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The objective of this study is to compare and assess the effectiveness of real-time polymerase chain reaction (RT-PCR), loop-mediated isothermal amplification (LAMP), and the selective agar plate method for the detection of Salmonella spp. and Listeria monocytogenes in ready-to-eat (RTE) foods. In RTE foods, the detection performance of the three methods (RT-PCR [SureTectTM kit and PowerChekTM kit], LAMP [3M MDS], selective agar) were similar at 0-10, 10-50, 50-100, and 100- CFU/mL of Salmonella spp. and L. monocytogenes. We found that with RT-PCR, the Ct value of salad was significantly higher (p

Atomic layer deposition of MoS2 reveals stepwise growth – ‘stop and go’ growth of MoS2 – behavior where the surface migration energy of the adsorbates is significantly enhanced.

Atomic layer deposition (ALD) is a technique based on the surface reaction of precursors; thus, it strongly depends on the surface states of the substrate. We demonstrate significant changes in the structural and electrical properties of SnO thin films via modification of substrate surface states. The surface of SiO2 exposed to the atmosphere is usually contaminated by organic compounds and lacks hydroxyl groups. The plasma treatment effectively formed numerous functional groups on SiO2, eventually resulting in significant differences in the growth characteristics and properties of ALD-grown SnO films. In the case of a plasma-treated SiO2 substrate, the SnO layer was fully crystallized at the SnO/SiO2 interface, and the (00l) planes of SnO were aligned parallel to the substrate. The numerous functional groups on the plasma-treated SiO2 promoted a complete reaction on the surface, which resulted in the formation of more stoichiometric SnO containing fewer impurities near the interface. The changes in the interfacial properties by the plasma treatment of SiO2 enhanced the field-effect mobility from 0.7 to 2.0 cm2 V−1 s−1 and reduced the hysteresis voltage. The findings may contribute to the realization of complementary oxide thin film devices in future electronics.

Grain enlargement is a crucial requirement to synthesizing two-dimensional (2D) metal chalcogenides because it can minimize the effects of carrier scattering at the grain boundaries. To this end, r...

Gas sensors for Internet of Things applications should meet two requisites – low power consumption and easy mounting universally. To satisfy the conditions, gas sensors need to operate at lower temperature and be flexible. In this study, we demonstrate a flexible gas sensor operating at room temperature using vertically aligned two-dimensional SnS2 nanomaterials. The atomic layer deposition (ALD) technique allows direct growth of SnS2 on a plastic substrate. The morphological structure of SnS2 is engineered by effecting changes in the growth temperature and substrate surface, which leads to the excellent sensing performance with respect to NO2 gas along with superior gas selectivity. The gas response is as high as 309 at 1 ppm of NO2 at room temperature, and a reliably high response is also observed even below 500 ppb of NO2. The fabricated flexible gas sensor exhibits comparable sensing performance and stability upon bending. Furthermore, the ALD achieves excellent uniformity in both the structural and electrical properties of SnS2 over a 4 in. wafer, which is essential for mass production. Therefore, we believe that this work would contribute to realizing the practical application of highly sensitive flexible gas sensors.

Salmonella is the leading cause of zoonotic foodborne illnesses worldwide and a prevalent threat to the poultry industry. For controlling contamination, the use of chemical sanitizers in combination with biological compounds (e.g., enzymes) offers a solution to reduce the chemical residues. The current study investigated the biofilm reduction effects of a food-grade enzyme-ficin-and a common sanitizer-peroxyacetic acid (PAA)-against an emerging pathogen, Salmonella enterica ser. Thompson, on plastic, eggshell, and chicken skin surfaces. Results showed that PAA could kill S. Thompson, but ficin cannot. Maximum biofilm reduction was 3.7 log CFU/cm

Black phosphorus (BP) has shown great potential as a semiconductor material beyond graphene and MoS2 because of its intrinsic band gap and high mobility. Moreover, the biocompatibility of the final biodegradation products of BP has led to extensive research on biomedical applications. Herein, physically transient field-effect transistors (FETs) based on black phosphorus have been demonstrated using peptide insulator as a gate dielectric layer. The fabricated devices show high hole mobility up to 468 cm2 V–1 s–1 and on–off current ratio over 103. The combined use of black phosphorus, peptide, and molybdenum provides rapid disappearance of the devices within 36 h. Dissolution kinetics and cytotoxicity of black phosphorus are assessed to clarify its availability to be applied in transient electronics. This work provides transient FETs with high degradability and high performance based on biocompatible black phosphorus.

As a means to overcome the limitation of installation space and to promote the utilization of the solar cell in various applications, a transparent thin-film solar cell has been studied by many researchers. To achieve a transparent solar cell, the choice of materials which are transparent enough and showing the photovoltaic property at the same time is the key. Here, we suggest a two-dimensional (2D) p–n heterojunction of WSe2/MoS2 and an indium tin oxide electrode to fabricate a transparent thin-film photovoltaic cell. Because of advantages that 2D materials possess, a highly transparent (∼80%) solar cell with considerable efficiency was achieved. Furthermore, by introducing a transparent passivation layer composed of a fluoropolymer, the photovoltaic performance was much improved. With the passivation layer, our WSe2/MoS2 transparent photovoltaic cell reached an efficiency of ∼10%. A comparison of photovoltaic parameters before and after applying passivation and analysis on the origin of such difference...

Two-dimensional (2D) materials are known for their unique properties and potential for application in various electronic and optoelectronic devices. Since 2D semiconductors have weak bonding between the layers, they can be easily separated into several nanometer-thick layers which still maintain their characteristics. GaTe is a p-type 2D semiconductor having a direct bandgap. By combining multi-layer GaTe and thin-film IGZO, we have fabricated a p–n heterojunction, a fundamental unit of optoelectronic devices. In this paper, we propose the first fully transparent solar cell using a 2D material, based on a GaTe/IGZO heterostructure. The device shows a high transparency of ∼90% and an efficiency of 0.73% with a fill factor of 37%. It exhibits instantaneous generation of photo-carriers under periodic light pulses. Further analysis of the operating mechanism was conducted by studying its band alignments. The transparency of our GaTe/IGZO solar cell can overcome its relatively low efficiency, as it can be installed in a much larger scale and the total amount of generated power will surpass that of the conventional solar cell. Furthermore, advances in the large-scale growth of GaTe will enhance the power conversion efficiency, and finally enable the adoption of 2D active layer based highly transparent, thin-film solar cells for building integrated photovoltaic systems.

As a means to overcome the limitation of installation space and to promote the utilization of the solar cell in various applications, a transparent thin-film solar cell has been studied by many researchers. To achieve a transparent solar cell, the choice of materials which are transparent enough and showing the photovoltaic property at the same time is the key. Here, we suggest a two-dimensional (2D) p-n heterojunction of WSe

The speed of integrated circuits has become one of the key technical concerns in order to be able to improve the performance of microelectronics devices. A complex device structure and high cost process technology are required in order to increase the clock speed of a functional circuit built with conventional Sifield effect transistors (FETs), and the low electron mobility of amorphous Si (∼ 1c m 2 /V s) is undesirable for some applications in large area electronics. For example, the low mobility is a bottleneck that prevents fabricating active matrix liquid crystal displays (AMLCD) with high resolutions and high driving speeds. 1 Two-dimensionalmaterials,suchasgraphene,maybeabletoovercome some of the shortcomings presented by Si materials. Graphene has mobility on the order of 10,000 cm 2 /V ·s, but another property inherent to graphene is its zero band-gap, which introduces many technical challenges to realize reliable, high-performance devices. 2 Semiconducting transitional metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS2), are two-dimensional materials similar to graphene, and they are considered to be potential replacement for amorphous Si. In MoS2, Mo and S atoms are strongly bonded with covalent bonds within each layer, while interlayer bonding is maintained via weak Van der Waals interactions. 3 In addition, MoS2 has a sizable band-gap, with an indirect band-gap of 1.2 eV for bulk material and a direct band-gap of 1.8 eV for a single-layer configuration. 3 This property of MoS2 leads to a low off-current when a MoS2 FET is fabricated. 4

Two-dimensional materials have recently been spotlighted, due to their unique properties in comparison with conventional bulk and thin-film materials. Among those materials, MoS2 is one of the promising candidates for the active layer of electronic devices because it shows high electron mobility and pristine band gap. In this paper, we focus on the evolution of the electrical property of the MoS2 field-effect transistor (FET) as a function of post-annealing temperature. The results indicate that the off current drastically decreased at 200°C and increased at 400°C while other factors, such as the mobility and threshold voltage, show little variation. We consider that the decreasing off current comes from the rearrangement of the MoS2 film and the elimination of the surface residue. Then, the increasing off current was caused by the change of the material's composition and adsorption of H2O and O2. Electronic supplementary material The online version of this article (doi:10.1186/s11671-015-0773-y) contains supplementary material, which is available to authorized users.

For several years, graphene has been the focus of much attention due to its peculiar characteristics, and it is now considered to be a representative 2-dimensional (2D) material. Even though many research groups have studied on the graphene, its intrinsic nature of a zero band-gap, limits its use in practical applications, particularly in logic circuits. Recently, transition metal dichalcogenides (TMDs), which are another type of 2D material, have drawn attention due to the advantage of having a sizable band-gap and a high mobility. Here, we report on the design of a complementary inverter, one of the most basic logic elements, which is based on a MoS2 n-type transistor and a WSe2 p-type transistor. The advantages provided by the complementary metal-oxide-semiconductor (CMOS) configuration and the high-performance TMD channels allow us to fabricate a TMD complementary inverter that has a high-gain of 13.7. This work demonstrates the operation of the MoS2 n-FET and WSe2 p-FET on the same substrate, and the electrical performance of the CMOS inverter, which is based on a different driving current, is also measured.