| 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. |
- Chang, Haigang, et al.
(författare)
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Continuous High Frequency Deep Brain Stimulation of the Rat Anterior Insula Attenuates the Relapse Post Withdrawal and Strengthens the Extinction of Morphine Seeking
- 2020
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Ingår i: Frontiers in Psychiatry. - : Frontiers Media SA. - 1664-0640. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Deep brain stimulation (DBS) modulates the neuronal activity in specific brain circuits and has been recently considered as a promising intervention for refractory addiction. The insula cortex is the hub of interoception and is known to be involved in different aspects of substance use disorder. In the present study, we investigate the effects of continuous high frequency DBS in the anterior insula (AI) on drug-seeking behaviors and examined the molecular mechanisms of DBS action in morphine-addicted rats. Sprague-Dawley rats were trained to the morphine-conditioned place preference (CPP, day 1-8) followed by bilaterally implanted with DBS electrodes in the AI (Day 10) and recovery (Day 10-15). Continuous high-frequency (HF) -DBS (130 Hz, 150 mu A, 90 mu s) was applied during withdrawal (Day 16-30) or extinction sessions. CPP tests were conducted on days 16, 30, 40 during withdrawal session and several rats were used for proteomic analysis on day 30. Following the complete extinction, morphine-CPP was reinstated by a priming dose of morphine infusion (2 mg/kg). The open field and novel objective recognition tests were also performed to evaluate the DBS side effect on the locomotion and recognition memory. Continuous HF-DBS in the AI attenuated the expression of morphine-CPP post-withdrawal (Day 30), but morphine addictive behavior relapsed 10 days after the cessation of DBS (Day 40). Continuous HF-DBS reduced the period to full extinction of morphine-CPP and blocked morphine priming-induced recurrence of morphine addiction. HF-DBS in the AI had no obvious effect on the locomotor activity and novel objective recognition and did not cause anxiety-like behavior. In addition, our proteomic analysis identified eight morphine-regulated proteins in the AI and their expression levels were reversely changed by HF-DBS. Continuous HF-DBS in the bilateral anterior insula prevents the relapse of morphine place preference after withdrawal, facilitates its extinction, blocks the reinstatement induced by morphine priming and reverses the expression of morphine-regulated proteins. Our findings suggest that manipulation of insular activity by DBS could be a potential intervention to treat substance use disorder, although future research is warranted.
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| 3. |
- Chen, Cheng, et al.
(författare)
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Performance of multiple satellite precipitation estimates over a typical arid mountainous area of China : Spatiotemporal patterns and extremes
- 2020
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Ingår i: Journal of Hydrometeorology. - 1525-755X. ; 21:3, s. 533-550
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Tidskriftsartikel (refereegranskat)abstract
- Precipitation in arid mountainous areas is characterized by low rainfall intensity and large spatial heterogeneity, which challenges satellite-based monitoring by the spaceborne sensors. This study aims to comparatively evaluate the detection ability of spatiotemporal patterns and extremes of rainfall by a range of mainstream satellite precipitation products [TMPA, Climate Hazards Group Infrared Precipitation with Station Data (CHIRPS), and PERSIANN-Climate Data Record (PERSIANN-CDR)] over a typical arid mountainous basin of China, benchmarking against rain gauge data from 2000 to 2015. Results showed that satellite precipitation estimates had relatively low accuracy at the daily scale, while a significant improvement of correlation coefficient (CC;>0.6) and a significant reduction of relative root-mean-square error (RRMSE;, 1.0) were found as time scale increases beyond the monthly scale. CHIRPS tended to overestimate the gauge precipitation with positive relative bias (RB), while the negative RBvalues for TMPAand PERSIANN-CDR indicated there was an underestimation. CHIRPS had the most similar spatial pattern and slope trends of the seasonal precipitation and interannual variations of annual precipitation with gauge observations. With the increase in rainfall rates, the probability of detection (POD) and critical success index (CSI) were reduced and the false alarm ratio (FAR) was increased significantly, demonstrating the limited capability for all the three satellite products for detecting heavy rainfall events. CHIRPS showed the best performance in detecting rainfall extremes compared to TMPA and PERSIANN-CDR, evidenced by the largerCSI values and similar extreme rainfall indices obtained from gauge records. This study provides valuable guidance for choosing satellite precipitation products instead of gauge observations for rainfall monitoring (especially rainfall extremes) and agricultural production management over arid mountainous area.
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| 4. |
- Guo, Shize, et al.
(författare)
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Securing IoT Space via Hardware Trojan Detection
- 2020
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Ingår i: IEEE Internet of Things Journal. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2327-4662. ; 7:11, s. 11115-11122
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Tidskriftsartikel (refereegranskat)abstract
- Hardware Trojan (HT) is a malicious modification in the chip circuitry, which may lead to undesired chip function changing or sensitive information leaking once activated. As recently studied, HT has become one of the main threats for Internet-of-Things (IoT) security, and therefore, protecting IoT against the HT attack attracts growing attention from IoT researchers. In this article, we propose an HT detection technique which makes use of chip temporal thermal information and self-organizing map (SOM) neural network to automatically isolate the Trojan-infected chips with the Trojan-free ones, and meanwhile, confirm the Trojan location at the infected chips. The experimental results reveal that our method is effective. Specifically, for the Trust-hub benchmarks, it can detect HTs which increase only 0.02% power consumption of the original design and localize the Trojan positions precisely without any error. In addition, we demonstrate the advantages of our method over two existing HT detection methods, namely, the thermal and power map (TPM) and ring oscillator net (RON), and make a thorough discussion on how the thermal image resolution, chip technology, and clustering algorithm affect the Trojan detection results.
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| 5. |
- Guo, Xiaoxian, et al.
(författare)
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Understand the genomic diversity and evolution of fungal pathogen Candida glabrata by genome-wide analysis of genetic variations
- 2020
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Ingår i: Methods. - : Elsevier BV. - 1095-9130 .- 1046-2023. ; 176, s. 82-90
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Tidskriftsartikel (refereegranskat)abstract
- The yeast Candida glabrata, an opportunistic human fungal pathogen, is the second most prevalent cause of candidiasis worldwide, with an infection incidence that has been increasing in the past decades. The completion of the C. glabrata reference genome made fundamental contributions to the understanding of the molecular basis of its pathogenic phenotypes. However, knowledge of genome-wide genetic variations among C. glabrata strains is limited. In this study, we present a population genomic study of C. glabrata based on whole genome re-sequencing of 47 clinical strains to an average coverage of ∼63×. Abundant genetic variations were identified in these strains, including single nucleotide polymorphisms (SNPs), small insertion/deletions (indels) and copy number variations (CNVs). The observed patterns of variations revealed clear population structure of these strains. Using population genetic tests, we detected fast evolution of several genes involved in C. glabrata adherence ability, such as EPA9 and EPA10. We also located genome structural variations, including aneuploidies and large fragment CNVs, in regions that are functionally related to virulence. Subtelometric regions were hotspots of CNVs, which may contribute to variation in expression of adhesin genes that are important for virulence. We further conducted a genome-wide association study that identified two SNPs in the 5′UTR region of CST6 that were associated with fluconazole susceptibility. These observations provide convincing evidence for the highly dynamic nature of the C. glabrata genome with potential adaptive evolution to clinical environments, and offer valuable resources for investigating the mechanisms underlying drug resistance and virulence in this fungal pathogen. (249 words)
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| 6. |
- Liang, Xifeng, et al.
(författare)
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On the aerodynamic loads when a high speed train passes under an overhead bridge
- 2020
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 202
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Tidskriftsartikel (refereegranskat)abstract
- The aerodynamic loads on the overhead bridge bottom surface induced by train passage are reported in this paper. Both moving model test and numerical simulation approaches at the 1:20 scale are used. The numerical work is validated through both mesh independence tests and comparison with experimental data. Typical pressure variation curves are plotted and compared with previous studies. The peak pressure values’ dependence on the Reynolds number is considered through four sets of experiments with different train running speeds. The peak pressure coefficient distribution law for the bridge bottom surface is presented. Differences in the pressure distribution in different bridge bottom areas are explained based on more detailed flow field information. The influence of the bridge height on the aerodynamic load magnitude and time interval is presented. Moreover, the application of the CEN Standard to practical engineering issues is discussed.
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| 7. |
- Liu, Shenhai, et al.
(författare)
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The Glucagon-Like Peptide-1 Analogue Liraglutide Reduces Seizures Susceptibility, Cognition Dysfunction and Neuronal Apoptosis in a Mouse Model of Dravet Syndrome
- 2020
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Ingår i: Frontiers in Pharmacology. - : Frontiers Media SA. - 1663-9812. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Dravet syndrome (DS) is a refractory epilepsy typically caused by heterozygous mutations of the Scn1a gene, which encodes the voltage-gated sodium channel Nav1.1. Glucagon-like peptide-1 (GLP-1) analogues, effective therapeutic agents for the treatment of diabetes, have recently become attractive treatment modalities for patients with nervous system disease; however, the impact of GLP-1 analogues on DS remains unknown. This study aimed to determine the neuroprotective role of liraglutide in mouse and cell models of Scn1a KO-induced epilepsy. Epileptic susceptibility, behavioral changes, and behavioral seizures were assessed using electroencephalography (EEG), IntelliCage (TSE Systems, Bad Homburg, Germany), and the open field task. Morphological changes in brain tissues were observed using hematoxylin and eosin (HE) and Nissl staining. Expression of apoptosis-related proteins and the mammalian target of rapamycin (mTOR) signaling pathway were determined using immunofluorescence and western blotting in Scn1a KO-induced epileptic mice in vitro. Scn1a KO model cell proliferation was evaluated using the Cell Counting Kit-8 assay, and the effect of liraglutide on cellular apoptosis levels was examined using Annexin V-FITC/PI flow cytometry. Apoptotic signal proteins and mTOR were assessed using reverse transcription - quantitative polymerase chain reaction (RT-qPCR) and western blotting. Our results showed that liraglutide significantly increased mRNA ((0.31 ± 0.04) *10-3 vs. (1.07 ± 0.08) * 10-3, P = 0.0004) and protein (0.10 ± 0.02 vs. 0.27 ± 0.02, P = 0.0006) expression of Scn1a in Scn1a KO-induced epileptic mice. In addition, liraglutide significantly alleviated electroencephalographic seizures, the severity of responses to epileptic seizures (96.53 ± 0.45 % vs. 85.98 ± 1.24 %, P = 0.0003), cognitive dysfunction, and epileptic-related necrotic neurons (9.76 ± 0.91 % vs. 19.65 ± 2.64 %, P = 0.0005) in Scn1a KO-induced epileptic mice. Moreover, liraglutide protected against Scn1a KO-induced apoptosis, which was manifested in the phosphorylation of mTOR (KO+NS: 1.99 ± 0.31 vs. KO+Lira: 0.97 ± 0.18, P = 0.0004), as well as the downregulation of cleaved caspase-3 (KO+NS: 0.49 ± 0.04 vs. KO+Lira: 0.30 ± 0.01, P = 0.0003) and restoration of the imbalance between BAX (KO+NS: 0.90 ± 0.02 vs. KO+Lira: 0.75 ± 0.04, P = 0.0005) and BCL-2 (KO+NS: 0.46 ± 0.02 vs. KO+Lira: 0.61 ± 0.02, P = 0.0006). Collectively, these results show that liraglutide reduces seizure susceptibility and cognitive dysfunction in the mouse model of Dravet syndrome, and exerts anti-apoptotic and neuroprotective effects in Scn1a KO mice and cells.
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| 8. |
- Shen, Minhao, et al.
(författare)
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Effects of exposure time and printing angle on the curing characteristics and flexural strength of ceramic samples fabricated via digital light processing
- 2020
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 46:15, s. 24379-24384
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Tidskriftsartikel (refereegranskat)abstract
- The development of photosensitive slurries for additive manufacturing has attracted great interest due to their correlation with the final properties of the fabricated parts. This paper focus on the printing quality control in digital light processing (DLP) 3D printing of advanced ceramics. Systematic experiments were performed to assess the effects of the exposure time and printing angle on the three-point bending strength of the fabricated samples. The exposure time affected the bending strength of the printed zirconia ceramic dramatically. When the weak exposure time is 1 s and the strong exposure time is 13 s, the average bending strength can reach 580 MPa while Weibull modulus can reach 8.84. Meanwhile, the printing angle also affected the bending strength mechanical sample printed at 45 degrees exhibits the worst performance.
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| 9. |
- Wang, Zhe, et al.
(författare)
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Moving model test of the smoke movement characteristics of an on-fire subway train running through a tunnel
- 2020
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798. ; 96
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Tidskriftsartikel (refereegranskat)abstract
- A moving model test was carried out to investigate the associated smoke movement characteristics when a subway train on fire runs in a tunnel. Train models of the 1/10 and 1/15 scales were used. The spatial distributions of airflow velocity and smoke concentration were then analyzed, and the differences between moving fire sources and stationary fire sources were discussed. The results show that the smoke movement characteristics of a stationary fire source were greatly different from those of a moving one. Specifically, the smoke movement for the moving fire source was dominated by piston wind. Moreover, the process of the smoke spread could be divided into three stages, during which time the flow direction changed. The peak smoke concentration value occurred after the train tail passed by the measuring point. Besides, the impacts of train speed (60 km/h, 80 km/h, 100 km/h, and 120 km/h) and blockage ratio (0.19 and 0.43) on airflow velocity and smoke concentration were also investigated. With increasing train velocity, the airflow velocity increased, and the smoke concentration decreased. The maximum airflow velocity was approximately linear with the train velocity. Furthermore, the increasing blockage ratio enhanced the piston effect in the tunnel, thus increasing the airflow velocity and reducing the smoke concentration.
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| 10. |
- Wang, Zhe, et al.
(författare)
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Numerical Investigation on Thermal Performance Design of Cryogenic Compact Heat Exchangers with Serrated-Fin Channels
- 2020
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Ingår i: Heat Transfer Engineering. - : Informa UK Limited. - 0145-7632 .- 1521-0537. ; 41, s. 1856-1868
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Tidskriftsartikel (refereegranskat)abstract
- Traditional empirical formulas of Colburn heat transfer factors will lead to a design deviation for cryogenic heat exchangers. This paper employs the computational fluid dynamics (CFD) technique to numerically study the thermal performance of cryogenic compact heat exchangers (CCHEs). To obtain more precise convective heat transfer coefficients, the heat transfer performance of CCHE with serrated fin channels is analyzed considering various cryogenic fluid properties, fin materials and the axial heat conduction (AHC), and a heat transfer deterioration rate is proposed to investigate the effect of AHC on the heat transfer performance of CCHEs. For the simulation design, a quasi-one-dimensional calculation model is developed to obtain the temperature and pressure fields of the whole heat exchanger using the previous CFD results of the finned channels to avoid the deviation caused by traditional empirical formulas. Finally, a case study for a CCHE in a practical system is designed and analyzed by the proposed approach. The results suggest that cryogenic conditions have a significant effect on the design performance of heat exchangers, especially when considering the influences of fluid properties, materials, and AHC. For different cryogenic fluids, accurate heat transfer factors should be selected for the design calculations, and materials with high thermal conductivity will increase the effect of AHC and deteriorate the performance of the CCHE.
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