Cervical cancer is one of the leading causes of cancer death among females worldwide and its behavior epidemiologically likes a venereal disease of low infectiousness. Early age at first intercourse ...and multiple sexual partners have been shown to exert strong effects on risk. The wide differences in the incidence among different countries also influenced by the introduction of screening. Although the general picture remains one of decreasing incidence and mortality, there are signs of an increasing cervical cancer risk probably due to changes in sexual behavior. Smoking and human papillomavirus (HPV) 16/18 are currently important issues in a concept of multifactorial, stepwise carcinogenesis at the cervix uteri. Therefore, society-based preventive and control measures, screening activities and HPV vaccination are recommended. Cervical cancer screening methods have evolved from cell morphology observation to molecular testing. High-risk HPV genotyping and liquid-based cytology are common methods which have been widely recommended and used worldwide. In future, accurate, cheap, fast and easy-to-use methods would be more popular. Artificial intelligence also shows to be promising in cervical cancer screening by integrating image recognition with big data technology. Meanwhile, China has achieved numerous breakthroughs in cervical cancer prevention and control which could be a great demonstration for other developing and resource-limited areas. In conclusion, although cervical cancer threatens female health, it could be the first cancer that would be eliminated by human beings with comprehensive preventive and control strategy.
Nanometric iron(III) oxide has been of great interest in a wide range of fields due to its magnetic properties, eminent biochemical characteristics, and potential for technological applications. ...Among iron oxides, ε-Fe2O3 is considered as a remarkable phase due to its giant coercive field at room temperature and ferromagnetic resonance capability. Here we present the first size-dependent phase map for ε-Fe2O3 via a γ → ε → α pathway together with the activation energies for the phase transformations, based on X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). HRTEM images of ε-Fe2O3 nanocrystals show both inversion and pseudohexagonal twins, which are fundamentally important for understanding the correlation between its nanostructure and magnetic properties. Two activation energies for γ-Fe2O3 → α-Fe2O3 phase transformations are 186.37 ± 9.89 and 174.58 ± 2.24 kJ mol–1, respectively. The results provide useful information about the size, crystal structure, and transformation of the nanometric iron oxide polymorphs for applications in areas of developing engineered materials.
A newly discovered piezoelectrochemical (PZEC) effect for the direct conversion of mechanical energy to chemical energy is applied for the mechanically induced degradation of a dye of C.I. Acid ...Orange (AO7) from aqueous solution in the presence of BaTiO3 microdendrites. The mechanism of the PZEC degradation of the dye depends on the ultrasonic vibration used, in which the formation of the strain-induced electric charges on the dendrite surface is due to the deformation and local charge accumulation on the BaTiO3. With sufficient applied electric potential, strained piezoelectric dendrites in AO7 aqueous solution triggered the decomposition reaction. The process is monitored by following the decolorization rate of AO7. The effects of pH, catalyst loading, and initial dye concentration on dye degradation were also studied. Kinetic analyses reveal that the PZEC degradation rates of AO7 can be approximated in terms of the Langmuir–Hinshelwood model. The value of the adsorption equilibrium constant, K AO7, was 0.149 (mgl–1)−1, and the value of the kinetic rate constant of the surface reaction, k c, was 0.50 mgl–1 min–1. These new strain-induced chemical reactions can provide a simple and cost-effective technology for decomposing organic pollutants in aqueous solution by scavenging waste energy such as noise or stray environmental vibrations.
Since the discovery of dolomite, numerous attempts have been made to understand its precipitation mechanism at Earth's surface conditions. One such mechanism relies on a relationship with microbial ...life, where laboratory synthesis experiments have shown that specific organic molecules, such as polysaccharides, exopolymeric substances and hydrogen sulphide can promote dolomite precipitation. Other mechanisms for precipitating dolomite focus on abiotic chemical environments, such as adding dissolved silica, which lower the dehydration energy barrier for the surface Mg2+‐water complex and promote disordered dolomite precipitation. Modern occurrences of dolomite in the Great Salt Lake, Utah, have been studied since the early 20th Century. The distribution of primary dolomite in the Great Salt Lake is spatially heterogeneous, with only the carbonate mud in the South Arm and ridge‐site between desiccation cracks in the North Arm being dominated by dolomite and calcite, while stromatolites in both Arms and ooidal sands in the North Arm are composed entirely of aragonite. It was proposed that dolomite precipitation in the Great Salt Lake was possibly induced by microbial activities such as organic degradation, bacteria sulphate reduction, or other microbial metabolic by‐products. However, these hypotheses could not explain the lack of dolomite in microbial mats, especially in the North Arm, which is constituted by mostly aragonite with no dolomite. Our results suggest that dissolved silica concentration is the primary control for dolomite and Mg‐clay formation in the Great Salt Lake. Even though the North Arm has a much more concentrated Mg and Ca water from lack of freshwater input, dissolved silica levels in the South Arm (>0.5 mm) and the Ridge‐site (ca 0.5 mm) are much higher than in the North Arm (<0.2 mm). Our finding could also provide a new proxy for reconstructing climate changes in the Great Salt Lake area based on dolomite content variation. Phanerozoic dolomite abundance variations may be linked to global CO2 level that facilitates global chemical weathering and dissolved silica input into palaeo‐ocean.
Alzheimer's disease (AD) is the most common neurodegenerative disease, resulting in the loss of cognitive ability and memory. However, there is no specific treatment to mechanistically inhibit the ...progression of Alzheimer's disease, and most drugs only provide symptom relief and do not fundamentally reverse AD. Current studies show that triggering receptor expressed on myeloid cells 2 (TREM2) is predominantly expressed in microglia of the central nervous system (CNS) and is involved in microglia proliferation, survival, migration and phagocytosis. The current academic view suggests that TREM2 and its ligands have CNS protective effects in AD. Specifically, TREM2 acts by regulating the function of microglia and promoting the clearance of neuronal toxic substances and abnormal proteins by microglia. In addition, TREM2 is also involved in regulating inflammatory response and cell signaling pathways, affecting the immune response and regulatory role of microglia. Although the relationship between TREM2 and Alzheimer's disease has been extensively studied, its specific mechanism of action is not fully understood. The purpose of this review is to provide a comprehensive analysis of the research of TREM2, including its regulation of the inflammatory response, lipid metabolism and phagocytosis in microglia of CNS in AD, and to explore the potential application prospects as well as limitations of targeting TREM2 for the treatment of AD.
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•TREM2 plays a crucial role in the pathogenesis of AD.•TREM2 is involved in microglia proliferation, survival, migration and phagocytosis.•TREM2 affects microglia inflammatory response, lipid metabolism and phagocytosis.•Targeted TREM2 therapy for AD has potential application prospects.
With the development of the Internet-of-Things (IoT) industry, more and more fields are involved such as multimedia data. Currently, users rely on videos and images with high data volume, so it has ...brought more challenges for wireless communication and transmission. For multimedia data, it is obviously different from traditional communication data. So new method is required to solve the problem of high data volume in communication. The proactive content caching and the unmanned aerial vehicle (UAV) relaying techniques are deployed over IoT network, enabling the maximum throughput for the served IoT devices. Even though these two existing technologies are important to solve the problem of throughput, there are still other challenges for efficiently improving the system throughput. We mainly study the cache-enabled UAV to maximize throughput among IoT devices in the IoT with the placement of content caching and UAV location. Especially, we divide the joint optimization problem into two parts. First, the UAV deployment problem is decomposed into vertical and horizontal dimensions to ensure the optimal deployment height and 2-D position. The enumeration search method is employed to obtain the 2-D position. Then, we also formulate a concave problem for probabilistic caching placement. Experimental results have indicated that the cache-enabled UAV scheme can obtain a better throughput, which can bring new approach for multimedia data throughput maximization in IoT system.
Hydrothermal experiments at 220, 160, and 130°C were performed to calibrate the Mg isotope fractionation factor between dolomite and aqueous Mg. Hydrothermal experiments included synthesis of ...dolomite using different starting materials, as well as exchange experiments that used poorly-ordered proto-dolomite. The morphology of synthesized dolomite was dependent on starting mineralogy, suggesting that dolomite was synthesized by different pathways. Hydrothermally synthesized dolomite was initially fine-grained disordered or poorly-ordered dolomite that, with time, recrystallized to coarser-grained ordered dolomite. Isotopic exchange was monitored using 87Sr/86Sr ratios and 25Mg tracers, and these indicated near-complete isotope exchange between dolomite and aqueous solutions at the end of most hydrothermal experiments. The Mg isotope fractionation factor between dolomite and aqueous solution obtained from synthesis and exchange experiments converged with time and was independent of dolomite morphology, suggesting attainment of isotopic equilibrium. Combining results from synthesis and exchange experiments, the temperature dependent Mg isotope fractionation factor for ordered dolomite is:Δ26Mgdolo-aq=-0.1554(±0.0096)×106/T2where T is in Kelvin. In contrast, poorly-ordered dolomite has a Δ26Mgdolo-aq fractionation factor that is up to 0.25‰ lower than that of ordered dolomite, and this is attributed to longer Mg–O bonds in imperfectly ordered dolomite. The experimentally calibrated Δ26Mgdolo-aq fractionation factors lie between those calculated by Schauble (2011) and Rustad et al. (2010). The Δ26Mgdolo-aq fractionation factor extrapolated to lower temperatures using the Δ26Mg-T function of this study matches the Δ26Mgdolo-aq fractionation factor obtained by modeling of Mg isotope compositions of ODP drill core samples. This study shows that significant Mg isotope fractionation occurs during dolomite precipitation. These results collectively demonstrate that Mg isotopes in dolomite are a useful tool for studying Mg global cycling and dolomitization.
Dolomite is a common mineral in the rock record. However, the rarity of modern dolomite and the notorious difficulty in synthesizing dolomite abiotically under normal Earth-surface conditions result ...in the long-standing “dolomite problem” in sedimentary geology. Some modern dolomites are associated with sediments where microbial sulfate reduction is active; however, the role of sulfate-reducing bacteria in dolomite formation is still under debate. In this study, we tested the effect of dissolved sulfide on the precipitation of Ca–Mg carbonates, which has been never explored before although dissolved sulfide is one of the major products of microbial sulfate reduction. Our results demonstrated that dissolved sulfide with a concentration of as low as several millimoles can enhance the Mg2+ incorporation into the calcitic structure, and promote the crystallization of high magnesian calcite and disordered dolomite. We also conducted seeded precipitation in experimental solutions containing dissolved sulfide, which showed that calcite seeds can inhibit the precipitation of aragonite and monohydrocalcite (CaCO3·H2O), and induce more Mg2+ incorporation. We propose that accumulated dissolved sulfide in pore waters in organic-rich sediments may trigger the precipitation of disordered dolomite which can be considered as a precursor of some sedimentary dolomite. Our adsorption experiments revealed a strong adsorption of dissolved sulfide onto calcite faces. We suggest that adsorbed dissolved sulfide can lower the energy barrier to the dehydration of Mg2+–water complexes on the growing carbonate surfaces. This study sheds new light on understanding the role of sulfate-reducing bacteria in dolomite formation and the formation mechanism of sedimentary dolomite.
Quantitative understanding of reactivity and stability for a chemical species is fundamental to chemistry. The concept has undergone many changes and additions throughout the history of chemistry, ...stemming from the ideas such as Lewis acids and bases. For a given complexing ligand (Lewis base) and a group of isovalent metal cations (Lewis acids), the stability constants of metal–ligand (ML) complexes can simply correlate to the known properties of metal ions ionic radii (r M n+ ), Gibbs free energy of formation (ΔG°f,M n+ ), and solvation energy (ΔG°s,M n+ ) by 2.303RT log K ML = (α*MLΔG°f,M n+ – β*ML r M n+ + γ*MLΔG°s,M n+ – δ*ML), where the coefficients (α*ML, β*ML, γ*ML, and intercept δ*ML) are determined by fitting the equation to the existing experimental data. Coefficients β*ML and γ*ML have the same sign and are in a linear relationship through the origin. Gibbs free energies of formation of cations (ΔG°f,M n+ ) are found to be natural indices for the softness or hardness of metal cations, with positive values corresponding to soft acids and negative values to hard acids. The coefficient α*ML is an index for the softness or hardness of a complexing ligand. Proton (H+) with the softness index of zero is a unique acid that has strong interactions with both soft and hard bases. The stability energy resulting from the acid–base interactions is determined by the term α*MLΔG°f,M n+ ; a positive product of α*ML and ΔG°f,M n+ indicates that the acid–base interaction between the metal cation and the complexing ligand stabilizes the complex. The terms β*ML r M n+ and γ*MLΔG°s,M n+ , which are related to ionic radii of metal cations, represent the steric and solvation effects of the cations. The new softness indices proposed here will help to understand the interactions of ligands (Lewis bases) with metal cations (Lewis acids) and provide guidelines for engineering materials with desired chemical reactivity and selectivity. The new correlation can also enhance our ability for predicting the speciation, mobility, and toxicity of heavy metals in the earth environments and biological systems.
We propose a mechanism, a piezoelectrochemical effect for the direct conversion of mechanical energy to chemical energy. This phenomenon is further applied for generating hydrogen and oxygen via ...direct water decomposition by means of as-synthesized piezoelectric ZnO microfibers and BaTiO3 microdendrites. Fibers and dendrites are vibrated with ultrasonic waves leading to a strain-induced electric charge development on their surface. With sufficient electric potential, strained piezoelectric fibers (and dendrites) in water triggered the redox reaction of water to produce hydrogen and oxygen gases. ZnO fibers under ultrasonic vibrations showed a stoichiometric ratio of H2/O2 (2:1) initial gas production from pure water. This study provides a simple and cost-effective technology for direct water splitting that may generate hydrogen fuels by scavenging energy wastes such as noise or stray vibrations from the environment. This new discovery may have potential implications in solving the challenging energy and environmental issues that we are facing today and in the future.
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