Astrid Ahlinder  Tiziana Fuoco  Álvaro Morales-López  Mohammed A. Yassin  Kamal Mustafa  Anna Finne-Wistrand 《应用聚合物科学杂志》2020,137(15):48550

Although additive manufacturing through melt extrusion has become increasingly popular as a route to design scaffolds with complex geometries the technique if often limited by the reduction in molecular weight and the viscoelastic response when degradable aliphatic polyesters of high molecular weight are used. Here we use a melt extruder and fused filament fabrication printer to produce a reliable nondegradative route for scaffold fabrication of medical grade copolymers of L-lactide, poly(ε-caprolactone-co-L-lactide), and poly(L-lactide-co-trimethylene carbonate). We show that degradation is avoided using filament extrusion and fused filament fabrication if the process parameters are deliberately chosen based upon the rheological behavior, mechanical properties, and polymer composition. Structural, mechanical, and thermal properties were assessed throughout the process to obtain comprehension of the relationship between the rheological properties and the behavior of the medical grade copolymers in the extruder and printer. Scaffolds with a controlled architecture were achieved using high-molecular-weight polyesters exhibiting a large range in the elastic response causing negligible degradation of the polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48550.  相似文献   

    

Hadi Roohani Ghehsareh  Maryam Sadat Seidzadeh  Seyed Kamal Etesami 《International Journal of Numerical Modelling》2020,33(6):e2756

Pseudospectral techniques are known as powerful tools and highly accurate solvers to deal with partial differential equations. In the current work, a local meshless technique in Pseudospectral mode is employed to deal with an interesting and general mathematical model which describes anomalous electrodiffusion of ions in spiny dendrites, the two-dimensional variable-order time fractional nonlinear cable equation. For this purpose, at first step a second-order implicit difference method and a modified second-order weighted and shifted Grünwald difference scheme are used to discretize the appearing integer and variable order fractional time derivatives, respectively. Then a local Pseudospectral meshless method based on the sufficiently smooth compactly supported radial point interpolation basis functions is formulated for solving the semidiscretized problem. The main advantage of the proposed computational technique is that it leads to a sparse and better-conditioned system of algebraic equations. Finally, some numerical experiments are presented to demonstrate and verify the performance and accuracy of the method.  相似文献   

    

Di Xing  Cheng-Chieh Lin  Phillip Won  Rong Xiang  Tzu-Pei Chen  A. Syazwan A. Kamal  Yang-Chun Lee  Ya-Lun Ho  Shigeo Maruyama  Seung Hwan Ko  Chun-Wei Chen  Jean-Jacques Delaunay 《Advanced functional materials》2021,31(28):2102375

Plasmonic nanolasers provide a valuable opportunity for expanding sub-wavelength applications. Due to the potential of on-chip integration, semiconductor nanowire (NW)-based plasmonic nanolasers that support the waveguide mode attract a high level of interest. To date, perovskite quantum dots (QDs) based plasmonic lasers, especially nanolasers that support plasmonic-waveguide mode, are still a challenge and remain unexplored. Here, metallic NW coupled CsPbBr₃ QDs plasmonic-waveguide lasers are reported. By embedding Ag NWs in QDs film, an evolution from amplified spontaneous emission with a full width at half maximum (FWHM) of 6.6 nm to localized surface plasmon resonance (LSPR) supported random lasing is observed. When the pump light is focused on a single Ag NW, a QD-NW coupled plasmonic-waveguide laser with a much narrower emission peak (FWHM = 0.4 nm) is realized on a single Ag NW with the uniform polyvinylpyrrolidone layer. The QDs serve as the gain medium while the Ag NW serves as a resonant cavity and propagating plasmonic lasing modes. Furthermore, by pumping two Ag NWs with different directions, a dual-wavelength lasing switch is realized. The demonstration of metallic NW coupled QDs plasmonic nanolaser would provide an alternative approach for ultrasmall light sources as well as fundamental studies of light matter interactions.  相似文献   

    

Amit Kumar  Vishal S. Chauhan  Rajeev Kumar  Kamal Prasad 《Integrated ferroelectrics》2018,192(1):67-79

Electromagnetic responses of cement–PZT composites under impact loading have been presented in this work. The values of density, dielectric constant and EMR voltage increase while that of porosity and loss tangent decrease with increase in PZT content. Filler (PZT) concentration dependent dielectric constant as well as loss tangent data shows exponential variation. The emitted EMR voltage as well as average EMR energy release rate for 21?cm height of impact increase from 1.03 V to 2.24 V and 0.10092 V²-sec/sec to 0.4635 V²-sec/sec respectively with the increasing PZT content (5% to 40%). The EMR responses of the composites were also found to be proportional to the height of impact in all the composites tested, indicating that the measurement of EMR responses from the cement based composites may be useful for deformation monitoring.  相似文献   

    

Ahmed Hossam‐Eldin  Kamal Abed  Karim Youssef  Hossam Kotb 《IEEJ Transactions on Electrical and Electronic Engineering》2019,14(9):1409-1415

In this article, the specific energy consumption (SEC) and water production cost (C_w) of a reverse osmosis (RO) desalination plant are investigated experimentally under different working conditions. The plant is fed by a hybrid renewable energy source. The frequency of the high‐pressure pump motor is changed from 35 to 50 Hz using a variable frequency drive. In addition, the feed water temperature and the reject control valve are controlled. This article investigates the effects of SEC, C_w, permeate salt concentration, and plant productivity. The results show that both SEC and C_w are reduced by increasing the frequency up to 45 Hz before rising thereafter. Also, SEC and C_w decrease with increasing feed temperature and reduced reject valve opening. As a result, the optimum values of SEC and C_w are found at 45 Hz and 40 °C with 25% valve opening, representing 4.5  kWh/m³ and 0.55 $/m³, respectively. Then, a model is proposed for the RO plant using the Matlab identification toolbox. The model is validated by comparing the simulation results with the experimental data. Based on the best fit ratio, the model presents good results for verification, which can be used for a process control design. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.  相似文献   

    

Kamal Kumar  Herbert Waldmann 《Israel journal of chemistry》2019,59(1-2):41-51

Chemical biology and drug discovery are instrumental sciences to address unmet medical needs and to gain a deeper understanding of normal and disease state biology in mammalian systems. Unlike most genetic tools, the small molecule modulation of biology is reversible, controllable in space, time and quantity, avoids the removal of gene products from cellular systems and thus enables perturbation of biology in its native state. Natural products, their derivatives as well as small molecules based on the core‐scaffolds of natural products including natural product fragments allow targeting unique, biologically relevant fractions of chemical space that may deliver quality tool compounds. In this essay, we discuss various synthesis approaches inspired by natural products to deliver biologically active small molecules. We argue and provide evidence that inspiration by natural product structure remains a powerful guiding principle for the development of novel approaches to the study biology by means of novel bioactive small molecules.  相似文献   

    

Noresah Said  Hasrinah Hasbullah  Muhammad Nidzhom Zainol Abidin  Ahmad Fauzi Ismail  Pei Sean Goh  Mohd Hafiz Dzarfan Othman  Siti Hamimah Sheikh Abdul Kadir  Fatmawati Kamal  Mohd Sohaimi Abdullah  Be Cheer Ng 《应用聚合物科学杂志》2019,136(21):47502

Protein existence in wastewater is an important issue in wastewater management because proteins are generally present as contaminants and foulants. Hence, in this study, we focused on designing a polysulfone (PSf) hollow-fiber membrane embedded with hydrophilic iron oxide nanoparticles (IONPs) for protein purification by means of ultrafiltration. Before membrane fabrication, the dispersion stability of the IONPs was enhanced by the addition of a stabilizer, namely, citric acid (CA). Next, PSf–IONP–CA nanocomposite hollow-fiber membranes were prepared via a dry–wet spinning process and then characterized in terms of their hydrophilicity and morphology. Ultrafiltration and adsorption experiments were then conducted with bovine serum albumin as a model protein. The results that an IONP/CA weight ratio of 1:20 contributed to the most stable IONP dispersion. It was also revealed that the membrane incorporated with IONP–CA at a weight ratio of 1:20 exhibited the highest pure water permeability (58.6 L m⁻² h⁻¹ bar⁻¹) and protein rejection (98.5%) while maintaining a low protein adsorption (3.3 μg/cm²). The addition of well-dispersed IONPs enhanced the separation features of the PSf hollow-fiber membrane for protein purification. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47502.  相似文献   

    

Narges Kiomarsipour  Mohsen Ghasemi  Kamal Ghani 《Color research and application》2019,44(6):917-924

Using black coatings and materials with high light absorbance that are capable of absorbing photons at visible and longer wavelengths is a very effective way to reduce unwanted stray light, also known as optical noise, within optical equipment. These lights can be greatly reduced to a reasonable level by functional and performable black coatings that are modified to absorb incident light as much as possible by their specific pigments. In the present work, several carbonaceous pigments were synthesized for the first time from wasteful materials and their optical properties in the visible and near‐infrared ranges studied. First, MCM‐48 and SBA‐15 were synthesized at different conditions and were then used as templates for carbonaceous products. SSS‐1 (the carbonic pigment synthesized by the mixture of sucrose and sodium silicate), SSS‐2 (the carbonic pigment synthesized by the mixture of sawdust and sodium silicate), and mesoporous carbon pigments (CMK‐3 and CMK‐1 with different levels of saturations) were synthesized. Finally, their structure, morphology, and optical properties were investigated by X‐ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE‐SEM), and Diffuse Reflectance Spectroscopy (DRS). The results indicated that the SSS‐1 pigment had a lower reflectance (below 1%) than carbon black (about 2.5%) in the visible region despite it being more cost‐effective than carbon black. The mesoporous pigments showed very high light absorbance in the visible region (about 2.5%). Compared with other black pigments, the CMK‐1 was the blackest synthesized material with a very low reflectance (about 0.05% in visible region), making it an ideal candidate as a super black pigment for reducing unwanted stray light within optical equipment.  相似文献   

    

Sajad Razavi Bazaz  Navid Kashaninejad  Shohreh Azadi  Kamal Patel  Mohsen Asadnia  Dayong Jin  Majid Ebrahimi Warkiani 《Advanced Materials Technologies》2019,4(10)

Polydimethylsiloxane (PDMS) is a long‐standing material of significant interest in microfluidics due to its unique features. As such, rapid prototyping of PDMS‐based microchannels is of great interest. The most prevalent and conventional method for fabrication of PDMS‐based microchips relies on softlithography, the main drawback of which is the preparation of a master mold, which is costly and time‐consuming. To prevent the attachment of PDMS to the master mold, silanization is necessary, which can be detrimental for cellular studies. Additionally, using coating the mold with a cell‐compatible surfactant adds extra preprocessing time. Recent advances in 3D printing have shown great promise in expediting microfabrication. Nevertheless, current 3D printing techniques are sub‐optimal for PDMS softlithography. The feasibility of producing master molds suitable for rapid softlithography is demonstrated using a newly developed 3D‐printing resin. Moreover, the utility of this technique is showcased for a number of widely used applications, such as concentration gradient generation, particle separation, cell culture (to show biocompatibility of the process), and fluid mixing. This can open new opportunities for biologists and scientists with minimum knowledge of microfabrication to build functional microfluidic devices for their basic and applied research.  相似文献   

    

Kang Yang  Hongye He  Kamal Al‐Sabahi  Zuping Zhang 《Concurrency and Computation》2019,31(17)

We present EcForest, an extractive summarization model through Enhanced Sentence Embedding and Cascade Forest. Sentence representation is of great significance for many summarization methods. Bag‐of‐words mostly fails to grasp the semantics, and typical embedding models cannot capture more complex semantic features, such as polysemy and the meaning of a phrase, which is usually ignored by simply averaging the word embeddings included in a sentence. To this end, we propose Enhanced Sentence Embedding (ESE) model to solve such drawbacks via mapping several valid features to dense vectors. Essentially, the enhanced sentence embedding is a novel model for improving the distributed representation of sentence. Our sentence embedding model is universally applicable and it can be adapted to other NLP tasks. Moreover, deep forest is used as a sentence extraction algorithm for its robustness to the hyper‐parameters and its efficient training algorithm compared to deep neural network. The evaluation of variant models proposed in this work proves the validation of the enhanced sentence embedding. The comparison results between EcForest and several baselines on two different datasets demonstrate that the proposed summarization model performs better than or with high competitiveness to the state‐of‐the‐art.  相似文献