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Metasurface-based flat optics is continuously attracting interest owing to its ability for miniaturization of optical devices and systems. Over the last few years, broadband achromatic metalenses have been extensively studied for focusing and imaging in the visible band. However, it is still a substantial challenge to design an achromatic metalens that can produce high-focusing efficiency and high-consistency focal length over the entire visible spectrum. In this Letter, we propose a polarization-independent achromatic metalens operating at wavelengths from 400 to 760 nm, which comprises only a single layer of cross-shaped and square-ring silicon nitride-based nanopillars on a glass substrate in the transmission mode. Numerical results demonstrate that the achromatic metalens has an average efficiency of 75.9% and a maximum focal shift of less than 0.3λ (λ being the operating wavelength) over the entire visible band, which indicate significant improvement over the previously reported achromatic metalenses for focusing visible light in terms of focal-shift suppression and wideband operation with high efficiency. This study recommends a means to develop a high-quality achromatic metalens for the whole visible spectrum. The proposed approach is also suitable for achromatic metalens designs of other wavebands.

Channeling carbon dioxide The separation of gas molecules with physisorbents can be challenging because there is often a tradeoff between capacity and selectivity. Zhou et al. report a template-free hydrothermal synthesis of the one-dimensional channel zeolite mordenite, in which some silicon was replaced by iron. Rather than forming a powder that requires further shaping, this mechanically stable material self-assembled into monoliths. Iron atoms bound in tetrahedral zeolite sites narrowed the channels and enabled the size-exclusion separation of carbon dioxide (CO 2 ) over nitrogen (N 2 ) and methane. High CO 2 uptake and highly efficient CO 2 –N 2 separation was demonstrated for both dry and humid conditions. Science , aax5776, this issue p. 315

Helicobacter pylori (H. pylori) infection is the strongest risk factor for the occurrence and development of gastric carcinoma. However, the molecular mechanism underlying H. pylori-induced pathogenesis has not yet been fully characterized. Here, we explored whether H. pylori upregulates semaphorin 5A to promote gastric cancer progression via the extracellular regulated protein kinases/matrix metalloproteinase (ERK/MMP9) signaling pathway. In this study, H. pylori upregulated semaphorin 5A expression in vitro and in vivo. Using the human gastric carcinoma cell lines SGC7901, SGC7901-siScrambled, and SGC7901-siSema 5A, our studies showed that H. pylori increased the proliferation, growth, migration, and invasiveness of gastric cancer cells via its effects on semaphorin 5A and that H. pylori increased the expression of MMP9 in gastric cancer cells via the semaphorin 5A-mediated ERK signaling pathway. Further analysis revealed that the ERK inhibitor PD98059 and MMP9 antibody (Ab) attenuated H. pylori-induced gastric cancer cell invasion and metastasis in vitro through a semaphorin 5A-dependent mechanism. In conclusion, H. pylori could promote gastric cancer progression in a semaphorin 5A-dependent manner via the ERK/MMP9 signaling pathway. Semaphorin 5A and its related signaling molecules potentially represent latent targets for H. pylori-related gastric cancer therapy., Graphical abstract, Semaphorin 5A was originally identified as an axonal guidance factor functioning during neuronal development. Our studies showed that H. pylori promotes gastric cancer progression by upregulating semaphorin 5A expression via ERK/MMP9 signaling, which not only provides further information to understand the mechanism of H. pylori carcinogenesis but adds more weight to our knowledge of semaphorin 5A.

Organic matter is a critical factor which regulates nitrogen loss pathways of denitrification and anammox for microbes in marine ecosystems. However, only a little attention has been paid to contrasting studies on denitrification and anammox in sandy and muddy sediments, especially in the coastal continental shelf dominated by sandy sediments. This study determined the bulk properties and associated microbial nitrogen transformation processes of surface sediments in the East China Sea coastal shelf, with the aim of gaining insight into the interaction of nitrogen loss with organic matter at the molecular level. The results illustrate that nitrogen loss dominates in organic-rich muddy sediments, and its denitrification rate (14.39 nmol N g

A series of isostructural lanthanide–quinoxaline-2,3(1H,4H)-dione containing 1D chiral chains shows high sensing effect toward the small solvent molecules, in which tertiary butanol was an excellent sensitizer, while tetrahydrofuran was a highly quenching species.

The modification of wool fabrics is significant in preparation of functional textiles. Sodium periodate oxidized β-cyclodextrin was grafted onto wool fabric through Schiff base reaction to obtain fabric with controlled release property. β-cyclodextrin was oxidized to aldehyde-β-cyclodextrin, and the results show that the inclusion constant and aldehyde content of aldehyde-β-cyclodextrin are varied with the reaction parameters such as molar ratio of reaction agents and the reaction temperature. The degree of oxidation was confirmed by ion chromatography. The drug loading test shows that the oxidized cyclodextrin still had inclusion ability towards phenolphthalein, while the inclusion constant was only 50 % of the original β-CD. The ATR-FTIR spectra proved the occurrence of grafting reaction between the aldehyde groups of aldehyde-β-cyclodextrin and the amino groups on wool fiber. The aldehyde-β-cyclodextrin grafted wool fabric show great washing durability even after 5 washing cycles. Compared with the aldehyde-β-cyclodextrin power, the inclusion ability of aldehyde-β-cyclodextrin fixed on the wool fiber decreased by 60 %.

Zero thermal expansion (ZTE) materials are highly desired in modern industries where high-precision processing is necessary. However, ZTE materials in pure form are extremely rare. The most widely used are Invar alloys, where the ZTE is intimately associated with spontaneous magnetic ordering, known as the magnetovolume effect (MVE). Despite tremendous studies, there is still no consensus on the microscopic origin of MVE in Invar alloys. Here, we report the discovery of room-temperature isotropic ZTE in a pure-form cobaltite perovskite, A-site disordered La0.5Ba0.5CoO3-x. The temperature window of the anomalous thermal expansion shows large tunability by simply altering the oxygen content, making this material a promising candidate for practical applications. Furthermore, we unveil with compelling experimental evidence that the ZTE originates from an isostructural transition between antiferromagnetic large-volume phase and ferromagnetic small-volume phase, which might shed light on the MVE in Invar alloys.

Si/SiO2 composite green body with solid content of 50% was prepared by low toxic gel system and sintered in nitrogen at high temperature. Nitrogen compounds were synthesized in situ on fused silica ceramic substrate. The influence of different temperatures on nitriding reaction was discussed: different temperatures were used for nitriding at 1350 °C, 1400 °C, 1450 °C, 1500 °C. The effect of different nitriding times on nitriding reaction was discussed: different holding times were used for nitriding +1 h, 1.5 h, 2 h and 2.5 h. The best nitriding process was obtained by analyzing the composition, microstructure and properties of the nitrided samples.

Si/SiO2 composite billets were prepared using a low-toxicity gel system, and the resulting billets were sintered at high temperature in nitrogen to synthesize Si2N2O in the central position of the fused silica ceramic matrix. The influences of in situ synthesized Si2N2O on the microstructure and mechanical properties of fused silica ceramics were studied. The results show that Si/SiO2 composite billets can be used to synthesize spike-like and fibrous Si2N2O in situ in nitrogen at 1450 °C. Si2N2O synthesized in situ can improve the mechanical properties and microstructure of quartz ceramics. When the Si/SiO2 composite billet is sintered in nitrogen at 1450 °C for 2 h, the volume density and bending strength of the quartz ceramics can reach 2.36 g/cm3 and 114.37 MPa, respectively.

In order to improve the characters of carrageenan fibers, two different process methods were presented in this study. Dopes prepared directly from Chondrus extraction by Route A—adding NaOH after Chondrus extraction—or Route B—using NaOH solution to extract Chondrus and carrageenan fibers (Fibers A and Fibers B)—were obtained using the wet spinning process using barium chloride as the coagulant at room temperature. The properties of dopes were studied by dynamic light scattering and gel permeation chromatography. The properties of Fibers A and Fibers B were comprehensively studied by Fourier transform infrared, thermal analysis, scanning electron microcopy, and tensile testing. The results showed that carrageenan with a larger molecule weight in Dope A and Fibers A showed higher intensity, better morphology, and stable thermal properties.

In this article, nano-NbC particles toughened Si3N4-based ceramics were prepared by injection moulding and their mechanical properties along with toughening mechanism were studied. An increase of nano-NbC content, gradually homogenizes microstructure of the Si3N4-based ceramics along with increase in its density. However, the fracture toughness and flexural strength first increases and then decreases. The Si3N4-based ceramics demonstrate good comprehensive properties at the 15 wt% nano-NbC content and sintering temperature of 1550 °C (where the density is 85.3%, the flexural strength is 845 MPa, and the fracture toughness is 9.3 MPa·m1/2), Backscattered electron imaging shows that nano-NbC particles can be well dispersed in the Si3N4 ceramic matrix by injection moulding and ceramics are toughened by crack deflection and microcracking effects. It was also found that increasing sintering temperature makes the β-Si3N4 grain distribution more uniform by reducing the porosity.

In this work, the reversible dehydration/hydration process of guanosine dihydrate was studied in detail by a simple heating/cooling process through in situ characterizations such as varying tempera...

β-cyclodextrin (β-CD) was oxidized by sodium periodate to yield a mixture of dialdehyde oligosaccharides. The periodate-oxidized β-CD (O-β-CD) together with chitosan (CTS) was firstly used to finish poly(ethylene terephthalate) (PET) fabrics by immersion-padding method, in which O-β-CD acted as a hydrophilic finishing agent plus a cross-linker. The processes including the periodate oxidization of β-CD and the CTS/O-β-CD hydrophilic finishing of PET fabrics were eco-friendly. The results from the hydroxylamine hydrochloride titration showed that the aldehyde content in O-β-CD was 3.0 mmol/g. With increasing the CTS/O-β-CD mass ratio, the finished fabric had better hydrophilic properties. When the CTS/O-β-CD mass ratio was 1:1, the moisture regain and water drops wetting time of the finished fabric reached 1.85 % and 5.06 s, respectively. They became 1.50 % and 5.70 s, respectively after 25 times of laundering cycle. The occurrence of cross-linking between O-β-CD and CTS was confirmed by the gel test and FT-IR characterization. The cross-linking network deposited on the fiber surface brought on excellent wash resistance of the CTS/O-β-CD finished PET fabrics.

Dynamic physicochemical interactions along continental margins create complex organic carbon (OC) cycles that have a significant impact on the global climate but remain enigmatic; in particular, the OC burial behaviors in mud areas are still unclear. Herein, the molecular and bulk properties of sedimentary OC (SOC) were investigated in eastern China marginal seas to better understand the fate of SOC. The source discrimination analysis showed that SOC was mainly derived from indigenous production and experienced strong heterotrophic alteration, as indicated by low glucosamine/galactosamine ratios (

The bidentate phosphine bis(diphenylphosphino)-N-phenyl-maleimide (L1) is used to synthesize a series of complexes from coinage metals and palladium. Some of them are mononuclear species where one metal atom is coordinated by two phosphine ligands. Three of these complexes have been investigated in detail because they contain the initial ligand in an anionic, radical form (L1') i.e. [Cu(L1L1')] (1), [Ag(L1L1')] (7), [Pd(L1')2] (11). L1' in 1, 7 and 11 shows significant differences in its bonding parameters compared to free or coordinating L1. By magnetic measurements the radical nature of these three compounds could be verified. Quantum chemical calculations prove the existence of either one (1 and 7) or two (11) unpaired electrons localized on the ligand. Furthermore these calculations can explain that 1 and 7 show an asymmetric structure in solid state where one can clearly differ L1 from L1'.

We carried out neutron powder diffraction (NPD) experiments on the layered perovskite cobaltite PrBaCo2O5.5+x (x = 0.24) at Super High Resolution Neutron Powder Diffractometer (SuperHRPD) with a newly installed magnet. At low temperatures, the antiferromagnetic (AFM) reflections of the NPD profile are suppressed whilst ferromagnetic (FM) reflections are enhanced under 14 T magnetic field. The magnetic-field-induced AFM-FM transition reveals the ground-state energy of FM is close to that of AFM.

Tautomeric isomerism is very important in DNA/RNA research, especially base-pair mismatches. However, the tautomeric polymorph of anhydrous guanine (AG) composed of a N7-G purine ring has never been reported in the literature. Herein, a novel crystal phase of anhydrous guanine consisting of a N9-G purine ring was obtained by dehydration of guanine monohydrate (GM) at 111 °C, termed dehydrated-GM, the first reported tautomeric polymorph of AG (N7-G). The dehydration/hydration transformation between GM and dehydrated-GM can be repeated more than 10 times without any observable phase damage. The dehydrated-GM can harvest 8 wt % water within 30 min at relative low humidity (below 20%). Furthermore, dehydrated-GM has long-term stability in a very dry environment when the temperature is in between RT and 150 °C. The channel structure of dehydrated-GM can enlighten the design of materials to harvest water from atmospheric air. The tautomeric polymorphism of N7-G and N9-G purine rings provides a new insight in nu...

Background: To evaluate the prevalence of myopia in school students in Urumqi, China, and explore the influence of the interaction between parental myopia and poor reading and writing habits on myopia to identify the at-risk population and provide evidence to help school students avoid developing myopia.Methods: A cross-sectional survey was conducted with 6,883 school students aged 7–20 years in Urumqi in December 2019. The Standard Eye Chart and mydriatic optometry were used to determine whether students had myopia. Falconer’s method was used to calculate the heritability of parental myopia. Multivariate unconditional logistic regression models were used to analyze the risk factors for myopia and the additive and multiplicative interaction of parental myopia and poor reading and writing habits.Results After standardizing the age of the 6,883 students, the overall prevalence rate of myopia was 47.50%. The heritability of parental myopia was 66.57% for boys, 67.82% for girls, 65.02% for the Han group, and 52.71% for other ethnicities. There were additive interactions between parental myopia and poor reading and writing habits; among them, parental myopia and poor reading and writing habits (1) (the distance between the eyes and book is less than 30 cm when reading and writing, fingers block the sight of one eye while holding the pen, and leaning one’s body when reading and writing) increased the risk of myopia by 10.99 times (odds ratio [OR]=10.99, 95% confidence interval [CI]=8.33–14.68), parental myopia and poor reading and writing habits (2) (reading while lying down, walking, or in the car) increased the risk of myopia by 5.92 times (OR=5.92, 95% CI=4.84–7.27). There was no multiplicative interaction between parental myopia and poor reading and writing habits (1) or (2) (OR=0.69, 95% CI=0.44–1.08; OR=0.89, 95% CI=0.66–1.21, respectively).Conclusion The prevalence of myopia among students in Urumqi, Xinjiang is relatively high. The risk of developing myopia is affected by parental myopia and poor reading and writing habits. In addition, parental myopia amplifies the harm caused by poor reading and writing habits, thereby increasing the risk of myopia. Students with parents who have myopia should be targeted during myopia prevention efforts.

Objectives: The purpose of this study is to investigate a modified Epley maneuver for self-treatment of posterior canal benign paroxysmal positional vertigo (PC-BPPV).Methods: The study recruited 155 patients with PC-BPPV. All patients were randomized into the Epley maneuver group (n = 77) and modified Epley maneuver group (n = 78). We analyzed the resolution rate (1 day and 1 week), residual symptoms after the maneuver, and adverse effects.Results: It was found that the modified Epley maneuver group had a higher resolution rate than that of the Epley maneuver group in the treatment of PC-BPPV after 1 day of the initial maneuver (p < 0.05). However, there was no difference in resolution rate between the Epley maneuver group and the modified Epley maneuver group in resolution rate after 1 week of the initial maneuver (p > 0.05). The modified Epley maneuver group had fewer residual symptoms than that of the Epley maneuver group 1 week after treatment of PC-BPPV (p < 0.05). Significant improvements were also observed in average DHI scores in patients who underwent the modified Epley maneuver compared to the Epley maneuver (p < 0.05). There was no significant difference in adverse effects between the two groups (p > 0.05).Conclusions: The modified Epley maneuver has a satisfactory therapeutic efficacy with less residual symptoms and could be recommended as a self-treatment for patients with PC-BPPV.

Background To evaluate the prevalence of myopia in school students in Urumqi, China, and explore the influence of the interaction between parental myopia and poor reading and writing habits on myopia to identify the at-risk population and provide evidence to help school students avoid developing myopia. Methods A cross-sectional survey was conducted with 6,883 school students aged 7–20 years in Urumqi in December 2019. The Standard Eye Chart and mydriatic optometry were used to determine whether students had myopia. Falconer’s method was used to calculate the heritability of parental myopia. Multivariate unconditional logistic regression models were used to analyze the risk factors for myopia and the additive and multiplicative interaction of parental myopia and poor reading and writing habits. Results After standardizing the age of the 6,883 students, the overall prevalence rate of myopia was 47.50 %. The heritability of parental myopia was 66.57 % for boys, 67.82 % for girls, 65.02 % for the Han group, and 52.71 % for other ethnicities. There were additive interactions between parental myopia and poor reading and writing habits; among them, parental myopia and poor eye habits when reading and writing (the distance between the eyes and book is less than 30 cm when reading and writing, fingers block the sight of one eye while holding the pen, and leaning one’s body when reading and writing; habit 1) increased the risk of myopia by 10.99 times (odds ratio [OR] = 10.99, 95 % confidence interval [CI] = 8.33–14.68), parental myopia and poor reading posture (reading while lying down, walking, or in the car; habit 2) increased the risk of myopia by 5.92 times (OR = 5.92, 95 % CI = 4.84–7.27). There was no multiplicative interaction between parental myopia and habit 1 or habit 2 (OR = 0.69, 95 % CI = 0.44–1.08; OR = 0.89, 95 % CI = 0.66–1.21, respectively). Conclusion The prevalence of myopia among students in Urumqi, Xinjiang is relatively high. The risk of developing myopia is affected by parental myopia and poor reading and writing habits. In addition, parental myopia amplifies the harm caused by poor reading and writing habits, thereby increasing the risk of myopia. Students with parents who have myopia should be targeted during myopia prevention efforts.