Van Hiep Pham

Three-dimensional (3D) bioprinting has rapidly evolved into a controlling platform for the fabrication of patient-specific biomedical implants, with growing importance in advanced drug delivery systems. Beyond structural tissue engineering, bioprinted constructs now function as programmable therapeutic depots capable of localized, sustained, and stimuli-responsive drug release. This review focuses on recent biomaterial design strategies that enable precise control over drug encapsulation, retention, and release kinetics within 3D bioprinted architectures. The physicochemical and mechanical properties of bioinks, including crosslinking density, porosity, degradation behavior, viscoelasticity, and swelling characteristics, directly influence drug loading efficiency and release dynamics under physiological conditions. The rational tuning of these parameters allows the development of constructs that provide spatially controlled and temporally regulated therapeutic delivery. Recent advances in predictive modeling, such as finite element modeling (FEM), data-driven machine learning approaches, and ML, have significantly improved the ability to correlate material composition, printing parameters, and structural geometry with drug diffusion and degradation-mediated release mechanisms. These tools facilitate the optimization of printing variables including extrusion pressure, nozzle diameter, and layer resolution to ensure structural fidelity while maintaining therapeutic functionality. Emerging strategies incorporating multi-material printing, gradient architectures, and stimuli-responsive biomaterials have expanded the potential of 3D bioprinting for combination therapies and personalized medicine. This review discusses key challenges in translating bioprinted drug delivery systems into clinical applications, including the standardization of drug release characterization methods, and long-term stability assessment.

Hàn điểm là phương pháp phổ biến gia công kim loại tấm trong ngành công nghiệp ô tô và hàng không vũ trụ. Trong các ngành công nghiệp này, đánh giá chất lượng mối hàn điểm là một bước không thể thiếu để đáp ứng các yêu cầu về an toàn. Chất lượng mối hàn điểm phụ thuộc vào vật liệu hàn và các thông số hàn như dòng điện hàn, thời gian hàn, và lực tác dụng lên điện cực. Nội dung bài báo trình bày quá trình mô phỏng mối hàn điểm sử dụng phương pháp phần tử hữu hạn (FEM). Quá trình mô phỏng được thực hiện trên phần mềm ANSYS để đánh giá chất lượng của mối hàn. Sự hình thành của đường kính mối hàn được thể hiện dựa trên sự phân bố nhiệt độ thu được từ kết quả mô phỏng. Quá trình mô phỏng hàn điểm của thép tấm 590 DP được thực hiện để xác định đường kính mối hàn, sau đó so sánh với kết quả thực tế để kiểm chứng kết quả mô phỏng. Kết quả chỉ ra rằng giá trị sai lệch lớn nhất là 1.25%, từ đó chứng minh được khả năng của ANSYS trong thực hiện mô phỏng quá trình hàn điểm. Bên cạnh đó, thông số hàn phù hợp được đề xuất dựa theo tiêu chuẩn an toàn của Hiệp hội Hàn Hoa Kỳ (AWS). Các kết quả trên chứng minh khả năng của FEM trong việc dự đoán các thông số hàn phù hợp cho từng loại vật liệu cụ thể.

Integrated photoacoustic and ultrasound (PAUS) imaging is a promising technology for both preclinical and clinical applications, as it exploits both advantages of photoacoustic (PA) and ultrasound (US) imaging in high resolutions and acoustic penetration depth, respectively. Using a shared US transducer, data acquisition (DAQ), and signal processing framework, the PAUS system provides simultaneous functional and anatomical information. To date, numerous studies have been reported to demonstrate the capabilities and proposed innovative approaches for the development of the PAUS probes and systems. Key performance parameters, including probe resolution, extending the region of interest (ROI), and increasing the scanning speed, play critical roles in improving image quality, expanding the scanning area, and reducing the scanning time, respectively. This review aims to summarize recent advances in PAUS probes and systems designed for rapid image acquisition. The principles and signal processing are introduced as the fundamentals for designing the PAUS probes and systems. The summaries of the PAUS probe and system design are presented and compared systematically. Furthermore, new approaches in the development of PAUS probes and systems are proposed to enhance their proficiencies in preclinical and clinical applications.

Nội dung bài báo trình bày phương pháp đơn giản trong việc cân bằng cơ cấu tay quay - con trượt là một dạng biến thể của cơ cấu bốn khâu bản lề, ứng dụng trong thiết kế cơ cấu piston - xy lanh. Do ảnh hưởng của lực rung động tác dụng lên khung cơ cấu, cơ cấu tay quay - con trượt bị rung ảnh hưởng đến khả năng hoạt động của máy. Để cân bằng cơ cấu, các lực rung động gây mất cân bằng được khử bởi đối trọng. Đối trọng được thiết kế cố định ở phía đối diện trên tay quay nhằm cân bằng các lực rung động trong quá trình hoạt động. Công thức của lực rung động được thiết lập để xác định được hình dạng và kích thước phù hợp của đối trọng. Cơ cấu piston - xy lanh với đối trọng được thiết kế dựa trên kết quả mô phỏng đã chứng minh cho quy trình tính toán. Dựa trên kết quả tính toán và mô phỏng để xây dựng sơ đồ thiết kế đối trọng phù hợp với từng ứng dụng của cơ cấu tay quay - con trượt trong thiết kế máy.

This study presents a simple method for balancing a slider-crank mechanism which is applied to a new system. A counterweight is designed and located on the crank link to solve the vibration of slider-crank mechanism. The calculation of counterweight design is proposed to balance the single and double slider-crank mechanisms which are exploited to develop the fast scanning module of scanning acoustic microscopy (SAM) system. Based on the ultrasound characteristics, SAM system can provide the internal image with high resolution up to several tens of micrometers. Following that, the counterweight is optimized to minimize the shaking force acting on the ground frame, resulting in vibration reduction of the SAM system. The equations of shaking force are defined, which are simulated to find out the shape and size of suitable counterweight. Based on the simulation results, counterweights were designed and fabricated, which were used for single and double slider-crank mechanisms of two SAM systems. By interpreting the scanning images provided by SAM systems, the dimensions of specimen are measured at minimum and maximum values that are used to validate the counterweight calculation. Finally, the design process flowchart of counterweight is proposed for balancing slider-crank mechanism, which can be used to extend the mechanism application in many fields.

A scanning acoustic microscopy (SAM) system is a common non-destructive instrument which is used to evaluate the material quality in scientific and industrial applications. Technically, the tested sample is immersed in water during the scanning process. Therefore, a robot arm is incorporated into the SAM system to transfer the sample for in-line inspection, which makes the system complex and increases time consumption. The main aim of this study is to develop a novel water probe for the SAM system, that is, a waterstream. During the scanning process, water was supplied using a waterstream instead of immersing the sample in the water, which leads to a simple design of an automotive SAM system and a reduction in time consumption. In addition, using a waterstream in the SAM system can avoid contamination of the sample due to immersion in water for long-time scanning. Waterstream was designed based on the measured focal length calculation of the transducer and simulated to investigate the internal flow characteristics. To validate the simulation results, the waterstream was prototyped and applied to the TSAM-400 and W-FSAM traditional and fast SAM systems to successfully image some samples such as carbon fiber-reinforced polymers, a printed circuit board, and a 6-inch wafer. These results demonstrate the design method of the water probe applied to the SAM system.

Scanning acoustic microscopy (SAM) system (TSAM-400) was designed and developed for evaluating the quality of resistance spot welding (RSW) joints of 1.5 mm-thick SUS 316 stainless steel sheets under different welding parameters. Indentation and nugget information (diameter and shape) were used for evaluating the RSW quality. SAM A-scan signals were used to calculate the indentation. The nugget diameter was determined in the C-scan image. Internal information (nugget shape, splashes, and defects) was visualized in the B- and C-scan images. In addition, the spot weld area was treated to examine the surface topography effect. The nugget diameters of treated and untreated areas were measured and compared to conclude that the surface topography effect can be neglected in the quality evaluation by SAM system. By implementing TSAM-400, some specimens were successfully tested with a scanning area of 55 × 15 mm², and a scanning time of 33.5 s corresponding to a B-scan frame rate of 4.5 Hz, and a resolution of 0.1 × 0.1 mm². Finally, the good input parameters for welding two 1.5 mm-thick SUS 316 were determined by analyzing the results from TSAM-400.