Hasil untuk "Chemical engineering"

Soroosh Derakhshanfar, R. Mbeleck, Kaige Xu et al.

3D printing, an additive manufacturing based technology for precise 3D construction, is currently widely employed to enhance applicability and function of cell laden scaffolds. Research on novel compatible biomaterials for bioprinting exhibiting fast crosslinking properties is an essential prerequisite toward advancing 3D printing applications in tissue engineering. Printability to improve fabrication process and cell encapsulation are two of the main factors to be considered in development of 3D bioprinting. Other important factors include but are not limited to printing fidelity, stability, crosslinking time, biocompatibility, cell encapsulation and proliferation, shear-thinning properties, and mechanical properties such as mechanical strength and elasticity. In this review, we recite recent promising advances in bioink development as well as bioprinting methods. Also, an effort has been made to include studies with diverse types of crosslinking methods such as photo, chemical and ultraviolet (UV). We also propose the challenges and future outlook of 3D bioprinting application in medical sciences and discuss the high performance bioinks.

Yunpei Zhu, Chunxia Guo, Yao Zheng et al.

Jia-nan Liu, Wenbo Bu, Jianlin Shi

Chong Wang, Wei Huang, Yu Zhou et al.

Tissue engineering is promising in realizing successful treatments of human body tissue loss that current methods cannot treat well or achieve satisfactory clinical outcomes. In scaffold-based bone tissue engineering, a high performance scaffold underpins the success of a bone tissue engineering strategy and a major direction in the field is to produce bone tissue engineering scaffolds with desirable shape, structural, physical, chemical and biological features for enhanced biological performance and for regenerating complex bone tissues. Three-dimensional (3D) printing can produce customized scaffolds that are highly desirable for bone tissue engineering. The enormous interest in 3D printing and 3D printed objects by the science, engineering and medical communities has led to various developments of the 3D printing technology and wide investigations of 3D printed products in many industries, including biomedical engineering, over the past decade. It is now possible to create novel bone tissue engineering scaffolds with customized shape, architecture, favorable macro-micro structure, wettability, mechanical strength and cellular responses. This article provides a concise review of recent advances in the R & D of 3D printing of bone tissue engineering scaffolds. It also presents our philosophy and research in the designing and fabrication of bone tissue engineering scaffolds through 3D printing.

Y. Çengel, M. Boles

Furkan H. Isikgor, Shynggys Zhumagali, Luis V. T. Merino et al.

G. Bolla, B. Sarma, A. Nangia

The subject of crystal engineering started in the 1970s with the study of topochemical reactions in the solid state. A broad chemical definition of crystal engineering was published in 1989, and the supramolecular synthon concept was proposed in 1995 followed by heterosynthons and their potential applications for the design of pharmaceutical cocrystals in 2004. This review traces the development of supramolecular synthons as robust and recurring hydrogen bond patterns for the design and construction of supramolecular architectures, notably, pharmaceutical cocrystals beginning in the early 2000s to the present time. The ability of a cocrystal between an active pharmaceutical ingredient (API) and a pharmaceutically acceptable coformer to systematically tune the physicochemical properties of a drug (i.e., solubility, permeability, hydration, color, compaction, tableting, bioavailability) without changing its molecular structure is the hallmark of the pharmaceutical cocrystals platform, as a bridge between drug discovery and pharmaceutical development. With the design of cocrystals via heterosynthons and prototype case studies to improve drug solubility in place (2000-2015), the period between 2015 to the present time has witnessed the launch of several salt-cocrystal drugs with improved efficacy and high bioavailability. This review on the design, synthesis, and applications of pharmaceutical cocrystals to afford improved drug products and drug substances will interest researchers in crystal engineering, supramolecular chemistry, medicinal chemistry, process development, and pharmaceutical and materials sciences. The scale-up of drug cocrystals and salts using continuous manufacturing technologies provides high-value pharmaceuticals with economic and environmental benefits.

A. A. Qabany, K. Soga

G. Towler, R. Sinnott

Qiguang Liu, Yanyun Li, Zhenghao Wu et al.

ABSTRACT In the era of artificial intelligence (AI)‐driven high‐performance computing, phase change materials (PCMs) are critical for high‐flux thermal management. PCMs are evolving toward high enthalpy, low interfacial thermal resistance (ITR), and high reliability. Herein, we design double‐brush phase‐change polymer (PVBS‐TMCn) crosslinked by B─O─B and Si─O─B dynamic bonds, characterized by the ultra‐fast relaxation time of 0.8 s under 80°C and closed‐loop cycling. This architecture enhances the content of phase‐change units for elevated theoretical enthalpy, while inherent multiple dynamic bonds and ultra‐low entanglement minimize enthalpy loss, resulting in a record enthalpy of 240.7 J·g−1. Furthermore, a composite of flexibility PVBS‐TMC14/24 and graphene foam films (PVBS‐TMC/GF) is fabricated as thermal interface materials using a stacking‐cutting strategy, which self‐adaptively modulates low‐ITR in response to temperature, owing to phase transition properties, ultra‐low modulus, and adaptive filling capability of dynamic polymer matrix. PVBS‐TMC/GF significantly generates better thermal management efficiency compared to commercial products. The topology design of double‐brush polymer dynamic networks and interfacial contact mechanisms provide fundamental insights for developing phase‐change adaptive materials and advancing thermal management.

Ha Eun Kang, Seong-Do Kim, Young Soo Yoon et al.

Nickel-rich layered oxide cathodes, typified by compositions such as LiNi₁₋ₓ₋ᵧCoₓMnᵧO₂ (NCM) have garnered significant attention as high-energy-density candidates for next-generation lithium-ion batteries. However, their widespread deployment is hindered by a confluence of structural degradation, surface instability, and poor interfacial compatibility under high voltage cycling. To address these multifaceted limitations, this review comprehensively examines recent advances in surface coating and bulk doping strategies, which have emerged as pivotal approaches for enhancing the electrochemical stability and longevity of Ni-rich cathodes. Surface coatings including oxides, phosphates, and fluorides have been shown to effectively mitigate electrolyte-induced parasitic reactions and reinforce cathode–electrolyte interfaces. Simultaneously, elemental doping at transition-metal, lithium, and oxygen sites offer promising pathways to suppress cation disorder, stabilize layered frameworks, and facilitate Li⁺ transport. Emphasis is placed on site-specific doping mechanisms, the role of multi-site (co-)doping, and their synergistic interplay with surface modification layers. By synthesizing recent findings, this review delineates how the judicious integration of coating and doping techniques can enable the rational design of Ni-rich cathodes with enhanced structural integrity, rate capability, and cycle life.

Yuandong Chen, Zhen Jiang

Operation mode is widely used in a refinery production process, bringing great convenience to its daily operations. However, the refinery scheduling model with operation mode makes the scheduling model become large and thus difficult to solve. In this article, we present a new refinery scheduling model based on Variable Driven Modelling (VDM) approach. The proposed model is with less variables, less constraints, and less branching nodes compared with the existing works. Furthermore, VDM builds model from a novel aspect of variable (i.e. variable-based), while the traditional method building model from rule aspect (i.e. rule-based). The model built by VDM has a more stable form and better readability, and is beneficial for building a widely applicable and standard refinery scheduling model. The results of numerical experiments show computational advantages of the proposed model.

Ying Dou, Junling Guo, Junke Shao et al.

Abstract Over the past decade, the most fundamental challenges faced by the development of lithium–sulfur batteries (LSBs) and their effective solutions have been extensively studied. To further transfer LSBs from the research phase into the industrial phase, strategies to improve the performance of LSBs under practical conditions are comprehensively investigated. These strategies can simultaneously optimize the sulfur cathode and Li‐metal anode to account for their interactions under practical conditions, without involving complex preparation or costly processes. Therefore, “two‐in‐one” strategies, which meet the above requirements because they can simultaneously improve the performance of both electrodes, are widely investigated. However, their development faces several challenges, such as confused design ideas for bi‐functional sites and simplex evaluation methods (i. e. evaluating strategies based on their bi‐functionality only). To date, as few reviews have focused on these challenges, the modification direction of these strategies is indistinct, hindering further developments in the field. In this review, the advances achieved in “two‐in‐one” strategies and categorizing them based on their design ideas are summarized. These strategies are then comprehensively evaluated in terms of bi‐functionality, large‐scale preparation, impact on energy density, and economy. Finally, the challenges still faced by these strategies and some research prospects are discussed.

Sampath Bharadwaj Kota, Seik Mansoor Ali, Sreenivas Jayanti

During the 2011 nuclear catastrophe at Fukushima Daiichi, Unit 3 had a sharper increase in containment pressure than Unit 2, with thermal stratification of the suppression pool cited as one of the contributing factors. In the present work, the buoyancy-induced circulation consequent to steam condensation in a large, toroidal pool of water is studied using computational fluid dynamics (CFD) simulations with a view to understanding the role of important design parameters of the suppression pool system. The tunnelling phenomenon observed in the development of the thermal stratification process is delineated in terms of the establishment of a thermocline. The effects of the number of steam injection points and the cross-section of the pool on thermal stratification characteristics have been investigated through a number of case studies. In all the cases, the surface temperature, which is responsible for over-pressurization of the containment, is found to be significantly higher than the bulk pool temperature. Multiple injection points with the same overall steam flow rate are found to lead to higher surface temperatures due to a shortened circulation path. For the same volume of pool water, the simulations show that a deeper and narrower pool gives rise to significantly higher temperatures than a wider and shallower pool. This is attributed to the relatively deeper penetration of the buoyancy-induced circulation into the pool.

Fengbao Liu, Jinsheng Sun, Xiao Luo

Drilling fluid systems for deep and ultra-deep wells are hampered by both high-temperature downhole environments and lengthy cycle periods. Suppose that the gel particle-plugging agent, the primary treatment agent in the system, fails to offer durable and stable plugging performance. In such a scenario, the borehole wall is susceptible to instability and landslide after prolonged immersion, leading to downhole accidents. In this study, novel core-shell gel particles (modified ZIF) with ZIF particles employed as the core material and organosilicon-modified polyethylene polyamine (PEPA) as the polymer shell were fabricated using PEPA, in-house synthesized (3-aminopropyl) triethoxysilane (APTS), and the ZIF-8 metal-organic framework (MOF) as the raw materials to enhance the long-term plugging performance of gel plugging agents. The modified ZIF particles are nanoscale polygonal crystals and differ from conventional core-shell gel particles in that they feature high molecular sieve catalytic activity due to the presence of numerous interior micropores and mesopores. As a result, modified ZIF exhibits the performance characteristics of both rigid and flexible plugging agents and has an excellent catalytic cross-linking effect on the sulfonated phenolic resin (SMP-3) and sulfonated lignite resin (SPNH) in drilling fluids. Consequently, a cross-linking reaction occurs when SMP-3 and SPNH flow through the spacings in the plugging layer formed by the modified ZIF particles. This increases the viscosity of the liquid phase and simultaneously generates an insoluble gel, forming a particle-gel composite plugging structure with the modified ZIF and significantly enhancing the long-term plugging performance of the drilling fluid.

Germán Pérez-Sánchez, Nicolas Schaeffer, Tamar L. Greaves et al.

Solutions of surfactants exhibit remarkable features, such as a tunable amphiphilic character, which can further be varied for ionic surfactants through variations in their Coulombic interactions. These properties are very useful in many industrial applications such as in extraction, purification, and formulation processes, as detergents, wetting agents, or emulsifiers. Rather unexpectedly, the addition of tetrabutylammonium chloride ([N4,4,4,4]Cl) to solutions of the ionic surfactant of sodium dodecyl sulphate (SDS) results in the appearance of a phase transition above the lower critical solution temperature (LCST), a property usually associated with non-ionic surfactants. The aim of this study is to provide a detailed nanoscopic scenario on the interaction between SDS micelles and [N4,4,4,4]Cl moieties to better understand the nature of the LCST cloud point and how to confer it to a given ionic surfactant system. A coarse-grained molecular dynamics (CG-MD) computational framework, under the latest MARTINI 3.0 force field, was developed and validated using available literature data. The impact of [N4,4,4,4]Cl concentration in the phase of SDS micellar aqueous solutions was then characterized and compared using experimental results. Specifically, dynamic light scattering (DLS) measurements and small-angle X-ray scattering (SAXS) profiles were obtained at different [N4,4,4,4]+/[DS]- molar ratios (from 0.0 to 1.0) and compared with the CG-MD results. A good agreement between computer simulations and experimental findings was obtained, reinforcing the suitability of GC-MD to simulate complex phase behaviors. When the [N4,4,4,4]+/[DS]- molar ratio is < 0.5, a weak impact of the cation in the micellar distribution was found whereas for ratios > 0.5, the system yielded clusters of enclosed small [DS]- aggregates. Thus, the CG-MD simulations showed the formation of mixed [DS]- and [N4,4,4,4]+ aggregates with [N4,4,4,4]+ cations acting as a bridge between small [DS]- micelles. The CG-MD simulation framework developed in this work captured the role of [N4,4,4,4]+ in the micellar phase transition whilst improving the results obtained with preceding computer models for which the limitations on capturing SDS and [N4,4,4,4]Cl mixtures in aqueous solutions are also shown in detail.

Tian Jingyi, Cortecchia Daniele, Wang Yutao et al.

Halide perovskite metasurfaces are attracting increasing interest for applications in light-emitting and display technologies. To access the wide range of colors required for these applications, the main mechanism exploited thus far has been chemical engineering of the perovskite compounds – this constitutes a significant limitation for the dynamic switching of optical response desirable in actual devices. Here we demonstrate polarization-dependent, dynamic control of structural color and emission wavelength in an all-dielectric phase-change halide perovskite nanograting metasurface, by temperature tuning. This is underpinned by the significant change in the perovskite optical constants which accompanies its phase-transition around room temperature. The functionalities demonstrated in our work bearing potential for applications in light-emitting devices, displays and spatial-light-modulators.

Edward Bormashenko, Irina Legchenkova, Mark Frenkel et al.

In this paper, informational (Shannon) measures of symmetry are introduced and analyzed for patterns built of 1D and 2D shapes. The informational measure of symmetry <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>H</mi><mrow><mi>s</mi><mi>y</mi><mi>m</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></semantics></math></inline-formula> characterizes the averaged uncertainty in the presence of symmetry elements from group <i>G</i> in a given pattern, whereas the Shannon-like measure of symmetry <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi mathvariant="sans-serif">Ω</mi><mrow><mi>s</mi><mi>y</mi><mi>m</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></semantics></math></inline-formula> quantifies the averaged uncertainty of the appearance of shapes possessing a total of <i>n</i> elements of symmetry belonging to group <i>G</i> in a given pattern. <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>H</mi><mrow><mi>s</mi><mi>y</mi><mi>m</mi></mrow></msub><mrow><mo>(</mo><mrow><msub><mi>G</mi><mn>1</mn></msub></mrow><mo>)</mo></mrow><mo>=</mo><msub><mi mathvariant="sans-serif">Ω</mi><mrow><mi>s</mi><mi>y</mi><mi>m</mi></mrow></msub><mrow><mo>(</mo><mrow><msub><mi>G</mi><mn>1</mn></msub></mrow><mo>)</mo></mrow><mo>=</mo><mn>0</mn></mrow></semantics></math></inline-formula> for the patterns built of irregular, non-symmetric shapes, where <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>G</mi><mn>1</mn></msub></mrow></semantics></math></inline-formula> is the identity element of the symmetry group. Both informational measures of symmetry are intensive parameters of the pattern and do not depend on the number of shapes, their size, and the entire area of the pattern. They are also insensitive to the long-range order (translational symmetry) inherent for the pattern. Additionally, informational measures of symmetry of fractal patterns are addressed, the mixed patterns including curves and shapes are considered, the time evolution of Shannon measures of symmetry are examined, the close-packed and dispersed 2D patterns are analyzed, and an application of the suggested measures of symmetry for the analysis of the chemical reaction is demonstrated.

M. Tagliabue, D. Farrusseng, S. Valencia et al.

Arash Fattah-alhosseini, Maryam Molaei, Meisam Nouri et al.

The plasma electrolytic oxidation (PEO) surface modification process is able to improve the surface characteristics of titanium and titanium alloys by forming TiO2 coatings. Implementing the PEO process enhances corrosion and wear protection, tunes optical properties, and more importantly, modifies the biological activities of titanium and also its alloys. The surface features can be further enhanced by adding proper additives in the form of particles, sheets, powders, or compounds into electrolytes, forming TiO2 composite coatings with modified properties compared to the basic TiO2 coatings. With a wide range of desirable physical, mechanical, chemical, thermal, electrical, optical, and biological characteristics, graphene (G) and G-derivatives (i.e., graphene oxide (GO) and reduced graphene oxide (rGO)) are among the top additive choices used in PEO composite coatings production. The porous nature of PEO coatings provides a suitable place for the accumulation of G and GO that can change the features of the surface significantly. This article reviews the results of studies on the properties of PEO coatings modified by G, GO, and rGO formed on titanium and also its alloys. The addition of G and G-derivatives influences the growth process, microstructure, surface morphology, and phase composition of the formed coatings. Particularly, the hardness of the coatings is increased, corrosion and wear resistance are enhanced, optical properties and optoelectronic behavior are tuned, and last but not least bioactivity and biocompatibility of the coatings are modified after the addition of G and G-derivatives.