A practical model of quartz crystal microbalance (QCM) is presented, which considers both the Gaussian distribution characteristic of mass sensitivity and the influence of electrodes on the mass ...sensitivity. The equivalent mass sensitivity of 5 MHz and 10 MHz AT-cut QCMs with different sized electrodes were calculated according to this practical model. The equivalent mass sensitivity of this practical model is different from the Sauerbrey's mass sensitivity, and the error between them increases sharply as the electrode radius decreases. A series of experiments which plate rigid gold film onto QCMs were carried out and the experimental results proved this practical model is more valid and correct rather than the classical Sauerbrey equation. The practical model based on the equivalent mass sensitivity is convenient and accurate in actual measurements.
is a precious timber and fire-resistant tree species widely distributed in southern China. Currently, there is little knowledge related to its growth traits, especially with respect to molecular ...breeding. The lack of relevant information has delayed the development of modern breeding. The purpose is to identify probable functional genes involved in
growth through whole transcriptome sequencing. In this study, a total of 32,711 mRNAs, 525 miRNAs, 54,312 lncRNAs, and 1522 circRNAs were identified from 10
individuals containing different volumes of wood. Four possible regulators, comprising three lncRNAs, one circRNA, and eleven key miRNAs, were identified from the regulatory networks of lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA to supply information on ncRNAs. Several candidate genes involved in phenylpropane and cellulose biosynthesis pathways, including
,
, and
, and transcription factors, including
(
),
(
),
(
), and
, were identified to reveal the molecular regulatory mechanisms regulating the growth traits of
. The results not merely provide candidate functional genes related to
growth trait and will be useful to carry out molecular breeding, but the strategy and method also provide scientists with an effective approach to revealing mechanisms behind important economic traits in other species.
Pine resin, which typically consists of terpenoids, is a natural product used in various industrial applications. Oleoresin can be obtained from the xylem tissue by wounding the stem bark.
Pinus ...massoniana
(masson pine) is an important resin-tapping tree species that originated in southern China. Masson pines with different genetic backgrounds typically have different resin-yielding capacities (RYCs). However, the mechanisms underlying high resin yield in masson pines are unclear. The aim of this study was to identify the possible genetic regulation pathways and functional genes that influence the resin yield. In this study, we conducted transcriptomic and metabolomic studies of masson pine secondary xylem with high, medium, and low RYCs. A total of 230,068 unigenes and 3894 metabolites were identified from the tissue of the secondary xylem. Several differentially expressed regulation factors, including WRKY, bHLH, and ERF, and functional genes such as PKc and LRR-RLKs, were identified among these masson pines. The Kyoto Encyclopedia of Genes and Genomes pathways were mainly focused on diterpenoid biosynthesis, plant hormone signal transduction, and ABC transporters. Furthermore, integration of the transcriptomic and metabolomic data indicated that the PKc- and LRR-RLK-related regulatory and metabolic pathways may play critical roles in the biosynthesis of terpenoids. These above results improve our understanding of the biosynthesis mechanism of oleoresin in
P. massoniana
and facilitate further research work into the functional analysis of these candidate genes.
TH122; ...燃油雾化在航空发动机预混燃烧过程中起着至关重要的作用.为提高某航空燃油喷嘴的雾化特性,改进和优化其结构参数,采用流体体积(VOF)界面捕捉算法和正交试验设计相结合的方法,研究了喷嘴的内部流动及结构参数(扩张角、直线段长度、旋流槽升角、旋流槽个数)对雾化特性的影响规律.结果表明:旋流槽上的局部漩涡影响喷嘴内部燃油流动,通过改变旋流槽入口的结构形式消除局部压力损失;旋流槽个数对索特尔平均直径(SMD)的影响最为显著,扩张角是影响雾化锥角最大的因素,存在一个最优的旋流槽升角使油膜厚度最小,直线段长度对雾化特性的影响相对较小;当扩张角为60°、直线段长度为0.25 m m、旋流槽升角为45°、旋流槽个数为2时,优化效果最佳.优化后的喷嘴油膜厚度减小了43.68％,雾化锥角增加了3.70％,S M D减小了14.79％.
Terpenoids are the most important natural products collected from conifer species. However, the molecular mechanisms and core factors underlying terpenoid biosynthesis in Pinus massoniana remain ...unclear. To clarify these mechanisms, this study aimed to identify potential genes that might participate in the terpenoid biosynthesis of P. massoniana. In this study, single molecule real‐time (SMRT) sequencing and expression analysis were used to confirm the expression patterns of genes involved in the cones, immature needles, mature needles, immature branches, and mature branches of P. massoniana. A total of 31,331 lncRNAs and 71,240 mRNAs were identified from these organs, and the greatest number of differentially expressed genes (DEGs) was discovered between needles and branches. Weighted gene coexpression network analysis (WGCNA) classified all expressed genes into nine typical modules with 11 kinds of transcription factors (TFs), namely, AP2‐ERF, ARF, AUX‐IAA, C2H2, Dof, F‐box, SBP, WRKY, bHLH, bZIP, and GRAS, and seven kinds of functional genes, namely, ABC transporter, cellulose synthase (CesA), leucine‐rich repeats (LRR), cytochrome P450 (CYT P450), pathogenesis‐related protein (PR), terpene synthase (TPS), and chlorophyllase enzyme. A molecular network was constructed for hub genes, TFs, and functional genes in three modules. The potential function of eight candidate genes, including PmbHLH2, PmERF1, PmRGA, PmGAI, PmbZIP1, PmLOB1, PmMADS1, and PmMYB1, was validated through correlation analysis between terpenoid contents and expression levels, subcellular localization, and transcriptional activation activity, which provides us with probable regulators of terpenoid biosynthesis in conifers.
A mathematical model of loaded tooth contact analysis (LTCA) for cylindrical gear transmission with curvilinear-shaped teeth is established to analyze the loaded meshing characteristics of the ...transmission. Based on the forming principle of the gear transmission, a new method for establishing the tooth surface equation is proposed. A mathematical model of the geometric tooth contact analysis of the transmission was established, and the meshing parameters were calculated. Based on the meshing parameters, a mathematical LTCA model of the transmission was established by the integrated application of gear geometry, the finite element method, and elastic mechanics. In this study, the contact area distribution, contact stress distribution, load distribution and loaded transmission error (LTE) of the transmission were analyzed, and the loaded contact characteristics of the transmission were revealed. Furthermore, the influence of the gear pair design parameters on the loaded contact characteristics was discussed. The research results will provide a theoretical tool for the strength analysis, dynamic analysis, and gear tooth modification design of this transmission.
Fuel atomization plays an important role in premixed combustion of aero-engine. In order to improve the atomization characteristics of an aviation fuel nozzle and optimize its structural parameters, ...the volume of fluid (VOF) interface capture algorithm and orthogonal experimental design were used to study the influence of internal flow and structural parameters (expansion angle, length of straight section, rise angle of swirl groove, and number of swirl groove) on the atomization characteristics. The results show that the local vortex on the swirl groove affects the fuel flow in the nozzle, and the local pressure loss can be eliminated by changing the structure of the swirl groove inlet. The number of swirl grooves has the most significant effect on Sauter mean diameter (SMD), the expansion angle is the biggest factor affecting the atomization cone angle, there is an optimal swirl groove elevation angle to minimize the oil film thickness, and the length of straight section has relatively little effect on the
Due to the influence of liquid load, the equivalent resistance of in-liquid quartz crystal microbalance (QCM) increases sharply, and the quality factor and resonant frequency decreases. We found that ...the change in the resonant frequency of in-liquid QCM consisted of two parts: besides the frequency changes due to the mass and viscous load (which could be equivalent to motional inductance), the second part of frequency change was caused by the increase of motional resistance. The theoretical calculation and simulation proved that the increases of QCM motional resistance may indeed cause the decreases of resonant frequency, and revealed that the existence of static capacitance was the root cause of this frequency change. The second part of frequency change (due to the increases of motional resistance) was difficult to measure accurately, and may cause great error for in-liquid QCM applications. A technical method to reduce the interference caused by this effect is presented. The study contributes to the accurate determination of the frequency and amplitude change of in-liquid QCM caused by liquid load, which is significant for the QCM applications in the liquid phase.
Furfurylation is an effective and green method for wood or bamboo modification that can significantly improve its physical and mechanical properties and the resistance against biological ...deterioration and the attack of subterranean termites. To elucidate the effect of furfurylation on the physical and multiscale mechanical properties of bamboo, the conditions of the furfurylation process were modified to cause an independent variation of the physical and multiscale mechanical properties in differently-treated bamboo samples. This was achieved by impregnating bamboo samples with solutions containing 15%, 30%, 50%, or 70% furfuryl alcohol (FA) by either of the two impregnation processes, vacuum pressure (V-P) and soaking (S) impregnation, while applying different curing conditions (wet- or dry-curing). The physical properties we measured included the absorption rate, weight percent gain (WPG), swelling efficiency (SE), and anti-swelling efficiency (ASE); the macro-mechanical properties involved the modulus of rupture (MOR), the modulus of elasticity (MOE), parallel-to-grain compressive strength (CS), and tensile strength (TS); the micro-mechanical properties included the tensile strength of bamboo’s vascular bundle and hardness and the indentation modulus of bamboo’s fiber cell walls. Finally, the correlation between the different physical and mechanical properties of the modified bamboo samples was analyzed. The results indicate that V-P impregnation made bamboo more permissible for the penetration of FA, while wet-curing was more conducive to ensuring a high curing rate. The dimensional stability of the bamboo samples treated with a high FA concentration through V-P impregnation and of those furfurylated by the S-Wet process using either medium or high FA concentrations was significantly increased. However, the dimensional stability of the bamboo samples modified with either low or medium FA concentrations decreased in both dry and wet curing. In terms of mechanical strength, furfurylation had little effect on the macro- and micro-mechanical properties of bamboo and was slightly improved in comparison to untreated samples. The results also showed a positive correlation between the macro- and micro-mechanical strength of the modified bamboo samples and a significant negative correlation between the mechanical strength and ASE. In soaking impregnation, the WPG and ASE were positively correlated, while the WPG and CS were negatively correlated. Interestingly, the correlation between the mechanical properties and ASE was not significant. Finally, both V-P-Wet and S-Wet approaches can be recommended for bamboo furfurylation, the former being time-saving and having a high curing rate in FA resin while significantly improving the moisture absorption and mechanical strength of bamboo. The advantage of the latter process is simplicity, a high utilization rate of FA, and a significant improvement in the dimensional stability of bamboo.
Laser directed energy deposition (LDED), a highly promising metal additive manufacturing (AM) technology, has garnered widespread attention across various industries. However, local high-energy input ...during AM can generate residual stress (RS), which may cause deformation and even cracking of the parts. Due to the evolution of RS is influenced by temperature gradients, cooling rates and solid-state phase transformation(SSPT), accurately predicting RS remains challenging. To tackle this issue, a thermal-metallurgical-mechanical coupled model of 30CrNi2MoVA steel in LDED is established. To account for the influence of SSPT on the evolution of RS, the phase transformation kinetics model for 30CrNi2MoVA steel is developed based on thermal expansion experiments and integrated into mechanical computations. Using this model, the thermal cycle history, microstructure distribution and RS level of LDED fabricated parts are discussed in detail, and the accuracy of the model is verified through characterization experiments such as thermocouples, scanning electron microscopy and X-ray diffraction. The simulation results show that the RS of thin-walled parts is related to the scanning direction, and the maximum principal stress along the scanning direction is the highest. The microstructure of thin-walled parts is mainly composed of martensite with a small amount of bainite. Compared to models that do not consider SSPT effects, the overall stress magnitude of models that consider SSPT significantly decreases, and the surface RS state transitions from tensile stress to compressive stress. The proposed thermal-metallurgical-mechanical coupled model has the potential to accurately predict and understand the stress behavior and performance changes of 30CrNi2MoVA steel in LDED.
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