Supramolecular gel formation regulated by water content in organic solvents: self-assembly mechanism and biomedical applications

As one of the most important and fruitful methods, supramolecular self-assembly has a significant advantage in designing and fabricating functional soft materials with various nanostructures. In this research, a low-molecular-weight gelator, N,N′-di(pyridin-4-yl)-pyridine-3,5-dicarboxamide (PDA-N4), was synthesized and used to construct self-assembled gels via a solvent-mediated strategy. It was found that PDA-N4 could form supramolecular gels in mixed solvents of water and DMSO (or DMF) at high water fraction (greater than or equal to 50%). By decreasing the water fraction from 50% to 30%, the gel, suspension and solution phases appeared successively, indicating that self-assembled aggregates could be efficiently modulated via water content in organic solvents. Moreover, the as-prepared PDA-N4 supramolecular gels not only displayed solid-like behavior, and pH- and thermo-reversible characteristics, but also showed a solution–gel–crystal transition with the extension of aging time. Further analyses suggested that both the crystal and gel had similar assembled structures. The intermolecular hydrogen bonding between amide groups and the π–π stacking interactions between pyridine groups played key roles in gel formation. Additionally, the release behavior of vitamin B12 (VB₁₂) from PDA-N4 gel (H₂O/DMSO, v/v = 90/10) was evaluated, and the drug controlled release process was consistent with a first-order release mechanism. The human umbilical venous endothelial cell culture results showed that the PDA-N4 xerogel has good cytocompatibility, which implied that the gels have potential biological application in tissue engineering and controlled drug release.

Supramolecular hydrogels with solution–gel–crystal transition, pH- and thermo-reversible characteristics were constructed via a solvent-mediated strategy and applied to cell cultivation and controllable drug release.     

A sensitive fluorescent sensor for the detection of trace water in organic solvents based on carbon quantum dots with yellow fluorescence

The quantitative analysis of trace water in organic solvents has always been a research hotspot, and it is still in the development stage and needs to be continuously developed. In this study, a facile and rapid approach was developed for the preparation of carbon quantum dots (CQDs) with yellow fluorescence emission and ultrahigh absolute fluorescence quantum yields (92.6%). Compared to traditional organic fluorescent molecules, the preparation of CQDs is simpler, faster and more environmentally friendly. It is found that the fluorescent properties of CQDs are excellent in organic solvents and could be quenched by trace water, which makes them a promising material used without any modification for the detection of water in organic solvents. As a result, the as-prepared CQDs were adopted as fluorescent probes for the detection of water in organic solvents (ethanol, tetrahydrofuran, and 1,4-dioxane). The limit of detection was as low as 0.01%. To the best of our knowledge, this is the first time that CQDs have been used as water sensing fluorescent probes in organic solvents. The possible mechanism for trace water detection of the as-prepared CQDs in organic solvents is attributed to the specific water–fluorophore interaction and partially to the increase in polarity of the solvent caused by an increase in water concentration.

A simple fluorescent sensor for water content based on carbon quantum dots with yellow fluorescence was first demonstrated.     

Exploring organic photosensitizers based on hemicyanine derivatives: a sustainable approach for preparation of amide linkages

Hemicyanine derivatives C1–C4 have been synthesized and show strong absorption in the visible region, good water solubility, efficient intersystem crossing, a high singlet oxygen quantum yield and high ability to transport electrons from the donor to acceptor. These hemicyanine derivatives were utilized as photocatalysts in additive/base free oxidative amidation of aromatic aldehydes in mixed aqueous media under visible light irradiation at low catalytic loading. The hemicyanine derivative C4 exhibited recyclability upto four cycles and reusability upto five cycles in oxidative amidation of aromatic aldehydes. Among all the hemicyanine derivatives, C4 shows a high photocatalytic efficiency due to a high singlet oxygen quantum yield. All the mechanism investigations showed involvement of reactive oxygen species generated by the organic triplet photosensitizer based on hemicyanine derivative for carrying out oxidative amidation of aldehyde. Our results will encourage the design of new “metal free” organic photosensitizers and their application in photocatalysis.

Hemicyanine derivatives C1–C4 have been synthesized and utilized as photocatalysts in additive/base free oxidative amidation of aromatic aldehydes in mixed aqueous media under visible light irradiation at low catalytic loading.     

基于动态模板匹配技术的放疗摆位误差测量

本文考虑到病人在放射治疗过程中身体发生变形而使得基于固定模板匹配方法测量重复摆位误差精度降低的问题,提出了基于动态模板匹配的放疗病人重复摆位方法.该方法是对基于CT重建数字射线图像(DRR)作为模板进行匹配的重复摆位技术的改进,将能反映病人体态变化的视频重建三维体表模型作为匹配的模板进行摆位误差的计算.理论研究和实际检验表明,采用动态视频模板匹配的摆位方法,可以在保证摆位精度的同时消除因病人身体变形带来的不利影响.     

A deep community based approach for large scale content based X-ray image retrieval

A computer assisted system for automatic retrieval of medical images with similar image contents can serve as an efficient management tool for handling and mining large scale data, and can also be used as a tool in clinical decision support systems. In this paper, we propose a deep community based automated medical image retrieval framework for extracting similar images from a large scale X-ray database. The framework integrates a deep learning-based image feature generation approach and a network community detection technique to extract similar images. When compared with the state-of-the-art medical image retrieval techniques, the proposed approach demonstrated improved performance. We evaluated the performance of the proposed method on two large scale chest X-ray datasets, where given a query image, the proposed approach was able to extract images with similar disease labels with a precision of 85%. To the best of our knowledge, this is the first deep community based image retrieval application on large scale chest X-ray database.     

Moisture content measurement on Eucalyptus seed for storage

Seed moisture content may significantly affect the storage life of both agricultural and forest species. Seed store managers therefore need an easy and reliable method for routinely checking moisture contents. A robust, portable, easy- to-use electrical seed moisture meter, the Protimeter Grainmini V, was evaluated on samples of Eucalyptus globulus, E. pulchella and E. obliqua seed. Meter readings were well correlated with gravimetric moisture contents ranging from 4.7% to 24.3% of oven dry weight. Relative humidity readings were also made on the equilibrium atmosphere within sealed bags of seed to see whether it might be feasible to derive seed moisture indirectly via relative humidity.

For E. globulus, the fertile seed had gravimetric moisture contents several percent lower than the associated chaff, which normally comprises the bulk of a stored Eucalyptus seed lot. Equations were derived to define the relationship between the overall moisture content and that of the fertile seed, and the way this relationship is affected by the fertile seed/chaff ratio. Fertile seed also gave a higher meter reading than chaff at the same gravimetric moisture content. These effects were much less marked with smaller-seeded eucalypts.

These findings have been incorporated in calibration tables for the electrical meter, which is now used by Forestry Tasmania to screen all Eucalyptus seed prior to and during storage. Results should be generally accurate to within about ± 1 % of oven dry weight.

The concept of deriving seed moisture content indirectly through the equilibrium humidity of the seed atmosphere seems sound in principle but is impractical for this purpose at its present stage of development.     

An indirect analytical approach based on ATR-FTIR spectroscopy for determining the FFA content in vegetable oils

In this study, we developed a novel approach for determining a free fatty acid (FFA) in vegetable oils using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. FFA was converted to carboxylate species by a reaction with phthalimide potassium salt, and the linear relationship between FFA content and ATR-FTIR peak areas at 1541–1616 cm⁻¹ (1595 cm⁻¹ as baseline) was established. Results showed that the R² values obtained during calibration and validation were more than 0.99. The calibration method concurred to within ±0.035% over the range of 0.4% to 4.0% (quantitative determination of the percentage of FFA in oils, expressed as the percentage of oleic acid). In the calibration model, the root mean square error of prediction was 0.0104, the relative error was less than 0.246% and the relative average deviation was 0.386%, respectively. These indexes demonstrated that the calibration model has great accuracy, high precision and good stability. The indirect method established using ATR-FTIR has the advantages of excellent reproducibility, high exactitude, independent of oil type, simple operation and easy cleaning of the instrument surface. The slope of the verification equation between FFA prediction values and American Oil Chemists'' Society''s (AOCS) titration method was close to 1, R² value was more than 0.99. These indicators suggested that the proposed method and the AOCS method have a good correlation through AOCS titration and ATR–FTIR spectroscopy to determine validation samples parallel. In addition, for comparison, when the AOCS titration and ATR-FTIR spectroscopy methods were used for sample validation, the results indicated that the latter method is more reproducible, highly sensitive and has strong anti-disturbance. Therefore, the ATR-FTIR technique can be applied as a simple, highly sensitive, convenient and timely method for the analysis of FFAs in oils.

In this study, we developed a novel approach for determining a free fatty acid (FFA) in vegetable oils using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy.     

基于可变翻转角技术快速测量组织T1值的可行性

目的 探讨可变翻转角结合三维（3D）容积内插快速扰相梯度回波（FSPGR）序列快速测量T1值的可行性。方法 采用不同浓度钆溶液作为模型,以单层反转恢复快速自旋回波（IR-FSE）序列为金标准,比较3D FSPGR可变翻转角组合（2、3个翻转角）和3D容积内插FSPGR可变翻转角组合（2、3、4个翻转角）测量模型T1值的准确性。结果 2、3个可变翻转角FSPGR与IR-FSE测量T1值高度相关（r=0.982和0.975,P均<0.001）;2、3、4个可变翻转角3D容积内插FSPGR与IR-FSE测量T1值亦高度相关（r=0.969、0.970和0.979,P均<0.001）,于不同时间所测得T1值的组内相关系数等于或接近1。结论 可变翻转角结合3D容积内插FSPGR可快速测量组织T1值,准确性及重复性较好。     

消毒剂戊二醛含量测定方法研究

目的 研究消毒剂中戊二醛含量的方法。 方法 利用酸度计法和电位滴定法测定消毒剂中戊二醛的含量,建立测定方法。 结果 酸度计法和电位滴定法在测定消毒剂中戊二醛含量,高、中、低浓度的加标回收率都在98%以上,相对标准偏差都小于1.0%。酸度计法、电位滴定法测定结果与常规指示剂法测定结果之间差异无统计学意义（P＞0.50）。 结论 酸度计法和电位滴定法在测定消毒剂中戊二醛含量,具有精密度好,准确度高的优点,可列入戊二醛电位滴定法含量测定的标准方法。     

A quantitative method for measurement of HL-60 cell apoptosis based on diffraction imaging flow cytometry technique

A quantitative method for measurement of apoptosis in HL-60 cells based on polarization diffraction imaging flow cytometry technique is presented in this paper. Through comparative study with existing methods and the analysis of diffraction images by a gray level co-occurrence matrix algorithm (GLCM), we found 4 GLCM parameters of contrast (CON), cluster shade (CLS), correlation (COR) and dissimilarity (DIS) exhibit high sensitivities as the apoptotic rates. It was further demonstrated that the CLS parameter correlates significantly (R² = 0.899) with the degree of nuclear fragmentation and other three parameters showed a very good correlations (R² ranges from 0.69 to 0.90). These results demonstrated that the new method has the capability for rapid and accurate extraction of morphological features to quantify cellular apoptosis without the need for cell staining.OCIS codes: (000.1430) Biology and medicine, (170.1530) Cell analysis     

Validation of a Doppler technique for beat-to-beat measurement of cardiac output

We have measured aortic flow in the ascending aorta in man with a Bach-Simpson BVM 202 blood velocity meter, and aortic root diameter by M-mode echocardiography, and thus derived beat-to-beat cardiac output (Q). We tested the technique in 21 patients (53 comparisons) with various cardiovascular problems against a thermodilution method, and in four normal subjects at rest and two levels of exercise (50 and 100 W) against a nitrous oxide rebreathing method. We obtained excellent overall correlation in a range of 0.5-10 litres/min (r = 0.98, n = 77, sy,x = 0.48 litre/min), the formula for the least squares regression being: (Q Doppler) = 0.95 (Q Thermodilution/N2O) + 0.11 litre/min. The Doppler signal is sufficiently noise-free to obtain maximum acceleration of flow from the first derivative of velocity.     

Stadiometry: on measurement technique to reduce variability in spine shrinkage measurement

OBJECTIVE. To test the effect of two measurement techniques for repeated measures of spine height using stadiometry following five experimental activity conditions.DESIGN. Six subjects were repeatedly measured while they stepped in and out of the stadiometer for each pair of measures and again on another day when they remained in place in the stadiometer for all 10 measures.RESULTS. There was much greater variability in height measures with the "in-out" method while the "in place" method demonstrated a steady shrinkage over the 3-3.5 min required to obtain the repeated measures.RelevanceContrary to popular practice, leaving a subject in the stadiometer during repeated measures includes the shrinkage that occurs over the 3-3.5 min of measurement when standing and reduces random variation due to posture change.     

Evaluation of a modified piezoresistive technique and a water-capsule technique for direct and continuous measurement of intra-abdominal pressure in a porcine model

OBJECTIVE: Intravesical pressure measurement is considered to be the gold standard for the assessment of intra-abdominal pressure. However, this method is indirect and depends on a physiologic bladder function. We evaluated a modified piezoresistive technique and a water-capsule technique for direct and continuous intra-abdominal pressure measurement. DESIGN: Experimental study. SETTING: Animal research laboratory. SUBJECTS: Eleven male domestic pigs. INTERVENTIONS: In anesthetized and mechanically ventilated animals, CO2 was insufflated to stepwise increase the intra-abdominal pressure to 30 mm Hg. Pressure was then held constant for 9 hrs followed by decompression. Piezoresistive measurement and water-capsule measurement probes were placed intra-abdominally. MEASUREMENTS AND MAIN RESULTS: Readings of intravesical pressure measurement, piezoresistive measurement, and water-capsule measurement were taken hourly. Mean difference to insufflator readings, confidence intervals, and limits of agreement were calculated. Differences between applied pressure and intra-abdominal pressure readings were assessed using a two-factor analysis of variance. No significant differences between methods could be observed. During stepwise pressure increase, limits of agreements were -3.6 to 3.6 mm Hg. Confidence intervals were -3.4 to 3.5 (intravesical pressure measurement), -1.6 to 1.5 (piezoresistive measurement), and 0.5 to 2.9 mm Hg (water-capsule measurement). In the presence of constantly elevated intra-abdominal pressure, limits of agreement ranged from -8.2 to +8.2 mm Hg. Confidence intervals were -0.4 to 6.2 (intravesical pressure measurement), -0.2 to 2.7 (piezoresistive measurement), and 1.1 to 5.1 mm Hg (water-capsule measurement). CONCLUSIONS: Both piezoresistive measurement and water-capsule measurement had smaller confidence intervals than intravesical pressure measurement, indicating higher precision, whereas water-capsule measurement had a significant offset. Piezoresistive measurement could be the most suitable device for continuous direct intra-abdominal pressure monitoring in specific patients.     

Local regression: a new approach for measurement system comparison analysis

Abstract A new graphical approach for analysis of measurement system comparison studies is proposed. Unlike the established linear regression and Bland-Altman analysis, it does not depend on the assumption of a linear relationship. We review the established analysis approaches and propose a difference plot with non-parametric regression as an adequate tool to describe the relationship between two measurement systems. Along with pre-defined level-dependent acceptance limits, this approach may provide evidence for metrological equivalence between two measurement systems. Several data examples are given to illustrate this approach. Clin Chem Lab Med 2008;46:1211-9.     

An online surface water COD measurement method based on multi-source spectral feature-level fusion

To overcome the shortcomings of single or multi-wavelength ultraviolet-visible (UV-Vis) absorbance spectroscopic methods, fluorescence spectroscopic or wet chemistry methods for chemical oxygen demand (COD) measurement, an online detection method based on multi-source spectral feature-level fusion was developed and evaluated. In this method, UV-Vis absorbance spectra (deuterium-halogen lamp as light source) and fluorescence emission spectra (405 nm wavelength laser as excitation source) were measured online by a spectrophotometer (PG2000-Pro-Ex, Ocean Optics). Discrete wavelet transform (DWT) and a successive projections algorithm (SPA) were utilized to realize signal de-noising and feature extraction on the two types of spectra, respectively. Feature-level fusion and least-square support vector regression (LS-SVR) were used to establish the COD measurement model. Through comparison of experiments and results, it is shown that the proposed method has a good performance on both noise tolerance and measurement accuracy.

To overcome the shortcomings of UV-Vis absorbance spectroscopic methods, fluorescence spectroscopic methods or wet chemistry methods for COD measurement, an online detection method was developed and evaluated.     

Palliative care curriculum development: a model for a content and process-based approach

To ensure its success, a new curriculum has to meet the needs of learners, patients, and the institution. A review of the literature indicates that despite a tremendous need for palliative care services and a lack of appropriate knowledge and attitudes among physicians, few palliative care curricula for medical residents have been developed. Most are developed by national organizations, and as a result can not meet the individual needs of different institutions. This paper outlines the process of developing a palliative care curriculum in the context of available institutional resources that meets the learners' needs. The development of a curriculum can be divided into four phases: needs assessment, curricular design, implementation, and evaluation. Content (curricular content, instructional strategies and available resources for the curriculum and the developmental process) and process (methods through which the curriculum is developed and institutional issues are addressed) issues that are pertinent to the successful completion of each phase are discussed. Two hypothetical institutions are used to illustrate relevant issues. Methods that have been successfully used to develop residency curricula are discussed.     

Estimation of atmospheric water vapour content from direct measurements of radiance in the thermal infrared region

Atmospheric water vapour content is a required parameter in thermal infrared (TIR) to carry out processes such as atmospheric correction or retrieving atmospheric factors (downwelling or upwelling irradiance, transmittance of the atmosphere and so on). This study proposes an alternative method to the ones already in use to measure water vapour content from direct measurements of downwelling atmospheric radiance in the TIR range. It was possible to estimate a linear relationship between atmospheric water vapour and downwelling atmospheric radiance using a simulated study, based on data from a radiosounding database. A subsequent validation concludes that it is possible to obtain water vapour content with an uncertainty of 0.5 cm using in situ measurements of downwelling atmospheric radiance in the TIR range of 11.5–12.5 μm.     

Curve aligning approach for gait authentication based on a wearable accelerometer

Gait authentication based on a wearable accelerometer is a novel biometric which can be used for identity identification, medical rehabilitation and early detection of neurological disorders. The method for matching gait patterns tells heavily on authentication performances. In this paper, curve aligning is introduced as a new method for matching gait patterns and it is compared with correlation and dynamic time warping (DTW). A support vector machine (SVM) is proposed to fuse pattern-matching methods in a decision level. Accelerations collected from ankles of 22 walking subjects are processed for authentications in our experiments. The fusion of curve aligning with backward-forward accelerations and DTW with vertical accelerations promotes authentication performances substantially and consistently. This fusion algorithm is tested repeatedly. Its mean and standard deviation of equal error rates are 0.794% and 0.696%, respectively, whereas among all presented non-fusion algorithms, the best one shows an EER of 3.03%.