Distribution Properties of Internal Air Voids in Ultrathin Asphalt Friction Course

The distribution characteristics of air voids in ultrathin asphalt friction course(UAFC) samples with different gradations and compaction methods were statistically analyzed using X-ray computed tomography(CT) and image analysis techniques. Based on the results, compared with the AC-5 sample, the OGFC-5mixture has a higher air void ratio, a larger air void size and a greater number of air voids, with the distribution of internal air voids being more uniform and their shapes being more rounded. The two-parameter Weibull function was applied to fit the gradation of air voids. The fitting results is good, and the function parameters are sensitive to changes in both mineral gradation and compaction method. Moreover, two homogeneity indices were proposed to evaluate the compaction uniformity of UAFC samples. Compared with the Marshall method,the SGC method is more conducive to improve the compaction uniformity of UAFC samples. The compaction method significantly influences the air void distribution characteristics and compaction uniformity of AC-5sample, but has a less significant impact on OGFC-5 sample. The experimental results in the study provides a solid foundation for further explorations on the internal structure and mixture design of UAFC.

Ultrathin and Air-Stable Lithium Metal Anodes with Superlong Cycling Life in Ether/Ester-Based Electrolytes

Ultrathin and air-stable Li metal anodes hold great promise toward high-energy and high-safety Li metal batteries(LMBs).However,the application of LMBs is technically impeded by existing Li metal anodes with large thickness,high reactivity,and poor performance.Here,we developed a novel and scalable approach for the construction of a 10-μm-thick flexible and air-stable Li metal anode by conformally encapsulating Li within a multifunctional VN film.Specifically,the highly lithiophilic VN layer guides a uniform deposition of Li,while abundant and multilevel pores arising from assembly of ultrathin nanosheets enable a spatially confined immersion of metallic Li,thus ensuring an ultrathin and sandwiched Li anode.More impressively,the strong hydrophobicity of VN surface can effectively improve the stability of anode to humid air,whereas the highly conductive framework greatly boosts charge transfer dynamics and enhances Li utilization and high-rate capability.Benefiting from such fascinating features,the constructed Li-VN anode exhibits ultrastable cycling stability in both ether(2500 h)and carbonate(900 h)electrolytes,respectively.Moreover,even exposed to ambient air for 12 h,the anode still can retain~78%capacity,demonstrating excellent air-defendable capability.This work affords a promising strategy for fabricating high-performance,high-safety,and low-cost LMBs.

Back interface passivation for ultrathin Cu(In,Ga)Se_(2) solar cells with Schottky back contact: A trade-off of electrical effects

Back interface passivation reduces the back recombination of photogenerated electrons, whereas aggravates the blocking of hole transport towards back contact, which complicate the back interface engineering for ultrathin CIGSe solar cells with a Schottky back contact. In this work, theoretical explorations were conducted to study how the two contradictory electrical effects impact cell performance. For ultrathin CIGSe solar cells with a pronounced Schottky potential barrier(E_(h)> 0.2 eV), back interface passivation produces diverse performance evolution trends, which are highly dependent on cell structures and properties. Since a back Ga grading can screen the effect of reduced recombination of photogenerated electrons from back interface passivation, the hole blocking effect predominates and back interface passivation is not desirable. However, when the back Schottky diode merges with the main pn junction due to a reduced absorber thickness,the back potential barrier and the hole blocking effect is much reduced on this occasion. Consequently, cells exhibit the same efficiency evolution trend as ones with an Ohmic contact, where back interface passivation is always advantageous.The discoveries imply the complexity of back interface passivation and provide guidance to manipulate back interface for ultrathin CIGSe solar on TCOs with a pronounced Schottky back contact.

A 10-μm Ultrathin Lithium Metal Composite Anodes with Superior Electrochemical Kinetics and Cycling Stability

Lithium metal is a promising candidate for the promotion of the next generation high energy density batteries.The employment of ultrathin Li metal anode with controllable thickness could enable a higher efficiency of Li utilization.Herein,a simple method to fabricate free-standing 10μm ultrathin Li metal anode is developed in this work.A three-dimensional MnO_(x)-coated CNT framework is constructed through a facile hydrothermal process,utilizing as a host for molten Li infusion,which could not only put forward a simple strategy to modulate the thickness of Li metal film but also restricts the volume expansion.The abundant MnO_(x)nanoparticles acting as lithiophilic sites reduce the Li nucleation barrier and optimize the electrochemical kinetics at the anode/electrolyte interface.As a result,the ultrathin Li composite anode exhibits a superior lifespan expanded to 2000 cycles in a symmetric cell,as well as a better capacity and rate capability than that of bare Li anode in full cell,fulfilling the requirements of high energy density and stable cycling life.Furthermore,a wave-shaped Li metal pouch cell based on the ultrathin Li composite anode is assembled that exhibits remarkable mechanical bending toleration and cyclic stability,demonstrating large potential application in the field of flexible wearable devices.

Early gastric cancer diagnostic ability of ultrathin endoscope loaded with laser light source

BACKGROUND Conventionally, the low luminous intensity, low image resolution, and difficulty in operation have been reported with the ultrathin endoscope. However, it has markedly advanced recently. The improvement of the diagnostic ability is expected.AIM To compare the early gastric cancer diagnostic ability of an ultrathin endoscope loaded with a laser light source and that of the conventional endoscope.METHODS The target subjects were 375 consecutive patients who underwent endoscopy at our hospital for post-endoscopic submucosal dissection follow-up of gastric cancer from January to August 2018. During endoscopy, the ultrathin endoscope was used in 140 patients(37.3%), and the conventional endoscope was used in235 patients(62.7%). Patient background was adjusted using the propensity score matching method, and gastric cancer detection ability was evaluated in the two groups.RESULTS The gastric cancer detection rate was 7.8% in the ultrathin endoscope group and7.0% in the conventional endoscope group, and the mean intragastric observation time was 4.1 ± 1.7 min in the ultrathin endoscope group and 4.1 ± 1.9 min in the conventional endoscope group, showing no significant differences between the groups. Moreover, the biopsy implementation rate was 31.8% in the ultrathin endoscope group and 41.1% in the conventional endoscope group, and the biopsy prediction rate was 17.9% and 13.2%, respectively, showing no significant differences between the groups.CONCLUSION The gastric cancer diagnostic ability of the ultrathin endoscope loaded with a laser light source was comparable to that of the conventional endoscope. The observation time was also comparable. Thus, endoscopy using the ultrathin endoscope loaded with the laser light source would be the first option in screening examinations of gastric cancer due to its low invasion.

Ultrathin 2D Metal–Organic Framework Nanosheets In situ Interpenetrated by Functional CNTs for Hybrid Energy Storage Device

The controllable construction of two-dimensional(2D)metal–organic framework(MOF)nanosheets with favorable electrochemical performances is greatly challenging for energy storage.Here,we design an in situ induced growth strategy to construct the ultrathin carboxylated carbon nanotubes(C-CNTs)interpenetrated nickel MOF(Ni-MOF/C-CNTs)nanosheets.The deliberate thickness and specific surface area of novel 2D hybrid nanosheets can be effectively tuned via finely controlling C-CNTs involvement.Due to the unique microstructure,the integrated 2D hybrid nanosheets are endowed with plentiful electroactive sites to promote the electrochemical performances greatly.The prepared Ni-MOF/C-CNTs nanosheets exhibit superior specific capacity of 680 C g^−1 at 1 A g^−1 and good capacity retention.The assembled hybrid device demonstrated the maximum energy density of 44.4 Wh kg^−1 at a power density of 440 W kg^−1.Our novel strategy to construct ultrathin 2D MOF with unique properties can be extended to synthesize various MOF-based functional materials for diverse applications.

The origin of sulfuryl-containing components in SEI from sulfate additives for stable cycling of ultrathin lithium metal anodes

In the light of wireless and non-fossil society based on portable electronics, electric vehicles, and smart grids, secondary batteries with higher energy density, faster charge, and safer operation are pursued persistently [1]. Nowadays, commercial lithium(Li)-ion batteries have been practically applied in our daily life. However,the energy density of Li-ion batteries based on intercalation chemistry is approaching to the theoretical value due to the limited specific capacity of graphite anode(372 mA h g-1) [2].

Engineering an ultrathin amorphous TiO2 layer for boosting the weatherability of TiO2 pigment with high lightening power

TiO2 pigments are typically coated with inert layers to suppress the photocatalytic activity and improve the weatherability. However, the traditional inert layers have a lower refractive index compared to TiO2, and therefore reduce the lightening power of TiO2. In the present work, a uniform, amorphous, 2.9-nm-thick TiO2 protective layer was deposited onto the surface of anatase TiO2 pigments according to pulsed chemical vapor deposition at room temperature, with Ti Cl4 as titanium precursor. Amorphous TiO2 coating layers exhibited poor photocatalytic activity, leading to a boosted weatherability. Similarly, this coating method is also effective for TiO2 coating with amorphous SiO2 and SnO2 layers. However, the lightening power of amorphous TiO2 layer is higher than those of amorphous SiO2 and SnO2 layers. According to the measurements of photoluminescence lifetime, surface photocurrent density, charge-transfer resistance, and electron spin resonance spectroscopy, it is revealed that the amorphous layer can prevent the migration of photogenerated electrons and holes onto the surface, decreasing the densities of surface electron and hole, and thereby suppress the photocatalytic activity.

A facile path from fast synthesis of Li-argyrodite conductor to dry forming ultrathin electrolyte membrane for high-energy-density allsolid-state lithium batteries

All-solid-state lithium batteries(ASSLBs),utilizing sulfide solid electrolyte,are considered as the promising design on account of their superior safety and high energy density,whereas the time-consuming preparation process of sulfide electrolyte powders and the thickness of electrolyte layer hinder their practical application.Herein,an innovative ultimate-energy mechanical alloying plus rapid thermal processing approach is employed to rapidly synthesize the crystalline Argyrodite-type conductor Li_(5.3)PS_(4.3)ClBr_(0.7)(LPSCIBr)with superior ionic conductivity(11.7 mS cm^(-1)).Furthermore,to realize the higher energy density of the battery,an ultrathin LPSCIBr sulfide electrolyte membrane with superior ionic conductivity of 6.5 mS cm^(-1)is fabricated with the aid of polytetrafluoroethylene(PTFE)binder and the reinforced cellulose mesh.Moreover,a simple solid electrolyte interphase(SEI)is constructed on the surface of lithium metal to enhance anodic stability.Benefiting from the joint efforts of these merits,the modified ASSLBs with a high cell-level energy density of 311 Wh kg^(-1) show an excellent cyclic stability.The assembled all-solid-state Li_(2) S/Li pouch cell can operate even under the severe conditions of bending and cutting,demonstrating the enormous potential of the sulfide electrolyte membrane for ASSLBs application.

Ultrathin endoscope flexibility can predict discomfort associated with unsedated transnasal esophagogastroduodenoscopy

AIM: To evaluate the effects of choice of insertion route and ultrathin endoscope types. METHODS: This prospective study (January-June 2012) included 882 consecutive patients who underwent annual health checkups. Transnasal esophagogastroduodenoscopy (EGD) was performed in 503 patients and transoral EGD in 235 patients using six types of ultrathin endoscopes. Patients were given a choice of insertion route, either transoral or transnasal, prior to EGD examination. For transoral insertion, the endo-scope was equipped with a thin-type mouthpiece and tongue depressor. Conscious sedation was not used for any patient. EGD-associated discomfort was assessed using a visual analog scale (VAS; no discomfort 0maximum discomfort 10). RESULTS: Rates of preference for transnasal insertion were significantly higher in male (male/female 299/204 vs 118/117) and younger patients (56.8 ± 11.2 years vs 61.3 ± 13.0 years), although no significant difference was found in VAS scores between transoral and transnasal insertion (3.9 ± 2.3 vs 4.1 ± 2.5). Multivariate analysis revealed that gender, age, operator, and endoscope were independent significant predictors of VAS for transnasal insertion, although gender, age, and endoscope were those for transoral insertion. Further analysis revealed only the endoscopic flexibility index (EFI) as an independent significant predictor of VAS for transnasal insertion. Both EFI and tip diameter were independent significant predictors of VAS for transoral insertion. CONCLUSION: Flexibility of ultrathin endoscopes can be a predictor of EGD-associated discomfort, especially in transnasal insertion.

Ultrathin Wood Laminae–Thermoplastic Starch Biodegradable Composites

Novel fully biodegradable thermoplastic composite laminates reinforced with ultrathin wood laminae were prepared through a hot-pressing process by using two different thermoplastic starch(TPS)matrices.The microstructure and physical properties of the resulting unidirectional and bidirectional laminates were studied.The investigated materials presented a complex microstructure,in which the porosity of the wood laminae was almost entirely occluded by the polymer matrix.The mechanical behavior of the laminates was strongly affected by the obtained microstructure,and matrix penetration in wood pores led to biodegradable composites with elastic modulus and tensile strength higher than those of their constituents.Finally,thermal welding and thermoformability tests proved how these materials possess features typical of thermoplastic materials.

A Universal Atomic Substitution Conversion Strategy Towards Synthesis of Large‑Size Ultrathin Nonlayered Two‑Dimensional Materials

Nonlayered two-dimensional(2D)materials have attracted increasing attention,due to novel physical properties,unique surface structure,and high compatibility with microfabrication technique.However,owing to the inherent strong covalent bonds,the direct synthesis of 2D planar structure from nonlayered materials,especially for the realization of large-size ultrathin 2D nonlayered materials,is still a huge challenge.Here,a general atomic substitution conversion strategy is proposed to synthesize large-size,ultrathin nonlayered 2D materials.Taking nonlayered CdS as a typical example,large-size ultrathin nonlayered CdS single-crystalline flakes are successfully achieved via a facile low-temperature chemical sulfurization method,where pre-grown layered CdI2 flakes are employed as the precursor via a simple hot plate assisted vertical vapor deposition method.The size and thickness of CdS flakes can be controlled by the CdI2 precursor.The growth mechanism is ascribed to the chemical substitution reaction from I to S atoms between CdI2 and CdS,which has been evidenced by experiments and theoretical calculations.The atomic substitution conversion strategy demonstrates that the existing 2D layered materials can serve as the precursor for difficult-to-synthesize nonlayered 2D materials,providing a bridge between layered and nonlayered materials,meanwhile realizing the fabrication of large-size ultrathin nonlayered 2D materials.

Construction of Ultrathin Layered MXene-TiN Heterostructure Enabling Favorable Catalytic Ability for High-Areal-Capacity Lithium-Sulfur Batteries

Catalysis has been regarded as an effective strategy to mitigate sluggish reaction kinetics and serious shuttle effect of Li-S batteries.Herein,a spherical structure consists of ultrathin layered Ti_(3)C_(2)T_(x)-TiN heterostructures(MX-TiN)through in-situ nitridation method is reported.Through controllable nitridation,highly conductive TiN layer grew on the surface and close coupled with interior MXene to form unique 2D heterostructures.The ultrathin heterostructure with only several nanometers in thickness enables outstanding ability to shorten electrons diffusion distance during electrochemical reactions and enlarge active surface with abundant adsorptive and catalytic sites.Moreover,the(001)surface of TiN is dominated by metallic Ti-3d states,which ensures fast transmitting electrons from high conductive MX-TiN matrix and thus guarantees efficient catalytic performance.Calculations and experiments demonstrate that polysulfides are strongly immobilized on MX-TiN,meanwhile the bidirectional reaction kinetics are catalytically enhanced by reducing the conversion barrier between liquid LiPSs and solid Li_(2)S_(2)/Li_(2)S.As a result,the S/MX-TiN cathode achieves excellent long-term cyclability with extremely low-capacity fading rate of 0.022%over 1000 cycles and remarkable areal capacity of 8.27 mAh cm^(−2) at high sulfur loading and lean electrolytes.

Preparation and Characterization of Polymeric PVDF/PDDA Ultrathin Films

A new method for the production of nanoscaled polymeric multilayer films of ferroelectric PVDF is presented.The ultrathin multilayer films of poly diallyldimethylammonium chloride (PDDA) and polyvinylidene fluoride (PVDF) have been prepared on fuzed quartz substrate by the layer-by-layer self-assembly (LbL-SA) method.The PDDA/PVDF multilayer films with the thickness of 30 nm to 150 nm have been characterized by quartz crystal microbalance (QCM) and infrared spectra (IR) The QCM reveals that the alternant ultrathin films of PVDF and PDDA are well order assembled.The electric property of the ultrathin PDDA/PVDF multilayer films at room temperature is investigated.Experimental results show that property of ultrathin films differed from that of the thick films.

Evaluation of preferable insertion routes for esophagogastroduodenoscopy using ultrathin endoscopes

AIM:To evaluate the discomfort associated with esophagogastroduodenoscopy(EGD)using an ultrathin endoscope through different insertion routes.METHODS:This study(January 2012-March 2013)included 1971 consecutive patients[male/female(M/F),1158/813,57.5±11.9 years]who visited a single institute for annual health checkups.Transnasal EGD was performed in 1394 patients and transoral EGD in 577.EGD-associated discomfort was assessed using a visual analog scale score(VAS score:0-10).RESULTS:Multivariate analysis revealed gender(M vs F:4.02±2.15 vs 5.06±2.43)as the only independent predictor of the VAS score in 180 patients who underwent EGD for the first time;whereas it revealed gender(M vs F 3.60±2.20 vs 4.84±2.37),operator,age group(A:<39 years;B:40-49 years;C:50-59years;D:60-69 years;E:>70 years;A/B/C/D/E:4.99±2.32/4.34±2.49/4.19±2.31/3.99±2.27/3.63±2.31),and type of insertion as independent predictors in the remaining patients.Subanalysis for gender,age group,and insertion route revealed that the VAS score decreased with age regardless of gender and insertion route,was high in female patients regardless of age and insertion route,and was low in males aged over60 years who underwent transoral insertion.CONCLUSION:Although comprehensive analysis revealed that the insertion route may not be an independent predictor of the VAS score,transoral insertion may reduce EGD-associated discomfort in elderly patients.

Broadband visible light absorber based on ultrathin semiconductor nanostructures

It is desirable to have electromagnetic wave absorbers with ultrathin structural thickness and broader spectral absorption bandwidth with numerous applications in optoelectronics.In this paper,we theoretically propose and numerically demonstrate a novel ultrathin nanostructure absorber composed of semiconductor nanoring array and a uniform gold substrate.The results show that the absorption covers the entire visible light region,achieving an average absorption rate more than 90%in a wavelength range from 300 nm to 740 nm and a nearly perfect absorption from 450 nm to 500 nm,and the polarization insensitivity performance is particularly great.The absorption performance is mainly caused by the electrical resonance and magnetic resonance of semiconductor nanoring array as well as the field coupling effects.Our designed broadband visible light absorber has wide application prospects in the fields of thermal photovoltaics and photodetectors.

Single-layer broadband planar antenna using ultrathin high-efficiency focusing metasurfaces

Phase gradient metasurfaces(PGMS) offer a fascinating ability to control the amplitude and phase of the electromagnetic(EM) waves on a subwavelength scale, resulting in new applications of designing novel microwave devices with improved performances. In this paper, a reflective symmetrical element, consisting of orthogonally I-shaped structures, has been demonstrated with an approximately parallel phase response from 15 GHz to 22 GHz, which results in an interesting wideband property. For practical design, a planar antenna is implemented by a well-optimized focusing metasurface and excited by a self-designed Vivaldi antenna at the focus. Numerical and experimental results coincide well. The planar antenna has a series of merits such as a wide 3-d B gain bandwidth of 15–22 GHz, an average gain enhancement of 16 d B, a comparable aperture efficiency of better than 45% at 18 GHz, and also a simple fabrication process. The proposed reflective metasurface opens up a new avenue to design wideband microwave devices.

Accurate determination of anisotropic thermal conductivity for ultrathin composite film

Highly anisotropic thermal conductive materials are of significance in thermal management applications. However,accurate determination of ultrathin composite thermal properties is a daunting task due to the tiny thermal conductance,severely hindering the further exploration of novel efficient thermal management materials, especially for size-confined environments. In this work, by utilizing a hybrid measuring method, we demonstrate an accurate determination of thermal properties for montmorillonite/reduced graphene oxide(MMT/r GO) composite film with a thickness range from 0.2 μm to2 μm. The in-plane thermal conductivity measurement is realized by one-dimensional(1D) steady-state heat conduction approach while the cross-plane one is achieved via a modified 3ω method. As-measured thermal conductivity results are cross-checked with different methods and known materials, revealing the high measurement accuracy. A high anisotropic ratio of 60.5, independent of composite thickness, is observed in our measurements, further ensuring the negligible measurement error. Notably, our work develops an effective approach to the determination of ultrathin composite thermal conductivity, which may promote the development of ultrathin composites for potential thermal-related applications.

Nanometer scale patterning of ultrathin films with a scanning tunneling microscope in ambient environment

ＮａｎｏｍｅｔｅｒｓｃａｌｅｐａｔｔｅｒｎｉｎｇｏｆｕｌｔｒａｔｈｉｎｆｉｌｍｓｗｉｔｈａｓｃａｎｎｉｎｇｔｕｎｎｅｌｉｎｇｍｉｃｒｏｓｃｏｐｅｉｎａｍｂｉｅｎｔｅｎｖｉｒｏｎｍｅｎｔＮａｎｏｍｅｔｅｒｓｃａｌｅｐａｔｔｅｒｎｉｎｇｏｆｕｌｔｒａｔｈ...

Ultrathin Metal Silicate Hydroxide Nanosheets with Moderate Metal-Oxygen Covalency Enables Efficient Oxygen Evolution

Exploring efficient,cost-effective,and durable electrocatalysts for electrochemical oxygen evolution reaction(OER)is pivotal for the large-scale application of water electrolysis.Recent advance has demonstrated that the activity of electrocatalysts exhibits a strong dependence on the surface electronic structure.Herein,a series of ultrathin metal silicate hydroxide nanosheets(UMSHNs)M_(3)Si_(2)O_(5)(OH)_(4)(M=Fe,Co,and Ni)synthesized without surfactant are introduced as highly active OER electrocatalysts.Cobalt silicate hydroxide nanosheets show an optimal OER activity with overpotentials of 287 and 358 m V at 1 and 10 m A cm^(-2),respectively.Combining experimental and theoretical studies,it is found that the OER activity of UMSHNs is dominated by the metal-oxygen covalency(MOC).High OER activity can be achieved by having a moderate MOC as reflected by aσ^(*)-orbital(e_(g))filling near unity and moderate[3d]/[2p]ratio.Moreover,the UMSHNs exhibit favorable chemical stability under oxidation potential.This contribution provides a scientific guidance for further development of active metal silicate hydroxide catalysts.