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The primary aim in the memory devices is to produce structures that exhibit two distinct states when a certain type of stimulus (e.g. electric field or magnetic field) is applied. These two states can be viewed as the realization of memory devices. It is to be noted that the class of memory devices that is discussed in this chapter is based on the admixture of small molecules, nanoparticles, and polymers; such devices are referred to as polymer electronic memory devices. This chapter captured the key developments that have happened in the field of organic memory devices for the last two decades. This chapters include discussions on the progress in this field and address challenges that scholars are currently faced with, such as questions about the mechanism(s) of bistability, the conundrum of the experimental data, and the contradictions prevalent among the different groups and future directions. The chapter also introduces reader some basic terms, concepts and terminology often used in this field.

Background: Hepatitis B virus (HBV) infection is one of the major causes of chronic liver disease which progresses from hepatitis to liver fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Early detection and laboratory based screening test of HCC is still a major challenge. HBV induces hepatocarcinogenesis through viral genome integration, chromosomal aberrations and modulation of host signaling pathways. Molecular alterations of cancer hallmark genes occur during the process of hepatocarcinogenesis. These signatures may release into the circulation through . circulating tumor DNA (ctDNA). Detection of these mutations in ctDNA may serve as liquid biopsy marker for screening, early detection and prognosis of HCC for which this study was undertaken. Methods: Consecutive patients of CHB-HCC (n=80), chronic hepatitis B (n=35) and healthy (n=15) controls were included for blood sample collection. The ctDNA was isolated from serum. Amplification and sequencing TP53 exon 7 and β-catenin exon 3 was carried out for predominant mutations in the ctDNA of HCC patients. Highly sensitive dual-probe based droplet digital PCR (ddPCR) assays were performed for TP53 (p.R249M & p.R249S) and β-catenin (p.S45P) driver mutations in healthy, CHB-noncirrhotic, cirrhotic and HCC patients. Results: Both TP53 gene exon 7 and CTNNB1 gene exon 3 region was amplified and sequenced in 32 HCC patient whereas sensitive ddPCR assay TP53 (p.R249M & p.R249S) and β-catenin (p.S45P) mutation for all 130 subjects. In sanger sequencing TP53 c.746 G˃T, p.R249M mutation was predominant. In ddPCR assay, 58.75% of HCC patients (n=47) ctDNA had at least one driver mutation in the ctDNA. Combined TP53 and CTNNB1 mutation was observed in 12.5% of HCC patients. Increased mutation frequency was observed in CHB-cirrhotic. CHB-HCC than CHB-noncirrhotic and healthy subjects. Percentage mutant fraction was highest in CHB-HCC than only CHB patients. Significant association TP53. R249M with smoking was observed in CHB-HCC patients. Poor survival was observed in HCC patients with combined TP53 and CTNNB1 gene mutation. Conclusion: Driver mutation screening for TP53 and CTNNB1 gene can be done in ctDNA for early diagnosis and prognosis.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Open Access article. This paper presents the use of selenium nanoparticles for the application of information storage in two terminal electronic memory devices. Selenium is a semi-metal with interesting electronic and optical properties that have seldom been studied in terms of electronic memory. In this study selenium nanoparticles have been demonstrated as an embedded charge storage layer between silicon oxide tunnel layer and silicon nitride blocking layer. The electrical characterisation demonstrates clear evidence that charge storage is taking place, and that it is indispensable without the presence of nanoparticles. AFM images show that selenium nanoparticles are almost uniformly distributed on Silicon substrate having a thin silicon dioxide tunnelling layer, and the electrical retention measurement shows potential for long term data storage

Objective: To evaluate the role of shear wave elastography (SWE) of suspicious axillary lymph nodes and its combination with B-mode USG in predicting nodal metastasis in breast cancer patients. Methods: Prospective observational study was performed from June 2018 to August 2020 on breast cancer patients with suspicious axillary nodes on USG. B-mode features (cortical thickness, effacement of fatty hilum, non-hilar blood flow and round shape) and SWE parameters (Emax, Emin, Emean and ESD) of the node with the thickest cortex were evaluated. Diagnostic performances of USG, SWE and their combination were estimated using pathological status of the node on biopsy as the gold standard. Results: Of the 54 patients evaluated, optimal elasticity maps were obtained in 49 nodes of 49 patients (mean age, 46.3 ± 12.1 years; 48/49 (98%) females). On biopsy, 38 nodes (77.6%) had metastasis, while 11 (22.4%) had reactive hyperplasia. Emax, Emin, Emean and ESD of both cortex and hilum were significantly higher in metastatic than reactive nodes. Emax (cortex) ≥14.9 kPa had the best diagnostic performance (sensitivity, 73.7%; specificity, 81.8%). Cortical thickness ≥6.7 mm had the best diagnostic performance among B-mode features (sensitivity, 89.5%; specificity, 72.7%). Combining cortical thickness with effacement of fatty hilum and/or non-hilar blood flow yielded sensitivity of 89.5% and specificity of 90.9%. Addition of Emax (cortex) to cortical thickness and combination of ≥2 B-mode features increased their specificities to 90.9 and 100%, respectively. Conclusions: Metastatic axillary nodes are stiffer than reactive nodes on SWE in breast cancer patients. Emax (cortex) has the best diagnostic performance in differentiating between reactive hyperplasia and nodal metastasis. Combination of Emax (cortex) and cortical thickness increases the specificity for diagnosing metastasis, especially in nodes showing only cortical thickening. Advances in knowledge: Combination of SWE and B-mode USG is highly specific for differentiating metastasis from reactive hyperplasia in suspicious nodes of breast carcinoma patients, especially in nodes with only cortical thickening.

open access article Organic memory devices are a rapidly evolving field with much improvement in device performance, fabrication, and application. But the reports have been disparate in terms of the material behavior and the switching mechanisms in the devices. And, despite the advantages, the lack of agreement in regards to the switching behavior of the memory devices is the biggest challenge that the field must overcome to mature as a commercial competitor. This lack of consensus has been the motivation of this work wherein various works are compiled together to understand influencing factors in the memory devices. Different works are compared together to discover some clues about the nature of the switching occurring in the devices, along with some missing links that would require further investigation. The charge storage mechanism is critically analyzed alongside the various resistive switching mechanisms such as filamentary conduction, redox-based switching, metal oxide switching, and other proposed mechanisms. The factors that affect the switching process are also analyzed including the effect of nanoparticles, the effect of the choice of polymer, or even the effect of electrodes on the switching behavior and the performance parameters of the memory device.

This chapter discusses research and development of emerging silicon-based flexible solar cells. More emphasis is shown on the technology, underlying principles, device architecture, fabrication process, strengths, and challenges of the flexible solar cells fabricated using silicon. This chapter considers all the counterparts of silicon, from bulk to nanostructures that are used to fabricate photovoltaic devices. Change in the structure (low-dimensional and bulk materials), morphology (surface texturing and pyramid structures), and crystallinity (amorphous, poly-crystalline, and crystalline) of silicon as an absorber layer has shown enhanced efficiencies and reliabilities in flexible silicon solar cells. Flexibility and stretchability in solar cells are achieved mainly due to the adoption of novel structures, fabrication techniques, and, most importantly, the adoption of various flexible substrates (metal foils, polymers, and thin glass). The advantages and disadvantages of solar cells are discussed in terms of achieved efficiency, fabrication method, flexibility, and chosen substrate.

Most endangered species exist today in small populations, many of which are isolated. Evolution in such populations is largely governed by genetic drift. Empirical evidence for drift affecting striking phenotypes based on substantial genetic data are rare. Approximately 37% of tigers (Panthera tigris) in the Similipal Tiger Reserve (in eastern India) are pseudomelanistic, characterized by wide, merged stripes. Camera trap data across the tiger range revealed the presence of pseudomelanistic tigers only in Similipal. We investigated the genetic basis for pseudomelanism and examined the role of drift in driving this phenotype's frequency. Whole-genome data and pedigree-based association analyses from captive tigers revealed that pseudomelanism cosegregates with a conserved and functionally important coding alteration in Transmembrane Aminopeptidase Q (Taqpep), a gene responsible for similar traits in other felid species. Noninvasive sampling of tigers revealed a high frequency of the Taqpep p.H454Y mutation in Similipal (12 individuals, allele frequency = 0.58) and absence from all other tiger populations (395 individuals). Population genetic analyses confirmed few (minimal number) tigers in Similipal, and its genetic isolation, with poor geneflow. Pairwise FST (0.33) at the mutation site was high but not an outlier. Similipal tigers had low diversity at 81 single nucleotide polymorphisms (mean heterozygosity = 0.28, SD = 0.27). Simulations were consistent with founding events and drift as possible drivers for the observed stark difference of allele frequency. Our results highlight the role of stochastic processes in the evolution of rare phenotypes. We highlight an unusual evolutionary trajectory in a small and isolated population of an endangered species.

Presently, there is a rapid growth of interest in the area of flexible electronics. Benefits such as light weight, durability, and low cost are among the most appealing aspects. However, the high temperatures throughout the fabrication processes are still the main hurdle. In this study, the deposition of silicon nanowires (SiNWs) at low temperature (300 °C) using tin (Sn) catalyst is studied. Silicon nanostructures have been the center of research for many years for a number of applications in different areas. Chemical vapor deposition (CVD) and other industrial deposition techniques for the growth of crystalline silicon micro- and nanostructures use high temperatures and therefore are not compatible with temperature-sensitive substrates. This work utilizes a low-temperature deposition method for the growth of SiNWs and creates a leeway to use flexible plastic sheets as substrates. The silicon nanowires were deposited by exploiting the vapor–liquid–solid (VLS) material growth mechanism using the plasma-en...

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. A high density of silicon nanowires for solar cell applications was fabricated on a single crystalline silicon wafer, using low eutectic temperature metal catalysts, namely, gallium, indium, tin, and bismuth. The use of silicon nanowires is exploited for light trapping with an aim to enhance the efficiency of solar cells. Additionally, we have optimized the deposition parameters so that there is merely deposition of amorphous silicon along with the growth of silicon nanowires. Thus, it may improve the stability of silicon-based solar cells. The different catalysts used are extensively discussed with experimental results indicating stable growth and highly efficient silicon nanowires for photovoltaic applications. To test the stability, we measured the open-circuit voltage for four hours and the change in voltage was ±0.05 V. The fabrication of all-crystalline silicon solar cells was demonstrated using the conventional mature industrial manufacturing process that is presently used for the amorphous silicon solar cells. To summarize, this research compares various post-transition metals as a catalyst for the growth of nanowires discussing their properties, and such silicon nanowires can be utilized in several other applications not only limited to photovoltaic research.

Antibacterial efficacy of nanoscale silver, copper (II) oxide and zinc oxide were assessed against Pseudomonas aeruginosa and Staphylococcus aureus biofilms in solution and on surfaces. Using a Center for Disease Control biofilm reactor, minimum biofilm reduction concentrations, the coefficient of determination (R2) and log(10) reductions were determined. Atomic absorption spectroscopy, scanning electron microscopy and confocal laser scanning microscopy were used to assess the disruption of the biofilms. The efficacy of thin films of zinc oxide and silver deposited via magnetron sputtering and thermal evaporation respectively was also assessed. Minimum biofilm reduction concentrations of zinc oxide or silver nanoparticles were 256 or 50 µg/ml for P. aeruginosa and 16 or50 µg/ml for S. aureus respectively. When tested in combination the nanoparticles concentrations were at least halved resulting in significant (p ≤0.05) biofilm reductions of 3.77 log(10) - 3.91 log(10). Biofilm growth on thin films resulted in reductions of up to 1.82 log(10). The results suggest that nanoparticle suspensions and thin films of zinc oxide and may have potential as antimicrobial treatments for hard to eliminate biofilms in a clinical environment.

Recent strategy in the electronics sector is to ascertain the ways to make cheap, flexible and environmentally friendly electronic devices. The 3D inkjet printing technology is based on the Additive Manufacturing concept and it is with no doubt capable of revolutionising the whole system of manufacturing electronic devices including: material selection; design and fabrication steps and device configuration and architecture. Thus, 3D inkjet printing technology (IJP) is not only one of the most promising technologies to reduce the harmful radiation/ heat generation but also achieve reductions in manufacturing cost. Here, we explore the potential of 3D – inkjet printing technology to provide an innovative approach for electronic devices in especially information storage elements by seeking to manufacture and characterise state-of-art fully inkjet printed two terminal electronic memory devices. In this work, ink-jettable materials (Ag and PEDOT:PSS) were printed by a piezoelectric Epson Stylus P50 inkjet printing machine on a flexible substrate. All components of the memory cells of a simple metal/active layer/metal structure were deposited via inkjet printing. The quality of the printed layers was first assessed by Nikon LABOPHOT-2 optical microscope, fitted with Nikon Camera DS-Fi1. Furthermore, an in-depth electrical characterisation of the fabricated memory cells was carried out using HP4140B picoammeter.

Farmer profit can be increased and air quality improved

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Effect of plasma treatment on transparent conductive oxides (TCOs) including indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO) and aluminium-doped zinc oxide (AZO) are discussed. Stability of electrical and optical properties of TCOs, when exposed to plasma species generated from gases such as hydrogen and silane, are studied extensively. ITO and FTO thin films are unstable and reduce to their counterparts such as Indium and Tin when subjected to plasma. On the other hand, AZO is not only stable but also shows superior electrical and optical properties. The stability of AZO makes it suitable for electronic applications, such as solar cells and transistors that are fabricated under plasma environment. TCOs exposed to plasma with different fabrication parameters are used in the fabrication of silicon nanowire solar cells. The performance of solar cells, which is mired by the plasma, fabricated on ITO and FTO is discussed with respect to plasma exposure parameters while showing the advantages of using chemically stable AZO as an ideal TCO for solar cells. Additionally, in-situ diagnostic tool (optical emission spectroscopy) is used to monitor the deposition process and damage caused to TCOs.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. We report the growth of self-doped silicon nanowires (SiNWs), using gallium and bismuth catalysts, by employing a vapour-liquid-solid method. This enables the formation of both p- and n-doped nanowires without the use of expensive and toxic gases that are conventionally used and opens a new route to a simplified and cost effective process for doping SiNWs. The chosen catalysts have the lowest eutectic temperature available for the growth of silicon nanowires. The growth of self-doped SiNWs, for the fabrication of photovoltaic cells, has been demonstrated for the first time in this study.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. This work focusses on the metal-semiconductor contact on n-type c-Si wafers and explore the possibility of using magnesium (Mg) to form electron–selective contacts instead of using the conventional Au-Sb films which requires high temperature annealing between 350 and 500 °C. Aluminium (Al) capping layer was added over the magnesium contacts to prevent oxidation of magnesium. Various electrical measurements were performed over thermally evaporated Mg/Al contacts to investigate the conduction properties on both p-type and n-type silicon, where a Schottky behaviour was observed for the p doped silicon, but an ohmic behaviour (V ∝ I) for the n-type doped c-Si samples. The results were further optimised after investigating various thicknesses of the Mg interlayer, with 10 nm of Mg interlayer found to have the least resistance. The resistivity of the optimised structure (n-Si/Mg-10 nm/Al) was calculated, and measurements according to the Transmission Line Method (TLM) showed a contact resistivity of 462mΩ cm2 ± 20mΩ cm2. Further investigations were also conducted on the effect of high temperature annealing of the magnesium contact, which showed an increase in resistance with increase in annealing temperature, with the lowest resistance obtained without annealing. Additional investigations focussed on the morphological analysis of the deposited magnesium and its impact on the electrical characteristics.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Selection of a material that serves multiple purposes is always beneficial for any electronic device including solar cells. This study investigates nickel oxide (NiO) as a multipurpose material to overcome the potential issues observed in traditional solar cells. A proof-of concept device is fabricated to understand the efficient hole transport from NiO while blocking electrons as determined by I-V measurements showing suppression of dark current and enhancement in the power conversion from the solar cell. Enhanced surface defects in the silicon nanowires (SiNWs) leading to the poor carrier collection is possible to be improved by the selection of wide bandgap metal-oxides that show high band offset for one carrier (electron/hole) while negligible band offset for another carrier (hole/electron) is discussed. Furthermore, Fermi level de-pinning for NiO sandwiched between different metal electrodes and SiNWs, signifying that the selection of appropriate metal electrodes is another key factor in improving the efficiency of solar cells; which is experimentally studied in this work. As fabricated solar cells in this work do not use high temperature diffused P[sbnd]N junction to separate the charge carriers neither toxic gases for doping SiNWs.

open access journal Nowadays, the environmental issues surrounding the production of electronics, from the perspectives of both the materials used and the manufacturing process, are of major concern. The usage, storage, disposal protocol and volume of waste material continue to increase the environmental footprint of our increasingly “throw away society”. Almost ironically, society is increasingly involved in pollution prevention, resource consumption issues and post-consumer waste management. Clearly, a dichotomy between environmentally aware usage and consumerism exists. The current technology used to manufacture functional materials and electronic devices requires high temperatures for material deposition processes, which results in the generation of harmful chemicals and radiation. With such issues in mind, it is imperative to explore new electronic functional materials and new manufacturing pathways. Here, we explore the potential of additive layer manufacturing, inkjet printing technology which provides an innovative manufacturing pathway for functional materials (metal nanoparticles and polymers), and explore a fully printed two terminal electronic memory cell. In this work, inkjetable materials (silver (Ag) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)) were first printed by a piezoelectric Epson Stylus P50 inkjet printer as stand-alone layers, and secondly as part of a metal (Ag)/active layer (PEDOT:PSS)/metal (Ag) crossbar architecture. The quality of the individual multi-layers of the printed Ag and PEDOT:PSS was first evaluated via optical microscopy and scanning electron microscopy (SEM). Furthermore, an electrical characterisation of the printed memory elements was performed using an HP4140B picoammeter.

research groups involved: 1. Emerging Technologies Research Centre, De Montfort University, Leicester, United Kingdom 2. Engineering and Energy, Murdoch University, Murdoch, Australia 3. Malaviya National Institute of Technology, Jaipur, India 4.School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Lithium-ion batteries (LIBs) gained global attention as the most promising energy storing technology for the mobile and stationary applications due to its high energy density, low self-discharge property, long life span, high open-circuit voltage and nearly zero memory effects. However, to meet the growing energy demand, this energy storage technology must be further explored and developed for high power applications. The conventional lithium-ion batteries mainly based on Li-ion intercalation mechanism cannot offer high-charge capacities. To transcend this situation, alloy-type anode and conversion-type anode materials are gaining popularity. This review article focuses on the historical and recent advancements in cathode and anode materials including the future scope of the lithium nickel manganese cobalt oxide (NMC) cathode. Equal emphasis is dedicated in this review to discuss about lithium based and beyond lithium-based anode materials. This review additionally focuses on the role of technological advancements in nanomaterials as a performance improvement technique for new novel anode and cathode materials. Also, this review offers rational cell and material design, perspectives and future challenges to promote the application of these materials in practical lithium-ion batteries.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. In this study, hydrogenated amorphous carbon (a-C:H) films are investigated for electronic applications as an insulating layer. a-C:H films were deposited using radio frequency-Plasma enhanced chemical vapour deposition (RF-PECVD) technique at room temperature. For the first time, the properties of a-C:H films as a function of annealing temperature is investigated, with a focus on their electrical and optical properties. This study shows that a-C:H films are stable up to 450ºC. This investigation will facilitate the use of a-C:H films as an insulating layer where the semiconductor active layers are deposited at higher temperatures (e.g. amorphous silicon deposited around 300ºC for thin film transistor TFTs). In addition to understanding the electrical and optical properties of annealed a-C:H films, we have further explored and studied its suitability in Flash-type memory devices. Various forms of diamond-like carbon are considered to have a high chemical resistance; no extensive data are available in the literature on this subject. The stability of a-C: H thin films with various reactive chemicals, commonly used in organic/printable electronic devices, is also investigated in this work. The findings may provide opportunities for adoption/integration of a-C:H in hybrid organic-inorganic electronic devices.

Open access article This study fabricated and demonstrated a functional, stable electrode structure for a high capacity Li-ion battery (LIB) anode. Effective performance is assessed in terms of reversible lithiation for a significant number of charge–discharge cycles to 80% of initial capacity. The materials selected for this study are silicon and tin and are co-deposited using an advanced manufacturing technique (plasma-enhanced chemical vapour deposition), shown to be a scalable process that can facilitate film growth on 3D substrates. Uniform and hybrid crystalline–amorphous Si nanowire (SiNW) growth is achieved via a vapour–liquid–solid mechanism using a Sn metal catalyst. SiNWs of less than 300 nm diameter are known to be less susceptible to fracture and when grown this way have direct electrical conductivity to the current collector, with sufficient room for expansion. Electrochemical characterisation shows stable cycling at capacities of 1400 mA h g 1 (>4 the capacity limit of graphite). This hybrid system demonstrates promising electrochemical performance, can be grown at large scale and has also been successfully grown on flexible carbon paper current collectors. These findings will have impact on the development of flexible batteries and wearable energy storage.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Core–shell silicon–silicon oxide nanowires are synthesized at low temperatures using inorganic and organic compounds of a tin as a catalyst. In situ simultaneous one-dimensional growth of pristine silicon nanowires (SiNWs) using alloy catalyst is reported here. Such a development process generates a high-quality SiNW that is not determined by other atomic species in the plasma. A possible growth model is discussed to understand the synchronized precipitation of a SiNW core and an oxide shell. Nanowires grown here eliminate the additional fabrication steps to deposit anticipated oxide shell that is achieved by precipitation from the same catalyst that precipitates core nanowires.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Flexible Semi-Transparent electronic memory would be useful in coming years for integrated flexible transparent electronic devices. However, attaining such flexibility and semi-transparency leads to the boundaries in material composition. Thus, impeding processing speed and device performance. In this work, we present the use of inorganic stable selenium nanoparticles (Se-NPs) as a storage element and hydrogenated amorphous carbon (a-C:H) as an insulating layer in two terminal non-volatile physically flexible and semi-transparent capacitive memory devices (2T-NMDs). Furthermore, a-C:H films can be deposited at very low temperature (

Silicon nanostructures are discussed in this chapter. First, the field of nanotechnology in relation to the properties and basic physical phenomena of nanomaterials is presented. Then, the current status of nanomaterials used for memory storage devices is reviewed. Vapour–liquid–solid method is described in details as the most common techniques to fabricate silicon nanostructures. In addition, a brief discussion on various metals for the role of the catalyst material is provided.

The growth in the usage of organic material s in the fabrication of electronic devices owes to the ease of fabrication of organic electronic devic es as well as the applicability of inexpensive substrates in such configurations [1]. Nano-compos ite polymer memory devices are fabricated by depositing a blend (an admixture of organic poly mer, small organic molecules and nanoparticles) between two metal electrodes. These devices show two electrical conductance states (“1” and “0”) when voltage is applied, thus rendering the structures suitable for data retention. These two states can be viewed as the re alisation of non-volatile memory. Nano-composite polymer memory devices comprising of a blend of a polymer and small molecules and/or nanoparticles are investigated [2, 3,4,5,6]. This study is aimed at further understanding the electrical bistability observed i n such devices. This work also investigates if an electrical charge can be transferred to gold nano-p articles and, between small molecule complexes. The electric force microscopy was used for charging the gold-nanoparticles. Current-Voltage (I-V) and Capacitance-Voltage (C-V) techniques were also employed in studying the charge transfer between small organic molecules (Donor-Acceptor pair). On the basis of this investigation our earlier model [5], based on electric dipoles formation in polymer matrix, is further scrutinised. The progress in the nano-composite polymer memory devices over the last ten years will be presented, and invoke the conundrums that scholars of this field are currently faced with, such as questions about the electrical charging mechanism a nd stability of devices, proposed theories explaining the experimental data, contradictions in the published work by different groups. The proposed answers to the puzzles, wherever applicabl e, will be presented. The pre-requisites for the realisation of these memory devices will also b e presented.

This is an Open Access article. Intensive research is currently underway to exploit the highly interesting properties of nano-bits (“nano-sized particles and molecules”) for optical, electronic and other applications. The basis of these unique properties is the small-size of these structures which result in quantum mechanical phenomena and interesting surface properties. The small molecules and/or nano-particles are selected in such a way so that it can create an internal electric in the nano-composite. We define a nanocomposite is an admixture of small molecules and/or nano-particles and a polymer. We have demonstrated the internal electric field in our devices, made from nano-bits (nano-particles and/or molecules) and insulating materials, can contribute to the electrical bistability i.e. two conductive states.

Fresh-cut spinach leaves were stored for 4 days at 15C and 75% relative humidity under modified atmosphere packaging to assess the impact of differential in-pack gas atmospheres generated through different packaging films and variable in-pack weight on the quality of stored produce. After 4 days of storage, retention of chlorophyll, β-carotene and ascorbic acid was better in low-density polyethylene (LDPE) packages than in polypropylene (PP) packages. LDPE film-packaged samples had higher phenolic content than PP film-packaged samples. Low in-pack O2 (1–2 kPa) along with the buildup of CO2 (8–10 kPa) seems to have enhanced the retention of antioxidant components, i.e., β-carotene and ascorbic acid, in LDPE packages. This helped in chlorophyll retention and also prevented formation of oxidation compounds of phenols that otherwise caused browning of cut surfaces. Thus, O2 and CO2 permeability of packaging film or in-pack weight of produce might be such that equilibrated O2 partial pressures remain near to 1–2 kPa so as to affect a beneficial increase in the phenolic content along with concomitant retention of chlorophyll. PRACTICAL APPLICATIONS Fresh-cut spinach leaves have received an enormous demand due to their utility in various traditional Indian preparations. Shelf life and quality of fresh-cut produce may be greatly reduced due to high rates of respiration. Traditional packaging and handling techniques reduce the shelf life and sensory quality of fresh-cut spinach. Temperature control and atmospheric modifications help to maintain produce quality by reducing respiration rate and enhance shelf life by minimizing the adverse effects of cutting. This research focused on evaluation of respiratory behavior of fresh-cut spinach leaves at a temperature commonly encountered during transportation and retail distribution, i.e., 15C, and the effect of different polymeric films and in-pack weights on produce quality. The results of the study suggest that packaging of fresh-cut spinach in polymeric film packages could maintain the sensory quality and reduce degradation of various physicochemical constituents. Utilization of the results for proper design of modified atmosphere packages for this highly perishable produce can prove to be extremely beneficial for safe storage and transportation to urban retail markets.

There has been a number reports on polymer memory devices for the last one decade. Polymer memory devices are fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and nanoparticles) between two metal electrodes. These devices show two electrical conductance states (“1” and “0”) when voltage is applied, thus rendering the structures suitable for data retention. These two states can be viewed as the realisation of memory devices. However, polymer memory devices reported so far suffer from multiple drawbacks that render their industrial implementation premature. There is a large discrepancy in the results reported by different groups. This article attempts to answer some of the questions.

White button mushroom accounts for 35–45% of the total mushroom produced in the world. Modified atmosphere packaging or MAP is a technology that, along with low temperature storage, helps in extending the shelf life and maintenance of quality of the produce packaged in polymeric films. The present study mathematically modeled the various transport processes associated with the mushroom under MAP at 15C and 75% relative humidity (RH) using the enzyme kinetics approach. Low density polyethylene (LDPE), polypropylene (PP) and oriented polypropylene (OPP) films were used to pack the mushroom. Numerical solutions to the transient state equations were programed in a computer programing language to predict the in-pack gaseous partial pressures at any instant of time. The model was experimentally validated, and a simple qualitative tool based upon optimum whiteness of mushroom was developed using the predictions to determine the safe period of storage. The predicted and experimental in-pack partial pressures of O2 and CO2 were in fair agreement with each other. In the OPP film packages, the O2 and CO2 levels stabilized around 6.87 and 12.93 kPa, respectively. Whereas, O2 levels decreased drastically in LDPE and PP film packages. A combination of predicted in-pack environment in all the film packages, storage time and whiteness of mushroom led to the conclusion that mushrooms can be stored safely for 32, 44 and 108 h in the gaseous environment available in the LDPE, PP and OPP film packages, respectively. PRACTICAL APPLICATIONS The empirical approach followed in this study through assimilation of various transient state in-pack variables with a single qualitative attribute of mushroom can serve as a measure of assessment of the mushroom's safe storage period under modified atmosphere packaging. Further, the mathematical approach suggested in this study can also serve as a benchmark for its application to other fruits and vegetables, taking into consideration their respective limiting qualitative characteristics. Thus, the results detailed in the study can be easily applied for their direct practical application during storage as well as for further academic exercises.

The capacitance-voltage (C-V) characteristics of thin films of ZrO2 deposited by thermal metal-organic chemical vapour deposition (MOCVD) have been analyzed. The films were grown at three different temperatures (500, 550 and 600 ºC) and 1 mbar pressure from a novel monomeric zirconium amide-guanidinate complex [Zr(NEtMe)2(guanidinate)2]. The true capacitance was determined from measurements made at different frequencies in order to account for the series and shunt parasitic resistances during C-V measurements. Films grown at 500 and 550 ºC showed no hysteresis while those grown at 600 ºC exhibited a very small hysteresis window ≈0.16 V for O2 flow of 100 sccm and ≈0.19 V for 50 sccm O2 flow. A very small voltage shift is also obtained for the device under 10 hr voltage stress. These preliminary in-depth electrical results suggest that quality ZrO2 can be grown from the novel [Zr(NEtMe)2(guanidinate)2] complex precursor paving the way for their use as future gate dielectrics.

The evaluation of transient-state in-pack respiration rates for oxygen (O2) consumption and carbon dioxide (CO2) evolution at any instant of time for a commodity packaged in polymeric film packages and kept under modified atmosphere (MA) for long-term storage requires regular analysis of the in-pack partial pressures of O2 and CO2. Enzyme kinetic theory has been observed to make near-accurate predictions of the respiration rates of many commodities under MA. This approach was followed to evaluate the respiration rates of the ‘button’ mushroom, packaged in low-density polyethylene (LDPE), polypropylene (PP) and oriented polypropylene (OPP) film packages at any instant of time, utilising the produce, package and the environmental parameters. The respiration model parameters under the specified environmental conditions of 15 °C and 75% relative humidity (RH) were evaluated using multiple regression analysis and were utilised to know the predicted rates of respiration for O2 consumption and CO2 evolution. The experimental in-pack partial pressures of O2 and CO2 under all the packaging treatments agreed fairly well with the predicted values for a storage period of 96 h. The predicted rates of respiration dropped drastically in LDPE and PP film packages, but arrived to near-constant levels (115 and 110 ml kg−1 h−1 for the O2 consumption and CO2 evolution, respectively) in the OPP film packages after 36 h, indicating the condition of gaseous equilibrium in these packages. Results of the study confirm that the enzyme kinetics approach can be used to predict the respiration rates of any commodity under MA in polymeric films.

This output led to an EPSRC research grant funding EP/E047785/1 (£207k) and a CASE studentship (with direct support from the National Physical Lab, (Dr Josephs-Franks, Patrick.Josephs-Franks@npl.co.uk). Research related to this output also led to an invitation to be guest editor of the Philosophical Transaction of the Royal Society A, three invited talks (Electronic Processes in Organic Materials, Crimea, Ukraine; Printed Electronics Europe 2007, Cambridge, UK and XVI International Materials Research Congress, Cancun, Mexico, 2007) and an invitation to organise and chair a special session on “Recent development in electrical writable organic memory devices” for CIMTEC08 (Italy).

As a high-quantum-efficiency photocatalyst, the serious photo-corrosion of silver phosphate (Ag3PO4), limits the practical applications in water purification and challenges us. Herein, Ag3PO4 is found to have a high stability under natural indoor weak light irradiation, suggesting that we can employ it by adopting a new application strategy. In our studies, rhodamine B (RhB, cationic dye), methyl orange (MO, anionic dye) and RhB-MO mixture aqueous solutions are used as the probing reaction for the degradation of organic wastewater. It is found that RhB, MO and RhB-MO can be completely degraded after 28 h under natural indoor weak light irradiation, indicating that multi-component organic contaminants can be efficiently degraded by Ag3PO4 under natural indoor weak light irradiation. The density of natural indoor weak light is measured to be 72cd, which is merely one-thousandth of 300 W xenon lamp (68.2 × 10(3)cd). Most importantly, Ag3PO4 shows a high stability under natural indoor weak light irradiation, demonstrated by the formation of fairly rare Ag. Furthermore, we also investigate the influence of inorganic ions on organic dyes degradation. It shows that the Cl(-) and Cr(6+) ions with high concentrations in wastewater have significantly decreased the degradation rate. From the viewpoint of energy saving and stability, this study shows us that we can utilize the Ag-containing photocatalysts under natural indoor weak light, which could be extended to indoor air cleaning process.

The transmittance and absorbance data of nickel oxide films are crucial in determining it's optical properties. Selection of substrate is important for a greater understanding of optical constants and properties of a material. In view of this Nickel oxide films were deposited on Quartz substrates and it's properties are compared with Nickel oxide films deposited on glass. We show the difference in optical constants measured for Nickel oxide thin film deposited on glass and quartz substrates.

Nickel oxide has been investigated for several potential applications, namely, ultraviolet detectors, electro chromic devices, displays, diodes for light emitting, transparent conductive electrode, and optoelectronic devices. These applications require an in depth analysis of nickel oxide prior to its exploration in aforementioned devices. Optical properties of materials were investigated by depositing thin film of nickel oxide on different substrates in order to understand if the choice of substrate can have effect on deducing various optical parameters and can lead to wrong conclusions. In view of this, we have investigated optical properties of nickel oxide deposited on different substrates (glass, transparent plastic, sapphire, potassium bromide, and calcium fluoride).

We discuss a novel inverse problem in which the data is generated by the sequential contractive projections of the convolution of two unknown functions, both of which we aim to learn. The method is illustrated using an application that relates to the multiple inversions of image data recorded with a scanning electron microscope, with the aim of learning the density of a given material sample and the microscopy correction function. Given the severe logistical difficulties in this application of taking multiple images at different viewing angles, a novel imaging experiment is undertaken, resulting in expansion of information. In lieu of training data, it is noted that the highly discontinuous material density function cannot be modelled using a Gaussian process (GP) as the parametrisation of the required nonstationary covariance function of such a GP cannot be achieved without training data. Consequently, we resort to estimating values of the unknown functions at chosen locations in their domain—locations at which an image data are available. Image data across a range of resolutions lead to multiscale models which we use to estimate material densities from the micrometre to nanometre length scales. We discuss applications of the method in nondestructive learning of material density using simulated metallurgical image data, as well as perform inhomogeneity detection in multicomponent composite on nanometre scales, by inverting real image data of a brick of nanoparticles.

Various methods have been employed before to deduce the density of states (DOS) in amorphous carbon. However, further investigations show that capacitance measurements on a metal-insulator-semiconductor structure are an appropriate way to deduce the DOS. Thus, an analytical formalism, which agrees well with the experimental data, is developed. This paper reports the structures and techniques used to investigate the DOS in amorphous hydrogenated carbon.

In this work, we demonstrate a hybrid silicon-organic nanocrystal floating gate memory device combining organic insulating materials, metal nanoparticles and Si MOSFET. The nanocrystals were organically passivated gold nanoparticles (Au-nps) forming a monolayer which was deposited by Langmuir–Blodgett (LB) technique. The FET device is fabricated on a Silicon-on-Insulator (SOI) substrate using conventional silicon processing. The nanoparticle layer is separated from the channel area of the FET with a 5 nm thermal SiO2 film and is isolated from the Al gate contact with a LB-deposited organic insulator layer. The memory effect is tested by means of threshold voltage shift measurements under different program/erase pulses. The nanocrystals can be charged either from the channel through the thermal oxide layer or from the gate through the organic insulator depending on the pulse applied pulse characteristics.