Hasil untuk "Chemical engineering"

Chunping Xu, Prasaanth Ravi Anusuyadevi, C. Aymonier et al.

Photocatalysis is a green technology which converts abundantly available photonic energy into useful chemical energy. With a rapid rise of flow photoreactors in the last decade, the design and development of novel semiconductor photocatalysts is happening at a blistering rate. Currently, developed synthetic approaches have allowed the design of diverse modified/unmodified semiconductor materials exhibiting enhanced performances in heterogeneous photocatalysis. In this review, we have classified the so far reported highly efficient modified/unmodified semiconductor photocatalysts into four different categories based on the elemental composition, band gap engineering and charge carrier migration mechanism in composite photocatalysts. The recent synthetic developments are reported for each novel semiconductor photocatalyst within the four different categories, namely: pure semiconductors, solid solutions, type-II heterojunction nanocomposites and Z-scheme. The motivation behind the synthetic upgrading of modified/unmodified (pure) semiconductor photocatalysts along with their particular photochemical applications and photoreactor systems have been thoroughly reviewed.

K. Savjani, A. Gajjar, J. Savjani

Solubility, the phenomenon of dissolution of solute in solvent to give a homogenous system, is one of the important parameters to achieve desired concentration of drug in systemic circulation for desired (anticipated) pharmacological response. Low aqueous solubility is the major problem encountered with formulation development of new chemical entities as well as for the generic development. More than 40% NCEs (new chemical entities) developed in pharmaceutical industry are practically insoluble in water. Solubility is a major challenge for formulation scientist. Any drug to be absorbed must be present in the form of solution at the site of absorption. Various techniques are used for the enhancement of the solubility of poorly soluble drugs which include physical and chemical modifications of drug and other methods like particle size reduction, crystal engineering, salt formation, solid dispersion, use of surfactant, complexation, and so forth. Selection of solubility improving method depends on drug property, site of absorption, and required dosage form characteristics.

A. Luntz, B. McCloskey

Shunzhi Wang, C. McGuirk, Andrea I. d’Aquino et al.

Due to their well‐defined 3D architectures, permanent porosity, and diverse chemical functionalities, metal–organic framework nanoparticles (MOF NPs) are an emerging class of modular nanomaterials. Herein, recent developments in the synthesis and postsynthetic surface functionalization of MOF NPs that strengthen the fundamental understanding of how such structures form and grow are highlighted; the internal structure and external surface properties of these novel nanomaterials are highlighted as well. These fundamental advances have resulted in MOF NPs being used as components in chemical sensors, biological probes, and membrane separation materials, as well as building blocks for colloidal crystal engineering.

Meiling Liu, Zipeng Zhao, X. Duan et al.

Proton‐exchange‐membrane fuel cells (PEMFCs) are of considerable interest for direct chemical‐to‐electrical energy conversion and may represent an ultimate solution for mobile power supply. However, PEMFCs today are primarily limited by the sluggish kinetics of the cathodic oxygen reduction reaction (ORR), which requires a significant amount of Pt‐based catalyst with a substantial contribution to the overall cost. Hence, promoting the activity and stability of the needed catalyst and minimizing the amount of Pt loaded are central to reducing the cost of PEMFCs for commercial deployment. Considerable efforts have been devoted to improving the catalytic performance of Pt‐based ORR catalysts, including the development of various Pt nanostructures with tunable sizes and chemical compositions, controlled shapes with selectively displayed crystallographic surfaces, tailored surface strains, surface doping, geometry engineering, and interface engineering. Herein, a brief introduction of some fundamentals of fuel cells and ORR catalysts with performance metrics is provided, followed by a detailed description of a series of strategies for pushing the limit of high‐performance Pt‐based catalysts. A brief perspective and new insights on the remaining challenges and future directions of Pt‐based ORR catalysts for fuel cells are also presented.

Ruby Dwivedi, Sumit Kumar, Rahul Pandey et al.

Bone tissue engineering using polymer based scaffolds have been studied a lot in last decades. Considering the qualities of all the polymers desired to be used as scaffolds, Polycaprolactone (PCL) polyester apart from being biocompatible and biodegradable qualifies to an appreciable level due its easy availability, cost efficacy and suitability for modification. Its adjustable physio-chemical state, biological properties and mechanical strength renders it to withstand physical, chemical and mechanical, insults without significant loss of its properties. This review aims to critically analyse the efficacy of PCL as a biomaterial for bone scaffolds.

J. Fried

Y. Fung, S. Cowin

Fuzhong Zhang, J. Carothers, J. Keasling

V. Cardoso, A. Francesko, C. Ribeiro et al.

A. Rosales, K. Anseth

Tehseen Riaz, Rabia Zeeshan, F. Zarif et al.

B. Laycock, M. Nikolic, John M. Colwell et al.

The determination of the safe working life of polymer materials is important for their successful use in engineering, medicine and consumer-goods applications. An understanding of the physical and chemical changes to the structure of widely-used polymers such as the polyolefins, when exposed to aggressive environments, has provided a framework for controlling their ultimate service lifetime by either stabilising the polymer or chemically accelerating the degradation reactions. The recent focus on biodegradable polymers as replacements for more bio-inert materials such as the polyolefins in areas as diverse as packaging and as scaffolds for tissue engineering has highlighted the need for a review of the approaches to being able to predict the lifetime of these materials. In many studies the focus has not been on the embrittlement and fracture of the material (as it would be for a polyolefin) but rather the products of degradation, their toxicity and ultimate fate when in the environment, which may be the human body. These differences are primarily due to time-scale. Different approaches to the problem have arisen in biomedicine, such as the kinetic control of drug delivery by the bio-erosion of polymers, but the similarities in mechanism provide real prospects for the prediction of the safe service lifetime of a biodegradable polymer as a structural material. Common mechanistic themes that emerge include the diffusion-controlled process of water sorption and conditions for surface versus bulk degradation, the role of hydrolysis versus oxidative degradation in controlling the rate of polymer chain scission and strength loss and the specificity of enzyme-mediated reactions.

Juan Zhou, Yong Yang, Chun-Yang Zhang

Fei Pei, Taihua An, Jun Zang et al.

Suqing Wang, Lu Xia, Le Yu et al.

G. Wang, Tristan Konolige, Christo Wilson et al.

Northeastern University's approach to undergraduate education in biomedical engineering is oriented toward complementing our students' strong back ground in both theory and practice in the traditional disciplines of electrical and computer (ECE), mechanical and industrial, and chemical engineering. Our undergraduate program operates around four key elements. Exposure to life science courses such as biology, psychology, and chemistry provides an appropriate foundation for real-world application of biomedical engineering.

C. N. Sawyer, P. McCarty, G. Parkin

F. Selimefendigil, M. Khoshvaght-Aliabadi

J. Lannutti, D. Reneker, T. Ma et al.