4-Hydroxymandelic acid (HMA) is widely applied in pharmaceuticals, food and cosmetics. In this study, we aimed to develop an allosteric transcription factors (aTFs) based biosensor for HMA. PobR, an aTF for HMA analog 4-hydroxybenzoic acid, was used to alter its selectivity and create novel aTFs responsive to HMA by directed evolution. We established a PobR mutant library with a capacity of 550,000 mutants using error-prone PCR and Megawhop PCR. Through our screening, two mutants were obtained with responsiveness to HMA. Analysis of each missense mutation indicating residues 122-126 were involved in its PobR ligand speci city. These results showed the effectiveness of directed evolution in switching the ligand speci city of a biosensor and improving HMA production.

An accurate and continuous measurement of heat flux is needed in many long-term operation facilities in order to monitor and improve the life of its machinery. A thin film heat flux sensor is usually fabricated via sputtering, according to different spatial arrangements of thermocouple junctions. A novel thin film heat flux sensor was designed, fabricated, and calibrated, but the connection between the thin film and the leads could not be fixed quickly and steadily. For this purpose, in this paper a method to seamlessly integrate the leads and the thin film has been proposed to improve the sensor output signal. The sensor is capable of simultaneously measuring surface heat flux and temperature magnitude, to address the current situation of the single design of heat flux sensors. The novel thin film heat flux sensor is structured as follows: Thirty pairs of NiCr-NiSi thermocouple junctions are deposited in an annular pattern on a well-designed ceramic substrate. Over the annular thermopile, a 2000 nm-thick thermal insulator layer is deposited to create a temperature gradient across the layers. In addition, in this study a new calibration method was used to evaluate the static and dynamic properties of this novel thin film heat flux sensor. The analysis and experimental results show that the heat flux calculated from the sensor output was in good agreement with the value obtained from the pre-calibrated standard sensor. The sensitivity and response time of the novel sensor were measured at 0.06 mV/(kW/m2) and 475 ms, respectively. The heat flux measurements made with the sensor presented good repeatability. The heat-transfer coefficient of the Al2O3 thin film was 4.477 w/(m∙k) for the novel thin film heat flux sensor described in this paper.

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor in the gastrointestinal tracts and a model for the targeted therapy of solid tumors because of the oncogenic driver mutations in KIT and PDGDRA genes, which could be effectively inhibited by the very first targeted agent, imatinib mesylate. Most of the GIST patients could benefit a lot from the targeted treatment of this receptor tyrosine kinase inhibitor. However, more than 50% of the patients developed resistance within 2 years after imatinib administration, limiting the long-term effect of imatinib. Noncoding RNAs (ncRNAs), the non-protein coding transcripts of human, were demonstrated to play pivotal roles in the resistance of various chemotherapy drugs. In this review, we summarized the mechanisms of how ncRNAs functioning on the drug resistance in GIST. During the drug resistance of GIST, there were five regulating mechanisms where the functions of ncRNAs concentrated: oxidative phosphorylation, autophagy, apoptosis, drug target changes, and some signaling pathways. Also, these effects of ncRNAs in drug resistance were divided into two aspects. How ncRNAs regulate drug resistance in GIST was further summarized according to ncRNA types, different drugs and categories of resistance. Moreover, clinical applications of these ncRNAs in GIST chemotherapies concentrated on the prognostic biomarkers and novel therapeutic targets.

This protocol is used to prepare electrocompetent cells with high transformation efficiency.

This protocol concludes two types of the electrophoresis used to detect target DNA or protein.