Oral administration microrobots for drug delivery.

Oral administration is the most simple, noninvasive, convenient treatment. With the increasing demands on the targeted drug delivery, the traditional oral treatment now is facing some challenges: 1) biologics how to implement the oral treatment and ensure the bioavailability is not lower than the subcutaneous injections; 2) How to achieve targeted therapy of some drugs in the gastrointestinal tract? Based on these two issues, drug delivery microrobots have shown great application prospect in oral drug delivery due to their characteristics of flexible locomotion or driven ability. Therefore, this paper summarizes various drug delivery microrobots developed in recent years and divides them into four categories according to different driving modes: magnetic-controlled drug delivery microrobots, anchored drug delivery microrobots, self-propelled drug delivery microrobots and biohybrid drug delivery microrobots. As oral drug delivery microrobots involve disciplines such as materials science, mechanical engineering, medicine, and control systems, this paper begins by introducing the gastrointestinal barriers that oral drug delivery must overcome. Subsequently, it provides an overview of typical materials involved in the design process of oral drug delivery microrobots. To enhance readers' understanding of the working principles and design process of oral drug delivery microrobots, we present a guideline for designing such microrobots. Furthermore, the current development status of various types of oral drug delivery microrobots is reviewed, summarizing their respective advantages and limitations. Finally, considering the significant concerns regarding safety and clinical translation, we discuss the challenges and prospections of clinical translation for various oral drug delivery microrobots presented in this paper, providing corresponding suggestions for addressing some existing challenges.

Improved control method of the paralleled three-phase two-level inverters for common-mode voltage and circulating current suppression.

The paralleled configuration of three-phase two-level (3P2L) inverters has been put forward to increase the output power rating, operating efficiency, and system reliability. Nevertheless, this architecture brings about the serious circulating current problem, which distorts the quality of output currents, results in additional power losses, and reduces the system efficiency. Another problem is the common-mode voltage (CMV), which causes electromagnetic interference and threatens the safe operation of the system. There exists interconnection between these two issues in the paralleled 3P2L inverters. To suppress the CMV and circulating current simultaneously, an improved control method is presented. At first, the discrete model of paralleled 3P2L inverters is established, based on which the improved control method is designed to restrain the circulating current, while the parameter tuning is avoided. In addition, the zero-sequence component injection associated with the optimized configuration of carrier phase is conducted, and the CMV magnitude of each inverter is limited within one-sixth of dc-side voltage. When comparing with the traditional space vector modulation (SVM) approach, the CMV magnitude is restrained by two-thirds by the presented method. The hardware-based evaluation results have been provided to validate the presented approach.

The Impact of Cooperative Behavior between Social Organizations during the COVID-19 Pandemic Outbreak in Shanghai: A Simulation Approach.

In 2022, a new outbreak of the COVID-19 pandemic created considerable challenges for the Shanghai public health system. However, conventional prevention and control strategies, which only rely on formal organizations, inefficiently decrease the number of infections. Thus, a multi-organization management mode is needed for pandemic prevention. In this paper, we applied a stochastic actor-oriented model (SAOM) to analyze how these social organizations cooperate with others and further identify the mechanism that drives them to create a reliable and sustainable cooperative relationship network from the perspective of social network analysis. The model allowed us to assess the effects of the actor's attributes, the network structure, and dynamic cooperative behavior in RSiena with longitudinal data collected from 220 participants in 19 social organizations. The results indicated that the number of cooperative relationships increased during the pandemic, from 44 to 162, which means the network between social organizations became more reliable. Furthermore, all the hypotheses set in four sub-models were significant (t-ratio < 0.1, overall max t-ratio < 0.25, and e/s > 2). Additionally, the estimated values showed that four factors played a positive role in forming the cooperative relationship network, i.e., all except the "same age group effect (−1.02)". The results also indicated that the social organizations tend to build relationships with more active actors in the community in every time period. This paper is of great significance regarding the innovation of public health system management and the improvement of Chinese grassroots governance.

Improved control scheme for simultaneous reduction of common-mode voltage and current harmonic distortion of the Vienna-type rectifier with balanced and unbalanced neutral-point voltages.

As a non-generative-boost rectifier, the Vienna-type rectifier has been proposed and applied in several applications, such as wind power generation systems, battery charging system, etc. This paper further proposes an improved control scheme for reducing common-mode voltage (CMV) and input current harmonic distortions under balanced and unbalanced neutral-point (NP) voltages. At first, the operating fundamentals of the Vienna-type rectifier are presented. The zero-sequence voltage and its corresponding ranges are carefully derived to control the dc-link capacitor voltages separately. Considering the specific constraint of this rectifier, the zero-sequence voltage is further revised to reduce the current harmonic distortions around the zero-crossing points. Doing so, the simultaneous reduction of CMV and input current harmonic distortions can be realized, which is applicable to balanced and unbalanced NP voltages. The comparisons of the proposed scheme, the conventional zero-sequence voltage injection scheme, and the CMV reduction method under balanced NP voltage condition are conducted, which demonstrate the salient advantages of the presented scheme.