Search

A microwave photonics radio over fiber link can deliver the radio frequency (RF) signal to realize the antenna remote. When the signal is a broadband and multicarrier RF signal, there are some linear distortions in the link, such as the crossmodulation distortion (XMD) and third-order intermodulation distortion (IMD3). It will destroy the wide-bandwidth performance of the link. Traditional postdigital compensation methods for XMD and IMD3 mitigation extract the baseband signal and reconstruct the compensation signal with calculated compensation factor. Here, a kind of artificial neural network genetic algorithm (ANN-GA) distortion compensation technique is proposed to seek the compensation factor instead of calculations. The neural network algorithm is used to fit the mapping function between the compensation factor and the distortion and give a set of predicted data as the original individual fitness value for the genetic algorithm. Based on the original value, the minimal distortion, the corresponding optimal compensation factors γ and α are found with optimization iterations. Taking advantage of the optimal compensation factors, based on the traditional postdigital compensation method, the distortion is mitigated with a suppression ratio of -84.4 dB. In our paper, the mitigation technology of the XMD and IMD3 can be applied for any kinds of link instead of mathematically modelling the link and calculating the compensation factor. The technology can improve the intelligence and flexibility of microwave photonic link linearization design.

It is of extreme importance to develop a reliable numerical prediction technique to simulate the ballistic response of ceramic armor subjected to high-velocity impact (HVI) to economize the test cost and shorten the design period. In the present manuscript, a series of experiments on tungsten heavy alloy (WHA) fragment’s penetration into 99.5% alumina (AD995) armors are systematically simulated by employing the FE-converting-SPH technique. The numerical results are compared with the experimental counterparts to find that the FE-converting-SPH method is fairly efficient in predicting the depth of penetration, the residual velocity, length and mass of fragment, and reproducing the crack forms of ceramic. The applicability and accuracy of the numerical model in terms of the algorithm, material model parameters and contact definitions are validated. Then, the relevant parameters of the calibrated numerical model are incorporated to explore the influence of cover-layer thickness on the armor performance. A few mechanisms regarding the cover plate have been identified to act on the armor performance, such as the alteration of fracture cone half-angle, proportion of energy absorbed by ceramic, mushrooming deformation of fragment, etc. The result of multi-mechanism superposition is that the best ballistic performance is endued with 1 mm cover-layer armor, which demonstrates a 24.6% improvement over the bi-layer armor with 4.96 g/cm2 area density, only at the cost of 15.7% increase in areal density, when back-plate thickness is held as 2 mm; for a constant area density of 4.96 g/cm2, a 1 mm cover-layer is also expected to be the best choice, with 10.7% improvement in armor performance.

Ozone and byproducts of ozone-initiated reactions are among the primary pollutants in aircraft cabins. However, investigations of the spatial distribution and reaction mechanisms of these pollutants are insufficient. This study established a computational fluid dynamics-based model to evaluate ozone and byproduct distribution, considering ozone reactions in air, adsorption onto surfaces, and byproduct desorption from surfaces. The model was implemented in an authentic single-aisle aircraft cabin and validated by measurements recorded during the aircraft cruise phase. Ozone concentrations in the supply air-dominated area were approximately 50% higher than that in the passenger breathing zone, suggesting that human surfaces represent a significant ozone sink. The deposition velocity onto human bodies was 21.83 m/h, surpassing 3.97 m/h on other cabin interior surface areas. Our model provides a mechanistic tool to analyze ozone and byproduct concentration distributions, which would be useful for assessing passenger health risks and for developing strategies for healthier aircraft cabin environments.

Smoothed Particle Hydrodynamics (SPH) has outstanding advantages in dealing with nonlinear problems. However, it is difficult to find an efficient and accurate non-reflecting boundary for SPH. In this paper, the scaled boundary finite element (SBFE) virtual particle boundary is proposed to model the non-reflecting characteristics of the boundary in SPH. It is implemented by 2–4 layers of SBFE virtual particles whose pressure and velocity are calculated by the Lagrange interpolation from the nearby SBFE nodes. The SBFE virtual particle boundary can effectively and accurately simulate the transmission process of pressure waves on the boundary, and eliminate the influence of the reflecting waves on pressure and velocity fields.

The chemical structure of lignin has an important effect on the lignin pyrolysis product distributions. Therefore, it is of great significance to regulate the selectivity of pyrolysis products by modifying the lignin structure. Herein, deep eutectic solvents (DESs) including choline chloride/ethylene glycol (CE), zinc chloride/ethylene glycol (ZE) and choline chloride/acetic acid, treatment of softwood kraft lignin (SKL) is demonstrated. Systematic characterization indicate that the DESs are not only highly conducive to increasing the hydrogen to carbon efficient ratio, reducing the molecular weight and β-O-4 linkage, but also contributes to the maximum degradation rate and thermal stability of SKL. Noticeably, CE and ZE treatment are significantly improved the amount of H-phenols and C-phenols derived lignin pyrolysis, respectively. In addition, DESs pretreatment are also beneficial to the increment of monomer aromatic hydrocarbons. More importantly, the CE pretreatment contributes to the improvement of bio-oil yield and decrease of char content from lignin pyrolysis.

Volatile organic compounds (VOCs) as a non-negligible aircraft cabin air quality (CAQ) factor influence the health and comfort of passengers and crew members. On-board measurements of carbonyls (short-chain (C1 -C6 )) and other volatile organic compounds (VOCs, long-chain (C6 -C16 )) with a total of 350 samples were conducted in 56 commercial airliner cabins covering 8 aircraft models in this study. The mean concentration for each individual carbonyl compound was between 0.3 and 8.3 μg/m3 (except for acrolein & acetone, average = 20.7 μg/m3 ) similar to the mean concentrations of other highly detected VOCs (long-chain (C6 -C16 ), 97% of which ranged in 0-10 μg/m3 ) in aircraft cabins. Formaldehyde concentrations in flights were significantly lower than in residential buildings, where construction materials are known formaldehyde sources. Acetone is a VOC emitted by humans, and its concentration in flights was similar to that in other high-occupant density transportation vehicles. The variation of VOC concentrations in different flight phases of long-haul flights was the same as that of CO2 concentration except for the meal phase, which indicates the importance of cabin ventilation in diluting the gaseous contaminants, while the sustained and slow growth of the VOC concentrations during the cruising phase in short-haul flights indicated that the ventilation could not adequately dilute the emission of VOCs. For the different categories of VOCs, the mean concentration during the cruising phase of benzene series, aldehydes, alkanes, other VOCs (detection rate > 50%), and carbonyls in long-haul flights was 44.2 µg/m3 , 17.9 µg/m3 , 18.6 µg/m3 , 31.5 µg/m3 , and 20.4 µg/m3 lower than those in short-haul flights, respectively. Carbonyls and d-limonene showed a significant correlation with meal service (p

Carbon dioxide (CO2 ) is an important environmental parameter in aircraft cabins. To understand the most recent, real-time CO2 concentration levels and their key influencing factors in aircraft cabins, we conducted in-flight measurements of 52 randomly selected commercial flights with different aircraft types and durations from August 2017 to August 2019. The spatial temporal characteristics of CO2 concentrations on board were analyzed and summarized. For the flight time scale, the CO2 concentrations during the boarding phase (1680 ± 558 ppmv) were notably higher than that in other phases, whereas the condition of the cruising phase was the lowest in most flights. The flight average CO2 concentrations of the cruising phase were 1253 ± 164 ppmv, and the corresponding estimated outside airflow rates were 6.2 ± 1.3 L/s/p in the economy class across all flights. Single-aisle and twin-aisle flights did not show noticeable differences for the same phases. Relatively uniform CO2 concentrations were observed at different positions of the same class. By comparing the results of this study with those previously reported, CO2 concentrations showed a slightly decreasing trend over the last 30 years. This suggested a slightly increased ventilation rate and potentially superior air quality on board.

The scaled boundary finite element method (SBFEM) has obvious advantages in simulating both finite and infinite domains. However, the present high-order transmission boundary of SBFEM has a problem in numerical stability, especially for 3D fluid–structure interaction (FSI) problems. In this paper, a modified method is put forward to improve the numerical stability of the high-order transmission boundary and the total field formulas of the modified high-order transmission boundary are derived. In the transient response analysis, the nonreflecting characteristics of the infinite fluid domain are simulated by the modified high-order transmission boundary, while the impacts loading is calculated by the total field formulas. Several numerical examples are presented to prove the validity of the modified high-order transmission boundary and the total field formulas.

In this work, several representative green processes were developed to extract the enzymatic lignin and deep eutectic solvents (DESs) isolated lignin from corn straw. The results revealed that enzymatic lignin and DESs isolated lignin had a relatively low and homogeneous molecular weight and DESs isolated lignin shown a higher purity. Enzymatic and DESs isolated lignin showed good representativeness and similar to original herbal lignin structures accompany few aryl ether linkage cleavages and oxidation phenomenon. Among them, the subcritical CO2-assisted autohydrolysis and ChCl/Lac DESs treatment exhibited a higher severity for lignin preparation, and sequence DESs isolated lignin had a better reactivity. The β-O-4 ether bonds and carbon-carbon bonds linkage were further broken up during the Lac and DESs sequence treatment. In short, the described processes showed practical significance for lignin extraction and potential valorization, as well as help to develop more novel strategies for the current biorefinery process.

Semi-volatile organic compounds (SVOCs) are one of the main indoor pollutant categories. Six phthalates (dimethyl phthalate (DMP), diethyl phthalate (DEP), di(isobutyl) phthalate (DiBP), di(nbutyl) phthalate (DnBP), butyl benzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP)) in house dust samples were measured in forty residential apartments in Tianjin and Urumqi in four seasons throughout a year. The measured DEHP dust-phase concentration is in the range: 11.9–699.9 μg/g; and showed obvious differences in different seasons, and the maximum can be 2 times higher than minimum. The DiBP and DnBP showed similar phenomenon. The corresponding gas-phase concentration is estimated considering the influencing factors of indoor temperature, air change rate, particle concentration. Then the dust-gas partition coefficient Kd under different season was obtained through the measured dust-phase concentration and estimated gas-phase concentration. From winter to summer, because the increased temperature leads to higher emission rate, the gas-phase concentration is obviously high in spite of the higher air change rate in summer. The estimated DEHP gas-phase concentration showed obvious differences in different seasons, and the maximum can be about 2 times higher than minimum. The DiBP and DnBP showed similar phenomenon. The lower dust-phase concentration in summer is observed due to the temperature-dependency of the dust-gas partition coefficient. Therefore temperature has the greatest impact on the dust concentration, not influence via emission rate, but influences the partition coefficient Kd.

Graphene oxide/wood (GOW) composite was fabricated by a vacuum-pulse dipping technique, and the resulting composites were characterized by scanning electron microscope (SEM), Raman spectroscopy and thermogravimetric analysis (TGA). As demonstrated, the wood matrix became filled by the dense multilayer graphene oxide (GO) membrane structure, which was formed by the layer-by-layer self-assembly of GO nano-sheets. X-ray diffraction (XRD) revealed that the amorphous GO decreased the composite’s relative degree of crystallinity. Additionally, the filled GO generated improvement in the thermal stability of GOW composites in comparison with that of the natural wood (NW).

Itaconic acid (IA) with its trifunctional structure was first introduced into the wood cell lumen and cell wall, which functions as a grafting anchor for fixing various polymers via strong chemical bonds. Then nano-SiO2 was grafted to the IA-modified wood. Field-emission scanning electron microscope revealed that the grafting experiment was successful and that the modified cell wall thickness increased by 65%. The incorporated hydrophobic nano-SiO2 substructure reduced the wood’s hygroscopicity and improved its dimensional stability. The thermal stability of the new composite was also excellent. The presented approach is simple and efficient and the probability is high that it can be up-scaled to a level of a large-scale engineering material.

Formaldehyde has substantial adverse impacts on human health, and formaldehyde exposure primarily occurs in indoor environments. This study investigated the infiltration rates and indoor formaldehyde concentrations in 5 climate zones of China. In the winter, apartments in northern China suffer from higher indoor formaldehyde concentrations than apartments in southern China. The median indoor formaldehyde concentrations were 56 μ g / m 3 (25%, 75%: 38, 91 μ g / m 3 ) in northern China and 40 μ g / m 3 (25%, 75%: 30, 61 μ g / m 3 ) in southern China. There is a clear decrease in indoor formaldehyde concentrations in China. We also studied the relationships of the indoor air temperature, years of decoration, infiltration rate and source characteristic with formaldehyde concentrations in closed conditions. A multiple regression model that related these factors to the formaldehyde concentrations in closed conditions was constructed ( R 2 = 0.75 ). The optimal curve for the suitable combination of temperature and infiltration rate to maintain low formaldehyde concentrations with the lowest cost was calculated for northern and southern China. By comparing the optimal curve and the state point of each city, we can infer the suitable tendency of indoor temperature and infiltration rate for each city. In Tianjin and Shenyang, apartments are overheating, thus causing a high percentage of some homes to have formaldehyde concentrations above the Chinese national standard. In Shanxi, Xinjiang, Yunnan and the Yangtze River Delta, the infiltration rate should be increased to some extent to achieve better indoor air quality. In Hunan, Hubei and Chongqing, indoor temperatures could be increased to improve indoor thermal comfort.

Semi-volatile organic compounds (SVOCs) are widely used in various indoor materials and their adverse health effects have been increasingly recognized. The gas-phase SVOC concentration in equilibrium with the source material ( y 0 ), as a characteristic parameter for SVOC sources, is mostly assumed to be constant in previous studies. However, decreases in y 0 with time have been observed in some studies. As a first step to reveal the mechanism behind the phenomenon, this study quantitatively investigated the variation of y 0 over time under two conditions: natural exposure to outdoor ambient (Case 1), and storage in a controlled ventilated chamber (Case 2). Three phthalates (Di-iso-butyl Phthalate (DiBP), Di-n-butyl Phthalate (DnBP), and di-(2-ethylhexyl) phthalate (DEHP)) emitted from polyvinyl chloride (PVC) floorings and one flame retardant (tris(2-chloroisopropyl) phosphate, TCPP) emitted from polyurethane foam (PUF) were targeted. Experimental results indicated that, for SVOCs with higher volatility, i.e., DiBP, DnBP, and TCPP, y 0 decreased 16%–49% after 60 days' exposure for Case 1; and 16%–36% for Case 2. For SVOCs with lower volatility, i.e., DEHP, no significant decrease in y 0 was observed after 60 days in both cases; while if prolonging the time to about 1.5 years, a decrease of 38% was observed. Discussion about potential reasons for the decrease of y 0 was presented. The results obtained here provide a further understanding about SVOC source characteristics and therefore help providing source strength for estimating indoor SVOC health exposure.

In the previous design and research on the gear transmission error of the five-axis machine turntable, the selection of the five-axis machine tool turntable gears mainly uses the high-precision gears to avoid excessive transmission errors of the turntable, to meet the design requirements of the turntable. However, the cost of the turntable manufacturing is increased and it causes excess precision and unnecessary waste. In meeting the requirements of accuracy, it is important to distribute the gear transmission error of the turntable reasonably, to avoid the high manufacturing cost of the five-axis machine, improve the technical quality of the five-axis machine turntable and reduce its cost. This paper presented the self-developed five-axis machine turntable for aero-engine blade processing as the carrier, and the optimized genetic algorithm is used as the tool to allocate the precision of the gear transmission system. While to meet the design and use requirements, the gear accuracy level is reduced. The manufacturing cost of the turntable goes down.

Radix aconiti lateralis (Fuzi) is widely used in China as a traditional Chinese medicine for the treatment of asthenia, pain and inflammation. However, its toxic alkaloids often lead to adverse reactions. Currently, most of the toxicity studies on Fuzi are focused on the heart and nervous system, and more comprehensive toxicity studies are needed. In this study, based on the previous reports of Fuzi hepatotoxicity, serum pharmacochemistry and network toxicology were used to screen the potential toxic components of Heishunpian(HSP), a processed product of Fuzi, and to explore the possible mechanism of HSP-induced hepatotoxicity. The results obtained are expressed based on the toxicological evidence chain (TEC). It was found that 22 potential toxic components screened can affect Th17 cell differentiation, Jak-STAT signaling pathway, glutathione metabolism, and other related pathways by regulating AKT1, IL2, F2, GSR, EGFR and other related targets, which induces oxidative stress, metabolic disorders, cell apoptosis, immune response, and excessive release of inflammatory factors, eventually inducing liver damage in rats. This is the first study on HSP-induced hepatotoxicity based on the TEC concept, providing references for further studies on the toxicity mechanism of Fuzi.

In this work, an emerging and efficient strategy for the preparation of lignin samples with different acetylation degree by choline chloride/acetic anhydride (ChCl/Aa) treatment of pine kraft lignin (PKL) is reported, and the effects of efficient pre-acetylation of hydroxyl functional groups on subsequent lignin pyrolysis are also systematically investigated. The results show that the ChCl/Aa displays a high acetylation efficiency towards the aliphatic hydroxyl (~99.1%) and phenolic hydroxyl (~94.0%) of PKL, which enhances the hydrogen to carbon effective ratio of PKL. Noticeably, the ChCl/Aa has a slight effect on β-O-4 of PKL, and the acetylation of hydroxyl is beneficial for the improvement of the maximum degradation rate of PKL. In addition, the acetylation of hydroxyl is also significantly contributed to the increment of the pyrolysis bio-oil yield. Importantly, the relative content of the H-phenols obtained from acetylated lignins pyrolysis shows a positive correlation with the acetylation degree of hydroxyl.

New furniture and wood-based decoration are the major sources of gas pollutant in indoor environments. Ventilation is the most straightforward approach to eliminate the indoor gaseous pollution. There were many studies investigating the VOC emission characteristics of various building materials, but people still can’t answer the question that how long should we ventilate for an acceptable indoor concentration level in the real life. This study monitors the long-term gas pollutant concentration of 14 new student dormitory rooms with newly furnitured beds, desks and closets. The formaldehyde, TVOC, and ammonia concentrations were measured, the concentration of detected composition of VOCs was listed, and the decay rate under natural ventilation was analyzed. To determine the natural ventilation rate, the traditional tracer gas method and fast VOC decay method were compared, then a quick ventilation rate method was proposed. The VOC emission rate from the furniture was also measured at different times during the whole testing period. As the field measurement has many un-controlled factors, a small single room model was built and furnitured with corresponding loading amount of furniture board materials. The influence of furniture density, supplier and room location on VOC emission rates was also analyzed.

Most of the tritium quantity stored in a pressure vessel decays into helium-3 and a tiny part permeates the inner surface of the vessel and enters the wall material with time. The tritium in the wall material not only diffuses in the wall and till permeates out of the vessel through the outer surface, but also decays into helium-3 which remains in the wall. The tritium permeating out of the vessel can contaminate environment and harm human being’s health and safety, therefore it is necessary to realize and control the permeation quantity. Directing at this situation that outer surface of the vessel is provided with general mass transfer boundary condition and the tritium inside the vessel is van der Waals gas, and taking simultaneously both decay and permeation of tritium within the vessel and decay and diffusion and permeation of tritium having permeated into the wall material into consideration, the theoretical model was developed and the theoretical formulas of total permeation quantity and surplus after decay of tritium were deduced. Through analytical calculation, the curves of total permeation quantity and surplus after decay of tritium versus time, total permeation quantity of tritium versus both convectivemass transfer coefficient of the outer surface and the wall thickness of the vessel were plotted and related laws were revealed. Corresponding to the theoretical calculation, a tritium stored experiment was performed, the sample of protecting Argon gas which was between the tritium stored vessel and an outer closed container was extracted, and the tritium content was measured by using the method of proportional counter. Then, through conversion, the transient surplus after decay of the tritium out of the vessel was obtained. The analytical calculations data were compared with experimented measurement ones, which indicates the reasonability of theoretical analysis. The obtained laws that tritium permeation quantity changes with such parameters as time etc. are useful for theoretical design of tritium storied vessels.

The augmentation navigation system based on multi-source information fusion can significantly improve position accuracy, and the multi-source information is usually transmitted through VHF Data Broadcast . Aiming at the burst characteristics of VHF Data Broadcast, this article proposed a novel demodulation algorithm based on open-loop structure. When a VHF Data Broadcast burst is detected, the timing recovery should be finished first, and the value of cross-correlation between the timing-recovered signal and the local training symbol is calculated to complete the frame synchronization. Then, the data-aided and non-data-aided algorithms are used to estimate the frequency offset. Finally, the phase offset is estimated and the carrier synchronization is accomplished. The simulation results demonstrate that the proposed algorithm can quickly accomplished carrier synchronization without using feedback-loop structure, and the bit error rate is less than 10−4 when the signal-to-noise ratio is greater than 17 dB, which satisfy the requirement of receiving VHF Data Broadcast signals in augmentation navigation system. Therefore, the proposed algorithm can be used for receiving VHF Data Broadcast signals.

For the valorization of lignin, it is important and a great challenge to prevent the negative impact of phenolic hydroxyl (Ph-OH) on lignin pyrolysis by blocking the Ph-OH. Herein, lignin samples with different oxypropylation degree are prepared to investigate the effect of masking of Ph-OH on subsequent pyrolysis of softwood kraft lignin (SKL). It is found that the propylene oxide shows high selectivity (~94%) towards the oxypropylation of Ph-OH, which enhances the hydrogen to carbon effective ratio (H/Ceff) of SKL. In addition, the acquired oxypropylated lignins (OPLs) display a slight change in the structure compared to the original lignin except for their Ph-OH content. Moreover, the maximum degradation rate of lignin during heating significantly increases with the increase of oxypropylation degree. Noticeably, the relative content of low-oxygen aromatic compounds derived from lignin pyrolysis shows a positive correlation with the oxypropylation degree. More importantly, the oxypropylation of Ph-OH has a great contribution to improving the bio-oil yield from lignin pyrolysis. The reveal of the relationship between specific OPLs and pyrolysis behavior is of great significance for the highly selective conversion of lignin into high value-added specific compounds.

This study conducted on-site measurements of indoor volatile organic compounds (VOCs) in 251 occupied residences in China, with multiple visits throughout a whole year. Over 1000 samples were collected for measurement of VOCs in 8 cities, covering different climate regions. Overall, the concentrations of total VOCs (TVOCs) in occupied residences are in the range of 104–1151 μg/m3, with 20% of the samples over the Chinese standard of 600 μg/m3. A higher concentration was evident in the summer (mean = 705 μg/m3) compared to other seasons, especially winter (mean = 289 μg/m3). The TVOCs of residences in areas with central heating (severe cold regions and cold regions) are generally higher than those in areas without central heating. In winter, temperature was the dominant factor, whereas in summer, the building infiltration rate was the key factor influencing the indoor TVOC levels. The TVOCs concentration was also found to be directly proportional to the city economy level. Twenty-nine VOC species with a detection frequency higher than 40% were identified in all samples. Toluene is the most common VOC, with the highest detection rate (90%). The median concentration for a single VOC was between 1 and 14 μg/m3. Aldehydes were found to be the largest contributors to total VOCs in the Chinese residential buildings (mass proportion 22%), followed by benzene series (20%), alkenes (18%), and alkanes (15%). Aldehydes, especially long-chain saturated carbonyls, are likely to be the characteristic VOCs in the Chinese dwellings, with Chinese cooking as the major emission source. In addition, n-butane/i-butane showed maximum concentration in some residences (approximately 105 μg/m3 higher than other VOCs) owing to cooking fuel.

Poplar wood (Populus euramericana cv. “I-214”) was impregnated by pulse dipping at 0.7 MPa to 0.8 MPa for 30 min with a catalyst Ln∼SO42−/TiO2–SiO2, itaconic acid, and silica sol. Then, the modifier was cured within the wood micropores during in situ polymerization via kiln drying. The treated wood exhibited increased mechanical strength and decreased hygroscopicity. The modified samples were also characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results from the FTIR analysis indicated that the itaconic acid and SiO2 polymerized with the active groups of the wood cell wall. The TGA revealed that the crosslinking reaction between the modifier and wood enhanced the thermal stability of the composite. Lastly, the SEM results indicated the presence of the good interfacial adhesion in the wood modifier between the wood fibers and polymer.

Hydrophobic noncrystalline porous starch (NCPS) containing microporous and amorphous structures was prepared from native corn starch via heat treatment, solvent exchange, and alkyl ketene dimer (AKD) modification. Then, antibacterial packaging was produced by combining silver nanoparticles with the hydrophobic NCPS (hydrophobic NCPS/Ag) and employing this biobased coating as a layer on the base paper. The antibacterial activity, strength, and barrier properties of the hydrophobic NCPS/Ag-coated paper were measured. In addition, the fine porous surface of NCPS, the distribution of the silver nanoparticles in hydrophobic NCPS as well as the network structure of uncoated paper and coated paper were characterized by scanning electron microscopy. Meanwhile, the hydrophobicity of the corn starch, hydrophobic NCPS, uncoated paper, and coated paper were determined using water contact angles. The silver nanoparticles had a positive effect on the antibacterial activity against Escherichia coli and Staphylococcus aureus. The air permeability, oil resistance, water vapor transmission rate, water absorption, whiteness, tensile strength, and burst strength improved compared to the uncoated paper.

Non-crystal microporous starch (NCMS) containing microporous and amorphous structures was prepared from native corn starch by heat treatment and solvent exchange. NCMS can be used as fillers, coatings, and raw materials in the preparation of various denatured starch because of its specific surface area and amorphous region. However, the hydrophilicity of NCMS limits its applications in papermaking. Thus, in this study, NCMS was reacted with alkyl ketene dimer (AKD) to prepare hydrophobic NCMS (H–NCMS), which is more stable, and convenient for storage and use in surface sizing. The optimal preparation conditions were selected using single-factor tests. The product, which was prepared at 55 °C for 3 h with an AKD dosage of 80%, had a sizing degree of 67 s. Characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy confirmed that NCMS, H–NCMS, and sized paper were obtained. The thermal stability and hydrophobicity of the paper were measured using thermogravimetric analysis (TGA) and water contact angles, respectively. The results indicated that the sized paper has excellent thermal stability and hydrophobicity after surface sizing with 0.9% H–NCMS. Food wrapping paper with excellent strength and hydrophobicity was successfully prepared using H–NCMS and ultrasonic-assisted wheat straw pulp (UWP).