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Mechanical engineering

Anna Vilajeliu-Pons, Christin Koch, Maria D Balaguer, Jesús Colprim, Falk Harnisch, Sebastià Puig
Removal of nitrogen, mainly in form of ammonium (NH4+), in wastewater treatment plants (WWTPs) is a highly energy demanding process, mainly due to aeration. It causes costs of about half a million Euros per year in an average European WWTP. Alternative, more economical technologies for the removal of nitrogen compounds from wastewater are required. This study proves the complete anoxic conversion of ammonium (NH4+) to dinitrogen gas (N2) in continuously operated bioelectrochemical systems at the litre-scale...
December 1, 2017: Water Research
Cesar de la Fuente-Nunez, Beatriz Torres Meneguetti, Octávio Luiz Franco, Timothy K Lu
We review here recent discoveries in the exciting new field of neuromicrobiology. This field encompasses the interactions between the microbiome and the central nervous system. The microbiome has a tremendous impact on human health. In particular, the gut microbiota may play a key role in many essential processes in health and disease via the activity of the gut-brain axis, possibly contributing to autism spectrum disorders, Alzheimer's disease, Parkinson's disease, depression, and anxiety disorder. Gut microbes may also be involved in nociception, complex host behaviors, and brain development...
December 8, 2017: ACS Chemical Neuroscience
Christopher M Madl, Sarah C Heilshorn
Stem cells are a powerful resource for many applications including regenerative medicine, patient-specific disease modeling, and toxicology screening. However, eliciting the desired behavior from stem cells, such as expansion in a naïve state or differentiation into a particular mature lineage, remains challenging. Drawing inspiration from the native stem cell niche, hydrogel platforms have been developed to regulate stem cell fate by controlling microenvironmental parameters including matrix mechanics, degradability, cell-adhesive ligand presentation, local microstructure, and cell-cell interactions...
December 8, 2017: Annual Review of Biomedical Engineering
Henry Y H Tang, John A Tainer, Greg L Hura
Measuring distances within or between macromolecules is necessary to understand the chemistry that biological systems uniquely enable. In performing their chemistry, biological macromolecules undergo structural changes over distances ranging from atomic to micrometer scales. X-ray and neutron scattering provide three key assets for tackling this challenge. First, they may be conducted on solutions where the macromolecules are free to sample the conformations that enable their chemistry. Second, there are few limitations on chemical environment for experiments...
2017: Advances in Experimental Medicine and Biology
Yuan Wan, Lixue Wang, Chuandong Zhu, Qin Zheng, Guoxiang Wang, Jinlong Tong, Yuan Fang, Yiqiu Xia, Gong Cheng, Xia He, Si-Yang Zheng
Extracellular nanovesicles (ENV) released by many cells contain lipids, proteins and nucleic acids that contribute to intercellular communication. ENV have emerged as biomarkers and therapeutic targets but they have also been explored as drug delivery vehicles. However, for the latter application clinical translation has been limited by low yield and inadequate targeting effects. ENV vectors with desired targeting properties can be produced from parental cells engineered to express membrane-bound targeting ligands, or they can be generated by fusion with targeting liposomes, however, neither approach has met clinical requirements...
December 7, 2017: Cancer Research
Li Wang, Siping Wei, Xianchao Pan, Pingxian Liu, Xi Du, Chun Zhang, Lin Pu, Qin Wang
A randomized library is constructed based on pET30a-CYP119-T214V plasmid. This library of random mutants of P450 119 T214V was screened by the reduced CO-difference spectra and the epoxidation of styrene. By using the directed evolution, a new P450119 quadruple mutant S148P/I161T/K199E/T214V is constructed, expressed and purified. This quadruple mutant is found to significantly increase the turnover rate and conversion for the asymmetric epoxidation of styrene and its derivatives. The kcat value of cis-beta-methylstyrene epoxidation catalysed by the quadruple mutant exhibits approximately 10-fold increase relative to the previously reported T213M mutant under the same conditions...
December 7, 2017: Chemistry: a European Journal
Akalabya Bissoyi, Abhishek Kumar Singh, Subrat Kumar Pattanayak, Arindam Bit, Sudip Kumar Sinha, Ashish Patel, Vishal Jain, Pradeep Kumar Patra
The development of engineered bone tissue, as a promising alternative to conventional bone grafts, has so far not proven successful and still remains challenging. Thus, attempts have been made in the present study to synthesize polyelectrolyte complex (PEC) scaffolds by blending chitosan (CS) to silk fibroin (SF) derived from the non-mulberry silkworm (Antheraea pernyi) at three different pH values (5.0, 6.0, and 7.0), and to characterize them in terms of morphology, ultrastructure and mechanical properties with scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy, x-ray diffraction and tensile strength analyses...
December 7, 2017: Biomedical Materials
Jian Gao, Tzu-Ping Ko, Lu Chen, Satish R Malwal, Jianan Zhang, Xiangying Hu, Fiona Qu, Weidong Liu, Jian-Wen Huang, Ya-Shan Cheng, Chun-Chi Chen, Yunyun Yang, Yonghui Zhang, Eric Oldfield, Rey-Ting Guo
We report the first X-ray crystallographic structure of the "head-to-middle" prenyltransferase, isosesquilavandulyl diphosphate synthase, involved in biosynthesis of the merochlorin class of antibiotics. The protein adopts the ζ or cis-prenyl transferase fold but remarkably, unlike tuberculosinol adenosine synthase and other cis-prenyl transferases (e.g. cis-farnesyl, decaprenyl, undecaprenyl diphosphate synthases), the large, hydrophobic side-chain does not occupy a central hydrophobic tunnel. Instead, it occupies a surface pocket oriented at ~90º to the hydrophobic tunnel...
December 7, 2017: Angewandte Chemie
Xiaojian Wu, Mijin Kim, Hyejin Kwon, YuHuang Wang
Quantum defects are an emerging class of synthetic single photon emitters that hold potential for near-infrared imaging, chemical sensing, materials engineering, and quantum information processing. Herein, we show it is possible to optically direct the synthetic creation of molecularly tunable fluorescent quantum defects in semiconducting single-walled carbon nanotube hosts through photochemical reactions. By exciting the host semiconductor with light that resonates with its electronic transition, we find that halide-containing aryl groups can covalently bond to the sp2 carbon lattice...
December 7, 2017: Angewandte Chemie
Liujing Chen, Fulin Jiang, Yini Qiao, Hong Li, Zhangming Wei, Tu Huang, Jingxiang Lan, Yue Xia, Juan Li
Stem cell-based tissue engineering provides a prospective strategy to bone tissue repair. Bone tissue repair begins at the recruitment and directional movement of stem cells, and ultimately achieved on the directional differentiation of stem cells. The migration and differentiation of stem cells are regulated by nucleoskeletal stiffness. Mechanical properties of lamin A/C contribute to the nucleoskeletal stiffness and consequently to the regulation of cell migration and differentiation. Nuclear lamin A/C determines cell migration through the regulation of nucleoskeletal stiffness and rigidity and involve in nuclear-cytoskeletal coupling...
December 7, 2017: Journal of Cellular Physiology
N F D AlDala'een, W N K W Mohamad, N Alias, A M Ali, J Shaikh Mohammed
There is an increasing interest in bioinspired dynamic materials. Abundant illustrations of protein domains exist in nature, with remarkable ligand binding characteristics and structures that undergo conformational changes. For example, calmodulin (CaM) can have three conformational states, which are the unstructured Apo-state, Ca2+-bound ligand-exposed binding state, and compact ligand-bound state. CaM's mechanical response to biological cues is highly suitable for engineering dynamic materials. The distance between CaM globular terminals in the Ca2+-bound state is 5 nm and in the ligand-bound state is 1...
December 7, 2017: Soft Matter
Alessandro Tocchio, Naside Gozde Durmus, Kaushik Sridhar, Vigneshwaran Mani, Bukre Coskun, Rami El Assal, Utkan Demirci
In nature, cells self-assemble at the microscale into complex functional configurations. This mechanism is increasingly exploited to assemble biofidelic biological systems in vitro. However, precise coding of 3D multicellular living materials is challenging due to their architectural complexity and spatiotemporal heterogeneity. Therefore, there is an unmet need for an effective assembly method with deterministic control on the biomanufacturing of functional living systems, which can be used to model physiological and pathological behavior...
December 7, 2017: Advanced Materials
Javier García-Castro, Ilyas Singeç
Rare diseases are highly diverse and complex regarding molecular underpinning and clinical manifestation and afflict millions of patients worldwide. The lack of appropriate model systems with face and construct validity and the limited availability of live tissues and cells from patients has largely hampered the understanding of underlying disease mechanisms. As a consequence, there are no adequate treatment options available for the vast majority of rare diseases. Over the last decade, remarkable progress in pluripotent and adult stem cell biology and the advent of powerful genomic technologies opened up exciting new avenues for the investigation, diagnosis, and personalized therapy of intractable human diseases...
2017: Advances in Experimental Medicine and Biology
Kengo Kanetaka, Shinichiro Kobayashi, Susumu Eguchi
Advances in tissue engineering techniques have made it possible to use human cells as biological material. This has enabled pharmacological studies to be conducted to investigate drug effects and toxicity, to clarify the mechanisms underlying diseases, and to elucidate how they compensate for impaired organ function. Many researchers have tried to construct artificial organs using these techniques, but none has succeeded in growing a whole organ. Unlike other digestive organs with complicated functions, such as the processing and absorption of nutrients, the esophagus has the relatively simple function of transporting content, which can be replicated easily by a substitute...
December 6, 2017: Surgery Today
Yi-An Lin, Myungshim Kang, Wei-Chiang Chen, Yu-Chuan Ou, Andrew G Cheetham, Pei-Hsun Wu, Denis Wirtz, Sharon M Loverde, Honggang Cui
Supramolecular filament hydrogels are an emerging class of biomaterials that hold great promise for regenerative medicine, tissue engineering, and drug delivery. However, fine-tuning of their bulk mechanical properties at the molecular level without altering their network structures remains a significant challenge. Here we report an isomeric strategy to construct amphiphilic peptides through the conjugation of isomeric hydrocarbons to influence the local viscoelastic properties of their resulting supramolecular hydrogels...
December 7, 2017: Biomaterials Science
Vladimíra Moulisová, Sara Poveda-Reyes, Esther Sanmartín-Masiá, Luis Quintanilla-Sierra, Manuel Salmerón-Sánchez, Gloria Gallego Ferrer
Gelatin-hyaluronic acid (Gel-HA) hybrid hydrogels have been proposed as matrices for tissue engineering because of their ability to mimic the architecture of the extracellular matrix. Our aim was to explore whether tyramine conjugates of Gel and HA, producing injectable hydrogels, are able to induce a particular phenotype of encapsulated human mesenchymal stem cells without the need for growth factors. While pure Gel allowed good cell adhesion without remarkable differentiation and pure HA triggered chondrogenic differentiation without cell spreading, the hybrids, especially those rich in HA, promoted chondrogenic differentiation as well as cell proliferation and adhesion...
November 30, 2017: ACS Omega
Pengsong Li, Xiaofen Fu, Lei Zhang, Zhiyu Zhang, Jihong Li, Shizhong Li
Background: High temperature inhibits cell growth and ethanol fermentation of Saccharomyces cerevisiae. As a complex phenotype, thermotolerance usually involves synergistic actions of many genes, thereby being difficult to engineer. The overexpression of either endogenous or exogenous stress-related transcription factor genes in yeasts was found to be able to improve relevant stress tolerance of the hosts. Results: To increase ethanol yield of high-temperature fermentation, we constructed a series of strains of S...
2017: Biotechnology for Biofuels
Ayşenur Eminoğlu, Sean Jean-Loup Murphy, Marybeth Maloney, Anthony Lanahan, Richard J Giannone, Robert L Hettich, Shital A Tripathi, Ali Osman Beldüz, Lee R Lynd, Daniel G Olson
Background: With the discovery of interspecies hydrogen transfer in the late 1960s (Bryant et al. in Arch Microbiol 59:20-31, 1967), it was shown that reducing the partial pressure of hydrogen could cause mixed acid fermenting organisms to produce acetate at the expense of ethanol. Hydrogen and ethanol are both more reduced than glucose. Thus there is a tradeoff between production of these compounds imposed by electron balancing requirements; however, the mechanism is not fully known...
2017: Biotechnology for Biofuels
Liang Tian, Skyler J Perot, David Stevenson, Tyler Jacobson, Anthony A Lanahan, Daniel Amador-Noguez, Daniel G Olson, Lee R Lynd
Background: Clostridium thermocellum is a promising microorganism for conversion of cellulosic biomass to biofuel, without added enzymes; however, the low ethanol titer produced by strains developed thus far is an obstacle to industrial application. Results: Here, we analyzed changes in the relative concentration of intracellular metabolites in response to gradual addition of ethanol to growing cultures. For C. thermocellum, we observed that ethanol tolerance, in experiments with gradual ethanol addition, was twofold higher than previously observed in response to a stepwise increase in the ethanol concentration, and appears to be due to a mechanism other than mutation...
2017: Biotechnology for Biofuels
Angelo G Peralta, Sivasankari Venkatachalam, Sydney C Stone, Sivakumar Pattathil
Background: Xylan is a major hemicellulosic component in the cell walls of higher plants especially in the secondary walls of vascular cells which are playing important roles in physiological processes and overall mechanical strength. Being the second most abundant cell wall polymer after cellulose, xylan is an abundant non-cellulosic carbohydrate constituent of plant biomass. Xylan structures have been demonstrated to contribute to plant biomass recalcitrance during bioenergy applications...
2017: Biotechnology for Biofuels
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