A bentonite (BT) suspension is extensively used as a water-based drilling fluid (WDF) for well excavation; however, it suffers from insufficient rheology and poor filtration performance at low solid content. Cellulose nanocrystals (CNCs) with nanoscale dimensions, large surface area, high stiffness, and reactive functional groups are promising candidates to improve the rheology and filtration performance of BT-WDFs through surface interactions. Consequently, a fundamental understanding of the surface interaction between CNCs and BT platelets becomes critical. This work aims to reveal the crucial role of surface characteristics of CNCs on their interaction with BT platelets as well as the rheological and filtration performance of CNC/BT-WDFs. Two types of CNCs with distinctive surface characteristics [i.e., carboxylated CNCs (cCNCs) and cationic CNCs (caCNCs)] were rationally prepared and applied as modifiers in BT-WDFs. The cCNCs were shown to attach to the edge surface of BT platelets and acted as "bridges", connecting BT platelets via "edge-to-edge" association. On the contrary, the caCNCs were absorbed to the face surface of BT platelets and acted as "cross-linking agents", stacking numerous layers of BT platelets through "face-to-face" association. These differences led to the distinctive dispersion state of BT platelets and the overall performance of CNC/BT-WDFs. The cCNCs served as more effective rheological and filtration agents in the developed fluids compared with caCNCs, highlighting the importance of surface characteristics of CNCs in the development of low-solidcontent, high-performance CNC/BT-WDFs for well excavation.

OAHG, an integrated resource, aims to establish a comprehensive functional annotation resource for human protein-coding genes (PCGs), miRNAs, and lncRNAs by multi-level ontologies involving Gene Ontology (GO), Disease Ontology (DO), and Human Phenotype Ontology (HPO). Many previous studies have focused on inferring putative properties and biological functions of PCGs and non-coding RNA genes from different perspectives. During the past several decades, a few of databases have been designed to annotate the functions of PCGs, miRNAs, and lncRNAs, respectively. A part of functional descriptions in these databases were mapped to standardize terminologies, such as GO, which could be helpful to do further analysis. Despite these developments, there is no comprehensive resource recording the function of these three important types of genes. The current version of OAHG, release 1.0 (Jun 2016), integrates three ontologies involving GO, DO, and HPO, six gene functional databases and two interaction databases. Currently, OAHG contains 1,434,694 entries involving 16,929 PCGs, 637 miRNAs, 193 lncRNAs, and 24,894 terms of ontologies. During the performance evaluation, OAHG shows the consistencies with existing gene interactions and the structure of ontology. For example, terms with more similar structure could be associated with more associated genes (Pearson correlation γ2 = 0.2428, p < 2.2e–16).

No abstract

Cellulose nanoparticles (CNPs), including cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs), were used as an environmentally friendly and high performance additive in water-based bentonite drilling fluids for minimizing fluid loss and formation damage. The effects of CNP dimension and concentration on the rheological and filtration properties of the fluids were investigated. With half of the bentonite in the fluid replaced by a small fraction of CNPs, the resultant fluids showed excellent shear thinning behavior and the fluids' viscosity, yield point, and gel strength increased with the concentrations of CNPs. The addition of CNPs did not produce a pronounced effect in loss of the fluids under low temperature and low pressure (LTLP) conditions. However, reduced fluid loss and formation damage were observed with use of CNPs at a higher temperature and pressure condition, demonstrating CNP's potentials for high temperature and high pressure well applications. Additionally, CNCs and CNFs functioned differently in the rheological and filtration properties of the fluids, attributed to their distinct morphology and surface functionality, which could be controlled to maximize the performance of the fluids.

No abstract