Multi‐Scale Microstructural Thermoelectric Materials: Transport Behavior, Non‐Equilibrium Preparation, and Applications

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137226/1/adma201602013_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137226/2/adma201602013.pd

Sputtering and amorphization of crystalline semiconductors by Nanodroplet Bombardment

In this review we expose how Nanodroplet Bombardment of surfaces by charged particles produced through electrospray atomization offers unparalleled opportunities for surface engineering of chemically inert crystalline materials. The sputtering yields and rates are comparable or higher than reactive etching techniques and significantly higher than other physical sputtering systems. Moreover, bombardment can amorphatize a thin layer of the target. The imposed physical characteristics of the electrospray, droplet diameter, molecular mass of the spray, and kinetic energy will determine the sputtering and amorphization efficiency, and the topography of the processed target. Molecular dynamics studies have clarified the mechanisms of both processes; amorphous layers appear due to ultra‐fast quenching of melted target pools around the impact area while sputtering is driven by a combination of collision cascades, thermal evaporation, and, for large and fast projectiles, of hydrodynamic forces

Molecular dynamics simulations guided the preparation of nano-silica/polyimide/cellulose composite insulating paper

Following the surge in power loads and continuous improvement in the voltage level, insulating papers' mechanical and electrical properties face new challenges. However, traditional inefficient “tentative” trial and error experiments are formidable to rapidly and efficiently prepare cellulose composite insulating paper because the direct scientific theory or simulation guidance is insufficient. To solve this problem, the nano-silica(nano-SiO2)/polyimide(PI)/cellulose composite models were designed and their mechanical, and dielectric properties were predicted by molecular dynamics (MD) simulation. The preparation of corresponding nano-SiO2/PI/cellulose insulating paper was guided by the MD simulation results and their surface morphology, mechanical properties, and electrical properties were investigated. The experimental results are in good agreement with the MD simulation results and confirmed that P3 insulating paper possesses the best comprehensive performance, and its tensile strength, relative permittivity, dielectric loss, volume resistivity, and breakdown strength are 71.44 MPa, 2.39, 0.2%, 5.16 × 1015 Ω∙m, and 75.8 kV∙mm−1, respectively. This work proves the feasibility and effectiveness of using MD simulation to guide the development of new insulating papers, and compared with the existing traditional preparation methods, this method is expected to be applied to study various new materials in the future and promote the vigorous development of new materials

Study on Micro Interfacial Charge Motion of Polyethylene Nanocomposite Based on Electrostatic Force Microscope

The interface area of nano-dielectric is generally considered to play an important role in improving dielectric properties, especially in suppressing space charge. In order to study the role of interface area on a microscopic scale, the natural charge and injected charge movement and diffusion on the surface of pure LDPE and SiO2/LDPE nanocomposite were observed and studied by gradual discharge under electrostatic force microscope (EFM). It was detected that the charge in SiO2/LDPE nanocomposite moved towards the interface area and was captured, which indicates that the charge was trapped in the interface area and formed a barrier to the further injection of charge and improving the dielectric performance as a result. Moreover, pulsed electro-acoustic (PEA) short-circuited test after charge injection was carried out, and the change of total charge was calculated. The trend of charge decay in the EFM test is also generally consistent with that in PEA short-circuit test and can be used to verify one another. The results revealed the law of charge movement and verified the interface area can inhibit space charge injection in nano-dielectric at the microscale, which provides an experimental reference for relevant theoretical research

Thermoelectric Materials: Multi‐Scale Microstructural Thermoelectric Materials: Transport Behavior, Non‐Equilibrium Preparation, and Applications (Adv. Mater. 20/2017)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137337/1/adma201770137.pd

Comparison of glycerophospholipid and sphingolipid in mature milk from different sampled regions in the Chinese human milk project (CHMP) study

Milk phospholipids (PLs) are critical components of infant growth. This study aimed to discover PL in mature human milk (HM) from China (n = 201) and mainly assessed the effect caused by sampled regions. The average total PL concentration was quantified from 3.65 to 11.25 mg per g of lipid, and the major PL class identified was sphingomyelin (SM, 38.06–47.62 %), followed by phosphatidylcholine (PC, 29.61–34.39 %), and phosphatidylethanolamine (PE, 10.54–24.46 %). In addition, the 36:2 (18:0/18:2), 38:6 (16:0/22:6), 40:1 (d18:1/22:0), and 42:2 (d18:1/24:1) were the most abundant molecular species identified in glycerophospholipid and SM molecular species respectively. Some PL molecular species were strongly related with region of sampling, like lysophosphatidylinositol 18:1 was only detected in Beijing. In conclusion, those findings showed that the PL molecular species and concentration of HM had significant regional diversity, and it will give the Chinese human milk database more accurate PL data

Data_Sheet_1_Unraveling the rate-limiting step in microorganisms' mediation of denitrification and phosphorus absorption/transport processes in a highly regulated river-lake system.docx

River–lake ecosystems are indispensable hubs for water transfers and flow regulation engineering, which have frequent and complex artificial hydrological regulation processes, and the water quality is often unstable. Microorganisms usually affect these systems by driving the nutrient cycling process. Thus, understanding the key biochemical rate-limiting steps under highly regulated conditions was critical for the water quality stability of river–lake ecosystems. This study investigated how the key microorganisms and genes involving nitrogen and phosphorus cycling contributed to the stability of water by combining 16S rRNA and metagenomic sequencing using the Dongping river–lake system as the case study. The results showed that nitrogen and phosphorus concentrations were significantly lower in lake zones than in river inflow and outflow zones (p < 0.05). Pseudomonas, Acinetobacter, and Microbacterium were the key microorganisms associated with nitrate and phosphate removal. These microorganisms contributed to key genes that promote denitrification (nirB/narG/narH/nasA) and phosphorus absorption and transport (pstA/pstB/pstC/pstS). Partial least squares path modeling (PLS-PM) revealed that environmental factors (especially flow velocity and COD concentration) have a significant negative effect on the key microbial abundance (p < 0.001). Our study provides theoretical support for the effective management and protection of water transfer and the regulation function of the river–lake system.</p