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Summary Smoking is mainly sustained by nicotine dependence (ND), which varies across ethnic groups principally due to genetic as well as environmental factors. The Fagerström Test for Nicotine Dependence (FTND) and biomarkers of tobacco exposure are two important approaches to assess ND. However, the relationship between ND and FTND of Chinese smokers has not been studied. The aim of this study was to assess the relationship between FTND scores and nicotine, cotinine, 3′-hydroxycotinine (3HC) and nicotine metabolite ratio (NMR, the concentration ratio of 3HC to cotinine) in Chinese smokers. FTND was carried out and general characteristics were collected using a self-administered smoking questionnaire with 289 smokers. Nicotine, cotinine and 3HC in urine were simultaneously determined by liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS). The concentrations of nicotine, cotinine and 3HC in the urine of smokers with a high FTND score were higher than in the urine of those with a low FTND score. There were significant correlations between urinary biomarker and FTND scores. Except for FTND item 2 (difficulty to refrain), the other items showed significant associations with the urinary biomarkers. No relationship was found between the nicotine metabolite ratio (NMR, 3′-hydroxycotinine/cotinine) and FTND scores or general characteristics of the participants. In conclusion, biomarkers of tobacco exposure levels are significantly associated with FTND scores. However, FTND Item 2 and NMR were not found to be associated with nicotine dependence in Chinese smokers.

Additional file 3: Supplementary Figure 3. The regulation of differential expressed mRNAs, miRNAs, circRNAs and lncRNAs.

Nisin, a 34-amino acid polypeptide produced by certain Lactococcus lactis strains, is a bacteriocin used as a food preservative, and it is the only bacteriocin that has received FDA approval for use in purified form. Nisin is known to exert a high antibacterial activity against Gram-positive bacteria, however, is rather ineffective towards Gram-negative bacteria. The latter has been shown to be due to the outer membrane of these bacteria, which is impermeable to nisin and thus prevents it from reaching its target, lipid II, in the inner membrane. In recent years, nisin has been considered as an alternative to the classical antibiotics used to treat infections, especially caused by multi-drug resistant bacteria, and nisin has even been shown to excert an anti-cancer effects. One challenge that may conflict with its more broad application, is that nisin is quite expensive to produce; costly substrates are needed, production yields are low and the purification process is costly. Genetic engineering can be used to improve the nisin production, however, genetically engineered microorganisms (GMO’s) are generally not allowed in foods and production based on recombinant microorganisms is far from easy due to regulation. Therefore, isolation of natural, non-engineered strains that produce nisin with high yield, and development of new low-cost media is crucial if efficient industrial production of nisin is to be established. Furthermore, finding natural ways to enhance the antibacterial action of nisin against Gram-negative bacteria, such as food-borne Escherichia coli, can expand its application in food preservation.Like other lactic acid bacteria, L. lactis relies on glycolysis as its main source for generating the ATP needed for growth. The major fermentation end product, lactic acid, gradually accumulates during growth, and eventually causes growth arrest, even in pH-controlled fermentations. This is a challenge when producing nisin, as its production is biomass-dependent. In chapter 2, we describe the nisin-producing L. lactis strain Ge001, which was obtained after transferring the nisin gene cluster from L. lactis ATCC 11454, by conjugation, into the natural mutant L. lactis RD1M5, which has a low lactate dehydrogenase activity. The ability of Ge001 to produce nisin using dairy waste as the fermentation substrate was assessed. To accommodate redox cofactor regeneration, respiration conditions were used, and to alleviate oxidative stress and to reduce adsorption of nisin onto the producing cells, we found it to be beneficial to add 1 mM Mn2+ and 100 mM Ca2+, respectively. A high titer of 12084 IU/mL nisin was attained, which is comparable to the highest titers reported using expensive, rich media.Nisin-producing L. lactis strains can protect themselves against nisin through their immunity system, which is comprised of the lipoprotein NisI and the ABC transporter NisFEG. Despite the effectiveness of these immunity mechanisms, producing strains are not fully recalcitrant towards nisin, and nisin resistance thus is another bottleneck in nisin production. In chapter 3, it is described how adaptation of the nisin producer ATCC11454 to the cationic disinfectant chlorhexidine can lead to enhanced nisin production. The chlorhexidine resistant strain AT0606 had doubled its resistance to nisin, and produced three times more free nisin, when cultured in shake flasks. Subsequently, we explored the potential of using AT0606 for cost-efficient production of nisin, and were able to attain a high titer of 13181 IU/mL using a fermentation substrate based on molasses and a by-product from whey protein hydrolysate production.Foodborne and pathogenic E. coli strains pose a serious public health threat worldwide, and measures to control the growth of these harmful pathogens in foods are urgently needed. As mentioned above, nisin has difficulties penetrating the outer membrane of Gram-negative bacteria. Phytic acid (PA) is a natural plant antioxidant that potentially can destabilize the outer membrane of E. coli. In chapter 4, we study the antibacterial effect of nisin and PA cocktails against pathogenic E. coli O157:H7. It was found that nisin and PA, when combined, had a stronger bactericidal effect, and that the two compounds acted in a synergistic manner, both in the planktonic and the biofilm state, which was demonstrated by live/dead staining and plate counting. Electron scanning microscopy studies revealed that the nisin plus PA treatment had a severe effect on E. coli O157:H7, which after treatment appeared deflated with large invaginations in the cell envelope. The effect of nisin plus PA against E. coli O157:H7 was furthermore assessed on cold-stored beef, where the same synergistic effect was observed.Summing up, in this thesis, several important limitations of nisin have been addressed. We have demonstrated that it is feasible to greatly enhance the nisin production capacity of L. lactis by using natural approaches such as classical mutagenesis, natural conjugation and adaptive laboratory evolution. Two low cost media were explored, both of which were found to support excellent nisin production. Finally a major limitation of nisin was overcome; its low efficiency towards Gram-negative bacteria, where we found that nisin, when used in combination with PA, efficiently could eradicate a dangerous foodborne pathogen on cold stored beef.

Additional file 2: Table S2. Akaike information criterion for the prognostic signature.

Additional file 6: Supplementary Figure 6. The differential expressed mRNAs, top GO annotation and KEGG analysis. a. The volcanic map of differential expressed mRNAs. b. The top GO annotation of differential expressed mRNAs. c. The KEGG analysis of differential expressed mRNAs.

Additional file 1: Supplementary Figure 1. The transcriptome assembly quality control. a, The base quality of sequence. b, The pie chart for Rfam sequence category. c, the Biological Replicate quality control. d, The length distribution of counts of total sRNAs in this study.

Additional file 1: TableS1. PRISMA Network Meta-analysis Checklist. TableS2. Strategy of this meta-analysis. TableS3. Head-to-head comparisons of cesarean delivery rate. Table S4. Head-to-head comparisons oftime from intervention-to-birth. TableS5. Head-to-head comparisons of achieving vaginal delivery within 24 hours.Table S6. Head-to-head comparisonsof Bishop score increment. Table S7. Head-to-head comparisons of uterine hyperstimulation with fetal heart ratechanges. Table S8. Head-to-headcomparisons of oxytocin augmentation. TableS9. Head-to-head comparisons of instrumental delivery. Table S10. Head-to-head comparisons of meconium-stained amnioticfluid. Table S11. Head-to-headcomparisons of chorioamnionitis. TableS12. Head-to-head comparisons of postpartum hemorrhage. Table S13. Head-to-head comparisons ofApgar score

Additional file 4: Supplementary Figure 4. The construction of regulatory networks contains lncRNA, circRNA, miRNA and mRNA in peanut response to root -knot nematode.

With the global trend to establish smart distributed-generation grids, the level of AC-voltage harmonics is significantly increasing due to power electronic converters interfacing renewable energy sources with the grid. Such harmonics will not only degrade the power quality and increase the losses in the electricity grids but will also have a severe impact on oil impregnated paper (OIP) in power transformer bushings. While much attention has been given to investigate the deterioration of OIP under thermal and electrical stresses, the impact of voltage harmonics on the OIP structure is still uncertain and calls for more investigations. Therefore, this paper is aimed at investigating the variations of the multilevel structure of an OIP aged under high levels of AC-voltage harmonics. In this context, degree of polymerization of the aged OIP is measured to reveal the changes of OIP secondary structure. Also, X-ray diffraction, deuteration treatment and Fourier transform infra-red spectroscopy are conducted to analyze the changes of the OIP aggregate structure during the aging process. Further experiments are performed to investigate the variation of the microscopic appearance, thermal behavior and dielectric properties, including scanning electronic microscopy, thermal gravity analysis, differential scanning calorimetry and frequency domain spectroscopy. This investigation on the variation of the multilevel structure of aged OIP not only promotes further understanding to the aging behavior and mechanism of OIP under AC-voltage harmonics, but also proposes crystallinity and accessibility as two new effective aging indicators for the OIP structure.