Picosecond Laser Surface Texturing of a Stavax Steel Substrate for Wettability Control

In this investigation,a picosecond laser was employed to fabricate surface textures on a Stavax steel substrate,which is a key material for mold fabrication in the manufacturing of various polymer products.Three main types of surface textures were fabricated on a Stavax steel substrate:periodic ripples,a two-scale hierarchical two-dimensional array of micro-bumps,and a micro-pits array with nanoripples.The wettability of the laser-textured Stavax steel surface was converted from its original hydrophilicity into hydrophobicity and even super-hydrophobicity after exposure to air.The results clearly show that this super-hydrophobicity is mainly due to the surface textures.The ultrafast laserinduced catalytic effect may play a secondary role in modifying the surface chemistry so as to lower the surface energy.The laser-induced surface textures on the metal mold substrates were then replicated onto polypropylene substrates via the polymer injection molding process.The surface wettability of the molded polypropylene was found to be changed from the original hydrophilicity to superhydrophobicity.This developed process holds the potential to improve the performance of fabricated plastic products in terms of wettability control and easy cleaning.

Temporal patterns of three sympatric pheasant species in the Nanling Mountains: N-mixture modeling applied to detect abundance

Background:The reliability of long-term population estimates is crucial for conservation and management purposes.Most previous studies assume that count indices are proportionally related to abundance;however,this assumption may not hold when detection varies spatially and temporally.We examined seasonal variations in abundance of three bird species(Cabot’s Tragopan Tragopan caboti,Silver Pheasant Lophura nycthemera,and Whitenecklaced Partridge Arborophila gingica) along an elevational gradient,using N-mixture models that take into account imperfect detection in our bird data.Methods:Camera-trapping was used to monitor temporal activity patterns of these species at Guangdong Nanling National Nature Reserve from December 2013 to November 2017(4 seasons per year).For abundance analysis(N-mixture modeling),we divided a year into 4 seasons,i.e.3 months per season,and performed the analysis by season.Elevation was incorporated into the N-mixture model as a covariate that may affect abundance.We compared the N-mixture model with a null model(no covariate model) and selected the better model based on AIC values to make an inference.Results:From 24 sampling sites,we obtained 6786 photographs of 8482 individuals of 44 bird species and 26 mammal species.Silver Pheasant was photographed much more frequently and showed higher temporal activity frequency than White-necklaced Partridge or Cabot’s Tragopan.Silver Pheasant was camera-captured most frequently in summer,and other two species in winters.All three species had two daytime activity peaks:between 6:00 a.m.and 10:00 a.m.,and between 5:00 p.m.and 7:00 p.m.,respectively.Our estimated abundance and detection probability from the N-mixture model were variable by season.In particular,all three species showed greater abundance in summer than in winter,and estimated abundance patterns of all three species were more similar with observed cameratrapping counts in summers.Moreover,in winter,elevation had a positive impact on abundance of Silver Pheasant and Cabot’s Tragopan,but not on White-necklaced Partridge.Conclusions:Our results demonstrate that the N-mixture model performed well in the estimation of temporal popu lation abundance at local fixed permanent plots in mountain habitat in southern China,based on the modeling of repeated camera-trapping counts.The seasonal differences in abundance of the three endemic bird species and the strong effect of elevation on abundance of two species in winter were only indicative of variations in spatio-tempora distribution within species and between species.In identifying suitable habitat for endemic pheasants,the positive elevational effect also suggests that more attention should be paid to conservation of areas with higher elevation in the Nanling Mountains.

基于红外相机监测的广东南岭国家级自然保护区鸟兽多样性及其垂直分布特征

生物多样性的海拔格局一直是生态学、生物地理学和保护生物学研究的核心问题之一。本研究利用红外相机对广东南岭国家级自然保护区完整垂直带的兽类和鸟类开展连续10年的野外监测,分析了保护区当前鸟兽多样性及受胁情况,并通过整合水平与垂直分布的多样性格局开展热点与空缺分析。2012–2021年间共设置了116个红外相机点位,相机累计拍摄85,164个工作日,获得可识别独立有效照片21,194张,共记录到兽类24种,鸟类50种。兽类受威胁物种比例较高,为45.83%。相对多度指数(relative abundance index,RAI)最高的5种兽类为赤麂(Muntiacus vaginalis)、小麂(M.reevesi)、红腿长吻松鼠(Dremomys pyrrhomerus)、鼬獾(Melogale moschata)和藏酋猴(Macaca thibetana);而红颊獴(Herpestes javanicus)和水鹿(Rusa unicolor)RAI最低,仅各拍摄到1次。RAI最高的4种鸟类是白鹇(Lophuranycthemera)、紫啸鸫(Myophonuscaeruleus)、黄腹角雉(Tragopan caboti)和白眉山鹧鸪(Arborophila gingica),有42种鸟类的RAI指数小于1,主要来自雀形目、鴷形目和鸮形目。广义加性模型结果表明,兽类和鸟类的物种丰富度与海拔显著相关,呈典型的“中峰格局”,中海拔(1,000–1,400 m)物种丰富度较高。β多样性分析表明低海拔和高海拔与其他海拔段之间的分类相异性最高,中海拔段之间的相异性相对较小。热点与空缺分析表明,广东南岭国家级自然保护区兽类和鸟类主要集中分布在3个热点地区,且全部分布于中高海拔;同时部分区域具有较高的鸟兽多样性,但并未包含在保护区范围内。总体看来,当下广东南岭国家级自然保护区野生动物仍面临较为严峻的保护压力。在南岭国家公园建设大背景下,我们建议当地管理部门:(1)以物种为单元,针对重点物种制定保护管理政策,特别是大中型兽类;(2)充分重视保护区中高海拔地段的生境管理,维持区内完整的气候与生物垂直带谱;(3)建立多营养级生物多样性监测网络,关注人为干扰、环境因子、功能特征、种间互作网络和进化历史等综合因素对野生动物分布格局的长期影响。

红外相机技术与其他几种森林鸟类多样性调查方法的比较

为了探讨红外相机技术、网捕法、固定距离样线法和固定半径样点法对森林鸟类多样性调查的有效性和实用性,我们于2011–2016年,用这几种方法调查了广东南岭国家级自然保护区和车八岭国家级自然保护区的鸟类多样性。在南岭,固定距离样线法和固定半径样点法记录鸟类222种,网捕鸟类43种,红外相机拍到鸟类47种;其中1种鸟仅网捕到,6种鸟仅被红外相机拍到,164种鸟仅被固定距离样线法和固定半径样点法记录到。在车八岭,固定距离样线法和固定半径样点法记录鸟类109种,网捕鸟类42种,红外相机拍到鸟类27种,其中9种鸟仅网捕到,3种鸟仅被红外相机拍到,97种鸟仅被固定距离样线法和固定半径样点法记录到。随着鸟类的体重、体长、翅长和跗蹠增加,网捕到的鸟类个体数量减少,鸟类身体大小与网捕到的鸟类数量呈显著负相关;而红外相机拍到的鸟类数量随鸟类的身体大小增大而增加,并且呈显著的正相关。本文的结果显示,网捕法和红外相机技术针对不同类群的鸟类调查效力不同,但都是固定距离样线法和固定半径样点法的有效补充。建议今后开展森林鸟类多样性调查与监测时,尽量采用多种研究方法相结合,以求达到最优的效果。

Femtosecond laser-induced surface wettability modification of polystyrene surface

In this paper, we demonstrated a simple method to create either a hydrophilic or hydrophobic surface. With femtosecond laser irradiation at different laser parameters, the water contact angle (WCA) on polystyrene’s surface can be modified to either 12.7° or 156.2° from its original WCA of 88.2°. With properly spaced micro-pits created, the surface became hydrophilic probably due to the spread of the water droplets into the micro-pits. While with properly spaced micro-grooves created, the surface became rough and more hydrophobic. We investigated the effect of laser parameters on WCAs and analyzed the laser-treated surface roughness, profiles and chemical bonds by surface profilometer, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). For the laser-treated surface with low roughness, the polar (such as C—O, C=O, and O—C=O bonds) and non-polar (such as C—C or C—H bonds) groups were found to be responsible for the wettability changes. While for a rough surface, the surface roughness or the surface topography structure played a more significant role in the changes of the surface WCA. The mechanisms involved in the laser surface wettability modification process were discussed.

PMMA-Based Microsphere Mask for Sub-wavelength Photolithography

The authors present a polymethyl methacrylate(PMMA)-based,reusable microsphere mask used in the laser sub-wavelength photolithography.In order to overcome the diffraction limit to achieve nano-structuring using l-|im laser wavelength,the photolithography technique was conventionally characterized by applying a one-off monolayer of silica microspheres serving as Mie scatterers.Addressing the major limitation of this technique,which was that the monolayer of microspheres must be prepared on the sample surface prior to fabrication,the proposed hot press approach could firmly fuse the 1silica microspheres to the PMMA base without the use of adhesives.The PMMA-based microsphere mask could hence reduce the amount of work for the monolayer preparation and was proven reusable for at least 20 times without damage to top or bottom surfaces.Using the mask,dimples that were 0.7 pm in diameter and 40 nm in depth were produced on tool steel by a single pulse of picosecond laser irradiation.

Empirical study on journal literature guarantee of academic library: A case study of Wuhan University

The rising acceptance of e-only policy and open access initiative transforms the collection composition in academic libraries. Accordingly, the roles of electronic, print and open access journals as part of a library’s journal holdings have become different from the past, which needs to be brought to the forefront. Samples of this research are drawn from the articles whose first author is from Wuhan University. They should be issued in 2013 and indexed by SCIE, SSCI or A&HCI. The authors introduced an improved citation checking method to the study by matching the journal cited references of the sample with the journals from print, electronic collections and the world’s major open access databases that are available at the Wuhan University Library in accordance with the publishing year instead of the volume number. Thus, the availability and unavailability of the source journals in open access, electronic, and print journal resources can be examined and compared in a comprehensive manner. By comparing the effectiveness of these three formats of resources as the reference source of published articles, this article attempts to analyze their features and tendencies under the current open access environment as well as discusses how the development of open access journals has impacted the collection building of university libraries in China, so as to provide enlightenment and reference for academic libraries to optimize their resource provision and meet the patrons’ current needs.