The Role of Zn in Chalcopyrite CuFeS2: Enhanced Thermoelectric Properties of Cu1–xZnxFeS2 with In Situ Nanoprecipitates

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136267/1/aenm201601299_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136267/2/aenm201601299.pd

Roadmap on energy harvesting materials

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere

Origin of off-centering effect and the influence on heat transport in thermoelectrics

Recently, off-centering behavior has been discovered in a series of thermoelectric materials. This behavior indicates that the constituent atoms of the lattice displace from their coordination centers, leading to the locally distorted state and local symmetry breaking, while the material still retains its original crystallographic symmetry. This effect has been proved to be the root cause of ultralow thermal conductivity in off-centering materials, and is considered as an effective tool to regulate the thermal conductivity and improve the thermoelectric performance. Herein, we present a collection of recently discovered off-centering compounds, discuss their electronic origins and local coordination structures, and illuminate the underlying mechanism of the off-centering effect on phonon transport and thermal conductivity. This paper presents a comprehensive view of our current understanding to the off-centering effect, and provides a new idea for designing high performance thermoelectrics

Isolation of Pure Species of Wild Boletaceae and Optimization of Inducer for Triterpenoid Synthesis in Liquid Culture

Objective: To obtain artificial pure strain of porcini and improve the ability of liquid culture mycelium and production of triterpenoid. Methods: The fresh wild Boletaceae fruit bodies from Yunnan were used for the study, and the parent pure strain was isolated and identified by tissue isolation method; Ca2+, linoleic acid, and mushroom aqueous extract were used as inducing agents to study their effects on the content of triterpenoids in liquid mycelium. Results: A pure strain of NG-3 was obtained by multiple purifications and identified by rDNA-ITS molecular biology as Phlebopus portentosus; the mycelium of NG-3 was observed by SEM, and the lock-like joint morphology mycelium with the ability of fruiting appeared at 8-16 d of cultivation. Three inducers were optimized by response surface methodology. The results showed that the concentration of Ca2+ was 12 mmol/L, the amount of linoleic acid was 4%, and the concentration of mushroom aqueous extract was 155 mg/100 mL, at which time the triterpene content was 6.77 mg/g, which was 76% higher than the triterpene content without inducer. Conclusion: The combination of three inducers can promote the synthesis of triterpenoids and increase their content, which can provide technical parameters to solve the shortage of wild resources and realize the industrialization of functional products of Boletaceae

Self‐Assembling Anti‐Freezing Lamellar Nanostructures in Subzero Temperatures

Abstract The requirement for cryogenic supramolecular self‐assembly of amphiphiles in subzero environments is a challenging topic. Here, the self‐assembly of lamellar lyotropic liquid crystals (LLCs) are presented to a subzero temperature of −70 °C. These lamellar nanostructures are assembled from specifically tailored ultra‐long‐chain surfactant stearyl diethanolamine (SDA) in water/glycerol binary solvent. As the temperature falls below zero, LLCs with a liquid‐crystalline Lα phase, a tilted Lβ phase, and a new folded configuration are obtained consecutively. A comprehensive experimental and computational study is performed to uncover the precise microstructure and formation mechanism. Both the ultra‐long alkyl chain and head group of SDA play a crucial role in the formation of lamellar nanostructures. SDA head group is prone to forming hydrogen bonds with water, rather than glycerol. Glycerol cannot penetrate the lipid layer, which mixes with water arranging outside of the lipid bilayer, providing an ideal anti‐freezing environment for SDA self‐assembly. Based on these nanostructures and the ultra‐low freezing point of the system, a series of novel cryogenic materials are created with potential applications in extremely cold environments. These findings would contribute to enriching the theory and research methodology of supramolecular self‐assembly in extreme conditions and to developing novel anti‐freezing materials

The Role of Zn in Chalcopyrite CuFeS 2

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136267/1/aenm201601299_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136267/2/aenm201601299.pd

Origin of the Distinct Thermoelectric Transport Properties of Chalcopyrite ABTe 2

Despite the same crystal structure and homologous constituent elements, the chalcopyrite compounds ABTe2 (A = Cu, Ag; B = Ga, In) exhibit distinct electronic and thermal transport properties. The aim of this work is to understand the origin of such discrepancy employing experiments and theoretical calculations. The results of Hall coefficient measurements, absorption spectroscopy, and electronic transport studies suggest the deep‐level in‐gap states induced by the native A‐site vacancies play a key role in the observed intrinsic semiconductor to degenerate semiconductor transition and are the origins of the distinct electrical conductivity among ABTe2 compounds. In addition, the cryogenic heat capacity measurements and calculated phonon dispersion relations show that the acoustic and low‐frequency optical modes of AgGaTe2 and AgInTe2 are governed by the vibrations of AgTe clusters while the counterparts of CuGaTe2 and CuInTe2 compounds are dominated by the vibrations of Te atoms, and the coupling between the acoustic and low‐frequency optical modes is notably different among ABTe2 compounds. Specifically, lower avoided‐crossing frequencies, lower sound velocity together with stronger Umklapp process yield lower thermal conductivities of AgGaTe2 and AgInTe2 than CuGaTe2 and CuInTe2. This work provides new insights into the understanding and improvement of electrical and thermal properties toward higher thermoelectric performance of chalcopyrite compounds.Distinct electronic transport properties are observed among ABTe2 (A = Cu, Ag; B = Ga, In) chalcopyrite compounds, resulting from the different physical characteristics of the deep‐level in‐gap states induced by the native A‐site vacancies. Despite the discrepancy in sound velocity, the Grüeneissen parameter together with the coupling between the acoustic and low‐frequency optical modes account for their different thermal transport properties.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163913/1/adfm202005861.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163913/2/adfm202005861_am.pd

Over-Expressing TaSPA-B Reduces Prolamin and Starch Accumulation in Wheat (Triticum aestivum L.) Grains

Starch and prolamin composition and content are important indexes for determining the processing and nutritional quality of wheat (Triticum aestivum L.) grains. Several transcription factors (TFs) regulate gene expression during starch and protein biosynthesis in wheat. Storage protein activator (TaSPA), a member of the basic leucine zipper (bZIP) family, has been reported to activate glutenin genes and is correlated to starch synthesis related genes. In this study, we generated TaSPA-B overexpressing (OE) transgenic wheat lines. Compared with wild-type (WT) plants, the starch content was slightly reduced and starch granules exhibited a more polarized distribution in the TaSPA-B OE lines. Moreover, glutenin and ω- gliadin contents were significantly reduced, with lower expression levels of related genes (e.g., By15, Dx2, and ω-1,2 gliadin gene). RNA-seq analysis identified 2023 differentially expressed genes (DEGs). The low expression of some DEGs (e.g., SUSase, ADPase, Pho1, Waxy, SBE, SSI, and SS II a) might explain the reduction of starch contents. Some TFs involved in glutenin and starch synthesis might be regulated by TaSPA-B, for example, TaPBF was reduced in TaSPA-B OE-3 lines. In addition, dual-luciferase reporter assay indicated that both TaSPA-B and TaPBF could transactivate the promoter of ω-1,2 gliadin gene. These results suggest that TaSPA-B regulates a complex gene network and plays an important role in starch and protein biosynthesis in wheat