| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Cai, Tingting, et al.
(författare)
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Human cortical neural correlates of visual fatigue during binocular depth perception : An fNIRS study
- 2017
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- Functional near-infrared spectroscopy (fNIRS) was adopted to investigate the cortical neural correlates of visual fatigue during binocular depth perception for different disparities (from 0.1 degrees to 1.5 degrees). By using a slow event-related paradigm, the oxyhaemoglobin (HbO) responses to fused binocular stimuli presented by the random-dot stereogram (RDS) were recorded over the whole visual dorsal area. To extract from an HbO curve the characteristics that are correlated with subjective experiences of stereopsis and visual fatigue, we proposed a novel method to fit the time-course HbO curve with various response functions which could reflect various processes of binocular depth perception. Our results indicate that the parietal-occipital cortices are spatially correlated with binocular depth perception and that the process of depth perception includes two steps, associated with generating and sustaining stereovision. Visual fatigue is caused mainly by generating stereovision, while the amplitude of the haemodynamic response corresponding to sustaining stereovision is correlated with stereopsis. Combining statistical parameter analysis and the fitted time-course analysis, fNIRS could be a promising method to study visual fatigue and possibly other multi-process neural bases.
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| 4. |
- Chang, Lin, et al.
(författare)
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Multi-surface phase-shifting algorithm using the window function fitted by the nonlinear least squares method
- 2022
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Ingår i: Journal of Modern Optics. - : TAYLOR & FRANCIS LTD. - 0950-0340 .- 1362-3044. ; 69:3, s. 160-171
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Tidskriftsartikel (refereegranskat)abstract
- A multi-surface phase demodulation algorithm is proposed to measure surfaces of the transparent plate simultaneously. A non-linear least-squares method based on the trust region is utilized to fit the window function derived from the characteristic polynomials. The fitted window function requires fewer parameters and has a flexible form, which means the window length can be stretched freely and used flexibly. Then, a multi-surface phase demodulation technique combining the discrete Fourier principle and the fitted window function is investigated, allowing simultaneous reconstruction of the measured front surface, rear surface, and thickness variation. During the implementation of our algorithm, the processing time for the interferograms with 850x850 pixels is around 5.1s. Measurement errors caused by several factors are analyzed, including wavelength-tuning error, frequency order error, cavity length error, and average thickness error. The experimental result on a rectangular transparent plate further verifies the effectiveness of our algorithm.
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| 5. |
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| 6. |
- Daranciang, Dan, et al.
(författare)
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Ultrafast Photovoltaic Response in Ferroelectric Nanolayers
- 2012
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Ingår i: Physical Review Letters. - 1079-7114. ; 108:8
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Tidskriftsartikel (refereegranskat)abstract
- We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond time scales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.
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| 7. |
- Hu, Jiandong, et al.
(författare)
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Development of a Surface Plasmon Resonance Biosensing Approach for the Rapid Detection of Porcine Circovirus Type2 in Sample Solutions
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:10, s. e111292-
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Tidskriftsartikel (refereegranskat)abstract
- A sensitive and label-free analytical approach for the detection of porcine circovirus type 2 (PCV2) instead of PCV2 antibody in serum sample was systematically investigated in this research based on surface plasmon resonance (SPR) with an establishment of special molecular identification membrane. The experimental device for constructing the biosensing analyzer is composed of an integrated biosensor, a home-made microfluidic module, and an electrical control circuit incorporated with a photoelectric converter. In order to detect the PCV2 using the surface plasmon resonance immunoassay, the mercaptopropionic acid has been used to bind the Au film in advance through the known form of the strong S-Au covalent bonds formed by the chemical radical of the mercaptopropionic acid and the Au film. PCV2 antibodies were bonded with the mercaptopropionic acid by covalent -CO-NH- amide bonding. For the purpose of evaluating the performance of this approach, the known concentrations of PCV2 Cap protein of 10 mu g/mL, 7.5 mu g/mL, 5 mu g/mL, 2.5 mu g/mL, 1 mu g/mL, and 0.5 mu g/mL were prepared by diluting with PBS successively and then the delta response units (Delta RUs) were measured individually. Using the data collected from the linear CCD array, the Delta RUs gave a linear response over a wide concentration range of standard known concentrations of PCV2 Cap protein with the R-Squared value of 0.99625. The theoretical limit of detection was calculated to be 0.04 mu g/mL for the surface plasmon resonance biosensing approach. Correspondingly, the recovery rate ranged from 81.0% to 89.3% was obtained. In contrast to the PCV2 detection kits, this surface plasmon resonance biosensing system was validated through linearity, precision and recovery, which demonstrated that the surface plasmon resonance immunoassay is reliable and robust. It was concluded that the detection method which is associated with biomembrane properties is expected to contribute much to determine the PCV2 in sample solutions instead of PCV2 antibody in serum samples quantitatively.
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| 8. |
- Jin, Tingting, et al.
(författare)
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Efficient heterogeneous integration of InP/Si and GaSb/Si templates with ultra-smooth surfaces
- 2022
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Ingår i: Science China Information Sciences. - : Springer Science and Business Media LLC. - 1869-1919 .- 1674-733X. ; 65:8
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Tidskriftsartikel (refereegranskat)abstract
- Heterogeneous integration of InP and GaSb on Si substrates holds a huge potential interest in near-infrared and mid-infrared optoelectronic devices. In this study, 2-inch 180-nm-thick InP and 185-nm-thick GaSb thin layers were successfully transferred onto the Si substrates to form high-quality and ultra-smooth InP/Si and GaSb/Si templates using molecular beam epitaxy (MBE) and the ion-slicing technique together with selective chemical etching. The relocation of the implantation-introduced damage in the sacrificial layer enables the transfer of relatively defect-free InP and GaSb thin films. The sacrificial layers were completely etched off by selective chemical etching, leaving ultra-smooth epitaxial surfaces with a roughness of 0.2 nm for the InP/Si template and 0.9 nm for the GaSb/Si template, respectively. Thus, the chemical mechanical polishing (CMP) process was not required to smooth the surface which usually introduces particles and chemical contaminations on the transferred templates. Furthermore, the donor substrate is not consumed and can be recycled to reduce the cost, which provides a paradigm for the sustainable and economic development of the Si integration platform.
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| 9. |
- Jin, Taiyi, et al.
(författare)
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Osteoporosis and renal dysfunction in a general population exposed to cadmium in China.
- 2004
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Ingår i: Environmental research. - : Elsevier BV. - 0013-9351. ; 96:3, s. 353-9
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Tidskriftsartikel (refereegranskat)abstract
- Osteoporosis is a common metabolic disease characterized by low bone mass and microarchitectural deterioration of bone tissue. Many factors are involved in the occurrence of osteoporosis. Cadmium can cause both osteomalacia and osteoporosis and these effects have long been investigated through various epidemiological or experimental studies. The present study examines a possible relationship between cadmium nephropathy and its effects on the skeleton in populations living in a polluted area in southeast China. Monophoton absorptiometry was used to measure bone mineral density in the population and the Z score (the number of SD from the difference between the measured bone density of the individual and the group mean value for sex- and age-matched controls) was introduced to define osteoporosis (Z score < -2). Osteoporosis caused by cadmium exposure was demonstrated in this study on a general population environmentally exposed to cadmium in China. It was found that there were significant differences in the prevalence of osteoporosis among the different urinary cadmium groups (chi2 = 18.84, P = 0.0008). The linear trend test gave chi2 = 16.281, P = 0.00005. There was a dose-response relationship between cadmium exposure (urinary cadmium) and prevalence of osteoporosis. Of 31 subjects with osteoporosis, 23 subjects were suffering from renal dysfunction. The prevalence of renal dysfunction (74.19%) was significantly higher than that in those without osteoporosis (chi2 = 16.53, P < 0.001). Stratum analysis was performed to further assess the relationship between bone damage and renal impairment caused by cadmium. There was a significant difference between those with and without tubular damage (chi2 = 19.92, P = 0.000) but not in those with and without glomerular damage (chi2 = 0.08, P = 0.114). This showed that glomerular dysfunction plays a smaller role than tubular dysfunction in the causation of bone damage. It was found that the prevalence of osteoporosis increases with increasing values of parameters of tubular damage. Osteoporosis caused by cadmium is thus related to kidney dysfunction and especially to tubular damage and its severity but not to glomerular damage. The present study has thus demonstrated the combined adverse effects (osteoporosis and renal dysfunction) caused by environmental exposure to cadmium for the first time in Asia outside the endemic area in Japan.
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| 10. |
- Li, Qizhao, et al.
(författare)
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Regioselectively Halogenated Expanded Porphyrinoids as Building Blocks for Constructing Porphyrin-Porphyrinoid Heterodyads with Tunable Energy Transfer
- 2019
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 141:13, s. 5294-5302
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Tidskriftsartikel (refereegranskat)abstract
- Expanded porphyrins have been attracting increasing attention owing to their unique optical and electrochemical properties as well as switchable aromaticity. Toward material applications, regioselective functionalization of the expanded porphyrins at their periphery is indeed challenging due to the presence of multiple reactive sites. Herein, a set of regioselective halogenated isomers (L5-Br-A/B/C) of neo-confused isosmaragdyrin (L5) are synthesized by a combination of the halogenation reaction of L5 and sequential macrocycleto-macrocycle transformation reactions of its halogenated isomers. On this basis, the regioselectively functionalized isosmaragdyrins are utilized as building blocks for constructing multichromophoric porphyrinoids, specifically, heterodyads L5-ZnP-A/B/C, in which a common zinc porphyrin is linked at three different pyrrolic positions of isosmaragdyrins, respectively, by Sonogashira coupling reactions. The highly efficient energy cascade from porphyrin to isosmaragdyrin is elucidated using steady-state/time-resolved spectroscopies and theoretical calculations. Notably, the energy transfer processes from the porphyrin to the isosmaragdyrin moieties as well as the excitation energy transfer rates in L5-ZnP-A/B/C are highly dependent on the linking sites by through-bond and Forster-type resonance energy transfer mechanisms. The site-selective functionalization and subsequent construction of a set of heterodyads of the expanded porphyrinoid would provide opportunities for developing new materials for optoelectronic applications.
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