A brief review on application of design of experiment for the analysis of pharmaceuticals using HPLC

The quality pioneer Dr. Joseph M. Juran first proposed the idea of quality by design. According to him, pharmaceutical quality by design is an organised approach to product development that starts with predetermined goals and places an emphasis on product, process understanding, control based on reliable science and quality risk management. The quality of a product or process can typically be affected by a number of input elements. Design of experiments has been employed widely recently to understand the impacts of multidimensional and interactions of input parameters on the output responses of analytical procedures and pharmaceutical goods. Depending on the design of experiments objectives, screening, characterization, or optimization of the process and formulation, a variety of designs, such as factorial or mixture, can be used. The most popular designs used in the stage of screening or factor selection are the 2-Level Factorial and Plackett-Burman designs, both of which have two levels for each factor (k), both economical and effective, and in optimization widely used designs in this step are full factorial at three levels, central composite, Box-Behnken design. The analysis of variance, regression significance, and lack of fit of the regression model were some of the key topics covered in the discussion of the main components of multiple regression model adjustment. Design of experiments is thus the primary element of the formulation and analytical quality by design. The details about design of experiments used for the analysis of pharmaceutical formulation using HPLC.

Prediction and multi-objective optimization of workability and compressive strength of recycled self-consolidating mortar using Taguchi design method

Concrete is the most consumed material in the construction industry. Using recycled aggregates (RA) and silica fume (SF) in concrete and mortar could preserve natural aggregates (NA) and reduce CO₂ emissions and construction and demolition waste (C&DW) generation. Optimizing the mixture design based on both fresh and hardened properties of recycled self-consolidating mortar (RSCM) has not been performed. In this study, multi-objective optimization of mechanical properties and workability of RSCM containing SF was performed via Taguchi Design Method (TDM) with four main variables including cement content, W/C ratio, SF content and superplasticizer content at three different levels. SF was used to decrease the environmental pollution caused by cement production as well as compensating the negative effect of RA on the mechanical properties of RSCM. The results revealed that TDM could appropriately predict the workability and compressive strength of RSCM. Also, mixture design containing W/C = 0.39, SF = 6%, cement = 750 kg/m³ and SP = 0.33% was found as the optimum mixture having the highest compressive strength and acceptable workability as well as low cost and environmental concerns.

Optimization design of two-stage amplification micro-drive system without additional motion based on particle swarm optimization algorithm

With the increasing requirements of precision mechanical systems in electronic packaging, ultra-precision machining, biomedicine and other high-tech fields, it is necessary to study a precision two-stage amplification micro-drive system that can safely provide high precision and a large amplification ratio. In view of the disadvantages of the current two-stage amplification and micro-drive system, such as poor security, low motion accuracy and limited amplification ratio, an optimization design of a precise symmetrical two-stage amplification micro-drive system was completed in this study, and its related performance was studied. Based on the guiding principle of the flexure hinge, a two-stage amplification micro-drive mechanism with no parasitic motion or non-motion direction force was designed. In addition, the structure optimization design of the mechanism was completed using the particle swarm optimization algorithm, which increased the amplification ratio of the mechanism from 5 to 18 times. A precise symmetrical two-stage amplification system was designed using a piezoelectric ceramic actuator and two-stage amplification micro-drive mechanism as the micro-driver and actuator, respectively. The driving, strength, and motion performances of the system were subsequently studied. The results showed that the driving linearity of the system was high, the strength satisfied the design requirements, the motion amplification ratio was high and the motion accuracy was high (relative error was 5.31%). The research in this study can promote the optimization of micro-drive systems.

Rolling bearing fault diagnosis based on SSA optimized self-adaptive DBN

Due to the structure of rolling bearings and the complexity of the operating environment, collected vibration signals tend to show strong non-stationary and time-varying characteristics. Extracting useful fault feature information from actual bearing vibration signals and identifying bearing faults is challenging. In this paper, an innovative optimized adaptive deep belief network (SADBN) is proposed to address the problem of rolling bearing fault identification. The DBN is pre-trained by the minimum batch stochastic gradient descent. Then, a back propagation neural network and conjugate gradient descent are used to supervise and fine-tune the entire DBN model, which effectively improve the classification accuracy of the DBN. The salp swarm algorithm, an intelligent optimization method, is used to optimize the DBN. Then, the experience of deep learning network structure is summarized. Finally, a series of simulations based on the experimental data verify the effectiveness of the proposed method.

Wing shape optimization design inspired by beetle hindwings in wind tunnel experiments

Flighted beetles have deployable hindwings, which enable them to directly reduce their body size, and thus are excellent bioinspired prototypes for microair vehicles (MAVs). The wing shape of MAVs has an important influence on their aerodynamics. In this paper, wing shapes, inspired from three beetle species' hindwings and designed in terms of the wing camber angle, geometry (including wing length, aspect ratio (AR), and taper ratio (TR)) and wing area, were selected and varied to optimize lift together with the efficiency of wing. All the wings were fabricated by a Tyvek membrane and tested in a wind tunnel. The camber angle and AR were found to have a critical role in force production. The best performance was obtained by a wing with a camber angle of 10°, wing length of 125 mm, AR of 7.06, TR of 0.40 and wing area of 4115 mm².

Biomechanical design and analysis of auxetic pedicle screw to resist loosening

BACKGROUND

Pedicle screws are widely used in fusion surgery, while screw loosening often occurrs. An auxetic structures based pedicle screw was proposed to improve the bone-screw fixation by radial expansion of the screw body under tensile force to resist pulling out. It was optimized to obtain excellent anti-pullout ability for a particular bone based on the biomechanical interaction between screw and surrounding bone.

METHODS

The screw was designed based on re-entrant unit cells. The mechanical properties of it were adjusted by the wall thickness (t) and re-entrant angle (θ) of the unit cell, and characterized using finite element (FE) method. The designed screws were manufactured using 3D-printing, and Ti6Al4V as the materials. Subsequently, the pullout FE models were established, and verified by pulling the fabricated screws out of Sawbone blocks. The pulling out processes of screws from bone were simulated to explore the optimizing design of the screw.

RESULTS

The mechanical properties of the screw could be adjusted in a wide range. The biomechanical interaction between the screw and bone can affect the anti-pullout performance of the screw. With an identical elastic modulus (E), better auxiticity of the screw, resulted in a better anti-pullout performance; while an appropriate E is the necessary condition for its excellent anti-pullout performance for a particular bone.

CONCLUSION

Appropriate mechanical properties are necessary for the auxetic pedicle screw with excellent screw-bone fixation performance for a particular bone, which can be obtained by rationally designing the wall thickness and re-entrant angle of the unit cells.

Nitrogen and sulfur co-doped biochar derived from peanut shell with enhanced adsorption capacity for diethyl phthalate

Doping of nitrogen and sulfur on biochar (NS-B) was investigated by a novel and improved method for diethyl phthalate (DEP) removal. The preparation parameters including pyrolysis temperature and size of peanut shell biochar as well as thiourea/biochar mass ratio were selected as independent variables at three levels by applying the Box-Behnken design. The ANOVA results indicated that thiourea/biochar mass ratio exhibited the most significant effect. The comprehensive effects of the three factors on DEP removal efficiency were further elaborated, combining with the characterization results of the obtained NS-B materials. The formation of the pyridinic N and oxidized S groups examined by XPS was responsible for enhancing the DEP removal efficiency. The adsorption kinetic model fitting illustrated that large micropores and numerous adsorption sites improved the adsorption capacity of NS-B. According to the adsorption isotherm model fitting, NS-B (temperature 375 °C, size 300 mesh and thiourea/biochar mass ratio 0.1) possessed much higher maximum adsorption capacity for DEP (14.34 mg g^-1) than biochar (6.57 mg g^-1). NS-B exhibited excellent reusability towards DEP removal after five times recycling. Moreover, NS-B also had the potential in peroxydisulfate activation. These findings provide new insights into the environmental implications of NS-B.

Optimal design of selective catalyst reduction denitrification system using numerical simulation

The performance of selective catalyst reduction systems highly depends on the degree of mixing between NH₃ and NO_x and the flow uniformity of velocity and concentration, which are sensitive to several parameters such as the installment of gate leafs, a hybrid grid, a straightener, and the ammonia injection method. In this work, computational fluid dynamics was applied to investigate these parameters in heat recovery steam generators. Performance of gate leafs and a new type of hybrid grid was considered. Analyses showed that gate leafs significantly improved the uniformity of velocity distribution and that the new type of hybrid grid improved the uniformity of concentration distribution. The velocity relative standard deviation decreased from 19.6% to 5.4%, and the concentration relative standard deviation decreased from 70% to 12.7%. Experiments also qualitatively confirmed the reliability of simulation results. Moreover, the hybrid grid was optimized with different structures. Results indicated that a 30° crossed angle could obtain a better mixing between NH₃ and NO_x with a slight decrease in pressure. In addition, an optimal injection method of the ammonia injection grid was designed, and it was helpful in conducting the field operation. The relationship between the thickness of the straightener and the incident angle at the entrance of catalyst layer was discussed.

A review of the design methods of complex topology structures for 3D printing

As a matter of fact, most natural structures are complex topology structures with intricate holes or irregular surface morphology. These structures can be used as lightweight infill, porous scaffold, energy absorber or micro-reactor. With the rapid advancement of 3D printing, the complex topology structures can now be efficiently and accurately fabricated by stacking layered materials. The novel manufacturing technology and application background put forward new demands and challenges to the current design methodologies of complex topology structures. In this paper, a brief review on the development of recent complex topology structure design methods was provided; meanwhile, the limitations of existing methods and future work are also discussed in the end.

Finite-element design and optimization of a three-dimensional tetrahedral porous titanium scaffold for the reconstruction of mandibular defects

Reconstruction of segmental defects in the mandible remains a challenge for maxillofacial surgery. The use of porous scaffolds is a potential method for repairing these defects. Now, additive manufacturing techniques provide a solution for the fabrication of porous scaffolds with specific geometrical shapes and complex structures. The goal of this study was to design and optimize a three-dimensional tetrahedral titanium scaffold for the reconstruction of mandibular defects. With a fixed strut diameter of 0.45mm and a mean cell size of 2.2mm, a tetrahedral structural porous scaffold was designed for a simulated anatomical defect derived from computed tomography (CT) data of a human mandible. An optimization method based on the concept of uniform stress was performed on the initial scaffold to realize a minimal-weight design. Geometric and mechanical comparisons between the initial and optimized scaffold show that the optimized scaffold exhibits a larger porosity, 81.90%, as well as a more homogeneous stress distribution. These results demonstrate that tetrahedral structural titanium scaffolds are feasible structures for repairing mandibular defects, and that the proposed optimization scheme has the ability to produce superior scaffolds for mandibular reconstruction with better stability, higher porosity, and less weight.

Pseudomonas sp. ZXY-1, a newly isolated and highly efficient atrazine-degrading bacterium, and optimization of biodegradation using response surface methodology

Atrazine, a widely used herbicide, is increasing the agricultural production effectively, while also causing great environmental concern. Efficient atrazine-degrading bacterium is necessary to removal atrazine rapidly to keep a safe environment. In the present study, a new atrazine-degrading strain ZXY-1, identified as Pseudomonas, was isolated. This new isolated strain has a strong ability to biodegrade atrazine with a high efficiency of 9.09mg/L/hr. Temperature, pH, inoculum size and initial atrazine concentration were examined to further optimize the degradation of atrazine, and the synthetic effect of these factors were investigated by the response surface methodology. With a high quadratic polynomial mathematical model (R²=0.9821) being obtained, the highest biodegradation efficiency of 19.03mg/L/hr was reached compared to previous reports under the optimal conditions (30.71°C, pH7.14, 4.23% (V/V) inoculum size and 157.1mg/L initial atrazine concentration). Overall, this study provided an efficient bacterium and approach that could be potentially useful for the bioremediation of wastewater containing atrazine.

Development of an ultrasonic linear motor with ultra-positioning capability and four driving feet

This paper presents a novel linear piezoelectric motor which is suitable for rapid ultra-precision positioning. The finite element analysis (FEA) was applied for optimal design and further analysis, then experiments were conducted to investigate its performance. By changing the input signal, the proposed motor was found capable of working in the fast driving mode as well as in the precision positioning mode. When working in the fast driving mode, the motor acts as an ultrasonic motor with maximum no-load speed up to 181.2mm/s and maximum thrust of 1.7N at 200Vp-p. Also, when working in precision positioning mode, the motor can be regarded as a flexible hinge piezoelectric actuator with arbitrary motion in the range of 8μm. The measurable minimum output displacement was found to be 0.08μm, but theoretically, can be even smaller. More importantly, the motor can be quickly and accurately positioned in a large stroke.