacturing, and Three-dimensional Printing Technologies: A Comprehensive Review

The conventional methods of fabrication of the dental prosthesis/appliances in pediatric dental patients pose many challenges such as prolonged and multiple appointments, discrepancy in the accuracy of the fit of prosthesis, and cumbersome dental laboratory procedures. The conventional impression-making procedures in young children are regarded as quite cumbersome and difficult due to several clinical factors in dentistry. In recent years, digital Intra-Oral Sensors (IOS), three-dimensional printing (3D-printing) technology and computer-aided design/computer-aided manufacturing (CAD-CAM) technology have been described in existing literature related to different aspects of pediatric dentistry. The aim of the current study was to review the literature related to recent innovative applications of IOS, CAD-CAM, and 3D-printing technology in modern pediatric dentistry. Pediatric dental procedures involving the modern digital technologies such as IOS, CAD-CAM, and 3D-printing in the applications for the digital impression procedure and the fabrication of various types of dental appliances have the good potential to deliver optimum oral-health care in children. Furthermore, it can help in motivating the children and also in instilling the positive attitude and behavior toward dentistry.

Er:YAG/Yb:YAG nanopowders‐derived Er/Yb co‐doped yttrium aluminosilicate (YAS) fibers fabricated by UV‐curable nanocomposites for 1.5‐µm single‐frequency fiber lasers

AbstractThe rare‐earth (RE)‐doped yttrium aluminosilicate (YAS) glass fibers have demonstrated their unique advantages in single‐frequency lasers due to their high solubility of RE ions and high gain per unit length. However, the RE‐doped YAS fiber is usually fabricated by RE:YAG crystal or ceramic rods and melting‐in‐tube method, which depend heavily on RE:YAG crystal or ceramic rods and, thus, cannot adjust the fiber compositions effectively; there is little research on the multiple RE ions co‐doped YAS fiber deriving from RE:YAG crystal or ceramic rods. In present work, we developed a novel method to fabricate Er/Yb co‐doped YAS fibers efficiently. The Er:YAG and Yb:YAG nanopowders were fabricated by the coprecipitation method, and then the nanopowders were dispersed into liquid organic resin to form a novel UV‐curable nanocomposite, after curing, debinding, purifying, and drawing process, an Er/Yb co‐doped YAS fibers was fabricated, the absorption coefficients of the fiber was measured to be 17 dB/cm at 976 nm (2F7/2ground level to2F5/2level of Yb and4I15/2ground level to4I11/2level of Er) and 3.2 dB/cm at 1530 nm (4I15/2ground level to the high states of4I13/2of Er). A 1.5‐µm single‐frequency laser was constructed with the 2‐cm Er/Yb co‐doped YAS fiber. The longitudinal mode spacing was calculated to be 2.2 GHz with an effective cavity length of 4.5 cm, and the spectral signal‐to‐noise ratio was higher than 60 dB. To the best of our knowledge, it is the first time that Er/Yb co‐doped YAS fibers are fabricated using the UV‐curable nanocomposites. It indicates that this proposed technology is critical for the fabrication of various types of RE ions co‐doped YAS fibers and their applications in single‐frequency fiber lasers.

Rapid Assembly of Magnetoplasmonic Photonic Arrays for Brilliant, Noniridescent, and Stimuli-Responsive Structural Colors.

There are usually trade-offs between maximizing the color saturation and brightness and minimizing the angle-dependent effect in structural colors. Here, a magnetic field-induced assembly for the rapid formation of scalable, uniform amorphous photonic arrays (APAs) featuring unique structural colors is demonstrated. The magnetic field plays a fundamental role in photonic film formation, making this assembly technology versatile for developing structural color patterns on arbitrary substrates. The synergistic combination of surface plasmonic resonance of the Ag core and broadband light absorption of high refractive index (RI) Fe3 O4 shell in hybrid magnetoplasmonic nanoparticles (MagPlas NPs) enables breaking the trade-offs to produce brilliant, noniridescent structural colors with high tunability and responsiveness. These features enable the fabrication of various types of highly sensitive and reliable colorimetric sensors for naked-eye detection without sophisticated instruments. Furthermore, large-scale structural color patterns are effortlessly achieved, demonstrating the high potential of the present approach for full-spectrum displays, active coatings, and rewritable papers.

Principles of spintronic THz emitters

Significant progress has been made in answering fundamental questions about how and, more importantly, on what time scales interactions between electrons, spins, and phonons occur in solid state materials. These complex interactions are leading to the first real applications of terahertz (THz) spintronics: THz emitters that can compete with traditional THz sources and provide additional functionalities enabled by the spin degree of freedom. This Tutorial article is intended to provide the background necessary to understand, use, and improve THz spintronic emitters. A particular focus is the introduction of the physical effects that underlie the operation of spintronic THz emitters. These effects were, for the most part, first discovered through traditional spin-transport and spintronic studies. We, therefore, begin with a review of the historical background and current theoretical understanding of ultrafast spin physics that has been developed over the past 25 years. We then discuss standard experimental techniques for the characterization of spintronic THz emitters and—more broadly—ultrafast magnetic phenomena. We next present the principles and methods of the synthesis and fabrication of various types of spintronic THz emitters. Finally, we review recent developments in this exciting field including the integration of novel material platforms such as topological insulators as well as antiferromagnets and materials with unconventional spin textures.

Fabrication of Yb-doped silica micro-structured optical fibers from UV-curable nano-composites and their application in temperature sensing

A novel scheme for fabricating Yb-doped silica micro structured optical fibers and their application in high-temperature optical fiber sensing are reported. The Yb-doped silica micro structured optical fiber preforms consisted of Yb-doped silica core rods (0.1 wt% for Yb2O3) and holey pure silica claddings fabricated by UV-curable tube molding technology and digital light processing 3D printing technology, respectively. The silica preforms were drawn using the rod-in-tube method to Yb-doped silica micro structured optical fibers without severe distortion. The doped micro structured fibers were applied to high-temperature sensing from 296.15 to 653.15 K. The proposed technology is expected to be effective for the fabrication of various types of rare-earth-ion-doped silica micro structured optical fibers that can be used in fiber sensors, lasers, and amplifiers.

A Review of MOFs and Their Composites‐Based Photocatalysts: Synthesis and Applications

AbstractPhotocatalysis is considered to be a green and environment‐friendly technology since it can convert solar energy into other types of chemical energies. Over the past several years, metal‐organic frameworks (MOFs)‐based photocatalysts have received remarkable research interest due to their unique morphology, high photocatalytic performance, good chemical stability, easy synthesis, and low cost. In this review, the synthetic strategies of developing MOFs‐based photocatalysts are first introduced. Second, the recent progress in the fabrication of various types of MOFs composites photocatalysts is summarized. Third, the different applications including hydrogen evolution reaction, oxygen evolution reaction, overall water splitting, nitrogen reduction reaction, carbon dioxide reduction reaction as well as photodegradation of organic pollutants of MOFs‐based photocatalysts are summed up. Finally, the challenges and some suggestions for the future development of MOFs‐ and their composites‐based photocatalysts are also highlighted. It is expected that this report will help researchers to systematically devise and develop highly efficient photocatalysts based on MOFs and their composites.

Design of Temperature-Responsive Cell Culture Surfaces for Cell Sheet Engineering.

Temperature-responsive cell culture surfaces, which modulate cell attachment/detachment characteristics with temperature, have been used to fabricate cell sheets. Extensive study on fabrication of cell sheet with the temperature-responsive cell culture surface, manipulation, and transplantation of the cell sheet has established the interdisciplinary field of cell sheet engineering, in which engineering, biological, and medical fields closely collaborate. Such collaboration has pioneered cell sheet engineering, making it a promising and attractive technology in tissue engineering and regenerative medicine. This review introduces concepts of cell sheet engineering, followed by designs for the fabrication of various types of temperature-responsive cell culture surfaces and technologies for cell sheet manipulation. The development of various methods for the fabrication of temperature-responsive cell culture surfaces was also summarized. The availability of cell sheet engineering for the treatment and regeneration of damaged human tissue has also been described, providing examples of the clinical application of cell sheet transplantation in humans.

Engineered Celery-Structured Electrospun Fibers Surface and Its Initial Cell Attachment Ability Effect.

The fabrication of various types of scaffolds using electrospinning has been greatly researched for tissue engineering applications in recent times. The rapid initial cell adhesion in electrospun scaffolds helps in the rapid recovery of graft sites. The characteristics of nanofibrous scaffolds can be improved by modifying the topological features and surface of the nanofibers. Previous studies have shown that the scaffold structure is related to a cell attachment ability. In this study, we modified the surface of the fibers to mimic celery structure. It was confirmed that solvent evaporation and polymer concentration influenced the formation of the surface. This structural property can improve the initial adhesion ability of cells. Cellulose acetate solutions were prepared and tested in various concentrations (15 wt%, 20 wt%, and 30 wt%). Scanning electron microscopy (SEM), tensile test and cell experiments were performed to evaluate the physical properties and biocompatibility. The structure of the present nanofiber can be applied as a very effective scaffold and it is expected to have a positive effect in the tissue engineering field.

Polypropylene-Based Nanocomposite with Enhanced Aging Stability by Surface Grafting of Silica Nanofillers with a Silane Coupling Agent Containing an Antioxidant.

Simultaneous improvement in the mechanical properties and lifetime of polymer nanocomposites is crucially significant to further extend the versatility of polymer materials and reduce environmental impact. In this study, we fabricated reinforced polypropylene (PP)-based nanocomposites with improved aging stability by the addition of surface-modified well-ordered silica nanospheres with a silane coupling agent (SCA) containing hindered phenol antioxidant as a filler. Uniform grafting of the SCA on the filler surface contributed to homogeneous dispersion of the filler into the matrix, leading to improved properties (e.g., stiffness and ductility) and uniform distribution of the antioxidant component into the entire nanocomposite by filler dispersion. The grafting of SCA also likely provides an inhibitory effect on antioxidant migration, which leads to loss of polymer stability during the aging process. This novel idea for the material design of PP-based nanocomposites, which simultaneously enhances their mechanical properties and lifetime, is promising for application in the fabrication of various types of polymer nanocomposites.

Maskless, rapid manufacturing of glass microfluidic devices using a picosecond pulsed laser

Conventional manufacturing of glass microfluidic devices is a complex, multi-step process that involves a combination of different fabrication techniques, typically photolithography, chemical/dry etching and thermal/anodic bonding. As a result, the process is time-consuming and expensive, in particular when developing microfluidic prototypes or even manufacturing them in low quantity. This report describes a fabrication technique in which a picosecond pulsed laser system is the only tool required to manufacture a microfluidic device from transparent glass substrates. The laser system is used for the generation of microfluidic patterns directly on glass, the drilling of inlet/outlet ports in glass covers, and the bonding of two glass plates together in order to enclose the laser-generated patterns from the top. This method enables the manufacturing of a fully-functional microfluidic device in a few hours, without using any projection masks, dangerous chemicals, and additional expensive tools, e.g., a mask writer or bonding machine. The method allows the fabrication of various types of microfluidic devices, e.g., Hele-Shaw cells and microfluidics comprising complex patterns resembling up-scaled cross-sections of realistic rock samples, suitable for the investigation of CO2 storage, water remediation and hydrocarbon recovery processes. The method also provides a route for embedding small 3D objects inside these devices.