Nitrogen Fixation and Diazotrophic Community in Plastic-Eating Mealworms Tenebrio molitor L.

Mealworms, the larvae of a coleopteran insect Tenebrio molitor L., are capable of eating, living on, and degrading non-hydrolyzable vinyl plastics as sole diet. However, vinyl plastics are carbon-rich but nitrogen-deficient. It remains puzzling how plastic-eating mealworms overcome the nutritional obstacle of nitrogen limitation. Here, we provide the evidence for nitrogen fixation activity within plastic-eating mealworms. Acetylene reduction assays illustrate that the nitrogen-fixing activity ranges from 12.3 ± 0.7 to 32.9 ± 9.3 nmol ethylene·h-1·gut-1 and the corresponding fixed nitrogen equivalents of protein are estimated as 8.6 to 23.0 µg per day per mealworm. Nature nitrogen isotopic analyses of plastic-eating mealworms provide further evidence for the assimilation of fixed nitrogen as a new nitrogen source. Eliminating the gut microbial microbiota with antibiotics impairs the mealworm's ability to fix nitrogen from the atmosphere, indicating the contribution of gut microbiota to nitrogen fixation. By using the traditional culture-dependent technique, PCR and RT-PCR of nifH gene, nitrogen-fixing bacteria diversity within the gut was detected, and the genus Klebsiella was demonstrated to be an important nitrogen-fixing symbiont. These findings first build the relationship between plastic degradation (carbon metabolism) and nitrogen fixation (nitrogen metabolism) within mealworms. Combined with previously reported plastic-degrading capability and nitrogen-fixing activity, mealworms may be potential candidates for up-recycling of plastic waste to produce protein sources.

Starch/microcrystalline cellulose hybrid gels as gastric-floating drug delivery systems.

We report hybrid gels based on a high-amylose starch and microcrystalline cellulose with demonstrated properties for gastric-floating drug delivery purposes. The starch/cellulose gels were prepared by ionic liquid dissolution and regeneration, resulting in a continuous surface and a porous interior and a type-II crystalline structure of cellulose. These polysaccharide gels displayed satisfactory elasticity (0.88), recovery (0.26-0.36) and equilibrium swelling (1013-1369%). The hybrid gels were loaded with ranitidine hydrochloride as a model drug and subsequently, low-density starch/cellulose tablets were fabricated by vacuum-freeze-drying. In vitro tests in a simulated gastric fluid indicate that the 3:7 (wt./wt.) starch/cellulose system could maintain the buoyancy for up to 24 h with a release of 45.87% for the first 1 h and a sustained release for up to 10 h. Therefore, our results have demonstrated the excellent gastric-floating ability and sustainable drug release behavior of the starch/cellulose hybrid gels.

Effect of anti-solvents on the characteristics of regenerated cellulose from 1-ethyl-3-methylimidazolium acetate ionic liquid.

This work investigates the effect of different anti-solvents (water, ethanol, or both water and ethanol) on the characteristics of cellulose dissolved and then generated from 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]). Compared with original microcrystalline cellulose (MCC) granules, all regenerated celluloses showed a homogeneous, agglomerated macromorphology and had its crystalline structure transformed from original cellulose I to cellulose II. The regenerated cellulose using water (43.3%) had a higher degree of crystallinity than that using ethanol (13.5%), and a degree of crystallinity of 21.3% was obtained when an ethanol-water-ethanol treatment method was used. SAXS and FTIR results indicate that water as an anti-solvent could promote the rearrangement of cellulose molecular chains and the rebuilding of an ordered aggregated structure. Moreover, the regenerated cellulose with water showed better thermal stability than that of the samples regenerated using ethanol. Thus, our results suggest that the reconstitution of cellulose molecules during regeneration with various anti-solvents can affect the multiscale structures and properties of cellulose.

[Effects of Plastic Film Mulching and Nitrogen Fertilizer Application on CH4 Emissions from a Vegetable Field].

To investigate the effects of plastic film mulching and nitrogen fertilizer application on CH4 emissions from a vegetable field, static opaque and gas chromatography methods were applied, and in situ field observations of a chili-radish rotation system, from May 2014 to April 2016, were carried out in the Key Field Station for Monitoring of Eco-Environment of Purple Soil of the Ministry of Agriculture of China in the farm of Southwest University in Chongqing. Eight treatments were set up in the field experiment:control routine (no N application and no plastic film mulching) (NN0), control mulching (FN0), low N routine (NN1), low N mulching (FN1), conventional N routine (NN2), conventional N mulching (FN2), high N routine (NN3), and high N mulching (FN3). The characteristics and influencing factors of CH4 emissions and the changes of soil carbon and nitrogen composition from all treatments were studied. The results showed that there was no significant difference in the CH4 emissions from the vegetable fields between the mulching methods. From May 2014 to April 2016, the annual average cumulative absorption of CH4 in nitrogen-free, low-nitrogen, medium-nitrogen, and high-nitrogen vegetable fields under film-mulching cultivation was 28.96, 51.90, 43.43, and 34.41 mg·m-2, respectively. The average annual cumulative uptake of CH4 under conventional planting was 40.76, 63.56, 62.77, and 21.92 mg·m-2, respectively. Different nitrogen application gradients had no significant effect on CH4 emissions from vegetable fields. There was a significant positive correlation between CH4 uptake and soil temperature, and a significant negative correlation between CH4 and soil water content. Plastic film coverage accelerated the mineralization of soil carbon in the pepper season, but there was no significant effect in the radish season.

[Effects of Plastic Film Mulching and Nitrogen Fertilizer Application on N2O Emissions from a Vegetable Field].

To investigate the effects of plastic film mulching and nitrogen fertilizer application on N2O emissions from a chili-radish rotation system, field observations were conducted in situ from May 2014 to April 2016 in the Key Field Station for Monitoring of Eco-Environment of Purple Soil of the Ministry of Agriculture of China in the farm of Southwest University in Chongqing. Static opaque and gas chromatography was used to determine emissions. Eight treatments were set up in the field experiment:control routine (no N application and no plastic film mulching; NN0), control mulching (FN0), low N routine (NN1), low N mulching (FN1), conventional N routine (NN2), conventional N mulching (FN2), high N routine (NN3), and high N mulching (FN3). The characteristics and influencing factors of N2O emissions and the changes of soil carbon and nitrogen composition across all treatments were examined. The results demonstrated significant differences in N2O emissions from the vegetable fields between mulching and no mulching treatments. The mean N2O flux under no mulching was significantly greater than that of mulching during the chili growing season (P<0.05), but the opposite was true during the radish growing season (P<0.05). During the experimental period, the average annual cumulative N2O emissions from nitrogen-free, low-nitrogen, medium-nitrogen, and high-nitrogen vegetable plots under mulching treatment were 244.91, 730.49, 903.32, and 1865.45 mg·m-2, respectively; the average annual cumulative N2O emissions under no mulching treatment were 221.48, 840.33, 1256.50, and 1469.67 mg·m-2, respectively. The N2O emissions from vegetable plots with different N application gradients showed an increase in N2O emissions from vegetable plots as N application increased. By calculating the N2O emissions coefficient, it was determined that the N2O emissions coefficient was reduced to a certain extent under mulching treatment during the chili season, while there was no obvious trend in the radish season. From May 2014 to April 2015, the N2O emissions coefficients of low-nitrogen application under two mulching treatments were both the highest under the same mulching levels during the chili growing season, but they were both the highest in the high-nitrogen application under two mulching levels during the radish growing season. From May 2015 to April 2016, the highest N2O emissions coefficient was observed in the high-nitrogen application under two mulching treatments during the chili season; however, the lowest values were observed in the low-nitrogen application under two mulching treatments during the radish growing season. Such results may be related to the duration of plastic film mulching and the type of plant. The N2O fluxes were both significantly positively correlated to the content of soil N and soil temperature. Plastic film mulching can increase the soil N to a certain extent and can therefore can affect N2O emissions.

Tunable d-Limonene Permeability in Starch-Based Nanocomposite Films Reinforced by Cellulose Nanocrystals.

In order to control d-limonene permeability, cellulose nanocrystals (CNC) were used to regulate starch-based film multiscale structures. The effect of sphere-like cellulose nanocrystal (CS) and rod-like cellulose nanocrystal (CR) on starch molecular interaction, short-range molecular conformation, crystalline structure, and micro-ordered aggregated region structure were systematically discussed. CNC aspect ratio and content were proved to be independent variables to control d-limonene permeability via film-structure regulation. New hydrogen bonding formation and increased hydroxypropyl starch (HPS) relative crystallinity could be the reason for the lower d-limonene permeability compared with tortuous path model approximation. More hydrogen bonding formation, higher HPS relative crystallinity and larger size of micro-ordered aggregated region in CS0.5 and CR2 could explain the lower d-limonene permeability than CS2 and CR0.5, respectively. This study provided new insight for the control of the flavor release from starch-based films, which favored its application in biodegradable food packaging and flavor encapsulation.

Flexible bipolar nanofibrous membranes for improving gradient microstructure in tendon-to-bone healing.

Enthesis is a specialized tissue interface between the tendon and bone. Enthesis structure is very complex because of gradient changes in its composition and structure. There is currently no strategy to create a suitable environment and to regenerate the gradual-changing enthesis because of the modular complexities between two tissue types. Herein, a dual-layer organic/inorganic flexible bipolar fibrous membrane (BFM) was successfully fabricated by electrospinning to generate biomimetic non-mineralized fibrocartilage and mineralized fibrocartilage in tendon-to-bone integration of enthesis. The growth of the in situ apatite nanoparticle layer was induced on the nano hydroxyapatite-poly-l-lactic acid (nHA-PLLA) fibrous layer in simulated body solution, and the poly-l-lactic acid (PLLA) fibrous layer retained its original properties to induce tendon regeneration. The in vivo results showed that BFM significantly increased the area of glycosaminoglycan staining at the tendon-bone interface and improved collagen organization when compared to the simplex fibrous membrane (SFM) of PLLA. Implanting the bipolar membrane also induced bone formation and fibrillogenesis as assessed by micro-CT and histological analysis. Biomechanical testing showed that the BFM group had a greater ultimate load-to-failure and stiffness than the SFM group at 12weeks after surgery. Therefore, this flexible bipolar nanofibrous membrane improves the healing and regeneration process of the enthesis in rotator cuff repair. STATEMENT OF SIGNIFICANCE: In this study, we generated a biomimetic dual-layer organic/inorganic flexible bipolar fibrous membrane by sequential electrospinning and in situ biomineralization, producing integrated bipolar fibrous membranes of PLLA fibrous membrane as the upper layer and nHA-PLLA fibrous membrane as the lower layer to mimic non-mineralized fibrocartilage and mineralized fibrocartilage in tendon-to-bone integration of enthesis. Flexible bipolar nanofibrous membranes could be easily fabricated with gradient microstructure for enthesis regeneration in rotator cuff tears.

Colorimetric assay for protein detection based on "nano-pumpkin" induced aggregation of peptide-decorated gold nanoparticles.

Small peptide can be used as an effective biological recognition element and provide an alternative tool for protein detection. However, the development of peptide-based detecting strategy still remains elusive due to the difficulty of signal transduction. Herein, we report a peptide-based colorimetric strategy for the detection of disease biomarker by using vascular endothelial growth factor receptor 1 (Flt-1) as an example. In this strategy, N-terminal aromatic residue-containing peptide modified gold nanoparticles (GNPs) can form bulky aggregate by the introduction of cucurbit[8]uril (CB[8]) that can selectively accommodate two N-terminal aromatic residue of peptides simultaneously regardless of their sequences. However, in the presence of Flt-1, the peptide can specifically bind to the protein molecule and the N-terminal aromatic residue will be occupied, resulting in little aggregation of GNPs. By taking advantage of the highly affinitive peptide and efficiency cross-linking effect of CB[8] to GNPs, colorimetric assay for protein detection can be achieved with a detection limit of 0.2 nM, which is comparable with traditional methods. The feasibility of our method has also been demonstrated in spiked serum sample, indicating potential application in the future.

Application of a new combined model including radiological indicators to predict difficult airway in patients undergoing surgery for cervical spondylosis.

BACKGROUND: Airway management is crucial in clinical anesthesia. Many complications associated with airway management result from unexpected difficult airway, but predicting a difficult airway is a major challenge. We investigated the efficacy of a new combined model including radiological indicators to predict difficult airway in patients undergoing surgery for cervical spondylosis, a population with a high incidence of difficult airway. METHODS: We randomly enrolled 303 patients scheduled for elective surgery for cervical spondylosis at Peking University Third Hospital between August 2012 and March 2013. Preoperatively, patients were evaluated for difficult airway according to a clinical index and parameters on lateral cervical radiographs and magnetic resonance images. Difficult airway was defined as Cormack-Lehane grades III-IV. Logistic regression was used to identify a combined (clinical and radiological) model for difficult airway. A receiver operating characteristic (ROC) curve was used to describe the effectiveness of prediction. RESULTS: We identified three clinical predictive factors using the ROC curve: mouth opening, sternomental distance, and neck mobility. We created a clinical model using three factors: gender, age, and mouth opening, with odds ratios (OR) of 0.370, 1.034, and 0.358, respectively. Using the clinical and radiological parameters, we formulated a combined model with five risk factors: gender, mouth opening, atlanto-occipital gap, the angle from the second to sixth cervical vertebraes in the neutral position, and the angle difference of d (the angle between the laryngeal axis and the epiglottic axis) from the neutral position to extension (OR: 0.107, 0.355, 0.846, 1.057, and 0.952, respectively). The sensitivity and specificity of the combined model were 80.0% and 65.7%, respectively, and the ROC curve confirmed that the combined model was better than any single clinical predictor and the clinical model. CONCLUSION: The efficacy of the combined model including both clinical and radiological indicators was better than any single clinical predictor or the clinical model in patients undergoing elective surgery for cervical spondylosis.

The properties of antimicrobial films derived from poly(lactic acid)/starch/chitosan blended matrix.

An antimicrobial material with a slow release property was developed based on poly(lactic acid)/starch/chitosan blends, in which chitosan acted as an antimicrobial agent while PLA and starch together were used as a slow-releasing device. An increase in the starch content drastically improved the hydrophilicity of the blends, which was favorable for the diffusion of the embedded chitosan. Moreover, the release of chitosan was observed to occur in two stages, with a very fast release stage initially and a slow but durable release stage as the latter. These two stages exhibited the effectiveness and long residual action of antimicrobial property of the blends respectively, demonstrating the suitability to be used for foods with high water activity, such as fresh meat. The tensile and thermal properties further verified the promising use of the blend material in packaging.

Cosmetic outcome and surgical site infection rates of antibacterial absorbable (Polyglactin 910) suture compared to Chinese silk suture in breast cancer surgery: a randomized pilot research.

BACKGROUND: The primary objective of this multicenter post-market study was to compare the cosmetic outcome of triclosan-coated VICRYL Plus sutures with Chinese silk sutures for skin closure of modified radical mastectomy. A secondary objective was to assess the incidence of surgical site infection (SSI). METHODS: Patients undergoing modified radical mastectomy were randomly assigned to coated VICRYL Plus antibacterial (Polyglactin 910) suture or Chinese silk suture. Cosmetic outcomes were evaluated postoperatively at days 12 (± 2) and 30 (± 5), and the evidence of SSI was assessed at days 3, 5, 7, 12 (± 2), 30 (± 5), and 90 (± 7). Cosmetic outcomes were independently assessed via visual analogue scale (VAS) score evaluations of blinded incision photographs (primary endpoint) and surgeon-assessed modified Hollander Scale (mHCS) scores (secondary endpoint). SSI assessments used both CDC criteria and ASEPSIS scores. RESULTS: Six Chinese hospitals randomized 101 women undergoing modified radical mastectomy to closure with coated VICRYL Plus suture (n = 51) or Chinese silk suture (n = 50). Mean VAS cosmetic outcome scores for antibacterial suture (67.2) were better than for Chinese silk (45.4) at day 30 (P < 0.0001)). Mean mHCS cosmetic outcome total scores, were also higher for antibacterial suture (5.7) than for Chinese silk (5.0) at day 30 (P = 0.002). CONCLUSIONS: Patients using coated VICRYL Plus suture had significantly better cosmetic outcomes than those with Chinese silk sutures. Patients using coated VICRYL Plus suture had a lower SSI incidence compared to the Chinese silk sutures, although the difference did not reach statistical significance.

Intensive statin therapy: a favorable adjunct to the improvement of small-diameter vascular grafts.

To assess the effect of intensive statins therapy on the outcome of small-diameter vascular prosthesis, we investigated whether atorvastatin treatment (30 mg/d) could accelerate the re-endothelialization process and improve the patency rate in a canine infrarenal abdominal aorta-expanded polytetrafluoroethylene (ePTFE) bypass model. Furthermore, we also evaluated the effect of atorvastatin on the migratory and adherent capacity of circulating endothelial progenitor cells (EPCs) in vitro. Improved patency was confirmed by Doppler sonography and arteriography. Histological and scanning electron microscopy illustrated enhanced re-endothelialization process. Treatment with atorvastatin enhanced the circulating pool of EPCs with fortified migratory and adherent capacity. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed that atorvastatin treatment increased endothelial nitric oxide synthase (eNOS) and kinase insert domain receptor (KDR) messenger RNA (mRNA) expression in cultured EPCs and neointima. In conclusion, intensive statin therapy could be considered a favorable option to improve small-diameter vascular graft patency.