Review of ultrasonic testing technology for bonding interfaces of solid rocket motors

The internal structure of heavy-calibre rocket engines, as used in army ordnance, is a multi-interface bonding structure. The bonding quality between layers has an important impact on safety when shooting, so it must be tested before use in the field. In this paper, the progress of research into ultrasonic testing (UT) technology for the interface bonding of solid rocket motors is reviewed from the two aspects of testing methods and signal processing technology. Future work is also discussed.

A Simple and Low-Cost Method for Fabrication of Polydimethylsiloxane Microfludic Chips

The conventional fabrication methods for enrichment microfluidic devices require cleanroom, which are costly and time-consuming. Developing a facile and low-cost method to fabricate microfluidic chips could stimulate the progress of the applications of those chips. Here, we present an easy method for fabrication of a complete PDMS (Polydimethylsiloxane) microfluidic chip used for ion and protein enrichment. The method consists of three main fabrication steps: PDMS microchannels ablation by co2 laser, nation membrane deposition, and oxygen plasma assist bonding under pressure. To fabricate a desired microchannel, the laser ablation parameters, containing laser power and ablation speed, were analyzed. The parameters for oxygen plasma assist bonding were also investigated to improve the bonding quality of the chips (low dimension loss and high bonding strength). The following Rhodamine B enrichment tests demonstrate that the presented method allows fabrication of microfluidic chips with precise dimensions and leakage free.

Research on Interlayer Bonding Quality Control Method of Dam Concrete Based on Equivalent Age

Interlayer bonding quality is the key to the stability and durability of dam concrete. In this study, interlayer splitting tensile strength, relative permeability coefficient, and electric flux of dam concrete at different temperatures were tested. The relationships between equivalent age and strength coefficient, relative permeability coefficient ratio, and electric flux ratio were established. Meanwhile, a comprehensive early-warning and control system of dam interlayer bonding quality based on the above relationships was proposed. The results showed that the interlayer mechanical properties, impermeability, and anti-chloride ion permeability of dam concrete decreased with the increase of temperature. Moreover, the equivalent age was linearly correlated with strength coefficient, relative permeability coefficient ratio, and electric flux ratio of concrete. The correlation coefficients were 0.986, 0.973, and 0.924, respectively. In addition, the interlayer bonding quality of dam concrete can be effectively controlled by the early-warning system established according to the relationship between equivalent age and interlayer properties parameters.

Prenatal Attachment pada Kehamilan Remaja dengan Gangguan Penyesuaian dan Retardasi Mental Berat

Prenatal attachment is an abstract and unidirectional bond between parents and the fetus that develops during pregnancy. It is closely associated with how the mother utilizes her abilities and knowledge to organize and perform the duties related to her maternal role attainment. We report a case of 15 years old girl admitted to the emergency room with an official request of visum et repertum in January 2018 due to becoming suspected sexual violence victim. The history of present illness revealed a 15 y.o. girl G1P0A0, singleton, at 34-36W Estimated Gestational Age with condyloma acuminata. During her pregnancy, she described relatively negative feelings about her pregnancy including shame, anxiety, and anger. She felt lack of energy and motivation since she became aware of her pregnancy, therefore spent her most of her time on the bed. Her IQ-test showed a profound intelligence rate followed by a total score of Strength and Difficulty Questionnaire (SDQ) 16, and scored low in Prenatal Attachment Inventory (PAI) at 31. We concluded that PA scoring can be utilized as a predictor of mother-infant bonding quality after birth, thus the instrument will be beneficial as initial screening before choosing appropriate management for vulnerable population mother.

Possibility of Use of NCC-Reinforced Melamine-Urea- Formaldehyde Adhesive in Plywood Manufacturing

The possibility of using nanocellulose (NCC) as a filling substance for melamine-urea-formaldehyde (MUF) adhesive was investigated for the process of manufacturing plywood. The adhesive mixtures were prepared with various nanocellulose concentrations. The amount of introduced filler had a significant effect on both resin and plywood characteristics. Fourier transform infrared spectroscopy (FTIR) did not show any major changes between experimental and reference variants. The viscosity of resin increased after the introduction of nanocellulose. The addition of NCC in the amount of 5 g and 10 g per 100 g of solid resin led to an improvement in bonding quality, modulus of elasticity and bending strength. Further increase of NCC concentration caused a deterioration of manufactured plywood properties. In summary, the addition of proper amount of nanocellulose resulted in manufacturing plywood with improved properties.