Strengthening and weakening of methane hydrate by water vacancies

Gas clathrate hydrates show promising applications in sustainable technologies such as future energy resources, gas capture and storage. The stability of clathrate hydrates under external load is of great crucial to those important applications, but remains unknown. Water vacancy is a common structural defect in clathrate hydrates. Herein, the mechanical characteristics of sI methane hydrates containing three types of water vacancy are investigated by molecular dynamics simulations with four different water forcefields. Mechanical properties of methane hydrates such as tensile strength are dictated not only by the density but also the type of water vacancy. Surprisingly, the tensile strength of methane hydrates can be weakened or strengthened, depending on the adopted water model and water vacancy density. Strength enhancement mainly results from the formation of new water cages. This work provides critical insights into the mechanics and microstructural properties of methane clathrate hydrates under external load, which is of primary importance in the recovery of natural gas from methane hydrate reservoirs.Cited as: Lin, Y., Liu, Y., Xu, K., Li, T., Zhang, Z., Wu, J. Strengthening and weakening of methane hydrate by water vacancies. Advances in Geo-Energy Research, 2022, 6(1): 23-37. https://doi.org/10.46690/ager.2022.01.0

The Association and Clinical Significance of CDKN2A Promoter Methylation in Head and Neck Squamous Cell Carcinoma: a Meta-Analysis

Background/Aims: The association between cyclin-dependent kinase inhibitor 2A (CDKN2A) hypermethylation and head and neck squamous cell carcinoma (HNSCC) risk has been investigated by a number of studies. However, these studies have not demonstrated consistent results. Moreover, the role of CDKN2A methylation in HNSCC carcinogenesis and its clinical significance remain unclear. Methods: We performed a systematic meta-analysis based on 72 articles (including 3399 HNSCCs, 668 premalignant lesions, and 2393 normal controls) from the PubMed, Google Scholar, Web of Science, Embase, China National Knowledge Infrastructure and Wanfang databases. Results: Our study showed a significant increase in the frequency of CDKN2A methylation during HNSCC carcinogenesis (HNSCC vs. normal controls, odds ratio (OR) = 6.72, P < 0.01; HNSCC vs. precancerous lesions, OR = 1.89, P < 0.05; precancerous lesions vs. normal controls, OR = 14.70, P < 0.01). Moreover, CDKN2A methylation was significantly associated with gender (OR = 1.34; P < 0.05) and lymph node metastasis (OR = 2.32; P < 0.01). The area under summary receiver operating characteristic curve (AUC) for diagnosis of HNSCC based on all samples and saliva sample subgroup were 0.77 and 0.96, respectively. Additionally, CDKN2A hypermethylation was significantly associated with shorter overall survival (OS) (hazard ratio (HR) = 1.01, P < 0.05) and recurrence-free survival (RFS) (HR = 1.77, P < 0.05). Conclusion: Our findings indicate CDKN2A methylation is involved in the carcinogenesis, progression, and metastasis of HNSCC. Furthermore, methylated CDKN2A could be a potential diagnostic and prognostic biomarker for HNSCC

Skeletal Muscle Regeneration on Protein-Grafted and Microchannel-Patterned Scaffold for Hypopharyngeal Tissue Engineering

In the field of tissue engineering, polymeric materials with high biocompatibility like polylactic acid and polyglycolic acid have been widely used for fabricating living constructs. For hypopharynx tissue engineering, skeletal muscle is one important functional part of the whole organ, which assembles the unidirectionally aligned myotubes. In this study, a polyurethane (PU) scaffold with microchannel patterns was used to provide aligning guidance for the seeded human myoblasts. Due to the low hydrophilicity of PU, the scaffold was grafted with silk fibroin (PU-SF) or gelatin (PU-Gel) to improve its cell adhesion properties. Scaffolds were observed to degrade slowly over time, and their mechanical properties and hydrophilicities were improved through the surface grafting. Also, the myoblasts seeded on PU-SF had the higher proliferative rate and better differentiation compared with those on the control or PU-Gel. Our results demonstrate that polyurethane scaffolds seeded with myoblasts hold promise to guide hypopharynx muscle regeneration

Study of brain network alternations in non-lesional epilepsy patients by BOLD-fMRI

ObjectiveTo investigate the changes of brain network in epilepsy patients without intracranial lesions under resting conditions.MethodsTwenty-six non-lesional epileptic patients and 42 normal controls were enrolled for BOLD-fMRI examination. The differences in brain network topological characteristics and functional network connectivity between the epilepsy group and the healthy controls were compared using graph theory analysis and independent component analysis.ResultsThe area under the curve for local efficiency was significantly lower in the epilepsy patients compared with healthy controls, while there were no differences in global indicators. Patients with epilepsy had higher functional connectivity in 4 connected components than healthy controls (orbital superior frontal gyrus and medial superior frontal gyrus, medial superior frontal gyrus and angular gyrus, superior parietal gyrus and paracentral lobule, lingual gyrus, and thalamus). In addition, functional connectivity was enhanced in the default mode network, frontoparietal network, dorsal attention network, sensorimotor network, and auditory network in the epilepsy group.ConclusionThe topological characteristics and functional connectivity of brain networks are changed in in non-lesional epilepsy patients. Abnormal functional connectivity may suggest reduced brain efficiency in epilepsy patients and also may be a compensatory response to brain function early at earlier stages of the disease

Realising advanced risk-based port state control inspection using data-driven Bayesian networks

In the past decades, maritime transportation not only contributes to economic prosperity, but also renders many threats to the industry, causing huge casualties and losses. As a result, various maritime safety measures have been developed, including Port State Control (PSC) inspections. In this paper, we propose a data-driven Bayesian Network (BN) based approach to analyse risk factors influencing PSC inspections, and predict the probability of vessel detention. To do so, inspection data of bulk carriers in seven major European countries from 2005 to 2008 1 in Paris MoU is collected to identify the relevant risk factors. Meanwhile, the network structure is constructed via TAN learning and subsequently validated by sensitivity analysis. The results reveal two conclusions: first, the key risk factors influencing PSC inspections include number of deficiencies, type of inspection, Recognised Organisation (RO) and vessel age. Second, the model exploits a novel way to predict the detention probabilities under different situations, which effectively help port authorities to rationalise their inspection regulations as well as allocation of the resources. Further effort will be made to conduct contrastive analysis between ‘Pre-NIR’ period and ‘Post-NIR’ period to test the impact of NIR started in 2008. © 2018 Elsevier Lt

A risk-based game model for rational inspections in port state control

This paper analyses the game relationship between port authorities and ship owners under the new inspection regime (NIR). Based on 49328 inspection reports from Paris Memorandum of Understanding (MoU) (2015-2017), we present a Bayesian Network (BN) model to determine vessel detention rates after adding company performance as a new indicator in PSC inspection. A strategic game model is formulated by incorporating the BN model outcomes. The optimal inspection rate from the game model can help improve port authority performance in PSC. An empirical study is conducted to illustrate the insights of the results and provide suggestions for port authorities

Application of modern supply chain in 5G scenario

The continuous innovation and development of information technology and information infrastructure has driven the evolution of the supply form, and with the emergence of 5G, a mobile integrated communication system that includes communication access, interconnection, and connectivity of things, it has now evolved to a modern supply chain of the social organization collaborative type. This paper briefly describes the process of supply chain development, examines the role of communication technology in driving supply chain development, discusses the relationship between modern supply chain and social development and the support of 5G for modern supply chain, and illustrates the application of 5G in modern supply chain scenarios by reducing information time lag in market-side scenarios as an example