COVID-19 is associated with the risk of cardiovascular disease death: A two-sample Mendelian randomization study.

Objective: This study aimed to estimate the causal effects of Coronavirus disease 2019 susceptibility and hospitalization on cardiovascular disease death using two-sample Mendelian randomization analysis. Methods: We used statistics from a genome-wide association study. A total of 2,568,698 participants were assessed in this study, including 1,299,010 in Coronavirus disease 2019 susceptibility databases, 908,494 in Coronavirus disease 2019 hospitalization database, and 361,194 in a cardiovascular disease death database. We performed two-sample Mendelian randomization analysis using the inverse variance weighted method. As sensitivity analysis techniques, Mendelian randomization-Egger regression, heterogeneity analyses, and Leave-one-out analysis were employed. Reverse Mendelian randomization analysis was used to detect reverse causality. Statistical significance was defined as P < 0.05. Results: Coronavirus disease 2019 susceptibility may be a causal factor for cardiovascular disease death (ß = 2.188 × 10-3, P = 0.002), which involves five common single nucleotide polymorphisms. Similarly, Coronavirus disease 2019 hospitalization may also be a causal factor for cardiovascular disease death (ß = 8.626 × 10-4, P = 0.010), which involves nine common single nucleotide polymorphisms. Furthermore, sensitivity and reverse Mendelian randomization analysis suggested that no heterogeneity, horizontal pleiotropy or reverse causality was found between Coronavirus disease 2019 and cardiovascular disease death. Conclusion: Our bidirectional Mendelian randomization analysis showed a causal relationship between Coronavirus disease 2019 susceptibility and hospitalization associated with an increased risk of cardiovascular disease death.

The Influence of Teacher-Student Interaction on the Effects of Online Learning: Based on a Serial Mediating Model.

During the COVID-19 pandemic, online education has become an important approach to learning in the information era and an important research topic in the field of educational technology as well as that of education in general. Teacher-student interaction in online education is an important factor affecting students' learning performance. This study employed a questionnaire survey to explore the influence of teacher-student interaction on learning effects in online education as well as the mediating role of psychological atmosphere and learning engagement. The study involved 398 college students studying at Chinese universities as the research object. Participants filled out a self-report questionnaire. The study found that (1) the level of teacher-student interaction positively affected students' learning effects (r = 0.649, p < 0.01). (2) The psychological atmosphere mediated the positive effect of the level of teacher-student interaction on learning effects with mediating effect value of 0.1248. (3) Learning engagement mediated the positive effect of teacher-student interaction on learning effects with a mediating effect value of 0.1539. (4) The psychological atmosphere and learning engagement play a chain-mediating role in the mechanism of teacher-student interaction affecting students' learning effects; that is, teacher-student interaction promotes students' learning engagement by creating a good psychological atmosphere, which, in turn, influences learning effects. The mediating effect value was 0.0403. The results indicate that teacher-student interaction not only directly affects students' learning effects but also influences students' learning effects through the mediating effect of the psychological atmosphere and learning engagement.

First Identification and Investigation of piRNAs in the Larval Gut of the Asian Honeybee, Apis cerana.

Piwi-interacting RNAs (piRNAs), a class of small non-coding RNAs (ncRNAs), play pivotal roles in maintaining the genomic stability and modulating biological processes such as growth and development via the regulation of gene expression. However, the piRNAs in the Asian honeybee (Apis cerana) are still largely unknown at present. In this current work, on the basis of previously gained high-quality small RNA-seq datasets, piRNAs in the larval gut of Apis cerana cerana, the nominated species of A. cerana, were identified for the first time, followed by an in-depth investigation of the regulatory roles of differentially expressed piRNAs (DEpiRNAs) in the developmental process of the A. c. cerana. Here, a total of 621 piRNAs were identified in A. c. cerana larval guts, among which 499 piRNAs were shared by 4-(Ac4 group), 5-(Ac5 group), and 6-day-old (Ac6 group) larval guts, while the numbers of unique ones equaled 79, 37, and 11, respectively. The piRNAs in each group ranged from 24 nucleotides (nt) to 33 nt in length, and the first base of the piRNAs had a cytosine (C) bias. Additionally, five up-regulated and five down-regulated piRNAs were identified in the Ac4 vs. Ac5 comparison group, nine of which could target 9011 mRNAs; these targets were involved in 41 GO terms and 137 pathways. Comparatively, 22 up-regulated piRNAs were detected in the Ac5 vs. Ac6 comparison group, 21 of which could target 28,969 mRNAs; these targets were engaged in 46 functional terms and 164 pathways. The results suggested an overall alteration of the expression pattern of piRNAs during the developmental process of A. c. cerana larvae. The regulatory network analysis showed that piR-ace-748815 and piR-ace-512574 in the Ac4 vs. Ac5 comparison group as well as piR-ace-716466 and piR-ace-828146 in the Ac5 vs. Ac6 comparison group were linked to the highest number of targets. Further investigation indicated that targets of DEpiRNAs in the abovementioned two comparison groups could be annotated to several growth and development-associated pathways, such as the Jak/STAT, TGF-ß, and Wnt signaling pathways, indicating the involvement of DEpiRNAs in modulating larval gut development via these crucial pathways. Moreover, the expression trends of six randomly selected DEpiRNAs were verified using a combination of stem-loop RT-PCR and RT-qPCR. These results not only provide a novel insight into the development of the A. c. cerana larval gut, but also lay a foundation for uncovering the epigenetic mechanism underlying larval gut development.

A randomized controlled study on color stability of tetracycline teeth restored with ceramic veneer.

OBJECTIVES: This study aimed to evaluate the color stability of tetracycline teeth restored with ceramic veneers of different thicknesses combined with different resin cement systems after aging. METHODS: Twenty patients with tetracycline teeth, including two maxillary central incisors, were selected clinically. The patients were randomly divided into four groups and restored with 0.5 and 0.75 mm ceramic veneers by using a veneer adhesive system, either with light-cured or dual-cured reaction. The color difference (ΔE) values after cementation and 1, 6, 12, and 24 months of use were obtained by quantification of L*, a*, and b* values with a colorimeter. The results were analyzed statistically with two-way ANOVA and Student's t test. RESULTS: The ΔE values of ceramic veneers detected after aging were less than 2.25. The 0.5 mm groups exhibited greater color change than the 0.75 mm-thick veneers (P<0.05). No significant difference was found on the color change of dual- or light-cured resin cements. CONCLUSIONS: Resin cements and veneer thickness influence the color of ceramic veneers after aging. Cementation of veneers with either dual- or light-cured resin cements does not affect the long-term color stability of tetracycline teeth differently.

An optimized band-target entropy minimization for mass spectral reconstruction of severely co-eluting and trace-level components.

Gas chromatography-mass spectrometry (GC-MS) is a versatile analytical method but its data is usually complicated by the presence of severely co-eluting and trace-level components. In this work, we introduce an optimized band-target entropy minimization approach for the analysis of complex mass spectral data. This new approach enables an automated mass spectral analysis which does not require any user-dependent inputs. Moreover, the approach provides improved sensitivity and accuracy for mass spectral reconstruction of severely co-eluting and trace-level components. The accuracy of our approach is compared to the automatic mass spectral deconvolution and identification system (AMDIS) with two controlled mixtures and a sample of Eucalyptus essential oil. Our approach was able to putatively identify 130 compounds in Eucalyptus essential oil, which was 46% in excess of that identified by AMDIS. This new approach is expected to benefit GC-MS analysis of complex mixtures such as biological samples and essential oils, in which the data are often complicated by co-eluting and trace-level components. Graphical abstract ᅟ.

[Effect of dexmedetomidine postconditioning on myocardial ischemia-reperfusion injury and inflammatory response in diabetic rats].

OBJECTIVE: To investigate the effect of dexmedetomidine postconditioning in alleviating myocardial ischemia-reperfusion (IR) injury and inflammation in diabetic mellitus rats. METHODS: Thirty normal male Sprauge Dawley (SD) rats were randomly allocated into 3 groups (n=10), namely the sham-operated group, IR group, and dexmedetomidine postconditioning (DP) group. Similarly, another thirty diabetic SD rats were also randomly allocated into diabetic sham (DM-S) group, diabetic IR (DM-IR) group and diabetic dexmedetomidine postconditioning (DM-DP) group. The mean arterial pressure (MAP), heart rate (HR) and the rate pressure product (RPP) were recorded at baseline, after 30 min of ischemia, and at 30 and 120 min during reperfusion. Myocardial infarct size was analyzed by TTC double staining method, and plasma levels of CTnI, TNF-a, IL-6, IL-10 and IL-1ß were measured at 120 min of reperfusion. RESULTS: Compared with those in the sham-operated group, normal and diabetic rats in IR and DP groups showed significantly lowered MAP, HR, and RPP and increased levels of plasma CTnI, TNF-a, IL-6, IL-10 and IL-1ß levels after 30 min of ischemia and at 30 min and 120 min of reperfusion (P<0.05). Compared with those in the IR group, the normal rats in DP group showed decreased MAP, HR, and RPP at 30 min of ischemia and at 30 min of reperfusion, which increased at 120 min of reperfusion (P<0.05); the infarct size and plasma CTnI, TNF-a, IL-6 and IL-1ß levels were decreased while IL-10 was increased in DP group (P<0.05). Compared with those in DP group, the rats in DM-DP group showed similar MAP, HR and RPP (P>0.05) but significantly increased infarct size and plasma CTnI, TNF-a, IL-6 and IL-1ß levels (P<0.05). CONCLUSION: Dexmedetomidine postconditioning may produce a cardioprotective effect against myocardial IR injury in normal rats by alleviating inflammation, but can not reduce the release of inflammatory mediators in diabetic rats to improve myocardial infarction.

[Effect of high concentration glucose on the expression of ALDH2 in cardiac fibroblasts of rats].

OBJECTIVE: To observe whether acetaldehyde dehydrogenase 2 (ALDH2) is expressed in cardiac fibroblasts and investigate the change of ALDH2 in cardiac fibroblasts when cultured with high concentration of glucose. METHODS: Cultured cardiac fibroblasts were randomly divided into four groups:normal control group (5.5 mmol/L glucose), Alda-1 (the agonist of ALDH2, 20µmol/L) group, high glucose group (30 mmol/L glucose) and high glucose + Alda-1 group. Cardiac fibroblasts were identified by immunofluore-scence technique. Cell prolifera-tion was detected by MTT method after treated with drugs for 48 hours. mRNA and protein expressions of ALDH2 were determined by RT-PCR and Western blot, aimed to ensure whether ALDH2 was expressed in cardiac fibroblasts. The changes of ALDH2 protein expression in cardiac fibroblasts were tested by Western blot. RESULTS: RT-PCR and Western blot results revealed that ALDH2 was expressed in cardiac fibroblasts. Compared with normal control group, cardiac fibroblasts proliferation was increased (P < 0.05), while the protein expression of ALDH2 was reduced (P < 0.05) in high glucose group. When treated with Alda-1, the proliferation of cardiac fibroblasts was decreased (P < 0.01), while the protein expression of ALDH2 was increased (P < 0.05) in high glucose group. CONCLUSIONS: ALDH2 was expressed in cardiac fi-broblasts. Alda-1, the agonist of ALDH2 enhanced the expression of ALDH2 and inhibited the proliferation of cardiac fibroblasts when cultured with high concentration of glucose.

[Role of autophagy in fasudil-induced Rho kinase inhibition for protection against myocardial ischemia-reperfusion injury in rats].

OBJECTIVE: To investigate the changes of autophagy in ischemic myocardium of rats treated with fasudil for inhibiting Rho kinase. METHODS: The hearts isolated from male Sprague-Dawley rats were subjected to 30 min of occlusion of the left anterior descending artery followed by 120 min of reperfusion with or without treatment with fasudil or fasudil+Wort. The left ventricular hemodynamics were continuously recorded, and the coronary effluent was collected during the reperfusion to determine lactate dehydrogenase (LDH) levels. The mRNA expressions of autophagy-related genes Atg5 and Beclin1 and apoptosis-related genes bax and bcl-2 were detected by RT-PCR, and the protein expression of caspase-3 was detected by Western blotting. RESULTS: Compared with I/R group, fasudil significantly improved the left ventricular developed pressure, maximal rise/fall rate of left ventricular pressure and rate pressure product, reduced LDH release during reperfusion, increased Atg5 and Beclin1 mRNA expression and the ratio of Bcl-2/Bax, and lowered caspase 3 protein expression. The autophagy inhibitor Wort significantly attenuated the effect of fasudil in the rat hearts. CONCLUSION: Fasudil treatment for inhibiting Rho kinase promoted autophagy in ex vivo rat heart to protect against myocardial ischima-reperfusion injury possibly by reducing apoptosis of the cardiac myocytes.

Effects of endomorphin-1 postconditioning on myocardial ischemia/reperfusion injury and myocardial cell apoptosis in a rat model.

Endomorphins (EMs) have important roles in the body with regards to analgesia, feeding behavior, gastrointestinal movement and inflammatory reaction. Recent studies have reported that EMs may also participate in chronic hypoxia in the protection of rat myocardial ischemia/reperfusion; however, the mediator and underlying mechanisms remain to be elucidated. The aim of the present study was to investigate the effects of EM­1 postconditioning on myocardial ischemia/reperfusion injury (MIRI) and myocardial cell apoptosis in a rat model, and to assess its likely mechanisms. A total of 48 male Sprague Dawley rats were randomly divided into four groups: Sham group, ischemia/reperfusion group (IR group), ischemic postconditioning group (IPO group) and EM­1 postconditioning group (EM50 group). A MIRI model was established via occlusion of the left anterior descending branch of the coronary artery for 30 min, followed by reperfusion for 120 min in vivo. Hemodynamic indexes were recorded and analyzed. Following reperfusion, plasma lactate dehydrogenase (LDH), creatine kinase­MB (CK­MB), malondialdehyde (MDA), superoxide dismutase (SOD), interleukin­6 (IL­6) and tumor necrosis factor­α (TNF­α) contents or activities were measured, infarct size was determined, and the expression levels of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) mRNA and cleaved caspase­3 protein were assessed. In the IR group, mean arterial pressure (MAP) and heart rate (HR) were decreased compared with in the sham group. In addition, LDH and CK­MB levels were increased; IL­6, TNF­α and MDA content was increased; SOD activity was decreased; the Bcl­2/Bax ratio was decreased; and cleaved caspase­3 protein expression levels were increased in the IR group. Compared with in the IR group, in the IPO and EM50 groups, MAP and heart rate (HR) were recovered to various extents post­reperfusion; LDH and CK­MB levels were decreased; IL­6, TNF­α and MDA content was decreased; SOD activity was increased; infarct size was reduced; the Bcl­2/Bax ratio was increased; and cleaved caspase­3 protein expression levels were decreased. In conclusion, EM­1 postconditioning was revealed to reduce I/R injury and inhibit myocardial cell apoptosis, which may be associated with reductions in oxidative stress and inflammatory reactions.

Effects of dexmedetomidine postconditioning on myocardial ischemia and the role of the PI3K/Akt-dependent signaling pathway in reperfusion injury.

The present study aimed to determine whether post-ischemic treatment with dexmedetomidine (DEX) protected the heart against acute myocardial ischemia/reperfusion (I/R)­induced injury in rats. The phosphatidylinositol­3 kinase/protein kinase B(PI3K/Akt)­dependent signaling pathway was also investigated. Male Sprague Dawley rats (n=64) were subjected to ligation of the left anterior descending artery (LAD), which produced ischemia for 25 min, followed by reperfusion. Following LAD ligation, rats were treated with DEX (5, 10 and 20 µg/kg) or underwent post­ischemic conditioning, which included three cycles of ischemic insult. In order to determine the role of the PI3K/Akt signaling pathway, wortmannin (Wort), a PI3K inhibitor, was used to treat a group of rats that had also been treated with DEX (20 µg/kg). Post­reperfusion, lactate dehydrogenase (LDH), cardiac troponin I (cTnI), creatine kinase isoenzymes (CK­MB), superoxide dismutase (SOD) and malondialdehyde (MDA) serum levels were measured using an ultraviolet spectrophotometer. The protein expression levels of phosphorylated (p)­Akt, Ser9­p­glycogen synthase kinase­3ß (p­GSK­3ß) and cleaved caspase­3 were detected in heart tissue by western blotting. The mRNA expression levels of B­cell lymphoma 2 (Bcl­2) and Bcl­2­associated X protein (Bax) were detected using reverse transcription­polymerase chain reaction. At the end of the experiment, the hearts were removed and perfused in an isolated perfusion heart apparatus with Evans blue (1%) in order to determine the non­ischemic areas. The risk and infarct areas of the heart were not dyed. As expected, I/R induced myocardial infarction, as determined by the increased serum levels of cTnI, CK­MB and MDA, and the decreased levels of SOD. Post­ischemic treatment with DEX increased the expression levels of p­Akt and p­GSK­3ß, whereas caspase­3 expression was reduced following DEX treatment compared with in the I/R group. Compared with the I/R group, the ratio of Bcl­2/Bax at the mRNA level was elevated in the DEX and ischemic post­conditioning groups, whereas the expression levels of Bax were decreased. Conversely, the effects of DEX were attenuated by Wort. These results indicated that, similar to post­ischemic conditioning, post­ischemic treatment with DEX protects the heart against I/R via the PI3K/Akt­dependent signaling pathway, possibly by activating GSK­3ß.

Rapid prototyping for tissue-engineered bone scaffold by 3D printing and biocompatibility study.

The prototyping of tissue-engineered bone scaffold (calcined goat spongy bone-biphasic ceramic composite/PVA gel) by 3D printing was performed, and the biocompatibility of the fabricated bone scaffold was studied. Pre-designed STL file was imported into the GXYZ303010-XYLE 3D printing system, and the tissue-engineered bone scaffold was fabricated by 3D printing using gel extrusion. Rabbit bone marrow stromal cells (BMSCs) were cultured in vitro and then inoculated to the sterilized bone scaffold obtained by 3D printing. The growth of rabbit BMSCs on the bone scaffold was observed under the scanning electron microscope (SEM). The effect of the tissue-engineered bone scaffold on the proliferation and differentiation of rabbit BMSCs using MTT assay. Universal testing machine was adopted to test the tensile strength of the bone scaffold. The leachate of the bone scaffold was prepared and injected into the New Zealand rabbits. Cytotoxicity test, acute toxicity test, pyrogenic test and intracutaneous stimulation test were performed to assess the biocompatibility of the bone scaffold. Bone scaffold manufactured by 3D printing had uniform pore size with the porosity of about 68.3%. The pores were well interconnected, and the bone scaffold showed excellent mechanical property. Rabbit BMSCs grew and proliferated on the surface of the bone scaffold after adherence. MTT assay indicated that the proliferation and differentiation of rabbit BMSCs on the bone scaffold did not differ significantly from that of the cells in the control. In vivo experiments proved that the bone scaffold fabricated by 3D printing had no acute toxicity, pyrogenic reaction or stimulation. Bone scaffold manufactured by 3D printing allows the rabbit BMSCs to adhere, grow and proliferate and exhibits excellent biomechanical property and high biocompatibility. 3D printing has a good application prospect in the prototyping of tissue-engineered bone scaffold.

[Preparation and characterization of kaolinite-potassium dihydrogen phosphate intercalation composite].

Thepotassium dihydrogenphospiate (KDP) intercalated kaolinite (K-KDP) was prepared by a three-step reaction. Firstly, polar dimethyl sulphoxide (DMSO) was introduced into the layers of kaolinite by ultrasonic method and the product K-DMSO was obtained as precursor; secondly DMSO was replaced by potassium acetate (KAc) and the product K-KAc was gotten as intermediate; finally KAc was replaced by KDP. The intercalation ratio of the final product K-KDP reached 81.3%. The structure of products at differentreaction process was characterized by Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM) in detail. FTIR results showed the existence of P==O in the final product but moved from 1300 to 1201 cm(-1). XRD results documented that the interlayer spacing of kaolinite was enlarged during the whole intercalation reaction. SEM indicated that the agglomeration of kaolinite was destroyed and the particle size distribution became more uniform.

Nasal prosthesis rehabilitation using CAD-CAM technology after total rhinectomy: a pilot study.

PURPOSE: This study describes a nose prosthetic rehabilitation using computer-aided design and manufacturing (CAD-CAM) technology after facial disfigurement because of a total rhinectomy. METHODS: A patient with a total rhinectomy was scheduled for a nasal prosthesis. Based on the 3-D model of the patient's face reconstructed with the CT data, a four-piece mould for the nasal prosthesis was prototyped using a CAD-CAM procedure. Conventional silicone was processed with this physical mould to fabricate the definitive nasal prosthesis. RESULTS: A silicone nasal prosthesis was manufactured. The size, shape, and cosmetic look of the prosthesis were satisfactory and matched the nasal defect area well. CONCLUSIONS: The protocol presented herein illustrates favorable clinical treatment outcomes in the prosthetic rehabilitation after a total rhinectomy by means of CAD-CAM technology.

Comparisons of 2/3Sh estimation technique to computer-assisted planimetric analysis in epidural, subdural and intracerebral hematomas.

OBJECTIVE: The formula 1/2abc was suitable for the estimation of the epidural, acute subdural, most intracerebral and even some chronic subdural hematoma volume, but its accuracy was prone to be affected by some particular shapes of hematomas. In this study, we aimed to validate a more accurate method for the estimation of the epidural, subdural and intracerebral hematoma volume. METHODS: In the present study, hematomas were categorized into the epidural, subdural and intracerebral groups, and every hematoma in three subgroups was respectively estimated with the following methods, including the computer-assisted planimetric analysis (gold standard), 2/3Sh, 1/2abc, 1/3abc and Tada's formula. Moreover, the percentage deviation of the estimated hematoma volume by every method in comparison with gold standard was assessed respectively. RESULTS: Compared with gold standard (39.59 ± 24.47 ml), the formula 2/3Sh (40.55 ± 26.58 ml, P > 0.05) overestimated the epidural hematoma volume by nearly 1% (0.01 ± 0.09, P > 0.05); similarly, the formula 2/3Sh (70.56 ± 49.06 ml, P > 0.05) in comparison with gold standard (69.98 ± 45.99 ml) overestimated the subdural hematoma volume by nearly <1% (-0.00 ± 0.13, P > 0.05). In addition, the intracerebral hematoma volume assessed by the formula 2/3Sh in contrast with gold standard (33.33 ± 33.19 ml) was 33.88 ± 34.39 ml (P > 0.05) with an only 2% (-0.02 ± 0.15, P > 0.05) underestimation. DISCUSSION: The formula 2/3Sh in contrast with other methods was a precise, simple, convenient estimation method, which was suitable for the epidural, subdural and intracerebral hematoma volume.

[Three-dimensional computer aided design for individualized post-and-core restoration].

OBJECTIVE: To develop a method of three-dimensional computer aided design (CAD) of post-and-core restoration. METHODS: Two plaster casts with extracted natural teeth were used in this study. The extracted teeth were prepared and scanned using tomography method to obtain three-dimensional digitalized models. According to the basic rules of post-and-core design, posts, cores and cavity surfaces of the teeth were designed using the tools for processing point clouds, curves and surfaces on the forward engineering software of Tanglong prosthodontic system. Then three-dimensional figures of the final restorations were corrected according to the configurations of anterior teeth, premolars and molars respectively. RESULTS: Computer aided design of 14 post-and-core restorations were finished, and good fitness between the restoration and the three-dimensional digital models were obtained. Appropriate retention forms and enough spaces for the full crown restorations can be obtained through this method. CONCLUSIONS: The CAD of three-dimensional figures of the post-and-core restorations can fulfill clinical requirements. Therefore they can be used in computer-aided manufacture (CAM) of post-and-core restorations.

[Research on the background correction in the non-invasive sensing of glucose by near-infrared spectroscopy].

For the non-invasive blood glucose concentration sensing by the near-infrared spectroscopy, the signal to noise ratio of the optical measurement system is very low. Both the content of glucose in body and the absorption coefficient of glucose in the near-infrared region are quite weak. More over, the structure of spectral noise is complicated and the variation of noise intensity is very large. The background correction is one of the most effective pre-processing methods to improve the signal to noise ratio of the near-infrared optical detection system. In this paper, the theory expression formula of traditional background correction method was induced firstly. Then in order to avoid the influence from the variation of optical characteristics in the sample and the drift in the optical system, the similar background correction method was proposed, that is, the background which has the similar optical characteristics with the sample was chosen as the reference. The in vitro experiments of pure absorption media and scattering media were conducted to validate the effect. The results showed that, for the glucose in the blood plasma solution and Intralipid-2% solution, after the correction of the background which has the similar optical characteristics with the sample, the prediction precision of multivariate model for glucose concentration has been improved by 25.9% and 40.1%, respectively.

[Research of changes in the mechanical properties and curability of composite core materials modified with ultrafine diamond].

OBJECTIVE: As a new kind of reinforcing filler, ultrafine diamond (UFD) is added into photocurable composite core materials. The properties of the materials are then measured to see if there is any improvement. METHODS: Different content of barium glass and UFD were added into resin matrix to fabricate six groups of photocurable composite core materials. For each group of the materials, the flexural strength, Vicker's micro-hardness and depth of cure were measured. Data of the flexural strength and Vicker's micro-hardness was then collected and analyzed by One-Way ANOVA. RESULTS: For the two kinds of composites with barium glass of 60% and 70%, only a small quantity of modified UFD with 0.2% weight percentage could improve the flexural strength of the composites by 34% and 21% respectively, the microhardness was improved by 23% and 30% respectively. The depth of cure of the composite core materials were more than 2 mm, which had reached the demand of the corresponding ISO criteria. The addition of UFD could make the composite core materials darker and grayer. CONCLUSION: Micro-quantity of UFD can improve the mechanical properties of composite resins notably, and it will not affect the curability of the materials, but the defect in the color need to be reformed.

[Application of wavelength selection algorithm to measure the effective component of Chinese medicine based on near-infrared spectroscopy].

Near infrared (NIR) spectroscopy has raised a lot of interest in the pharmaceutical industry because it is a rapid and cost-effective analytical type of spectroscopy with no need for extensive sample preparation, and with the easy-realizable ability of on-line application. The NIR technology can increase the quality control standard of the Chinese medicine and accelerate the entry into the international market. In the present paper, two methods for wavelength selection are applied to the measurement of borneol, one of which is the multiple-chain stepwise, which tends to select many variables in the same area containing valuable information, and the other is the mixture genetic algorithm, which incorporates simulated annealing so as to improve the local searching ability while maintaining the global searching ability. The results present that the number of wavelength is reduced to 16% compared with the original number of wavelength, and the prediction accuracy has increased 47.6%. Therefore, the method of wavelength selection is a good way to enhance the prediction accuracy and simplify the model in NIR region.

[Application of fiducial wavelength method in processing spectra of turbid media].

In the present paper, the authors analyzed the absorption and scattering effects of changing the solution concentration on the spectra, and dealed with the wavelength, where the absorption and scattering effects counteract completely, the fiducial wavelength method can eliminate the perturbation from shift of instrument and temperature, and also can improve predicting ability of the model. The result of utilizing this method to process the spectral data of two sample sets, i. e. intralipid solution and plasma solution with different level glucose, has verified that fiducial wavelength method can improve correlation coefficient and decrease RMSEP of predicting model.

[Measurement of borneol based on near infrared spectroscopy].

Infrared spectroscopy can provide integrated information of samples, and is easy to be applied to on-line control. So quality control specification of Chinese drugs can be improved by utilizing this method for the production of Chinese drugs. This method can accelerate the modernization process of Chinese drugs. Borneol is an effective constituent in lots of active Chinese drugs. The spectral characteristics of borneol in near infrared region were investigated in this paper. The characteristic absorption peaks of bomeol were found by measuring its spectra in near infrared band. There are five absorption peaks of borneol close to 4828, 5003, 5736, 7044 and 8387 cm(-1), respectively. Establishing a partial least square (PLS) model can get optimal results in model building experiment. The predictive results show that the linear relationship between twenty-five samples' predicted values and real values is good with regard to the content of borneol. In calibration model, the root mean square error of prediction (RMSEP) of the content of borneol is 0.28 mg x mL(-1) and the number of the principal components is equal to two. The experimental results show that infrared spectroscopy can be used as a means in the field of quality control of Chinese drugs and the measurement of effective constituents of Chinese drugs.