Hasil untuk "Chemical engineering"

Junmin Zhu, R. Marchant

Bo Hu, Kan Wang, Liheng Wu et al.

Junmin Zhu

Changqin Ding, Anwei Zhu, Yang Tian

Heungsoo Shin, S. Jo, A. Mikos

J. Mills

D. Voiry, A. Goswami, R. Kappera et al.

J. Gaitzsch, Xinshu Huang, B. Voit

M. F. Cardinal, Emma Vander Ende, Ryan A. Hackler et al.

Surface-enhanced Raman scattering (SERS) spectroscopy has evolved into a cross-disciplinary analytical technique by unveiling relevant chemical, biological, material, and structural information. The focus of this review is on two critical properties for successfully expanding applications of SERS spectroscopy: quality of the plasmonic substrate and molecule localization to the substrate. In this review, we discuss recent work on quantifying SERS distance dependence, key factors for substrate characterization and performance evaluation, expansion of SERS applications through substrate development for UV plasmonics and short-distance capture strategies for optimizing analyte-surface structures. After surveying the recent developments of these seemingly disparate fields, we suggest new research directions that may originate from a synergistic blend of all the herein discussed topics. Finally, we discuss major challenges and open questions related to the application of SERS for understanding of chemical processes at the nanoscale, with special interest on in situ catalysts and biosensing.

Magezi K. Mabaso, Evans M. Chirwa, Shepherd M. Tichapondwa

The high concentration of heavy metals in wastewater highlights the urgent need to explore alternative treatment methods. Partially treated wastewater with elevated heavy metal levels can have severe environmental consequences, ultimately affecting the food chain. This study evaluates the effectiveness of bio-phytoremediation in treating heavy metal-contaminated wastewater using perennial grasses. The research analyzed one-year average effluent results for Pb and Cd, comparing their removal efficiencies at an initial concentration of 10ppm after introducing Vetiver grass (Chrysopogon zizanioides) and Elephant grass (Pennisetum purpurem). The compliance levels of different remediation approaches were assessed against South African wastewater discharge limits and World Health Organization (WHO) guidelines. Various remediation methods were considered, with a particular focus on bio-phytoremediation using selected grass species to remove heavy metals from contaminated wastewater. The findings indicated that Vetiver grass demonstrated a higher removal efficiency for Pb compared to Cd.

M. R. Du, T. D. Xuan, Z. F. Chen et al.

Abstract This study developed a novel high-brisance emulsion explosive containing sodium borohydride (NaBH4). The effects of NaBH4 content on the performance of the emulsion explosive were investigated using methods such as brisance, detonation velocity, air shock wave analysis, density measurement, and theoretical calculations. And the thermal decomposition characteristics of emulsion explosives samples were investigated using thermogravimetric (TG) experiments. The results indicate that as the NaBH4 content increases, the explosive density initially increases and then decreases, the detonation velocity gradually decreases, the explosive heat continuously increases, and the explosion volume first increases slightly and then decreases. Brisance, influenced by multiple factors including density, detonation velocity, explosive heat, and explosion volume, also shows a trend of first increasing and then decreasing. When the NaBH4 content is 5%, the brisance reaches its maximum value (26.3 mm), representing a 66.5% improvement compared to conventional emulsion explosives and surpassing existing high-brisance emulsion explosives. Furthermore, with increasing NaBH4 content, the peak overpressure of the air shock wave initially decreases and then increases. The TG and derivative thermogravimetry (DTG) curves of all samples exhibit consistent trends. Under the same heating rate, the addition of NaBH4 raises the initial decomposition temperature of the emulsion explosive.

Jie Jiang, T. Xu, Junpeng Lu et al.

Two-dimensional (2D) materials have attracted increasing interests in the last decade. The ultrathin feature of 2D materials makes them promising building blocks for next-generation electronic and optoelectronic devices. With reducing dimensionality from 3D to 2D, the inevitable defects will play more important roles in determining the properties of materials. In order to maximize the functionality of 2D materials, deep understanding and precise manipulation of the defects are indispensable. In the recent years, increasing research efforts have been made on the observation, understanding, manipulation, and control of defects in 2D materials. Here, we summarize the recent research progress of defect engineering on 2D materials. The defect engineering triggered by electron beam (e-beam), plasma, chemical treatment, and so forth is comprehensively reviewed. Firstly, e-beam irradiation-induced defect evolution, structural transformation, and novel structure fabrication are introduced. With the assistance of a high-resolution electron microscope, the dynamics of defect engineering can be visualized in situ. Subsequently, defect engineering employed to improve the performance of 2D devices by means of other methods of plasma, chemical, and ozone treatments is reviewed. At last, the challenges and opportunities of defect engineering on promoting the development of 2D materials are discussed. Through this review, we aim to build a correlation between defects and properties of 2D materials to support the design and optimization of high-performance electronic and optoelectronic devices.

M. Kreutzer, F. Kapteijn, J. Moulijn et al.

Min Jin, Junli Shi, Wenzhen Zhu et al.

In addition to proteins and nucleic acids, polysaccharides are an important type of biomacromolecule widely distributed in plants, animals, and microorganisms. Polysaccharides are considered as promising biomaterials due to their significant bioactivities, natural abundance, immunoactivity, and chemical modifiability for tissue engineering (TE) applications. Due to the similarities of the biochemical properties of polysaccharides and the extracellular matrix of human bodies, polysaccharides are increasingly recognized and accepted. Furthermore, the degradation behavior of these macromolecules is generally nontoxic. Certain delicate properties, such as remarkable mechanical properties and tunable tissue response, can be obtained by modifying the functional groups on the surface of polysaccharide molecules. The applications of polysaccharide-based biomaterials in the TE field have been growing intensively in recent decades, for example, bone/cartilage regeneration, cardiac regeneration, neural regeneration, and skin regeneration. This review summarizes the main essential properties of polysaccharides, including their chemical properties, crosslinking mechanisms, and biological properties, and focuses on the association between their structures and properties. The recent progress in polysaccharide-based biomaterials in various TE applications is reviewed, and the prospects for future studies are addressed as well. We intend this review to offer a comprehensive understanding of and inspiration for the research and development of polysaccharide-based materials in TE. Impact statement Polysaccharides are promising biomaterials due to their significant bioactivities, natural abundance, immunoactivity, and chemical modifiability for tissue engineering (TE) applications. As an important natural macromolecule, polysaccharide has attracted much attention both in academia and industry for several biomedical applications. Compared with synthetic materials, polysaccharides have unique biological properties; it is self-evident that polysaccharides will always be the research hotspot in fabricating various biomaterials for different TE. However, most researches about polysaccharides-based materials are still far from practical treatment. This review summarizes the main essential properties of polysaccharides, providing the basic information about chemical properties, crosslinking mechanisms, and biological properties. Recent researches about design and fabrication of polysaccharides-based materials are summarized.

Kathiresan Subramanian, Kagne Suresh

The administration of rural effluent is essential due to the scarcity of resources and infrastructure, which exacerbates health hazards and environmental degradation. Decentralised wastewater treatment (DWT) is a system that reduces the transportation costs and environmental impact by recycling wastewater for agricultural and other purposes. This study suggests a single system DWT technique that integrates natural and artificial systems to enhance rural sustainability. The system employs an Anaerobic Baffled Reactor (ABR) for the initial decomposition of organic matter, a solar-powered disinfection device, and constructed wetlands (CW) for the secondary treatment and nutrient removal. The system is cost-effective and simple to deploy by utilizing renewable energy and local components. The system satisfied local environmental criteria by reducing biochemical oxygen demand (BOD) by 85 %, total suspended solids (TSS) by 90 %, and infections by 99.9 %, as demonstrated by a pilot study conducted in a rural community. Users and administrators were impressed by the system's simplicity and ease of maintenance. Sustainability and ownership were enhanced through community involvement in design and execution. The results indicate that this DWT technique, considered a scalable and adaptive wastewater management solution, has the potential to enhance the quality of water and the health of rural environments. To enhance the sustainability and effectiveness of the system, future research will expand the number of system components and examine alternative applications, such as nitrogen recovery and greywater recycling. This study demonstrates that rural communities may address wastewater treatment challenges by employing a decentralized approach that capitalizes on community engagement and local resources. This strategy also has a positive impact on public health and the environment over time.

A. Abdel-Mawgoud, Kelly A. Markham, Claire M. Palmer et al.

The nonconventional, oleaginous yeast, Yarrowia lipolytica is rapidly emerging as a valuable host for the production of a variety of both lipid and nonlipid chemical products. While the unique genetics of this organism pose some challenges, many new metabolic engineering tools have emerged to facilitate improved genetic manipulation in this host. This review establishes a case for Y. lipolytica as a premier metabolic engineering host based on innate metabolic capacity, emerging synthetic tools, and engineering examples. The metabolism underlying the lipid accumulation phenotype of this yeast as well as high flux through acyl-CoA precursors and the TCA cycle provide a favorable metabolic environment for expression of relevant heterologous pathways. These properties allow Y. lipolytica to be successfully engineered for the production of both native and nonnative lipid, organic acid, sugar and acetyl-CoA derived products. Finally, this host has unique metabolic pathways enabling growth on a wide range of carbon sources, including waste products. The expansion of carbon sources, together with the improvement of tools as highlighted here, have allowed this nonconventional organism to act as a cellular factory for valuable chemicals and fuels.

J. Baumann, Molly S. Adam, J. Wood

Spray drying is a versatile technology that has been applied widely in the chemical, food, and, most recently, pharmaceutical industries. This review focuses on engineering advances and the most significant applications of spray drying for pharmaceuticals. An in-depth view of the process and its use is provided for amorphous solid dispersions, a major, growing drug-delivery approach. Enhanced understanding of the relationship of spray-drying process parameters to final product quality attributes has made robust product development possible to address a wide range of pharmaceutical problem statements. Formulation and process optimization have leveraged the knowledge gained as the technology has matured, enabling improved process development from early feasibility screening through commercial applications. Spray drying's use for approved small-molecule oral products is highlighted, as are emerging applications specific to delivery of biologics and non-oral delivery of dry powders. Based on the changing landscape of the industry, significant future opportunities exist for pharmaceutical spray drying. Expected final online publication date for the Annual Review of Chemical and Biomolecular Engineering, Volume 12 is June 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Tong Un Chae, J. Ahn, Yoo-Sung Ko et al.

Microbial production of chemicals and materials from renewable carbon sources is becoming increasingly important to help establish sustainable chemical industry. In this paper, we review current status of metabolic engineering for the bio-based production of linear and saturated dicarboxylic acids and diamines, important platform chemicals used in various industrial applications, especially as monomers for polymer synthesis. Strategies for the bio-based production of various dicarboxylic acids having different carbon numbers including malonic acid (C3), succinic acid (C4), glutaric acid (C5), adipic acid (C6), pimelic acid (C7), suberic acid (C8), azelaic acid (C9), sebacic acid (C10), undecanedioic acid (C11), dodecanedioic acid (C12), brassylic acid (C13), tetradecanedioic acid (C14), and pentadecanedioic acid (C15) are reviewed. Also, strategies for the bio-based production of diamines of different carbon numbers including 1,3-diaminopropane (C3), putrescine (1,4-diaminobutane; C4), cadaverine (1,5-diaminopentane; C5), 1,6-diaminohexane (C6), 1,8-diaminoctane (C8), 1,10-diaminodecane (C10), 1,12-diaminododecane (C12), and 1,14-diaminotetradecane (C14) are revisited. Finally, future challenges are discussed towards more efficient production and commercialization of bio-based dicarboxylic acids and diamines.

T. Erb, Patrik R. Jones, A. Bar‐Even

Metabolic engineering aims at modifying the endogenous metabolic network of an organism to harness it for a useful biotechnological task, for example, production of a value-added compound. Several levels of metabolic engineering can be defined and are the topic of this review. Basic 'copy, paste and fine-tuning' approaches are limited to the structure of naturally existing pathways. 'Mix and match' approaches freely recombine the repertoire of existing enzymes to create synthetic metabolic networks that are able to outcompete naturally evolved pathways or redirect flux toward non-natural products. The space of possible metabolic solution can be further increased through approaches including 'new enzyme reactions', which are engineered on the basis of known enzyme mechanisms. Finally, by considering completely 'novel enzyme chemistries' with de novo enzyme design, the limits of nature can be breached to derive the most advanced form of synthetic pathways. We discuss the challenges and promises associated with these different metabolic engineering approaches and illuminate how enzyme engineering is expected to take a prime role in synthetic metabolic engineering for biotechnology, chemical industry and agriculture of the future.

D. Williams

Lehigh has a diverse group of faculty members with strong, primary interest in polymer science and engineering. In order to provide better opportunities for courses and research in this interdisciplinary field, activities are coordinated through the Center for Polymer Science and Engineering (CPSE), and its academic Polymer Education Committee. Polymer faculty from traditional departments of chemical engineering, chemistry, materials science and engineering, physics, and mechanical engineering and mechanics, are participants of the CPSE.