中国木材功能性改良技术发展方向

本文论述了 2 1世纪中国木材功能性改良技术的发展方向 ,认为木材功能性改良技术应向一剂多功效、环保、高效与长效型、节约木材、扩大应用领域等五个方面发展。要注重研究与应用的结合 ,提高和完善技术 。

Fast image matching algorithm based on affine invariants

Feature-based image matching algorithms play an indispensable role in automatic target recognition （ATR）. In this work, a fast image matching algorithm （FIMA） is proposed which utilizes the geometry feature of extended centroid （EC） to build affine invariants. Based on at-fine invariants of the length ratio of two parallel line segments, FIMA overcomes the invalidation problem of the state-of-the-art algorithms based on affine geometry features, and increases the feature diversity of different targets, thus reducing misjudgment rate during recognizing targets. However, it is found that FIMA suffers from the parallelogram contour problem and the coincidence invalidation. An advanced FIMA is designed to cope with these problems. Experiments prove that the proposed algorithms have better robustness for Gaussian noise, gray-scale change, contrast change, illumination and small three-dimensional rotation. Compared with the latest fast image matching algorithms based on geometry features, FIMA reaches the speedup of approximate 1.75 times. Thus, FIMA would be more suitable for actual ATR applications.

Lanthanide-doped metal-organic frameworks with multicolor mechanoluminescence

Metal-organic frameworks(MOFs)and mechanoluminescent(ML)materials have been considered as two types of promising materials that have their own application fields.It would be amazing to endow one material with the advantages of ML and MOFs,thus broadening their applications.However,there are quite few investigations on this topic,and the ML mechanism in ML-MOFs remains unclear.In this study,we proposed a strategy for developing ML-MOFs by doping lanthanide ions into the non-centrosymmetric SBD([Sr(μ-BDC)(DMF)]∞)MOF,and successfully synthesized a series of lanthanide-doped MOFs Ln-SBD(Ln=Tb,Dy,Sm,Eu)and Tb1-xEux-SBD(x=0.2,0.4,0.6,0.8)with multicolor ML.The lanthanide ions were uniformly distributed in the matrix of the SBD-MOF,and occupied the Sr site.The MLMOFs exhibited intense multicolor ML emissions varying from green to yellow to red by changing the co-doping ratios and species of lanthanide ions.The similar ML and photoluminescence(PL)spectra indicated that the ML emission was assigned to the radiative transition from the excited states to the ground states of lanthanide ions.The radiative transition was induced by the electron bombardment process that originated from the piezoelectric effect of the non-centrosymmetric SBD host.In addition,a pioneering temperature sensing research based on ML was carried out,which is promising for realizing dual-functional detection of stress and temperature without excitation light sources.This study gives a unique insight for developing more versatile and interesting smart materials by combining the versatility of MOF with the ML emission,imparting additional values to both MOF and ML materials.Moreover,this study provides a general rule for selecting MOFs with an acentric structure as the host for ML materials.

Using the response-effect trait framework to disentangle the effects of environmental change on the ecosystem services

Functional traits play a vital role in mediating the responses of ecosystem services to environmental changes and in predicting the functioning of the ecosystem.However,the connection between functional traits and ecosystem services has become increasingly intricate due to climate change and human activities for degraded ecosystems.To investigate this relationship,we selected 27 sampling sites in the Yanhe River Basin of the Chinese Loess Plateau,each containing two types of vegetation ecosystems:natural vegetation and artificial vegetation ecosystems.At each sampling site,we measured ecosystem services and calculated the composition index of community traits.We established a response–effect trait framework that included environmental factors such as climate,elevation and human activities.Our results showed that leaf tissue density(LTD)was the overlapping response and effect trait when responding to climate change.LTD is positively correlated with mean annual temperature and negatively correlated with supporting services.Under the influence of human activities,leaf nitrogen content and leaf dry matter content were carriers of environmental change.Comparing the two vegetation ecosystems,the relationship between functional traits and ecosystem services showed divergent patterns,indicating that human activities increased the uncertainty of the relationship between functional traits and ecosystem services.Trait-based ecology holds promise for enhancing predictions of ecosystem services responses to environmental changes.However,the predictive ability is influenced by the complexity of environmental changes.In conclusion,our study highlights the importance of understanding the complex connection between functional traits and ecosystem services in response to climate changes and human activities.