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We demonstrate a magnetocaloric ferrofluid based on a gadolinium saturated liquid metal matrix, using a gallium-based liquid metal alloy as the solvent and suspension medium. The material is liquid at room temperature, while exhibiting spontaneous magnetization and a large magnetocaloric effect. The magnetic properties were attributed to the formation of gadolinium nanoparticles suspended within the liquid gallium alloy, which acts as a reaction solvent during the nanoparticle synthesis. High nanoparticle weight fractions exceeding 2% could be suspended within the liquid metal matrix. The liquid metal ferrofluid shows promise for magnetocaloric cooling due to its high thermal conductivity and its liquid nature. Magnetic and thermoanalytic characterizations reveal that the developed material remains liquid within the temperature window required for domestic refrigeration purposes, which enables future fluidic magnetocaloric devices. Additionally, the observed formation of nanometer-sized metallic particles within the supersaturated liquid metal solution has general implications for chemical synthesis and provides a new synthetic pathway toward metallic nanoparticles based on highly reactive rare earth metals. [ABSTRACT FROM AUTHOR]

Planar 2D materials are possibly the ideal channel candidates for future field effect transistors (FETs), due to their unique electronic properties. However, the performance of FETs based on 2D materials is yet to exceed those of conventional silicon based devices. Here, a 2D channel thin film made from liquid phase exfoliated molybdenum oxide nanoflake inks with highly controllable substoichiometric levels is presented. The ability to induce oxygen vacancies by solar light irradiation in an aqueous environment allows the tuning of electronic properties in 2D substoichiometric molybdenum oxides (MoO3− x). The highest mobility is found to be ≈600 cm2 V−1 s−1 with an estimated free electron concentration of ≈1.6 × 1021 cm−3 and an optimal IOn/ IOff ratio of >105 for the FETs made of 2D flakes irradiated for 30 min ( x = 0.042). These values are significant and represent a real opportunity to realize the next generation of tunable electronic devices using electronic inks. [ABSTRACT FROM AUTHOR]

Quasi-two-dimensional(quasi-2D) molybdenum disulfide (MoS2) is a photoluminescence(PL) material with unique properties.The recent demonstration of its PL, controlled by the intercalationof positive ions, can lead to many opportunities for employing thisquasi-2D material in ion-related biological applications. Here, wepresent two representative models of biological systems that incorporatethe ion-controlled PL of quasi-2D MoS2nanoflakes. Theion exchange behaviors of these two models are investigated to revealenzymatic activities and cell viabilities. While the ion intercalationof MoS2in enzymatic activities is enabled via an externalapplied voltage, the intercalation of ions in cell viability investigationsoccurs in the presence of the intrinsic cell membrane potential. [ABSTRACT FROM AUTHOR]

Abstract: For understanding cells functionalities and their communications, there is a need for highly sensitive cell analysis platforms capable of assessing non-specific chemicals on the surface and in the vicinity of cells. We report a microfluidic system integrating dielectrophoresis and surface enhanced Raman scattering (SERS) for the trapping and real time monitoring of cell functions in isolated and grouped cell clusters. Yeast cells are coated with silver nanoparticles to enable highly sensitive SERS analysis. The SERS responses of cells are examined under various conditions: live vs. dead and isolated vs. grouped. This work illustrates the feasibility of the system for in situ cell monitoring and analysis of secreted chemicals during their growth, metabolism, proliferation and apoptosis. [Copyright &y& Elsevier]

Raman microscopy systems are becoming increasingly widespread and accessible for characterising chemical species. Microfluidic systems are also progressively finding their way into real world applications. Therefore, it is anticipated that the integration of Raman systems with microfluidics will become increasingly attractive and practical. This review aims to provide an overview of Raman microscopy-microfluidics integrated systems for researchers who are actively interested in utilising these tools. The fundamental principles and application strengths of Raman microscopy are discussed in the context of microfluidics. Various configurations of microfluidics that incorporate Raman microscopy methods are presented, with applications highlighted. Data analysis methods are discussed, with a focus on assisting the interpretation of Raman-microfluidics data from complex samples. Finally, possible future directions of Raman-microfluidic systems are presented. [ABSTRACT FROM AUTHOR]

We demonstrate an active microfluidic platform that integrates dielectrophoresis for the control of silver nanoparticles spacing, as they flow in a liquid channel. By careful control of the nanoparticles spacing, we can effectively increase the surface-enhanced Raman scattering (SERS) signal intensity based on augmenting the number of SERS-active hot-spots, while avoiding irreversible aggregation of the particles. The system is benchmarked using dipicolinate (2,6-pyridinedicarboxylic acid) (DPA), which is a biomarker of Bacillus anthracis. The validity of the results is discussed using several complementing characterization scenarios. [ABSTRACT FROM AUTHOR]

Summary: Background: Carbohydrate fermentation plays a pivotal role in maintaining colonic health with excessive proximal and deficient distal fermentation being detrimental. Aims: To utilise telemetric gas‐ and pH‐sensing capsule technologies for defining patterns of regional fermentation following dietary manipulations, alongside conventional techniques of measuring fermentation. Methods: In a double‐blind crossover trial, 20 patients with irritable bowel syndrome were fed low FODMAP diets that included no extra fibre (total fibre content 24 g/day), or additional poorly fermented fibre, alone (33 g/day) or with fermentable fibre (45 g/day) for 2 weeks. Plasma and faecal biochemistry, luminal profiles defined by tandem gas‐ and pH‐sensing capsules, and faecal microbiota were assessed. Results: Plasma short‐chain fatty acid (SCFA) concentrations (μmol/L) were median (IQR) 121 (100–222) with fibre combination compared with 66 (44–120) with poorly fermented fibre alone (p = 0.028) and 74 (55–125) control (p = 0.069), but no differences in faecal content were observed. Luminal hydrogen concentrations (%), but not pH, were higher in distal colon (mean 4.9 [95% CI: 2.2–7.5]) with fibre combination compared with 1.8 (0.8–2.8) with poorly fermented fibre alone (p = 0.003) and 1.9 (0.7–3.1) control (p = 0.003). Relative abundances of saccharolytic fermentative bacteria were generally higher in association with supplementation with the fibre combination. Conclusions: A modest increase in fermentable plus poorly fermented fibres had minor effects on faecal measures of fermentation, despite increases in plasma SCFA and abundance of fermentative bacteria, but the gas‐sensing capsule, not pH‐sensing capsule, detected the anticipated propagation of fermentation distally in the colon. The gas‐sensing capsule technology provides unique insights into localisation of colonic fermentation. Trial registration: ACTRN12619000691145. [ABSTRACT FROM AUTHOR]

Abstract: Plasmonic biosensors based on noble metals generally suffer from low sensitivities if the perturbation of refractive‐index in the ambient is not significant. By contrast, the features of degenerately doped semiconductors offer new dimensions for plasmonic biosensing, by allowing charge‐based detection. Here, this concept is demonstrated in plasmonic hydrogen doped molybdenum oxides (HxMoO3), with the morphology of 2D nanodisks, using a representative enzymatic glucose sensing model. Based on the ultrahigh capacity of the molybdenum oxide nanodisks for accommodating H+, the plasmon resonance wavelengths of HxMoO3 are shifted into visible‐near‐infrared wavelengths. These plasmonic features alter significantly as a function of the intercalated H+ concentration. The facile H+ deintercalation out of HxMoO3 provides an exceptional sensitivity and fast kinetics to charge perturbations during enzymatic oxidation. The optimum sensing response is found at H1.55MoO3, achieving a detection limit of 2 × 10−9 m at 410 nm, even when the biosensing platform is adapted into a light‐emitting diode‐photodetector setup. The performance is superior in comparison to all previously reported plasmonic enzymatic glucose sensors, providing a great opportunity in developing high performance biosensors. [ABSTRACT FROM AUTHOR]

Review: 295 refs. [ABSTRACT FROM AUTHOR]

Summary: Background: Accurate definition of the gastroduodenal and ileocaecal junctions (GDJ, ICJ) is essential for the measurement of regional transit times. Aims: To compare the assessment of these landmarks using the novel gas‐sensing capsule and validated wireless motility capsule (WMC), and to evaluate intra‐subject variance in transit times Methods: Healthy subjects ingested the gas‐sensing capsule and WMC tandemly in random order. Inter‐observer agreement was evaluated by intra‐class correlation coefficient (ICC). Agreement between the paired devices' transit times was assessed using Bland–Altman analysis; coefficient of variation was performed to express intra‐individual variance in transit times. Similar analyses were completed with tandemly ingested gas‐sensing capsules. Results: The inter‐observer agreement for landmarks for both capsules was excellent (mean ICC ≥0.97) in 50 studies. The GDJ was identifiable in 92% of the gas‐sensing capsule studies versus 82% of the WMC studies (p = 0.27); the ICJ in 96% versus 84%, respectively (p = 0.11). In the primary cohort (n = 26), median regional transit times differed by less than 6 min between paired capsules. Bland–Altman revealed a bias of −0.12 (95% limits of agreement, −0.94 to 0.70) hours for GDJ and − 0.446 (−2.86 to 2.0) hours for ICJ. Similar results were found in a demographically distinct validation cohort (n = 24). For tandemly ingested gas‐sensing capsules, coefficients of variation of transit times were 11%–35%, which were similar to variance between the paired gas‐sensing capsule and WMC, as were the biases. The capsules were well tolerated. Conclusions: Key anatomical landmarks are accurately identified with the gas‐sensing capsule in healthy individuals. Intra‐individual differences in transit times between capsules are probably due to physiological factors. Studies in populations with gastrointestinal diseases are now required. [ABSTRACT FROM AUTHOR]

By exploiting the very recent discovery of the piezoelectricity in odd-numbered layers of two-dimensional molybdenum disulfide (MoS2), we show the possibility of reversibly tuning the photoluminescence of single and odd-numbered multilayered MoS2 using high frequency sound wave coupling. We observe a strong quenching in the photoluminescence associated with the dissociation and spatial separation of electrons-holes quasi-particles at low applied acoustic powers. At the same applied powers, we note a relative preference for ionization of trions into excitons. This work also constitutes the first visual presentation of the surface displacement in one-layered MoS2 using laser Doppler vibrometry. Such observations are associated with the acoustically generated electric field arising from the piezoelectric nature of MoS2 for odd-numbered layers. At larger applied powers, the thermal effect dominates the behavior of the two-dimensional flakes. Altogether, the work reveals several key fundamentals governing acousto-optic properties of odd-layered MoS2 that can be implemented in future optical and electronic systems. [ABSTRACT FROM AUTHOR]

Liquid marbles are entities made of a small amount of liquid encapsulated by micro/nano scale particles. The functionality of liquid marbles depends on both the core liquid and particle coating. In this work, functional silver nanoparticle (Ag NPs)/oleic acid liquid marbles are developed using Ag NPs to encapsulate micro-sized oleic acid liquid spheres, which is achieved via sonication. We demonstrate that both the size of the encapsulated spheres and the order of the Ag NPs coating are a function of the sonication time. These micro-sized liquid marbles are investigated for sensing an organic thiolate as a model material. Their capacity for increasing solar light absorption and energy conversion into heat is also studied. The liquid marbles generated after sonication for 60 min show the strongest Raman peak signals which originate from the thiolate. They also demonstrate the highest solar energy absorption. We ascribe these enhancements to the increased surface area of the Ag NPs/oleic acid spheres and the optimum order of Ag NPs to produce the strongest surface enhanced Raman scattering. The liquid marbles can be used for the development of future biosensors and solar-thermal absorbers. [ABSTRACT FROM AUTHOR]

The exhibition of plasmon resonancesin two-dimensional (2D) semiconductorcompounds is desirable for many applications. Here, by electrochemicallyintercalating lithium into 2D molybdenum disulfide (MoS2) nanoflakes, plasmon resonances in the visible and near UV wavelengthranges are achieved. These plasmon resonances are controlled by thehigh doping level of the nanoflakes after the intercalation, producingtwo distinct resonance peak areas based on the crystal arrangements.The system is also benchmarked for biosensing using bovine serum albumin.This work provides a foundation for developing future 2D MoS2based biological and optical units. [ABSTRACT FROM AUTHOR]

The limitation of hot spot cooling in microchips represents an important hurdle for the electronics industry to overcome with coolers yet to exceed the efficiencies required. Nanotechnology-enabled heat sinks that can be magnetophoretically formed onto the hot spots within a microfluidic environment are presented. CrO2 nanoparticles, which are dynamically chained and docked onto the hot spots, establish tuneable high-aspect-ratio nanofins for the heat exchange between these hot spots and the liquid coolant. These nanofins can also be grown and released on demand, absorbing and releasing the heat from the hot spots into the microfluidic system. It is shown that both high aspect ratio and flexibility of the fins have a dramatic effect on increasing the heat sinking efficiency. The system has the potential to offer a practical cooling solution for future electronics. [ABSTRACT FROM AUTHOR]

Summary: Background: Intestinal gases are currently used for the diagnosis of disorders including small intestinal bacterial overgrowth and carbohydrate malabsorption. Aim: To compare the performance of measuring hydrogen production within the gut directly with the telemetric gas‐sensing capsule with that of indirect measurement through breath testing. Methods: Using standard breath testing protocols, the capsules and breath tests were simultaneously evaluated in a single‐blinded trial in 12 healthy subjects. Eight received a single dose of 1.25‐40 g inulin and four 20 or 40 g glucose. Safety and reliability of the capsules were also assessed. Results: There were no reported adverse events. All capsules were retrieved and operated without failure. Capsule measurements were in agreement with breath test measurements in magnitude but not in timing; minimal hydrogen production was observed after glucose ingestion and capsule measurements correlated with breath hydrogen after ingestion of 40 g inulin. A dose‐dependent increase in concentration of hydrogen was observed from the capsule following ingestion of inulin as low as 1.25 g compared with >10 g for breath measurements. Specifically, the capsule measured >3000 times higher concentrations of hydrogen compared to breath tests, resulting in a signal‐to‐noise ratio of 23.4 for the capsule compared to 4.2 for the breath test. Conclusions: The capsule showed high sensitivity and signal‐to‐noise ratio in measuring luminal hydrogen concentrations, provided information on the site of intestinal gas production, and demonstrated safety and reliability. The capsule has potential for improving diagnostic precision for disorders such as small intestinal bacterial overgrowth. [ABSTRACT FROM AUTHOR]