Numerical modelling of the reinforced concrete beam shear failure

Shear failure of reinforced concrete members is a complex process, which depends on a huge number of different factors. It is less investigated compared to other types of failure. Modern numerical methods, including finite-element method, allow predicting complex behavior of different structures when loaded. This article deals with the detailed nonlinear analysis of the shear failure of the reinforced concrete beam, using Drucker-Prager yield criterion. The results generated based on the finite-element model, developed in ANSYS software, were compared to the results of a laboratory experiment. In addition, the main advantages and disadvantages of this approach were described. © Published under licence by IOP Publishing Ltd

Simple Preparation of Novel Metal-Containing Mesoporous Starches

Metal-containing mesoporous starches have been synthesized using a simple and efficient microwave-assisted methodology followed by metal impregnation in the porous gel network. Final materials exhibited surface areas >60 m2 g−1, being essentially mesoporous with pore sizes in the 10–15 nm range with some developed inter-particular mesoporosity. These materials characterized by several techniques including XRD, SEM, TG/DTA and DRIFTs may find promising catalytic applications due to the presence of (hydr)oxides in their composition

Environmental impact assessment of wheat straw based alkyl polyglucosides produced using novel chemical approaches

This paper evaluates and quantifies the environmental performance of alkyl polyglucosides sourced from wheat straw (WS-APG), a low-cost and low-ecological impact agricultural residue, compared to that of their commercial counterpart, which is sourced from palm kernel oil and wheat grain (PW-APG). Escalating pressure to consider the environmental sustainability of fossil derived surfactant consumption has driven biosurfactants to become the product of choice within the surfactant market, and a class of ‘plant’ based non-ionic surfactants called alkyl polyglucosides (APG) are particularly prevalent. However, the existing food based feedstock of APG such as coconut oil, palm oil, wheat and corn (in addition to being expensive) will potentially undermine the claimed ‘sustainability’ of the APG products (i.e. the ‘food vs. chemical’ issue). Here, we present the “cradle-to-gate” life cycle impact assessment of a suggested alternative, hybridised APG synthesis technique where the Fisher glycosidation method is supplemented by novel, green chemistry based techniques. This evaluation provides a quantitative insight into direct GHG intensity and other ecological impact indicators, including land use, waste generation and energy consumption. Upon evaluation, the wheat straw-derived pathway delivered GHG-emission savings in the range of 84–98%, compared to that of the palm kernel–wheat grain pathway. Waste generated from the production of unit mass of the product amounted to 0.43 kg and 10.73 kg per kg of WS-APG and PW-APG, respectively. In addition to the above mentioned facts, the ‘cradle–gate’ stages of WS-APG production were also found to consume relatively lower amounts of water and fossil-derived energy. In conclusion, of the two APG production pathways, the suggested ‘hybrid’ pathway using an agricultural residue, wheat straw, was found to be sustainable and to demonstrate better environmental performance

Lipid production through the single-step microwave hydrolysis of macroalgae using the oleaginous yeast Metschnikowia pulcherrima

Macroalgae (seaweeds) represent an emerging resource for food and the production of commodity and specialty chemicals. In this study, a single-step microwave process was used to depolymerise a range of macroalgae native to the United Kingdom, producing a growth medium suitable for microbial fermentation. The medium contained a range of mono- and polysaccharides as well as macro- and micronutrients that could be metabolised by the oleaginous yeast Metschnikowia pulcherrima. Among twelve macroalgae species, the brown seaweeds exhibited the highest fermentation potential, especially the kelp Saccharina latissima. Applying a portfolio of ten native M. pulcherrima strains, yeast growth kinetics, as well as production of lipids and 2-phenylethanol were examined, with productivity and growth rate being strain dependent. On the 2 L scale, 6.9 g L−1 yeast biomass – a yield of 0.14 g g−1 with respect to the supplied macroalgae – containing 37.2% (w/w) lipid was achieved through utilisation of the proteins, mono- and polysaccharides from S. latissima, with no additional enzymes. In addition, the yeast degraded a range of fermentation inhibitors released upon microwave processing at high temperatures and long holding times. As macroalgae can be cultured to food grade, this system offers a novel, potentially low-cost route to edible microbial oils as well as a renewable feedstock for oleochemicals

Simple, quick and green isolation of cannabinoids from complex natural product extracts using sustainable mesoporous materials (Starbon®)

The current process to purify cannabidiol (CBD) from C. sativa extract is long and intensive, requiring several steps such as winterification for 48 hours at 45°C and high-temperature, high vacuum distillation. These processes are capital intensive and generate large amounts of toxic solvent waste. In contrast, the solid phase extraction (SPE) methodology proposed herein will change the way CBD is obtained, doing so in a single step that is fast and reusable. Furthermore, the new process is simple and easily implemented and does not require any intensive operator training. Starbon® A300 was successfully employed as the stationary phase in SPE taking Cannabis sativa extract in hexane to selectively physisorb the cannabinoids onto the surface, followed by ethanol to bring about desorption at up to 93 (by GC-FID). A similar one pot system was also proven, using Fedora hemp stem dust as feedstock, with extraction and adsorption in supercritical CO2 followed by desorption in ethanol. © 2022 The Royal Society of Chemistr

Передвижные морские буровые платформы для поиска месторождений нефти и газа. Обзор

A Jack-Up platform can float and be transported, it can be elevated when it arrives on location and its legs will rest on the sea bed. After an appropriate and rigorous site assessment the unit will be ready for operation. Due to the compliant characteristics of the structural system difficult challenges must be overcome by designers and operators. Generally, these challenges are more complex than most offshore structures and the later section in this chapter related to the management of hazards endorses this comment. This article is an overview of the main characteristics of these mobile units. A modern Jack-Up can weigh up to 20,000 tonnes and be capable of operating in 150 m of water in a very harsh ocean environment. Jack-Up platforms are designed and constructed to satisfy the rules of classification societies and classification is a comprehensive verification procedure. In this respect they may be regarded as mobile units together with ships and other marine structures. The main structural features are associated with the hull and the legs and foundation. However, separate sections for Jack-Up structural design and foundation design have been included in the Jack-Up chapter. Transportation is a critical stage when the unit can become unstable, but elevating the structure and the process of jacking can also be problematic. Transportation has been considered as a separate section in this chapter and the examples of accidents as case studies demonstrate the dangers associated with the critical stages of operation. Consideration has been given to the use of high strength steel in this review, but sections related to Fatigue and to Fracture Mechanics have been provided separately in the Jack-Up chapter. The section related to Marine Warranty Survey aspects brings together many of the features of Jack-Up operations and the potential of Jack-Up risk and reliability studies for risk assessment of various operating stages has been explored in the Reliability section within this chapter.Передвижная морская буровая платформа может плавать и перевозиться, ее можно поднимать, когда она прибывает на место, и ее ноги будут опираться на морское дно. После тщательного обследования конструкции и площадки установки, соответствующей и строгой оценки площадки буровая платформа готова к работе. Конструкторы и монтажники должны преодолеть и разрешить все возникающие проблемы установки буровой платформы. В этой статье рассмотрены основные характеристики этих передвижных конструкций. Вес современных передвижных морских буровых платформ достигает 20 000 тонн и они способны работать на глубинах до 150 м в суровых океанских условиях. Морские буровые платформы проектируются и строятся в соответствии со строгими положениями норм, а комплексная процедура проверки их соответствия нормативным требованиям является сложной задачей. В этом отношении они могут быть отнесены к категории морских судов. Основными конструкциями морских буровых платформ являются корпус, опоры и основание. Наиболее опасной ситуацией является передвижение морской буровой платформы, когда могут нарушиться требования общей устойчивости конструкции, однако в процессе ее подъема также могут возникнуть опасные ситуации. Стадия передвижения рассмотрена в отдельном разделе статьи, где показаны различные опасные случаи. Рассмотрены вопросы применения высокопрочных сталей. Вопросы усталостной прочности и механики разрушения рассмотрены отдельно. Отдельный раздел посвящен анализу риска и надежности в процессе установки морских буровых платформ

Bio-based carbonaceous composite materials from epoxidised linseed oil, bio-derived curing agent and starch with controllable functionality

Development of biomass-derived materials using sustainable practices has been one of the major scientific aims over the last few decades. A new class of bio-derived nanocomposite derived from epoxidised linseed oil, a bio-derived crosslinker and a starch based carbonaceous mesoporous material (Starbon®) has been developed. The use of Starbons® technology enables the incorporation of carbonaceous materials with tuneable surface functionality (from hydrophilic to hydrophobic). The resulting composite demonstrated good thermal stability up to 300 °C, good low temperature modulus, flexibility and uniformity, as demonstrated by TGA, DMA and SEM studies, respectively. Furthermore, the thermoset composites' swelling behaviour in solvents with a high polar index through to non-polar ones was investigated, revealing initially that non polar solvents have a greater impact on swelling than polar solvents and that in all cases the addition of filler reduces the extent of swelling. The inclusion of this carbonaceous material with hierarchical pore structure and high BET surface area may further aid the use of such composites in membrane separation applications

Conventional and microwave-assisted pyrolysis of biomass under different heating rates

Biomass was subjected to conventional and microwave pyrolysis, to determine the influence of each process on the yield and composition of the derived gas, oil and char products. The influence of pyrolysis temperature and heating rate for the conventional pyrolysis and the microwave power was investigated. Two major stages of gas release were observed during biomass pyrolysis, the first being CO/CO and the second one CH/H. This two-stage gas release was much more obvious for the conventional pyrolysis. While similar yield of liquid was obtained for both cases of conventional and microwave pyrolysis (∼46 wt.%), higher gas yield was produced for the conventional pyrolysis; it is suggested that microwave pyrolysis is much faster. When the heating rate was increased, the peak release of CO and CO was moved to higher reaction temperature for both conventional (500 °C) and microwave pyrolysis (200 °C). The production of CH and H were very low at a conventional pyrolysis temperature of 310 °C and microwave pyrolysis temperature of 200 °C (600 and 900 W). However, at higher heating rate of microwave pyrolysis, clear release of CH was observed. This work tentatively demonstrates possible connections and difference for biomass pyrolysis using two different heating resources (conventional and microwave heating)