DDX20 is required for cell-cycle reentry of prospermatogonia and establishment of spermatogonial stem cell pool during testicular development in mice.

RNA-binding proteins (RBPs), as key regulators of mRNA fate, are abundantly expressed in the testis. However, RBPs associated with human male infertility remain largely unknown. Through bioinformatic analyses, we identified 62 such RBPs, including an evolutionarily conserved RBP, DEAD-box helicase 20 (DDX20). Male germ-cell-specific inactivation of Ddx20 at E15.5 caused T1-propsermatogonia (T1-ProSG) to fail to reenter cell cycle during the first week of testicular development in mice. Consequently, neither the foundational spermatogonial stem cell (SSC) pool nor progenitor spermatogonia were ever formed in the knockout testes. Mechanistically, DDX20 functions to control the translation of its target mRNAs, many of which encode cell-cycle-related regulators, by interacting with key components of the translational machinery in prospermatogonia. Our data demonstrate a previously unreported function of DDX20 as a translational regulator of critical cell-cycle-related genes, which is essential for cell-cycle reentry of T1-ProSG and formation of the SSC pool.

Dual-controlled tunable dual-band and ultra-broadband coherent perfect absorber in the THz range.

This paper proposes a vanadium dioxide metamaterial-based tunable, polarization-independent coherent perfect absorber (CPA) in the terahertz frequency range. The designed CPA demonstrates intelligent reconfigurable switch modulation from an ultra-broadband absorber mode to a dual-band absorber mode via the thermally controlled of VO2. The mode of ultra-broadband absorber is realized when the conductivity of VO2 reaches 11850 S/m via controlling its temperature around T = 328 K. In this mode, the CPA demonstrates more than 90% absorption efficiency within the ultra-wide frequency band that extends from 0.1 THz to 10.8 THz. As the conductivity of VO2 reaches 2×105 S/m (T = 340 K), the CPA switches to a dual-band absorber mode where a relatively high absorption efficiency of 98% and 99.7% is detected at frequencies of 4.5 THz and 9.8 THz, respectively. Additionally, using phase modulation of the incident light, the proposed CPA can regulate the absorption efficiency, which can be intelligently controlled from perfect absorption to high pass-through transmission. Owing to the ability of the proposed CPA to intelligently control the performance of light, this study can contribute towards enhancing the performance of stealth devices, all-optical switches and coherent photodetectors.

Rh(III)-Catalyzed Dual C-H Functionalization and C-O/C-N Annulations of Monoamide Fumarates.

Pyrano[4,3-c]pyridine-diones, which are the key skeleton of bioactive compounds and functional materials, are usually prepared via a multistep synthesis using expensive substrates. This work demonstrates that Rh(III)-catalyzed dual C(sp2)-H functionalization and C-O/C-N annulation of monoamide fumarates can produce pyrano[4,3-c]pyridine-1,5(6H)-diones in high yield (up to 82%) in a single step. The substrates of monoamide fumarates and acetylenes are structurally simple, readily available, and inexpensive. The additive AgSbF6 effectively raised the yields. On account of easier dehydrogenation of OH in the COOH group than NH in the amide group in the reaction, the process first undergoes C-O annulation and then is succeeded by C-N annulation.

Molecular beam homoepitaxy of N-polar AlN: Enabling role of aluminum-assisted surface cleaning.

N-polar aluminum nitride (AlN) is an important building block for next-generation high-power radio frequency electronics. We report successful homoepitaxial growth of N-polar AlN by molecular beam epitaxy (MBE) on large-area, cost-effective N-polar AlN templates. Direct growth without any in situ surface cleaning leads to films with inverted Al polarity. It is found that Al-assisted cleaning before growth enables the epitaxial film to maintain N-polarity. The grown N-polar AlN epilayer with its smooth, pit-free surface duplicates the structural quality of the substrate, as evidenced by a clean and smooth growth interface with no noticeable extended defects generation. Near band-edge photoluminescence peaks are observed at room temperature on samples with MBE-grown layers but not on the bare AlN templates, implying the suppression of nonradiative recombination centers in the epitaxial N-polar AlN.

Osimertinib: Another medication related to osteonecrosis of the jaws? A case report and literature review.

Introduction: Medication-related osteonecrosis of the jaw (MRONJ) is an oral complication in cancer patients being treated with either antiresorptives, mainly denosumab and bisphosphonates, or antiangiogenic drugs. Osimertinib is a third-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) for the treatment of patients with EGFR T790M advanced non-small-cell lung cancer (NSCLC). TKI-induced osteonecrosis of the jaw has been reported in recent years, but these cases almost occur in combination with bisphosphonates, and the data on MRONJ associated to osimertinib is scarce. Case report: We reported a case of MRONJ associated only with osimertinib. A 69-year-old female patient with NSCLC developed MRONJ after 4 years of treatment with osimertinib. Six months ago, she felt persistent pain and swelling in the right maxilla. After 3 months of pain, her dentist extracted one tooth in the right maxilla under local anesthesia. We examined her gingiva and found fistula and pus spillage. A digital volume tomography scan revealed sequestrum. The patient underwent surgical debridement of the necrotic bone under general anesthesia and administered intravenous antibiotics at the hospital. Histopathological analysis of the bone biopsy revealed a diagnosis of MRONJ. Conclusion: This report provides evidence that osimertinib monotherapy can cause MRNOJ, and has a contribution to explore the formation mechanism of MRONJ. For those patients who take osimertinib, routine oral examinations and monitoring should be performed before and during treatment, as well as prompt closure of wounds and antibiotic treatment to avoid infection after invasive oral surgery such as tooth extraction.

Trend reversal from source region to remote tropospheric NO2 columns.

Global tropospheric nitrogen dioxide (NO2) changes have different or even opposite impacts on the photochemical formation of ozone in different regions under different weather and emission condition. However, the changes over regions affected by different levels of human activities are not well known. By using the Ozone Monitoring Instrument (OMI) measurements, we analyzed spatial and temporal variability of tropospheric NO2 vertical column densities (VCDs) from the megacity to the background regions during 2005-2019. Consistent with previous research, our results show a rapid decline of tropospheric NO2 column density over regions strongly affected by human activities, especially for source regions. The decline rates of annual mean NO2 VCDs are up to - 2.44% year-1, - 2.37% year-1, and - 1.43% year-1 over megacities of the USA, Europe, and China, respectively. However, the decreasing rate has slowed, and even reversed to an increasing trend, of tropospheric NO2 from megacities to developing and remote regions, especially over ocean and background areas less affected by anthropogenic activity. From 2005 to 2019, the NO2 VCDs over the ocean and background areas increased for all seasons, with the statistically significant (p < 0.05) trends of 1.15%/0.74% year-1 (MAM), 1.20%/1.06% year-1 (JJA), 1.16%/0.82% year-1 (SON), and 0.68%/0.65% year-1 (DJF), respectively, for ocean/background region. Such decreasing/increasing trends of tropospheric NO2 over sources/remote regions may prevent the ozone air pollution to be effectively resolved to achieve air quality goals worldwide.

Benefits of refined NH3 emission controls on PM2.5 mitigation in Central China.

Atmospheric ammonia (NH3) is one of the most crucial precursors of secondary inorganic aerosols. However, its emission control is still weakness over China. NH3 emission inventories of 2015 with and without considering a set of refined emission reduction strategies covering seven major NH3 emission sources were constructed in Central China. GEOS-Chem model simulations were conducted to quantify the benefits of NH3 emission reduction on PM2.5 mitigation in four typical months (January, April, July and October). The results showed that these control strategies could reduce approximately 47.0% (152 Gg) of the total NH3 emissions in Hubei Province, with the agricultural (livestock and fertilizer application) source being reduced the most (133 Gg). NH3 had a significant nonlinear relationship with sulfate, nitrate, ammonium and PM2.5. NH3 emission reduction exerted less effect on sulfate mitigations (the annual average sensitivity was 4.5%), but it obviously alleviated nitrate, ammonium and thus PM2.5, with the annual average sensitivities of 81.9%, 34.8% and 22.0%, respectively. The average provincial concentrations of PM2.5 were alleviated by 11.2% in January, 10.6% in October, 10.2% in April and 9.3% in July through NH3 emission reduction by 47.0%. The reduction benefits were more pronounced in high NH3 emission areas, such as Yichang, with the PM2.5 reduction of 14.4% in January. This research could provide scientific support for formulating NH3 emission reduction policies to further mitigate PM2.5 pollution.

Recent Advances in Layered-Double-Hydroxides Based Noble Metal Nanoparticles Efficient Electrocatalysts.

With the energy crisis and environmental pollution becoming more and more serious, it is urgent to develop renewable and clean energy. Hydrogen production from electrolyzed water is of great significance to solve the energy crisis and environmental problems in the future. Recently, layered double hydroxides (LDHs) materials have been widely studied in the electrocatalysis field, due to their unique layered structure, tunable metal species and highly dispersed active sites. Moreover, the LDHs supporting noble metal catalysts obtained through the topotactic transformation of LDHs precursors significantly reduce the energy barrier of electrolyzing water, showing remarkable catalytic activity, good conductivity and excellent durability. In this review, we give an overview of recent advances on LDHs supporting noble metal catalysts, from a brief introduction, to their preparation and modification methods, to an overview of their application in the electrocatalysis field, as well as the challenges and outlooks in this promising field on the basis of current development.