Generative or Contrastive? Phrase Reconstruction for Better Sentence Representation Learning

Though offering amazing contextualized token-level representations, current pre-trained language models actually take less attention on acquiring sentence-level representation during its self-supervised pre-training. If self-supervised learning can be distinguished into two subcategories, generative and contrastive, then most existing studies show that sentence representation learning may more benefit from the contrastive methods but not the generative methods. However, contrastive learning cannot be well compatible with the common token-level generative self-supervised learning, and does not guarantee good performance on downstream semantic retrieval tasks. Thus, to alleviate such obvious inconveniences, we instead propose a novel generative self-supervised learning objective based on phrase reconstruction. Empirical studies show that our generative learning may yield powerful enough sentence representation and achieve performance in Sentence Textual Similarity (STS) tasks on par with contrastive learning. Further, in terms of unsupervised setting, our generative method outperforms previous state-of-the-art SimCSE on the benchmark of downstream semantic retrieval tasks.Comment: Preprin

Simulation and Experimental Study on Cuttings-Carrying for Reverse Circulation Horizontal Directional Drilling with Dual Drill Pipes

In the past decades, horizontal directional drilling (HDD) has been successfully used to install various pipelines in different strata. However, construction accidents such as drill-burying and drill-sticking occur occasionally when pipelines installed by HDD method in an unstable stratum such as sand cobble stratum. Recently, HDD with dual drill pipes was used to install pipelines in unstable stratum, and the effect is significant. The law of cuttings migration for HDD with dual drill pipes is still unclear. Therefore, it is necessary to study the law of cuttings migration in reverse circulation with dual drill pipes. This study performs numerical simulations and experimental research on the cuttings-carrying process in reverse circulation directional drilling with dual drill pipes. Based on the assumption of dual concentric pipes, simulations of fluid-solid two-phase flows are conducted in different flow channels between the inner and outer drill pipes. An experimental cuttings-carrying model is then established. By combining the results of the numerical simulations and experimental investigation, the hydraulic parameters of the dual drill pipe system are optimized, and the rationalities of the drill tool design and the grading selection are validated. The results of this study provide a reference cuttings-carrying model during reverse circulation HDD with dual drill pipes. Document type: Articl

Activity of bimetallic PdIn/CeO₂ catalysts tuned by thermal reduction for improving methanol synthesis via CO₂ hydrogenation

Synergistic Pd–In2O3 catalysts are promising candidates for producing methanol via CO2 hydrogenation, and the metal phases in them can be tuned by thermal reduction treatment affecting the catalytic activity significantly. This work presents a comprehensive investigation to gain an insight into the effect of thermal reduction temperature on the variation and interaction of Pd and In2O3 phases supported on CeO2 (viz., PdIn/CeO2) and their correlations with CO2 hydrogenation toward methanol synthesis. The findings show that Pd/In-rich PdIn alloys and In2O3 with relatively strong interaction are key phases (by reducing the PdIn/CeO2 at 300°C) for promoting methanol formation, leading to a high selectivity to methanol at 78.9% and space–time yield (STY) of 3.6 gCH3OH gPdIn−1 h−1. A further increase in reduction temperature (from 300 to 500°C) promoted the formation of homogenized PdIn intermetallic alloys with significantly poor ability for H2 dissociation and CO2 activation, and hence poor methanol yield

Studies on sesame regeneration system and oil body induction in cultured sesame cells

近年來，利用植物作為生物工廠生產外源重組蛋白質( recombinant protein)受到相當的重視。油體膜蛋白因能專一表現在植物種子油體(oil body)上，而且可依據油體比水輕的特性，利用簡易的步驟分離及純化外源表現蛋白質，因此是一作為表達外源蛋白質的良好載體(carriers)。胡麻(Sesame)，又稱芝麻，是目前世界栽種的幾種重要油料作物之一，其種子含油量超過50%，是利用油體膜蛋白表現外源蛋白質之極佳目標作物。然而，為了能夠達到實際應用的目的，建立有效的芝麻細胞外源基因表達系統是一必要條件。本研究在探討培養條件對於胡麻癒傷組織之形成、體胚之再生、以及細胞內油體含量變化之影響，以期能達到利用胡麻及其懸浮細胞作為油膜蛋白基因表現系統之目的。實驗結果發現，在不同培養條件下所誘導出之癒傷組織依其型態可分為三類。其中第三類(type III)為擬胚體(embryogenic)之癒傷組織，經挑選後進行再生條件測試發現，在含6% Maltose、1 mg/l NAA、1 mg/l BA之培養條件下，可得到較佳的再生結果。實驗中我們並以不同的鹽類、2,4-D與BA比率、以及各種不同的添加物，測試其對於胡麻癒傷組織及懸浮細胞中油體含量變化的影響，發現胡麻癒傷組織及懸浮細胞中含油量皆隨著培養基中2,4-D濃度之提高而增高。另外，在培養基中添加0.1 mg/ l 或0.2 mg/ l ABA，癒傷組織油含量亦有增加的現象。在比較多種不同胡麻品系癒傷組織細胞內油含量實驗中發現，誘導自各種不同胡麻品系之癒傷組織細胞內油含量經測試後皆在1﹪左右。Plant-based expression systems for the production of recombinant proteins and peptides have been recently received much attention. Oleosin, an unique tissue-specific structural protein expressed in plant seed oil body, has been recognized to be a good carriers for producing foreign proteins. The recombinant proteins carried by oleosins can be easily purified using centrifugation based on the fact that oil-body has lower buoyant density than water. Sesame is one of the important oil seed crops in the world, and its seed possesses more than 50 % oil content in dry weight which makes it a very good candidate as an oil body-based expression system. However, before we can put it into practice, an efficient cell expression system has to be firstly established. This study is to investigate the effects of culture conditions on callus induction from sesame seed, regeneration of plant from somatic embryos, and also on the changes of oil-body content in the cultured cells. According to morphological appearance, the induced calli were classified into three different cell types, i.e. type I, II, and III. The type III callus, which showed embryogenic characteristic, were selected and tested for their regeneration response. The best condition was found to be with 6 % maltose, 1 mg/l NAA, and 1 mg/l BA. We also examined the effects of different salts, 2,4-D vs. BA ratios, and different additives on the oil body content in the callus and the suspension cells. It was found that the oil content in either callus or suspension cells increased with the elevated 2,4-D concentration in the culture medium. Addition of 0.1 mg/l or 0.2 mg/l ABA was found also increase the oil contents in the sesame calli. Comparison of callus induced from various sesame varieties indicated that they all have an average of about 1﹪oil content.目 錄 頁次 中文摘要………………………………………………………… 1 英文摘要………………………………………………………… 3 前言………………………………………………………………… 5 前人研究………………………………………………………….. 6 植物蛋白質表達系統………………………………………….. 6 油體與油體膜蛋白………………………………………….…. 8 油體重組蛋白質表達系統………………………………….…. 10 胡麻簡介……………………………………………………….. 10 芝麻細胞表達系統…………………………………………….. 11 芝麻癒傷組織的誘導與再生系統的建立…………………….. 12 芝麻培養細胞油體的導……………………………………….. 12 材料與方法……………………………………………………….. 14 植物材料……………………………………………………….. 14 植物培養基…………………………………………………….. 14 多株抗體……………………………………………………….. 15 芝麻植株栽培………………………………………………….. 15 芝麻種子表面消毒…………………………………………….. 15 芝麻癒傷組織誘導…………………………………..………… 15 芝麻癒傷組織生長速率測試……………………………..…… 16 芝麻植株再生………………………………………………….. 16 芝麻懸浮細胞培養…………………………………………..… 17 芝麻細胞內油含量測定………………………………..……… 17 培養基成分對芝麻細胞內含油量的影響………………..…… 18 不同添加物對芝麻癒傷組織內含油量的影響……………..… 18 不同添加物對芝麻懸浮細胞細胞內含油量的影響………….. 19 不同品系芝麻癒傷組織細胞內含油量比較………………….. 19 油體之純化…………………………………………………….. 19 芝麻種子與癒傷組織油體組成分比較……………………….. 21 蛋白質樣品處理……………………………………………….. 21 硫酸十二酯納聚丙烯醯胺膠體電泳………………………….. 21 西方墨點法之分析…………………………………………….. 23 結果………………………………………………………………… 25 芝麻植株再生…………………………………………………… 25 芝麻癒傷組織誘導……………………………………………. 25 不同基礎培養基及維他命對Type III癒傷組織誘導形成率 的影響………………………………………………………. 25 芝麻植株栽培…………………………………………………. 26 芝麻癒傷組織植株再生……………………………………….. 27 不同auxin/cytokinin濃度對芝麻癒傷組織再生之影響….. 27 7天黑暗處理，對芝麻再生率的影響……………………….. 27 不同醣類對台南一號癒傷組織再生的影響………………….. 28 不同植物賀爾蒙對台南一號癒傷組織再生的影響………….. 28 芝麻細胞油體誘導……………………………………………… 29 不同2,4-D / BA 濃度比例，對台南一號癒傷組織生長速 率的影響………………………………………………….…. 29 不同基礎培養基，對台南一號癒傷組織細胞內含油量的 影響………………………………………………………….. 29 不同2,4-D / BA 濃度比例，對台南一號癒傷組織細胞內 含油量的影響…………………………………………….…. 30 癒傷組織誘導過程中，加入不同添加物對台南一號癒傷 組織細胞內含油量及細胞乾重的影響…………………….. 30 台南一號懸浮細胞培養……………………………………….. 31 懸浮細胞培養過程中，加入不同添加物對台南一號懸浮細 胞，細胞內含油量的影響… …………………………..…... 31 懸浮細胞培養過程中，加入不同濃度ABA對台南一號懸 浮細胞，細胞內含油量的影響… ………………………..... 32 不同芝麻品系癒傷組織細胞內由含量比較………………..… 33 討論………………………………………………………………… 34 芝麻植株再生………………………………………………….. 34 芝麻細胞油體誘導…………………………………………….. 35 參考文獻…………………………………………………………… 37 圖表………………………………………………………………… 4

Axial Force Calculation Model for Completion String with Multiple Point Resistances in Horizontal Well

Frequent accidents may happen during the string run-down and pull process due to the lack of accuracy in the prediction of string force analysis. In order to precisely predict the completion string axial force in horizontal wells, a new model is established, and an in-house software has been developed. The model aims to predict the multiple local resistances that occur at different points on the completion string, which makes up for the technical defects of the commonly used software. It can calculate resistance at different points of the string, which will lead to varying hook load amplification. This method can also predict the axial force of the completion string. By changing the hook load, location, and direction, the resistance can be determined more accurately. Based on the calculation and analysis, the relationship between local resistance, the blocking point, and the amplification factor is also obtained. Furthermore, this model is used to analyze the local resistance of a horizontal well with multiple external packers in the low-permeability Sadi Reservoir of Halfaya Oilfield, Iraq. The recorded data from in-site operations are compared with the predicted results from this model. The results show that the relative errors between the recorded data and model calculation are within the range of 10%, which indicates that the calculated values are reliable. Meanwhile, the results indicate the success of the subsequent completion design and the construction of the oilfield

An experimental study of liquid unloading in the curve section of horizontal gas wells

Liquid unloading is a very common and important issue in horizontal gas wells, and the presence of curve sections increases the complexity of the phenomenon and its study. Liquid loading in a gas well will sharply reduce production, therefore, the liquid-unloading onset of different curved pipes is essential to gas production. In this work, liquid-unloading onset experiments were conducted in curved pipes with different curvatures. Then, the critical gas velocity VsgCR can be determined according to the measured pressure gradients, liquid holdup, and liquid film reversal. This work analyzes the factors which will lead to the liquid unloading and explores the trend of the pipe curvature’s influence on the liquid unloading under laboratory conditions. The experimental results show that the critical gas velocity rises with the increase of pipe curvature, the increase is mainly due to the centrifugal force. The present work also compares the predicted results of the OLGA model and Beggs–Brill model with experimental data. The comparison results indicate that both models fit relatively well to the experimental data at the low superficial gas velocity, and both models have poor performance at high superficial gas velocity. The OLGA model fits the experimental data better than the Beggs–Brill model at high superficial gas velocity. The error analysis shows that most of the predicted data is not in good agreement with experimental data. Some errors between experimental data and calculation results are out of the range of 50%

GmIAA27 Encodes an AUX/IAA Protein Involved in Dwarfing and Multi-Branching in Soybean

Soybean plant height and branching affect plant architecture and yield potential in soybean. In this study, the mutant dmbn was obtained by treating the cultivar Zhongpin 661 with ethylmethane sulfonate. The dmbn mutant plants were shorter and more branched than the wild type. The genetic analysis showed that the mutant trait was controlled by a semi-dominant gene. The candidate gene was fine-mapped to a 91 kb interval on Chromosome 9 by combining BSA-seq and linkage analysis. Sequence analysis revealed that Glyma.09g193000 encoding an Aux/IAA protein (GmIAA27) was mutated from C to T in the second exon of the coding region, resulting to amino acid substitution of proline to leucine. Overexpression of the mutant type of this gene in Arabidopsis thaliana inhibited apical dominance and promoted lateral branch development. Expression analysis of GmIAA27 and auxin response genes revealed that some GH3 genes were induced. GmIAA27 relies on auxin to interact with TIR1, whereas Gmiaa27 cannot interact with TIR1 owing to the mutation in the degron motif. Identification of this unique gene that controls soybean plant height and branch development provides a basis for investigating the mechanisms regulating soybean plant architecture development