Cardiovascular disease(CVD)is often accompanied by chronic kidney disease(CKD)and metabolic disorders such as obesity and type 2 diabetes^([1]).The coexistence of these conditions can lead to systemic dysfunction and ...Cardiovascular disease(CVD)is often accompanied by chronic kidney disease(CKD)and metabolic disorders such as obesity and type 2 diabetes^([1]).The coexistence of these conditions can lead to systemic dysfunction and substantially increase adverse cardiovascular outcomes.To describe this interplay,the American Heart Association(AHA)recently proposed the concept of cardiovascular-kidney-metabolic(CKM)syndrome^([1]).However,its risk-enhancing factors and underlying mechanisms remain unclear.展开更多
The response of lake environments in arid Central Asia to climate change during the Late Holocene over the centennial to millennial timescales remains contentious.The reason that primarily paleoenvironmental proxies d...The response of lake environments in arid Central Asia to climate change during the Late Holocene over the centennial to millennial timescales remains contentious.The reason that primarily paleoenvironmental proxies diverse and the scarcity of accurate quantitative reconstruction records.In this study,we employed diatoms and pollen records from lacustrine sediment in the Aibi Lake of Southwest Junggar Basin to quantitatively reconstruct salinity and watershed precipitation amounts while exploring the associated forcing mechanisms.The results indicate that Aibi Lake salinity varied between 2 and 47 g/L during the Late Holocene Period,indicating a generally brackish environment,and corresponding to prevailing Tryblionella granulata diatom in the lake basin.Westerly-dominated annual precipitation varied between 250 and 320 mm during the Late Holocene Period in the basin,exhibiting a generally semi-arid environment and prevailing desert steppe vegetation.The Aibi Lake has a low salinity of average value of~15 g/L and exhibits elevated precipitation(average value of~280 mm)during the periods of the 2900-1990,1570-1140,and 590-120 cal yr BP.The reconstructed precipitation and salinity exhibit a periodicity of~200 years,which is consistent with the cycle of phase changes of the North Atlantic oscillation(NAO)and total solar irradiance(TSI).This correlation suggests that variations in NOA and TSI significantly influence the precipitation and salinity changes in Central Asia over centennial to millennial timescales.展开更多
With the continuous penetration of artificial intelligence(AI)in higher education,the organizational mechanisms and implementation logic of ideological and political education are undergoing new evolutionary trends.Th...With the continuous penetration of artificial intelligence(AI)in higher education,the organizational mechanisms and implementation logic of ideological and political education are undergoing new evolutionary trends.These technologies have been widely embedded in key aspects such as teaching management,student services,and value guidance,playing an increasingly prominent role in student status recognition,precise information distribution,and dynamic behavioral interventions.In the practice of ideological and political education in universities,intelligent systems have had a profound impact on the way educational content is supplied and the modes of interaction,shifting the approach from being experience-driven to data-guided.Meanwhile,the task structure of university education scenarios has become more complex,with highly heterogeneous student behaviors,value orientations,and demand preferences,leading to significant challenges for traditional ideological education models in terms of response efficiency and intervention accuracy.Against this background,this paper,based on the trend of digital evolution in ideological and political work in universities,systematically outlines the logical structure and key pivot points in the process of AI integration.It further proposes a fusion strategy composed of“intelligent perception-collaborative services-data-driven”to provide theoretical support and practical pathways for the intelligent transformation of the education system in the new era.展开更多
With the rapid development of IoT technology,the Fundamentals of IoT Hardware course—one of the core subjects in university IoT programs—urgently requires innovation and improvement in both its content and teaching ...With the rapid development of IoT technology,the Fundamentals of IoT Hardware course—one of the core subjects in university IoT programs—urgently requires innovation and improvement in both its content and teaching methodology.This paper,based on an educational reform project funded by the Hainan Provincial University Education Program,explores how to effectively implement general education on Very Large-Scale Integration(VLSI)design and manufacturing within the Fundamentals of IoT Hardware course.The study conducts practical teaching experiments through innovative instructional models,visualized presentation of semiconductor device structures and processes,integration of industrial-grade simulation tools,and the application of cutting-edge technologies.The objective is to stimulate students’innovative thinking and enhance their hands-on abilities.Finally,this paper summarizes the outcomes of implementing VLSI general education in the course and offers relevant suggestions for further educational reform.展开更多
BACKGROUND Thoracic surgery for radical resection of lung tumor requires deep anesthesia which can lead to an adverse inflammatory response,loss of hemodynamic stability,and decreased immune function.Herein,we evaluat...BACKGROUND Thoracic surgery for radical resection of lung tumor requires deep anesthesia which can lead to an adverse inflammatory response,loss of hemodynamic stability,and decreased immune function.Herein,we evaluated the feasibility and benefits of ultrasound-guided paravertebral nerve block anesthesia,in combination with general anesthesia,for thoracic surgery for lung cancer.The block was performed by diffusion of anesthetic drugs along the paravertebral space to achieve unilateral multi-segment intercostal nerve and dorsal branch nerve block.AIM To evaluate the application of ultrasound-guided paravertebral nerve block anesthesia for lung cancer surgery to inform practice.METHODS The analysis was based on 140 patients who underwent thoracic surgery for lung cancer at our hospital between January 2018 and May 2020.Patients were randomly allocated to the peripheral+general anesthesia(observation)group(n=74)or to the general anesthesia(control)group(n=66).Patients in the observation group received ultrasound-guided paravertebral nerve block anesthesia combined with general anesthesia,with those in the control group receiving an epidural block combined with general anesthesia.Measured outcomes included the operative and anesthesia times,as well as the mean arterial pressure(MAP),heart rate(HR),and blood oxygen saturation(SpO;)measured before surgery,15 min after anesthesia(T1),after intubation,5 min after skin incision,and before extubation(T4).RESULTS The dose of intra-operative use of remifentanil and propofol and the postoperative use of sufentanil was lower in the observation group(1.48±0.43 mg,760.50±92.28 mg,and 72.50±16.62 mg,respectively)than control group(P<0.05).At the four time points of measurement(T1 through T4),MAP and HR values were higher in the observation than control group(MAP,90.20±9.15 mmHg,85.50±7.22 mmHg,88.59±8.15 mmHg,and 90.02±10.02 mmHg,respectively;and HR,72.39±8.22 beats/min,69.03±9.03 beats/min,70.12±8.11 beats/min,and 71.24±9.01 beats/min,respectively;P<0.05).There was no difference in SpO;between the two groups(P>0.05).Postoperative levels of epinephrine,norepinephrine,and dopamine used were significantly lower in the observation than control group(210.20±40.41 pg/mL,230.30±65.58 pg/mL,and 54.49±13.32 pg/mL,respectively;P<0.05).Similarly,the postoperative tumor necrosis factor-αand interleukin-6 levels were lower in the observation(2.43±0.44 pg/mL and 170.03±35.54 pg/mL,respectively)than control group(P<0.05).There was no significant difference in the incidence of adverse reactions between the two groups(P>0.05).CONCLUSION Ultrasound-guided paravertebral nerve block anesthesia improved the stress and hemodynamic response in patients undergoing thoracic surgery for lung cancer,with no increase in the rate of adverse events.展开更多
BACKGROUND Neuroendocrine neoplasms are rarely located in the gallbladder(GB),and carcinoid syndrome is exceedingly rare in patients with GB neuroendocrine neoplasms.CASE SUMMARY We report a case of GB neuroendocrine ...BACKGROUND Neuroendocrine neoplasms are rarely located in the gallbladder(GB),and carcinoid syndrome is exceedingly rare in patients with GB neuroendocrine neoplasms.CASE SUMMARY We report a case of GB neuroendocrine carcinoma(GB-NEC)in a 65-year-old man,who presented with flushing for 2 mo.Pathological specimens of the flushed skin revealed that mucin was deposited between the collagen bundles in the dermis.Computed tomography and magnetic resonance imaging indicated neoplasm in the GB with liver invasion and enlarged lymph nodes in the portacaval space.High fluorodeoxyglucose uptake was detected in lymph nodes in the portacaval space,but distant metastasis was not seen by positron emission tomography.Ultrasound-guided needle biopsy of the GB neoplasm was suggestive of high-grade NEC.Because of the functional characteristics of poorly differentiated NEC,en bloc cholecystectomy,resection of hepatic segments IVb and V,pancreaticoduodenectomy,and regional lymphadenectomy were performed.A diagnosis of poorly differentiated NEC was made by pathological findings and immunohistochemical staining data.Ki-67 index was>80%.The patient refused adjuvant therapy and passed away in the 7th month.CONCLUSION Distinctive manifestation combined with imaging helps make correct preoperative diagnosis.Radical surgery and adjuvant chemotherapy might improve prognosis.展开更多
AIM: To establish a model of retinal neurodegeneration induced by N-Methyl-D-aspartic acid(NMDA) in adult zebrafish.METHODS: We compared the effects of three different NMDA delivery methods on retinal neurodegeneratio...AIM: To establish a model of retinal neurodegeneration induced by N-Methyl-D-aspartic acid(NMDA) in adult zebrafish.METHODS: We compared the effects of three different NMDA delivery methods on retinal neurodegeneration in adult zebrafish: immersion(I.M.), intravitreal injection(I.V.), and intraperitoneal injection(I.P.), and examined retinal pathology and degeneration by hematoxylin and eosin and TUNEL staining in the treated zebrafish. Effects of the NMDA receptor antagonist MK-801 and the natural product resveratrol on NMDA-induced retinal neurodegeneration were also assessed.RESULTS: The thickened inner retina was seen in histology with 100 μmol/L NMDA by I.M. administration. Significant apoptosis in the retinal ganglion cell layer and retinal thickness reduction occurred in 0.5 mol/L NMDA I.P. administration group.Seizure-like behavioral changes, but no retinal histological alteration occurred in 16 mg/kg NMDA I.P. administration group. Resveratrol and MK-801 prevented NMDA-induced retinal neurodegeneration in the zebrafish. CONCLUSION: Among the three drug administration methods, I.V. injection of NMDA is the most suitable for establishment of an acute retinal damage model inzebrafish. I.M. with NMDA is likely the best for use as a chronic retinal damage model. I.P. treatment with NMDA causes brain damage. Resveratrol and MK801 may be a clinically valuable treatment for retinal neurodegeneration.展开更多
Research on the spatial patterns of tree populations is critical for understanding the structure and dynamic processes of forests.However,little is known about how the underlying drivers shape these patterns and speci...Research on the spatial patterns of tree populations is critical for understanding the structure and dynamic processes of forests.However,little is known about how the underlying drivers shape these patterns and species interactions in forest systems.In this study,spatial point pattern analysis investigated the combined eff ects of intraspecifi c interactions and environmental heterogeneity on the spatial structure and internal maintenance mechanisms of Picea crassifolia in the Qilian Mountain National Nature Reserve,China.Data were obtained from a 10.2-ha dynamic monitoring plot(DMP)and sixteen 0.04-ha elevation gradient plots(EGPs).Under complete spatial randomness,both mature trees and saplings in the DMP demonstratedlarge-scale aggregation with negative correlations.In EGPs,saplings were clustered in small mesoscales,mature trees were randomly distributed,and the interactions of saplingstrees at all elevations were not correlated.By eliminating the interference of environmental heterogeneity through the inhomogeneous Poisson process,saplings in the DMP and EGPs were clustered in small scales and trees randomly distributed.Intraspecifi c associations were negatively correlated,in the DMP and at low elevations,and no correlations in high elevations of EGPs.In the vertical scale,saplings showed a small-scale aggregation pattern with increase in elevation,and the aggregation degree fi rst decreased and then increased.The interactions of saplings-trees and saplings–saplings showed inhibitions at small scales,with the degree of inhibition gradually decreasing.Spatial patterns and associations of adults–adults did not change signifi-cantly.The results revealed that intraspecifi c interactions and environmental heterogeneity regulated the spatial patterns of P.crassifolia at small and large scales,respectively.Environmental heterogeneity might be the most decisive factor aff ecting the spatial patterns of saplings,while trees were more aff ected by intraspecifi c interactions.Moreover,competition between trees in this area could be more common than facilitation for the growth and development of individuals.展开更多
In this article, crystalline morphology and molecular orientation of isotactic polypropylene （iPP）, random copolymerized polypropylene （co-PP） and ,β-nucleating agent （β-NA） composites prepared by pressure vib...In this article, crystalline morphology and molecular orientation of isotactic polypropylene （iPP）, random copolymerized polypropylene （co-PP） and ,β-nucleating agent （β-NA） composites prepared by pressure vibration injection molding （PVIM） have been investigated via polarized light microscopy, scanning electron microscopy, wide-angle X-ray diffraction and differential scanning calorimetry. Results demonstrated that the interaction between co-PP and iPP molecular chains was beneficial for the mechanical improvement and the introduction of β-NA further improved the toughness of iPP. In addition, after applying the pressure vibration injection molding （PVIM） technology, the shear layer thickness increased remarkably and the tensile strength improved consequently. Thus, the strength and toughness of iPP/co-PP/β-NA composites prepared by PVIM were simultaneously improved compared to those of the pure iPP prepared by conventional injection molding （CIM）： the impact toughness was increased by five times and tensile strength was increased by 9 MPa. This work provided a new method to further enhance the properties of iPP/co-PP composites through dynamic processing strategy.展开更多
基金supported by the Natural Science Foundation of Beijing Municipality(Grant No.7234401)the Postdoctoral Research Foundation of China(Grant No.88014Y0226)。
文摘Cardiovascular disease(CVD)is often accompanied by chronic kidney disease(CKD)and metabolic disorders such as obesity and type 2 diabetes^([1]).The coexistence of these conditions can lead to systemic dysfunction and substantially increase adverse cardiovascular outcomes.To describe this interplay,the American Heart Association(AHA)recently proposed the concept of cardiovascular-kidney-metabolic(CKM)syndrome^([1]).However,its risk-enhancing factors and underlying mechanisms remain unclear.
基金supported by the Gansu Province Outstanding Youth Fund(No.23JRRA1016)the National Natural Science Foundation of China(Nos.42422102,42071101,41907379)the National Key R&D Program of China(No.2022YFF0801501)。
文摘The response of lake environments in arid Central Asia to climate change during the Late Holocene over the centennial to millennial timescales remains contentious.The reason that primarily paleoenvironmental proxies diverse and the scarcity of accurate quantitative reconstruction records.In this study,we employed diatoms and pollen records from lacustrine sediment in the Aibi Lake of Southwest Junggar Basin to quantitatively reconstruct salinity and watershed precipitation amounts while exploring the associated forcing mechanisms.The results indicate that Aibi Lake salinity varied between 2 and 47 g/L during the Late Holocene Period,indicating a generally brackish environment,and corresponding to prevailing Tryblionella granulata diatom in the lake basin.Westerly-dominated annual precipitation varied between 250 and 320 mm during the Late Holocene Period in the basin,exhibiting a generally semi-arid environment and prevailing desert steppe vegetation.The Aibi Lake has a low salinity of average value of~15 g/L and exhibits elevated precipitation(average value of~280 mm)during the periods of the 2900-1990,1570-1140,and 590-120 cal yr BP.The reconstructed precipitation and salinity exhibit a periodicity of~200 years,which is consistent with the cycle of phase changes of the North Atlantic oscillation(NAO)and total solar irradiance(TSI).This correlation suggests that variations in NOA and TSI significantly influence the precipitation and salinity changes in Central Asia over centennial to millennial timescales.
基金The 2025 Research Project on Party Building and Ideological and Political Work at Hainan Normal University:“Research on the Path to Enhancing University Counselors’Ideological and Political Work Capabilities through Artificial Intelligence Empowerment”(2025DJ(YB)006)。
文摘With the continuous penetration of artificial intelligence(AI)in higher education,the organizational mechanisms and implementation logic of ideological and political education are undergoing new evolutionary trends.These technologies have been widely embedded in key aspects such as teaching management,student services,and value guidance,playing an increasingly prominent role in student status recognition,precise information distribution,and dynamic behavioral interventions.In the practice of ideological and political education in universities,intelligent systems have had a profound impact on the way educational content is supplied and the modes of interaction,shifting the approach from being experience-driven to data-guided.Meanwhile,the task structure of university education scenarios has become more complex,with highly heterogeneous student behaviors,value orientations,and demand preferences,leading to significant challenges for traditional ideological education models in terms of response efficiency and intervention accuracy.Against this background,this paper,based on the trend of digital evolution in ideological and political work in universities,systematically outlines the logical structure and key pivot points in the process of AI integration.It further proposes a fusion strategy composed of“intelligent perception-collaborative services-data-driven”to provide theoretical support and practical pathways for the intelligent transformation of the education system in the new era.
基金supported by the Education Department of Hainan Province(Hnjg2019-50)the Innovation Platform for Academicians of Hainan Province(YSPTZX202036).
文摘With the rapid development of IoT technology,the Fundamentals of IoT Hardware course—one of the core subjects in university IoT programs—urgently requires innovation and improvement in both its content and teaching methodology.This paper,based on an educational reform project funded by the Hainan Provincial University Education Program,explores how to effectively implement general education on Very Large-Scale Integration(VLSI)design and manufacturing within the Fundamentals of IoT Hardware course.The study conducts practical teaching experiments through innovative instructional models,visualized presentation of semiconductor device structures and processes,integration of industrial-grade simulation tools,and the application of cutting-edge technologies.The objective is to stimulate students’innovative thinking and enhance their hands-on abilities.Finally,this paper summarizes the outcomes of implementing VLSI general education in the course and offers relevant suggestions for further educational reform.
文摘BACKGROUND Thoracic surgery for radical resection of lung tumor requires deep anesthesia which can lead to an adverse inflammatory response,loss of hemodynamic stability,and decreased immune function.Herein,we evaluated the feasibility and benefits of ultrasound-guided paravertebral nerve block anesthesia,in combination with general anesthesia,for thoracic surgery for lung cancer.The block was performed by diffusion of anesthetic drugs along the paravertebral space to achieve unilateral multi-segment intercostal nerve and dorsal branch nerve block.AIM To evaluate the application of ultrasound-guided paravertebral nerve block anesthesia for lung cancer surgery to inform practice.METHODS The analysis was based on 140 patients who underwent thoracic surgery for lung cancer at our hospital between January 2018 and May 2020.Patients were randomly allocated to the peripheral+general anesthesia(observation)group(n=74)or to the general anesthesia(control)group(n=66).Patients in the observation group received ultrasound-guided paravertebral nerve block anesthesia combined with general anesthesia,with those in the control group receiving an epidural block combined with general anesthesia.Measured outcomes included the operative and anesthesia times,as well as the mean arterial pressure(MAP),heart rate(HR),and blood oxygen saturation(SpO;)measured before surgery,15 min after anesthesia(T1),after intubation,5 min after skin incision,and before extubation(T4).RESULTS The dose of intra-operative use of remifentanil and propofol and the postoperative use of sufentanil was lower in the observation group(1.48±0.43 mg,760.50±92.28 mg,and 72.50±16.62 mg,respectively)than control group(P<0.05).At the four time points of measurement(T1 through T4),MAP and HR values were higher in the observation than control group(MAP,90.20±9.15 mmHg,85.50±7.22 mmHg,88.59±8.15 mmHg,and 90.02±10.02 mmHg,respectively;and HR,72.39±8.22 beats/min,69.03±9.03 beats/min,70.12±8.11 beats/min,and 71.24±9.01 beats/min,respectively;P<0.05).There was no difference in SpO;between the two groups(P>0.05).Postoperative levels of epinephrine,norepinephrine,and dopamine used were significantly lower in the observation than control group(210.20±40.41 pg/mL,230.30±65.58 pg/mL,and 54.49±13.32 pg/mL,respectively;P<0.05).Similarly,the postoperative tumor necrosis factor-αand interleukin-6 levels were lower in the observation(2.43±0.44 pg/mL and 170.03±35.54 pg/mL,respectively)than control group(P<0.05).There was no significant difference in the incidence of adverse reactions between the two groups(P>0.05).CONCLUSION Ultrasound-guided paravertebral nerve block anesthesia improved the stress and hemodynamic response in patients undergoing thoracic surgery for lung cancer,with no increase in the rate of adverse events.
基金Supported by The National Natural Science Foundation of China,No.81572975Key Research and Development Project of Science and Technology Department of Zhejiang,China,No.2015C03053
文摘BACKGROUND Neuroendocrine neoplasms are rarely located in the gallbladder(GB),and carcinoid syndrome is exceedingly rare in patients with GB neuroendocrine neoplasms.CASE SUMMARY We report a case of GB neuroendocrine carcinoma(GB-NEC)in a 65-year-old man,who presented with flushing for 2 mo.Pathological specimens of the flushed skin revealed that mucin was deposited between the collagen bundles in the dermis.Computed tomography and magnetic resonance imaging indicated neoplasm in the GB with liver invasion and enlarged lymph nodes in the portacaval space.High fluorodeoxyglucose uptake was detected in lymph nodes in the portacaval space,but distant metastasis was not seen by positron emission tomography.Ultrasound-guided needle biopsy of the GB neoplasm was suggestive of high-grade NEC.Because of the functional characteristics of poorly differentiated NEC,en bloc cholecystectomy,resection of hepatic segments IVb and V,pancreaticoduodenectomy,and regional lymphadenectomy were performed.A diagnosis of poorly differentiated NEC was made by pathological findings and immunohistochemical staining data.Ki-67 index was>80%.The patient refused adjuvant therapy and passed away in the 7th month.CONCLUSION Distinctive manifestation combined with imaging helps make correct preoperative diagnosis.Radical surgery and adjuvant chemotherapy might improve prognosis.
基金Supported by the National Natural Science Foundation of China (No.81271425 No.81260148+5 种基金 No.31400988 No.81160144 No.31171044)the Jiangxi Provincial Natural Science Foundation (No.20181ACG70010)the Natural Science Foundation of Jiangxi (No.20151BBG70243 No.20122BCB23007)
文摘AIM: To establish a model of retinal neurodegeneration induced by N-Methyl-D-aspartic acid(NMDA) in adult zebrafish.METHODS: We compared the effects of three different NMDA delivery methods on retinal neurodegeneration in adult zebrafish: immersion(I.M.), intravitreal injection(I.V.), and intraperitoneal injection(I.P.), and examined retinal pathology and degeneration by hematoxylin and eosin and TUNEL staining in the treated zebrafish. Effects of the NMDA receptor antagonist MK-801 and the natural product resveratrol on NMDA-induced retinal neurodegeneration were also assessed.RESULTS: The thickened inner retina was seen in histology with 100 μmol/L NMDA by I.M. administration. Significant apoptosis in the retinal ganglion cell layer and retinal thickness reduction occurred in 0.5 mol/L NMDA I.P. administration group.Seizure-like behavioral changes, but no retinal histological alteration occurred in 16 mg/kg NMDA I.P. administration group. Resveratrol and MK-801 prevented NMDA-induced retinal neurodegeneration in the zebrafish. CONCLUSION: Among the three drug administration methods, I.V. injection of NMDA is the most suitable for establishment of an acute retinal damage model inzebrafish. I.M. with NMDA is likely the best for use as a chronic retinal damage model. I.P. treatment with NMDA causes brain damage. Resveratrol and MK801 may be a clinically valuable treatment for retinal neurodegeneration.
基金supported by the National Natural Science Foundation of China(No.32060247)the Central Guidance on Local Science and Technology Development Fund of Gansu Province(No.22ZY2QG001).
文摘Research on the spatial patterns of tree populations is critical for understanding the structure and dynamic processes of forests.However,little is known about how the underlying drivers shape these patterns and species interactions in forest systems.In this study,spatial point pattern analysis investigated the combined eff ects of intraspecifi c interactions and environmental heterogeneity on the spatial structure and internal maintenance mechanisms of Picea crassifolia in the Qilian Mountain National Nature Reserve,China.Data were obtained from a 10.2-ha dynamic monitoring plot(DMP)and sixteen 0.04-ha elevation gradient plots(EGPs).Under complete spatial randomness,both mature trees and saplings in the DMP demonstratedlarge-scale aggregation with negative correlations.In EGPs,saplings were clustered in small mesoscales,mature trees were randomly distributed,and the interactions of saplingstrees at all elevations were not correlated.By eliminating the interference of environmental heterogeneity through the inhomogeneous Poisson process,saplings in the DMP and EGPs were clustered in small scales and trees randomly distributed.Intraspecifi c associations were negatively correlated,in the DMP and at low elevations,and no correlations in high elevations of EGPs.In the vertical scale,saplings showed a small-scale aggregation pattern with increase in elevation,and the aggregation degree fi rst decreased and then increased.The interactions of saplings-trees and saplings–saplings showed inhibitions at small scales,with the degree of inhibition gradually decreasing.Spatial patterns and associations of adults–adults did not change signifi-cantly.The results revealed that intraspecifi c interactions and environmental heterogeneity regulated the spatial patterns of P.crassifolia at small and large scales,respectively.Environmental heterogeneity might be the most decisive factor aff ecting the spatial patterns of saplings,while trees were more aff ected by intraspecifi c interactions.Moreover,competition between trees in this area could be more common than facilitation for the growth and development of individuals.
文摘In this article, crystalline morphology and molecular orientation of isotactic polypropylene （iPP）, random copolymerized polypropylene （co-PP） and ,β-nucleating agent （β-NA） composites prepared by pressure vibration injection molding （PVIM） have been investigated via polarized light microscopy, scanning electron microscopy, wide-angle X-ray diffraction and differential scanning calorimetry. Results demonstrated that the interaction between co-PP and iPP molecular chains was beneficial for the mechanical improvement and the introduction of β-NA further improved the toughness of iPP. In addition, after applying the pressure vibration injection molding （PVIM） technology, the shear layer thickness increased remarkably and the tensile strength improved consequently. Thus, the strength and toughness of iPP/co-PP/β-NA composites prepared by PVIM were simultaneously improved compared to those of the pure iPP prepared by conventional injection molding （CIM）： the impact toughness was increased by five times and tensile strength was increased by 9 MPa. This work provided a new method to further enhance the properties of iPP/co-PP composites through dynamic processing strategy.
