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排序方式: 共有294条查询结果,搜索用时 15 毫秒
41.
Camilla Chua Soo Leng Badlishah Sham Baharin Yaakob Che Man Chin Ping Tan 《Journal of the science of food and agriculture》2008,88(9):1512-1517
BACKGROUND: Squalene was concentrated from palm fatty acid distillate (PFAD) in this study using commercial immobilised Candida antarctica lipase (Novozyme 435®). The PFAD was neutralised (NPFAD) using an alkali to liberate the free fatty acids and then hydrolysed at 65 ± 1 °C. The enzymatic hydrolysis on NPFAD was optimised using response surface methodology (RSM) before being neutralised again to obtain a concentrated squalene fraction. RESULTS: A five‐level, three‐factor central composite rotatable design was adopted to evaluate the effects of the enzymatic hydrolysis parameters reaction time (4–12 h), water content (50–70% w/w) and enzyme concentration (1.5–3.5% w/w) on the percentage yield of squalene concentration. The optimal reaction parameters for maximum yield of squalene concentration were identified from the respective contour plots. The optimal enzymatic hydrolysis conditions were a reaction time of 7.05 h, a water content of 61.40% w/w and an enzyme concentration of 2.23% w/w. CONCLUSION: RSM was used to determine the optimal conditions for enzymatic hydrolysis of NPFAD with C. antarctica lipase for maximum recovery of squalene which could be implemented on an industrial scale. Copyright © 2008 Society of Chemical Industry 相似文献
42.
Sabrina Vantadori Andrea Carpinteri Karolina Gowacka Fabrizio Greco Tomasz Osiecki Camilla Ronchei Andrea Zanichelli 《Fatigue & Fracture of Engineering Materials & Structures》2021,44(1):3-13
By examining the state of the art, it can be realised that few research works have been done on the fracture behaviour of plastic composites reinforced with continuous glass fibres. Therefore, the present paper deals with the fracture toughness of a unidirectional glass fibre‐reinforced plastic (GFRP), such a parameter being analytically determined by means of the modified two‐parameter model (MTPM). The input data of the MTPM are obtained from an experimental campaign related to three‐point bending tests on single edge‐notched specimens characterised by different sizes. The novelty of this research work is that the MTPM, originally proposed for isotropic materials, is here employed to estimate the fracture toughness of GFRPs characterised by orthotropic mechanical properties. 相似文献
43.
Daniel Jönsson Albin Bergström Camilla Forsell Rozalyn Simon Maria Engström Susanna Walter Anders Ynnerman Ingrid Hotz 《Computer Graphics Forum》2020,39(6):392-407
We present an application, and its development process, for interactive visual analysis of brain imaging data and clinical measurements. The application targets neuroscientists interested in understanding the correlations between active brain regions and physiological or psychological factors. The application has been developed in a participatory design process and has subsequently been released as the free software ‘VisualNeuro’. From initial observations of the neuroscientists' workflow, we concluded that while existing tools provide powerful analysis options, they lack effective interactive exploration requiring the use of many tools side by side. Consequently, our application has been designed to simplify the workflow combining statistical analysis with interactive visual exploration. The resulting environment comprises parallel coordinates for effective overview and selection, Welch's t-test to filter out brain regions with statistically significant differences and multiple visualizations for comparison between brain regions and clinical parameters. These exploration concepts enable neuroscientists to interactively explore the complex bidirectional interplay between clinical and brain measurements and easily compare different patient groups. A qualitative user study has been performed with three neuroscientists from different domains. The study shows that the developed environment supports simultaneous analysis of more parameters, provides rapid pathways to insights and is an effective tool for hypothesis formation. 相似文献
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45.
Isabella De Bellis Daniele Martella Camilla Parmeggiani Diederik Sybolt Wiersma Sara Nocentini 《Advanced functional materials》2023,33(39):2213162
Photonic crystals owe their multitude of optical properties to the way their structure creates interference effects. It is therefore possible to influence the photonic response by acting on their physical structure. In this article, tunable photonic crystals made by elastic polymers that respond to their environment are explored, in particular with a physical deformation under temperature variation. This creates a feedback process in which the photonic response depends on its physical structure, which itself is influenced by the environmental changes. By using a multi-photon polymerization process specifically optimized for soft responsive polymers such as Liquid Crystalline Networks, highly resolved, reproducible, and mechanically self-standing photonic crystals are fabricated. The physical structure of the 3D woodpile can be tuned by an external temperature variation creating a reversible spectral tuning of 50 nm in the telecom wavelength range. By comparing these results with finite element calculations and temperature induced shape-change, it is confirmed that the observed tuning is due to an elastic deformation of the structure. The achieved nanometric patterning of tunable anisotropic photonic materials will further foster the development of reconfigurable photonic crystals with point defects acting as tunable resonant cavities and, more in general, of 4D nanostructures. 相似文献
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47.
Conventional Fourier transform infrared (FT-IR) spectroscopy and microscopy have been widely used in forensic science. New opportunities exist to obtain chemical images and to enhance the spatial resolution using attenuated total reflection (ATR) FT-IR spectroscopy coupled with a focal-plane array (FPA) detector. In this paper, the sensitivity limits of FT-IR imaging using three different ATR crystals (Ge, ZnSe, and diamond) in three different optical arrangements for the detection of model particles is discussed. Model systems of ibuprofen and paracetamol particles having sizes below 32 mum were studied. The collection of drug particles was achieved with the aid of two different tapes: common adhesive tape and a film of polydimethylsiloxane (PDMS). The surface of the film with collected particles was measured directly via ATR-FT-IR imaging. Since the removal of tape from porous surfaces can be difficult, the application of micro ATR-FT-IR imaging directly to the surface of a newspaper contaminated with particles of model drugs is also discussed. In order to assess the feasibility of the chosen method in a forensic case study, the detection of diacetylmorphine hydrochloride traces in PDMS matrix and the finger surface is investigated. The scenarios considered were that of the detection of evidence collected at a crime scene with the tape lift method and the analysis of the finger of an individual after drug handling. The results show broad implications in the detection of drugs of abuse. 相似文献
48.
49.
Organochlorine compounds in Lake Superior: chiral polychlorinated biphenyls and biotransformation in the aquatic food web 总被引:1,自引:0,他引:1
Wong CS Mabury SA Whittle DM Backus SM Teixeira C DeVault DS Bronte CR Muir DC 《Environmental science & technology》2004,38(1):84-92
The enantiomeric composition of seven chiral PCB congeners was measured in the Lake Superior aquatic food web sampled in 1998, to determine the extent of enantioselective biotransformation in aquatic biota. All chiral PCB congeners studied (CBs 91, 95, 136, 149, 174, 176, and 183) biomagnified in the Lake Superior aquatic food web, based on biomagnification and food web magnification factors greater than unity. PCB atropisomers were racemic in phytoplankton and zooplankton, suggesting no biotransformation potential toward PCBs for these low trophic level organisms. However, Diporeia and mysids had significantly nonracemic residues for most chiral congeners studied. This observation suggests that these macrozooplankton can stereoselectively metabolize chiral congeners. Alternatively, macrozooplankton obtained nonracemic residues from feeding on organic-rich suspended particles and sediments, which would imply that stereoselective microbial PCB biotransformation may be occurring in Lake Superior sediments at PCB concentrations far lower than that previously associated with such activity. Widely nonracemic PCB residues in forage fish (lake herring, rainbow smelt, and slimy sculpin) and lake trout suggest a combination of both in vivo biotransformation and uptake of nonracemic residues from prey for these species. Minimum biotransformation rates, calculated from enantiomer mass balances between predators and prey, suggest metabolic half-lives on the order of 8 yr for CB 136 in lake trout and 2.6 yr for CB 95 in sculpins. This result suggests that significant biotransformation may occur for metabolizable PCB congeners over the lifespan of these biota. This study highlights the potential of chiral analysis to study biotransformation processes in food webs. 相似文献
50.
Morten E. Simonsen Camilla S?nderby Zheshen Li Erik G. S?gaard 《Journal of Materials Science》2009,44(8):2079-2088
This article presents the results of an investigation of the compositional and structural features of an inorganic polymer
synthesized from amorphous silica and KOH. The inorganic polymers were characterized using Fourier transformation infrared
spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD).
FT-IR investigation of the inorganic polymers showed that an increase in the hydroxide concentration used in the synthesis
shifts the position of the maximum absorbance of Si–O bands toward lower wave numbers, indicating the transformation of Q4 units to Q3 and Q2 units. XPS investigation of the inorganic polymers showed that the total amount of oxygen and potassium present in the sample
increased when higher concentrations of hydroxide were used in the synthesis. The O/Si ratio of the inorganic polymers changed
from 2 to 2.6 when the KOH concentration was increased from 0.75 to 4 M. The increase in the O/Si ratio can be explained by
the greater dissolution of SiO2 particles leading to the formation of branched polymers and gelation. 相似文献