High-Throughput Additive Manufacturing of Continuous Carbon Fiber-Reinforced Plastic by Multifilament.

Additive manufacturing (or 3D printing) of continuous carbon fiber-reinforced plastics with fused deposition modeling is a burgeoning manufacturing method because of its potential as a powerful approach to produce lightweight, high strength and complex parts without the need for a mold. Nevertheless, it cannot manufacture parts rapidly due to low throughput. This paper proposes a high-throughput additive manufacturing of continuous carbon fiber-reinforced plastics by multifilament with reference to fiber tape placement. Three filaments were fed and compaction printed simultaneously by a robotic manufacturing system. The coupled thermal-mechanical model of the filament deformation during printing was developed to eliminate the initial interval between the filaments and improved mechanical properties. Furthermore, the mathematical relationship between filament deformation and printing parameters consisting of printing temperature, printing speed and roller pressure was proposed using response surface methodology with the line width as the response. The tensile tests demonstrate that the tensile properties of printed parts are positively correlated with the line width, but not infinitely improved. The maximum tensile strength and tensile modulus are 503.4 MPa and 83.11 Gpa, respectively, which are better than those obtained by traditional methods. Void fraction and scanning electron microscope images also reveal that the appropriate line width achieved by the reasonable printing parameters contributes to the high-throughput multifilament additive manufacturing of continuous carbon fiber-reinforced plastics. The comparison results indicate that the high-throughput multifilament additive manufacturing proposed in this paper can effectively improve the speed of continuous carbon fiber-reinforced plastics additive manufacturing without degrading the mechanical performance.

Spectral characteristics of the correlation between elemental arsenic and vegetation stress in the Yueliangbao gold mining.

Some soils in the Yueliangbao gold mining area have been contaminated by heavy metals, resulting in variations in vegetation. Hyperspectral remote sensing provides a new perspective for heavy metal inversion in vegetation. In this paper, we collected ground truth spectral data of three dominant vegetation species, Miscanthus floridulus, Equisetum ramosissimum and Eremochloa ciliaris, from contaminated and healthy non-mining areas of the Yueliangbao gold mining region, and determined their heavy metal contents. Firstly, we compared the spectral characteristics of vegetation in the mining and non-mining areas by removing the envelope and derivative transformation. Secondly, we extracted their characteristic identification bands using the Mahalanobis distance and PLS-DA method. Finally, we constructed the inverse model by selecting the vegetation index (such as the PRI, DCNI, MTCI, etc.) related to the characteristic band combined with the heavy metal content. Compared to previous studies, we found that the pollution level in the Yueliangbao gold mining area had greatly reduced, but arsenic metal pollution remained a serious issue. Miscanthus floridulus and Eremochloa ciliaris in the mining area exhibited obvious arsenic stress, with a large "red-edge blue shift" (9 and 6 nm). The extracted characteristic wavebands were around 550 and 680-740 nm wavelengths, and correlation analysis showed significant correlations between vegetation index and arsenic, allowing us to construct a prediction model for arsenic and realize the calculation of heavy metal content using vegetation spectra. This provides a methodological basis for monitoring vegetation pollution in other gold mining areas.

A label-free biosensor for selective detection of Gram-negative bacteria based on the oxidase-like activity of cupric oxide nanoparticles.

A label-free biosensor based on cupric oxide (CuO) nanoparticles was constructed for the selective detection of Gram-negative bacteria. CuO possesses oxidase-like activity and can catalyze the oxidation of o-phenylenediamine (OPD) to produce oxidized OPD, which has a fluorescence emission at 573 nm under excitation at 423 nm. The mechanism study suggests that the oxygen vacancies of CuO can activate the dissolved oxygen to form superoxide anions, which in turn oxidize OPD. Gram-negative bacteria can reduce part of Cu(II) in CuO to Cu(I) based on their copper homeostasis system, thus inhibiting the oxidation of OPD and decreasing the fluorescence intensity of the catalytic system. This principle was utilized to construct a biosensor to realize the selective detection of Gram-negative bacteria successfully. The biosensor exhibited a good linear correlation toward the logarithm concentration of three Gram-negative bacteria with R2 ≥ 0.985. It was applied to detect three Gram-negative bacteria in eggshell, Chinese cabbage, and the Pearl River water samples, with recoveries ranging from 92.4 to 107%. Moreover, a smartphone-based portable device was designed and fabricated to realize the on-site detection of bacteria. The results of the portable device were comparable to those of fluorescence spectrophotometry, suggesting that the portable device has tremendous potential in the on-site detection of bacteria.

Performance of 3D-Printed Continuous-Carbon-Fiber-Reinforced Plastics with Pressure.

Fused Deposition Modeling (FDM) has been investigated as a low-cost manufacturing method for fiber-reinforced composites. The traditional and mature technology for manufacturing continuous-carbon-fiber-reinforced plastics is Automated Fiber Placement (AFP), which uses a consolidation roller and an autoclave process to improve the quality of parts. Compared to AFP, FDM is simple in design and operation but lacks the ability to pressurize and heat the model. In this work, a novel method for printing continuous carbon-fiber-reinforced plastics with a pressure roller was investigated. First, the path processing of the pressure roller was researched, which will reduce the number of rotations of the pressure roller and increase the service life of the equipment and the efficiency of printing. Thereafter, three specimens were printed under different pressures and the tensile and bending strength of specimens were tested. The tensile strength and bending strength of specimens were enhanced to 644.8 MPa and 401.24 MPa by increasing the pressure, compared to the tensile strength and bending strength of specimens without pressure of 109.9 MPa and 163.13 MPa. However, excessive pressure will destroy the path of the continuous carbon fiber (CCF) and the surface quality of the model, and may even lead to printing failure.

Selectively Enhanced 3D Printing Process and Performance Analysis of Continuous Carbon Fiber Composite Material.

Aiming at the limited mechanical properties of general thermoplastic 3D printed models, a 3D printing process method for selective enhancement of continuous carbon fiber composite material is proposed. Firstly, the selective enhanced double nozzle working mechanism and crafts planning process are put forward. Then, based on the double nozzle carbon fiber 3D printing device, test samples are printed by polylactic acid (PLA) and carbon fiber material, and the test samples are enhanced by inserting layers of continuous carbon fiber material. The performance test of the samples is carried out. Experiment results show that when the volume fraction of continuous carbon fiber material increases gradually from 5% to 40%, the tensile strength increases from 51.22 MPa to 143.11 MPa. The performance improvement curve is fitted through experimental data. Finally, field scanning electron microscopy is used to observe the microscopic distribution of continuous fibers in the samples. The results of the research lay the foundation for the performance planning of 3D printed models.

[Observation on the receiving sensibilities of the points on the hand's six channels for vibromusic sound wave].

OBJECTIVE: To understand the receiving sensibility of the points on the hand's six channels for music sound wave in the healthy persons, so as to provide experimental basis for exploring the mechanism of music treatment. METHODS: By the radiating and receiving sound wave system, the total receiving music sound (RMS) power of the music sound wave were measured at the points of the hand's six channels and non-acupuncture in 34 healthy undergraduates. RESULTS: There was the specific receiving sensibility at Taiyuan (LU 9). The total RMS power of the music sound wave at Daling (PC 7) and Shaohai (HT 3) in the female was stronger than that in the male. CONCLUSION: There is the difference in the receiving sensibility of the music sound wave at the different acupoints of different channels.

[Advances of studies on the biophysical characteristics of channels and acupoints].

OBJECTIVE: To summarize recent studies on the biophysical characteristics of meridians and acupoints, so as to provide a basis and thinking for scientific studies. METHODS: Twenty-nine papers about biophysical characteristics of meridians and acupoints were reviewed from studies of electricity, heat, sound, light, magnetic and radionuclide. RESULTS: The biophysical characteristics of meridians and acupoints have been proved in different domains, and meridians and acupoints objectively exist. CONCLUSION: Scientific studies on the biophysical characteristics of meridians and acupoints have vast vistas.

[Experimental study on conduction of Gong tonality vibromusic sound wave in the healthy human body].

OBJECTIVE: To study the conduction of Gong tonality vibromusic sound wave along meridians in healthy human body, and investigate differences of the sensitivity of different meridians and genders to this vibromusic message. METHODS: Emit the Gong tonality music signal under the water and then investigate the responses of different acupoints and control points at the tissue of the same level to the vibromusic sound wave. RESULTS: There were differences of sensitivity to music waves at source acupoints on the foot, sensitivity of Zusanli (ST 36) was significantly higher than its control point (P < 0.05), and there was difference between genders in the sensitivity of Sanyinjiao (SP 6) and Yinlingquan (SP 9) to music sound wave. CONCLUSION: Gong tonality vibromusic sound wave can conduct along meridians in healthy human body, and there are differences between different meridians and different genders in the sensitivity to the music sound wave.