Viet Tri University of Industry

<title>Abstract</title> In this study, a bio-based polyamide 11 (PA11) composite reinforced with alkali-treated ramie fiber (tRF) was successfully fabricated by hot pressing. To identify optimal treatment conditions, ramie fibers were subjected to alkaline treatment using NaOH concentrations of 0%, 1%, 3%, and 5% by weight. Treatment of ramie fibers with a 3% NaOH solution led to a remarkable 137.5% increase in tensile strength compared to untreated fibers, alongside improved surface characteristics and fiber purity. As a result, the PA11/tRF composite substantially improved overall performance. Specifically, tensile strength increased by 131.45% and flexural strength by an impressive 390.51% compared to neat PA11. Advanced characterization techniques, including dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), confirmed strong interfacial interactions and enhanced thermal stability of the PA11/ramie fiber composite. These outstanding results demonstrate the effectiveness of alkali-treated ramie fibers in reinforcing PA11, establishing the PA11/tRF composite as a strong candidate for sustainable, high-performance, and eco-friendly material applications.

The proliferation of unmanned aerial vehicles (UAVs) has raised significant security and surveillance challenges, necessitating high-precision direction-finding (DF) techniques for effective detection and tracking. This paper presents a novel approach to UAV direction finding using an antenna array of 16 log-periodic elements, designed for wideband operation and accurate direction-of-arrival (DOA) estimation. The system utilizes an RF switch to sequentially sample signals from each antenna pair, thus reducing hardware requirements. An advanced DF algorithm, combining phase center concept and correlative interferometer, is employed to achieve accurate DOA estimation. Experimental results demonstrate the system’s ability to accurately determine the direction of UAVs under different scenarios, validating its robustness and applicability for real-world operation.

This study reports the findings on the use of a multi-criteria decision-making (MCDM) method to determine the optimal dressing mode for surface grinding of Hardox 500. This study investigates three objectives: surface roughness (SR), material removal rate (MRR), and wheel life (Lw). Additionally, five dressing variables were analyzed: non-feeding dressing nn, fine dressing depth df, fine dressing times nf, rough dressing depth dr, and rough dressing times nr. The Multi-Attribute Utility Theory (MAUT) method was applied to solve the MCDM problem, and the Entropy technique was used to ascertain the criterion weights. Furthermore, 16 experimental runs were designed and conducted using the L16 (4^4 x 2^1) design type. The issue regarding MCDM has been assessed. The investigation's findings indicate that option No. 7, defined by the input parameters dr = 0.02 (mm), nr = 3, df = 0.05 (mm), nf = 3, and nn = 0, represents the optimal dressing mode.

Nghiên cứu này tập trung vào việc tổng hợp nano bạc sinh học từ dịch chiết cây Thành ngạnh (Cratoxylum pruniflorum) và ứng dụng của chúng trong nhuộm tóc bạc. Mục tiêu của nghiên cứu là phân tích các đặc tính vật lý của nano bạc và khả năng ứng dụng trong nhuộm tóc. Nano bạc được tổng hợp thông qua phản ứng khử Ag+ từ dung dịch AgNO3 bằng dịch chiết cây C. pruniflorum. Các phương pháp phân tích bao gồm quang phổ UV-Vis, phổ nhiễu xạ tia X, phổ hồng ngoại biến đổi Fourier, kính hiển vi điện tử truyền qua và kính hiển vi điện tử quét được sử dụng để đánh giá các đặc tính của nano bạc. Kết quả quang phổ UV-Vis chỉ ra đỉnh hấp thụ tại 437 nm, đặc trưng cho nano bạc. Phổ nhiễu xạ tia X xác nhận cấu trúc lập phương tâm mặt của nano bạc. Phổ hồng ngoại biến đổi Fourier cho thấy các nhóm O-H, C=O, C-H và C-O từ dịch chiết tham gia vào quá trình khử và ổn định hạt nano. Hình ảnh chụp kính hiển vi điện tử truyền qua và hiển vi điện tử quét chỉ ra các hạt nano bạc hình cầu, kích thước từ 5-40 nm với phân bố kích thước đồng đều. Khả năng nhuộm tóc bạc bằng dung dịch nano bạc cho thấy màu đen đồng nhất và không bị phai sau 20-30 lần gội. Thử nghiệm mẫn cảm trên da chuột nhắt trắng Swiss không phát hiện viêm nhiễm hay kích ứng, chứng minh tính an toàn của sản phẩm. Những kết quả này mở ra triển vọng ứng dụng nano bạc từ dịch chiết cây Thành ngạnh trong các sản phẩm nhuộm tóc an toàn.

This article presents the results of an optimization study on the determination of the best input parameters for the internal grinding process when processing cylindrical-shaped parts of SKD11 tool steel. For this purpose, three Multi-Criteria Decision Making (MCDM) methods including the Evaluation based on Distance from Average Solution (EDAS), Multi-Attributive Border Approximation Area Comparison (MABAC), and Multi Attribute Utility Theory (MAUT) were used to solve the MCDM problem, while the entropy method was applied to find the criteria weights. Three objectives, namely the Surface Roughness (SR), Material Removal Rate (MRR), and wheel life (Tw), were also investigated. Six input factors, involving the coarse dressing depth (ar), coarse dressing times (nr), fine dressing depth (af), fine dressing times (nf), non-feeding dressing (n0), and dressing feed rate (Sd), were examined. Additionally, the Taguchi method with the L16 (44+22) design and the Minitab R19 program were deployed to design this study’s experiment and investigate its outcomes. The MCDM work was successfully solved and the best process factors are proposed.

The TEACCH method (Treatment and Education of Autistic and Related Communication Handicapped Children) has been proven effective in helping children with Autism Spectrum Disorder (ASD) develop early reading skills, particularly in recognizing Vietnamese letters. This study applied the TEACCH method to a 5-year-7-month-old child with ASD in Hai Phong. Over 8 weeks, the child participated in structured activities designed for letter recognition, supported by visual aids and clear schedules. The results indicated significant improvement in the child’s ability to identify letters, maintain attention, and engage in learning activities. Additionally, the child became more independent in completing tasks. The results of this case study contribute to demonstrating the feasibility and effectiveness of the TEACCH method in supporting children with ASD in preparing for the process of learning to read and write, as well as better preparing them for the transition to the next educational level.

This study investigated the acute and repeated 28-day dose toxicity profiles of Bacillus clausii M31, isolated from children's feces, in Swiss rats and New Zealand rabbits. To investigate acute toxicity, rats were given varied doses of B. clausii M31 (1×1011CFU/mL, 3×1011CFU/mL, and 5×1011CFU/mL) orally once daily for 14days, in accordance with OECD recommendations No. 423. To evaluate toxicity, rabbits were given either a low dosage (1×1011CFU/mL) or a high dose (5×1011CFU/mL) during a 28-day period using the OECD Test Guideline 407 protocol. Neither death nor significant abnormalities were observed in the rats during the experiment. The microscopic examination of key organs revealed no substantial changes in organ morphology. Furthermore, analyses of serum biochemistry and hematological parameters did not reveal any treatment-associated variations. In sum, these findings suggest that the oral intake of B. clausii M31 at concentrations up to 5×1011CFU/mL for 28days poses no discernible risks.