Quartz Fiber Research Articles

Experiments and Theory on Droplet Ignition with Spark Discharges

ABSTRACT Ignition experiments were performed with individual n-decane droplets, initially, about 1 mm in diameter, which were suspended in quartz fibers and subjected to electrical discharges (sparks) of controlled power and duration. Experiments were performed with glow and arc discharges in air at 1 atm and approximately 300 K . Theory is developed to predict the probability of ignition of a fuel droplet as a function of time when it is exposed to an ignition spark. The theory considers the effect of random spark-to-spark fluctuations in the heat flux into the liquid on the time for the droplet surface temperature to be high enough to enable ignition. A Bayesian analysis is also performed to evaluate confidence intervals for parameters related to droplet ignition. Reasonable agreement between theory and experiment is demonstrated, suggesting that spark-to-spark fluctuations of the heat flux into a droplet may lead to a sigmoidal variation of the probability of ignition with respect to time.

Determination of tetramethylammonium hydroxide in air using ion chromatography or ultra-performance liquid chromatography - high-resolution mass spectrometry

Tetramethylammonium hydroxide (TMAH) is extensively utilized in the semiconductor and optoelectronic industries, serving as either a developer or an etchant. TMAH possesses acute toxicity and alkaline corrosiveness, having caused several fatal and injurious accidents in Taiwan. However, there is currently a lack of methods available for assessing TMAH exposure. This study developed a method involving sampling with quartz fiber filters followed by ultrasonic agitation in 10 mL mobile phase, filtering, and analysis using either ion chromatography (IC) or ultra-performance liquid chromatography - high-resolution mass spectrometry (UPLC-HRMS). Utilizing the characteristics of HRMS, the compound analyzed was identified as tetramethylammonium ion (TMA+) through mass spectrometry analysis. The method exhibits excellent trapping capacity and recovery rate. The linear range of TMA+ for IC is 0.3 to 100 μg/mL, with a correlation coefficient of R = 0.9998. The linear range of TMA+ for UPLC-HRMS is 0.002 to 1 μg/mL, with a correlation coefficient of R = 0.996. The recovery rates for IC and HRMS were 116.6% and 90.6%, with corresponding coefficient of variation (CV) of 2.25% and 3.53%, respectively. Samples can be stored at room temperature for 28 days. Verification of this method was conducted at the TMAH factory, and the air concentrations measured in the TMAH filling area were 3.29 and 4.75 μg/m3 from IC and UPLC-HRMS, respectively. This method will be applied in the on-site analysis of occupational hazards for operators in chemical plants, technology factories, and recycling plants, aiming to evaluate risk values to protect the safety and health of workers and prevent occupational diseases.

Hierarchical Ceramic Nanofibrous Aerogels for Universal Passive Radiative Cooling

AbstractSolar‐induced thermal challenges in buildings, cold chain logistics, and spacecrafts may be overcome by integrating passive radiative cooling (PRC) with aerogels having thermal insulation (TI). Herein, a universal radiative cooling silica aerogel (UCSA) is prepared through the simple regeneration and freeze‐drying of commercial quartz fiber membranes. The optically engineered UCSA with a hybrid structure (silica nanofibers/microbeads) achieves remarkable solar reflectance (RS.E. = 98.1%) and atmospheric transparency window emittance (εATW = 92.1%) under Earth conditions, with a theoretical daytime cooling power of 103.3 W m−2. In the harsh space environment, it exhibits ultrahigh average solar reflectance (RS.E. = 99.1%) and broadband mid‐infrared emittance (εMIR = 90%), achieving a cooling power of 354.1 W m−2. Compared to single‐functional approaches, UCSA synergistically integrates the PRC and TI performance for excellent thermal management capability. Moreover, this ceramic aerogel can resist temperatures up to 830 °C, safeguarding building occupants and spacecraft electronics. Furthermore, UCSA passes environmental aging and thermal vacuum outgassing tests for long‐term viability both on Earth and in space. Finally, a USCA‐covered box achieves an average sub‐ambient cooling of 18.6 °C when exposed to sunlight. In summary, UCSA opens a path for energy‐efficient and sustainable cooling strategy with universal applications.

Fluorinated polyetherimide as the modifier for synergistically enhancing the mechanical, thermal and dielectric properties of bismaleimide resin and its composites

The aviation industry has a substantial demand for bismaleimide (BMI) resins that possess high toughness, excellent thermal stability, and low dielectric constant, which are critical for wave-transparent materials. This study presents the synthesis of a novel fluorinated polyetherimide (F-PEI) and its integration with BMI resin using an in situ pre-polymerization method. Upon blending 4 wt% F-PEI with bismaleimide resin, the resulting blending resin (BDP-4) demonstrated a significant enhancement in both impact strength (59.6 % increase) and flexural strength (13.9 % increase) compared to the unmodified BMI. Additionally, the glass transition temperature of BDP-4 was enhanced to 299.3 °C, representing a 5 °C increase, and the corresponding dielectric constant (k) and dielectric loss (tan δ) at 15.2 GHz were decreased from 3.02 to 2.96 and from 0.010 to 0.009, respectively. These improvements are attributed to the phase separation induced by the F-PEI content, which engendered a synergistic toughening mechanism beneficial for both thermal and dielectric attributes. Notably, the flexural strength (630.1 MPa), flexural modulus (26.5 GPa), and interlaminar shear strength (67.1 MPa) of quartz fiber reinforced F-PEI/BMI composites (QF/BDP-4) exceeded those of pure BMI composites. The findings indicate that F-PEI modification is an effective strategy for advancing BMI resin performance, with potential applications in high-performance industries such as aerospace and electronics.

Graphene-skinned alumina fiber fabricated through metalloid-catalytic graphene CVD growth on nonmetallic substrate and its mass production

Graphene growth on widely used dielectrics/insulators via chemical vapor deposition (CVD) is a strategy toward transfer-free applications of CVD graphene for the realization of advanced composite materials. Here, we develop graphene-skinned alumina fibers/fabrics (GAFs/GAFFs) through graphene CVD growth on commercial alumina fibers/fabrics (AFs/AFFs). We reveal a vapor-surface-solid growth model on a non-metallic substrate, which is distinct from the well-established vapor-solid model on conventional non-catalytic non-metallic substrates, but bears a closer resemblance to that observed on catalytic metallic substrates. The metalloid-catalytic growth of graphene on AFs/AFFs resulted in reduced growth temperature (~200 °C lower) and accelerated growth rate (~3.4 times faster) compared to that obtained on a representative non-metallic counterpart, quartz fiber. The fabricated GAFF features a wide-range tunable electrical conductivity (1-15000 Ω sq−1), high tensile strength (>1.5 GPa), lightweight, flexibility, and a hierarchical macrostructure. These attributes are inherited from both graphene and AFF, making GAFF promising for various applications including electrical heating and electromagnetic interference shielding. Beyond laboratory level preparation, the stable mass production of large-scale GAFF has been achieved through a home-made roll-to-roll system with capacity of 468-93600 m2/year depending on product specifications, providing foundations for the subsequent industrialization of this material, enabling its widespread adoption in various industries.

Porous Bismuth Vanadate Photoelectrodes for Solar Water Oxidation Reaction

Bismuth vanadate (BiVO4), a material known for its high visible light activity and good stability, is a promising candidate as a photoanode for overall water splitting [1]. Its performance is limited by its relatively short charge carrier diffusion length, which has recently been estimated to be ~15 nm [2]. For these kinds of photo-absorbers, commercial flat transparent conducting oxide (TCO) substrates are unsuitable since the thickness needed to absorb a sufficient amount of light far exceeds the carrier diffusion length. With this in mind, deposition of very thin semiconductor film onto the internal structure of (micro)porous, conducting substrates can ensure sufficient light absorption [3], whilst ensuring the individual film thickness is uniformly lower than the carrier diffusion length. Nanostructured TCO substrates can be fabricated using a convenient template-free technique called glancing angle deposition (GLAD). The glancing angle deposition method can be used to synthesize different variations of highly oriented submicron-sized pillars, ranging from vertical and tilted columns to zig-zag and helical structures with the help of shadowing effects and substrate rotation [4]. The optical and electrical properties of nanostructured TCO’s were found to depend on the type of material and the substrate temperature during deposition. We find that pillars made from tin-doped indium oxide show good conductivity (79 Ohm/sq) and are promising for the fabrication of nanostructured substrates for bismuth vanadate. A recently developed alternative approach is the use of transparent, porous, conducting substrates (TPCS) made from quartz felt, in which the quartz fibers are coated with F-doped SnO2 [5]. We found that a BiVO4 film thickness of 50 nm within these porous substrates is enough to absorb the same amount of light as a compact 400 nm bismuth vanadate film. We will discuss the deposition of BiVO4 into the TPCS substrates and the photoelectrochemical performance of these porous photoanodes.[1] K. Sivula and R. van de Krol, Nat. Rev. Mater. 1, 15010 (2016)[2] M. Schleuning, M. Kölbach, F. F. Abdi, K. Schwarzburg, M. Stolterfoht, R. Eichberger, R. van de Krol, D. Friedrich, H. Hempel, PRX Energy 1, 023008 (2022)[3] U. Björksten, J. Moser and M. Grätzel, Chem. Mater. 6, 858 (1994)[4] M. M. Hawkeye, M. T. Taschuk and M. J. Brett, “Glancing Angle Deposition of Thin Films”, John Wiley & Sons, Ltd., Chichester, UK (2014).[5] M. Caretti, E. Mensi, R.-A. Kessler, L. Lazouni, B. Goldman, L. Carbone, S. Nussbaum, R. A. Wells, H. Johnson, E. Rideau, J.-h. Yum, K. Sivula, Adv. Mater. 35, 2208740 (2023)

(Digital Presentation) Reactive Evaporation of Cr Vapors from Chromia-Alkaline Oxide Mixtures Generated in 800℃ Air and Subsequent Condensation Onto Aluminosilicate Fibers

This research aims to improve fundamental understanding of the reactive evaporation and condensation of Chromium (Cr) vapors, which are generated from Cr containing alloys used in many high-temperature (>500℃) process environments and can form potentially problematic condensed hexavalent (Cr(VI)) species downstream. This study focuses on the effects of alkaline oxides present in the Cr source on the resultant Cr evaporation and condensation. Vapor species were generated by flowing high-temperature (800℃) air containing 3% water vapor over chromia (Cr2O3) and mixtures of chromia with calcium oxide (CaO) or magnesium oxide (MgO) powders. Lab-grade quartz and alumina fiber samples were positioned downstream from the Cr-alkaline oxide source where the temperature decreases (<500℃) to collect condensed vapor species. Total condensed Cr and ratios of oxidation states were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES) and diphenyl carbazide (DPC) colorimetric/direct UV-VIS spectrophotometric analyses. Preliminary results indicate a decrease in partial pressures of generated Cr vapor species as well as a decrease in condensed Cr species on the aluminosilicate fibers when alkaline oxides are present in the Cr source compared to a pure Cr source. These results also indicate presence of hexavalent Cr (Cr(VI)) species condensed on all samples investigated. Computational thermodynamic equilibrium modelling corroborated the experimental results showing partial pressures of produced vapor species in the presence of alkaline oxides as well as stabilities of condensed Cr compounds on the fiber samples. Comparative results and analyses are presented and discussed to help inform mechanistic understanding and future related research and engineering efforts. Figure 1

Anti-oxidative quartz/carbon-braided fiber reinforced ceramizable composites modified with B4C and AlB2: Mechanical robustness, phase evolution and anti-oxidation mechanism

Carbon fiber reinforced ceramizable phenolic resin matrix composites (Cf/CPR) have been widely used in the field of thermal protection materials. However, the industrial application of the Cf/CPR is restricted by its easy oxidation failure under high temperature condition. In this work, a novel antioxidative ceramizable composites modified with AlB2 and B4C (Cf-Qf/CPR) were prepared by using quartz fiber-coated carbon fiber (Cf-Qf) as reinforcements via co-weaving technique. The thermal stability, mechanical properties, interfacial phase evolution and anti-oxidation mechanism of the composites were investigated. The residue yield and the flexural strength of the composites after treatment at 1200°C for 15 min were 93.4 % and 62.4 MPa, increased by 5.4 % and 67.3 % compared with those of Cf/CPR. Quartz fiber and ceramic protective layer showed synergistic effect to improve the oxidation resistance of carbon fiber and PyC, confirming good high temperature mechanical properties and oxidation resistance of as-received composites.

Numerical and experimental study on anisotropic heat transfer behaviors of quartz fabric composite preforms: Multiple micro‐scale models method

AbstractThis paper presents a comprehensive study on anisotropic heat transmission behaviors in quartz fiber fabrics. Considering the random distribution characteristic of fibers within the yarn, an innovative two‐scale finite element method (tFEM) is introduced, incorporating multiple micro‐scale fiber models (MMFM) based on scanning electron microscope (SEM) observations. MMFM are divided into 8 distinct models to capture intricate fiber arrangements. The macro‐scale fabric model is constructed based on the geometric structure analysis by Micro‐CT technology. Both micro‐ and macro‐scale models are assembled with the air matrix to form the two‐phase composite model. The Hot‐Disk thermal analysis instrument is applied to measure the anisotropic thermal conductivity (ATC). Numerical results from MMFM shows more excellent agreements with the experimental ones at 3D orthogonal directions of fabrics, i.e., the error rates of the thermal conductivity in the warp, weft and thickness directions between numerical and experimental methods are all less than 3%, which indicates the tFEM including MMFM in this paper is more accurate than the tFEM including OSMFM. In addition, the temperature distribution and heat transmission differences due to fiber arrangements are simulated and illustrated through the MMFM. Afterwards, temperature drop and isothermal characteristics are demonstrated in this study.Highlights Effects of fiber arrangements on steady heat transfer behaviors at micro‐scale are illustrated. Isothermal and temperature‐drop characteristics at micro‐ and macro‐scale are simulated and studied. The transverse isotropy of thermal conductivity at micro‐scale and the anisotropy of that at macro‐scale are revealed.

Effect of Polycarbosilane (PCS) on the High-Temperature Properties of Phenolic Resin (Phen) Films and Quartz Fiber/Phen-PCS Composites

In this study phenolic resin (Phen)-loaded PCS (Phen-PCS) films were prepared and quartz fiber/Phen-PCS composites based on the resin films were also prepared. The quartz fiber/Phen-PCS composites were prepared by impregnating 2.5 Dimension (2.5D was an arrangement of fibers) quartz fibers using the resin film infusion (RFI) process. The properties of the composites were investigated. The study demonstrated that the density of the composites, after curing gradually increased with the increase in PCS. The flexural strength of the composites exhibited a trend of increasing and then decreasing after curing and pyrolysis at 1100 °C under an N2 atmosphere. The flexural strength of the composites reached 13.73 MPa when the addition of PCS was 30% of the phenolic resin, representing an increase of 74.23% compared to that of the composites without PCS. The porosity was found to be as low as 2.3% after curing and 2.1% after pyrolysis. X-ray diffraction (XRD) analysis and infrared spectroscopy tests demonstrated that ceramicization products, such as SiO2 and SiC, were produced after pyrolysis of the composites containing PCS. This transformation significantly enhanced the ablation resistance of the composites. Butane flame tests were performed, and the lowest line and mass ablation rates were 0.026 mm/s and 0.196 mg/s after curing. The results of the study revealed the potential of PCS as a precursor to improve the mechanical properties and heat resistance of composites, which offers promising material options for high-temperature applications.

Experimental study on mechanical responses of 3D needle‐punched composite preforms at different needling densities: Failure structures, tensile and interlayer peeling strengths

AbstractIn this study, needle‐punched quartz fiber felt / fabrics preforms (NQFFPs) with a wide needling densities (NDs) range from 70 to 280 punches/cm2 were manufactured, then the inner correlation among the NDs, mechanical properties and structural failure modes were studied and revealed. Firstly, the effects of NDs on mechanical strengths, which included tensile and interlayer peeling strengths of NQFFPs, were analyzed through experimental methods. Moreover, MATLAB software was applied to fit the NDs‐mechanical strength curves, then best fitting equations were defined to characterize the change rules between NDs and mechanical strengths. Additionally, with NDs increment, tensile strengths decreased from 0.727 to 0.0925 MPa, whereas interlayer peeling strengths increased from 83.46 to 135.04 N/m. Afterwards, the 3D image technology was utilized to capture failure morphologies of NQFFPs at different NDs from tensile and interlayer peeling experiments, which furtherly revealed the failure mechanisms of NQFFPs at different NDs. This work is significant for the engineering manufacturing and application of needle‐punched preforms and the composites.Highlights Failure structure characteristics of NQFFPs at different NDs were captured. Change rules between NDs and strengths were characterized by math equations. The correlation among NDs, fracture morphologies and strengths was revealed.

Development of an optical fiber core sensor integrated with silver film for chloride ion measurement

This study introduced an optical fiber core sensor designed to measure chloride ions by removing the fiber's coating and cladding, allowing direct interaction between the fiber core and external solutions, thereby enhancing measurement sensitivity. Two types of fibers, plastic and quartz, were evaluated for their efficacy as sensors. Experimental results demonstrated that the fabricated plastic core fiber failed to accurately reflect alterations in external solutions onto the spectrum, making it unsuitable for sensor applications. Conversely, the quartz fiber core, when treated with chloroform to dissolve its cladding, exhibited superior performance due to its wider transmission wavelength range and higher durability. The integration of a silver film on the core further improved the sensor's sensitivity through surface plasmon resonance. The study also explored the impact of thin-film and thick-film formations on sensor performance, with the thin film providing rapid response times and the thick film offering enhanced durability. This advancement holds significant potential for applications in environmental monitoring and the early detection of chloride-induced corrosion in various structural materials.

MODERN APPROACHES TO THE USE OF COMPOSITE MATERIALS IN CONSTRUCTION

A review of the literature on scientific approaches in the development of composite materials and building structures made of composites is carried out. When creating and manufacturing traditional and new composite materials, for example, by additive manufacturing, and when creating structures and structures in engineering calculations, new techniques, finite element computational software systems, and neural network technologies are used, which are used in the creation of modern metal and composite materials, analysis of mechanical characteristics of materials, forecasting loads on the structure, optimization of structures and calculation of their construction characteristics. The distinctive features of modern composite materials are shown. The main types of composite materials are considered: talc, diatomite, calcium carbonate, gibbsite, barium sulfate, feldspar, nepheline, aragonite, calcium carbonate, wool, silk, cotton, linen, jute, wood pulp, asbestos, fiberglass, metal fibers, quartz fibers, basalt fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, carbon fibers, viscose fibers. The physical and mechanical characteristics of composite materials (based on epoxy, aluminum, carbon, magnesium, and nickel matrices) and traditional (steel, aluminum, brick, concrete) building materials are presented. The disadvantages of such composite materials as carbon fiber, fiberglass, organoplastics, textolite, carbon concrete, and polystyrene concrete are presented. Deformation diagrams of some types of fibers for composite materials are considered: high-modulus carbon fibers, high-strength carbon fibers, aramid fibers, glass fibers, and basalt fibers. The advantages of the system of external reinforcement of building structures with composite materials are described. Examples of reinforcement of building structures are considered: reinforced concrete reinforcement; reinforcement of floor slabs; reinforcement of columns; and reinforcement of brick walls.

Lightweight and broadband metamaterial absorber based on ITO impedance film

In this paper, we present a lightweight, broadband metamaterial absorber that exhibits polarization stability and is insensitive to incident angles. The absorber is composed of one layer of indium tin oxide impedance surface, three layers of quartz fiber composite material, and one layer of paper honeycomb on a metal sheet. Our proposed absorber has a 90 % absorptivity bandwidth of 13.19 GHz, ranging from 4.83 GHz to 18.12 GHz at TEM plane wave normal incidence, covering the entire X and Ku band. We illustrate the variation of design parameters and the distribution of electromagnetic field and current to investigate the absorption mechanism. To demonstrate the effectiveness of our design, we fabricate a prototype sample and measure its absorption performance. The results show a bandwidth of 12.38 GHz, ranging from 4.91 GHz to 17.29 GHz, with a low profile of 0.095λL at the lowest operating frequency. The experimental results are in good agreement with the numerical simulation, effectively verifying our proposed design.

Synchronous improvement in mechanical properties and dielectric performance of poly(silylene arylether arylacetylene) by introducing trifluoromethyl groups

AbstractPoly(silylene arylether arylacetylene) (PSEA) resin is a promising material for preparing an advanced wave‐transparent composite because of excellent thermal stability and good dielectric properties. Herein, a novel poly(silylene arylether arylacetylene) resin with trifluoromethyl groups (PSEAF) was synthesized by Grignard coupling reaction, and the effects of the incorporation of trifluoromethyl groups on various properties of PSEAF resin and quartz fiber reinforced composites were investigated. Compared to PSEA, the PSEAF resin exhibits better solubility and processability, and lower apparent activation energy for curing reactions. After thermal curing reactions, the PSEAF resin converts to an amorphous crosslinked network with the temperature at 5% weight loss (Td5) around 470 °C. The cured PSEAF resin possesses improved mechanical properties and dielectric properties. The flexural strength arrives at 64.4 MPa, and the dielectric constant (ε) and dielectric loss (tanδ) at 30 MHz are 2.75 and 4.3 × 10−3, respectively. Besides, the quartz fiber reinforced PSEAF composite simultaneously shows ε of 3.3, theoretical wave transmittance |T|2 of 91.4% at 7 GHz, and flexural strength of 350 MPa.

Innovative Ex-Situ catalyst bed integration for LDPE plastic Pyrolysis: A thermodynamically closed system approach

The recycling of Low-Density Polyethylene (LDPE) poses a significant challenge due to its resistance to degradation and presence of impurities among the waste LDPE. This study introduces an innovative method for LDPE pyrolysis, aiming to enhance the efficiency of LDPE recycling and contribute to the circular economy of plastics. We utilized an HZSM-5 catalyst within a unique setup that incorporates a catalyst bed constructed from a quartz fibre membrane filter. This innovative hybrid method, a combination of in-situ and ex-situ modes, was designed to shield the catalyst from direct contact with undesired materials, thereby facilitating easy catalyst separation at the end of the process. Experiments were conducted in a high-pressure batch reactor, heated to 400 °C within a closed thermodynamic system. Parallel runs were performed for both pure and waste LDPE, with and without the catalyst. The catalytic pyrolysis resulted in an oil output of 40.3 % for waste LDPE and 43.5 % for pure LDPE, with a significant increase in aromatics when comparing thermal to catalytic pyrolysis. The calorific values of the pyrolysis liquids were found to be 46.2 for pure LDPE and 46.1 for waste LDPE, indicating their potential for sustainable hydrocarbon fuel synthesis. Following the catalytic pyrolysis, the spent catalyst underwent stepwise oxidation as a regeneration method, indicating a partial loss of activity but a similar influence on the degradation temperature as the fresh catalyst. This study not only presents a promising approach to LDPE recycling but also offers a comprehensive analysis of both the pyrolysis outputs and the spent catalyst. Such detailed analysis is crucial for refining the LDPE pyrolysis process and facilitating its scale-up for industrial applications.

Winter and Summer PM2.5 Land Use Regression Models for the City of Novi Sad, Serbia

In this study, we describe the development of seasonal winter and summer (heating and non-heating season) land use regression (LUR) models for PM2.5 mass concentration for the city of Novi Sad, Serbia. The PM2.5 data were obtained through an extensive seasonal measurement campaign conducted at 21 locations in urban, urban/industrial, industrial and background areas in the period from February 2020–July 2021. At each location, PM2.5 samples were collected on quartz fibre filters for 10 days per season using a reference gravimetric pump. The developed heating season model had two predictors, the first can be associated with domestic heating over a larger area and the second with local traffic. These predictors contributed to the adjusted R2 of 0.33 and 0.55, respectively. The developed non-heating season model had one predictor which can be associated with local traffic, which contributed to the adjusted R2 of 0.40. Leave-one-out cross-validation determined RMSE/mean absolute error for the heating and non-heating season model were 4.04/4.80 μg/m3 and 2.80/3.17 μg/m3, respectively. For purposes of completeness, developed LUR models were also compared to a simple linear model which utilizes satellite aerosol optical depth data for PM2.5 estimation, and showed superior performance. The developed LUR models can help with quantification of differences between seasonal levels of air pollution, and, consequently, air pollution exposure and association between seasonal long-term exposure and possible health risk implications.

Selective molecular characterization of organic aerosols using in situ laser desorption ionization mass spectrometry.

The sources and chemical compositions of organic aerosol (OA) exert a significant influence on both regional and global atmospheric conditions, thereby having far-reaching implications on environmental chemistry. However, existing mass spectrometry (MS) methods have limitations in characterizing the detailed composition of OA due to selective ionization as well as fractionation during cold-water extraction and solid-phase extraction (SPE). A comprehensive MS study was conducted using aerosol samples collected on dusty, clean, and polluted days. To supplement the data obtained from electrospray ionization (ESI), a strategy for analyzing OAs collected using the quartz fiber filter directly utilizing laser desorption ionization (LDI) was employed. Additionally, the ESI method was conducted to explore suitable approaches for determining various OA compositions from samples collected on dusty, clean, and polluted days. In situ LDI has the advantages of significantly reducing the sample volume, simplifying sample preparation, and overcoming the problem of overestimating sulfur-containing compounds usually encountered in ESI. It is suitable for the characterization of highly unsaturated and hydrophobic aerosols, such as brown carbon-type compounds with low volatility and high stability, which is supplementary to ESI. Compared with other ionization methods, in situ LDI helps provide a complementary description of the molecular compositions of OAs, especially for analyzing OAs in polluted day samples. This method may contribute to a more comprehensive MS analysis of the elusive compositions and sources of OA in the atmosphere.

A novel integrated sensing structure based on double quartz tubes stepped fiber grating and its theoretical study on temperature sensing performance

In this paper, a novel integrated sensing structure based on double quartz tubes stepped fiber grating is proposed, which can effectively solve the measurement inaccuracy problem caused by the traditional fiber Bragg grating (FBG) sealing process. Based on thermoelasticity theory, a mathematical model of the temperature sensing performance of the proposed integrated stepped FBG sensing structure is established, and the structural and material influencing parameters of its sensing performance are investigated by combining with Comsol 6.0 simulation; meanwhile, a sample of the proposed integrated stepped FBG sensing structure is prepared, and the temperature sensing performance is tested by temperature sensing experiments, the temperature sensitivity can reach 35.84pm/ °C, and the temperature resolution is 0.030 °C/pm, which is better than that of the metallized FBG (15.91pm/ °C), and verifies the validity of the theoretical model of the temperature sensing performance of the proposed integrated stepped FBG sensing structure. Finally, the temperature cycling response experiment verifies that the sensing structure based on double quartz tubes stepped fiber grating proposed in this paper can effectively improve the temperature sensing performance of FBG based on effectively solving the problems of the traditional adhesive sealing process.

Preparation of fused silica glass micropatterns via gel method using quartz fiber as reinforcer

The preparation of fused silica glass with microstructural patterns has attracted considerable interest, and the process chain of using nano-silica powders mixed with organic polymers to prepare composites for molding, degreasing, and sintering provides a good solution. However, the potential negative effects of organic residues cannot be avoided. In this study, a pattern stencil replication method with silica gel using high-purity quartz fibers as reinforcement is proposed for preparing micropatterned fused silica glass. The microscopic morphology and mechanical properties before and after silica gel drying and the optical properties of fused silica glass obtained by sintering were evaluated via transmission electron microscopy), three-point bending strength test, scanning electron microscopy, X-ray diffraction spectrum analysis, ultraviolet–visible and infrared measurements. The results showed that quartz fiber as a reinforcer could shorten the drying time of the gel and did not degrade the quality of the fused silica glass obtained by sintering. Laser confocal test results showed that microlens arrays were generated by template replication, demonstrating the feasibility of molding fused silica lens arrays with small feature sizes and providing new ideas for the preparation of bulk fused silica glass or micropatterned glass.