35 research outputs found
A prediction-correction based iterative convolution-thresholding method for topology optimization of heat transfer problems
In this paper, we propose an iterative convolution-thresholding method (ICTM)
based on prediction-correction for solving the topology optimization problem in
steady-state heat transfer equations. The problem is formulated as a
constrained minimization problem of the complementary energy, incorporating a
perimeter/surface-area regularization term, while satisfying a steady-state
heat transfer equation. The decision variables of the optimization problem
represent the domains of different materials and are represented by indicator
functions. The perimeter/surface-area term of the domain is approximated using
Gaussian kernel convolution with indicator functions. In each iteration, the
indicator function is updated using a prediction-correction approach. The
prediction step is based on the variation of the objective functional by
imposing the constraints, while the correction step ensures the monotonically
decreasing behavior of the objective functional. Numerical results demonstrate
the efficiency and robustness of our proposed method, particularly when
compared to classical approaches based on the ICTM.Comment: 29 pages, 25 figure
Improving the Lot Fabrication Stability and Performance of Silica Optical Films during PECVD
Silica optical film specifications are determined by their processing capability and their fabrication stability. Here, a statistical process control (SPC) approach usually used in planar lightwave circuits (PLC) is adopted to analyze the stability of the silica optical film fabrication process. Apart from the raw materials, certain key external factors have to be taken into consideration during the PLC process, such as temperature, relative humidity, process variation and machine aging. The fabrication process can be adjusted according to SPC-based results in real-time, so as to produce high quality silica optical film. By using this method, it is possible to assess the effectiveness of older production lines and extend their production capacity at minimal cost
The importance of biofilm contamination control for dental unit waterlines: a multicenter assessment of the microbiota diversity of biofilm in dental unit waterlines
ABSTRACTBackground The biofilm formation in Dental Unit Waterlines (DUWLs) could become an important cause of infection during dental care, which could put immunocompromised individuals at risk of cross-infection. The aim of this study was to characterize the microbial communities of biofilms among DUWLs using high-throughput sequencing technology.Methods Twenty-nine biofilm samples were obtained from 24 dental chair units at 5 hospitals and 2 dental clinics. The genomic DNA of the samples was extracted, then 16S rDNA and ITS2 gene were amplified and sequenced. Alpha-diversity and Beta-diversity were calculated with QIIME2 and the Kruskal – Wallis H-test was adopted for statistical analysis.Results Microbial communities with a high diversity of bacteria (377 genera) and fungi (83 genera) were detected in the biofilm samples. The dominant phylum of bacteria was Proteobacteria (93.27%) and that of fungi was Basidiomycota (68.15%). Potential human pathogens were detected including 7 genera of bacteria (Pseudomonas, Stenotrophomonas, Hafnia-Obesumbacterium, Burkholderia-Caballeronia-Paraburkholderia, Ralstonia, Enterobacter, Klebsiella) and 6 genera of fungi (Malassezia, Candida, Alternaria, Cryptococcus, Rhodotorula, Rhinocladiella).Conclusions This multicenter assessment revealed the infectious risk during dental care. It emphasized the importance of biofilm control due to biofilm accumulation and multiple kinds of opportunistic pathogens in DUWLs
Proteome and Glycoproteome Analyses Reveal the Protein N-Linked Glycosylation Specificity of STT3A and STT3B
STT3A and STT3B are the main catalytic subunits of the oligosaccharyltransferase complex (OST-A and OST-B in mammalian cells), which primarily mediate cotranslational and post-translocational N-linked glycosylation, respectively. To determine the specificity of STT3A and STT3B, we performed proteomic and glycoproteomic analyses in the gene knock-out (KO) and wild-type HEK293 cells. In total, 3961 proteins, 4265 unique N-linked intact glycopeptides and 629 glycosites representing 349 glycoproteins were identified from all these cells. Deletion of the STT3A gene had a greater impact on the protein expression than deletion of STT3B, especially on glycoproteins. In addition, total mannosylated N-glycans were reduced and fucosylated N-glycans were increased in STT3A-KO cells, which were caused by the differential expression of glycan-related enzymes. Interestingly, hyperglycosylated proteins were identified in KO cells, and the hyperglycosylation of ENPL was caused by the endoplasmic reticulum (ER) stress due to the STT3A deletion. Furthermore, the increased expression of the ATF6 and PERK indicated that the unfolded protein response also happened in STT3A-KO cells. Overall, the specificity of STT3A and STT3B revealed that defects in the OST subunit not only broadly affect N-linked glycosylation of the protein but also affect protein expression
In vivo acquisition of blaKPC-2 with low biological cost in blaAFM-1-harboring ST463 hypervirulent Pseudomonas aeruginosa from a patient with hematologic malignancy
ABSTRACT: Objectives: Klebsiella pneumoniae carbapenemase (KPC)–producing sequence type (ST) 463 Pseudomonas aeruginosa are increasingly prevalent in China. This study aims to investigate how blaKPC-2 is acquired in ST463 P. aeruginosa during antimicrobial therapy. Methods: Two extensively drug-resistant P. aeruginosa strains, B1122 and U1121, were respectively isolated from blood and urine of a patient during carbapenem therapy. Whole-genome sequences were obtained, and minimum inhibitory concentrations (MICs) were determined. Plasmid transferability and stability were examined. Bacterial growth kinetics, biofilm formation, and virulence level was assessed. Results: U1121 and B1122 were only susceptible to amikacin and intermediately susceptible to colistin. They were isogenic ST463 P. aeruginosa strains and shared the same chromosome-encoded resistance genes, including blaAFM-1. This is the first report of chromosomal integration of blaAFM-1 in P. aeruginosa mediated by ISCR29. pU1121 and pB1122, which shared almost identical backbone, were the sole plasmids in U1121 and B1122, respectively, differing by an insertion region containing two copies of blaKPC-2 genes observed on pU1121. Sequence alignment revealed that pU1121 might evolve in vivo from pB1122 via IS26-mediated continuous genetic rearrangement in response to selective challenge from carbapenem. pU1121 was not self-transmissible and could be stably maintained in the host in the absence of antibiotic. Both U1121 and B1122 were hypervirulent, and no differences on virulence were recorded between them. However, U1121 exhibited significant impaired growth in comparison with B1122. Conclusion: ST463 P. aeruginosa can capture blaKPC-2 through horizontal transfer of insertion sequence under antibiotic selection pressure, which does decrease the fitness but does not impair the virulence of the ancestor
Nucleic Acid and Nanomaterial Synergistic Amplification Enables Dual Targets of Ultrasensitive Fluorescence Quantification to Improve the Efficacy of Clinical Tuberculosis Diagnosis
Interferon-γ (IFN-γ) release assays (IGRAs)
are constrained
by the limited diagnostic performance of a single indicator and the
excessive Mycobacterium tuberculosis (Mtb) antigen stimulation time. This study presents
a simultaneous, homogeneous, rapid, and ultrasensitive fluorescence
quantification strategy for IFN-γ and IFN-γ-induced protein
10 (IP-10). This method relies on the high-affinity binding of aptamers
to IFN-γ and IP-10, the enzyme-free catalytic hairpin assembly
reaction, and the heightened sensitivity of CdTe quantum dots to Ag+ and hairpin structure C-Ag+-C and carbon dots
to Hg2+ and hairpin structure T-Hg2+-T. Under
optimized conditions, the selectivity of IFN-γ and IP-10 was
excellent, with a linear range spanning from 1 to 100 ag/mL and low
limits of detection of 0.3 and 0.5 ag/mL, respectively. Clinical practicality
was confirmed through testing of 57 clinical samples. The dual-indicator
combination detection showed 92.8% specificity and 93.1% sensitivity,
with an area under the curve of 0.899, representing an improvement
over the single-indicator approach. The Mtb antigen
stimulation time was reduced to 8 h for 6/7 clinical samples. These
findings underscore the potential of our approach to enhance the efficiency
and performance of a tuberculosis (TB) clinical diagnosis
Efficacy of an autophagy-targeted DNA vaccine against avian leukosis virus subgroup J
Infection with the avian leukosis virus subgroup J (ALV-J) can lead to neoplastic disease in chickens, inflicting significant economic losses to the poultry industry. Recent reports have identified inhibitory effects of ALV-J on autophagy, a process involving in innate and adaptive immunity. Inspired by this connection between autophagy and immunity, we developed a novel DNA vaccine against ALV-J which includes co-administration of rapamycin to stimulate autophagy. To measure the efficacy of the developed prototype vaccine, five experimental groups of seven-day-old-chickens was immunized three times at three-week intervals respectively with vector, pVAX1-gp85, pVAX1-gp85-LC3, pVAX1-gp85 + rapamycin and pVAX1-gp85-LC3 + rapamycin through electroporation. We then tested their antibody titers, cytokine levels and cellular immune responses. The immunoprotective efficacy of the prototype vaccines against the challenge of the ALV-J GD1109 strain was also examined. The results showed that the combination of pVAX1-gp85-LC3 and rapamycin was able to induce the highest antibody titers, and enhance interleukin(IL)-2, IL-10 and interferon (IFN)-gamma expression, and the chickens immunized with the combination of pVAX1-gp85-LC3 and rapamycin showed the highest percentage of CD3+ CD8+ T lymphocytes. Based on our results, we suggest that stimulating autophagy can improve the efficacy of DNA vaccines and that our DNA vaccine shows the potential of being a candidate vaccine against ALV-J. This study provides a novel strategy for developing vaccines against ALV-J. (C) 2016 Elsevier Ltd. All rights reserved
Label-Free and Separation-Free Atomic Fluorescence Spectrometry-Based Bioassay: Sensitive Determination of Single-Strand DNA, Protein, and Double-Strand DNA
Based on selective
and sensitive determination of Hg<sup>2+</sup> released from mercury
complex by cold vapor generation (CVG) atomic
fluorescence spectrometry (AFS) using SnCl<sub>2</sub> as a reductant,
a novel label-free and separation-free strategy was proposed for DNA
and protein bioassay. To construct the DNA bioassay platform, an Hg<sup>2+</sup>-mediated molecular beacon (hairpin) without labeling but
possessing several thymine (T) bases at both ends was employed as
the probe. It is well-known that Hg<sup>2+</sup> could trigger the
formation of the hairpin structure through T–Hg<sup>2+</sup>–T connection. In the presence of a specific target, the hairpin
structure could be broken and the captured Hg<sup>2+</sup> was released.
Interestingly, it was found that SnCl<sub>2</sub> could selectively
reduce only free Hg<sup>2+</sup> to Hg<sup>0</sup> vapor in the presence
of T–Hg<sup>2+</sup>–T complex, which could be separated
from sample matrices for sensitive AFS detection. Three different
types of analyte, namely, single-strand DNA (ssDNA), protein, and
double-strand DNA (dsDNA), were investigated as the target analytes.
Under the optimized conditions, this bioassay provided high sensitivity
for ssDNA, protein, and dsDNA determination with the limits of detection
as low as 0.2, 0.08, and 0.3 nM and the linear dynamic ranges of 10–150,
5–175, and 1–250 nM, respectively. The analytical performance
for these analytes compares favorably with those by previously reported
methods, demonstrating the potential usefulness and versatility of
this new AFS-based bioassay. Moreover, the bioassay retains advantages
of simplicity, cost-effectiveness, and sensitivity compared to most
of the conventional methods