Improvement of Interlaminar Fracture Properties of Out of Autoclave Manufactured Carbon Fiber Reinforced Polymers Using Multi-Walled Carbon Nanotubes

The present study aims to the development of Out of Autoclave (OoA) Carbon Fiber Reinforced Polymers (CFRPs) with increased interlaminar fracture toughness by using MWCNTs. The introduction of MWCNTs into the structure of CFRPs has been succeeded by using carbon nanotube-enriched sizing agent for the pretreatment of the fiber preform using an in-house developed methodology that can be easily scaled up. The positive effect of the proposed methodology on the interlaminar fracture toughness of the CFRP laminate was assessed by the increase of Mode I and Mode II interlaminar fracture toughness of the composites. Different wt% MWCNTs concentrations were used (namely 0.5%, 1%, 1.5% and 2.5%). It was found that the nanomodified composites exhibit a significant increase of the interlaminar critical strain energy release rate GIC and GIIC of the order of 103% and 62% respectively, in the case of 1.5 wt% MWCNTs weight content. Scanning Electron Microscopy (SEM) of the fracture surfaces of CFRP samples revealed the contribution and the associated synergistic mechanisms of MWCNTs to the increase of the crack propagation resistance in the case of nano-modified CFRPs compared to the reference material.

Effects of Lay-up Types of Out-of-autoclave Prepregs on Preparation Quality of L-shape Composite Laminates

Effects of layer quantities and stacking sequences on L-shape composite manufacturing qualities in using OOA(out-of-autoclave)prepregs were studied.The mechanisms of air evacuated in 5 kinds of lay-ups were revealed by image analysis of cut surfaces and thickness measurements.Results show that air in OOA prepregs is evacuated in two ways.Most of the air is forced out of layers directly by vacuum before air accesses in prepregs closed.Very little entrapped air moves perpendicularly to outer layers under hydrostatic resin pressure.When a laminate contains less than 16 layers,voids can hardly be found in layers.When a laminate contains more than 16 layers,voids cannot be expelled completely during the window of vertical movement.As for stacking sequences,the synergetic effect of slip function and nest function determines the thickness and voids content of laminates.Results show that the average of single layer thickness of unidirectional layers is the lowest,and the average of single layer thickness of quasi-isotropic layers is the highest.The voids content of quasi isotropic is the highest,which is consistent with the theoretical analysis.

基于OOA优化BP神经网络的光伏发电功率预测

准确预测光伏发电功率是保障电网平稳运行的关键环节,但由于光伏发电系统输入变量较多,造成标准BP神经网络系统对发电功率预测的精度不理想。基于OOA优化BP神经网络的预测模型(OOA-BP),可以提高预测精度。将总辐照度、直射辐射、散射辐射、气温、气压和湿度6种类型数据作为OOA-BP神经网络预测模型的输入量,并将其预测结果与标准BP神经网络进行对比。结果表明:相较于标准BP神经网络模型,OOA-BP神经网络预测模型通过优化阈值和权值,可以有效提升光伏发电功率的预测精度和预测效率。

Leaching of a copper flotation concentrate with ammonium persulfate in an autoclave system

The leaching behavior of a copper flotation concentrate was investigated using ammonium persulfate （APS） in an autoclave systee. The decomposition products of APS, active oxygen, and acidic medium were used to extract metals from the concentrate. Leaching experiments were performed to compare the availability of APS as an oxidizing agent for leaching of the concentrate under atmospheric conditions and in an autoclave system. Leaching temperature and APS concentration were found to be important parameters in both leaching systems. Atmospheric leaching studies showed that the metal extractions increased with the increase in APS concentration and temperature （up to 333 K）. A similar tendency was determined in the autoclave studies up to 423 K. It was also determined that the metal extractions decreased at temperatures above 423 K due to the passivation of the particle surface by molten elemental sulfur. The results showed that higher copper extractions could be achieved using an autoclave system.

Synthesis and Microstructure Analysis of Autoclaved Aerated Concrete with Carbide Slag Addition

Synthesis of autoclaved aerated concrete （AAC） has been carried out with carbide slag addition, and the carbide slag could be used as a main material to produce the AAC with the compressive strength about 2 MPa and the density below 0.6 g.cm-3. In this study, quartz sand acted as frame structure phase in the matrix, and quartz addition also influenced the Si/Ca of starting material. Tobermorite and CSH gel were formed readily at 62%, which seemed to enhance the compressive strength of samples. Curing time seemed to affect the morphology of phase produced, and specimen with the plate-like tobermorite formed at 10 h appeared to have a better compressive strength development than the fiber-like one at 18 h. The higher curing temperature seemed to favor the tobermorite and CSH gel formation, which also exerted a significant effect on the strength development of the samples. On the micro-scale, the formed CSH gel was filled in the interface of the matrix, and the tobermorite appeared to grow in internal-surface of the pores and interstices. The tobermorite or/and CSH formation seemed to densify the matrix, and therefore enhanced the strength of the samples.

Variation law of gas holdup in an autoclave during the pressure leaching process by using a mixed-flow agitator

The multiphase reaction process of pressure leaching is mainly carried out in the liquid phase. Therefore, gas holdup is essential for the gas–liquid–solid phase reaction and the extraction rate of valuable metals. In this paper, a transparent quartz autoclave, a six blades disc turbine-type agitator, and a high-speed camera were used to investigate the gas holdup of the pressure leaching process. Furthermore, experiments determining the effects of agitation rate, temperature, and oxygen partial pressure on gas holdup were carried out. The results showed that when the agitation rate increased from 350 to 600 r/min, the gas holdup increased from 0.10% to 0.64%. When the temperature increased from 363 to 423 K, the gas holdup increased from 0.14% to 0.20%. When the oxygen partial pressure increased from 0.1 to 0.8 MPa, the gas holdup increased from 0.13% to 0.19%. A similar criteria relationship was established by Homogeneous Principle and Buckingham's theorem. Comprehensively, empirical equation of gas holdup was deduced on the basis of experimental data and the similarity theory, where the criterion equation was determined as ε=4.54×10^(-11)n^(3.65)T^(2.08)P_g^(0.18). It can be seen from the formula that agitation rate made the most important impact on gas holdup in the pressure leaching process using the mixed-flow agitator.

Preparation of New Cementitious System using Fly Ash and Dehydrated Autoclaved Aerated Concrete

We experimentally studied the interaction between pozzolanic material（fly ash） and dehydrated autoclaved aerated concrete（DAAC）. The DAAC powder was obtained by grinding aerated concrete waste to particles fi ner than 75μm and was then heated to temperatures up to 900 ℃. New cementitious material was prepared by proportioning fly ash and DAAC, named as AF. X-ray diffraction（XRD） was employed to identify the crystalline phases of DAAC before and after rehydration. The hydration process of AF was analyzed by the heat of hydration and non-evaporable water content（Wn）. The experimental results show that the highest reactivity of DAAC can be obtained by calcining the powder at 700 ℃ and the dehydrated products are mainly β-C2 S and CaO. The cumulative heat of hydration and Wn was found to be strongly dependent on the replacement level of fl y ash, increasing the replacement level of fl y ash lowered them in AF. The strength contribution rates on pozzolanic effect of fl y ash in AF are always negative, showing a contrary tendency of that of cement-fl y ash system.

Impermeability Research of Autoclaved Propylene Oxide Sludge Shell-aggregate Concrete

We aimed to reuse the propylene oxide sludge(POS).Propylene oxide sludge shell-aggregate(POSS-A)and propylene oxide sludge gradient shell-aggregate(POSGS-A)whose main hydrated phase is tobermorite were successfully manufactured by the hydrothermal synthesis of POS and silica materials under the condition of autoclaved(180℃,1.0 MPa)curing.Influences of pre-wetting time of coarse aggregate and pressure application mode on the different concretes were investigated.The experimental results show that the concrete with POSS-A as coarse aggregate(POSS-A concrete),the concrete with POS gradient shell-aggregate as coarse aggregate(POSGS-A concrete),sintered aggregate concrete and common concrete,all have excellent impermeability performance whatever the pre-wetting time of coarse aggregate is 0.5 h or 24 h,and the pre-wetting time of coarse aggregate has a negligible influence on the concrete.The influence degree of pressure application mode on the impermeability performance of the sintered aggregate concrete is the greatest among three kinds of concrete,which has a negligible influence on impermeability performance of the other concretes.POSGS-A can be used as a green building light aggregate in hydraulic concrete.

A Review on the Utilization of Waste Material for Autoclaved Aerated Concrete Production

Autoclaved aerated concrete(AAC)has become more attractive due to its excellent and environmental-friendly properties in building construction.AAC is relatively lightweight,possesses lower thermal conductivity,higher heat resistance,lower shrinkage,and fasten construction than normal concrete.AAC is a combination of silica sand,cement,gypsum,lime,water,and an expansion agent.To improve its physical and mechanical properties and reduce its production cost,tremendous innovations where waste materials were utilized as partial replacement of AAC materials were done.This paper is intended to present the literature on the utilization of waste materials as a means of a partial replacement in AAC materials to enhance its physical and mechanical properties and thermal performance.The physical properties such as microstructure and mechanical properties such as density,compressive strength,water absorption are presented to classify the investigation that has been done in such innovations.Apart from that,the discussion on innovations to improve its thermal performance was also presented.Based on the review,an increase of AAC application causes much waste at construction sites and recycling concrete waste powder into wall concrete;particularly,an AAC was not frequently practiced in construction.

Relationship between Structural Characteristics of Fly Ash and Reactivity under Autoclave Curing

The reactivity of autoclaved materials is conventionally estimated by their chemical composition. In this paper, after determining the chemical composition of various types of fly ash, a series of new tests which included X-ray Diffraction (XRD), infrared spectral analysis (IR) and bound water testing, were applied to investigate the performance of autoclaved fly ash products. The relationship between the infrared spectral analysis of Si-O wavenumber (about 1 100 cm-1) and its autoclaved chemical reactivity, and compressive strength of its autoclaved samples, is analyzed. The results show that fly ash with a lower wavenumber will have stronger autoclaved chemical reactivity and higher compressive strength for its autoclaved sample. Thus, the Si-O stretching vibration wavelength can be used to estimate autoclaved chemical reactivity of fly ash, so as to control the quality of fly ash to be autoclaved, and to predict the compressive strength of autoclaved fly ash products.

Kinetics of Autoclave Curing Process on Autoclaved Aerated Concrete with Magnetite Tailings

Lightweight and energy saving autoclaved aerated concrete(AAC) acting as a newbuilding material were prepared by using magnetite tailings from iron ore as main rawmaterials,and the purpose of comprehensive utilization of tailings resources was to improve their utilization efficiency.The effects of curing system on AAC product performance were discussed.The autoclave curing reaction kinetics was studied as well as the generated amount of hydration product trends over autoclave curing temperature and time were analyzed.The results indicated that the properties of AAC was in accordance with Chinese national standard the A3.5 B06 class of GB/T11968-2006 by prepared from magnetite tailing as the main rawmaterials.Meanwhile,autoclave curing process was controlled by the diffusion velocity through the products ' layers of reactants,and the apparent activation energy of autoclave curing process was 19.269 k J/mol.Compressive strength of aerated concrete is improved by mutual cementation between the appropriate amount of calcium silicate hydrate and tobermorite crystal.

Thermal Insulation and Strength of Autoclaved Light Concrete

The primary objective of this study was to develop an autoclaved light concrete （ALC） material with ultra-thermal insulation property and to investigate the relationship between its physical characteristics and mechanical properties. Through tests of dry bulk density and compressive strength, relationship of physical characteristics and mechanical properties of samples were studied, resulting in a material with ultra-thermal insulation property. Scanning electron microscope （SEM） and energy-dispersive X-ray spectroscopy （EDX） were applied to analyze the micro-morphology and elemental composition of samples. To identify the product phases, X-ray diffraction （XRD） was engaged. The test results showed that compressive strength and thermal coefficient were reduced with the increasing of aluminum powder within the mixtures. As a result the optimal thermal coefficient and compressive strength of samples were improved to 0.061 W/（m·k） and 1.2 MPa, respectively. SEM, EDX and XRD analyses showed that calcium silicate hydrate and tobermorite crystal were main resultant phases.

Development of in-situ Micro-Raman spectroscopy system for autoclave experimental apparatus

We developed a set of in-situ Micro-Raman spectroscopy system for autoclave experimental apparatus because of the scientific significance of in-situ Micro-Raman spectroscopy system under the high-pressure hydrothermal condition.We used this system to measure the Raman spectrum of water-fluid and quartz crystal at the temperature ranging from 125 to 420℃.The signal-tonoise ratio of the Raman signal is good.

Effect of Autoclave Sterilisation on the Dimensional Stability and Tear Strength of Three Silicone Impression Materials

Objectives: There is a risk of spreading infectious material via non-sterile impressions. The aim of this study was to compare the effect of autoclave sterilisation on dimensional stability and tear strength of impression materials. Methods: Twenty-four specimens were produced using a standard ruled test block for each of three impression materials (Affinis, Aquasil and Speedex) to test dimensional stability. Thirty tear strips for each material were prepared for the tear test (ISO 34-1). Specimens were randomly allocated to 3 different groups (autoclaved, disinfected or untreated). A non-contact scanner was used to analyse dimensional change and a universal testing machine was used to determine tear strengths. Results: There were no significant differences in the test dimensions measured for any of the three impression materials following autoclave treatment compared to the disinfected or untreated control groups. The tear strengths were not adversely affected by autoclave sterilisation at 134°C. Conclusion: These addition and condensation-cured silicone impression materials can be steam autoclaved without adverse effects on dimensional accuracy or tear strength.

Influence of Polycarboxylic-type Admixture on the Strength of Autoclaved Aerated Concrete

The influence of polycarboxylic-type admixture on the strength of autoclaved aerated concrete（AAC） was investigated. The flexural strength and compressive strength of AAC with polycarboxylic admixture（PA） were tested. The microstructure of AAC reinforced by PA was analyzed using scanning electron microscopic（SEM） methods. The crystal structure analysis of AAC with PA was also carried out using X-ray diffraction（XRD）. The results showed that the compressive strength and flexural strength of AAC were increased by 43.9% and 42.8%, respectively, when 1.5wt% of PA was mixed. In addition, the dosage of admixture influenced the reinforcing effect. Admixture affected pore structure and surface characteristic of the products in autoclaved curing process and improved the formation of high crystallite tobermorite which led to the enhancement of the compressive and flexural strength of AAC.

Influence of the Process of Worker on the Mechanical Properties of Carbon Fiber Reinforced Plastic Molded by Autoclave

The present study aims to investigate the difference of the operation process and the significant mechanical properties between expert workers and beginner workers clearly. The influence of the performance of the carbon fiber reinforced plastic (CFRP) molds made by subjects with difference skill level was discussed. Subjects were allowed to choose their process and molding tools. Subject A had 13 years,and subject B had 1 year of professional experience.The time spent usage of tools and process was recorded by a video camera used for analysis and comparison. Mechanical properties assessed in this study include tensile,compressive and Izod impact properties. The working time analysis shows that subject A needs short time for each process. On the other hand,subject B takes twice time to work for each process compared with subject A. From the surface and cross-section observation, it was found that the molding made by subject B had wrinkles all over and the disorderly inter-layer direction; on the contrary,the wrinkles on the molding surface of subject A are barely,and the inter-layer direction of which are more orderly. The results of tensile and Izod impact tests show that the surface winkles have little influence on the mechanical properties of the molding. According to the compression test and failure structure analysis in edge corner part,it was found that it had a great influence on the compression mechanical properties of the sample belonging to different subjects with different experience.

Experimental Study on Improving Seismic Behavior of Load-Bearing Masonry Wall Made of Autoclaved Aerated Concrete

To investigate the seismic behavior of autoclaved aerated concrete load-bearing masonry wall(AACLMW), a piece of control block wall without constructional measures and five pieces of block walls with different constructional measures were tested under low reversed cyclic loading which imitated low to moderate earthquake force. The seismic behavior of AACLMW with different constructional measures in terms of failure mode, hysteretic curve, deformation capacity and displacement ductility was studied and compared with that without constructional measures. The experimental results indicate that the constructional measures comprising constructional columns and horizontal concrete strips are effective for improving the seismic behavior of AACLMW. The study in this paper can provide a reliable experimental basis for further analysis and engineering application of AACLMW in the future.

Nano-treatment of Autoclaved Aerated Concrete Waste and Its Usage in Cleaner Building Materials

Autoclaved aerated concrete waste(AACW)was used as a raw material to prepare nucleation seed for acceleration of Portland cement.Nano AACW seed with median particle size of 324 nm was prepared by wet grinding method.Both the electrical conductivity and pH value of nano AACW suspension were obviously improved.Both the setting times and intensity of the main hydration heat peak were promoted by nano AACW,indicating the possibility of AACW suspension as nucleation seed.The early age compressive strength before 3 days was also clearly improved by nano AACW,with no negative effect on the late age strength.Furthermore,the reduced CH content with dosage of nano AACW indicates that nano AACW not only plays a role of nucleation seed in cement hydration,but also has a certain pozzolanic reaction.

Utilization of Dredged River Sediment in Preparing Autoclaved Aerated Concrete Blocks

In this study,the dredged river sediment,soft texture and fine particles,is mixed with other materials and transformed into eco-friendly autoclaved aerated concrete(hereinafter referred to as AAC)blocks.The results indicated the bricks produced under the conditions of 30%–34%dredged river sediment,24%cement,10%quick lime,30%fly ash,2%gypsum and 0.09%aluminum powder with 0.5 water to material ratio,2.2 MPa autoclave pressure and 6 h autoclave time,the average compressive strength of 4.5 MPa and average dry density of 716.56 kg/m³were obtained,the two parameters(strength&density)both met the requirement of national industry standard.At the same time,the contents of dredged river sediment,cement,lime,fly ash,gypsum and aluminum powder were 15%,48%,20%,15%,2%and 0.09%,respectively,and the non-AAC block made of 0.5 water to material ratio,the average compressive strength of 3.1 MPa and average dry density of 924.19 kg/m³were obtained,the two parameters(strength&density)also met the requirement of national industry standard.In addition,the AAC block’s phase composition and morphology were micro-analyzed by SEM and XRD,the main substances in AAC block were found to be tobermorite and CSH,Among them,the chemical bond between Si-O-Si and Al-O-Al is broken,Al-O-Si is regenerated,Al substituted tobermorite with better strength is formed,and the compressive strength of AAC is further improved.

Morphological effects of autoclaved diet on the myenteric neurons of rats

AIM:To evaluate the effect of autoclaved diet on the jejunum neurons of the myenteric plexus of rats during their growth.METHODS:The experimental groups were made up of rats going through weaning whose mothers received either an autoclaved or a non-autoclaved diet during gestation and lactation,and rats that were fed the same diet as their mothers during the post-weaning period.In order to measure the neurons'body profile and to quantify the number of neurons per area,preparations were stained by the nicotinamide adenine dinucleotide-diaphorase method.RESULTS:No significant changes were observed in rats'body weight or in the number of neurons regardless of the diet used(P>0.05) .There was a decrease in the jejunum-ileum length in rats treated with an autoclaved diet(P<0.05) .An increase in the neuronal cross-sectional area was seen in rats that had received the autoclaved diet,an effect that was significant for animals undergoing weaning.In addition,all observed factors showed significant differences when related to the age of the animals.CONCLUSION:The autoclaved diet did not alter the quantity of neurons,but increased their cell body area,suggesting changes similar to those observed in protein deficiency.