The Hole Sealing Technology of Solid-Liquid Materials with Three Pluggings and Two Injections for Gas Extraction Hole in the Coal Mine.

The sealing quality of the gas extraction holes determines the extracted gas concentration. Based on this, the paper reveals the basic principle of hole sealing by analyzing the gas leakage mechanism of the borehole. The hole sealing technology of solid-liquid materials with three pluggings and two injections for the gas extraction hole is proposed, and the hole sealing device and material are developed. Through testing the granularity distribution of the solid material, as well as the surface tension and contact angle of the slurry, the hole sealing material that can meet the requirements of accessible, sticky, and anti-deformation is selected. The sealing material enters microcracks and bonds coal rock more easily. First, the solid material is injected for hole sealing. Second, the liquid material can be injected repeatedly to maintain a high concentration for holes with poor sealing and gas concentration attenuation in the late stage of gas extraction. Field tests show that the gas concentration of solid material is 1.3 times that of the conventional material after 30 days of sealing. The liquid material injected after the concentration decline enables the gas extraction concentration to be recovered at 85%.

Effects of amylose and amylopectin molecular structures on starch electrospinning.

The role of amylose content in electrospinning starch nanofibres is well understood, but that is not the case for the roles of the molecular structures of amylose and amylopectin. Here, correlations between starch molecular-structure parameters and electrospinnability evaluation indices (average droplet number, average bead number, and average fibre diameter) and dope properties (shear viscosity, conductivity, and surface tension) were examined. Starches with lower amounts of short amylopectin chains, higher amounts of either/or long amylopectin chains and/or lower degree of branching showed decreased viscosity of the electrospinning dopes, and resulted in a reduced average droplet number of electrospun fibre mats. The molecular sizes of amylose and whole starch, and the average degree of polymerization for amylose chains, all correlated with the shear viscosity and surface tension of dopes, and thus influenced the average fibre diameter. This expands the current understanding between amylopectin molecular structure and starch electrospinning, thereby assisting a better choice of starches for desired electrospinnability properties.

Combined effects of starch fine molecular structures and water content on starch digestibility of cooked white rice.

Although the starch digestibility of cooked white rice has been investigated with regard to its relation to starch structure, it is not yet clear how starch molecular structure and water content affect its digestion rate. To investigate this, the in vitro starch digestibility and molecular structure of 10 rice varieties with a range of rice-to-water cooking ratios were investigated. As expected, starch digestibility varied with different conditions. Typically, a higher amylose content resulted in a lower maximum digestion extent for a given water content. Having relatively more and longer amylopectin intermediate chains caused a slower starch digestion rate, but only with rice-to-water ratios between 1:1 and 1:1.2. These results could prove useful to find combinations of starch fine molecular structures and water contents to produce cooked rice with low glycemic index.

Prediction of product yields using fusion model from Co-pyrolysis of biomass and coal.

This study aimed to establish a self-corrective machine learning model base on co-pyrolysis data of biomass and coal. Proximate and ultimate analysis of raw materials were chosen as input parameters. Radial basis function (RBF), support vector machine (SVM), and random forest (RF) were used to build the base regression models for the fusion (FU) model. 96 sets of the experimental data were applied to train and test the base models. A learning weight were then determined by the predicted performance of base models. Based on the learning weight method, FU model spontaneously regulated and controlled the weight of base models to output the predicted result of co-pyrolysis products. The coefficient of determination (R2) was more than 0.99 and the root-mean-squared error (RMSE) was lower than 0.88%. The results suggested that FU model was more accurately adequate to forecast the yields of co-pyrolysis products than any of the base models.

Effects of Nonstarch Genetic Modifications on Starch Structure and Properties.

This paper examines if, in maize, starch structure and starch-dependent properties might be altered by pleiotropic effects arising from genetic modifications that are not directly related to starch synthesis. The molecular structure, specifically the starch chain-length distributions (CLDs), of two maize lines transformed with Bar (bialaphos resistance) and Cry1c genes (an artificial gene, encoding proteinaceous insecticidal δ-endotoxins) were compared to those of their control lines. The two transgenes are responsible for herbicidal resistance and insect tolerance, respectively. The starch CLDs were measured by enzymatic debranching and measuring the molecular weight distributions of the resulting linear chains. It was found that although all the lines had similar amylose contents, the CLDs of both amylopectin and amylose for Cry1c were noticeably different from the others, having more short amylopectin and long amylose chains. These CLDs are known to affect functional properties, and indeed it was found that the Cry1c transgenic lines showed a lower gelatinization temperature and faster digestion rate than the control or Bar lines. However, a slower digestion rate is nutritionally desirable. Thus, pleiotropic effects from genetic modifications can indirectly but significantly affect the starch synthesis pathway and thus change functional properties of significance for human health.

A starch molecular basis for aging-induced changes in pasting and textural properties of waxy rice.

The gelatinization behavior of rice flour and isolated starch and the texture of cooked rice were examined both for fresh and aged samples successively. The whole and debranched starch molecular structures of the starches extracted from the flour and hot water-washed leachate of the cooked rice were characterized, using size-exclusion chromatography, to elucidate the molecular origins of the functional changes. For all variety, the native and leached starches of the aged rice had significantly smaller average total molecular sizes, higher proportions of short amylopectin chains, and smaller average chain length of amylopectin compared to fresh rice. The structural changes are consistent with the observed higher peak and final viscosity, lower pasting temperature, greater hardness and lower stickiness of cooked rice kernels for aged rice, based on established structure-property relationships. This study can be used to suggest ways in which some improved functional properties could be obtained with less expenditure for storage.

Molecular structural differences between maize leaf and endosperm starches.

The morphology, whole molecular size distribution and chain-length distribution of maize leaf starch have been characterized and compared to its endosperm starch, to better understand differences between leaf and endosperm starch structure, and the relationship with the functions of starch in these organs. Leaf starch is found to have amylopectin with much shorter chains (virtually none with a degree of polymerization, DP, above 70) than the endosperm amylopectin, which has significant numbers of chains with DP up to ∼120, and has much smaller molecular size (and is present at a much lower amount) than endosperm starch. It is postulated that these pronounced differences arise from the distinct starch synthesis pathways in these organs, and are consistent with the starches' distinct botanical functions: short-term storage requiring relatively rapid degradation for leaf starch, and high crystallinity and high energy density requiring slow degradation for endosperm starch.

Detection of intestinal bifidobacteria and lactobacilli in patients with Hirschsprung's disease associated enterocolitis.

BACKGROUND: The etiology of Hirschsprung's disease associated enterocolitis (HAEC) is unknown. Previous investigations have suggested that several factors such as dilation of proximal bowel, changes in colonic mucosal defence, and overgrowth of toxigenic bacteria may be related with it. This study was to quantify bifidobacteria and lactobacilli in the feces of Hirschsprung's disease (HD) patients with or without enterocolitis and those of normal children. METHODS: Fresh stool specimens were collected at the first three days of the admission from 30 HD patients (aged 2 weeks to 2 years) and 15 healthy age-matched non-HD patients in the morning once a day for at least three days. All of them have not been given probiotics or antibiotics at least 7 days before stool collection. Hematoxylin-eosin and acetylcholinesterase histochemical staining on rectal biopsies of patients with HD confirmed the diagnosis of HD in all 30 patients. The 30 HD patients were divided into two groups based on the clinical history of enterocolitis: the HAEC group (n=10) and HD group (n=20). Fecal bifidobacteria and lactobacilli were consecutively quantified by SYBR Green I-based real-time PCR assay. Data were analyzed using SAS v. 12.6 for Windows. All tests were two-tailed, and P values <0.05 were considered statistically significant. RESULTS: The mean levels of bifidobacteria were 7.35+/-0.59, 8.16+/-1.17, and 8.35+/-0.74 in the HAEC, HD and control groups, respectively. The bifidobacteria colonization levels were lower in the HAEC group than in the HD and control groups (P<0.05, P<0.001 respectively). The mean level of lactobacilli in the HAEC (5.51+/-0.65) and HD groups (5.87+/-0.78) was significantly lower than that in the control group (6.39+/-0.56) (P<0.05). But there was no difference in log numbers of lactobacilli between HAEC and HD groups (P>0.05). CONCLUSIONS: The scarcity of bifidobacteria and lactobacilli in HAEC patients may result in a decrease in epithelial barrier function and be a predisposing factor in the development of HAEC. This decline suggests that treatment with probiotics or prebiotics may be beneficial in these individuals. Further research will focus on whether probiotics can decrease the incidence of HAEC.

The use of a retrievable self-expanding stent in treating childhood benign esophageal strictures.

BACKGROUND/PURPOSE: Esophageal stenting is a popular form of treatment of esophageal strictures in adults but is not widely used in children. The aim of the current study was to investigate whether esophageal stents could be used safely and effectively in the treatment of esophageal stenosis in children. METHODS: Covered retrievable expandable nitinol stents were placed in 8 children with corrosive esophageal stenosis. The stents were removed 1 to 4 weeks after insertion. RESULTS: The stents were placed in all patients without complications and were later removed successfully. After stent placement, all patients could take solid food without dysphagia. Stent migration occurred in one patient and so the insertion procedure was repeated to reposition the stent. During the 3-month follow-up period after stent removal, all children could eat satisfactorily. After 6 months, 2 children required balloon dilation (3 times in one and 5 times in the other). The dysphagia score improved in all patients. CONCLUSIONS: The use of the covered retrievable expandable stent is an effective and safe method in treating childhood corrosive esophageal stenosis.