A generalized deceptive pollination system of Doritis pulcherrima (Aeridinae: Orchidaceae) with non-reconfigured pollinaria

<p>Abstract</p> <p>Background</p> <p>As one of largest angiosperm families, orchids have long fascinated evolutionary biologists with their staggering diversity in floral design and display to promote outcrossing. Two of the most intriguing aspects of orchid pollination that promote cross-pollination are pollinarium reconfiguration (PR) and deceptive pollination. PR and generalized food deception employ virtually antagonistic methods of promoting cross-pollination: PR occurs through delayed pollination, involving the relatively long visitation periods that are typically observed for the pollinators of one flower or inflorescence; conversely, generalized food deception leads to reductions in the visitation periods of pollinators to one flower or inflorescence. Thus, it is logical to hypothesize that PR is unnecessary or PR happens soon in generalized food-deceptive orchids in the promotion of cross-pollination. Using <it>Doritis pulcherrima</it> as a model, the aim of this study was to understand the following: (1) the pollination and breeding system of <it>D. pulcherrima</it>; (2) the morphological interactions between orchids and their pollinators; and (3) whether PR is necessary in the promotion of cross-pollination in <it>D. pulcherrima</it>.</p> <p>Results</p> <p>Our observations indicated that <it>Doritis pulcherrima</it> is pollinated almost exclusively by <it>Amegilla nigritar</it> (Hymenoptera: Apidae) and possesses pollinia that are deposited on the “occiputs” (cervical membranes) of these insects. All of evidences are indicated that <it>D. pulcherrima</it> is a generalized food-deceptive orchid. Our morphometric measurements of the flowers and pollinators show that the heights of the “occiputs” with un-oriented pollinaria were equal to the distances between stigmas and surfaces of the middle lobes, suggesting that pollinarium reconfiguration is not necessary in <it>Doritis pulcherrima</it>.</p> <p>Conclusions</p> <p>Our observation and analyses supported the hypothesis that pollinarium reconfiguration is unnecessary in generalized food-deceptive orchids, such as <it>Doritis pulcherrima</it>, for the promotion of cross-pollination. This conclusion was indirectly supported by the abundance of deceptive orchids that do not exhibit pollinarium reconfiguration. There are two mechanisms (i.e. clone-growing characteristics and a long flowering season) that promote fruit sets in the epiphytic food-deceptive orchids in tropical regions.</p

Comparative Study on Sealing Technology of Gas Drainage Borehole in Soft Coal Seam

This paper discusses four kinds of hole sealing technologies for gas drainage in soft coal seam, which are polyurethane hole sealing, cement mortar hole sealing, full-length screen pipe hole sealing and pipe direct connection technology. Through the observation of negative pressure loss, the sealing effect of four sealing technologies is analyzed, the polyurethane sealing effect is poor, the cement mortar, the full-length screen pipe combined with cement mortar and the direct connection technology of pipe are good; through the observation of gas concentration, the gas drainage effect of four sealing technologies is analyzed, the polyurethane sealing technology is the worst, and the direct connection technology of pipe is the worst. The gas drainage effect is the best; according to the sealing effect and gas drainage effect, the traditional polyurethane and cement mortar sealing technology cannot meet the gas drainage demand of the soft coal seam. In the case of slow drilling deformation, the full-length screen pipe sealing technology can be used. In the case of rapid drilling deformation, the direct connection of pipe sealing technology should be used

2-(2-Nitro­phen­yl)-1,3-dioxan-5-ol

In the title compound, C10H11NO5, the six-membered 1,3-dioxane ring displays a chair conformation, with the hydr­oxy and 2-nitro­phenyl groups in equatorial positions, which minimizes steric hindrance. In the crystal, mol­ecules are linked into chains along the b axis by inter­molecular O—H⋯O hydrogen bonds

Mapping studies on sustainability in the performance measurement of public-private partnership projects : a systematic review

The integration of sustainable practices into infrastructure projects under the auspices of public-private partnerships (PPPs) is vital in the attainment of United Nation’s Sustainable Development Goals (SDGs). Since the inception of the SDGs in 2015, the attention of world has been shift-ing towards more sustainable practices and it is essential that the conventional performance measurement models on PPP projects also adapt to the trend of sustainable practices. Therefore, This study aims at reviewing and operationalising sustainable performance measures for the PPP infrastructure projects. A systematic literature review (SLR) methodology was utilised in this study. The research process began with the search, retrieval and selection of thirty-three (33) journal articles. Thoroughly, the selected articles were contently analysed to form key themes that form the basis of this research’s findings. The outcomes of this review demonstrate twenty-seven (27) most critical sustainable performance criteria of PPP projects such as the lowest project costs, green index, disa-bility-friendly inclusion rate and carbon emission per project among others. Although, the study is limited to few journal articles, it provides theoretical and practical understanding of integration of sustainability in PPPs. Further, it gives a list of relevant research gaps for further studies. This study contributes to the benchmarking and management of sustainable performance assessment of PPP projects

Potential application of blockchain technology for embodied carbon estimating in construction supply chains

Carbon emissions are categorised as Embodied Carbon (EC) occurring in the production phase and Operational Carbon (OC) occurring in the operational phase of buildings. The current focus on producing zero-carbon buildings, emphasises reducing OC and ignores the importance of reducing EC emissions. This study focuses on EC. Methods available in EC estimating currently produce estimates that often do not complement each other. This makes it important to develop a robust and accurate methodology for estimating EC. Blockchain is an emerging technology that has significant potential for transaction processing in supply chains. The construction industry being the second least digitalised industry, the adoption of innovative technologies is predominantly important. This paper explores the potential application of blockchain for accurate estimation of EC in construction supply chains. A detailed literature review and expert interviews revealed that, compared to traditional information systems, blockchain systems could eliminate issues in EC estimating highlighting its potential credible application for EC estimating. Scalability was identified as a feature that was lacking in a blockchain system, however, for EC estimating, its impact was identified as minimal. It will be difficult to generalise the findings of the study due to interview based qualitative methodology adopted in this study along with the fact that blockchain is an emerging and fairly new technology. However, a similar process could be followed by other studies to compare blockchain with traditional information systems, to evaluate the suitability of blockchain technology to develop prototype systems

Review of supply chain based embodied carbon estimating method : a case study based analysis

Carbon estimating plays a vital role in the construction industry. The current focus on introducing zero-carbon construction projects reduces operational carbon, at the expense of Embodied Carbon (EC). However, it is important to reduce overall net carbon emissions. There are various methods to estimate carbon, but the accuracy of these estimates is questionable. This paper reviews a novel methodology, the Supply Chain based Embodied carbon Estimating Method (SCEEM), which was introduced recently to accurately estimate EC in construction supply chains. SCEEM is compared against existing EC estimating methods (Blackbook and eToolLCD) using a case study approach. It is also supplemented with a comprehensive literature review of existing EC methods. The EC values calculated using Blackbook and eToolLCD were mostly higher than SCEEM. Since SCEEM uses actual site data and considers first principles-based value addition method to estimate EC, it is considered accurate. The cross-case analysis revealed that SCEEM provided consistent results. Hence, SCEEM is recommended to accurately estimate EC of any type of project