Engineering the energy gap near the valence band edge in Mn-incorporated Cu3Ga5Te9 for an enhanced thermoelectric performance

Cu3Ga5Te9-based compounds Cu3-xGa5MnxTe9 (x=0-0.2) with Mn substitution for Cu have been synthesized. The engineered energy gap (∆EA) between impurity and valence band is reduced from 44.4 meV at x=0 to 25.7 meV at x=0.1, which is directly responsible for the reduction of potential barrier for thermal excitation of carriers and enhancement in carrier concentration. However, the Seebeck coefficient shows an increasing tendency with the increasing of determined Hall carrier concentration (n). This anomalous behavior suggests that the Pisarenko plots under assumed effective masses do not fit the current relationship between the Seebeck coefficient and carrier density. With the combination of enhanced electrical conductivities and reduced thermal conductivities at high temperatures, the maximum thermoelectric (TE) figure of merit (ZT) of 0.81 has been achieved at 804 K with x=0.1, which is about 1.65 and 2.9 times the value of current and reported intrinsic Cu3Ga5Te9. The remarkable improvement in TE performance proves that we have succeeded in engineering the energy gap near the valence band edge upon Mn incorporation in Cu3Ga5Te9

Engineering band structure via the site preference of Pb2+ in the In+ site for enhanced thermoelectric performance of In6Se7

Although binary In-Se based alloys as thermoelectric (TE) candidates are of interests in recent years, little attention has been paid into In6Se7 based compounds. With substituting Pb in In6Se7, the preference of Pb2+ in the In+ site has been observed, allowing the Fermi level (Fr) shift towards the conduction band and the localized state conduction becomes dominated. Consequently, the Hall carrier concentration (nH) has been enhanced significantly with the highest nH value being about 2~3 orders of magnitude higher than that of Pb-free sample. Meanwhile, the lattice thermal conductivity (κL) tends to be reduced as nH value increases, owing to an increased phonon scattering on carriers. As a result, a significantly enhanced TE performance has been achieved with the highest TE figure of merit (ZT) of 0.4 at ~850 K. This ZT value is 27 times that of intrinsic In6Se7 (ZT=0.015 at 640 K), which proves a successful band structure engineering through site preference of Pb in In6Se7

The role of excess Sn in Cu4Sn7S16 for modification of the band structure and a reduction in lattice thermal conductivity

In this work, we have investigated the band structures of ternary Cu4Sn7+xS16 (x = 0–1.0) compounds with an excess of Sn, and examined their thermoelectric (TE) properties. First principles calculations reveal that the excess Sn, which exists as Sn2+ and is preferentially located at the intrinsic Cu vacancies, unpins the Fermi level (Fr) and allows Fr to enter the conduction band (CB) at x = 0.5. Accordingly, the Hall carrier concentration (nH) is enhanced by about two orders of magnitude when the x value increases from x = 0 to x = 0.5. Meanwhile, the lattice thermal conductivity (κL) is reduced significantly to 0.39 W K−1 m−1 at 893 K, which is in reasonably good agreement with the estimation using the Callaway model. As a consequence, the dimensionless TE figure of merit (ZT) of the compound Cu4Sn7+xS16 with x = 0.5 reaches 0.41 at 863 K. This value is double that of the stoichiometric Cu4Sn7S16, proving that excess Sn in Cu4Sn7S16 is beneficial for improving the TE performance

Significantly Enhanced Thermoelectric Performance of γ-In2Se3 through Lithiation via Chemical Diffusion

γ-In2Se3 is selected as a thermoelectric candidate because it has a unique crystal structure and thermal stability at relatively high temperatures. In this work we have prepared lithiated γ-In2Se3 through chemical diffusion and investigated its band structures and thermoelectric performance. After lithiation of γ-In2Se3 in lithium acetate (CH3COOLi) solution at 50oC, we have observed a high Hall carrier concentration (nH) up to ≤1.71×1018 cm-3 at room temperature (RT), which is about ∼4 orders of magnitude compared to that of pristine γ-In2Se3. The enhancement in nH is directly responsible for the remarkable improvement in electrical conductivity, and can be elucidated as the Fermi level (Fr) unpinning and moving towards the conduction band (CB) through the dominant interstitial occupation of Li+ in the γ-In2Se3 lattice. Combined with the minimum lattice thermal conductivity (κL=0.30-0.34 WK-1m-1) at ~923 K, the highest ZT value of 0.62-0.67 is attained, which is about 9-10 times that of pristine γ-In2Se3, proving that the lithiation in γ-In2Se3 is an effective approach on the improvement of the thermoelectric performance

Chat2Brain: A Method for Mapping Open-Ended Semantic Queries to Brain Activation Maps

Over decades, neuroscience has accumulated a wealth of research results in the text modality that can be used to explore cognitive processes. Meta-analysis is a typical method that successfully establishes a link from text queries to brain activation maps using these research results, but it still relies on an ideal query environment. In practical applications, text queries used for meta-analyses may encounter issues such as semantic redundancy and ambiguity, resulting in an inaccurate mapping to brain images. On the other hand, large language models (LLMs) like ChatGPT have shown great potential in tasks such as context understanding and reasoning, displaying a high degree of consistency with human natural language. Hence, LLMs could improve the connection between text modality and neuroscience, resolving existing challenges of meta-analyses. In this study, we propose a method called Chat2Brain that combines LLMs to basic text-2-image model, known as Text2Brain, to map open-ended semantic queries to brain activation maps in data-scarce and complex query environments. By utilizing the understanding and reasoning capabilities of LLMs, the performance of the mapping model is optimized by transferring text queries to semantic queries. We demonstrate that Chat2Brain can synthesize anatomically plausible neural activation patterns for more complex tasks of text queries.Comment: 8 pages, 4 figure

Price and volatility transmissions among natural gas, fertilizer, and corn markets: A revisit

In this paper, we revisit price and volatility transmission among natural gas, fertilizer, and corn markets; an important issue was explored in previous work. An update of the results is urgently needed due to the recent enormous price volatility in the commodities, fertilizer, and energy markets. We followed the same methodology as previous work and used the vector error correction model and the multivariate generalized autoregressive heteroskedasticity model, but we adopted a new methodology to gather higher frequency data for fertilizer to estimate the interactions and examine the mechanisms between these market prices. Our results are consistent with previous research showing that natural gas price returns in the short-term are significantly affected by its lagged returns from itself and corn markets, and it will be affected by its lagged return sand fertilizer markets. However, we did not find a significant relationship among fertilizer, corn, and natural gas markets from May to November 2021. Moreover, the lagged conditional volatility of corn prices will affect the conditional volatility in the natural gas market but not vice versa

Biostimulants in dissolved organic matters recovered from anaerobic digestion sludge with alkali-hydrothermal treatment: Nontarget identification by ultrahigh-resolution mass spectrometry

Recovering high-value biomaterials from anaerobic digestion sludge (ADS) has attracted considerable attention. However, the molecular features and biological effects of abundant dissolved organic matters (DOMs) in ADS are still unclear, which limits the efficient recycling and application of these bioproducts. This study investigated the molecular composition and transformation of DOMs recovered from ADS through a mild-temperature alkali-hydrothermal treatment (AHT) with ultrahigh-resolution mass spectrometry and energy spectroscopy, and the fertilizing effects of DOMs were evaluated by rice hydroponics. The results indicated that AHT processes significantly promoted the solubilization and release of DOMs from ADS, where most of DOMs molecules remained unchanged and mainly consisted of N-containing compounds with 1–3 N atoms, featuring aromatic or N-heterocyclic rings. Furthermore, AHT processes at pH of 9–10 induced the hydrolysis of partial protein-like substances in DOMs, which was accompanied by formation of heterocyclic-N compounds. Under AHT at pH of 11–12, protein-like and heterocyclic-N substances were increasingly decomposed into amino-N compounds containing 1 or 5 N atoms, while numerous oxygenated aromatic substances with phytotoxicity were degraded and removed from DOMs. Rice hydroponic test verified that ADS-derived DOMs recovered by AHT process at pH of 12 exhibited the highest bioactivity for rice growth, which was attributed to the abundance of amino compounds and humic substances. This study proposed a novel process for the recovery of high-quality liquid organic fertilizer from ADS through AHT process, which can further enrich the technical options available for the safe utilization of sludge resources

Ring-Opening Polymerization of <i>rac</i>-Lactide with Aluminum Chiral Anilido-Oxazolinate Complexes

A series of dimethylaluminum complexes <b>(L</b>^{<b>1a</b>–<b>i</b>})­AlMe₂ (<b>2a</b>–<b>i</b>, where <b>HL</b>^{<b>1a</b>–<b>i</b>} = 2-(2′-ArNH)­phenyl-4-R₁-oxazoline) bearing chiral, bidentate anilido-oxazolinate ligands have been prepared and characterized. Six of the complexes, in the presence of an alcohol cocatalyst, are shown to be active initiators for the stereoselective ring-opening polymerization of <i>rac</i>-lactide in toluene solution and under bulk conditions, yielding polylactides with a range of tacticity from slightly isotactic to moderately heterotactic. The reactivity and selectivity of these catalysts are discussed on the basis of the effect of their substituents