Delicate Materials Research Articles

Layer thickness measurement of ceramic systems with a numerical model for flash thermography

Thermography is a non-destructive testing technique which is non-contacting as well as imaging and therefore advantageous for delicate materials. It is more widely used for qualitative evaluation but can also provide data for a quantitative analysis when the heat source is actively controlled. With flash thermography, fast diffusion or conduction processes can be monitored, providing an effective method for the inspection of metals and thin coatings. Ceramic layered systems are used as thermal barrier coatings, for example on turbine blades. Gas turbines with such blades can be operated at higher temperatures, which leads to an increase in efficiency. To fully exploit this advantage, the properties and thickness of the coating must be within a predefined parameter range. Due to the challenging and hard to monitor manufacturing process, the coating must be examined afterwards. With the help of a numerical model using a finite difference solution, multiple material parameters such as thermal conductivity and layer thickness can be determined simultaneously with nonlinear regression fitting. During the research presented herein, a four-stepped sample of ceramic coatings on an Inconel steel basis is examined and the thermographic data analysed. After the thermographic measurements, the sample was cut, embedded in resin, and polished. The scanning electron microscopy images and measurements serve as the reference values to compare the extracted parameters to.

Understanding the unique S-scheme charge migration in triazine/heptazine crystalline carbon nitride homojunction

Understanding charge transfer dynamics and carrier separation pathway is challenging due to the lack of appropriate characterization strategies. In this work, a crystalline triazine/heptazine carbon nitride homojunction is selected as a model system to demonstrate the interfacial electron-transfer mechanism. Surface bimetallic cocatalysts are used as sensitive probes during in situ photoemission for tracing the S-scheme transfer of interfacial photogenerated electrons from triazine phase to the heptazine phase. Variation of the sample surface potential under light on/off confirms dynamic S-scheme charge transfer. Further theoretical calculations demonstrate an interesting reversal of interfacial electron-transfer path under light/dark conditions, which also supports the experimental evidence of S-scheme transport. Benefiting from the unique merit of S-scheme electron transfer, homojunction shows significantly enhanced activity for CO2 photoreduction. Our work thus provides a strategy to probe dynamic electron transfer mechanisms and to design delicate material structures towards efficient CO2 photoreduction.

Applications of the internet of things in library and data privacy

The Internet of Things (IoT) has emerged as a promising technology with trans formative potential in various industries, including libraries. An overview of the applications of IoT in libraries highlights the importance of data privacy considerations in the context of IoT adoption. Libraries are increasingly leveraging IoT to enhance their operations and improve user experiences. Intelligent library management systems, including automated inventory tracking, self-checkout systems, and intelligent shelf management, streamline library processes and optimize resource utilization. Environmental monitoring using IoT sensors ensures the preservation of delicate materials by monitoring temperature, humidity, and air quality in library spaces. IoT-enabled occupancy tracking provides valuable insights into space utilization, enabling effective resource allocation and planning. This paper emphasises the need for libraries to find a balance between harnessing the benefits of IoT technologies and safeguarding patrons' data privacy. By implementing appropriate privacy safeguards, libraries can leverage the potential of IoT to enhance their services while maintaining the trust and privacy of their users.

The Impact of Taiwan’s Status on US-Chinese Relations Under President Joe Biden

The international standing has an impact on the strategic importance of the country in its relations with other regional and international countries. The strategic position of Taiwan has an impact on the US-Chinese relations, as it is one of the most important issues that raise dispute between the two countries. The while the Chinese consider Taiwan is an ancient legacy of their republic, and an integral part of it, the Americans consider it as an area linking the U.S. to the Asia-Pacific region, through which it intends to help its allies (Japan and South Korea). Moreover, Taiwan has huge economic importance as it is one of the largest manufacturers of electronic chips and semiconductors. This fact represents one of the most important issues of disagreement between the United States, which seeks to seize these delicate materials in its delicate industries, and China, which is trying to monopolize them to be the only country producing these materials, because it owns 5% of the electronic chip industries, and Taiwan owns 75% of its industries in the world. If the Chinese succeed in returning Taiwan, they will acquire thin industries at a rate of 80% of the total industries in the world.

Pulsed laser micro drilling act on Perspex intended for microfluidic devices

An amorphous material with excellent shape memory effect (SME) like Perspex is a versatile material with broad applications in the bio-related field. Moreover, its extravagant properties like biological behavior, antimicrobial capacity, and porosity make it a choice for ophthalmologic devices, drug delivery, and microfluidic-based chromatography. However, its brittleness property and the formation of brittle-ductile transition make it a complex and delicate material for machining processes. A laser beam is an idiosyncratic tool used in engineering to biomedical fields. Compared to other lasers, the CO2 laser has a longer wavelength of 10.6 µm, which makes it the best choice for processing transparent material like Perspex. In this research CO2 laser micro-drilling (CLMD) act has been performed to design micro-holes on Perspex by tailoring the scan tracks of the laser. The movement of scanning tracks was controlled, and the beam functionalities' process windows were handled through adequate parametric settings like scan mode, machining speed, power, and pulsed frequency. The selection of optimal control factors is crucial for the adequate dimensional characteristics of holes, such as circularity and conicity. In continuation, multi-response optimization using RSM was employed to acquire the desired values of CLMD responses. Thus, the current CLMD approach may emanate its proprietary in fabricating micro-holes designed for a microfluidic device as an integrated inlet–outlet connector for fluidic manipulation. The findings of this research may be a worthy contribution to the biomedical field, as the designed holes by the current process on Perspex have not yet been addressed in any articles.

In situ synthesis of ultrasmall NaTi2(PO4)3 nanocube decorated carbon nanofiber network enables ultrafast and superstable rocking-chair capacitive deionization

Faradic-based capacitive deionization (CDI), as an important derivative of conventional CDI, has received wide attention in the desalination community. Yet, oriented from its intrinsic ion storage mechanism, faradic-based CDI has been plagued by several serious issues (e.g., imbalanced ion storage capacity, low desalination rate, and poor cycling stability), which greatly constrained its further development. Herein, we put forward an innovative strategy by using carbon nanofiber-reinforced NaTi2(PO4)3 (eCNF/NTP) as the core material (for Na+-capturing) and further coupling it with rational rocking-chair capacitive deionization (RCDI) cell architecture. Of note, owing to the unique 3D network structure of eCNF/NTP that not only provides sufficient redox-activate sites but also offers a rigid network structure to prevent the potential aggregation during cycling, as well as the rational RCDI symmetric cell architecture to avoid the imbalanced cation and anion storage capacity, the RCDI system equipping with eCNF/NTP electrode displays an excellent desalination performance (desalination capacity: 168.2 mg g−1; desalination rate: 0.46 mg g−1 s−1) with outstanding cycling stability (only 6 % desalination capacity degradation after 80 cycles). This work is interesting because it showcases the critical importance of both delicate material design and rationalized cell architecture in addressing the bottleneck issue of CDI, which could shed light on the future development of other high-performance desalination systems.

Thermally-modulated shape transition at the interface of soft gel filament and hydrophobic substrate

A liquid filament may pinch off into different shapes on interacting with a soft surface, as modulated by the interplay of inertial, capillary, and viscous forces. While similar shape transitions may intuitively be realized for more complex materials such as soft gel filaments as well, their intricate controllability towards deriving precise and stable morphological features remains challenging, as attributed to the complexities stemming from the underlying interfacial interactions over the relevant length and time scales during the sol–gel transition process. Circumventing these deficits in the reported literature, here we report a new means of precisely-controlled fabrication of gel microbeads via exploiting thermally-modulated instabilities of a soft filament atop a hydrophobic substrate. Our experiments reveal that abrupt morphological transitions of the gel material set in at a threshold temperature, resulting in spontaneous capillary thinning and filament breakup. We show that this phenomenon may be precisely modulated by an alteration in the hydration state of the gel material that may be preferentially dictated by its intrinsic glycerol content. Our results demonstrate that the consequent morphological transitions give rise to topologically-selective microbeads as an exclusive signature of the interfacial interactions of the gel material with the deformable hydrophobic interface underneath. Thus, intricate control may be imposed on the spatio-temporal evolution of the deforming gel, facilitating the inception of highly ordered structures of specific shapes and dimensionalities on demand. This is likely to advance the strategies of long shelf-life analytical biomaterial encapsulations via realizing one-step physical immobilization of bio-analytes on the bead surfaces as a new route to controlled materials processing, without demanding any resourced microfabrication facility or delicate consumable materials.

Up-shifting the desalination rate limit of capacitive deionization via integrating chloride-capturing Bi nanocluster with flow-through cell architecture

Faradic electrode-directed capacitive deionization (faradic-based CDI) as a green and eco-friendly technique is particularly promising in addressing the freshwater crisis, but its practical applications are plagued by the sluggish desalination kinetic. After deciphering its dynamic desalination process, two rate-determine steps (RDS) are identified, i.e., the ion diffusion inside the faradic electrode (RDS #1) and mass transfer process in the electrolyte (RDS #2). Therefore, we propose a synergetic strategy to upshift the desalination rate limit of faradic-based CDI through the integration of delicate material design with rational cell architecture. Specifically, deploying ultrasmall Bi nanoclusters impregnated carbon nanofibers (Bi NCs@CNF) as chloride-capturing electrodes and constructing a flow-through CDI (FT-CDI) system to accelerate the diffusion process (RDS #1) and shorten the mass transfer pathway (RDS #2), respectively. As expected, Bi NCs@CNF-based FT-CDI performs super-fast desalinization (0.56 mg g−1 s−1) and excellent cyclic stability. Taken together, our study opens an avenue in upshifting the desalination kinetics of faradic-based CDI based on the joint power of both “material design” and “cell architecture”, which may motivate the development of highly-efficient desalination systems.

Optimize the process parameters of wire EDM and to analyse the welding characteristics of tig welding joints using AISI 308

Wire Cut EDM technique is widely used to make small and precision cuts. Generally, a material with fragile geometry and hard structure is cut using a wire cut EDM. The main advantage of this method is that, it is a non-conventional machining process therefore it does not have a contact between the tool (wire) and the workpiece. This advantage gives it an edge over other machining techniques and it makes the process capable of machining even the weak structured and delicate materials. In the present experimental work, by using various machining parameters (Pulse on Time, Pulse off Time, and Wire Speed) were optimized using Taguchi’s L9 orthogonal array. Welding is most the important industrial processes, therefore lots of techniques have been developed to get an efficient and low-cost welding process for different types of materials. In this we will discuss about the welding characteristics of the of tig welding joints produced using different currents. That is, by changing the voltages for the number of passes to improve and strengthen the welded joint The research work aims to optimize the wire cut EDM process parameters for AISI 308 steel and analyze the welding characteristics of Tungsten Inert Gas (TIG) welded joints of the same material. The study intends to find the optimum combination of process parameters that would lead to the highest material removal rate, lowest wear rate, and best tensile properties of the material.

A general one-step plug-and-probe approach to top-gated transistors for rapidly probing delicate electronic materials.

The miniaturization of silicon-based electronics has motivated considerable efforts in exploring new electronic materials, including two-dimensional semiconductors and halide perovskites, which are usually too delicate to maintain their intrinsic properties during the harsh device fabrication steps. Here we report a convenient plug-and-probe approach for one-step simultaneous van der Waals integration of high-k dielectrics and contacts to enable top-gated transistors with atomically clean and electronically sharp dielectric and contact interfaces. By applying the plug-and-probe top-gate transistor stacks on two-dimensional semiconductors, we demonstrate an ideal subthreshold swing of 60 mV per decade. Using this approach on delicate lead halide perovskite, we realize a high-k top-gate CsPbBr3 transistor with a low operating voltage and a very high two-terminal field-effect mobility of 32 cm2 V-1 s-1. This approach can be extended to centimetre-scale MoS2 and perovskite and generate top-gated transistor arrays, offering a rapid and convenient way of accessing intrinsic properties of delicate emerging materials.

Effectiveness of hybrid Al2O3-TiO2 nano cutting fluids application in CNC turning process

The purpose of this study is to evaluate the effectiveness of hybrid Al2O3-TiO2 nano-cutting fluid in the turning process application under the selected significant machining parameters consisting of nano concentration, depth of cut and feed rate. The preparation of aqueous hybrid Al2O3-TiO2 water-based nano-cutting fluids and their application as the cutting fluid in turning operations are undertaken. The Al2O3-TiO2 hybrid nano-cutting fluids were prepared through a one-step method; by dispersing nanoparticles of Al2O3 (average diameter 30 nm) and TiO2 (average diameter 30-50 nm) in CNC coolant based at four different volume concentrations (1%, 2%, 3%, 4%). The effectiveness of turning cutting performance, namely cutting temperature (°C), average surface roughness (Ra), and tool wear (%), were assessed via air-assisted nano cutting fluids impinged through MQL setup in turning of Aluminium Alloy AA7075. The response surface method (RSM) was employed in the design of the experiment (DOE). The lowest cutting temperature, surface roughness, and tool wear of 25.8°C, 0.494 µm, and 0.0107%, are obtained, respectively, when the combinations of hybrid nano cutting fluid concentration of 4%, feed rate value of 0.1 mm/rev, and 0.3 mm depth of cut is used. The result in this paper is based on the experimental study of Al2O3-TiO2 hybrid nano-cutting fluid using CNC turning operation. The process focuses on the finishing process by using a finishing insert. Further work using roughing process may be suggested to observe the better performance of this cutting process using nano-cutting fluid towards reducing the wear rate. The use of Al2O3-TiO2 hybrid nano-cutting fluid coupled with MQL in the CNC turning process is considered a new method. Machining soft and delicate materials such as Aluminium should consider using this combination technique since it lowers the cutting temperature and removes the chips, reducing the adhesive wear. The hybrid nano-cutting fluid can replace the conventional cutting fluid and will perform better if combined with the MQL cooling technique; this new method should be considered by major industry players that require a high-precision finished product such as the product that involves aircraft and aerospace applications.

Blistering of color coated steel: Use of broad ion beam milling to examine degradation phenomena and coating defects

Broad ion beam (BIB) cross-section preparation is emerging as a preferred technique to polish delicate multiphase materials. This paper presents an examination of coating degradation phenomena obtained with BIB sample preparation and scanning electron microscopy (SEM) characterization. Early-stage humidity-induced coating degradation included oxidization of zinc and break-up of metal/coating and corrosion inhibitor particle/coating bonding. Ongoing corrosion product formation and accumulation of water within the coating finally led to evolution of macroscopic blisters. These degradation stages were successfully observed from pristine cross-sections, even when blisters did not yet appear on the coating surface, and the technique significantly facilitated distinguishing zinc corrosion-based blistering from other coating defects.

Edge-Contact MoS2 Transistors Fabricated Using Thermal Scanning Probe Lithography.

The science and engineering of two-dimensional materials (2DMs), in particular, of 2D semiconductors, is advancing at a thriving pace. It is well known that these delicate few-atoms thick materials can be damaged during the processing toward their integration into final devices. Thermal scanning probe lithography (t-SPL) is a gentle alternative to the typically used electron beam lithography to fabricate these devices avoiding the use of electrons, which are well known to deteriorate the 2DMs’ properties. Here, t-SPL is used for the fabrication of MoS2-based field effect transistors (FETs). In particular, the use of t-SPL is demonstrated for the first time for the fabrication of edge-contact MoS2 FETs, combining the hot-tip patterning and Ar+ milling to etch the 2DM. To avoid contamination of the contact interface by atmospheric gas molecules, etching and metal deposition are performed without breaking the vacuum conditions in between. With this process, edge-contact MoS2 FETs are successfully fabricated and characterized. On/off ratios up to 108 and 109 are obtained at room temperature in air and vacuum, respectively, i.e., comparable with the best values reported in the literature.

In vitro investigation of protein assembly by combined microscopy and infrared spectroscopy at the nanometer scale

The nanoscale structure and dynamics of proteins on surfaces has been extensively studied using various imaging techniques, such as transmission electron microscopy and atomic force microscopy (AFM) in liquid environments. These powerful imaging techniques, however, can potentially damage or perturb delicate biological material and do not provide chemical information, which prevents a fundamental understanding of the dynamic processes underlying their evolution under physiological conditions. Here, we use a platform developed in our laboratory that enables acquisition of infrared (IR) spectroscopy and AFM images of biological material in physiological liquids with nanometer resolution in a cell closed by atomically thin graphene membranes transparent to IR photons. In this work, we studied the self-assembly process of S-layer proteins at the graphene-aqueous solution interface. The graphene acts also as the membrane separating the solution containing the proteins and Ca2+ ions from the AFM tip, thus eliminating sample damage and contamination effects. The formation of S-layer protein lattices and their structural evolution was monitored by AFM and by recording the amide I and II IR absorption bands, which reveal the noncovalent interaction between proteins and their response to the environment, including ionic strength and solvation. Our measurement platform opens unique opportunities to study biological material and soft materials in general.

Presolar Stardust in Asteroid Ryugu

We have conducted a NanoSIMS-based search for presolar material in samples recently returned from C-type asteroid Ryugu as part of JAXA's Hayabusa2 mission. We report the detection of all major presolar grain types with O- and C-anomalous isotopic compositions typically identified in carbonaceous chondrite meteorites: 1 silicate, 1 oxide, 1 O-anomalous supernova grain of ambiguous phase, 38 SiC, and 16 carbonaceous grains. At least two of the carbonaceous grains are presolar graphites, whereas several grains with moderate C isotopic anomalies are probably organics. The presolar silicate was located in a clast with a less altered lithology than the typical extensively aqueously altered Ryugu matrix. The matrix-normalized presolar grain abundances in Ryugu are ppm for O-anomalous grains, ppm for SiC grains, and ppm for carbonaceous grains. Ryugu is isotopically and petrologically similar to carbonaceous Ivuna-type (CI) chondrites. To compare the in situ presolar grain abundances of Ryugu with CI chondrites, we also mapped Ivuna and Orgueil samples and found a total of 15 SiC grains and 6 carbonaceous grains. No O-anomalous grains were detected. The matrix-normalized presolar grain abundances in the CI chondrites are similar to those in Ryugu: ppm SiC and ppm carbonaceous grains. Thus, our results provide further evidence in support of the Ryugu–CI connection. They also reveal intriguing hints of small-scale heterogeneities in the Ryugu samples, such as locally distinct degrees of alteration that allowed the preservation of delicate presolar material.

Spin injection by spin–charge coupling in proximity induced magnetic graphene

Within the field of spintronics major efforts are directed towards developing applications for spin-based transport devices made fully out of two-dimensional materials. In this work we present an experimental realization of a spin-valve device where the generation of the spin signal is exclusively attributed to the spin-dependent conductivity of the magnetic graphene resulting from the proximity of an interlayer antiferromagnet, chromium sulfide bromide (CrSBr). We clearly demonstrate that the usage of the conventional air-sensitive 3D magnetic contacts can be fully avoided when graphene/CrSBr heterostructures are employed. Moreover, apart from providing exceptionally long spin relaxation length, the usage of graphene for both generation and transport of the spin allows to automatically avoid the conductivity mismatch between the source and the channel circuits that has to be considered when using conventional low-resistive contacts. Our results address a necessary step in the engineering of spintronic circuitry out of layered materials and precede further developments in the area of complex spin-logic devices. Moreover, we introduce a fabrication procedure where we designed and implemented a recipe for the preparation of electrodes via a damage-free technique that offers an immediate advantage in the fields of air-sensitive and delicate organic materials.

Crystalline porous ionic salts assembled from polyoxometalates and cationic capsule for the selective photocatalytic aerobic oxidation of aromatic alcohols to aldehydes

Crystalline porous ionic salts (CPISs) represent a new type of porous materials constructed by electrostatic interaction, however, synthesis of CPISs bearing pre-designed functionality while exhibiting permanent porosity is still challenging. Herein we report the facile synthesis of a series of CPISs 1-3 built from photocatalytic-active polyoxometalate (POM) clusters and cationic Zr-based capsules, which showed open porous frameworks with BET surface area up to 33 m2/g and high activity and selectivity for photo-driven aerobic oxidation of alcohols to aldehydes. Compared with the pristine POM cluster {W10}, 1 can promote the reaction in much higher efficiency due to the concerted catalysis of preinstalled {W10} and Zr-based capsule together with open channels. This work highlights the advantage of CPISs as porous heterogeneous catalysts in organic transformation, and may shed light on the rational design of more delicate CPISs-derived functional materials.

Gentle Patterning Approaches toward Compatibility with Bio-Organic Materials and Their Environmental Aspects.

Advances in material science, bioelectronic, and implantable medicine combined with recent requests for eco-friendly materials and technologies inevitably formulate new challenges for nano- and micropatterning techniques. Overall, the importance of creating micro- and nanostructures is motivated by a large manifold of fundamental and applied properties accessible only at the nanoscale. Lithography is a crucial family of fabrication methods to create prototypes and produce devices on an industrial scale. The pure trend in the miniaturization of critical electronic semiconducting components has been recently enhanced by implementing bio-organic systems in electronics. So far, significant efforts have been made to find novel lithographic approaches and develop old ones to reach compatibility with delicate bio-organic systems and minimize the impact on the environment. Herein, such delicate materials and sophisticated patterning techniques are briefly reviewed.

Etchless pedestal chalcogenide waveguide platform for long-wave IR applications

We report the fabrication of GeAsSeTe/GeAsSe waveguides using a simple and cost-effective process. Chalcogenides are very delicate materials and can be degraded when in contact with developer solutions during photolithography and when processed using common etchants, making the use of conventional fabrication processes unattractive. In order to avoid any post-film deposition processing for the fabrication of chalcogenide waveguides, we pre-patterned pedestal structures on silicon substrates using photolithography and a simple wet-etch process followed by the deposition of chalcogenide films on the patterned structures. Using the scattered light decay fitting method, we estimated waveguide propagation losses averaging approximately 0.9 dB/cm for wavelengths between 7 and 11 µm. With these findings we show that this waveguide platform is a very attractive candidate for long-wave infrared applications.

Design and Testing of a Piezoelectric Linear Micro-Displacement Actuator

To realize precision drive and control in actuators, a piezoelectrically driven linear micro-displacement actuator was designed in this paper. The structure of the actuator was designed, and the working mechanism of the micro-displacement actuator was analyzed. In addition, the theoretical and simulation analyses of the micro-displacement actuator were performed by establishing the system dynamics model, and the factors that influence the performance of the micro-displacement actuator were obtained. Finally, prototypes were produced, and the micro-displacement drive was tested to examine the influence of driving voltage, driving frequency, and load on the displacement and speed of the drive. The results indicate that the platform movement speed decreases with increasing load, and the maximum movement speed is 3.45 mm/s when the driving voltage and driving frequency are 150 V and 237.8 Hz, respectively. The actuator designed in this paper is suitable for driving small and delicate materials and platforms.