Research on bearing fault diagnosis based on improved genetic algorithm and BP neural network.

Health monitoring and fault diagnosis of rolling bearings are crucial for the continuous and effective operation of mechanical equipment. In order to improve the accuracy of BP neural network in fault diagnosis of rolling bearings, a feature model is established from the vibration signals of rolling bearings, and an improved genetic algorithm is used to optimize the initial weights, biases, and hyperparameters of the BP neural network. This overcomes the shortcomings of BP neural network, such as being prone to local minima, slow convergence speed, and sample dependence.

Study on aluminum nitride/addition-cure liquid silicone rubber composite for high-voltage power encapsulation.

In view of the development direction of high power and miniaturization of high-voltage power supply, higher requirements are put forward for the breakdown strength, thermal conductivity of packaging materials for its high voltage output module. An electric-insulated heat-conducted material with aluminium nitride as heat conducting filler and addition-cure liquid silicone rubber (ALSR) as matrix for high voltage power encapsulation has been studied. Initially, the thermal conductivity and breakdown strength of composites were explored at different filler fractions.

Research on the thermal conductivity and dielectric properties of AlN and BN co-filled addition-cure liquid silicone rubber composites.

The present work aims at studying the thermal and dielectric properties of addition-cure liquid silicone rubber (ALSR) matrix composites using boron nitride (BN) and aluminum nitride (AlN) as a hybrid thermal conductive filler. Composite samples with different filler contents were fabricated, and the density, thermal conductivity, thermal stability, dielectric properties, and volume resistivity of the samples were measured. According to the experimental results, the density, thermal conductivity, dielectric constant and dielectric loss tangent values all increased with the increasing addition of filler.

Synthesis and biological assays of 9-(acylamino) homocamptothecins as DNA topoisomerase I inhibitors.

In an effort to improve the stability of homocamptothecin and reduce the toxicity, novel homocamptothecin analogs with acylamino groups at C(9) were designed and synthesized. The cytotoxic activities of all the synthetic compounds against three cancer cell lines were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, and irinotecan was used as reference compound. Compound 7c with a piperidinylacetamido group and 10a with phenylacetamido group at C(9) showed potent activities both in vitro and in vivo.

A new strategy to improve the metabolic stability of lactone: discovery of (20S,21S)-21-fluorocamptothecins as novel, hydrolytically stable topoisomerase I inhibitors.

Lactone is a common structural motif in biologically active natural products. However, the metabolic instability of lactone significantly reduces their in vivo potency. In the present investigation, a new strategy to improve the metabolic stability of lactone was provided by the design of α-fluoro ether as a novel bioisostere of lactone.

Synthesis and preliminary bioevaluation of novel E-ring modified acetal analog of camptothecin as cytotoxic agents.

In an effort to improve the metabolic stability of the E-ring and decrease the toxicity of camptothecin (CPT), a novel cytotoxic acetal analog with 21-alkoxy groups was designed and synthesized. The preliminary results revealed that this class of compounds showed superior antiproliferative activity in vitro and moderate in vivo activity, while their topoisomerase I (Topo I) inhibitory activity was weakened significantly. The implications of these results within the current understanding of the structure-activity relationship of camptothecin are analyzed in detail.

Discovery, synthesis, and biological evaluation of orally active pyrrolidone derivatives as novel inhibitors of p53-MDM2 protein-protein interaction.

The p53-MDM2 interaction has been proved to be a valuable target to develop effective antitumor agents. Novel p53-MDM2 inhibitors bearing pyrrolidone scaffolds were successfully identified by structure-based design. The nanomolar inhibitor 5 possessed good p53-MDM2 inhibitory activity (K(i) = 780 nM) due to its hydrophobic and hydrogen bonding interactions with MDM2.

Structure-activity relationship and antitumor activity of thio-benzodiazepines as p53-MDM2 protein-protein interaction inhibitors.

In order to discuss the structure-activity relationship (SAR) of the thio-benzodiazepine compounds which showed excellent activity against p53-MDM2 protein-protein interaction, we designed and synthesized twenty compounds with electrophilic and nucleophilic groups on the benzene ring. Among them, compounds 8i (K(i) = 91 nM) and 8n (K(i) = 89 nM) showed better binding activity than that of the reference drug Nutlin-3a (K(i) = 121 nM). In addition, in vitro antitumor activity against Saos-2, U-2 OS, A549 and NCI-H1299 cell-lines were assayed by the MTT method.

[Determination of sodium by near infrared spectroscopy].

The research on near infrared spectroscopy of sodium in biological and medicine is significant. Sodion is the main component of electrolytes in human blood and electrolytes help maintain the body's acid-base balance. In the present paper the concentration of sodium was determined with the use of NIR spectra.

Synthesis and biological evaluation of 7-alkenyl homocamptothecins as potent topoisomerase I inhibitors.

Homocamptothecin (hCPT) is a camptothecin (CPT) derivative with a seven-membered β-hydroxylactone E ring, which shows higher lactone stability and improves topoisomerase I (Topo I) inhibition activity. In an attempt to improve the antitumor activity of homocamptothecins, a series of 7-alkenyl-homocamptothecin derivatives was designed and synthesized based on a semisynthetic route starting from CPT. Most of the synthesized compounds exhibit higher cytotoxic activities on the A-549 tumor cell line than topotecan (TPT).

Design, synthesis and structure-activity relationships of new triazole derivatives containing N-substituted phenoxypropylamino side chains.

The incidence of invasive fungal infections and resistance to antifungal agents is increasing dramatically. It is highly desirable to develop novel azoles with improved biological profiles. The structure-activity relationship (SAR) of the N-substitutions was investigated in this study.

[On-line and in-situ spectral analysis of multicomponent gas mixture with same molecular group].

Aimed at the problem that Fourier transform infrared (FTIR) spectral analysis can't be used solely to analyze complex gas mxiture, in which there are many gas compositions, some compositions have same molecular group, and the concentrations of some compositions range greatly, in the present paper, a new spectral analysis method is proposed. For this method, the effects of gas temperature and gas pressure on the analysis result are taken into account, and feature variable extraction, recognition and correction of spectral disorder, robust modeling and multi-layer modeling with neural network (NN) are used to build gas mixture analysis models. At the end of this paper, on-line analysis of five alkane gases is taken as example to test the performance of the analysis method.

Synthesis and biological evaluation of thio-benzodiazepines as novel small molecule inhibitors of the p53-MDM2 protein-protein interaction.

A series of thio-benzodiazepine p53-MDM2 inhibitors were designed and synthesized based on the principle of bioisosterism. Most of the thio-benzodiazepines had nanomolar to micromolar affinity toward MDM2. Particularly, compounds 8a (K(i) = 0.

Synthesis and biological evaluation of novel homocamptothecins conjugating with dihydropyrimidine derivatives as potent topoisomerase I inhibitors.

Homocamptothecin (hCPT) is a camptothecin (CPT) homologue with the insertion of a methylene (CH₂) spacer between the alcohol moiety and carbonyl group of the classical six-membered α-hydroxylactone ring. This modification provides higher lactone stability and did not impair its activity against topoisomerase I (Topo I), but rather appears to improve it compared to CPT. In an attempt to improve the antitumor activity of homocamptothecins, a series of novel hCPT derivatives conjugating with dihydropyrimidine (DHPM) derivatives was designed and synthesized based on a synthetic route which couples 7-formylhomocamptothecin with different dihydropyrimidine derivates.

Synthesis of novel benzoxanthone analogues as non-Camptothecin topoisomerase I inhibitors.

Structure modification of the side chain of the lead compound benzoxanthone provided a series of benzoxanthone analogues and 12 of them were first reported. The results showed that most of these compounds had moderate cytotoxicity against tumour cells with the 50% inhibition concentration in the micromolar range. Furthermore, benzoxanthone derivatives 5, 6c, 7a and 7e, showed potent topoisomerase I (Topo I) inhibitory effect and the results indicated that some compounds had potential for development as non-Camptothecin (CPT) topoisomerase I inhibitors.

Synthesis of 9-(heteroarylmethylidene)amino derivatives of homocamptothecin with biological activities.

Six 9-(heteroarylmethylidene)amino derivatives, 2a-2f, of homocamptothecin were synthesized for the first time by total synthesis in 22 steps and biologically evaluated as inhibitors of topoisomerase I. Moreover, the antitumor activities of 2a-2f against three human tumor cell lines, i.e.

Synthesis and biological evaluation of novel 7-acyl homocamptothecins as Topoisomerase I inhibitors.

A series of novel 7-acyl derivatives of homocamptothecin (hCPT) were designed and synthesized with the purpose to improve antitumor activity of hCPT, via Minisci free-radical reaction from 10-methoxyhomocamptothecin. All the compounds were evaluated for in vitro cytotoxicity against three cancer cell lines (A549, MDA-MB-435 and HCT116). For MDA-MB-435 cell line, compounds, 6a, 6b, 6k and all of 7-alkylcabonyl homocamptothecin derivatives showed higher in vitro inhibitory activities than topotecan (TPT).

[A method for quantitative analysis system of alkane gaseous mixture with near infrared spectroscopy].

A method for online quantitative analysis system of alkane gaseous mixture with near infrared spectroscopy is described in the present paper. A single plane diffraction grating is used as the principal device in the monochromatic spectrum system. The key parameters of the monochromator were deduced and calculated in detail.

Trifluoromethyl-promoted homocamptothecins: synthesis and biological activity.

The homocamptothecin (hCPT) represents a new class of topoisomerase inhibitor which combines enhanced plasma stability and strong antitumor activity. Fluorine imparts desirable characteristics to drugs by modulating both the pharmacokinetics and pharmacodynamic properties of a drug. Therefore, in an attempt to improve the antitumor activity of homocamptothecins, seven new 7-trifluoromethylated homocamptothecin derivatives were prepared by proline-catalyzed Friedlander annulation.

Synthesis and evaluation of 9-benzylideneamino derivatives of homocamptothecin as potent inhibitors of DNA topoisomerase I.

A series of novel 9-benzylideneamino derivatives of homocamptothecin were synthesized via Friedlaender cyclization from our obtained intermediate 5. All the compounds were evaluated for in vitro cytotoxicity against three cancer cell lines (A549, LOVO and MDA-MB-435). Most of these derivatives possessed potent growth inhibitory effect on all the tested cell lines and four compounds (6d, 6f, 6i, 6k) showed higher inhibitory activities with the IC50 values of 2.