Calcined flint clay (45.6 wt.% Al2O3) and solid waste coal gangue were used to prepare low-density ceramic proppant by solid state sintering method. The density and breakage ratio of the ceramic ...proppant were systematically investigated as a function of sintering temperature. The morphology and phase composition of the ceramic proppant were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the ceramic proppant is composed of rod-like mullite and granular cristobalite. Bulk density and apparent density of the proppant first rise and then slightly decrease with increasing the sintering temperature, while breakage ratios under 35 MPa and 52 MPa pressure gradually decrease and then increase. As the sintering temperature increases up to 1400 °C, the ceramic proppant shows denser microstructure. The proppant sintered at 1400 °C have the best performance with 1.27 g/cm3 of bulk density, 2.79 g/cm3 of apparent density, 3.27 % of breakage ratio under 35 MPa closed pressure and 8.36 % of breakage ratio under 52 MPa closed pressure, which conform to the requirement of low-density ceramic proppant. The addition of solid waste can greatly reduce the preparation cost of the ceramic proppant.
Skull stripping remains a challenge for neonatal brain MR image analysis. However, little is known about the accuracy of how skull stripping affects the neonatal brain tissue segmentation and ...subsequent network construction. This paper therefore aimed to clarify this issue by comparing two automatic (FMRIB Software Library's Brain Extraction Tool, BET; Infant Brain Extraction and Analysis Toolbox, iBEAT) and a semiautomatic (iBEAT with manual correction) processes in constructing 3D T1-weighted imaging (T1WI)-based brain structural network.
Twenty-two full-term neonates (gestational age, 37-42 weeks; boys/girls, 13/9) without abnormalities on MRI who underwent brain 3D T1WI were retrospectively recruited. Two automatic (BET and iBEAT) and a semiautomatic preprocessing (iBEAT with manual correction) workflows were separately used to perform the skull stripping. Brain tissue segmentation and volume calculation were performed by a Johns Hopkins atlas-based method. Sixty-four gray matter regions were selected as nodes; volume covariance network and its properties (clustering coefficient, C
; characteristic path length, L
; local efficiency, E
; global efficiency, E
) were calculated by GRETNA. Analysis of variance (ANOVA) was used to compare the differences in the calculated volume between three workflows.
There were significant differences in volumes of 50 brain regions between the three workflows (P < 0.05). Three neonatal brain structural networks presented small-world topology. The semiautomatic workflow showed remarkably decreased C
, increased L
, decreased E
, and decreased E
, in contrast to the two automatic ones.
Imperfect skull stripping indeed affected the accuracy of brain structural network in full-term neonates.
Bilateral cerebral palsy (BCP) is a common movement disorder in children, which often results in lifelong motor disability. One main symptom of BCP shows the limitations of hand function in everyday ...activities and participation restrictions. However, the neuroanatomical mechanisms for the manual ability are poorly understood. Recent advances in the understanding of cerebral palsy include the development of coordinated pairwise gray matter, which is important for sensorimotor integration, and cognitive development. Here, in our study, neuroimaging with network analysis was employed to evaluate the changes of structural covariance networks (SCNs) in Chinese BCP children. We aimed to elucidate the alteration of SCNs based on cortical thickness (CT), and to reveal the relationship of CT and hand function in the participants with BCP. SCNs were constructed using covariance between regional CT, which was acquired from T1-weighted images of 19 children with BCP and 19 demographically matched healthy controls (HCs). Compared with HCs, BCP children showed increased CT in several regions involving the bilateral areas (lateraloccipital, lingual, and fusiform) and right areas (cuneus, pericalcarine, inferiortemporal, middletemporal, superiortemporal, and insula). Decreased CT was found in the left superior temporal and right superior parietal cortices. Global network analyses revealed significantly decreased normalized clustering and small-worldness in the BCP network. The area under the curve (AUC) of global network measures varied slightly between the BCP and HCs networks. The resistance of the both SCNs to the target and random attack showed no significant difference. Also, the BCP foci (right superior temporal and subtemporal cortex) showed a significantly negative correlation between the CT and manual ability. In this work, we identified the CT-based SCNs changes in Chinese children with BCP. The abnormal topological organization of SCNs was revealed, indicating abnormal CT, incongruous development of structural wiring, destructive nodal profiles of betweenness, and moved hub distribution in BCP children. This may provide a neuroanatomical hallmark of BCP in the developing brain. Therefore, our results may not only reflect neurodevelopmental aberrations but also compensatory mechanisms.
Green fir wood (Pseudotsuga menziesii) was modified with polyethylene glycol (PEG) to produce wood composites for energy storage and conversion. The PEG-modified wood composites were evaluated based ...on their dimensional stability, durability, and thermal properties by various analytical methods. The differential scanning calorimetry (DSC) results showed the melting temperature and the latent heat of the phase change material (PCM) composite were 26.74 °C and 73.59 J/g, respectively. Thermal cycling tests and thermogravimetric analysis confirmed the composite exhibited good thermal stability, reliability, and chemical stability. All treated specimens were free from noticeable defects, and the addition of a surface varnish coating prevented PEG from leaching. The PEG-modified composites exhibited improved dimensional and thermal performance, which makes this material a potential candidate for economical and green, lightweight building materials.
Quizalofop-p-ethyl (QPE), a unitary R configuration aromatic oxyphenoxypropionic acid ester (AOPP) herbicide, was widely used and had led to detrimental environmental effects. For finding the ...QPE-degrading bacteria and promoting the biodegradation of QPE, a series of studies were carried out.
A QPE-degrading bacterial strain YC-XJ1 was isolated from desert soil and identified as Methylobacterium populi, which could degrade QPE with methanol by cometabolism. Ninety-seven percent of QPE (50 mg/L) could be degraded within 72 h under optimum biodegradation condition of 35°C and pH 8.0. The maximum degradation rate of QPE was 1.4 mg/L/h, and the strain YC-XJ1 exhibited some certain salinity tolerance. Two novel metabolites, 2-hydroxy-6-chloroquinoxaline and quinoxaline, were found by high-performance liquid chromatography/mass spectroscopy analysis. The metabolic pathway of QPE was predicted. The catalytic efficiency of strain YC-XJ1 toward different AOPPs herbicides in descending order was as follows: haloxyfop-p-methyl ≈ diclofop-methyl ≈ fluazifop-p-butyl > clodinafop-propargyl > cyhalofop-butyl > quizalofop-p-ethyl > fenoxaprop-p-ethyl > propaquizafop > quizalofop-p-tefuryl. The genome of strain YC-XJ1 was sequenced using a combination of PacBio RS II and Illumina platforms. According to the annotation result, one α/β hydrolase gene was selected and named qpeh1, for which QPE-degrading function has obtained validation. Based on the phylogenetic analysis and multiple sequence alignment with other QPE-degrading esterases reported previously, the QPEH1 was clustered with esterase family V.
M. populi YC-XJ1 could degrade QPE with a novel pathway, and the qpeh1 gene was identified as one of QPE-degrading esterase gene.How to cite: Li X, Wang J, Wu W, et al. Co-metabolic biodegradation of quizalofop-p-ethyl by Methylobacterium populi YC-XJ1 and identification of QPEH1 esterase. Electron J Biotechnol 2020;46. https://doi.org/10.1016/j.ejbt.2020.05.003.
To elucidate the phase transformation behaviors for 38MnB5Nb ultra high-strength steel, the continuous cooling transformation (CCT) and time-temperature-transformation (TTT) curves were determined by ...the thermal expansion method with different cooling rates and isothermal temperatures after complete austenization. To be more accurate, the microstructure was observed and the hardness was tested. The results showed that the starting and ending transformation temperatures of austenite during heating are 748 °C and 805 °C, respectively. Bainite’s start temperature is between 540 °C and 550 °C, while martensite’s start temperature is about 310 °C. The critical cooling transformation rate is between 10 °C/s and 15 °C/s. The results showed that the microstructures are severely related to the cooling rate during the continuous cooling process and are related to isothermal temperatures during the isothermal process. The relationship between hardness and the microstructure was investigated and hardness is severely related to the microstructure. Based on the results of CCT curves compared with the conventional 22MnB5 hot stamping steel, the studied 38MnB5Nb steel is more beneficial for selective cooling processes.
To elucidate the hardness evolution behaviors for 38MnB5Nb ultra-high-strength hot stamping steel, a series of tempering processes with varying tempering temperatures and times were carried out with ...a dilatometer. Meanwhile, the hardness of each sample was measured after dilatometer experiments. The results indicated that the tempering process parameters (including the tempering temperature and time) play an important role in the hardness of the studied steel. The hardness of 38MnB5Nb ultra-high-strength hot stamping steel at the quenched state is about 580 Hv, while it is 240 Hv for the quasi-annealed state. As the tempering time extends, the hardness is decreased sharply at the initial stage; then, the hardness is decreased in a quasi-linear trend with a slight slope; finally, the hardness almost keeps a constant value, which depends on the tempering temperature. In addition, the tempering process has a big effect on the mechanical properties of 38MnB5Nb ultra-high-strength hot stamping steel by increasing the product of the strength and elongation by about 40%.
•The innovative grouts with high mortar ratio are prepared by ternary complex system.•The grouts have the performance of super early strength.•The grouts have 2h and 28d compressive strength of ...42.6MPa and 96.3MPa.•The grouts have no retraction of late strength and possess micro-expansion.•The grouts have high initial fluidity and low fluidity loss.
An innovative research on preparation of super early strength grouts is presented. A ternary complex system of sulphoaluminate cement, aluminate cement and gypsum was used in the grouts combined with a variety of additives. The effect of mortar ratio on the properties of grouts was studied, and the microstructure was observed. The results show that high mortar ratio can prepare super early strength grouts; 2h and 90d compressive strength of the grouts is 42.6 and 105.6MPa, respectively. Furthermore, the grouting material has no retraction of late strength and possesses micro-expansion property, which attribute to the formation of ettringite.
Double long-chain cationic surfactants (DLCS) were used for higher olefin hydroformylation catalyzed by water-soluble rhodium catalyst in the aqueous/organic biphasic system. The reaction rate was ...greatly accelerated and the TOF (turn over frequency defined as the moles of converted olefin per mole Rh per hour) in 1-dodecene hydroformylation achieved 2291
h
−1 even without stirring.
▪
The double long-chain cationic surfactants (DLCS) were used in higher olefin hydroformylation catalyzed by water-soluble rhodium catalyst in aqueous/organic biphasic system. The reaction rate was greatly accelerated and the value of TOF (turn over frequency defined as the moles of converted olefin per mole Rh per hour) in 1-dodecene hydroformylation could achieve 2291
h
−1 even without stirring. When the reaction was carried out with stirring rate of 400
rpm, TOF increased to 7472
h
−1. These values of TOF were comparable with that in homogeneous catalysis system. The phenomenon is attributed to the formation of vesicle and the enrichment of rhodium catalyst in the interfacial layer, as well as the high transfer rate of olefins from the organic phase to the interface of vesicle. The acceleration mechanism of DLCS in biphasic catalysis was discussed.
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