Hasil untuk "Chemical engineering"

Song Bai, Ning Zhang, Chao Gao et al.

Abstract Defect engineering in photocatalytic materials has been proven as a versatile approach to maneuver their performance in solar-to-chemical energy conversion. In this article, the state-of-the-art progress on the defect-engineered photocatalytic materials is reviewed. We first give the critical classifications for defects in photocatalysts. Then various strategies for fabricating defects in photocatalytic materials are summarized together with their characterization techniques. As a focus, the promotion of three basic steps in photocatalysis, including light absorption, charge transfer and separation, and surface catalytic reaction by defect engineering is discussed in detail. Moreover, some other important functions of defects in photocatalysis are introduced in the article, followed by the discussion on some recent advancements of defective photocatalytic materials in energy-related applications. Finally, the future opportunities and challenges regarding defect engineering in photocatalysis are presented to highlight the development directions of this research field.

J. Zoppe, Nariye Cavusoglu Ataman, Piotr Mocny et al.

Qijie Liang, Qian Zhang, Xiaoxu Zhao et al.

Atomic defects, being the most prevalent zero-dimensional topological defects, are ubiquitous in a wide range of 2D transition-metal dichalcogenides (TMDs). They could be intrinsic, formed during the initial sample growth, or created by postprocessing. Despite the majority of TMDs being largely unaffected after losing chalcogen atoms in the outermost layer, a spectrum of properties, including optical, electrical, and chemical properties, can be significantly modulated, and potentially invoke applicable functionalities utilized in many applications. Hence, controlling chalcogen atomic defects provides an alternative avenue for engineering a wide range of physical and chemical properties of 2D TMDs. In this article, we review recent progress on the role of chalcogen atomic defects in engineering 2D TMDs, with a particular focus on device performance improvements. Various approaches for creating chalcogen atomic defects including nonstoichiometric synthesis and postgrowth treatment, together with their characterization and interpretation are systematically overviewed. The tailoring of optical, electrical, and magnetic properties, along with the device performance enhancement in electronic, optoelectronic, chemical sensing, biomedical, and catalytic activity are discussed in detail. Postformation dynamic evolution and repair of chalcogen atomic defects are also introduced. Finally, we offer our perspective on the challenges and opportunities in this field.

D. Sahoo, T. Biswal

Alginate is a polysaccharide of natural origin, which shows outstanding properties of biocompatibility, gel forming ability, non-toxicity, biodegradability and easy to process. Due to these excellent properties of alginate, sodium alginate, a hydrogel form of alginate, oxidized alginate and other alginate based materials are used in various biomedical fields, especially in drug delivery, wound healing and tissue engineering. Alginate can be easily processed as the 3D scaffolding materials which includes hydrogels, microcapsules, microspheres, foams, sponges, and fibers and these alginate based bio-polymeric materials have particularly used in tissue healing, healing of bone injuries, scars, wound, cartilage repair and treatment, new bone regeneration, scaffolds for the cell growth. Alginate can be easily modified and blended by adopting some physical and chemical processes and the new alginate derivative materials obtained have new different structures, functions, and properties having improved mechanical strength, cell affinity and property of gelation. This can be attained due to combination with other different biomaterials, chemical and physical crosslinking, and immobilization of definite ligands (sugar and peptide molecules). Hence alginate, its modified forms, derivative and composite materials are found to be more attractive towards tissue engineering. This article provides a comprehensive outline of properties, structural aspects, and application in tissue engineering.

B. Finlayson

Ling Luo, Zhihao Yang, Pei Yang et al.

M. Benedict

Junqi Zhang, Feng Li, Dingyuan Liu et al.

The excessive consumption of fossil fuels causes massive emission of CO2, leading to climate deterioration and environmental pollution. The development of substitutes and sustainable energy sources to replace fossil fuels has become a worldwide priority. Bio-electrochemical systems (BESs), employing redox reactions of electroactive microorganisms (EAMs) on electrodes to achieve a meritorious combination of biocatalysis and electrocatalysis, provide a green and sustainable alternative approach for bioremediation, CO2 fixation, and energy and chemicals production. EAMs, including exoelectrogens and electrotrophs, perform extracellular electron transfer (EET) (i.e., outward and inward EET), respectively, to exchange energy with the environment, whose rate determines the efficiency and performance of BESs. Therefore, we review the synthetic biology strategies developed in the last decade for engineering EAMs to enhance the EET rate in cell-electrode interfaces for facilitating the production of electricity energy and value-added chemicals, which include (1) progress in genetic manipulation and editing tools to achieve the efficient regulation of gene expression, knockout, and knockdown of EAMs; (2) synthetic biological engineering strategies to enhance the outward EET of exoelectrogens to anodes for electricity power production and anodic electro-fermentation (AEF) for chemicals production, including (i) broadening and strengthening substrate utilization, (ii) increasing the intracellular releasable reducing equivalents, (iii) optimizing c-type cytochrome (c-Cyts) expression and maturation, (iv) enhancing conductive nanowire biosynthesis and modification, (v) promoting electron shuttle biosynthesis, secretion, and immobilization, (vi) engineering global regulators to promote EET rate, (vii) facilitating biofilm formation, and (viii) constructing cell-material hybrids; (3) the mechanisms of inward EET, CO2 fixation pathway, and engineering strategies for improving the inward EET of electrotrophic cells for CO2 reduction and chemical production, including (i) programming metabolic pathways of electrotrophs, (ii) rewiring bioelectrical circuits for enhancing inward EET, and (iii) constructing microbial (photo)electrosynthesis by cell-material hybridization; (4) perspectives on future challenges and opportunities for engineering EET to develop highly efficient BESs for sustainable energy and chemical production. We expect that this review will provide a theoretical basis for the future development of BESs in energy harvesting, CO2 fixation, and chemical synthesis.

Anthony Chidi Ezika, Williams Kehinde Kupolati, Emmanuel Rotimi Sadiku et al.

The current challenge in energy storage technologies lies in identifying efficient electrode materials for Magnesium-ion (Mg-ion) batteries, motivating the exploration of the energy storage capabilities of Polypyrrole-MXene (Ti2CO2) nanocomposites as a potential solution to enhance battery performance. Hence, in this paper, quantum mechanical simulations were employed to examine the capability of energy storage of Polypyrrole-MXene (Ti2CO2) filled nanocomposite. The electronic structures, adsorption energies, and adsorption site of Mg@PPy/MXene (Ti2CO2) nanocomposite were investigated. The results reveal that Mg-ions on MXene/PPy nanocomposite have a very high adsorption energy of -0.84 eV. The distance of Mg-ion adsorption from the MXene’s surface at the bridge site is 2.75 Å. However, its distance from the PPy is considerably farther at 2.83 Å. The electron difference study, using the charge transfer analysis, revealed that physisorption is the dominating adsorption mechanism for the Mg-ion in the system. The electrode's propensity to transport electrons during the electrochemical reaction is shown by the projected density of state (PDOS), and its energy bandgap is 0.05. Consequently, the MXene (Ti2CO2) /PPy nanocomposite might be used as an Mg-ion electrode in battery applications.

Adel Beig Babaei, Arash Dara, Hanieh Sadat Taheri

This study examines the effectiveness of a composite material made from reduced graphene oxide (rGO) and magnetic nanoparticles for the adsorption of heavy metals from wastewater, addressing a critical environmental issue as heavy metal pollution poses significant risks to human health. Traditional water treatment methods often fail to adequately remove these persistent contaminants. The composite takes advantage of graphene's high surface area and adsorption capacity, while the magnetic nanoparticles facilitate easy separation and reusability of the adsorbent. Characterization techniques such as X-ray diffraction (XRD) and Raman spectroscopy were employed to confirm the composite's structural integrity and the presence of rGO, highlighting its functional properties. The study's focus lay on investigating mercury removal efficiency across varying pH levels (1–6), temperatures (25 °C), mercury concentrations (10 g/L), adsorbent amounts (0.01–0.05 g/L), and contact times (120–360 s). The findings indicated that optimal mercury adsorption occurred at pH 6, with a 100 s contact time, 25 °C, and 0.05 g of adsorbent. The maximum mercury removal achieved was quantified at 9.15 µg/L, demonstrating the potential of iron nanoparticle-magnetized nano graphene oxide as an efficient and sustainable solution for heavy metal remediation in wastewater treatment applications. The results obtained showed that graphene oxide magnetized with iron nanoparticles can be effectively used to remove mercury from water and wastewater samples.Overall, this research highlights a promising pathway towards addressing the pressing challenge of water pollution with heavy metals.

B. Tiss, D. Martínez-Martínez, C. Mansilla et al.

Yernazar Bolat, Iain Murray, Yifei Ren et al.

The growing adoption of IoT applications has led to increased use of low-power microcontroller units (MCUs) for energy-efficient, local data processing. However, deploying deep neural networks (DNNs) on these constrained devices is challenging due to limitations in memory, computational power, and energy. Traditional methods like cloud-based inference and model compression often incur bandwidth, privacy, and accuracy trade-offs. This paper introduces a novel Decentralized Distributed Sequential Neural Network (DDSNN) designed for low-power MCUs in Tiny Machine Learning (TinyML) applications. Unlike the existing methods that rely on centralized cluster-based approaches, DDSNN partitions a pre-trained LeNet across multiple MCUs, enabling fully decentralized inference in wireless sensor networks (WSNs). We validate DDSNN in a real-world predictive maintenance scenario, where vibration data from an industrial pump is analyzed in real-time. The experimental results demonstrate that DDSNN achieves 99.01% accuracy, explicitly maintaining the accuracy of the non-distributed baseline model and reducing inference latency by approximately 50%, highlighting its significant enhancement over traditional, non-distributed approaches, demonstrating its practical feasibility under realistic operating conditions.

Sulayman Khan, Yunus Azakli, William Pulfrey et al.

A microalloyed (MA) steel, combined with titanium diboride (TiB₂), was utilised to create a unique steel matrix composite (SMC), enhancing the modulus of the MA steel while also improving its strength. Through thermomechanical processing stages, including hot rolling and plane-strain compression (PSC) testing, followed by various final cooling methods, a cooling rate of 0.1 °C/s was identified as the most effective for achieving a ferrite–pearlite microstructure, which is suitable for toughness and ductility. With TiB₂ reinforcement successfully incorporated via Fe-Ti and Fe-B additions during vacuum induction melting (VIM), it was observed that the TiB₂ particles were homogeneously dispersed in both 5% and 7.5% nominal volume fraction additions, exhibiting faceted and hexagonal morphology. TiB₂ was found to exert a grain-pinning effect on recrystallised austenite at 1050 °C, as evidenced by the retention of grain orientation from hot rolling, in contrast to the MA steel deformed without the composite reinforcement. Increasing the volume fraction of TiB₂ improved the stiffness and strength of both composite alloys, verified through mechanical testing.

M. Mowbray, M. Vallerio, Carlos Pérez-Galván et al.

Understand and optimize industrial processes via machine learning and chemical engineering principles.

Matteo Iaiani, Alessandro Tugnoli, Valerio Cozzani

The increasing interconnectivity with external networks and the higher reliance on digital systems make chemical and process industries, including waste and drinking water treatment plants, more vulnerable to cyber-attacks. Historical evidence shows that these attacks have the potential to cause events with severe consequences on property, people, and the surrounding environment, posing a serious threat. While the risks deriving from the malicious manipulation of the Basic Process Control System (BPCS) and the Safety Instrumented System (SIS) in chemical and Oil&Gas facilities have been systematically analysed in the available literature, including previous works of the Authors, the analysis of the consequences of cyber-attacks to drinking water treatment plants has not been conducted to date. To fill this gap, in the present study the methodology POROS 2.0 (Process Operability Analysis of Remote manipulations through the cOntrol System) developed by the Authors was applied to a drinking water treatment plant, providing valuable insights on possible critical scenarios originated by cyber-attacks in these facilities.

LI Peixuan, GE Xinsheng, TIAN Yadong et al.

Purposes To investigate the influence of different tamping methods on the reinforcement effect of sand dynamic compaction, this research has been done from the perspective of soil stress distribution characteristics. Methods The dynamic compaction model test was carried out in the outdoor field to monitor the vertical and radial soil pressures in the soil and falling weight acceleration during tamping process, and the displacements in the soil were analyzed by numerical simulation method. Findings It is concluded that in the construction of dynamic compaction method, the vertical soil pressure waveform is the shock wave waveform or the vibration attenuation wave shape, and the radial earth pressure waveform is the impact waveform; There are two reinforcement modes in the process of dynamic compaction, the soil under tamping point is mainly vertically compacted, while the soil side of tamping point also has significant radial compaction; At the same level of dynamic compaction, heavy falling weight is suitable for deep soil and radial soil reinforcement, while light falling weight is suitable for rapid reinforcement of shallow soil. Conclusions The research results have a certain guiding significance for the selection of tamping methods of the same energy level dynamic compaction.

Dániel Gosztola, Peter Grubits, János Szép et al.

The growing importance of numerical simulations in the welding industry stems from their ability to enhance structural performance and sustainability by ensuring optimal manufacturing conditions. The use of the finite element method (FEM) allows for detailed and precise calculations of the mechanical and material changes caused by the welding process. Acquiring knowledge of these parameters not only serves to augment the quality of the manufacturing process but also yields consequential benefits, such as reducing adverse effects. Consequently, the enhancement of structural performance and prolonged lifespan becomes achievable, aligning with overarching sustainability goals. To achieve this goal, this paper utilizes numerical simulations of welding processes based on experimental tests, with a specific focus on analyzing temperatures generated within the structures. In the finite element analysis (FEA), a total of 12 welding cycles were systematically modeled to align with experimental conditions, incorporating cooling intervals, preheating considerations, and the relevant section of the connecting concrete structure with studs. The outcomes of this research exemplify the potential of numerical simulation in the welding industry, demonstrating a diverse range of results achieved through FEA to enhance the quality of structures within the context of sustainability.

Thais N. Guerrero, Ruth M. Fisher, Ademir A. Prata et al.

The beneficial reuse and recovery of biosolids is an attractive option instead of disposal. However, odour emissions present significant challenges to land application of biosolids, increasing operational costs and reducing community acceptance. This study aimed to assess the influence of conveying and storage conditions in wastewater treatment plants on the sensory impact from biosolids. For sensory assessment, samples of anaerobically digested biosolids were collected after centrifuge and during storage out-loading. The emissions were extracted over 15 days using a dynamic flux chamber and sensory analysis conducted using an ODP coupled to a TD-GC-MS. Odour descriptors and intensities (from 1 – weak to 4 – strong) were evaluated by expert panellists, providing insights into the sensory aspects of odour emissions. The ODP results showed variations in the number of occurrences, intensity and modified frequency of odour events across the stages of wastewater solids processing and laboratory storage. Conveying could potentially impact the release of volatile compounds due to the mechanical agitation that can aerate and disturb the structure and surface of the biosolids. On the other hand, storage can accelerate biological and chemical processes as a result of the development of anaerobic conditions leading to subsequent odour generation. The interplay between wastewater treatment processes and odour emissions is complex and requires targeted strategies. The application of sensorial analysis contributes to valuable insights into understanding and managing odour emissions in wastewater treatment plants, offering potential avenues for optimizing operational parameters to benefit biosolids reuse initiatives. Keywords: Wastewater sludge; Anaerobic digestion; Biosolids; Beneficial reuse; Land application; Gaseous emissions; Sensory emissions; Sensory analysis; Odour detection port.

Qingji Zhang, Xiaomei Chao, Yeman Tu et al.

Abstract This study investigates the relationship between labor values and two forms of envy—benign and malicious—as well as the potential mediating role of mindfulness using a mindfulness reperceiving model. Two thousand three hundred sixty three Chinese teenagers participated in a longitudinal study over an eight-month period, completing questionnaires measuring labor values, benign envy, malicious envy, and mindfulness. The cross-sectional data showed that labor values had an immediate negative effect on malicious envy, with mindfulness partially mediating this relationship. Additionally, labor values had an immediate positive effect on benign envy, but mindfulness did not mediate this relationship. Longitudinal data analysis revealed that the delayed effect of labor values on later benign/malicious envy was similar to its immediate effect. However, mindfulness only played a mediating role in the relationship between labor values and later malicious envy. Cross-gender stability was found in both the immediate effect model and the delayed effect model. Overall, this study sheds light on the influence of labor values on the development of social emotions and the potential mediating role of mindfulness in the Chinese cultural context.

Ceren Sagdic-Oztan, Andreas Koschella, Thomas Heinze et al.

Bacterial cellulose has superior physical and chemical properties, biocompatibility, and purity. However, the high production cost obstructs the common use of this polymer. This study investigated the efficiency of olive pomace, an important by-product of olive oil industry in Turkey, as a carbon source for Novacetimonas hansenii. Olive pomace pretreatment with 1% H3PO4 was followed by enzymatic hydrolysis. The maximal reducing sugar concentration upon enzymatic process was 9.3 g/L with 1 enzyme: 6 substrate (dry matter) ratio. After incubation in the growth media prepared with the obtained reducing sugar as carbon source, the highest bacterial cellulose production was 0.68 g/L. Structural analysis indicated that bacterial cellulose from the enzymatic media and the conventional Hestrin-Schramm medium possess similar characteristics. The present work provides a favourable method to reduce the cost of bacterial cellulose production.