Ontogenetic trait variation and metacommunity effects influence species relative abundances during tree community assembly

Predicting species abundance is one of the most fundamental pursuits of ecology.Combining the information encoded in functional traits and metacommunities provides a new perspective to predict the abundance of species in communities.We applied a community assembly via trait selection model to predict quadrat-scale species abundances using functional trait variation on ontogenetic stages and metacommunity information for over 490 plant species in a subtropical forest and a lowland tropical forest in Yunnan,China.The relative importance of trait-based selection,mass effects,and stochasticity in shaping local species abundances is evaluated using different null models.We found both mass effects and trait selection contribute to local abundance patterns.Trait selection was detectable at all studied spatial scales(0.04e1 ha),with its strength stronger at larger scales and in the subtropical forest.In contrast,the importance of stochasticity decreased with spatial scale.A significant mass effect of the metacommunity was observed at small spatial scales.Our results indicate that tree community assembly is primarily driven by ontogenetic traits and metacommunity effects.Our findings also demonstrate that including ontogenetic trait variation into predictive frameworks allows ecologists to infer ecological mechanisms operating in community assembly at the individual level.

Analysis of the clinical efficacy of two-stage revision surgery in the treatment of periprosthetic joint infection in the knee:A retrospective study

BACKGROUND Periprosthetic joint infection(PJI)is a catastrophic complication that can occur following total knee arthroplasty(TKA).Currently,the treatment for PJI mainly includes the use of antibiotics alone,prosthetic debridement lavage,primary revision,secondary revision,joint fusion,amputation,etc.AIM To explore the clinical effect of two-stage revision surgery for the treatment of PJI after TKA.METHODS The clinical data of 27 patients(3 males and 24 females;age range,47–80 years;mean age,66.7±8.0 years;27 knees)with PJI treated with two-stage revision surgery in our hospital between January 1,2010 and December 31,2020 were analyzed retrospectively.The following outcomes were compared for changes between preoperative and last follow-up results:Erythrocyte sedimentation rate(ESR),C-reactive protein(CRP),visual analogue scale(VAS)scores,Hospital for Special Surgery(HSS)scores,knee range of motion(ROM),and infection cure rates.RESULTS All 27 patients were followed up(range,13–112 mo).The ESR(14.5±6.3 mm/h)and CRP(0.6±0.4 mg/dL)of the patients at the last follow-up were significantly lower than those at admission;the difference was statistically significant(P<0.001).The postoperative VAS score(1.1±0.7),HSS score(82.3±7.1),and knee ROM(108.0°±19.7°)were significantly improved compared with those before the surgery;the difference was statistically significant(P<0.001).Of the 27 patients,26 were cured of the infection,whereas 1 case had an infection recurrence;the infection control rate was 96.3%.CONCLUSION Two-stage revision surgery can effectively relieve pain,control infection,and retain good joint function in the treatment of PJI after TKA.

Effect of rapamycin on POCD induced by anesthesia and its mechanism

Objective:To investigate the effect of rapamycin on cognitive function of Operative Cognitive Dysfunction rats induced by anesthesia and explore its possible mechanism.Methods:Wistar rats were intraperitoneally injected with 70 mg/kg ketamine for 7 days to establish POCD model after anesthesia.The model rats were randomly divided into model group,rapamycin group,everolimus positive group and 3-methyladenine group.The rats in the model group were intraperitoneally injected with the same amount of normal saline,rapamycin group was intraperitoneally injected with 3.5mg/kg rapamycin,everolimus positive group was intraperitoneally injected with 5.0mg/k everolimus,3-methyladenine group was intraperitoneally injected with 3.5mg/kg rapamycin+2.0mg/kg3-methyladenine for 7 days.Morris water maze was used to measure the retention time,the number of times of platform crossing and the latency time of working memory.Ferritin H,ferritin L,S100β,Beclin 1 were determined by ELISA,and P13K,p-Akt,p-mTOR,4EBP1 were determined by Western blot.Results:In rapamycin group,the retention time and the number of crossing platform were significantly higher than those in the model group(t=6.645,P<0.01;t=5.961,P<0.01),and the latency time of working memory was significantly lower than that in the model group(t=3.799,P<0.01);In rapamycin group,ferritin H,ferritin L,S100βwere significantly lower than that in the model group(t=3.248,P<0.01;t=4.137,P<0.01;t=2.915,P<0.01).3-methyladenine group was significantly lower than rapamycin group in the retention time and the number of times of platform penetration(t=5.138,P<0.01;t=4.437,P<0.01),and the latency time of working memory was significantly higher than rapamycin group(t=2.808,P<0.05);Ferritin H,ferritin L and S100βin 3-methyladenine group were significantly higher than those in pamamycin group(t=2.247,P<0.05;t=3.330,P<0.01;t=2.119,P<0.05).In rapamycin group,P13K and p-Akt protein levels did not change,p-mTOR protein and P-4EBP1 expression was down-regulated,after using 3-methyladenine,P-mTOR protein and P-4EBP1 protein was up-regulated.Conclusions:Rapamycin can improve the cognitive function of POCD rats induced by anesthesia,and its mechanism may be related to the activation of mTOR signaling pathway by rapamycin to promote autophagy.

Evaluation and improvement of pearlite microstructure and mechanical properties in 45Cr4NiMoV and 50Cr5NiMoV steels

The microstructure and mechanical properties of pearlite in 45Cr4NiMoV and 50Cr5NiMoV steels were studied and compared.The microstructural characteristics of pearlite of two steels were carefully examined by optical microscopy,scanning electron microscopy and transmission electron microscopy(TEM),and the type,size and relative amount of extracted carbide particles were analyzed by X-ray diffraction and TEM coupled with selected area electron diffraction.The hardness,tensile property,impact and fracture toughness of pearlite of two steels were also evaluated.Besides,the carbide dissolution kinetics of 45Cr4NiMoV and 50Cr5NiMoV steels were clarified.The results indicated that the carbides in 50Cr5NiMoV steel exhibited higher dissolution temperature than those in 45Cr4NiMoV steel,which induced different morphologies of pearlite after eutectoid transformation.Compared to the pearlite with lamellar M_(23)C_(6)carbides in 45Cr4NiMoV steel,the pearlite with the mixture of spheroidized M_(7)C_(3)and lamellar M_(23)C_(6)carbides in 50Cr5NiMoV steel possessed higher impact and plane-strain fracture toughness but lower hardness and strength,because different pearlite morphologies led to different mechanical properties.In order to further improve the comprehensive properties of the steels,the fraction of M_(7)C_(3)for the material with acceptable properties was examined and dissolution kinetic of M_(7)C_(3)was calculated.Therefore,the austenitizing temperature and holding time could be appropriately selected to keep enough undissolved M_(7)C_(3)in the steels.