The role of sirtuins in intervertebral disc degeneration: Mechanisms and therapeutic potential.

Intervertebral disc degeneration (IDD) is one of the main causes of low back pain, which affects the patients' quality of life and health and imposes a significant socioeconomic burden. Despite great efforts made by researchers to understand the pathogenesis of IDD, effective strategies for preventing and treating this disease remain very limited. Sirtuins are a highly conserved family of (NAD+)-dependent deacetylases in mammals that are involved in a variety of metabolic processes in vivo. In recent years, sirtuins have attracted much attention owing to their regulatory roles in IDD on physiological activities such as inflammation, apoptosis, autophagy, aging, oxidative stress, and mitochondrial function. At the same time, many studies have explored the therapeutic effects of sirtuins-targeting activators or micro-RNA in IDD. This review summarizes the molecular pathways of sirtuins involved in IDD, and summarizes the therapeutic role of activators or micro-RNA targeting Sirtuins in IDD, as well as the current limitations and challenges, with a view to provide possible solutions for the treatment of IDD.

RMDGCN: Prediction of RNA methylation and disease associations based on graph convolutional network with attention mechanism.

RNA modification is a post transcriptional modification that occurs in all organisms and plays a crucial role in the stages of RNA life, closely related to many life processes. As one of the newly discovered modifications, N1-methyladenosine (m1A) plays an important role in gene expression regulation, closely related to the occurrence and development of diseases. However, due to the low abundance of m1A, verifying the associations between m1As and diseases through wet experiments requires a great quantity of manpower and resources. In this study, we proposed a computational method for predicting the associations of RNA methylation and disease based on graph convolutional network (RMDGCN) with attention mechanism. We build an adjacency matrix through the collected m1As and diseases associations, and use positive-unlabeled learning to increase the number of positive samples. By extracting the features of m1As and diseases, a heterogeneous network is constructed, and a GCN with attention mechanism is adopted to predict the associations between m1As and diseases. The experimental results indicate that under a 5-fold cross validation, RMDGCN is superior to other methods (AUC = 0.9892 and AUPR = 0.8682). In addition, case studies indicate that RMDGCN can predict the relationships between unknown m1As and diseases. In summary, RMDGCN is an effective method for predicting the associations between m1As and diseases.

Improved Water Collection from Short-Term Fog on a Patterned Surface with Interconnected Microchannels.

Fog harvesting is considered a promising freshwater collection strategy for overcoming water scarcity, because of its environmental friendliness and strong sustainability. Typically, fogging occurs briefly at night and in the early morning in most arid and semiarid regions. However, studies on water collection from short-term fog are scarce. Herein, we developed a patterned surface with highly hydrophilic interconnected microchannels on a superhydrophobic surface to improve droplet convergence driven by the Young-Laplace pressure difference. With a rationally designed surface structure, the optimized water collection rate from mild fog could reach up to 67.31 g m-2 h-1 (6.731 mg cm-2 h-1) in 6 h; this value was over 130% higher than that observed on the pristine surface. The patterned surface with interconnected microchannels significantly shortened the startup time, which was counted from the fog contact to the first droplet falling from the fog-harvesting surface. The patterned surface was also facilely prepared via a controllable strategy combining laser ablation and chemical vapor deposition. The results obtained in outdoor environments indicate that the rationally designed surface has the potential for short-term fog harvesting. This work can be considered as a meaningful attempt to address the practical issues encountered in fog-harvesting research.

Robust structured light 3D measurement method based on polarization-encoded projection patterns.

Fringe projection profilometry (FPP) is widely used in 3D vision measurement because of its high robustness and measurement accuracy. In the case of HDR objects, due to the problem of surface reflectivity, the obtained image will be overexposed. This will cause the sinusoidality of the fringes projected on the surface of the object in the acquired image to be interfered, resulting in a phase error in the calculated wrapped phase. Therefore, a polarization-encoded sinusoidal structured light is proposed to enhance the sinusoidality of the fringe. The phase information contained in the polarized sinusoidal structured light fringe is only related to the polarization state, not to the light intensity. A polarization coding assisted structured light measurement strategy (PASM) is proposed. This method uses polarization coding assisted polarization phase-shifting fringes for phase unwrapping. The angle of the linear polarizer is set to zero in this method, and it does not require rotating the polarizer. It only needs a single exposure to improve the fringe quality and obtain a more stable unwrapping phase. The experimental results show that the obtained polarization fringes have better sinusoidality, and the phase unwrapping can be more accurate. The reconstructed 3D point cloud also does not appear missing and has better accuracy. It is a reliable method for vision measurement of HDR objects.

Serum and urine metabolomics analyses reveal metabolic pathways and biomarkers in relation to nasopharyngeal carcinoma.

RATIONALE: Nasopharyngeal carcinoma (NPC) is a malignant tumor that is endemic in Southeast Asia, North Africa, and southern China. There is an urgent need for effective early diagnosis and treatment of this disease since NPC is currently often detected at advanced stages. METHODS: To reveal the underlying metabolic mechanisms and discover potential diagnostic biomarkers of NPC, we employed ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) and UHPLC-Q-Exactive Orbitrap MS, respectively, to analyze 54 serum samples and 54 urine samples from 27 patients with NPC and 27 healthy control individuals. RESULTS: A total of 1230 metabolites were determined in serum samples, and 181 of the 1230 metabolites were significantly changed in NPC patients. The 181 metabolites were enriched in 16 pathways, including biosynthesis of unsaturated fatty acids, cholesterol metabolism, and ferroptosis. A total of 2509 metabolites were detected in the urine samples. Among them, 179 metabolites were significantly altered in NPC patients, and these metabolites were enriched in eight pathways, including the tricarboxylic acid (TCA) cycle and caffeine metabolism. Seven metabolites, including creatinine and paraxanthine, were found to be significantly changed in both NPC serum and urine samples. Based on them, further biomarker analysis revealed that the panel of three serum metabolites, octanoylcarnitine, creatinine, and decanoyl-l-carnitine, displayed a perfect diagnostic performance (area under the curve [AUC] = 0.973) to distinguish NPC patients from controls, while the other three-metabolite biomarker panel, consisting of stachydrine, decanoyl-l-carnitine, and paraxanthine, had an AUC = 0.809 to distinguish NPC and control in urine samples. CONCLUSION: This work highlights the key metabolites and metabolic pathways disturbed in NPC and presents potential biomarkers for effective diagnosis of this disease.

The role of extreme high humidex in depression in chongqing, China: A time series-analysis.

As global climate change intensifies, people are paying increasing attention to the impact of temperature changes on adverse mental health outcomes, especially depression. While increasing attention has been paid to the effect of temperature, there is little research on the effect of humidity. We aimed to investigate the association between humidex, an index combining temperature and humidity to reflect perceived temperature, and outpatient visits for depression from 2014 to 2019 in Chongqing, the largest and one of the most hot and humid cities of China. We also aimed to further identify susceptible subgroups. A distributed lag non-linear model (DLNM) was used to explore the concentration-response relationship between humidex and depression outpatient visits. Hierarchical analysis was carried out by age and gender. A total of 155,436 visits for depression were collected from 2014 to 2019 (2191 days). We found that depression outpatient visits were significantly associated with extremely high humidex (≥40). The significant positive single-lag day effect existed at lag 0 (RR = 1.029, 95%CI: 1.000-1.059) to lag 2 (RR = 1.01, 95%CI: 1.004-1.028), and lag 12 (RR = 1.013, 95%CI: 1.002-1.024). The significant cumulative adverse effects lasted from lag 01 to lag 014. Hierarchical analyses showed that females and the elderly (≥60 years) appeared to be more susceptible to extremely high humidex. The attributable numbers (AN) and fraction (AF) of extremely high humidex on depression outpatients were 1709 and 1.10%, respectively. Extremely high humidex can potentially increase the risk of depression, especially in females and the elderly. More protective measures should be taken in vulnerable populations.

Association between ambient carbon monoxide levels and hospitalization costs of patients with myocardial infarction: Potential effect modification by ABO blood group.

Previous researches have reported the association between air pollution and various diseases. However, few researches have investigated whether air pollutants are associated with the economic loss resulting from patients' hospitalization, especially the economic loss of hospitalization due to acute cardiovascular events. The purpose of our research was to explore the association between the levels of carbon monoxide (CO), taken as an index of pollution, and the hospitalization costs of myocardial infarction (MI), and the potential effect modification by the ABO blood group. A total of 3237 MI inpatients were included in this study. A multiple linear regression model was used to evaluate the association between ambient CO levels and hospitalization costs of MI patients. Moreover, we performed stratified analyses by age, gender, body mass index (BMI), season, hypertension, and ABO blood types. There was a positive association between the levels of CO in the air and the costs of hospitalization caused by MI. Furthermore, such association was stronger in males, BMI ≥25, <65 years, with hypertension, and non-O blood group. Interestingly, we found the association was particularly significant in patients with blood group B. Overall, our study first found that ambient CO levels could have an impact on the hospitalization costs for MI patients, and those with blood group B can be more sensitive.

Calibration method of line-structured light sensors based on a hinge-connected target with arbitrary pinch angles.

Line-structured light 3D measurement is often used for 3D contour reconstruction of objects in complex industrial environments, where light plane calibration is a key step. In this paper, we propose a calibration method for a line-structured optical system based on a hinge-connected double-checkerboards stereo target. First, the target is moved randomly in multiple positions at any angle within the camera measurement space. Then, by acquiring any one image of the target with line-structured light, the 3D coordinates of the light stripes feature points are solved with the help of the external parameter matrix of the target plane and the camera coordinate system. Finally, the coordinate point cloud is denoised and used to quadratically fit the light plane. Compared with the traditional line-structured measurement system, the proposed method can acquire two calibration images at once; thus, only one image of line-structured light is needed to complete the light plane calibration. There is no strict requirement for the target pinch angle and placement, which improve system calibration speed with high accuracy. The experimental results show that the maximum RMS error of this method is 0.075 mm, and the operation is simpler and more effective to meet the technical requirements of industrial 3D measurement.

More obvious association between short-term ambient nitrogen dioxide and atrial fibrillation outpatient visits in cool seasons: A hospital-based study in northwestern China.

Atrial fibrillation (AF) is the most common sustained heart rhythm disorder associated with high mortality and morbidity. Limited studies have been conducted to assess the relationship between short-term exposure to ambient air pollution and AF attacks. This study aimed to explore the association between short-term ambient nitrogen dioxide (NO2) exposure and outpatient visits for AF in Xi'an, China. Data on daily AF outpatient visits and air pollutants from 2013 to 2019 (2555 days) were obtained. A time-series approach using over-dispersed Poisson generalized additive model (GAM) was employed, and stratified analyses were performed to investigate the potential modifying effects by season, age, and gender. A total of 8307 outpatient visits for AF were recorded. Increased levels of NO2 were associated with increased AF outpatient visits, and the most significant effect estimates were observed at lag 03: A 10 µg/m3 increase of NO2 at lag 03 was related to an elevation of 5.59% (95% CI: 2.67%, 8.51%) in daily outpatient visits for AF. Stratified analyses showed that there were no gender and age difference in the effect of NO2, while more obvious association was observed in cool seasons (October to March) than in warm seasons (April to September). In summary, short-term ambient NO2 exposure can be positively associated with daily outpatient visits for AF, especially in cool seasons. This work provided novel data that the association between air pollutants and AF can vary by seasons, further supporting that the prevention of cardiovascular health effects should be strengthened in winter.

The association between short-term exposure to ambient carbon monoxide and hospitalization costs for bronchitis patients: A hospital-based study.

Ambient carbon monoxide (CO) is associated with bronchitis morbidity, but there is no evidence concerning its correlation with hospitalization costs for bronchitis patients. This study aimed to investigate the relationship between short-term ambient CO exposure and hospitalization costs for bronchitis patients in Chongqing, China. Baseline data for 3162 hospitalized bronchitis patients from November 2013 to December 2019 were collected. Multiple linear regression analysis was used to determine the association, delayed and cumulative, between short-term CO exposure and hospitalization costs. Additionally, subgroup analyses were performed by gender, age, season, and comorbidity. Positive association between CO and hospitalization costs for bronchitis patients was observed. The strongest association was observed at lag 015 days, with per 1 mg/m3 increase of CO concentrations corresponded to 5834.40 Chinese Yuan (CNY) (95% CI: 2318.71, 9350.08; P < 0.001) (845.97 US dollars) increment in hospitalization costs. Stratified analysis results showed that the association was more obvious among those males, elderly, with comorbidities, and in warm seasons. More importantly, there was strongest correlation between CO and bronchitis patients with coronary heart disease. In summary, short-term exposure to ambient CO, even lower than Chinese and WHO standards, can be associated with increased hospitalization costs for bronchitis. Controlling CO exposure can be helpful to reduce medical burden associated with bronchitis patients. The results also suggest that when setting air quality standards and formulating preventive measures, susceptible subpopulations ought to be considered.

Association between short-term ambient nitrogen dioxide and type 2 diabetes outpatient visits: A large hospital-based study.

Type 2 diabetes (T2DM) as a non-communicable disease imposes heavy disease burdens on society. Limited studies have been conducted to assess the effects of short-term air pollution exposure on T2DM, especially in Asian regions. Our research aimed to determine the association between short-term exposure to ambient nitrogen dioxide (NO2) and outpatient visits for T2DM in Chongqing, the largest city in western China, based on the data collected from November 28, 2013 to December 31, 2019. A generalized additive model (GAM) was applied, and stratified analyses were performed to investigate the potential modifying effects by age, gender, and season. Meanwhile, the disease burden was revealed from attributable risk. Positive associations between short-term NO2 and daily T2DM outpatient visits were observed. The strongest association was observed at lag 04, with per 10 µg/m3 increase of NO2 corresponded to increased T2DM outpatient visits at 1.57% [95% confidence interval (CI): 0.48%, 2.65%]. Stronger associations were presented in middle-aged group (35-64 years old), male group, and cool seasons (October to March). Moreover, there were 1.553% (8664.535 cases) of T2DM outpatient visits attributable to NO2. Middle-aged adults, males, and patients who visited in cool seasons suffered heavier burdens. Conclusively, short-term exposure to NO2 was associated with increased outpatient visits for T2DM. Attention should be paid to the impact of NO2 on the burden of T2DM, especially for those vulnerable groups.

Specular flare suppression method for reflective materials based on the optimal polarizing angle.

A specular suppression model on reflective material figures based on polarization information and figure grayscale information is built. The model can optimize the imaging effect of reflective material in a strong light environment to restore the information characteristics of the figure. Taking the workpiece surface of reflective material as the experimental object, figure surfaced information restoration and visual measurement effect analysis were carried out. The experimental results show that the method offered can achieve good suppression of the large-area light spot phenomenon in the imaging of reflective material. The texture contours of the figures are significantly improved, and the imaging indicators in all aspects are further optimized, which verifies the feasibility of the offered method to a certain extent.

Double filtration plasmapheresis for hypertriglyceridemic acute pancreatitis caused by fat overload syndrome.

WHAT IS KNOWN AND OBJECTIVE: Severe hypertriglyceridemia (HTG) can cause acute pancreatitis (AP). CASE SUMMARY: We report a patient with acute lymphoblastic leukaemia who received long-term intravenous parenteral nutrition solution without monitoring of the serum triglyceride (TG) level, which resulted in fat overload syndrome and HTG-AP. WHAT IS NEW AND CONCLUSION: Double filtration plasmapheresis was performed to eliminate the TGs and treat the AP.

Effect of occlusal coverage depths on the precision of 3D-printed orthognathic surgical splints.

BACKGROUND: Precise orthognathic surgical splints are important in surgical-orthodontic treatment. This study aimed to propose a standardized protocol for three-dimensional (3D)-printed splints and assess the precision of splints with different occlusal coverage on the dentition (occlusal coverage depth, OCD), thus optimizing the design of 3D-printed splints to minimize the seemingly unavoidable systematic errors. METHODS: Resin models in optimal occlusion from 19 patients were selected and scanned. Intermediate splints (ISs) and final splints (FSs) with 2-mm, 3-mm, 4-mm, and 5-mm OCDs were fabricated and grouped as IS-2, IS-3, IS-4, IS-5, FS-2, FS-3, FS-4, and FS-5, respectively. The dentitions were occluded with each splint and scanned as a whole to compare with the original occlusion. Translational and rotational deviations of the lower dentition and translational deviations of the landmarks were measured. RESULTS: For vertical translation, the lower dentitions translated inferiorly to the upper dentition in most of the splints, and the translation increased as OCD got larger. Vertical translations of the dentitions in 89.47% of IS-2, 68.42% of IS-3, 42.11% of IS-4, 10.53% of IS-5, 94.74% of FS-2, 63.16% of FS-3, 26.32% of FS-4, and 21.05% of FS-5 splints were below 1 mm, respectively. For pitch rotation, the lower dentitions rotated inferiorly and posteriorly in most groups, and the rotation increased as OCD got larger. Pitch rotations of the dentitions in 100% of IS-2, 89.47% of IS-3, 57.89% of IS-4, 52.63% of IS-5, 100.00% of FS-2, 78.95% of FS-3, 52.63% of FS-4, and 47.37% of FS-5 splints were below 2°, respectively. On the other hand, the transversal and sagittal translations, roll and yaw rotations of most groups were clinically acceptable (translation < 1 mm and rotation < 2°). The deviations of ISs and FSs showed no statistical significance at all levels of coverage (P > 0.05). CONCLUSIONS: A protocol was proposed to generate 3D-printed ISs and FSs with normalized basal planes and standardized OCDs. Deviations of the ISs and FSs were more evident in the vertical dimension and pitch rotation and had a tendency to increase as the OCD got larger. ISs and FSs with both 2-mm and 3-mm OCD are recommendable regarding the precision relative to clinical acceptability. However, considering the fabrication, structural stability, and clinical application, ISs and FSs with 3-mm OCD are recommended for accurate fitting.

Association between short-term ambient air pollution and outpatient visits of anxiety: A hospital-based study in northwestern China.

Anxiety, a common and devastating mental disorder, has raised widespread interests. The impacts of air pollution on physical health are well known, whereas few studies have explored the association of atmospheric pollution, especially short-term air pollution exposure, with the risk of anxiety disorders. In addition, there are increasing concerns in emerging evidence supporting a possible etiological link. Therefore, our aim was to evaluate the relationship between short-term exposure to atmospheric pollutants and anxiety outpatient visits in Xi'an, a city of northwestern China and a metropolis with relatively heavy air pollution. We collected the data of both daily outpatient visits and daily air pollution (SO2, NO2, and PM10) between January 1, 2010 and January 31, 2016 (2222 days). To clarify the association between short-term ambient atmospheric pollution exposure and anxiety outpatient visits, an over-dispersed Poisson generalized additive model was applied by adjusting the day of the week and weather conditions (including temperature, humidity, sunlight hours, and rainfalls). Positive association between gaseous air pollutants (SO2 and NO2) and anxiety daily outpatient visits was observed. Moreover, the largest estimated values of both SO2 and NO2 were evidence at lag 03 (4-day moving average lag), with 10 µg/m3 increase corresponded to the increase of outpatient anxiety visits at 4.11% (95% CI: 2.15%, 6.06%) for SO2 and 3.97% (95% CI: 1.90%, 6.06%) for NO2. However, there was no differences in susceptibility to air pollutants between different genders as well as different ages. Taken together, short-term exposure to ambient air pollutants, especially gaseous air pollutants (NO2 and SO2), can be related to higher risk of anxiety outpatient visits.

Association between short-term ambient air pollution exposure and depression outpatient visits in cold seasons: a time-series analysis in northwestern China.

Depression is known to be one of the most common mental disorders raising global concerns. However, evidence regarding the association between short-term air pollution exposure and risk of development of depression is limited. The aim of this was to assess the relationship between short-term ambient air pollution exposure and depression in outpatient visits in Xi'an, a northwestern Chinese metropolis. Data for air pollutants including particulate matter (PM10), sulfur dioxide (SO2), and nitrogen dioxide (NO2) levels from October 1, 2010 to December 31, 2013 and number of daily depression outpatient visits (92,387 in total) were collected. A time-series quasi-Poisson regression model was adopted to determine the association between short-term air pollutant concentrations and frequency of outpatient visits for depression with different lag models. Consequently, 10 µg/m3 increase of SO2 and NO2 levels corresponded to significant elevation in number of outpatient-visits for depression on concurrent days (lag 0), and this relationship appeared stronger in cool seasons (October to March). However, the association of PM10 was only significant in males aged 30-50 at lag 0. Evidence indicated that short-term exposure to ambient air pollutants especially in cool seasons might be associated with increased risk of outpatient visits for depression.

Sumoylation of PPARγ contributes to vascular endothelium insulin resistance through stabilizing the PPARγ-NcoR complex.

Sumoylation of peroxisome proliferator-activated receptor Î³ (PPARγ) affects its stabilization, sublocalization, and transcriptional activity. However, it remains largely unknown whether PPARγ sumoylation inhibits the transactivation effect, leading to endothelium insulin resistance (IR). To test this possibility, human umbilical vascular endothelial cells (HUVECs) with a 90% confluence were randomly allocated to two batches. One batch was first pretreated with or without vitamin E for 24 hr and the other infected with adenoviruses containing either PIAS1-shRNA (protein inhibitor of activated STAT1-short hairpin RNA) or scramble shRNA. Cells were suffered from high glucose and palmitic acid (PA) exposure for further 48 hr. The levels of PPARγ, p-IKK, IKK, and NcoR (nuclear corepressors) were measured by western blot analysis. The interaction of IKK and PIAS1, as well as the PPARγ sumoylation, were examined by coimmunoprecipitation. The results showed that the exposure of high glucose and PA induced reactive oxygen species (ROS) production and IKK activation in HUVECs, promoting the interaction of IKK and PIAS1 and the sumoylation of PPARγ. However, vitamin E and PIAS1-shRNA partially decreased ROS production and IKK activation induced by high glucose and PA exposure. These data indicate that ROS-IKK-PIAS1 pathway mediates PPARγ sumoylation, leading to endothelium IR via stabilizing PPARγ-NcoR complex. These findings benefit understanding of regulatory networks of insulin signaling, which might provide a potential target to prevent and cure IR-related diseases.

Secreted-Osteopontin Contributes to Brown Adipogenesis In Vitro via a CD44-Dependent Pathway.

Osteopontin (OPN), a secreted glycoprotein, is involved in various pathophysiological processes including immune response, inflammation, tumor formation, and metabolism. OPN exists in 2 forms, secreted-OPN (sOPN) and intracellular-OPN (iOPN). While they might have different biological activities, it remains largely unknown whether sOPN and iOPN induce the differentiation of brown adipocytes. To test this possibility, 3T3-L1 cells were induced by DMI induction with or without recombinant human OPN (rhOPN, 10, 50, 100, 200 µM), respectively. Meanwhile, another batch of 3T3-L1 cells were infected with Ad-GFP-ap2-OPN and followed by DMI differentiation. Subsequently, the infected cells were treated with either anti-CD44 antibody or immunoglobulin G (Ig G). Accumulation of lipid droplets was visualized by Oil red O staining and protein levels were assayed by western blotting analysis. The results showed that sOPN and not rhOPN, notably increased the accumulation of lipid droplets and the expression of brown adipocyte-related genes. Moreover, neutralization of CD44 partially abrogated the effects induced by sOPN. These data demonstrate that sOPN and not rhOPN has the capacity to induce the differentiation of white preadipocytes into brown adipocytes through a CD44-dependent mechanism. The findings might provide a potential target for sOPN to combat obesity.

Preparation and SERS Study of Silver Microstructures with Dendritic Shape.

In the surface ehanced Raman scattering (SERS) technology, not only to improve the making process of SERS substrates, to be fast and easily, but also to enhance the SERS enhance factor, an easy replacement reaction between zinc and silver nitrate solution has been adopted to prepare silver micro-structures SERS-active substrate. The silver micro-substrates have many advantages. These substrates have good stability, well preservation, an easy making method and a fast making process. The surface profile of the silver microparticles is investigated by scanning electron microscope (SEM). The silver microstructures are dendritic shape in a symmetrical fashion with symmetrical distribution. When the time of the replace reaction is 40, 50 and 60 s, respectively, the average lengths of "trunks" in the silver dendritic microsubstractes are about 3, 5 and 10 µm, and the lengths of the "branches" are about 700 nm, 2 µm and 3 µm, respectively. The result shows that the longer time the replacement reaction takes, the longer lengths of the "trunks" and "branches" in the silver dendritic microsubstractes become. With the time of replace reaction increasing, the "trunk" and "branch" in the silver dendritic microsubstractes grow longer and a large amount of nano-level "leaves" grow out from the "branches" of the silver dendritic microsubstractes, so the silver micro size dendrates have nano level structure on surface. In order to investigate the SERS-active substrates application in SERS, a Fourier transform Raman spectrograph with a 1 064 nm laser wavelength is used to measure the SERS spectra. And good SERS spectra have been obtained by using dendritic silver microsubstrates on the silicon chip as a SERS substract, and Rhodamine 6G (R6G) as a molecule probe. It is found that the silver micro-substrates have good Raman characteristics. And comparing these SERS spectra, it gets the conclution that the spectra with best SERS enhance effect are obtained when R6G is obsorbed on the silver dendritic micro-substractes whose preparing time is 40s, and at that time, the analytical enhancement factor for SERS signals is approximately 10(3). And when the silicon ships are dealed with surfactants Polyvinylpyrrolidone (PVP) and keeping the other conditions the same as before, the SERS enhance effect of the spectra becomes better, and the enhancement factor turn to be approximately 10(4). What's more, the silver microstructures can be preserved several monthes under deionized water and the repeatment of the expriment result is well in general.

Reflective long-period fiber grating-based sensor with Sagnac fiber loop mirror for simultaneous measurement of refractive index and temperature.

In this paper, we propose a reflective long-period grating-based sensor with a Sagnac fiber loop mirror (SFLM) for simultaneous measurement of refractive index (RI) and temperature. By cascading the SFLM to the end of a long-period fiber grating (LPFG), the LPFG works as a reflection operation, which is convenient in some applications. Further, the SFLM and the LPFG have different sensitivities to RI and temperature. As a result, RI and temperature measurement can be simultaneously achieved by monitoring the wavelength shifts of the LPFG and the SFLM's dips in the reflection spectrum. Experimental results show that the temperature sensitivity can reach 1.533 nm/°C, and the RI sensitivity is from 16.864 nm/RIU (refractive index unit) to 113.142 nm/RIU when the RI range is from 1.333 to 1.430. The application for 40 km long-distance RI and temperature measurement shows that the sensor has potential application in long-distance sensing.