Gold nanoclusters embedded in antimicrobial keyboard covers: life cycle assessment and environmental sustainability

Gold nanoparticles and nanoclusters can be used in a variety of sectors in different applications. Research on new synthesis methods and procedures for their integration into products is flourishing with positive results. This study focuses on the environmental impacts of synthesising cysteine-capped gold nanoclusters [Au25(Cys)18] and their integration in silicone keyboard covers. The final product presents an antibactericidal activity that could make it suitable for use in hospital wards to tackle the cross-transmission of pathogens. Life cycle assessment (LCA) methodology is used here to analyse and compare the environmental impacts of antimicrobial keyboard covers against current procedures for cleaning keyboards in hospitals using gloves and alcohol wipes (70%). Furthermore, results have been compared with the normalisation factors based on two reference systems: global emissions and carrying-capacity values. Whilst the first reference system indicates the contribution of a production system relative to the global emissions; the latter provides an indication of the absolute environmental sustainability of the system evaluated. This study shows that adopting an antimicrobial keyboard cover results in lower environmental impacts than using gloves and alcohol wipes, almost for all the impact categories considered

Improved Duncan-Chang model for reconstituted hydrate-bearing clayey silt from the South China Sea

The experimental testing and analysis of strength and deformation characteristics of hydrate reservoirs is an integral part of natural gas hydrate exploitation. However, studies so far have failed to deeply explore samples from the South China Sea. Especially, there is a lack of a simple and applicable method to estimate their mechanical behaviors. Thus, based on test data, an improved Duncan-Chang model is established in this paper to characterize the strength and deformation of reconstituted samples with various hydrate saturation and stress states from this area. This model can accurately describe the strain-hardening characteristics, and failure strength is estimated by the improved Drucker-Prager criterion with high fitting accuracy. The initial elastic modulus and failure ratio are given by the proposed empirical models, which are obtained from experimental data and fitting methods. Generally, this model has several advantages including simple structure, favorable performances, and a limited number of model parameters. Therefore, it could be widely used in strength and deformation analysis. This study can support the prevention and control of geological risks during natural gas hydrate exploitation in the South China Sea.Cited as: Dong, L., Wu, N., Zhang, Y., Liao, H., Hu, G. Li, Y. Improved Duncan-Chang model for reconstituted hydrate-bearing clayey silt from the South China Sea. Advances in Geo-Energy Research, 2023, 8(2): 136-140. https://doi.org/10.46690/ager.2023.05.0

Transcriptome analysis reveals the molecular basis of the response to acute hypoxic stress in blood clam Scapharca broughtonii

Hypoxia tolerance and adaptive regulation are important for aquatic animals, especially for species with poor mobility, such as most bivalves. Previous studies have confirmed that the blood clam Scapharca broughtonii has strong hypoxia resistance. However, the molecular mechanism supporting its hypoxic tolerance is still largely limited. To further screen the genes and their potential regulation of hypoxia tolerance, the transcriptome changes of S. broughtonii after acute hypoxic stress were explored by RNA sequencing. In this study, the average value of Q30 is 92.89%, indicating that the quality of sequencing is relatively high. The Unigenes obtained were annotated using four databases, namely Interpo, KEGG, Swisspro and TrEMBL. The annotation rates in these four databases were 71.82%, 75.95%, 92.98%, and 79.26%, respectively. And also, there were 649 DEGs in group B (dissolved oxygen (DO) of 2.5 mg/L) compared with group D (DO of 7.5 mg/L), among which 252 were up-regulated, and 397 were down-regulated. There were 965 DEGs in group A (DO of 0.5 mg/L), 2.5 mg/L, and 7.5 mg/L, compared with group B, among which 530 were up-regulated, and 435 were down-regulated. Meanwhile, there were 2,040 DEGs in group A compared with group D, among which 901 were up-regulated, and 1,139 were down-regulated. The main metabolic-related pathways of KEGG enriched in this study included Insulin secretion, Insulin signaling pathway, MAPK signal transduction pathway, and PPAR signaling pathway. These pathways may be critical metabolic pathways to solve energy demand and rebuild energy balance in S. broughtonii under hypoxic conditions. This study preliminarily clarified the response of S. broughtonii to hypoxia stress on the molecular levels, providing a reference for the following study on the response laws of related genes and pathways under environmental stress of S. broughtonii

Three step synthesis of benzylacetone and 4-(4-methoxyphenyl)butan-2-one in flow using micropacked bed reactors

The synthesis of benzylacetone from benzyl alcohol and of 4-(4-methoxyphenyl)butan-2-one from 4-methoxybenzyl alcohol, which were previously performed in a batch cascade, were successfully performed in a telescoped flow system consisting of three micropacked bed reactors and a tube-in-tube membrane to remove oxygen. The system consisted of approximately 10 mg of 1 wt% AuPd/TiO2 catalyst for oxidation, 150-250 mg of anatase TiO2 for C-C coupling and 10 mg of 1 wt% Pt/TiO2 for reduction, operating at 115 °C, 130 °C and 120 °C respectively. Oxygen and hydrogen flowrates were 2 and 1.5 NmL/min and alcohol solution inlet flowrates were 10-80 µL/min, while the system operated at a back pressure of 5 barg. This system achieved significantly increased yields of benzylacetone compared to the batch cascade (56% compared to 8%) and slightly increased yields of 4-(4-methoxyphenyl)butan-2-one (48% compared to 41% when using the same catalyst supports). The major advantage of the telescoped flow system was the ability to separate the three reactions, so that each reaction could have its own catalyst and operating conditions, which led to significant process intensification

Slurry loop tubular membrane reactor for the catalysed aerobic oxidation of benzyl alcohol

A novel reactor that combines a catalyst slurry flowing inside a loop configuration, incorporating a tubular membrane (Teflon AF-2400) for controlled oxygen delivery was designed and employed for the aerobic oxidation of benzyl alcohol using a 1 wt% Au-Pd/TiO2 powdered catalyst. This reactor keeps the liquid phase saturated with oxygen, while avoiding the creation of bubbles in it, thus enhancing operation safety. Experimental results in batch mode compared with those of a conventional autoclave demonstrated that the slurry loop membrane reactor reached a similar oxidation turnover frequency (20,000–25,000 h−1) with comparable values of benzaldehyde selectivity (∼70%). Continuous operation was achieved by using a crossflow filter connected to the loop to keep the catalyst from exiting the reactor. Using a 60 cm long tubular membrane, with the slurry flow circulating at 10 mL/min, continuous reaction was performed at 100–120 °C, 0–5 bar oxygen pressure and 1.2–5.0 g/L catalyst loading. Selectivity to benzaldehyde increased by either decreasing the reaction temperature or increasing the external oxygen pressure. The oxygen consumption rate decreased linearly with the catalyst loading, suggesting negligible gas-liquid mass transfer resistance. This was further evidenced by doubling the length of the tubular membrane, which had no effect on the oxidation turnover frequency. The slurry loop membrane reactor showed significantly better performance than packed-bed membrane microchannel reactors, and similar performance as that of a trickle-bed capillary reactor. This reactor can be implemented for a wide range of applications, which rely on the use of powder catalyst, are limited by gaseous reactant availability and require safe operation

Study on the Contribution of Compressor noise to Refrigerator Overall Noise

Recently, greater attention is being paid to refrigerator noise. As we know, compressor is an important part of refrigerator, and it\u27s also a very important noise soure. Based on comparison between compressor noise spectrum and refrigerator noise spectrum, the contributions of compressor noise to the refrigerator overall noise are discussed. Besides compressor direct radiation noise, compressor pressure pulsation and vibration also make great influence on refrigerator noise. A suction and discharge pressure pulsations test bench was built, and then the compressor pressure pulsation data were tested. By compressor suction and discharge pipelines optimization, the pressure pulsations and refrigerator noise were reduced. Vibration transmission path from compressor to refrigerator was investigated, and resonance frequencies on the vibration transmission path were identified. By refrigerator connection pipe optimization, refrigerator noise was reduced

A novel scheme for domain-transfer problem in the context of sentiment analysis

In this work, we attempt to tackle domain-transfer problem by combining old-domain labeled examples with new-domain unlabeled ones. The basic idea is to use old-domain-trained classifier to label some informative unlabeled examples in new domain, and retrain the base classifier over these selected examples. The experimental results demonstrate that proposed scheme can significantly boost the accuracy of the base sentiment classifier on new domain