Elucidating severe urban haze formation in China Guo, Song; Hu, Min; Zamora, Misti L. ...
Proceedings of the National Academy of Sciences - PNAS,
12/2014, Letnik:
111, Številka:
49
Journal Article
Recenzirano
Odprti dostop
Significance We illustrate the similarity and difference in particulate matter (PM) formation between Beijing and other world regions. The periodic cycle of PM events in Beijing is regulated by ...meteorological conditions. While the particle chemical compositions in Beijing are similar to those commonly measured worldwide, efficient nucleation and growth over an extended period in Beijing are distinctive from the aerosol formation typically observed in other global areas. Gaseous emissions of volatile organic compounds and nitrogen oxides from urban transportation and sulfur dioxide from regional industry are responsible for large secondary PM formation, while primary emissions and regional transport of PM are insignificant. Reductions in emissions of the aerosol precursor gases from transportation and industry are essential to mediate severe haze pollution in China.
As the world’s second largest economy, China has experienced severe haze pollution, with fine particulate matter (PM) recently reaching unprecedentedly high levels across many cities, and an understanding of the PM formation mechanism is critical in the development of efficient mediation policies to minimize its regional to global impacts. We demonstrate a periodic cycle of PM episodes in Beijing that is governed by meteorological conditions and characterized by two distinct aerosol formation processes of nucleation and growth, but with a small contribution from primary emissions and regional transport of particles. Nucleation consistently precedes a polluted period, producing a high number concentration of nano-sized particles under clean conditions. Accumulation of the particle mass concentration exceeding several hundred micrograms per cubic meter is accompanied by a continuous size growth from the nucleation-mode particles over multiple days to yield numerous larger particles, distinctive from the aerosol formation typically observed in other regions worldwide. The particle compositions in Beijing, on the other hand, exhibit a similarity to those commonly measured in many global areas, consistent with the chemical constituents dominated by secondary aerosol formation. Our results highlight that regulatory controls of gaseous emissions for volatile organic compounds and nitrogen oxides from local transportation and sulfur dioxide from regional industrial sources represent the key steps to reduce the urban PM level in China.
The electromagnetic (EM) devices have been widely used in communication, electrical engineering, and medical care. However, EM device is a double‐edged sword for its convenience is followed by signal ...pollution and radiation. Electromagnetic interference (EMI) combat has brought lots of attention to researchers in this field. Researchers have made great efforts in developing electromagnetic wave absorbing and shielding (EMAS) materials to reduce EM wave power density to solve the above problem. However, the great majority of reported EMAS materials are powders and coatings, which possess merely EMAS property. Modern practical application has abundant multiple scenes, including high temperature, intense light, water flow, etc. Under the circumstances, EMAS materials should be functionalized with outstanding tunable absorption bands. Based on field theory in physics, multiexternal fields‐responsive materials are an effective method to deal with the above urgently unsolved problem. Thus, herein, different external field‐responsive materials, including temperature, light, space–time, electrical, wind, density, and flow fields, are focused on. Various action mechanisms, materials synthesis methods, and different macrostructures are summarized in detail. Meanwhile, the developing trends of novel external field‐responsive materials are also discussed in order. Finally, the challenges of designing new type of EMAS devices are mentioned.
The current multifunctional electromagnetic wave absorbing and shielding (EMAS) materials are reviewed. An external field‐responsive strategy is proposed to enrich application scenes, including temperature field, light field, space–time field, electrical field, wind field, density field, and flow field. Action mechanisms and EMAS performance improvements are discussed and concluded.
Based on the panel data of 278 prefecture-level cities in China from 2008 to 2018, this paper adopts DID method to verify the impact of “the Belt and Road initiative” on pollution level of these ...cities, the results are still robust through the placebo test and PSM-DID, the mechanism is also analyzed. The study found that “the Belt and Road initiative” has a significant effect on the emission of wastewater, waste gas and dust of cities in China; the mechanism test shows that “the Belt and Road initiative” has significantly reduced urban environmental pollution by promoting foreign investment, upgrading industrial structure and technological innovation.
Small‐molecule organic fluorophores spectrally active in the 800–950 nm region are sought‐after for their broad potential in biomedical and material applications. We have developed a new family of ...brightly fluorescent dyes (ECX) to meet this challenge. ECX dyes are transparent to the visible region, while strongly absorbing in the NIR region at approximately 880 nm. They emit at around 915 nm with a fluorescence quantum yield up to 13.3 %. ECX dyes exhibit high chemostability, high photostability, and low tendency to aggregate. Other merits of ECX dyes include low degree of solvatochromism and facile post‐synthetic derivatization. ECX dyes potentially make available the 800–950 nm region for spectroscopic and microscopic applications and are also expected to find broad material applications.
Deep into NIR: A class of bright and stable small‐molecule organic fluorophores absorbing and emitting at around 880 nm and 915 nm, respectively, was developed. The dyes are suitable for in vitro and in vivo imaging, and make available the red end of the biological NIR spectral window for microscopic studies. They are also potentially valuable for a range of material‐based applications.
The conserved AAA‐ATPase Msp1 is embedded in the outer mitochondrial membrane and removes mislocalized tail‐anchored (TA) proteins upon dysfunction of the guided entry of tail‐anchored (GET) pathway. ...It remains unclear how Msp1 recognizes its substrates. Here, we extensively characterize Msp1 and its substrates, including the mitochondrially targeted Pex15Δ30, and full‐length Pex15, which mislocalizes to mitochondria upon dysfunction of Pex19 but not the GET pathway. Moreover, we identify two new substrates, Frt1 and Ysy6. Our results suggest that mislocalized TA proteins expose hydrophobic surfaces in the cytoplasm and are recognized by Msp1 through conserved hydrophobic residues. Introducing a hydrophobic patch into mitochondrial TA proteins transforms them into Msp1 substrates. In addition, Pex15Δ30 and Frt1 contain basic inter‐membrane space (IMS) residues critical for their mitochondrial mistargeting. Remarkably, Msp1 recognizes this feature through the acidic D12 residue in its IMS domain. This dual‐recognition mechanism involving interactions at the cytoplasmic and IMS domains of Msp1 and substrates greatly facilitates substrate recognition and is required by Msp1 to safeguard mitochondrial functions.
Synopsis
Outer mitochondrial membrane AAA‐ATPase Msp1 removes mislocalized tail‐anchored proteins to safeguard mitochondrial function. Msp1 detects substrates through a dual recognition mechanism involving interactions in the cytoplasm and the intermembrane space.
The Msp1 N‐domain contains conserved residues critical for substrate recognition and removal.
Hydrophobic residues in the cytoplasmic region of the Msp1 N‐domain interact with exposed hydrophobic surfaces of mislocalized tail‐anchored proteins.
In the intermembrane space, some mislocalized tail‐anchored proteins contain positively‐charged residues critical for their mistargeting and are recognized by the Msp1 D12 residue through electrostatic interactions.
Msp1 removes mislocalized tail‐anchored proteins to safeguard mitochondrial function. Msp1 recognizes substrates through a dual recognition mechanism involving hydrophobic interactions in the cytoplasm and electrostatic interactions in the intermembrane space.
Nucleic acids hold promise as biomolecules for future applications in biomedicine and biotechnology. Their well-defined structures and compositions afford unique chemical properties and biological ...functions. Moreover, the specificity of hydrogen-bonded Watson-Crick interactions allows the construction of nucleic acid sequences with multiple functions. In particular, the development of nucleic acid probes as essential molecular engineering tools will make a significant contribution to advancements in biosensing, bioimaging and therapy. The molecular beacon (MB), first conceptualized by Tyagi and Kramer in 1996, is an excellent example of a double-stranded nucleic acid (dsDNA) probe. Although inactive in the absence of a target, dsDNA probes can report the presence of a specific target through hybridization or a specific recognition-triggered change in conformation. MB probes are typically fluorescently labeled oligonucleotides that range from 25 to 35 nucleotides (nt) in length, and their structure can be divided into three components: stem, loop and reporter. The intrinsic merit of MBs depends on predictable design, reproducibility of synthesis, simplicity of modification, and built-in signal transduction. Using resonance energy transfer (RET) for signal transduction, MBs are further endowed with increased sensitivity, rapid response and universality, making them ideal for chemical sensing, environmental monitoring and biological imaging, in contrast to other nucleic acid probes. Furthermore, integrating MBs with targeting ligands or molecular drugs can substantially support their in vivo applications in theranositics. In this review, we survey advances in bioanalytical and biomedical applications of rationally designed MBs, as they have evolved through the collaborative efforts of many researchers. We first discuss improvements to the three components of MBs: stem, loop and reporter. The current applications of MBs in biosensing, bioimaging and therapy will then be described. In particular, we emphasize recent progress in constructing MB-based biosensors in homogeneous solution or on solid surfaces. We expect that such rationally designed and functionalized MBs will open up new and exciting avenues for biological and medical research and applications.
Cancer metastasis leading to the dysfunction of invaded organs is the main cause of the reduced survival rates in lung cancer patients. However, the molecular mechanism for lung cancer metastasis ...remains unclear. Recently, the increased activity of inflammasome appeared to correlate with the metastatic progression and immunosuppressive ability of various cancer types. Our results showed that the mRNA levels of absence in melanoma 2 (AIM2), one of the inflammasome members, are extensively upregulated in primary tumors compared with normal tissues derived from the TCGA lung adenocarcinoma (LUAD) database. Moreover, Kaplan‐Meier analysis demonstrated that a higher mRNA level of AIM2 refers to a poor prognosis in LUAD patients. Particularly, AIM2 upregulation is closely correlated with smoking history and the absence of EGFR/KRAS/ALK mutations in LUAD. We further showed that the endogenous mRNA levels of AIM2 are causally associated with the metastatic potentials of the tested LUAD cell lines. AIM2 knockdown suppressed but overexpression promoted the migration ability and lung colony–forming ability of tested LUAD cells. In addition, we found that AIM2 upregulation is closely associated with an increased level of immune checkpoint gene set, as well as programmed cell death‐ligand 1 (PD‐L1) transcript, in TCGA LUAD samples. AIM2 knockdown predominantly repressed but overexpression enhanced PD‐L1 expression via altering the activity of PD‐L1 transcriptional regulators NF‐κB/STAT1 in LUAD cells. Our results not only provide a possible mechanism underlying the AIM2‐promoted metastatic progression and immune evasion of LUAD but also offer a new strategy for combating metastatic/immunosuppressive LUAD via targeting AIM2 activity.
The illustration of a possible mechanism for the AIM2‐fostered EMT progression and PD‐L1 expression in the metastatic/immunosuppressive lung adenocarcinoma. AIM2 increases PD‐L1 expression via activating its transcriptional regulators NF‐kB/STAT1.
The X‐site ion in organic–inorganic hybrid ABX3 perovskites (OHPs) varies from halide ion to bridging linkers like HCOO−, N3−, NO2−, and CN−. However, no nitrite‐based OHP ferroelectrics have been ...reported so far. Now, based on non‐ferroelectric (CH3)4NNi(NO2)3, through the combined methodologies of quasi‐spherical shape, hydrogen bonding functionality, and H/F substitution, we have successfully synthesized an OHP ferroelectric, FMeTPNi(NO2)3 (FMeTP=N‐fluoromethyl tropine). As an unprecedented nitrite‐based OHP ferroelectric, the well‐designed FMeTPNi(NO2)3 undergoes the ferroelectric phase transition at 400 K with an Aizu notation of 6/mmmFm, showing multiaxial ferroelectric characteristics. This work is a great step towards not only enriching the molecular ferroelectric families but also accelerating the potential practical applications.
Through a combination of quasi‐spherical shape, hydrogen bonding functionality, and H/F substitution, a molecular perovskite ferroelectric was successfully synthesized, FMeTPNi(NO2)3 (FMeTP=N‐fluoromethyl tropine). As an unprecedented nitrite‐based molecular ferroelectric, it undergoes a ferroelectric phase transition at 400 K with an Aizu notation of 6/mmmFm, showing multiaxial characteristics.
A Rh(III)-catalyzed selective coupling of N-methoxy-1H-indole-1-carboxamide and aryl boronic acids is reported. The coupling is mild and efficient toward diverse product formation, with selective C–C ...and C–C/C–N bond formation. Kinetic isotope effects studies were conducted to reveal a mechanism of C–H activation and electrophilic addition.
Red blood cells (RBCs) during microcirculation, aging and storage, lose N‐acetylneuraminic acid (NANA) and other biomaterials thereby altering cell structures, some properties and functions. Such ...cell damage very likely underlies the serious adverse effects of blood transfusion. However, a controversy has remained since 1961–1977 as to whether with aging, the RBCs, suffering loss of NANA, do have a decreased charge density. Any correlation between the changes in the cell properties with cell aging is also not clear. Therefore, to remove the ambiguity and uncertainty, we carried out multiparameteric studies on Percoll fractions of blood of 38 volunteers (lightest‐young‐Y‐RBCs, densest‐old‐O‐RBCs, two middle fractions).We found that there were striking differences between the properties of Y‐RBCs and O‐RBCs. The ζ‐potential of Y‐RBCs decreased gradually with aging. Studies in parallel on RBC fractions incubated with both positively charged quantum dots and Sambucus Nigra‐fluorescein isothiocyanate (FITC) along with their ζ‐potentials provide for the first time direct visual evidence about the lesser amount of charge density and NANA on O‐RBCs, and a collinear decrease in their respective ζ‐potentials. Close correlation was found between the surface charge on an aging RBC and its structure and functions, from the cell morphology, the membrane deformability to the intracellular Hb structure and oxidation ability. This quantitative approach not only clarifies the picture but also has implications in biology and medicine.
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