Low-intensity mixing process of high molecular weight polymer chains leads to elastomers of long network strands and high fatigue threshold.

Many polymer networks are prepared by crosslinking polymer chains. The polymer chains and crosslinkers are commonly mixed in internal mixers or roll mills. These intense processes break the polymer chains, lower viscosity, and ease mixing. The resulting polymer networks have short chains and a fatigue threshold of ∼100 J m-2. Here, we show that a low-intensity process, a combination of kneading and annealing, preserves long chains, leading to a network of polybutadiene to achieve a fatigue threshold of 440 J m-2. In a network, each chain has multiple crosslinks, which divides the chain into multiple strands. At the ends of the chain are two dangling strands that do not bear the load. The larger the number of crosslinks per chain, the lower the fraction of dangling strands. High fatigue threshold requires long strands, as well as a low fraction of dangling strands. Once intense mixing cuts chains short, each short chain can only have a few crosslinks; the strands are short and the fraction of dangling strands is high-both lower the fatigue threshold. By contrast, a low-intensity mixing process preserves long chains, which can have many crosslinks; the strands are long and the fraction of dangling strands is low-both increase the fatigue threshold. It is hoped that this work will aid the development of fatigue-resistant elastomers.

Enteral nutrition support for lysinuric protein intolerance: a case report and literature review / 中国当代儿科杂志

OBJECTIVES@#To summarize the clinical characteristics and nutrition therapy for children with lysinuric protein intolerance (LPI).@*METHODS@#The clinical manifestations, laboratory test results and enteral nutrition treatment in a girl with LPI diagnosed in Xiangya Hospital, Central South University were retrospective analyzed. Additionally, the data of the children with LPI reported in China and overseas were reviewed.@*RESULTS@#A case of 4-year-old girl was presented, who exhibited significant gastrointestinal symptoms, such as chronic abdominal distension, prolonged diarrhea, recurrent pneumonia, and limited growth. She had a poor response to anti-infection treatment. After receiving enteral nutrition therapy, she did not experience any gastrointestinal discomfort, and there were improvements in the levels of hemoglobin, albumin, and blood ammonia. Unfortunately, due to serious illness, she declined further treatment and later passed away. A total of 92 cases of pediatric patients with LPI have been reported to date, including one case reported in this study. Most children with LPI experienced disease onset after weaning or introduction of complementary foods, presenting with severe digestive system symptoms, malnutrition, and growth retardation. It is noteworthy that only 50% (46/92) of these cases received nutritional therapy, which effectively improved their nutritional status. Among the 92 children, 8 (9%) died, and long-term follow-up data were lacking in other reports.@*CONCLUSIONS@#LPI often involves the digestive system and may result in growth restriction with a poor prognosis. Nutritional therapy plays a crucial role in the comprehensive treatment of LPI.

Efficacy and safety of pterygium resection respectively combined with Ologen collagen matrix implantation and autologous conjunctival flap transplantation / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To analyze the efficacy and safety of pterygium resection respectively combined with Ologen collagen matrix implantation and autologous conjunctival flap transplantation.METHODS:A total of 80 patients(87 eyes)with pterygium admitted to the hospital between January 2017 and January 2020 were selected, and randomly divided into observation group(40 patients, 44 eyes)treated with pterygium resection combined with Ologen collagen matrix implantation and control group(40 patients, 43 eyes)treated with pterygium resection combined with autologous conjunctival flap transplantation. The patients were followed up till 12mo after operation. The best corrected visual acuity, corneal astigmatism, surface asymmetry index(SAI), surface regularity index(SRI), corneal epithelial healing, pterygium recurrence and the incidence of complications were compared between the two groups. RESULTS:Visual changes of the two groups were similar at 6 and 12mo after operation(<i>P</i>>0.05). Corneal astigmatism, SAI and SRI were reduced in the two groups at 1 and 3mo after operation. The corneal astigmatismat 3mo after operation and SAI, SRI at 1 and 3mo after operation were significantly lower in the observation group than in the control group(all <i>P</i><0.05). The corneal epithelial healing rate in observation group at 1wk after operation was significantly higher than that in the control group(73% <i>vs</i> 46%, <i>P</i><0.05), and corneal epithelium of the two groups healed at 2wk after operation. No pterygium recurrence was observed in the two groups within 12mo after operation. The situation of pterygium recurrence was similar in the two groups at 6 and 12mo after operation(<i>P</i>>0.05). There was no significant difference in the incidence of complications between the two groups(7% <i>vs </i>14%, <i>P</i>>0.05).CONCLUSION:Both pterygium resection combined with Ologen collagen matrix implantation and pterygium resection combined with autologous conjunctival flap transplantation are effective in the treatment of pterygium, with equivalent safety. However, the former has more advantages in improving corneal astigmatism and regular shape of corneal wound.

Effects of vegetation type on the microbial characteristics of the fissure soil-plant systems in karst rocky desertification regions of SW China.

In karst regions, shallow karst fissure (SKF) soil has proven to be an important plant habitat and soil resource. However, how plants affect the microbial abundance and community composition of SKF soil remains poorly studied. We explored the soil microbial community structure differences in fractured soil-plant systems by determining phospholipid fatty acid (PLFA) profiles under three vegetation types (herbs, shrubs and trees) in SKF and used a bare SKF without vegetation as the control in a karst rocky desertification area. The total microbial biomass and microbial community composition differed between surface soil and SKF soil. The total microbial biomass in surface soil was higher than that in SKF soil. In addition, in contrast to surface soil, the microbial communities in SKF soil were more vulnerable to the effects of environmental variables. Furthermore, plants had a significant positive effect on the accumulation of microbial biomass in surface and SKF soil: shrubs had the strongest effect, followed by trees. Vegetation types significantly affected the ratios of saturated PLFAs to monounsaturated PLFAs (SAT/MONO ratio) and cyclopropyl PLFAs to precursors (cy/pre ratio). In contrast to the SKF without vegetation, the SAT/MONO ratio and cy/pre ratio under grasslands, shrublands and trees were low. Herbs and shrubs had the greatest capacity to enhance the ability of soil to respond to environmental stress compared to trees. Our results suggest that, as an important plant habitat in karst regions, the condition of SKF soil should be urgently improved. The stereoscopic collocation of shrub-grass vegetation may be the preferred measure for vegetation restoration. Deep-rooted shrubs and grasses are best at improving soil and plant growth. Our study can be useful for developing strategies for vegetation rehabilitation in karst regions.

Small - incision cataract extraction combined trabeculectomy for primary angle-closure glaucoma with cataract / 国际眼科杂志(Guoji Yanke Zazhi)

To observe the curative effect of treating small -incision cataract extraction by intraocular lens implantation combined with trabeculectomy for primary angle-closure glaucoma with cataract. ●METHODS: Totally 44 cases (52 eyes) of primary angle-closure glaucoma combined with cataract were selected to undergo the combined surgery, in order to observe the patients' pre - and postoperative eyesights, intraocular pressures and the postoperative complications. ●RESULTS: The postoperative eyesight was improved significantly as compared with the preoperative eyesight. The intraocular pressure was declined dramatically. The result was of statistical significance (P ● CONCLUSlON: Treating the primary angle - closure glaucoma combined with cataract through the combined surgery has high reliability and desirable curative effect. The surgical method is simple to learn and applicable for promotion on the basic level.

[Analysis on vegetations spectral characteristics along the altitudinal gradients in south-facing slope of Dangxiong Valley].

The present study focused on variation of vegetation types and canopy spectra along the altitudinal gradients in south-facing slope of Dangxiong valley in Tibet. Spectral extraction methods including red edge analysis and vegetation indices were used for vegetation spectral characteristics analysis. Through the hierarchical clustering analysis based on the vegetation spectral features, the feasibility of remote sensing classification of vegetation types along the elevation gradients in the experimental area was evaluated. The experimental results showed that: there were significant differences in spectral features including water index (WI), red edge POSITION (REP), and normalized difference vegetation index (NDVI) in different plots along elevation gradients in the study area, and there were strong correlations between WI and leaf water content, REP and dry biomass, NDVI and vegetation coverage. The hierarchical clustering analysis result of 12 vegetation samples along the altitudinal gradients is consistent with the ground survey, which shows that the selected vegetation spectral features can characterize the vertical distribution of vegetation types in the experimental area. The vegetation spectral analysis in this study can provide the priori knowledge support of spectral characteristics for the vegetation vertical distribution information extraction in the Tibet Plateau.

[Observation of CT three-dimensional reconstruction in the treatment of standard manipulation for lumbar intervertebral disc herniation].

OBJECTIVE: To observe the morphological change of prominence through CT three-dimensional reconstruction before and after manipulative treatment and in order to investigate biomechanical effect of manipulation in treating lumbar intervertebral disc herniation (LIDH). METHODS: From December 2009 to May 2010, 24 patients with LIDH (32 herniated discs) with the unilateral typing,which were treated with manipulation (on alternate day one time and every time about 20 min, 3 weeks as a course of treatment). There were 10 males and 14 females, ranging in age from 25 to 54 years with an average of 36.2 years, in course of disease from 2 days to 10 years with an average of 6.9 years. Protrusible 12 discs were in L4,5 and 20 discs were in L5S1. According to typing of distance between prominence and zygapophysial joint or vertebral plate (ligamentum flavum), 5 cases were type I, 13 cases were type II and 6 cases were type III. After a course of treatment,the morphological changes of prominences were analyzed in the same level of CT three-dimensional reconstruction, including contour map of nerve root sheath side distance (TD), the distance between prominence and zygapophysial joint or vertebral plate (ligamentum flavum), the deviated angle of prominence (AN value) and the sagittal index (SI value). RESULTS: From the contour map of TD, 19 patients (79.2% of the total) can be identified morphological changes after the treatment; from the distance between prominence and zygapophysial joint or vertebral plate (ligamentum flavum), 7 cases with type II turned into type I and 2 cases with type III turned into type II after treatment; AN value increased after treatment (P<0.05),it showed prominence occurred morphological change toward deviated direction of intervertebral foramina; there was no significant difference in SI value between before and after treatment (P>0.05). CONCLUSION: Standard manipulation can make prominence change, the prominence and nerve roots release, and mutual position improve,which can provide imaging evidence for the study in biomechanical effects.