The low reproducibility is the most critical obstacle to the wide commercial application of laser-induced breakdown spectroscopy (LIBS). In this work, to improve the sample-to-sample reproducibility ...of LIBS real-time analysis of coal calorific value, we applied the acoustic signal generated by the laser ablation as the reference signal for normalization. First, the correlation between acoustic signal and spectral signal was analyzed and the results showed that the spectral signal from coal pellet samples with 35-ton compaction pressure had a strong correlation with acoustic signal. Second, the influences of shot-to-shot spectral intensities with different normalization methods were analyzed, including total area normalization, channel normalization, background normalization and acoustic normalization. Finally, different normalization models for calorific value were established using the support vector regression (SVR). With the acoustic normalization method, the relative standard deviation (RSD) of shot-to-shot intensities of spectral lines of C (I) 193.1 nm, C (I) 247.8 nm, H (I) 656.3 nm and N (I) 868.1 nm were significantly reduced from 10.16, 6.53, 3.79, 5.21% to 7.01, 4.40, 2.81, 3.54%, respectively. Moreover, compared with model without normalization, the average RSD of sample-to-sample measurements of validation samples based on acoustic normalization method was reduced from 6.25% to 4.16%, and the average relative error (ARE) was reduced from 4.66% to 3.28%. The results demonstrated that the acoustic normalization method can effectively reduce the fluctuations of the shot-to-shot spectral intensities and was an effective method to improve the reproducibility and accuracy of measurement of coal calorific value in LIBS.
A central resistance mechanism in solid tumors is the maintenance of epithelial junctions between malignant cells that prevent drug penetration into the tumor. Human adenoviruses (Ads) have evolved ...mechanisms to breach epithelial barriers. For example, during Ad serotype 3 (Ad3) infection of epithelial tumor cells, massive amounts of subviral penton-dodecahedral particles (PtDd) are produced and released from infected cells to trigger the transient opening of epithelial junctions, thus facilitating lateral virus spread. We show here that an Ad3 mutant that is disabled for PtDd production is significantly less effective in killing of epithelial human xenograft tumors than the wild-type Ad3 virus. Intratumoral spread and therapeutic effect of the Ad3 mutant was enhanced by co-administration of a small recombinant protein (JO; produced in Escherichia coli) that incorporated the minimal junction opening domains of PtDd. We then demonstrated that co-administration of JO with replication-competent Ads that do not produce PtDd (Ad5, Ad35) resulted in greater attenuation of tumor growth than virus injection alone. Furthermore, we genetically modified a conditionally replicating Ad5-based oncolytic Ad (Ad5Δ24) to express a secreted form of JO upon replication in tumor cells. The JO-expressing virus had a significantly greater antitumor effect than the unmodified AdΔ24 version. Our findings indicate that epithelial junctions limit the efficacy of oncolytic Ads and that this problem can be address by co-injection or expression of JO. JO has also the potential for improving cancer therapy with other types of oncolytic viruses.
A novel method for the determination of Vanadium (V), Iron (Fe), and Nickel (Ni) in petroleum coke by laser-induced breakdown spectroscopy (LIBS) was proposed. Compared with the current common ...methods for determining elements in petroleum coke, which require a variety of reagents and a longer operation time, the LIBS method has the advantages of simple sample pre-treatment, faster measurement speed, less pollution of the measuring environment, and no reagents consumption. After feature selection of the wavelengths corresponding to V, Fe, and Ni in the LIBS spectrum of petroleum coke, the element contents of the test set were predicted after SVR modelling for the three elements in the training set. The results of root-mean-square error of predictions (RMSEP) for V, Fe and Ni were 36.4 mg/kg, 36.04 mg/kg and 14.94 mg/kg. The RMSEP of V and Ni were close to the reproducibility (accuracy) of element measurements (32 mg/kg and 14 mg/kg) using the wavelength dispersive X-ray fluorescence spectroscopy (WD-XFS) method in ASTM D6376–10 standard. This work demonstrated that this LIBS-based petroleum coke element quantitative analysis method, which was used for the first time, can be applied to the rapid detection of the petroleum coke industry.
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•LIBS quick analysis of petroleum coke, simple design with low cost.•RMSE values of SVM modelling results were sorted by removing independent variables, and feature selection was carried out.•The first work in applying the LIBS to detections of petroleum coke.•A promising application prospect as rapid in-situ detections of petroleum coke.
A hybrid feature selection method combining with wavelet transform (WT) was proposed to analyze the heat value of coal using laser-induced breakdown spectroscopy (LIBS). The hybrid feature selection ...method consisted of distance correlation (DC) method and recursive feature elimination with cross-validation (RFECV) method, which combined the advantages of DC-based filter method and RFECV-based wrapper method. First, WT method was used to filter noise signal from LIBS spectra of coal samples, and the de-noised wavelet coefficients were obtained. Second, the de-noised wavelet coefficients were further eliminated by the hybrid feature selection method. Finally, the retained wavelet coefficients were used directly as input variables to establish a prediction model for heat value determination of coal. 28 powdery coal samples were used in this experiment, of which 21 were calibration set and 7 were validation set. The effectiveness of the hybrid model was studied. Compared with several other models, the proposed hybrid model showed the greatest improvement in predictive accuracy and precision, and the computing time has been greatly reduced. The experimental results demonstrated that the hybrid model can effectively reduce the calculation time and improve the performance of the model.
Highlights • Nampt is overexpressed in pancreatic cancer. • Inhibition of Nampt impaired pancreatic cancer growth in vitro and in vivo. • The expression of Nampt is regulated by miR-206 in pancreatic ...cancer. • Inhibition of Nampt enhanced the antitumor activity of gemcitabine in PDAC.
Human adenovirus serotypes Ad3, Ad7, Ad11, and Ad14 use the epithelial junction protein desmoglein 2 (DSG2) as a receptor for infection. During Ad infection, the fiber and penton base capsid proteins ...are produced in vast excess and form hetero-oligomers, called pentons. It has been shown for Ad3 that pentons self-assemble into penton-dodecahedra (PtDd). Our previous studies with recombinant purified Ad3 PtDd (produced in insect cells) showed that PtDd bind to DSG2 and trigger intracellular signaling resulting in the transient opening of junctions between epithelial cells. So far, a definitive proof for a function of Ad3 PtDd in the viral life cycle is elusive. Based on the recently published 3D structure of recombinant Ad3 PtDd, we generated a penton base mutant Ad3 vector (mu-Ad3GFP). mu-Ad3GFP is identical to its wild-type counterpart (wt-Ad3GFP) in the efficiency of progeny virus production; however, it is disabled in the production of PtDd. For infection studies we used polarized epithelial cancer cells or cell spheroids. We showed that in wt-Ad3GFP infected cultures, PtDd were released from cells before viral cytolysis and triggered the restructuring of epithelial junctions. This in turn facilitated lateral viral spread of de novo produced virions. These events were nearly absent in mu-Ad3GFP infected cultures. Our in vitro findings were consolidated in mice carrying xenograft tumors derived from human epithelial cancer cells. Furthermore, we provide first evidence that PtDd are also formed by another DSG2-interacting Ad serotype, the newly emerged, highly pathogenic Ad14 strain (Ad14p1). The central finding of this study is that a subgroup of Ads has evolved to generate PtDd as a strategy to achieve penetration into and dissemination in epithelial tissues. Our findings are relevant for basic and applied virology, specifically for cancer virotherapy.
The gene transduction efficiency of adenovirus to hematopoietic cells, especially T lymphocytes, is needed to be improved. The purpose of this study is to improve the transduction efficiency of T ...lymphocytes by using fiber-modified human adenovirus 5 (HAdV-5) vectors.
Four fiber-modified human adenovirus 5 (HAdV-5) vectors were investigated to transduce hematopoietic cells. F35-EG or F11p-EG were HAdV-35 or HAdV-11p fiber pseudotyped HAdV-5, and HR-EG or CR-EG vectors were generated by incorporating RGD motif to the HI loop or to the C-terminus of F11p-EG fiber. All vectors could transduce more than 90% of K562 or Jurkat cells at an multiplicity of infection (MOI) of 500 viral particle per cell (vp/cell). All vectors except HR-EG could transduce nearly 90% cord blood CD34+ cells or 80% primary human T cells at the MOI of 1000, and F11p-EG showed slight superiority to F35-EG and CR-EG. Adenoviral vectors transduced CD4+ T cells a little more efficiently than they did to CD8+ T cells. These vectors showed no cytotoxicity at an MOI as high as 1000 vp/cell because the infected and uninfected T cells retained the same CD4/CD8 ratio and cell growth rate.
HAdV-11p fiber pseudotyped HAdV-5 could effectively transduce human T cells when human EF1a promoter was used to control the expression of transgene, suggesting its possible application in T cell immunocellular therapy.
Highlights • Serum neutralizing antibodies to Ad5 and Ad41 in adults and children were titrated. • Prevalence of NAb in children was associated with age and sanitary conditions. • NAb titer ...distribution pattern was very different between Ad5 an Ad41. • Ad41 vectored vaccine candidates might have a bright future.
•Gibson gene assembly method was used to generate infectious clone of fowl adenovirus 4 (FAdV-4).•Purification and one-step growth curve of the rescued FAdV-4 was studied.•DNA assembly simplified the ...construction of infectious clone of adenovirus when compared with traditional methods.
Plasmid bearing adenovirus genome is generally constructed with the method of homologous recombination in E. coli BJ5183 strain. Here, we utilized Gibson gene assembly technique to generate infectious clone of fowl adenovirus 4 (FAdV-4). Primers flanked with partial inverted terminal repeat (ITR) sequence of FAdV-4 were synthesized to amplify a plasmid backbone containing kanamycin-resistant gene and pBR322 origin (KAN-ORI). DNA assembly was carried out by combining the KAN-ORI fragment, virus genomic DNA and DNA assembly master mix. E. coli competent cells were transformed with the assembled product, and plasmids (pKFAV4) were extracted and confirmed to contain viral genome by restriction analysis and sequencing. Virus was successfully rescued from linear pKFAV4-transfected chicken LMH cells. This approach was further verified in cloning of human adenovirus 5 genome. Our results indicated that DNA assembly technique simplified the construction of infectious clone of adenovirus, suggesting its possible application in virus traditional or reverse genetics.
This paper presents a theoretical methodology for predicting the fracture pattern of a thin brittle plate subjected to normal impact loads. The approach is based on the principle of minimum external ...work, which is obtained directly from the principle of least action. Global scaling laws of the number of radial cracks, the maximum radial crack speed, and the critical impact velocity when radial cracks appear are established. It is found that the fracture pattern is controlled by two dimensionless parameters: one is the ratio of the striking velocity to the longitudinal wave speed, and the other is the ratio of the surface energy to Young's modulus (bridging the material length to the macroscopic geometrical size). The physical meaning of this material length is further investigated by assuming that a body's internal energy should simultaneously consider the surface and the volumetric parts. On the one hand, this length represents the competition of the internal energy between the surface and the volumetric parts. On the other hand, this material length is consistent with the distance of neighbor atoms in equilibrium.
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