Layer by layer printing of nanomaterials for large-area, flexible electronics

Large-area electronics, including printable and flexible electronics, is an emerging concept which aims to develop electronic components in a cheaper and faster manner, especially on those non-conventional substrates. Being flexible and deformable, this new form of electronics is regarded to hold great promises for various futuristic applications including the internet of things, virtual reality, healthcare monitoring, prosthetics and robotics. However, at present, large-area electronics is still nowhere near the commercialisation stage, which is due to several problems associated with performance, uniformity and reliability, etc. Moreover, although the device’s density is not the major concern in printed electronics, there is still a merit in further increasing the total number of devices in a limited area, in order to achieve more electronic blocks, higher performance and multiple functionalities. In this context, this Ph.D. thesis focuses on the printing of various nanomaterials for the realisation of high-performance, flexible and large-area electronics. Several aspects have been covered in this thesis, including the printing dynamics of quasi-1D NWs, the contact problem in device realisation and the strategy to achieve sequential integration (3D integration) of the as-printed devices, both on rigid and flexible substrates. Promisingly, some of the devices based on the printed nanomaterial show a comparable performance to the state-of-the-art technology. With the demonstrated 3D integration strategy, a highly dense array of electronic devices can be potentially achieved by printing method. This thesis also touches on the problem associated with the circuit and system realisation. Specifically, graphene-based logic gates and NW based UV sensing circuit has been discussed, which shows the promising applications of nanomaterial-based electronics. Future work will be focusing on extending the UV sensing circuit to an active matrix sensor array

Bioaccessibility of folate in cereals and legumes : the role of endogenous vitamers

Folate is essential for human health, playing a vital role in the metabolism of nucleic and amino acids. However, folate intake is below the recommendation in many countries. Mandatory folic acid fortification is practised in more than 80 countries around the world, but not, for example, in most EU countries. Additionally, there are concerns about excessive folic acid intake. Therefore, studying folate from natural sources, such as cereal and legume-based foods, is important. Unlike enriched folic acid, natural folates need to be liberated from the food matrix, and, further, most of them are unstable and can be lost during digestion. Thus, to understand the role of a food as a folate source, it is necessary to consider the bioaccessibility of folate, meaning the proportion of folate potentially available for absorption. However, knowledge about folate bioaccessibility in foods is still limited, especially at the vitamer level. Furthermore, the mechanisms behind how food matrices influence folate bioaccessibility are not well understood. This thesis aimed to investigate the bioaccessibility of endogenous folate in cereals and legumes. Folate bioaccessibility in cereal and legume matrices (flours, pastes and breads) was compared first. Next, the stability of folate vitamers during in vitro digestion was studied. Then, the effects of ingredients and processing methods on folate bioaccessibility were investigated. Finally, the significance of 5-methyltetrahydrofolate to folate bioaccessibility was examined. Samples were subjected to a static in vitro digestion model, and folates were analysed using ultra-high-performance liquid chromatography (UHPLC) coupled with photodiode array and fluorescence detection. Folate bioaccessibility in cereal and legume matrices ranged from 31% to 123%. Faba bean matrices generally had better folate bioaccessibility than cereal matrices. Among the breads, rye breads typically had higher folate bioaccessibility, and oat breads had lower folate bioaccessibility than the other breads. Three common trends in folate stability during in vitro digestion were found: (1) high stability of formyl pool folates, but frequent interconversion among formyl folates (10-formyldihydrofolate, 5-formyltetrahydrofolate) and 5,10-methenyltetrahydrofolate; (2) the decrease of reduced folates (tetrahydrofolate, 5-methyltetrahydrofolate, and 5-formyltetrahydrofolate); and (3) high stability of oxidised folates (folic acid and 10-formylfolic acid). These changes were universal for all studied food matrices, but the degree varied. 5-methyltetrahydrofolate was more stable in legume matrices than in cereal matrices. Both the ingredients and the processing methods affected the bioaccessibility of folate. Because of a larger formyl folate pool, whole-grain wheat bread had better folate bioaccessibility than white wheat bread. The inclusion of faba bean flour as a baking ingredient not only introduced a large formyl pool but also stabilised 5-methyltetrahydrofolate during digestion, improving both the folate content and bioaccessibility in bread. Folate bioaccessibility was easily improved with a simple paste making process. Conversely, baking with added yeast significantly enhanced the 5-methyltetrahydrofolate level in breads but decreased their folate bioaccessibility due to the instability of 5-methyltetrahydrofolate. Further experiments showed that 5-methyltetrahydrofolate was crucial for folate bioaccessibility and its stability in food matrices during the in vitro digestion was a trade-off between the pro-oxidative and protective factors. However, phenolic compounds could act as protective factors in stabilising 5-methyltetrahydrofolate. In summary, folates underwent significant changes during digestion. However, food matrices can be modified to turn these changes towards better folate bioaccessibility. Faba bean was shown to be a promising dietary source of folate. In addition to folate content, bioaccessibility should be considered when evaluating foods as folate sources.B-ryhmän vitamiineihin kuuluvaa folaattia tarvitaan mm. nukleiinihappojen synteesiin ja aminohappojen aineenvaihduntaan. Folaatin saanti jää usein alle suositusten. Sikiöiden hermostoputken sulkeutumishäiriöiden ehkäisemiseksi monessa maassa viljavalmisteita täydennetään foolihapolla. Tämä ei kuitenkaan ole yleistä EU:ssa, ja siksi on tärkeää tutkia elintarvikkeiden luontaista folaattia. Pitoisuuksien lisäksi voidaan tarkastella folaatin biosaatavuutta (bioaccessibility), jolla tarkoitetaan sitä osuutta folaatista, joka vapautuu elintarvikkeesta ja voisi imeytyä. Useimmat folaatin muodoista, vitameereista, ovat herkkiä tuhoutumaan. Folaatin biosaatavuutta ei ole juuri tutkittu etenkään vitameeritasolla, eikä elintarvikematriisin vaikutusta biosaatavuuteen ymmärretä hyvin. Väitöskirjatyön tavoite oli tutkia viljojen ja palkokasvien folaatin biosaatavuutta. Biosaatavuutta tutkittiin staattisella in vitro ruoansulatusmallilla, ja folaatit määritettiin erittäin suuren erotuskyvyn nestekromatografialla (UHPLC). Folaatin biosaatavuus vilja- ja palkokasvimateriaaleista – jauhoista, kuumennetuista jauho–vesiseoksista ja leivistä – oli 31–123 %. Vitameerien pysyvyydet ruoansulatusmallissa vaihtelivat, ja elintarvikkeissa yleisesti esiintyvä 5-metyylitetrahydrofolaatti oli pysyvämpi palkokasvi- kuin viljamateriaaleissa. Härkäpavun folaatin biosaatavuus oli parempi kuin viljojen. Ruisleipien folaatin biosaatavuus oli hyvä, kun taas kauraleivissä biosaatavuus oli heikompi. Täysjyvävehnäleivän folaatin biosaatavuus oli parempi kuin valkoisen vehnäleivän, ja härkäpapujauhon käyttäminen leivonnassa paransi sekä leivän folaattitasoa että biosaatavuutta. Biosaatavuutta pystyttiin parantamaan myös yksinkertaisella kuumennuskäsittelyllä. Leivinhiivan käyttäminen nosti kyllä leivän folaattipitoisuutta, mutta heikensi biosaatavuutta hiivan tuottaman 5 metyylitetrahydrofolaatin heikon pysyvyyden vuoksi. 5-Metyylitetrahydrofolaatin pysyvyys osoittautuikin ratkaisevan tärkeäksi folaatin biosaatavuudelle. Fenoliset yhdisteet edistivät 5-metyylitetrahydrofolaatin pysyvyyttä. Tämä väitöskirjatyö osoitti, että elintarvikematriisien muokkauksella ja valmistusaineiden valinnalla voidaan parantaa folaatin biosaatavuutta. Härkäpavun osoitettiin olevan lupaava folaatin lähde. Folaattipitoisuuden lisäksi biosaatavuus tulisi ottaa huomioon arvioitaessa elintarvikkeita folaatin lähteinä

The Planning and Design Strategy from Ecological Civilization Perspective

After experiencing thousands of years of the agricultural civilization and the industrial civilization development, China has finally entered an ecological-civilization stage in recent years, and the environmental protection has become an important gauge for measuring the social economic development. In the procedure of urban and rural construction, the release of the Urban and Rural Planing Decree signifies that the coordinated development of urban and rural planning in our country has entered a significant historical stage. This thesis has summarized and analyzed the common prob-lems existing in domestic urban and rural planning and design. Based on the problems this thesis has made in-depth discussion of the urban and rural planning and design with the ecological civilization issue which has been widely con-cerned in current social development and the implementation of the Urban and Rural Planing Decree being taken into consideration

The bioaccessibility of folate in breads and the stability of folate vitamers during in vitro digestion

Both the liberation and stability of endogenous folate are relevant to the bioaccessibility of folate. Since folates are unstable, in addition to studying the natural folate content in foods, bioaccessibility should be considered. To understand folate changes during digestion, a mixture of standard folate compounds was subjected to a static in vitro gastrointestinal digestion assay. Next, different types of bread were analysed to study how food matrices influence folate bioaccessibility. Folates were identified and quantitated by a UHPLC-PDA/FL method. Folic acid and 10-formylfolic acid were stable throughout the digestion, and the conversions among formyl folates and 5,10-methenyltetrahydrofolate were triggered at the gastric phase. Tetrahydrofolate began to degrade during the oral phase and was lost completely during the gastric phase. During the intestinal phase, 5-methyltetrahydrofolate began to degrade and suffered a 60% loss. With bread matrices, folate conversions and the decrease of reduced folates were also common, but the extent of changes varied. Generally, rye breads had the highest (80–120%) bioaccessibility of folate, while oat breads had the lowest (31–102%). The high proportion of 5-methyltetrahydrofolate could result in low bioaccessibility because of its relatively low stability during digestion in bread matrices. An increase in 10-formylfolic acid content was observed for all the breads, but 10-formyldihydrofolate seemed to be more stable in rye breads than in oat and wheat breads. The results showed that folates undergo significant changes during digestion and that food matrices could be modified to affect these changes towards better folate bioaccessibility.Peer reviewe

5-Methyltetrahydrofolate Is a Crucial Factor in Determining the Bioaccessibility of Folate in Bread

This study investigated the bioaccessibility of folate in wheat bread baked with different ingredients and processing methods. Next, different matrices were spiked with 5-methyltetrahydrofolate, gallic acid (GA), or both to investigate the stability of 5-methyltetrahydrofolate during in vitro digestion. The folate bioaccessibility in bread varied from 44 to 96%. The inclusion of whole-grain or faba bean flour significantly improved both folate content and bioaccessibility. Baking with yeast increased the folate content by 145% in bread but decreased folate bioaccessibility compared to the bread without added yeast because of the instability of 5-methyltetrahydrofolate. Spiking experiments confirmed oxidation as a critical reason for 5-methyltetrahydrofolate loss during digestion. However, GA protected this vitamer from degradation. Additionally, 5-methyltetrahydrofolate was less stable in whole-grain wheat matrices than other matrices. This study demonstrated that the stability of 5-methyltetrahydrofolate is crucial for folate bioaccessibility in bread, and methods for stabilizing this vitamer should be further studied.Peer reviewe

Bioaccessibility of Folate in Faba Bean, Oat, Rye and Wheat Matrices

Cereals and legumes are rich in folate. However, due to the instability of folate, processing and digestion can induce significant folate loss. In this paper, folate bioaccessibility of faba bean, oat, rye and wheat flours and pastes was studied using a static in vitro digestion model. Folate bioaccessibility depended on food matrices, varying from 42% to 67% in flours and from 40% to 123% in pastes. Digestion was associated with the inter conversion of formyl folates, as well as the increase of oxidised vitamers and decrease of reduced vitamers. Especially in faba bean, 5-methyltetrahydrofolate showed surprisingly good stability both in digestion and heat treatment, resulting in high bioaccessibility. The physiological concentration of ascorbic acid did not stabilise folate in digestion; however, a higher level helped to maintain reduced vitamers. Heat treatment (10-min paste making) could improve folate bioaccessibility by liberating folate from the food matrices and by altering folate vitamer distribution.Peer reviewe

Google Scholar is manipulatable

Citations are widely considered in scientists' evaluation. As such, scientists may be incentivized to inflate their citation counts. While previous literature has examined self-citations and citation cartels, it remains unclear whether scientists can purchase citations. Here, we compile a dataset of ~1.6 million profiles on Google Scholar to examine instances of citation fraud on the platform. We survey faculty at highly-ranked universities, and confirm that Google Scholar is widely used when evaluating scientists. Intrigued by a citation-boosting service that we unravelled during our investigation, we contacted the service while undercover as a fictional author, and managed to purchase 50 citations. These findings provide conclusive evidence that citations can be bought in bulk, and highlight the need to look beyond citation counts

Construction of financial constraint index, and the impact of financial constraint on firms’ cash holding and investment behavior: Evidence from UK manufacturing industry

This paper aims to construct a unique index of financial constraint for UK market and use the index to investigate the influence of financial constraint on UK firms’ cash holding and investment behavior. As for this purposes, all manufacturing listed firms’ data in UK during 2007 to 2015 are collected as the sample. By constructing the index, I found that the cash flow, cash ratio, leverage, and age are the key factors to explain the financial constraint. Moreover, by using the index into the further liquidity demand and investment demand model, I found that constrained firms have higher cash level and cash flow sensitivity of cash compared to unconstrained firms, and they have lower investment level and cash flow sensitivity of investment than unconstrained firms

An image is worth 1000 lies: adversarial transferability across prompts on vision-language models

Different from traditional task-specific vision models, recent large VLMs can readily adapt to different vision tasks by simply using different textual instructions, i.e., prompts. However, a well-known concern about traditional task-specific vision models is that they can be misled by imperceptible adversarial perturbations. Furthermore, the concern is exacerbated by the phenomenon that the same adversarial perturbations can fool different task-specific models. Given that VLMs rely on prompts to adapt to different tasks, an intriguing question emerges: Can a single adversarial image mislead all predictions of VLMs when a thousand different prompts are given? This question essentially introduces a novel perspective on adversarial transferability: cross-prompt adversarial transferability. In this work, we propose the Cross-Prompt Attack (CroPA). This proposed method updates the visual adversarial perturbation with learnable textual prompts, which are designed to counteract the misleading effects of the adversarial image. By doing this, CroPA significantly improves the transferability of adversarial examples across prompts. Extensive experiments are conducted to verify the strong cross-prompt adversarial transferability of CroPA with prevalent VLMs including Flamingo, BLIP-2, and InstructBLIP in various different tasks

Indirect measurement of infrared absorption spectrum through thermal emission of meta-cavity array

Controlling thermal emission is essential for various infrared spectroscopy applications. Metasurfaces can be utilized to control multiple degrees of freedom of thermal emission, enabling the compact thermal emission materials and devices. Infrared spectroscopy such as FTIR (Fourier transform infrared spectroscopy), usually requires external infrared radiation source and complex spectroscopic devices for absorption spectrum measurement, which hinders the implementation of integrated compact and portable measurement equipment. Measuring absorption spectrum through the thermal emission of pixelated thermal emitter array can facilitate the integration and miniaturization of measurement setup, which is highly demanded for on-chip spectroscopy applications. Here, we experimentally demonstrate an integrated technology that allows for indirect measurement of the absorption spectrum through the thermal emission of meta-cavity array. This indirect measurement method opens a new avenue for compact infrared spectroscopy analysis.Comment: 14 pages, 9 figure