Microscopic Morphological Changes Research Articles

Mobility control capability of a modified chitosan hyperbranched polymer in porous media

AbstractThe residual resistance factor (RRF) is an important parameter expressing the mobility control capability of the polymer, and it is related to the polymer molecular structure. This study investigated the ability of three polymers with different molecular structures to establish RRF in a one‐dimensional sand pack model at different permeabilities. In addition, the static adsorption capacity of the three polymers on the rock surface was investigated, and the mechanism of the polymer retention in porous media was explored by changing the wettability of the rock surface. Furthermore, the microscopic morphological changes of the polymers before and after passing through the porous media were observed by environmental scanning electron microscopy. Finally, nuclear magnetic resonance core flooding experiments were used to investigate the oil displacement characteristics of the three polymers in the core. T Results show that the ability of the three polymers to establish RRF gradually decreases with the increase in permeability. Still, the modified chitosan hyperbranched polymer (HPDACS) has the best ability to establish RRF in porous media with the largest static adsorption equilibrium amount of 1249 μg/g. Mechanical capture is the dominant mechanism for HPDACS to establish retention in porous media. In addition, HPDACS has a better ability to enhance recovery. It can improve oil recovery by 20.43%, which is higher than that by dendritic polymer HPDA at 16.34% and partially hydrolyzed polyacrylamide at 10.07%. HPDACS can establish a larger resistance in the macropores of the core. Thus, the remaining oil is better driven in the medium and small pores. This finding indicates that HPDACS has excellent potential for oil displacement.

Mechanical and micro-structural damage mechanisms of coal samples treated with dry–wet cycles

The construction of mine goafs as an underground reservoir to store and utilise mine water can effectively alleviate the contradiction between coal and water in the arid mining areas in western China. Understanding the effects of water on the mechanical properties and micro-structure of coal is essential for the stability design of coal pillar dams subjected to repeated water erosion. In this study, ultrasonic, X-ray diffraction, scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), and uniaxial compression tests were conducted on coal samples with zero to five dry–wet cycles to investigate the changes in water absorption characteristics, pore structure, microscopic morphology, and mechanical properties as the number of dry–wet cycles, n, increased. Moreover, the connection of the pore structure and microscopic morphology with the mechanical damage was established. The results showed that the peak stress and elastic modulus were negative exponential functions of n. As n increased, the moisture content saturation and homogeneity of the coal sample increased, the number of pores increased, and tiny pores within the coal converted to medium-to-large pores. Further, the peak stress had a good negative linear fit to the porosity and internal damage defined by the integrated area of the T2 curve. According to the SEM test results, the coal underwent five stages during a dry–wet cycle: uniform and dense original structure, particle aggregation, pore development, fracture sprouting, and overall structural fragmentation, with a gradual decrease in structural integrity. The damage variable, D, was defined by the fractal dimension, F, of the SEM images, enabling the quantitative characterisation of the coal microscopic damage during the dry–wet cycle; moreover, D/F was an exponential function of n. Finally, the damage mechanism of coal samples was interpreted from both macroscopic (i.e. NMR) and microscopic (i.e. SEM) perspectives, and they showed good agreement. Our results could provide a reference for the long-term stability assessment and design of coal pillar dams.

Reliability improvement of gas discharge tube by suppressing the formation of short-circuit pathways

After cumulative discharge of gas discharge tube (GDT), it is easy to form a short circuit pathway between the two electrodes, which increases the failure risk and causes severe influences on the protected object. To reduce the failure risk of GDT and improve cumulative discharge times before failure, this work aims to suppress the formation of two short-circuit pathways by optimizing the tube wall structure, the electrode materials and the electrode structure. A total of five improved GDT samples are designed by focusing on the insulation resistance change that occurs after the improvement; then, by combining these designs with the microscopic morphology changes inside the cavity and the differences in deposition composition, the reasons for the differences in the GDT failure risk are also analyzed. The experimental results show that compared with GDT of traditional structure and material, the method of adding grooves at both ends of the tube wall can effectively block the deposition pathway of the tube wall, and the cumulative discharge time before device failure is increased by 149%. On this basis, when the iron-nickel electrode is replaced with a tungsten-copper electrode, the difference in the electrode’s surface splash characteristics further extends the discharge time before failure by 183%. In addition, when compared with the traditional electrode structure, the method of adding an annular structure at the electrode edge to block the splashing pathway for the particles on the electrode surface shows no positive effect, and the cumulative discharge time before the failure of the two structures is reduced by 22.8% and 49.7%, respectively. Among these improved structures, the samples with grooves at both ends of the tube wall and tungsten-copper as their electrode material have the lowest failure risk.

Application of Mesoscale Simulation to Explore the pH Response of Eudragit S100 Used as the Novel Colon-Targeted Powder of Pulsatilla Saponin D

As a pH-sensitive nanomaterial, Eudragit S100 has good colon targeting. However, little research has been carried out on its mesoscopic scale. In this paper, the self-assembly behavior of Pulsatilla saponins D (PSD) and Eudragit S100, as well as the loading and release mechanism of PSD, was investigated via computer simulations. The effects of the self-assembly characteristics of PSD and Eudragit S100 in the dry powder state on the drug-carrier ratio were explored by the coarse-grained molecular dynamics (CGMD) method. According to the pH-responsive feature of Eudragit S100, the drug protection under gastric pH conditions and release in colonic pH conditions were simulated through the dissipative particle dynamics (DPD) method, which has provided insights into the microscopic morphological changes in the pH-sensitive drug delivery systems.

Study on shear performance of cotton straw fiber reinforced mud soil under freeze-thaw cycle

To explore the shear properties in cotton straw fiber-reinforced mud soil under freeze-thaw(F-T) cycles, direct shear tests are carried out on soil samples after different F-T times to obtain the influence of fiber content and F-T times to the shear strength of cotton straw fiber-reinforced soil. Then combined with scanning electron microscopy(SEM) to observe the microstructure of fiber and reinforced soil. Results indicate that the shear strength and cohesion of mud soil can be significantly improved by the addition of cotton straw fibers compared with plain soil, and the shear strength and cohesion of reinforced soil are higher than the plain soil during the same F-T times. Among three fiber contents of 0%, 0.2% and 0.4%, the shear strength and cohesion of 0.2% fiber-reinforced soil are higher than those of plain soil and 0.4% reinforced soil. After F-T cycles, the cohesion of soil decreases, among which the decrease is larger for 1 and 3 F-T times, and then the decrease of cohesion will be slowed down gradually, and when the number of F-T times reaches 10, the cohesion becomes stable. The internal friction angle for reinforced soil is higher than the plain soil, and it decreases first, then rises and finally decreases under the effect of F-T cycles, but in general, the changes are not large. The SEM observation shows that the microscopic morphological changes of the fibers themselves are small under the influence of F-T cycles, but the reinforced soil structure is destroyed, the pores and cracks become more, by which the connection between the fibers and soil particles decreases, resulting in a decline in the soil’s shear strength.

Preparation of Antibiotic-Loaded Copper-Doped Hydroxyapatite Microspheres and Evaluation of Their Antibacterial and Osteogenic Effect

To explore the preparation method of copper (Cu)-doped hydroxyapatite (HA) microspheres loaded with vancomycin (Van), and evaluate their antibacterial and osteogenic effects in vitro. The Cu doped HA microspheres (Cu-HA) with molar doping ratios of 1%, 5%, 10%, and 20% were prepared by hydrothermal synthesis. The microscopic morphology changes were observe with scanning electron microscope. X-ray diffractometer (XRD) was used to study the phase composition and analyze the crystallinity of the sample. Cu-HA with a molar doping ratio of 10% was selected for analysis of the elemental composition of the sample with energy dispersive X-ray spectroscopy (EDS), and was then coated with polydopamine (PDA) as the medium to prepare Cu-HA-PDA. XRD and Fourier infrared spectrometer were used to examine the coating effect of the sample. Van was load on Cu-HA-PDA to prepare Cu-HA-PDA-Van. HA, Cu-HA, HA-PDA, and Cu-HA-PDA-Van were added to α medium at 10 mg/mL to prepare different groups of extract solutions.The main components of the extract solutions were examined, and the Van concentration was checked. We examined the toxic effect of material extract solutions on osteogenic precursor cells and the proliferation and differentiation of bone marrow mesenchymal stem cells, and checked the expression of osteocalcin ( OCN), runt-related transcription factor 2 ( RUNX-2), and alkaline phosphatase ( ALP), the osteogenic related genes. Sterilized HA, Cu-HA, HA-PDA, Cu-HA-PDA, Cu-HA-DPA-Van microsphere materials were prepared, and the colony counting method was used to evaluate the antibacterial effect of the materials for Staphylococcus aureus. Various types of Cu-doped HA (Cu-HA) were successfully synthesized. As the proportion of Cu increased, the morphology gradually changed from being strip or belt-shaped to a uniform spherical shape. Cu-HA of 10% molar doping ratio showed a clearly microspherical shape and a petal-like porous micro-nano morphology on the surface. EDS and XRD analyses showed that the main structure of the material was still made up of hydroxyapatite crystals and Cu was successfully doped with HA. The infrared spectrometer showed that the PDA was successfully coated on the surface of the material. Examination of the main components of the extract solution once again verified that the Cu element had successfully entered and replaced part of the Ca element in the HA. The 10 mg/mL Cu-HA-PDA-Van extract solution contained 0.27 mg/mL of Van. In vitro cell experiments and bone-formation-related gene testing showed that Cu-HA-Van had good biological activity and promoted bone differentiation. The minimum inhibitory concentration (MIC) of Cu-HA-PDA-Van microspheres was 16 μg/mL. Compared with Cu-HA, HA-PDA and pure HA, Cu-HA-Van microspheres had significant and long-lasting antibacterial effects. Cu element was used to control the microscopic morphology of HA, and the Cu-HA-PDA-Van microspheres prepared by successfully coating of PDA and loading of Van had good antibacterial properties and biological activity.

Laryngopharyngeal Reflux Disease: Diagnosis and Treatment in 2021

Laryngopharyngeal reflux disease (LPRD) is an inflammatory condition of the upper aerodigestive tract mucosa induced by reflux content from stomach. Some of vocal cord diseases are associated with laryngopharyngeal reflux. Because of the pathophysiological features, proton pump inhibitor shows therapeutic effect on some vocal cord diseases. As like that, the gastric reflux contents can make macroscopic or microscopic morphological changes in the upper aerodigestive tract mucosa. Although the pathophysiology of LPRD is relatively clear, clinical diagnosis is still difficult. The diagnosis of LPRD includes objective tests such as 24-hours multichannel intraluminal impedance-pH metry and subjective tests such as questionnaire method. However, the objective verification of reflux is difficult due to invasiveness of the method, and the questionnaire methods have limitations because many symptoms are not specific for LPRD. Moreover, most methods are not fully standardized until now. Despite these limitations, many researchers are struggling to standardize diagnosis and treatment of LPRD, and there are several new achievements recently. Therefore, the purpose of this article is to review the recent literature on the clinical presentation, diagnosis, and treatment of LPRD, and to systematize our knowledge.

Crossing over the curing and degradation of DGEBA/MTHPA/Eggshell to disclose the reactionary system

Degradation mechanisms and curing on diglycidyl ether of bisphenol A/methyl tetrahydrophthalic anhydride with 2,4,6-tris (dimethylaminomethyl) phenol as synthetic catalyst or eggshell membrane as natural catalyst, i.e., DGEBA/MTHPA/DEH 35 and DGEBA/MTHPA/M, respectively, were investigated by thermogravimetry (TGA) and Fourier transform infrared spectroscopy (FTIR). Thermal stability as commonly reported by TGA in this work was followed up by FTIR, enabling to specify the produced chemical groups from each degradation step. Qualitative and quantitative evaluation of kinetics mechanisms using Friedman, Kissinger, Criado and Coats-Redfern models, were performed and the activation energy (Ea) was computed, as presented the degradation energy for eggshell membrane compound is lower than the curing one, contributing to the latter's favorability. Reactionary schemes based on the theoretical models are proposed in an attempt to macroscopically demonstrate the microscopic morphological changes and reactions.

Highly Selective and Sensitive Sulfonylhydrazone Type Fluorescent Probe for Rapid Detection of Mercury(II) and Its Application in Logic Gate and Adsorption

AbstractIn this study, 4‐bromotriphenylamine, 5‐formaldehyde thiophene‐2‐boronic acid and benzenesulfonyl hydrazide were used as materials to synthesize a novel type of Schiff base fluorescent probe molecule N′‐((5‐(4‐(diphenylamino)phenyl)thiophen‐2‐yl)methylene)benzenesulfonohydrazide (BS), and its structure was characterized by nuclear magnetic resonance (NMR) and high resolution mass spectrometry (HR‐MS). BS exhibited excellent solvatochromic effect and aggregation‐induced emission enhancement, and had rapid recognition, high selectivity and specificity for Hg2+, the detection limit was as low as 2.84×10−8 M, and the response time is only 15 s. It has passed the 1H NMR titration experiment verified its possible response mechanism. Through the good reversible performance of BS, molecular logic gate was constructed with Hg2+ and EDTA as chemical inputs. In practical applications, polyacrylamide (PAM) doped BS (PAM‐BS) could achieve high‐efficiency adsorption of Hg2+, with a removal rate of 99.93 %, and the microscopic morphology and element changes before and after PAM‐BS adsorption were compared by SEM‐EDS.

Influence of Mouthwash Rinsing on the Mechanical Properties of Polymeric Ligature Ties Used for Dental Applications.

Mouthwashes are used during dental treatments to mitigate the complications caused by poor oral hygiene. However, these solutions also affect the properties of dental appliances, including those used in orthodontics. This point has been investigated in this study focusing on the changes in mechanical properties of polymeric orthodontic ligature ties. Commercial ties from four brands were characterized in terms of their maximum forces and displacement, delivery forces, molecular structures, and microscopic morphology. These properties were compared against the ties, which were rinsed with commercial mouthwashes from three manufacturers. The results showed that mouthwash rinsing significantly reduced the maximum bearable forces of ligature ties by up to 73.1%, whereas the reduction in their maximum displacement was up to 74.5% across all tested brands. Significant changes in microscopic morphology of ligature ties were observed after mouthwash rinsing, but not their molecular structure. Furthermore, mouthwash rinsing also reduced the delivery forces from ligature ties by between 20.9 and 32.9% at their first deformation cycle. It can be concluded from this study that mouthwashes have significant impact on the mechanical properties of polymeric orthodontic ligature ties and could also potentially affect the overall efficacy of orthodontic and other dental treatments.

Stiff-Stilbene-Bridged Biscalix[4]arene as a Highly Light-Responsive Supramolecular Gelator.

A newly designed stiff-stilbene functionalized biscalix[4]arene in its cis form Z-1 could be near-quantitatively photoswitched to the trans-isomer E-1 under irradiation of 385 nm UV light. The trans-biscalix[4]arene E-1 was found to be a supergelator in nonpolar organic solvents, e.g., cyclohexane, hexane, pentane, and ether, with critical gelation concentrations as low as 0.2, 0.5, 0.5, and 0.4% w/v, respectively. The cis-trans configurational isomerism of biscalix[4]arene 1 resulted in distinct self-assembly modes, leading to interesting microscopic morphological changes from honeycomb and ringlike structures to rodlike dense fibrous networks.

Cytotoxic evaluation of two orthodontic silver solder materials on human periodontal ligament fibroblast cells and the effects of antioxidant and antiapoptotic reagents.

To evaluate the cytotoxicity effects of two different solder materials used for orthodontic appliances on human periodontal ligament fibroblast (HPLF) cells, and to determine whether the mechanism of toxicity may involve oxidative stress and apoptosis. The silver solder samples (Leone and Summit) were soldered to orthodontic stainless steel bands and exposed to HPLF cells via cell culture inserts for 48 hours. Cytotoxicity effect of the soldered materials on HPLF cells was measured via tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) colorimetric assay (n = 10/sample) and morphological observation. In addition, the mechanism of cytotoxicity of the most toxic silver solder was investigated using both a caspase inhibitor Z-VAL-Ala-Asp-flu-oromethylketone (ZVAD-fmk) and the free radical scavenger Trolox (n = 8/sample). Statistical analysis was performed using one-way analysis of variance with a Bonferroni test. P < .05 was considered statistically significant. Compared to the control (no treatment, cells only), both silver solders were cytotoxic (P < .001). The bands alone were significantly cytotoxic compared to the control. There was a significant difference in cytotoxicity between the stainless steel bands alone and the Summit silver solder (P < .001), but not the Leone silver solder. The Summit silver solder was more cytotoxic than the Leone silver solder (P < .05). MTT results were supported by the microscopic morphological changes of the HPLF cells. Neither ZVAD-fmk nor Trolox provided significant protection. The two silver solder materials demonstrated different levels of cytotoxicity, and neither oxidative stress nor apoptosis is involved in the mechanism of cytotoxicity.

Nutmeg extract potentially alters characteristics of white adipose tissue in rats.

BackgroundBrowning of white adipose tissue (WAT) is a promising approach to obesity treatment. During browning, WAT transforms into beige adipose tissue through stimulation of the peroxisome proliferator activated receptor γ (PPARγ). Nutmeg, one of the Indonesian herbs, reportedly has dual roles as a PPARα/γ partial agonist. Even though nutmeg has been traditionally used in body weight reduction, there is limited information regarding the potential role of nutmeg in browning of WAT.ObjectivesIn this study, we explored the effect of nutmeg seed extract (NuSE) as a potential inductor of WAT browning.MethodsTwelve male Wistar rats, 5–6 weeks old, were divided into control and nutmeg groups. The rats in nutmeg group were given NuSE for 12 weeks by oral gavage. After 12 weeks, the rat's inguinal WAT and brown adipose tissue (BAT) were collected, weighed and stored at − 80°C until use.ResultsWe observed that even though NuSE did not reduce the final body weight, it significantly reduced body weight gain. NuSE also increased protein levels of peroxisome proliferator activated receptor γ coactivator 1α (PGC‐1α) and uncoupling protein 3 (UCP3) significantly and tended to increase UCP2 and UCP1 levels. Furthermore, NuSE induced macroscopic and microscopic morphological changes of inguinal WAT, marked by significantly increased adipocyte numbers and decreased adipocyte size.ConclusionsEven though NuSE did not increase UCP1 significantly, it potentially alters inguinal WAT characteristics and leads to browning through PGC‐1α and UCP3 induction. However, UCP3’s specific mechanism in WAT browning remains unclear. Our findings could contribute to obesity treatment in the future.

Research on the Influencing Factors of the Strength of Lightweight High Strength Foamed Cement

In order to explore the factors affecting the strength of lightweight and high-strength foamed cement, ordinary Portland cement is used as the cementing material, and the target dry density is 400~410kg/m3 by controlling the content of foaming agent and foam stabilizer. Lightweight high-strength foamed cement specimen with strength of 4.4MPa. Controlling a single variable, the compressive strength and microscopic morphology changes of foamed cement specimens with different self-made reinforcing agent content and fly ash content were studied. The research results show that when the fly ash content is 20%, the strength of the sample without reinforcing agent reaches the best 2.4MPa; when 2wt% of the reinforcing agent is added, the strength of the sample reaches the maximum compressive strength of 4.4MPa, an increase of 83 %. Scanning electron microscope microscopic morphological observation results show that after adding the reinforcing agent, the foamed cement cell is more uniform, the cell wall becomes denser, and the cell defects are reduced, which explains the macroscopic advantages of lightweight and high-strength foamed cement.

Study on the influence of anisotropy of ZnGeP2 single crystal on its surface cutting quality

Improving the surface quality of ZnGeP2 is an important way to expand its application range. The anisotropy of the ZnGeP2 crystal affects the surface quality after material removal. Through the nano-indentation experiment of ZnGeP2 crystal, the anisotropy hardness and brittle plastic transformation depth were observed. The influence of anisotropy on the cutting process was verified by molecular dynamics simulation and diamond tool turning. The nano-scratch test was carried out on the surface of ZnGeP2, to analyze the range of plastic regions at different angles in combination with the microscopic morphology changes. Finally, cutting experiments in different directions of ZnGeP2 was carried out by diamond fly-cutting machine tool. The simulation and experiment results showed that the ZnGeP2 crystal is anisotropic and with the smallest cutting force along the [100] direction. During the fly-cutting process, when the cutting direction along 0° and 180°, the surface roughness value Sa could reach to 9.988 nm, the surface quality was higher than that in the other cutting directions.

Research on cutting mechanism of ZnGeP2 crystal under surface brittle-plastic transition by heating assistance

Improving the surface quality of the ZnGeP2 crystal is an important way to expand its application range. Given the high difficulty of processing the ZnGeP2 crystal, the research proposed a method of increasing the processing temperature of the material to expand the range of the plastic region, then improving the surface quality, the feasibility of the method was verified by heating assisted nanoindentation experiment and molecular dynamics simulation. The use of diamond tools to scribe the surface revealed the microscopic morphology changes of the ZnGeP2 crystal under high temperatures. Finally, with the assistance of heating, the surface of ZnGeP2 crystal was processed comprehensively by ultra-precision diamond fly-cutting machine, the experimental results showed that as the processing temperature increased, the surface quality of the ZnGeP2 crystal gradually improved, and the surface roughness Sa could reach to 9.426 nm. The effectiveness of improving the surface quality through heating assisted cutting was verified, which had guiding significance for the processing of other hard and brittle materials.

Membrane disruption of Fusarium oxysporum f. sp. niveum induced by myriocin from Bacillus amyloliquefaciens LZN01.

Myriocin, which is produced by Bacillus amyloliquefaciens LZN01, can inhibit the growth of Fusarium oxysporum f. sp. niveum (Fon). In the present study, the antifungal mechanism of myriocin against Fon was investigated with a focus on the effects of myriocin on the cell membrane. Myriocin decreased the membrane fluidity and destroyed the membrane integrity of Fon. Significant microscopic morphological changes, including conidial shrinkage, the appearance of larger vacuoles and inhomogeneity of electron density, were observed in myriocin-treated cells. A membrane-targeted mechanism of action was also supported by transcriptomic and proteomic analyses; a total of 560 common differentially expressed genes (DEGs) and 285 common differentially expressed proteins (DEPs) were identified. The DEGs were further verified by using RT-qPCR. The combined analysis between the transcriptome and proteome revealed that the expression of some membrane-related genes and proteins, mainly those related to sphingolipid metabolism, glycerophospholipid metabolism, steroid biosynthesis, ABC transporters and protein processing in the endoplasmic reticulum, was disordered. Myriocin affected the serine palmitoyl transferase (SPT) activity as evidenced through molecular docking. Our results indicate that myriocin has significant antifungal activity owing to its ability to induce membrane damage in Fon.

A comparison of the effects of different cap thicknesses on corneal nerve destruction after small incision lenticule extraction.

To evaluate the features of corneal nerve destruction after small incision lenticule extraction (SMILE) with different cap thicknesses (100 and 120μm). Nine consecutive patients (18 eyes) received SMILE with a 120-μm cap thickness and nine patients (18 eyes) with a 100-μm cap thickness were recruited. Confocal microscopy was used to evaluate the density and microscopic morphological changes of central corneal subbasal nerves preoperatively and at postoperative week 1. The postoperative corneal subbasal nerve densities decreased significantly in both 120μm and 100μm groups. No statistical difference was detected in reduction of subbasal nerve density between two groups (P = 0.299). The number of subbasal nerve fibers significantly decreased in both groups. The reductions were not significantly different between two groups (P = 0.293). Using a 120-μm cap thickness during SMILE preserves no more central corneal subbasal nerve fibers compared to a 100-μm cap thickness.

Comparison and study of the preparation methods for phosphor layer in nuclear battery

This work investigated the preparation and optimization of phosphor layer for radioluminescent nuclear battery, and analyzed the property change of the phosphor after irradiation. ZnS:(Cu, Al) with grain size of 5 μm was selected as the phosphor material, and AlGaInP semiconductor was used as the photovoltaic unit. Monte Carlo modeling was used to simulate energy deposition, absorbed dose, penetration of β particles in the phosphor. The optimized coupling scheme of radioisotope sources and phosphor layer was obtained based on comparison particle penetration depth and the output power of radioluminescent nuclear battery. The phosphor layer with 60Co γ-radiation enhanced the luminescence property up to 50% at the radiation dose of 871 kGy, which is considered as an optimized method of phosphor layer preparation. The radiation of 10 MeV electron was conducted to study the degradation based on the microscopic lattice characteristics, morphological changes, optical and electrical properties. Phosphors have excellent radiation resistance. The output power of nuclear batteries has only declined by 43% even when electron radiation dose reaches 8.56 MGy. The prospect for utilizing ZnS:(Cu, Al) phosphor as radiant energy conversion materials in nuclear battery was also discussed. Results provided an effective guideline for predict the service conditions of radioluminescent nuclear battery.

Aging behaviors of bitumen degraded by the microbial consortium on bituminous pavement

As bituminous pavement is under the shady, humid or polluted environments, the bitumen undergoes the microbial degradation by different microorganisms to cause the aging. To understand the microbial aging of bitumen degraded by multiple microorganisms, the typical bacillus licheniformis (BL), bacillus subtilis (BS) and pseudomonas aeruginosa (PA) were selected to compound three microbial consortia in different proportions, and cultured in three culture mediums. A more suitable culture medium for the three microbial consortia is selected. The changes in microscopic morphology, components, molecular weight distributions, functional groups and micromechanical properties of aged bitumen were discussed. Results indicate that the peptone content change of culture medium obviously affects the propagation of microbial consortia. The prepared culture medium II meets the propagation requirements of the three microorganisms, improving their degradation ability. Additionally, the microbial consortia preferentially degrade bituminous light components as their nutrient sources, and show weak degradation ability to macromolecular components, producing potholes with layer structures on bituminous surface. Moreover, the smaller molecules are decreased, but the macromolecules are increased in aged bitumen. The molecular weight distribution of aged bitumen is narrowed. BS, BL and PA in the microbial consortium of S2 show better synergistic effect to efficiently degrade bitumen than those of S1 and S3. Finally, the carbonyl and sulfoxide contents are not changed obviously, but the methylene content is decreased to reflect the aging results of bitumen. The maximum adhesive force of aged bitumen is lowered to cause the decrease in adhesion work, reflecting the decrease in bituminous viscidity. The elastic modulus of bitumen shows an increasing trend as the aging duration is prolonged. The elastic modulus of aged bitumen by the microbial consortium of S2 is higher than those by S1 and S3. This study provides an insight into the microbial aging mechanism of bitumen by multiple microorganisms.