Direct Observation of HONO Emissions from Real-World Residential Natural Gas Heating in China.

Atmospheric nitrous acid (HONO) is an important precursor of atmospheric hydroxyl radicals. Vehicle emissions and heterogeneous reactions have been identified as major sources of urban HONO. Here, we report on HONO emissions from residential natural gas (RNG) for water and space heating in urban areas based on in situ measurements. The observed HONO emission factors (EFs) of RNG heating vary between 6.03 and 608 mg·m-3 NG, which are highly dependent on the thermal load. The highest HONO EFs are observed at a high thermal load via the thermal NO homogeneous reaction. The average HONO EFs of RNG water heating in winter are 1.8 times higher than that in summer due to the increased thermal load caused by the lower inlet water temperatures in winter. The power-based HONO EFs of the traditional RNG heaters are 1085 times and 1.7 times higher than those of gasoline and diesel vehicles that meet the latest emission standards, respectively. It is estimated that the HONO emissions from RNG heaters in a typical Chinese city are gradually close to emissions from on-road vehicles when temperatures decline. These findings highlight that RNG heating is a non-negligible source of urban HONO emissions in China. With the continuous acceleration of coal-to-gas projects and the continuous tightening of NOx emission standards for vehicle exhaust, HONO emissions from RNG heaters will become more prominent in urban areas. Hence, it is urgently needed to upgrade traditional RNG heaters with efficient emission reduction technologies such as frequency-converted blowers, secondary condensers, and low-NOx combustors.

The Development of a Novel Headspace O2 Concentration Measurement Sensor for Vials.

In the process of manufacture and transportation, vials are prone to breakage and cracks. Oxygen (O2) in the air entering vials can lead to the deterioration of medicine and a reduction in pesticide effects, threatening the life of patients. Therefore, accurate measurement of the headspace O2 concentration for vials is crucial to ensure pharmaceutical quality. In this invited paper, a novel headspace oxygen concentration measurement (HOCM) sensor for vials was developed based on tunable diode laser absorption spectroscopy (TDLAS). First, a long-optical-path multi-pass cell was designed by optimizing the original system. Moreover, vials with different O2 concentrations (0%, 5%, 10%, 15%, 20%, and 25%) were measured with this optimized system in order to study the relationship between the leakage coefficient and O2 concentration; the root mean square error of the fitting was 0.13. Moreover, the measurement accuracy indicates that the novel HOCM sensor achieved an average percentage error of 1.9%. Sealed vials with different leakage holes (4, 6, 8, and 10 mm) were prepared to investigate the variation in the headspace O2 concentration with time. The results show that the novel HOCM sensor is non-invasive and has a fast response and high accuracy, with prospects in applications for online quality supervision and management of production lines.

Highly birefringent hollow-core anti-resonant terahertz fiber with a thin strut microstructure.

A novel highly birefringent and low transmission loss hollow-core anti-resonant (HC-AR) fiber with a central strut is proposed for terahertz waveguiding. To the best of our knowledge, it is the first time that a design of a highly birefringent terahertz fiber based on the hybrid guidance mechanism of the anti-resonant mechanism and the total internal reflection mechanism is provided. Several HC-AR fibers with both ultra-low transmission loss and ultra-low birefringence have been achieved in the near-infrared optical communication band. We propose a HC-AR fiber design in terahertz band by introducing a microstructure in the fiber core which leads to tremendous improvement in birefringence. Calculated results indicate that the proposed HC-AR fiber achieves a birefringence higher than 10-2 in a wide wavelength range. In addition, low relative absorption loss of 0.8% (8.6%) and negligible confinement loss of 1.69×10-4 dB/cm (9.14×10-3 dB/cm) for x-polarization (y-polarization) mode at 1THz are obtained. Furthermore, the main parameters of the fiber structure are evaluated and discussed, proving that the HC-AR fiber possesses great design and fabrication tolerance. Further investigation of the proposed HC-AR fiber also suggests a good balance between birefringence and transmission loss which can be achieved by changing strut thickness to cater numerous applications ideally.

Quantitative analysis of direct oral anticoagulant rivaroxaban by terahertz spectroscopy.

Rivaroxaban, as a direct oral anticoagulant, has been widely used in the treatment and prevention of thrombosis disease (TD). However, even if the same dose of rivaroxaban is taken, different pathophysiological characteristics of TD patients determine the differences in plasma concentrations between individuals, leading to the difficulties of dosage selection and plasma concentration control. Conventional rivaroxaban detection methods, including prothrombin time method, anti-Xa assay and liquid chromatography-tandem mass spectrometry (LC-MS/MS), are not widely used in clinical practice due to the limitations of accuracy, speed and cost. Here, we present a simple quantitative detection method for rivaroxaban by terahertz (THz) spectroscopy. Combining density functional theory (DFT) method and THz spectroscopy, the THz absorption peaks of rivaroxaban and the corresponding low-frequency vibrational modes are studied theoretically and experimentally. We find linear relationships between the amplitudes of these characteristic peaks and the concentrations of rivaroxaban. Based on these linear functions, we can analyse the rivaroxaban concentration with a detection time of 1 minute per test and the lowest detection limit of 2 µmol mL-1. As compared to Raman spectroscopy method (its detection limit is about 80 µmol mL-1), our method has more potential and is practical for the clinical quantitative detection of rivaroxaban as well as other direct oral anticoagulants.

Noninvasive and prospective diagnosis of coronary heart disease with urine using surface-enhanced Raman spectroscopy.

A prospective diagnosis method for coronary heart disease (CHD) using human urine based on surface-enhanced Raman spectroscopy (SERS) is proposed, and could provide valuable information for judging whether to perform percutaneous coronary intervention (PCI) in clinics. Here, urine samples from 87 patients with CHD, including patients with PCI before operation (degree of cardiovascular congestion above 70%) and without PCI (degree of cardiovascular congestion under 70%), and 20 healthy humans were measured using SERS. Principal component analysis (PCA) combined with linear discriminant analysis (LDA) was employed to analyze the SERS spectra, revealing that the classification sensitivity and specificity were 90% and 78.9%, respectively, and the absolute value for loading of PC1 at 1509 cm-1 was the largest. Since platelet-derived growth factor-BB (PDGF-BB) is closely related to CHD, PDGF-BB aqueous solutions with various concentrations (1, 0.5, 0.1, 0.05 and 0.01 ppm) and a mixture of healthy human urine and PDGF-BB aqueous solutions were then investigated in this work, and it was found that the Raman peak at 1509 cm-1 may be attributed to PDGF-BB. Moreover, the measured SERS spectra of all the urine samples from the 87 patients with CHD were compared with the clinical data provided by a hospital, and it was revealed that the appearance of a peak at 1509 cm-1 in the SERS spectra was in good agreement with the results of coronary angiography tests when cardiovascular congestion was above 70%. This indicated that the classification sensitivity and specificity were 87.9% and 87.0%, respectively, through identification of the Raman peak at 1509 cm-1.

Diagnosis and classification of intestinal diseases with urine by surface-enhanced Raman spectroscopy.

Intestinal Disease (ID) is often characterized by clinical symptoms such as malabsorption, intestinal dysfunction, and injury. If treatment is not timely, it will increase the risk of cancer. Early diagnosis of ID is the key to cure it. There are certain limitations of the conventional diagnostic methods, such as low sensitivity and specificity. Therefore, development of a highly sensitive, non-invasive diagnostic method for ID is extremely important. Urine samples are easier to collect and more sensitive to changes in biomolecules than other pathological diagnostic samples such as tissue and blood. In this paper, a diagnostic method of ID with urine by surface-enhanced Raman spectroscopy (SERS) is proposed. A classification model between ID patients and healthy controls (HC) and a classification model between different pathological types of ID (i.e., benign intestinal disease (BID) and colorectal cancer (CRC)) are established. Here, 830 urine samples, including 100 HC, 443 BID, and 287 CRC, were investigated by SERS. The ID/HC classification model was developed by analyzing the SERS spectra of 150 ID and 100 HC, while BID/CRC classification model was built with 300 BID and 150 CRC patients by principal component analysis (PCA)-support vector machines (SVM). The two established models were internally verified by leave-one-out-cross-validation (LOOCV). Finally, the BID/CRC classification model was further evaluated by 143 BID and 137 CRC patients as an external test set. It shows that the accuracy of the classification model validated by the LOOCV for ID/HC and BID/CRC is 86.4% and 85.56%, respectively. And the accuracy of the BID/CRC classification model with external test set is 82.14%. It shows that high accuracy can be achieved with these two established classification models. It indicates that ID patients in the general population can be identified and BID and CRC patients can be further classified with measuring urine by SERS. It shows that the proposed diagnostic method and established classification models provide valuable information for clinicians to early diagnose ID patients and analyze different stages of ID.

Surface-enhanced Raman spectroscopy analysis reveals biochemical difference in urine of patients with perianal fistula.

BACKGROUND & AIMS: Perianal fistulising Crohn's disease (PFCD) is different from the characteristics and outcomes of traditional non-inflammatory bowel disease (IBD) anal fistulas. The presence of perianal disease was a poor prognostic indicator for Crohn's disease (CD) patients and PFCD patients were more likely to bear an increased risk of recurrence. However, the effective and accurate diagnosis methods to early distinguish PFCD from simple perianal fistula were still scarce. The purpose of this study is to develop a non-invasive detecting approach to predict CD in patients with perianal fistulas. METHODS: Data on patients with anal fistulizing disease were collected from July 2020 to September 2020 in two IBD centers. Urine samples from PFCD and simple perianal fistula patients were investigated by surface-enhanced Raman spectroscopy (SERS). Principal component analysis (PCA)-support vector machine (SVM) was utilized to establish classification models to distinguish PFCD from simple perianal fistula. RESULTS: After a case-matched 1:1 selection by age and gender, 110 patients were included in the study. By analyzing the average SERS spectra of PFCD and simple perianal fistula patients, it revealed that there were significant differences in intensities at 11 Raman peaks. The established PCA-SVM model distinguished PFCD from simple perianal fistula with a sensitivity of 71.43%, specificity 80.00% and accuracy 75.71% in the leave-one-patient-out cross-validation. The accuracy of the model in validation cohort was 77.5%. CONCLUSIONS: Investigation of urine samples by SERS helps clinicians to predict Crohn's disease from perianal fistulas, which make patients achieve benefit from a more individualized treatment strategy.

Development and application of an optimal three-wavelength combination for liquid film measurement with absorption spectroscopy.

In the simultaneous measurement of liquid film temperature and thickness based on multi-wavelength absorption spectroscopy, selecting optimal wavelength combinations can significantly improve the measurement accuracy. In the work, the absorption spectra of e-liquid at different temperatures were measured firstly. And ten sets of two-wavelength and three-wavelength combinations were then established based on five specific wavelengths from the absorption spectra, respectively. And the measurement accuracy of all the combinations were validated with a home-made calibration system. Among them, an optimal three-wavelength combination were selected. Finally, the evaporation processes of e-liquid films at three initial thicknesses (921/780/629 µm) on a horizontal quartz plate were then investigated with the optimal combination. The variation trends of film temperature and thickness measured by the combination were consistent with imaging method and thermocouple. It was found that the optimal three-wavelength combination could achieve high accuracy in simultaneous measurement of liquid film temperature and thickness.

Sodium glucose co-transporter 2 (SGLT2) inhibition via dapagliflozin improves diabetic kidney disease (DKD) over time associatied with increasing effect on the gut microbiota in db/db mice.

Background: The intestinal microbiota disorder gradually aggravates during the progression of diabetes. Dapagliflozin (DAPA) can improve diabetes and diabetic kidney disease(DKD). However, whether the gut microbiota plays a role in the protection of DAPA for DKD remains unclear. Methods: To investigate the effects of DAPA on DKD and gut microbiota composition during disease progression, in our study, we performed 16S rRNA gene sequencing on fecal samples from db/m mice (control group), db/db mice (DKD model group), and those treated with DAPA (treat group) at three timepoints of 14weeks\18weeks\22weeks. Results: We found that DAPA remarkably prevented weight loss and lowered fasting blood glucose in db/db mice during disease progression, eventually delaying the progression of DKD. Intriguingly, the study strongly suggested that there is gradually aggravated dysbacteriosis and increased bile acid during the development of DKD. More importantly, comparisons of relative abundance at the phylum level and partial least squares-discriminant analysis (PLS-DA) plots roughly reflected that the effect of DAPA on modulating the flora of db/db mice increased with time. Specifically, the relative abundance of the dominant Firmicutes and Bacteroidetes was not meaningfully changed among groups at 14 weeks as previous studies described. Interestingly, they were gradually altered in the treat group compared to the model group with a more protracted intervention of 18 weeks and 22 weeks. Furthermore, the decrease of Lactobacillus and the increase of norank_f:Muribaculaceae could account for the differences at the phylum level observed between the treat group and the model group at 18 weeks and 22 weeks. Conclusion: We firstly found that the protective effect of DAPA on DKD may be related to the dynamic improvement of the gut microbiota over time, possibly associated with the impact of DAPA on the bile acid pool and its antioxidation effect.

Research on the difference between patients with coronary heart disease and healthy controls by surface enhanced Raman spectroscopy.

Coronary heart disease (CHD) is one of the primary causes of death globally. There are several diagnostic techniques for CHD at present, but they are invasive and with limited accuracy. In the work, measurement of human urine based on surface-enhanced Raman spectroscopy (SERS) was proposed to diagnose CHD. Urine samples of 157 CHD patients and 63 healthy controls (HC) were investigated by SERS. Statistical analysis of the measured data was then performed. It was found that there were intensity differences in nine Raman peaks (1223/1243/1272/1463/1481/1516/1536/1541/1550 cm-1) between CHD and HC in their average SERS spectrum. Furthermore, principal component analysis (PCA)-linear discriminant analysis (LDA) was then utilized to establish a prediction model to classify CHD and HC. It revealed that the accuracy, specificity and sensitivity of the prediction model validated by leave-one-patient-out cross validation (LOPOCV) were 84.09%, 92.06% and 80.89%, respectively. Therefore, the proposed method can be employed as a non-invasive, rapid and accurate tool for CHD diagnosis in clinical application.

The Specific Changes of Urine Raman Spectra Can Serve as Novel Diagnostic Tools for Disease Characteristics in Patients with Crohn's Disease.

PURPOSE: Crohn's disease (CD) is a chronic recurrent intestinal inflammatory disease that requires repeated invasive examinations. Convenient and noninvasive diagnostic tools for CD are lacking. Surface-enhanced Raman spectroscopy (SERS) can rapidly provide specific metabolite information in various samples. Our previous study has showed urine Raman spectrum can distinguish CD patients from healthy controls noninvasively. In this study, we further investigated the value of urine Raman spectra on identifying the disease characterizations in patients with CD. PATIENTS AND METHODS: Urine samples were analyzed by SERS to acquire specific changes of the spectra from 100 active CD (aCD) patients and 88 inactive CD (iCD) patients. The accuracy of classifier models yielded by SERS was assessed by principal component analysis and support vector machine (PCA-SVM) to investigate spectral differences and disease characterizations. RESULTS: Given a panel of 16 specific Raman spectra, the classifier model was established to predict disease activity between patients with aCD and iCD and achieved higher efficacy than fecal calprotectin (AUC value, 0.864 vs 0.596, P=0.02). After leave-one-patient-out cross-validation, the classifier model still obtained 75.5% of accuracy. The correlation analysis showed it had negative correlation with endoscopic results (r=-0.616, P<0.0001). We further established the classifier model in identifying disease location to discriminate colonic-type from ileal-type CD with 63.6% of accuracy with the significantly increased intensity of 1643 cm-1 band, and the model to predict the spectra changes of before and after treatment in tumor necrosis factor inhibitor responders with 91.2% of accuracy with a panel of 11 specific spectra. The metabolic changes of amino acids, proteins, lipids, and other compounds in urine levels were noted by SERS in patients with CD. CONCLUSION: The specific changes of urine Raman spectra can reflect changes in urine metabolism. It has the potential value on being the promising diagnostic tool for disease characterizations in CD patients by a convenient and noninvasive way.

Concentration, optical characteristics, and emission factors of brown carbon emitted by on-road vehicles.

Atmospheric brown carbon (BrC) is a light-absorbing component that affects radiative forcing; however, this effect requires further clarification, particularly with respect to BrC emission sources, chromophores, and optical properties. In the present study, the concentrations, optical properties, and emission factors of organic carbon (OC), water-soluble OC (WSOC), and humic-like substances (HULIS) in fine particulate matter (PM2.5) emitted from vehicles in three road tunnels (the Wucun, Xianyue, and Wenxing tunnels in Xiamen, China) were investigated. The mass concentrations and light absorption of OC, WSOC, and HULIS were higher at the exits of each tunnel than at entrances, demonstrating that vehicle emissions were a BrC source. At each tunnel's exit, the average light absorption contributed by HULIS-BrC to water-soluble BrC (WS-BrC) and total BrC at 365 nm was higher than the corresponding carbon mass concentration contributed by HULIS (HULIS-C) to WSOC and OC, indicating that the chromophores of HULIS emitted from vehicles had a disproportionately high effect on the light absorption characteristics of BrC. The emission factors (EFs) of HULIS-C and WSOC mass concentrations were highest at the Xianyue tunnel; however, the EFs of HULIS-BrC and WS-BrC light absorption were highest at the Wenxing tunnel, indicating that the chromophore composition of BrC was different among the tunnels and that the mass concentration EFs did not correspond directly to the light absorption EFs.

Laser-based diagnostics for the measurement of liquid water film thickness.

Three different diagnostic techniques are investigated for measurement of the thickness of liquid water films deposited on a transparent quartz plate. The methods are based on laser-induced fluorescence (LIF) from low concentrations of a dissolved tracer substance and spontaneous Raman scattering of liquid water, respectively, both excited with 266 nm of radiation, and diode laser absorption spectroscopy (DLAS) in the near-infrared spectral region. Signal intensities are calibrated using liquid layers of known thickness between 0 and 1000 µm. When applied to evaporating liquid water films, the thickness values derived from the direct DLAS and Raman scattering measurements correlate well with each other as a function of time after the start of data recording, while the LIF signal derived thickness values decrease faster with time due to selective tracer evaporation from the liquid. The simultaneous application of the LIF with a tracer-free detection technique can serve as an in situ reference for quantitative film thickness measurements.

Non-invasive diagnosis of Crohn's disease based on SERS combined with PCA-SVM.

Crohn's disease (CD) is an idiopathic chronic inflammatory bowel disease without a cure. Most of the CD patients are firstly diagnosed by invasive endoscopy, and clinical and pathological examinations are further required to confirm the diagnosis. Hence, the development of a non-invasive, rapid and accurate diagnosis method for CD patients is essential. In this study, urine samples from 95 CD patients (including 58 active CD (aCD) patients and 37 inactive CD (iCD) patients) and 48 healthy controls (HC) were investigated by surface-enhanced Raman spectroscopy (SERS). The statistical analysis of the three groups (i.e., CD/HC, aCD/HC and iCD/HC) was performed on the measured data. Principal component analysis (PCA)-support vector machine (SVM) and PCA-linear discriminant analysis (LDA) were then employed to establish classification models to distinguish between patients and HC. For the average SERS spectra of patients and HC, the Raman peaks belonging to lipids, proteins and nucleic acids were stronger in patients than those in HC. It showed that the classification accuracy of CD/HC based on PCA-SVM was higher than that of PCA-LDA (82.5% vs. 69.9%). And the classification accuracy of aCD/HC based on PCA-SVM was higher than that of iCD/HC (86.8% vs. 76.5%). The classification model we established distinguished between aCD and HC with 86.2% sensitivity and 87.5% specificity. It indicates that the metabolic change of patients could be identified by measuring urine with SERS, and aCD and HC could be distinguished more effectively. Our findings are helpful for clinicians to diagnose CD patients and monitor the progress and recurrence of the disease.

Simultaneous measurement of liquid film thickness and temperature on metal surface.

The flow and evaporation of liquid films widely exist in various industrial fields. The investigation into liquid films is essential to design and optimize the relevant industrial processes. In this work, a simultaneous measurement method of liquid film thickness and temperature on metal surface based on diode laser absorption spectroscopy (DLAS) was proposed, and a corresponding measurement system was developed. First, static liquid films of 200-800 µm on the horizontal metal plate were studied, ultrasonic pulse-echo method (UPEM) and thermocouple were employed to compare with DLAS data. It revealed that the relative deviations of film thicknesses and temperatures measured by different methods were 3.3% and 2.0%, respectively. Furthermore, the evaporation processes of static liquid films were investigated. For the liquid films with different initial thicknesses (490.0/624.6/744.5 µm), the average relative deviations of the film thicknesses and temperatures measured by different methods were 0.1%/0.8%/4.1% and 0.1%/2.6%/3.0%, respectively. Finally, the flow processes of liquid films at different initial temperatures (40.0/60.0/80.0 °C) on the inclined metal plate were researched. It was found that the variation trends of the liquid film thicknesses and temperatures measured by different methods were in good agreement. In the stable stages of flow processes, the average relative deviations of liquid film thicknesses and temperatures measured by different methods were 9.0%/8.4%/5.1% and 3.6%/1.2%/2.5%, respectively. This work is helpful to understand the heat and mass transfer mechanisms in the evaporation and flow processes of liquid films.

Optimization of leakage detection system for vials based on two-line tunable diode laser absorption spectroscopy.

The leakage detection system of vials based on two-line water-vapor tunable diode laser absorption spectroscopy (TDLAS) developed in our previous work was first employed to investigate the instantaneous leakage processes of sealed vials. It showed that the leakage states of the vials with medicines cannot be accurately determined in a short time after the opening. Therefore, an optimized system was developed with two-line oxygen TDLAS method by the measurement of defined oxygen leakage coefficient, and it was then utilized to study the instantaneous leakage processes of sealed vials. It revealed that when the stoppers of the sealed vials were opened, the oxygen leakage coefficients increased immediately and then reach stable. It indicated that the optimized system was not affected by the water absorption of medicines. Furthermore, 15 vials with known leakage states were measured. It showed that the oxygen leakage coefficients of fully-open vials were obviously larger than that of sealed vials, and the maximum standard deviation of oxygen leakage coefficients for ten measurements of a single vial was 0.03%. The sealed vials with different leakage degrees were then investigated by inserting the needles with different sizes (0.5/1/2/3.5 mm) into the vials. It revealed that the time required for the oxygen leakage coefficients to reach stable was shorter for the vials with larger leakage degree, i.e., larger needle size inserted. It showed that non-invasive, fast response and high-accuracy leakage detection of vials can be realized by the optimized system.

Development of a two-line DLAS sensor for liquid film measurement.

The simultaneous measurements of multiple parameters (film thickness, temperature, etc.) of the liquid films are crucial for the design and optimization of relevant industrial processes. Here, a sensor based on diode-laser absorption spectroscopy (DLAS) was developed to simultaneously measure liquid water film thicknesses and temperatures by combining two diode lasers at different wavenumber positions, 6718.2 cm-1 and 7040.8 cm-1. Serious beam steering effects can be avoided by adding an integrating sphere to improve the performance of the sensor for the investigations of dynamic films. The measurement accuracies of this sensor were firstly validated by a calibration tool with known film thicknesses and temperatures. It revealed that the averaged deviations between the measured film thicknesses/temperatures and the corresponding known parameters were 4.58% and 1.34%, respectively. The sensor was then employed to study liquid film evaporation processes on a horizontal quartz glass plate. The imaging method and the thermocouple were simultaneously employed to obtain the film thicknesses and temperatures to compare with the DLAS results. It showed that the average evaporation rates of the liquid films were 0.34/0.41/0.57 µm/s at different temperatures (340/360/390 K) of the heat gun outlet, respectively, and the evaporation rates increased with the increasing film temperatures. The whole evaporation process can be tracked with the sensor. Furthermore, the sensor was applied to simultaneously determine the variations of liquid film thicknesses and temperatures in a flow channel. It was found that the film temperatures remained almost constant during passage of low-amplitude surface waves at the film temperatures 308/315/323 K.

Influence of drugs on the prospective diagnostic method for coronary heart disease with urine.

The morbidity of coronary heart disease (CHD) with high risks has been rising in recent years. A novel and noninvasive method based on surface-enhanced Raman spectroscopy (SERS) was proposed by Yang et al. (Analyst 143: 2235, 2018) to prospectively diagnose the arterial blockage by detecting platelet-derived growth factor-BB (PDGF-BB) in urine. Clinically, anti-platelet drugs (such as aspirin, statins and clopidogrel) are often used for ordinary CHD patients or patients with percutaneous coronary intervention (PCI). Therefore, whether the previous developed method can be applied to the CHD patients on long-term medication (more than 6 months) or post-PCI patients was investigated here. Firstly, urine samples of 13 CHD patients on long-term medication (aspirin, rosuvastatin, clopidogrel bisulfate) and 13 post-PCI patients were measured by the proposed method. Clinical data of coronary angiography results provided by Xin Hua Hospital and Yangpu District Central Hospital Antu Branch revealed that these 26 patients were with serious arterial blockage, however, characteristic Raman peak at 1509 cm-1 attributed to PDGF-BB was not observed in the SERS spectra of these 26 patients. In addition, an eight-day follow-up investigation was performed on a CHD patient with PCI three years ago and on long-term medication. It was found that the Raman peak at 1509 cm-1 could be only observed in the third and fourth day after suspending the drugs. Furthermore, SERS spectra of mixed solutions of PDGF-BB and aspirin, rosuvastatin, mixed solutions of these two drugs and clopidogrel bisulfate were analyzed. The Raman peak at 1509 cm-1 was not found in all these spectra, it indicated that all the three kinds of drugs could influence on the SERS signal of PDGF-BB. Therefore, the previous developed method is not suitable for CHD patients on long-term medication and post-PCI patients.

Simultaneous measurement of film thickness, temperature, and mass fraction of urea-water-solutions by multi-wavelength laser absorption spectroscopy.

Quantitative analysis for thickness, temperature, and mass fraction of liquid film is extremely crucial to the relevant industrial processes, but these parameters cannot be determined simultaneously by conventional measurement techniques. In the present work, a novel measurement method based on laser absorption spectroscopy was developed to measure the film temperature, thickness, and mass fraction of urea-water-solutions simultaneously by combining three wavelengths, 1420 nm, 1488 nm, and 1531 nm. Moreover, measurement accuracy of this method was validated by a calibration tool which provided liquid film with known film thickness, temperature, and mass fraction, respectively. It revealed that the deviation between the measured and known parameters with the developed method was 0.86%, 4.58%, and 3.85%, respectively.