Rapid synthesis of nanostructured porous silicon carbide from biogenic silica

Nanostructured silicon carbide (SiC) is an exceptional material with numerous applications, for example, in catalysis, biomedicine, high-performance composites, and sensing. In this study, a fast and scalable method of producing nanostructured SiC from plant materials by magnesiothermic reduction via self-propagating high-temperature synthesis (SHS) route was developed. The produced biogenic material possessed a high surface area above 200 m²/g with a SiC crystallite size below 10 nm, which has not been done previously by SHS. This method enables affordable synthesis of the material plant-based precursors in a reaction that only takes a few seconds, thereby paving a way for nanostructured SiC production in high volumes using renewable resources. The material was also functionalized with carboxylic acid and bisphosphonate moieties, and its use as metal adsorbent in applications such as wastewater remediation was demonstrated.     

Toward Rigorous Materials Production: New Approach Methodologies Have Extensive Potential to Improve Current Safety Assessment Practices

Advanced material development, including at the nanoscale, comprises costly and complex challenges coupled to ensuring human and environmental safety. Governmental agencies regulating safety have announced interest toward acceptance of safety data generated under the collective term New Approach Methodologies (NAMs), as such technologies/approaches offer marked potential to progress the integration of safety testing measures during innovation from idea to product launch of nanomaterials. Divided in overall eight main categories, searchable databases for grouping and read across purposes, exposure assessment and modeling, in silico modeling of physicochemical structure and hazard data, in vitro high‐throughput and high‐content screening assays, dose‐response assessments and modeling, analyses of biological processes and toxicity pathways, kinetics and dose extrapolation, consideration of relevant exposure levels and biomarker endpoints typify such useful NAMs. Their application generally agrees with articulated stakeholder needs for improvement of safety testing procedures. They further fit for inclusion and add value in nanomaterials risk assessment tools. Overall 37 of 50 evaluated NAMs and tiered workflows applying NAMs are recommended for considering safer‐by‐design innovation, including guidance to the selection of specific NAMs in the eight categories. An innovation funnel enriched with safety methods is ultimately proposed under the central aim of promoting rigorous nanomaterials innovation.     

Effects of High Temperature on the Pore Structure and Strength of Plain and Polypropylene Fiber Reinforced Cement Pastes

The effect of high temperature on the residual properties of plain and polypropylene fiber reinforced Portland cement paste was investigated. Plain Portland cement paste having water/cement ratio of 0.32 was exposed to the temperatures of 20, 50, 75, 100, 120, 150, 200, 300, 400, 440, 520, 600, 700, 800, and 1000°C. Paste with polypropylene fibers was exposed to the temperature of 20, 120, 150, 200, 300, 440, 520, and 700°C. Residual compressive and flexural strengths were measured and pore structure of the pastes was determined by mercury porosimetry. The total porosity of the pastes more than doubled when exposure temperature was increased from 20°C to 1000°C. The gradual heating coarsened the pore structure. The most notable coarsening of pore structure—together with strength loss—took place at exposure temperatures exceeding 600°C. At 600°C, the residual compressive capacity (f_c600°C/f_c20°C) was still over 50% of the original. Strength loss due to the increase of temperature was not linear. Polypropylene fibers produced a finer residual capillary pore structure, decreased compressive strengths, and improved residual flexural strengths at low temperatures. According to the tests, it seems that exposure temperatures from 50°C to 120°C can be as dangerous as exposure temperatures 400–500°C to the residual strength of cement paste produced by a low water cement ratio.     

The field comparison of three measuring techniques for evaluation of the surface dust level in ventilation ducts

This paper reports the comparison of three measuring methods for quantifying the amount of dust on the inner surface of ventilation ducts: 1) a vacuum test method; 2) a gravimetric tape method; and 3) an optical method. Thirteen recently constructed buildings were selected for the field test in the Helsinki metropolitan area. The dust samples in each method were all taken from the same location in the duct. Most of the ducts sampled had no residual oil originating from the manufacturing process. The mean amount of dust measured with the vacuum test method was 1.3 g/m2 and the range was < 0.1-8.4 g/m2. The mean surface dust level measured using the gravimetric tape method was slightly lower, i.e. 1.2 g/m2 (< 0.1-5.0 g/m2). The mean cleanliness level of the ducts was 15% (2-41%) using the optical method. The wide variations and differences in the results of the different methods were caused by the unequal distribution of dust on the duct surfaces.     

Detailed modeling of the kraft pulping chemistry: carbohydrate reactions

The article introduces a detailed model for carbohydrate chemistry in kraft pulping. This article is continuation to the modeling work carried out for hot water extraction and chemical pulp bleaching. The model includes galactoglucomannan, xylan, and cellulose acid–base equilibria, in addition to peeling, stopping, and alkaline hydrolysis reactions of the same carbohydrates, as well as hexenuronic acid formation and degradation reactions. The Arrhenius parameters were applied from the literature or regressed against experimental data in the present study. The model is very successful in predicting the experimental data of carbohydrate reactions during kraft pulping. Many features of the pulping-related model can be applied to specific fractionation chemistry considerations. The detailed knowledge on carbohydrates composition at any stage of pulping gives possibility for further development of biorefinery cases based on kraft pulping, such as biofuel and chemicals production.     

Rational modification of ligand-binding preference of avidin by circular permutation and mutagenesis

Chicken avidin is a key component used in a wide variety of biotechnological applications. Here we present a circularly permuted avidin (cpAvd4-->3) that lacks the loop between beta-strands 3 and 4. Importantly, the deletion of the loop has a positive effect on the binding of 4'-hydroxyazobenzene-2-carboxylic acid (HABA) to avidin. To increase the HABA affinity of cpAvd4-->3 even further, we mutated asparagine 118 on the bottom of the ligand-binding pocket to methionine, which simultaneously caused a significant drop in biotin-binding affinity. The X-ray structure of cpAvd4--> 3(N118M) allows an understanding of the effect of mutation to biotin-binding, whereas isothermal titration calorimetry revealed that the relative binding affinity of biotin and HABA had changed by over one billion-fold between wild-type avidin and cpAvd4-->3(N118M). To demonstrate the versatility of the cpAvd4-->3 construct, we have shown that it is possible to link cpAvd4-->3 and cpAvd5-->4 to form the dual-chain avidin called dcAvd2. These novel avidins might serve as a basis for the further development of self-organising nanoscale avidin building blocks.     

Towards gadget-free internet services: A roadmap of the Naked world

This paper presents a roadmap for the transition from current gadget-centric digital services towards a gadget-free services environment called the Naked world. The main idea of the Naked world is that all the services which are currently provided by gadgets will be provided by the infrastructure, thus no gadgets will be needed to use any kind of digital services. When a user in the Naked world intends to use a service, the infrastructure senses the user, the nearby intelligent surrounding launches an interactive user interface, performs identification through biometric identities, provides the service, and then closes the session when the user finishes the job. Therefore, the Naked world comprises highly intelligent and context-aware interactive environments. The vision of the Naked world is an evolution towards a user-friendly and ubiquitously available digital services, which is naturally bounded by the technological advancement. Henceforth, this paper presents the essential technologies and functional requirements along with the current and forthcoming novel technological concepts and challenges for the realization of the Naked world.     

Effect of Ultrafiltration on Anthocyanin and Flavonol Content of Black Currant Juice (Ribes nigrum L.)

This paper evaluates the efficiency of ultrafiltration and the effects of processing on the total anthocyanin and flavonol contents of black currant juice at chosen operational conditions. Ultrafiltration of black currant juices was carried out using Biomax 100?kDa polyethersulfone membrane. Ultrafiltration was used to process the juice prior concentration by reverse osmosis; with the aim to enhance the efficiency of the concentration process in terms of permeate flux. To avoid the fouling of the membrane, the juices were depectinized with Panzym Super E liquid enzyme preparation. The ultrafiltration was carried out at a transmembrane pressure of 2?bars and the operating temperature of 25?°C. The effect of processing on the valuable anthocyanin and flavonol content of the juices was evaluated based on the results of high-performance liquid chromatography analyses. The article includes detailed analyses of anthocyanin and flavonol compounds of the enzyme treated and ultrafiltered juice as compared with the original juice. The results indicate that, due to the enzymatic treatment, the valuable compound content of the juice increases. However, the ultrafiltration process resulted in a significant loss of a valuable content; 54% of total flavonol and 50% of total anthocyanins maintained in ultrafiltered juice when compared to the feed samples.     

HIBI Communication Network for System-on-Chip

This paper presents a communication network targeted for complex system-on-chip (SoC) and network-on-chip (NoC) designs. The Heterogeneous IP Block Interconnection (HIBI) aims at maximum efficiency and minimum energy per transmitted bit combined with quality-of-service (QoS) in transfers. Other features include support for hierarchical topologies with several clock domains, flexible scalability, and runtime reconfiguration of network parameters. HIBI is intended for integrating coarse-grain components such as intellectual property (IP) blocks that have size of thousands of gates.HIBI has been implemented in VHDL and SystemC and synthesized on several CMOS technologies and on FPGA. A 32-bit wrapper requires 5400 gates and runs with 315 MHz on 0.18 μ m technology which shows that only minimal area overhead is paid for the advanced features. The area and frequency results are well comparable to other NoC proposals.Furthermore, data transfers are shown to approach the maximum theoretical performance for protocol efficiency. HIBI network is accompanied with a design framework with tools for optimizing the system through automated design space exploration. Erno Salminen Tampere University of Technology (TUT), Finland.Currently he is working towards his PhD degree in the Institute of Digital and Computer Systems (DCS) at TUT. His main research interests are digital systems design and communication issues in SoCs. Tero KangasTampere University of Technology (TUT), Finland.Since 1999 he has been working as a research scientist in the Institute of Digital and Computer Systems (DCS) at TUT. Currently he is working towards his PhD degree and his main research topics are system architectures and SoC design methodologies in multimedia applications. Timo D. H?m?al?ainen Tampere University of Technology (TUT), Finland. He was nominated to full professor at TUT/Institute of Digital and Computer Systems in 2001. He heads the DACI research group that focuses on three main research areas: wireless sensor networks, high-performance multi-DSP and hardware based video encoding, and design flow tools for heterogeneous MP-SoC platforms. Jouni Riihi?mki Tampere University of Technology (TUT), Finland. Currently he is working as a senior design engineer at Nokia Technlogy Platforms. He is also working towards his PhD degree. His research interests include SoC design and verification methodologies. Vesa Lahtinen received his M.Sc. and Ph.D. from TUT in 1998 and 2004, respectively. In TUT, his main research areas were system-on-chips and their interconnects. Currently, Dr. Lahtinen is a Senior Research Engineer in the Computing Architectures Laboratory of Nokia Research Center (NRC) concentrating on architecture modeling and, specifically, memory architectures. Kimmo Kuusilinna Tampere University of Technology (TUT), Finland. His main research interests include system-level design and verification, on-chip interconnections, and parallel memories. Currently he is working as a senior research engineer at the Nokia Research Center.     

Ion beam shaping and downsizing of nanostructures

We report a new approach for progressive and well-controlled downsizing of nanostructures below the 10?nm scale. A low energetic ion beam (Ar(+)) is used for gentle surface erosion, progressively shrinking the dimensions with ～1?nm accuracy. The method enables shaping of the nanostructure geometry and polishing of the surface. The process is clean room/high vacuum compatible being suitable for various applications. Apart from technological advantages, the method enables the study of various size phenomena on the same sample between sessions of ion beam treatment.