Low- and high-thermogenic brown adipocyte subpopulations coexist in murine adipose tissue

Brown adipose tissue (BAT), as the main site of adaptive thermogenesis, exerts beneficial metabolic effects on obesity and insulin resistance. BAT has been previously assumed to contain a homogeneous population of brown adipocytes. Utilizing multiple mouse models capable of genetically labeling different cellular populations, as well as single-cell RNA sequencing and 3D tissue profiling, we discovered a new brown adipocyte subpopulation with low thermogenic activity coexisting with the classical high-thermogenic brown adipocytes within the BAT. Compared with the high-thermogenic brown adipocytes, these low-thermogenic brown adipocytes had substantially lower Ucp1 and Adipoq expression, larger lipid droplets, and lower mitochondrial content. Functional analyses showed that, unlike the high-thermogenic brown adipocytes, the low-thermogenic brown adipocytes have markedly lower basal mitochondrial respiration, and they are specialized in fatty acid uptake. Upon changes in environmental temperature, the 2 brown adipocyte subpopulations underwent dynamic interconversions. Cold exposure converted low-thermogenic brown adipocytes into high-thermogenic cells. A thermoneutral environment had the opposite effect. The recruitment of high-thermogenic brown adipocytes by cold stimulation is not affected by high fat diet feeding, but it does substantially decline with age. Our results revealed a high degree of functional heterogeneity of brown adipocytes

Probing Surface Information of Alloy by Time of Flight-Secondary Ion Mass Spectrometer

In recent years, time of flight-secondary ion mass spectrometer (ToF-SIMS) has been widely employed to acquire surface information of materials. Here, we investigated the alloy surface by combining the mass spectra and 2D mapping images of ToF-SIMS. We found by surprise that these two results seem to be inconsistent with each other. Therefore, other surface characteristic tools such as SEM-EDS were further used to provide additional supports. The results indicated that such differences may originate from the variance of secondary ion yields, which might be affected by crystal orientation

Atomic-Scale Imaging of Organic-Inorganic Hybrid Perovskite Using Transmission Electron Microscope

Transmission electron microscope (TEM) is thought as one powerful tool to imaging the atomic-level structure of organic inorganic hybrid perovskite (OIHP) materials, which provides valuable and essential guidance toward high performance OIHP-related devices. However, these OIHPs exhibit poor electron beam stability, severely limiting their practical applications in TEM. Here in this article, the application of TEM to obtain atomic-scale image of OIHPs, main obstacles in identifying the degradation product and future prospects of TEM in the characterization of OIHP materials are reviewed and presented. Three potential strategies (sample protection, low temperature technology, and low-dose technologies) are also proposed to overcome the current drawback of TEM technology

1D Perovskitoid as Absorbing Material for Stable Solar Cells

The instabilities of perovskite solar cells hinder their commercialisation. To resolve this problem, a one-dimensional (1D) perovskitoid, PyPbI3, was fabricated, and its structure and photovoltaic performance were investigated in this work. XPS and FTIR results suggest hydrogen bonds existed in the 1D hexagonal PyPbI3. Stability measurements indicate that 1D perovskitoid is much more stable than the commonly employed FA-based perovskite. In addition, solar cells adopting PyPbI3 as an absorbing layer led to a device lifetime of one month. Our results suggest that 1D perovskitoid has great potential to be employed in solar cells

1D Perovskitoid as Absorbing Material for Stable Solar Cells

The instabilities of perovskite solar cells hinder their commercialisation. To resolve this problem, a one-dimensional (1D) perovskitoid, PyPbI3, was fabricated, and its structure and photovoltaic performance were investigated in this work. XPS and FTIR results suggest hydrogen bonds existed in the 1D hexagonal PyPbI3. Stability measurements indicate that 1D perovskitoid is much more stable than the commonly employed FA-based perovskite. In addition, solar cells adopting PyPbI3 as an absorbing layer led to a device lifetime of one month. Our results suggest that 1D perovskitoid has great potential to be employed in solar cells

Probing Surface Information of Alloy by Time of Flight-Secondary Ion Mass Spectrometer

In recent years, time of flight-secondary ion mass spectrometer (ToF-SIMS) has been widely employed to acquire surface information of materials. Here, we investigated the alloy surface by combining the mass spectra and 2D mapping images of ToF-SIMS. We found by surprise that these two results seem to be inconsistent with each other. Therefore, other surface characteristic tools such as SEM-EDS were further used to provide additional supports. The results indicated that such differences may originate from the variance of secondary ion yields, which might be affected by crystal orientation

Binding Strength and Hydrogen Bond Numbers between COVID-19 RBD and HVR of Antibody

The global battle against the COVID-19 pandemic relies strongly on the human defense of antibody, which is assumed to bind the antigen’s receptor binding domain (RBD) with its hypervariable region (HVR). Due to the similarity to other viruses such as SARS, however, our understanding of the antibody-virus interaction has been largely limited to the genomic sequencing, which poses serious challenges to containment and rapid serum testing. Based on the physical/chemical nature of the interaction, infrared spectroscopy was employed to reveal the binding disparity, the real cause of the antibody-virus specificity at the molecular level, which is inconceivable to be investigated otherwise. Temperature dependence was discovered in the absorption value from the 1550 cm−1 absorption band, attributed to the hydrogen bonds by carboxyl/amino groups, binding the SARS-CoV-2 spike protein and closely resembled SARS-CoV-2 or SARS-CoV-1 antibodies. The infrared absorption intensity, associated with the number of hydrogen bonds, was found to increase sharply between 27 °C and 31 °C, with the relative absorbance matching the hydrogen bonding numbers of the two antibody types (19 vs. 12) at 37 °C. Meanwhile, the ratio of bonds at 27 °C, calculated by thermodynamic exponentials, produces at least 5% inaccuracy. Beyond genomic sequencing, the temperature dependence, as well as the bond number match at 37 °C between relative absorbance and the hydrogen bonding numbers of the two antibody types, is not only of clinical significance in particular but also as a sample for the physical/chemical understanding of vaccine–antibody interactions in general

Enhanced Hydrogen Generation Performance of Al-Rich Alloys by a Melting-Mechanical Crushing-Ball Milling Method

The main problem for the application of hydrogen generated via hydrolysis of metal alloys is the low hydrogen generation rate (HGR). In this paper, active Al alloys were prepared using a new coupled method-melting-mechanical crushing-mechanical ball milling method to enhance the HGR at room temperature. This method contains three steps, including the melting of Al, Ga, In, and Sn ingots with low melting alloy blocks and casting into plates, then crushing alloy plate into powders and ball milling with chloride salts such as NiCl2 and CoCl2 were added during the ball milling process. The microstructure and phase compositions of Al alloys and reaction products were investigated via X-ray diffraction and scanning electron microscopy with energy dispersed X-ray spectroscopy. The low-melting-point Ga-In -Sn (GIS) phases contain a large amount of Al can act as a transmission medium for Al, which improves the diffusion of Al to Al/H2O reaction sites. Finer GIS phases after ball milling can further enhance the diffusion of Al and thus enhance the activity of Al alloy. The hydrogen generation performance through hydrolysis of water with Al at room temperature was investigated. The results show that the H2 generation performance of the Al-low-melting point alloy composite powder is significantly higher than the results reported to date. The highest H2 generation rate and H2 conversion efficiency can reach 5337 mL·min−1·g−1 for the hydrolysis of water with 1 g active alloy

Reversible Phase Transition for Durable Formamidinium-Dominated Perovskite Photovoltaics

Phase instability is one of the major obstacles to the wide application of formamidinium (FA)-dominated perovskite solar cells (PSCs). An in-depth investigation on relevant phase transitions is urgently needed to explore more effective phase-stabilization strategies. Herein, the reversible phase-transition process of FA1−xCsxPbI3 perovskite between photoactive phase (α phase) and non-photoactive phase (δ phase) under humidity, as well as the reversible healing of degraded devices, is monitored. Moreover, through in situ atomic force microscopy, the kinetic transition between α and δ phase is revealed to be the “nucleation–growth transition” process. Density functional theory calculation implies an enthalpy-driven α-to-δ degradation process during humidity aging and an entropy-driven δ-to-α healing process at high temperatures. The α phase of FA1−xCsxPbI3 can be stabilized at elevated temperature under high humidity due to the increased nucleation barrier, and the resulting non-encapsulated PSCs retain >90% of their initial efficiency after >1000 h at 60 °C and 60% relative humidity. This finding provides a deepened understanding on the phase-transition process of FA1−xCsxPbI3 from both thermodynamics and kinetics points of view, which also presents an effective means to stabilize the α phase of FA-dominated perovskites and devices for practical applications