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Diacetyl (C4H6O2) is an important organic diketone that is widely used as flavoring agent and food additive. It is toxic when inhaled or exposed to high concentrations and may lead to chronic respiratory disease and neurodegenerative disorders. But, a viable optical detection method for rapid and quantitative estimation of diacetyl molecules in gas phase does not currently exist. Here, we report the design and development of a simple, compact and cost-effective robust optical technique exploiting incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) technique for high-sensitive selective detection and quantitative estimation of gas-phase diacetyl levels in real-time using a visible light emitting diode (LED) operating at 450 nm. The IBBCEAS method demonstrates an effective optical-path length of 4.5 km within an optical cavity (Finesse ~15706) composed of two high-reflective mirrors. A typical detection limit of ~190 parts-per-billion (ppb) for diacetyl was achieved with an optimum acquisition time of ~4 s at an optimal cavity pressure of 100 Torr. LED-based diacetyl sensor system was optimized, calibrated and demonstrated for trace detection of gaseous diacetyl at the ppb levels in various food products and liquor samples as a few representative applications, thus paving the way for development of future optical monitors. This work represents the development of a LED-based optical setup for the detection of diacetyl molecule in gas phase. [ABSTRACT FROM AUTHOR]

Biochar-based composite phase change materials (PCMs) are gaining popularity in thermal energy storage (TES) applications. Organic PCMs derived from fatty acids are favored for their affordability and variable melting temperatures based on carbon chain length. Understanding the interaction between different carbon-length fatty acid PCMs and porous biochar is crucial for optimizing thermal performance. Thus, this study explored the interaction between PCMs of decanoic acid (DA) and octadecanoic acid (OA) with banana peel (BP) biochar. Experimental results showed that shorter carbon chain of DA enhanced thermal properties and surface compactness compared to OA. BP-DA had higher loading efficiency and PCMs ratio, resulting in superior thermal cycle endurance and latent heat ratio. The molecular dynamics suggest that longer carbon chains affect the mean square displacement (MSD) curves, reducing the self-diffusion coefficients of BP-DA. This is due to DA's high loading rate, which occupies more space within BP biochar structure, thus limiting its diffusion capacity. Enhanced hydrogen bonding constrained DA's thermal motion during phase transition, restricting atom mobility within BP. With temperature elevations, BP-DA exhibits lesser fractional free volume than BP-OA, due to lower molecular mass. This research highlights how carbon chain length influences composite PCMs performance, offering insights for efficient TES system design. [ABSTRACT FROM AUTHOR]

Lauric acid (LA) has been recommended as economic, eco-friendly, and commercially viable materials to be used as phase change materials (PCMs). Nevertheless, there is lack of optimized parameters to produce microencapsulated PCMs with good performance. In this study, different amounts of LA have been chosen as core materials while tetraethyl orthosilicate (TEOS) as the precursor solution to form silicon dioxide (SiO2) shell. The pH of precursor solution was kept at 2.5 for all composition of microencapsulated LA. The synthesized microencapsulated LA/SiO2 has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The SEM and TEM confirm the microencapsulation of LA with SiO2. Thermogravimetric analysis (TGA) revealed better thermal stability of microencapsulated LA/SiO2 compared to pure LA. PCM with 50% LA i.e. LAPC-6 exhibited the highest encapsulation efficiency (96.50%) and encapsulation ratio (96.15%) through Differential scanning calorimetry (DSC) as well as good thermal reliability even after 30th cycle of heating and cooling process. [ABSTRACT FROM AUTHOR]

Amorphous structures of the as-cast bulk metallic glass samples (BMGs) of Cu60Zr25Ti15 and (Cu60Zr25Ti15)95Ni5 alloys are confirmed by X-ray diffraction. Isothermal crystallization kinetics of these BMGs are investigated using differential scanning calorimetry. For both the alloys, the apparent activation energy (Ea) shows a strong dependency on crystallization volume fraction (x). Isothermal crystallization kinetic parameters are calculated by Arrhenius and Johnson–Mehl–Avrami equations. Avrami exponential factor (n) is also found to show clear correlation with the crystallization volume fraction (x). It is found that the crystallization process is easier in Cu60Zr25Ti15 BMG than in (Cu60Zr25Ti15)95Ni5 BMG as the Ea decreases constantly for the former alloy though in the case of second alloy, the Ea is almost unchanged up to x = 60%. For both the alloys, nucleation activation energy (Enucleation) is found to be higher than that of growth activation energy (Egrowth). This indicates that the growth of crystals during isothermal crystallization in these glasses is easier than nucleation, and the minor addition of Ni causes the higher thermal stability against crystallization in isothermal condition. [ABSTRACT FROM AUTHOR]

This paper reports the crystallization kinetics of (Cu60Zr25Ti15)99.3Nb0.7 bulk metallic glass under isothermal conditions. Differential scanning calorimetry (DSC) has been employed for isothermal annealing at ten different temperatures prior to the onset of crystallization (To) temperature. X-ray diffraction and transmission electron microscopy have been used to confirm the amorphous structure of the as cast sample. Crystallized volume fractions (x) are calculated from the exothermic peaks of DSC scans. Crystallized volume fractions (x) against time show sigmoidal type of curves as well as the curves become steeper at higher annealing temperatures. Continuous heating transformation diagram has been simulated to understand the stability of the bulk metallic glass. Crystallization kinetics parameters are calculated using Arrhenius and Johnson–Mehl–Avrami equations. Activation energy (Ea) and Avrami exponential factor (n) have exhibited strong correlation with crystallized volume fraction (x). The average activation energy for isothermal crystallization is found to be 330 ± 30 kJ/mol by Arrhenius equation. Nucleation activation energy (Enucleation) is found to be higher than that of growth activation energy (Egrowth). The Avrami exponential factor (n) indicates about the diffusion controlled mechanism of the nucleation and three-dimensional growth. [ABSTRACT FROM AUTHOR]

This paper reports the changes in the electrochemical behavior of Cu60Zr25Ti15 bulk metallic glass (BMG) with the addition of 1 at.% Mo and Nb in 3.5 wt.% NaCl aqueous solution. Electrochemical methods employed for the study are open-circuit potential (OCP) and potentiodynamic polarization. The OCP values of the parent BMG and minor-alloyed BMGs differ only marginally. However, potentiodynamic studies show slightly higher corrosion resistance for the minor-alloyed BMGs than that of the parent alloy. Polarized surfaces of all the samples, examined under a scanning electron microscope (SEM), reveal pits formed due to corrosion. Corrosion products are analyzed by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Higher corrosion resistance observed for Nb- or Mo-added BMGs is attributed to the formation of NbO2/Nb2O5 and MoO2, respectively, besides the oxides of other constituent elements. [ABSTRACT FROM AUTHOR]

In this chapter the chemical mechanical polishing of nanocrystalline diamond film is presented. It is shown that it is possible to polish a superhard material like nanocrystalline diamond with a much softer material like silica. It has also been demonstrated that this technique can be used for removing polishing marks on single crystal diamond. Experiments with other oxides like ceria and alumina showed polishing action on nanocrystalline diamond films. Surface roughness reduction rate was found to be inversely proportional to the size of abrasive material. Addition of redox agents to the polishing slurry accelerated the roughness reduction of nanocrystalline diamond films. Based on the experimental results and theoretical studies by other groups we have proposed a polishing mechanism for chemical mechanical polishing of diamond. Lastly, we have applied this technique to study its effect on superconducting diamond films. It was found that even after 14 h of polishing, superconductivity in diamond remained unchanged. [ABSTRACT FROM AUTHOR]

Inadequate room-temperature plasticity limits the application of bulk metallic glasses (BMGs). This study focuses on enhancing the plasticity of BMGs for widening their applications. Composition modification of Cu60Zr25Ti15 through the minor addition of Ni is the approach adopted in this study. A systematic increase in mechanical properties is observed with increasing Ni content (up to 5 at. pct), followed by a decrease thereafter. Values of yield stress (2425 MPa), fracture stress (2513 MPa), maximum stress (2725 MPa), and plastic strain (16 pct) exhibited by (Cu60Zr25Ti15)95Ni5 BMGs are higher than those reported in the literature for Cu-BMGs (high Cu content). Analysis of the glass transition region indicated that the enthalpy values of the exothermic heat flow prior to glass transition (ΔHbg) and the fragility parameter (m) are well correlated with the plasticity of the alloys. The increasing fragility parameter and exothermic enthalpy correspond to higher free volume. Therefore, high plasticity values can be attributed to the free volume modification (creation and distribution) caused by Ni addition. This free volume modification initiates shear bands and promotes their branching; consequent interactions among them increase the resistance to shear band propagation and, thereby, delay the fracture. [ABSTRACT FROM AUTHOR]

Nanoparticle-based flexible field-effect transistors (FETs) containing carbon nanotubes (CNTs) and silicon nanowires (SiNWs) have attracted tremendous attention, since their interesting device performance can be utilized for integrated nanoscale electronics. However, use of CNTs and SiNWs on polymer substrates poses serious limitations in terms of their fabrication procedure, repeatability, and biodegradability. In this article, we report for the first time the fabrication and characteristics of solution-processed FETs on a paper substrate doped with easily prepared silver nanoparticles (AgNPs). To compare the FET performance, we fabricated two other FETs on paper containing ionic liquid (IL, 1-butyl-3-methylimidazolium octyl sulfate) and reduced graphene oxide (rGO) as dopants. We observe that the AgNP-based dopant generated good FET characteristics in terms of linear transconductance variations and higher carrier concentration values, showing negligible changes after bending and aging. In comparison with the AgNP-FET, the rGO- and IL-based dopants yielded high carrier mobilities, but the rGO-based FET is more susceptible to aging and bending. The excellent linearity of the I- V curve found for the AgNP-FET ensures its applicability for devices requiring linear transfer characteristics such as linear amplifiers. [ABSTRACT FROM AUTHOR]

Trajectory corners generated while generation of a curve from curved fragments using micro-positioning $$X{-}Y$$ stages poses serious limitations on their use for smooth motion trajectory applications. In this research, a controller along with its control algorithm is presented which uses a penalized curve fitting-based approach to steer low cost/ low resolution stepper motor driven stage motion so that the cornerization in the trajectory is minimized without any serious degradation to accuracy. The control algorithm is initially implemented in MATLAB to check its fidelity. Subsequently, a complete set up involving ARM-based controller, motor drivers and precision positioning stages is built in order to facilitate the working of the algorithm in real time. The set up is tested for CNC machining application, where material removal takes place in a precise manner according to the trajectory of $$X{-}Y$$ positioning stages. A good match was found between simulation and experimental results in trajectory generation. It was further observed that the use of penalized spline trajectory reduces the cornerization in trajectory generation. [ABSTRACT FROM AUTHOR]

Micro precision X-Y stages have several applications in industry ranging from metal machining to positioning of optical instruments. This paper deals with the evaluation of relationship between jerk in micro precision stages and harmonics in voltage of the motor by which the stage is driven and subsequently proposes an algorithm on Arduino Mega micro controller board to reduce the jerk by shaping the velocity profile while varying the microstepping rate in motor voltage. A micro precision stage with a resolution of 1 micron, driven with a bipolar stepper motor drive is used to evaluate the algorithm. A MEMS accelerometer (ADXL 345) is placed rigidly on the stage, and the acceleration at varying speeds is measured and logged in the micro controller. The micro controller sends commands to the motor driver (L6470 driver) for driving the motor using Serial Peripheral interface. The motor driver is configured in microstepping mode. Experiments confirm the fact that there is a strong correlation between jerk in micropositioning stage and motor supply voltage harmonics. A methodology to reduce the jerk has also been facilitated. This involves use of microstepping mode in stepper motor driver with dynamic sliding in microstepping rate. A threshold value of jerk is considered and based on that, the microstepping rate is varied which subsequently reduces voltage harmonics. Reduction in voltage harmonics reduces the jerk in the stage. Maximum jerk reduction of 97.3 % was achieved in the process. [ABSTRACT FROM AUTHOR]

Micro-nano patterned surfaces possess unique adhesion, wetting and dewetting properties, prompting their growing applications ranging from water repellant windshields of automobiles, antibacterial surfaces of medical devices to algae cultivation for biodiesel generation. The current need is manufacturing systems and processing protocols to create highly controlled patterns directly on solid substrates over large area. In this paper, a pantograph-based desktop micro machine has been designed to create micro-nano scale patterns over 25 mm × 25 mm area directly over solid surfaces by nano-scratching/scribing process. It is designed to achieve precision positioning of scratching tool (tip) and to retain its orientation such that effective rake angle remains unaltered, unlike in atomic force microscopy based scratching techniques. The design of the mechanism and micro-motion analysis achieved by integrating unique design for revolute joints are described. The machine performance in generating micro-patterns over copper and aluminium substrates has been studied. [ABSTRACT FROM AUTHOR]

The angle dependent magnetoresistance study on [001] and [110] LaSrMnO thin films shows that the anisotropy energy of [110] films is higher than that of a [001] oriented LaSrMnO film of similar thickness. The data have been analyzed in the light of a multidomain model and it is seen that this model correctly explains the observed behavior. [ABSTRACT FROM AUTHOR]

Stearic acid (SA) is being used as phase change material (PCM) in energy storage applications. In the present study, the microencapsulation of SA with SiO2 shell was carried out by sol–gel method. Different amounts of SA (5, 10, 15, 20, 30 and 50 g) were taken against 10 ml of tetraethyl orthosilicate (TEOS) for encapsulation. The synthesized microencapsulated PCM (MEPCM) were characterized by Fourier transform infrared spectroscope (FT-IR), X-Ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The characterization results showed that SA was successfully encapsulated by SiO2. Thermogravimetric analysis (TGA) exhibited better thermal stability of the MEPCM than SA. The enthalpy values of MEPCM were found to be unchanged even after 30 heating–cooling cycles by differential scanning calorimetry (DSC). The latent heats of melting and solidification of 50 g SA containing MEPCM were found to be highest i.e. 182.53 J/g and 160.12 J/g, respectively among all microencapsulated samples. The encapsulation efficiency values were calculated using thermal data and the efficiency was found to be highest i.e. 86.68% in the same sample. [ABSTRACT FROM AUTHOR]

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper. [ABSTRACT FROM AUTHOR]

2D MXene has attracted much attention in electrochemical blood glucose sensing technology in the recent past. However, the use of MXene as an electrochemical sensor material has exhibited limitations as the output signal in the form of current remained weak to express the sensitivity, which has been a critical factor for the fabrication of a new sensor under the point-of-care (PoC) settings. To address this issue, a 3D-printed nickel metal–organic frameworks-MXene (NiMOF-MXene) nanocomposite-based PoC sensing chip has been reported for electrochemical detection of blood glucose at physiological pH. The synthesized nanocomposite (NiMOF-MXene) was mixed with carbon black (CB) ink and sequentially 3D printed as NiMOF-MXene@CB-layered electrode structure, where NiMOF acted as active interfacial sites for glucose oxidation, MXene mediated the rapid electron transfer and CB acted as the binder for nanocomposite-based ink. The estimated limit of detection, sensitivity, and linear range of the fabricated sensor was found to be 0.5 µM, 3.90 mA mM−1 cm−2, and 1–15 mM, respectively. The sensor was tested for its glucose detection capability using whole blood samples. Compared to the recently reported chip-based electrochemical blood glucose sensors, this sensor does not require blood dilution with alkaline media establishing its electrochemical capability toward human blood glucose detection under PoC settings.Graphical abstract: 2D MXene has attracted much attention in electrochemical blood glucose sensing technology in the recent past. However, the use of MXene as an electrochemical sensor material has exhibited limitations as the output signal in the form of current remained weak to express the sensitivity, which has been a critical factor for the fabrication of a new sensor under the point-of-care (PoC) settings. To address this issue, a 3D-printed nickel metal–organic frameworks-MXene (NiMOF-MXene) nanocomposite-based PoC sensing chip has been reported for electrochemical detection of blood glucose at physiological pH. The synthesized nanocomposite (NiMOF-MXene) was mixed with carbon black (CB) ink and sequentially 3D printed as NiMOF-MXene@CB-layered electrode structure, where NiMOF acted as active interfacial sites for glucose oxidation, MXene mediated the rapid electron transfer and CB acted as the binder for nanocomposite-based ink. The estimated limit of detection, sensitivity, and linear range of the fabricated sensor was found to be 0.5 µM, 3.90 mA mM−1 cm−2, and 1–15 mM, respectively. The sensor was tested for its glucose detection capability using whole blood samples. Compared to the recently reported chip-based electrochemical blood glucose sensors, this sensor does not require blood dilution with alkaline media establishing its electrochemical capability toward human blood glucose detection under PoC settings. [ABSTRACT FROM AUTHOR]