Fano-like Resonance due to Interference with Distant Transitions.

Narrow optical resonances of atoms or molecules have immense significance in various precision measurements, such as testing fundamental physics and the generation of primary frequency standards. In these studies, accurate transition centers derived from fitting the measured spectra are demanded, which critically rely on the knowledge of spectral line profiles. Here, we propose a new mechanism of Fano-like resonance induced by distant discrete levels and experimentally verify it with Doppler-free spectroscopy of vibration-rotational transitions of CO_{2}. The observed spectrum has an asymmetric profile and its amplitude increases quadratically with the probe laser power. Our results facilitate a broad range of topics based on narrow transitions.

Cavity-enhanced saturated absorption spectroscopy of the (30012) - (00001) band of 12C16O2.

The (30012) ← (00001) band of 12C16O2 in the 1.6 µm region is used for satellite observation of carbon dioxide in the Earth's atmosphere. Here, we report a Doppler-free spectroscopy study of this band with comb-locked wavelength-modulated cavity-enhanced absorption spectroscopy. Frequencies of 18 transitions with the rotational quantum numbers up to 42 were determined with sub-kHz accuracy, corresponding to a fractional uncertainty at the 10-12 level. With this precision, we revealed an anomalous decrease of the line shift and an increase of the line broadening for the Lamb dips of CO2 in the low-pressure regime compared to values obtained from Doppler-limited spectra at higher pressures.

Comb-locked cavity-assisted double-resonance molecular spectroscopy based on diode lasers.

Interactions between a molecule and two or more laser fields are of great interest in various studies, but weak and highly overlapping transitions hinder precision measurements. We present the method of comb-locked cavity-assisted double resonance spectroscopy based on narrow-linewidth continuous-wave lasers, which allows for state-selective pumping and probing of molecules. By locking two near-infrared diode lasers to one cavity with a finesse at the order of 105, we measured all three types of double resonances. Carbon monoxide molecules with selected speeds along the laser beam were excited to vibrationally excited states, and absorption spectra with sub-MHz linewidths were observed. Positions of double resonance transitions were determined with an accuracy of 3.7 kHz, which was verified by comparing to Lamb-dip measurements. The present work paves the way to the pump-probe study of highly excited molecules with unprecedented precision.

Dispersion-like lineshape observed in cavity-enhanced saturation spectroscopy of HD at 1.4 µm.

Precision measurement of ro-vibrational transitions in the electronic ground state of the hydrogen molecule can be used to test quantum electrodynamics and also to determine the dimensionless proton-to-electron mass ratio. Saturation spectroscopy of the 2-0 overtone transitions of hydrogen deuterium (HD) were measured with three cavity-enhanced spectroscopy methods. With a sensitivity at the 10-13cm-1 level, we revealed a dispersion-like lineshape instead of a conventional Lamb "dip," which explains the significant discrepancy among previous independent measurements. The spectra can be fit well by using the Fano profile. Centers of R(1) and R(3) lines were determined as 217 105 182 111 (19)stat(240)syskHz and 220 704 305 234 (20)stat(240)syskHz, respectively.

Comb-locked cavity ring-down spectroscopy with variable temperature.

Temperature dependence of molecular absorption line shape is important information for spectroscopic studies and applications. In this work, we report a comb-locked cavity ring-down spectrometer employing a cryogenic cooler to perform absorption spectroscopy measurements at temperatures between 40 K and 300 K. As a demonstration, we recorded the spectrum of the R(0) line in the (2-0) band of HD at 46 K. The temperature was also confirmed by the Doppler width of the HD line. Spectra of CH4 near 1.394 µm were also recorded in a wide temperature range of 70-300 K. Lower-state energies of methane lines were analyzed by fitting these spectra, which can be directly compared with the HITRAN and TheoReTS databases. Considerable deviations were observed, indicating the need to investigate the assignments of the methane lines in this region.

FOXF2 aggravates the progression of non-small cell lung cancer through targeting lncRNA H19 to downregulate PTEN.

OBJECTIVE: To illustrate the role of FOXF2 in the aggravation of the progression of non-small cell lung cancer (NSCLC) by targeting long non-coding RNA (lncRNA) H19 to down-regulate the gene of phosphate and tensin homolog deleted on chromosome ten (PTEN). PATIENTS AND METHODS: The relative levels of FOXF2 and H19 in NSCLC tissues and adjacent normal tissues were detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The correlation between the expression levels of FOXF2 and H19 was analyzed. Kaplan-Meier curves were depicted for uncovering the prognostic value of FOXF2 in NSCLC patients. The proliferative and migratory abilities of A549 cells influenced by FOXF2 were also assessed. The interaction between FOXF2 and H19 was evaluated through chromatin immunoprecipitation (ChIP) assay and Western blot, so did the association between H19 and PTEN. Finally, rescue experiments were conducted to explore the role of FOXF2/H19/PTEN axis in regulating the viability and migration of A549 cells. RESULTS: FOXF2 and H19 were upregulated in NSCLC and a positive correlation was observed between the two genes. High level of FOXF2 indicated a worse prognosis in NSCLC patients. The knockdown of FOXF2 attenuated the proliferative and migratory abilities of A549 cells. FOXF2 could bind to the promoter region of H19 and accelerated its transcription. Moreover, H19 could recruit EZH2 to bind to PTEN. The overexpression of H19 could reverse the regulatory effects of FOXF2 on the viability and migration of A549 cells. CONCLUSIONS: FOXF2 was upregulated in NSCLC. It accelerated the proliferative and migratory abilities of the NSCLC cells by targeting H19 to downregulate PTEN, thus aggravating the progression of NSCLC.

[Association of ICOS and CD28 single nucleotide polymorphisms with pulmonary tuberculosis susceptibility].

Objective: To investigate the association of inducible co-stimulator (ICOS) and CD28 gene polymorphisms with pulmonary tuberculosis susceptibility. Methods: In this case-control study, from Mar 2015 to Sep 2016, peripheral venous blood of 100 pulmonary tuberculosis patients (pulmonary tuberculosis group) in the Jintan People's Hospital of Changzhou and 100 community physical examination volunteers (health control group) were collected. A total of 56 single nucleotide polymorphisms (SNP) in ICOS and CD28 sequences were selected and SNP genotype and allele frequency were analyzed using the next-generation sequencing technology. Association of these SNP with pulmonary tuberculosis susceptibility was investigated using linkage disequilibrium (LD) analysis and genetic models. Results: Among these 56 SNP, 23 SNP with Hardy-Weinberg equilibrium P (HWE-P) value<0.001 or minimum allele frequency<0.05 were kicked out. The frequencies of T allele and TT genotype of ICOS gene SNP locus (rs55663036), and GG genotype of CD28 gene locus (rs45620941) in tuberculosis group were significantly higher than those in healthy control group (all P<0.05). There was a strong linkage imbalance between rs45620941 at CD28 locus and rs56262258 (r(2)=0.757). Conclusion: The polymorphisms of rs55663036 of ICOS gene and rs45620941 of CD28 gene are significantly associated with the risk of pulmonary tuberculosis.

Frequency metrology of molecules in the near-infrared by NICE-OHMS.

Noise-immune cavity enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) is extremely sensitive in detecting weak absorption. However, the use of NICE-OHMS for metrology study was also hindered by its sensitivity to influence from various experimental conditions such as the residual amplitude modulation. Here we demonstrate to use NICE-OHMS for precision measurements of Lamb-dip spectra of molecules. After a dedicated investigation of the systematic uncertainties in the NICE-OHMS measurement, the transition frequency of a ro-vibrational line of C2H2 near 789 nm was determined to be 379 639 280 915.3±1.2 kHz (fractional uncertainty 3.2 × 10-12), agreeing well with, but more accurate than, the value determined from previous cavity ring-down spectroscopy measurements. The study indicates the possibility to implement the very sensitive NICE-OHMS method for frequency metrology of molecules, or a molecular clock, in the near-infrared.

Potential use of two filter media in constructed wetlands for simultaneous removal of As, V and Mo from alkaline wastewater - Batch adsorption and column studies.

The potential to use water treatment sludge and bauxite as active filter media in constructed wetlands to remove As, V and Mo from alkaline drainage originating from seawater-neutralized bauxite processing residue was evaluated in laboratory batch and column studies. Batch adsorption studies showed that increasing the electrolyte concentration from 0.01 to 0.30 M NaCl (the typical electrolyte strength of the drainage) increased adsorption of all three oxyanions onto both media while increasing initial pH from 6.7 to 8.3 (the typical pH of drainage) and using granules (1-2 mm dia.) rather than ground material (<0.2 mm) both decreased adsorption. Kinetic studies showed that while ionic strength had little effect on the contact time required to reach maximum adsorption, increased initial pH increased the time to reach maximum adsorption for Mo on both media and increased particle size increased the time required for maximum adsorption of all three oxyanions onto both media. In batch experiments, at initial elemental concentrations of 1 and 50 mg L-1, adsorption from multi-element solutions (compared with single element ones) was reduced in the order: Mo ¼â€¯As > V. In continuous flow column studies from single element solutions (1 mg L-1), breakthrough curves for Mo occurred first and greater than three times more eluent passed through the columns before breakthrough of V and then As occurred. When multi-element solutions were used, less volume of eluent was required for breakthrough of all three anions and the volume required before breakthrough of As was greatly reduced compared to that for V. The possibility that the strong ability of V to compete with As and particularly Mo could cause desorption of previously adsorbed Mo and As and their movement through a wetland filter needs to be further investigated. It was concluded that molybdate is the least strongly held oxyanion and that a decrease in solution pH within the wetland would greatly improve Mo removal efficiency.

Comb-locked cavity ring-down saturation spectroscopy.

We present a new method of comb-locked cavity ring-down spectroscopy for the Lamb-dip measurement of molecular ro-vibrational transitions. By locking both the probe laser frequency and a temperature-stabilized high-finesse cavity to an optical frequency comb, we realize saturation spectroscopy of molecules with kilohertz accuracy. The technique is demonstrated by recording the R(9) line in the υ = 3 - 0 overtone band of CO near 1567 nm. The Lamb-dip spectrum of such a weak line (transition rate 0.0075 s-1) is obtained using an input laser power of only 3 mW, and the position is determined to be 191 360 212 770 kHz with an uncertainty of 7 kHz (δν/ν∼3.5×10-11), which is currently limited by our rubidium clock.

Transdifferentiated Monocytes: a Novel Source of Lymphatic Endothelial-like Cells.

Although monocytes have previously been demonstrated to contribute to lymphatic vessel formation in vivo, monocyte transdifferentiation into lymphatic endothelial cells and the specific conditions required remain unclear. In this study, monocyte cultures isolated from human peripheral blood were stimulated to transdifferentiate into lymphatic endothelial cells under specific in vitro induction conditions. These results demonstrate primary isolates of CD14 (+) monocytes express low levels of lymphatic endothelial cell specific markers or pan-endothelial markers under routine culture conditions. Using fibronectin (FN) coated flasks and EGM-2 supplemented culture medium, monocytes were induced to express lymphatic endothelial markers Prox-1, VEGFR-3, LYVE-1, Podoplanin, and pan-endothelial markers vWF, CD144, and VEGFR-2. Furthermore, using the FN/EGM-2/lipopolysaccharide (LPS) culture conditions, monocytes displayed dramatically increased expressions of Prox-1, VEGFR-3, Podoplanin, LYVE-1 and vWF, while the expression of CD144 and VEGFR-2 sharply decreased. In addition, VEGF-C secretion by monocytes exposed to fibronectin coated plates with EGM-2 medium with FN/EGM-2/LPS in vitro was significantly increased over levels seen in routine culture conditions. These findings demonstrate that monocytes can be induced to undergo transdifferentiation becoming more lymphatic endothelial-like cells and increase their VEGF-C production in an FN/EGM-2/LPS environment.

3-D imaging of islets in obesity: formation of the islet-duct complex and neurovascular remodeling in young hyperphagic mice.

BACKGROUND: Obesity and insulin resistance lead to islet hyperplasia. However, how the islet remodeling influences the pancreatic environment and the associated neurovascular networks is largely unknown. The lack of information is primarily due to the difficulty of global visualization of the hyperplasic islet (>200 µm) and the neurovascular environment with high definition. METHODS: We modulated the pancreatic optical property to achieve 3-dimensional (3-D) whole-islet histology and to integrate transmitted light microscopy (which provides the ground-truth tissue information) with confocal fluorescence imaging. The new optical and imaging conditions were used to globally examine the hyperplastic islets of the young (2 months) obese db/db and ob/ob mice, which otherwise cannot be easily portrayed by the standard microtome-based histology. The voxel-based islet micrographs were digitally processed for stereo projection and qualitative and quantitative analyses of the islet tissue networks. RESULTS: Paired staining and imaging of the pancreatic islets, ducts and neurovascular networks reveal the unexpected formation of the 'neuro-insular-ductal complex' in the young obese mice. The complex consists of the peri- and/or intra-islet ducts and prominent peri-ductal sympathetic nerves; the latter contributes to a marked increase in islet sympathetic innervation. In vascular characterization, we identify a decreased perivascular density of the ob/ob islet pericytes, which adapt to ensheathing the dilated microvessels with hypertrophic processes. CONCLUSIONS: Modulation of pancreatic optical property enables 3-D panoramic examination of islets in the young hyperphagic mice to reveal the formation of the islet-duct complex and neurovascular remodeling. On the basis of the morphological proximity of the remodeled tissue networks, we propose a reactive islet microenvironment consisting of the endocrine cells, ductal epithelium and neurovascular tissues in response to the metabolic challenge that is experienced early in life.

Longitudinal assessment of oxytocin efficacy on bone and bone marrow fat masses in a rabbit osteoporosis model through 3.0-T magnetic resonance spectroscopy and micro-CT.

UNLABELLED: This study aims to longitudinally assess the effect of oxytocin on bone and bone fat masses using micro-CT, in vivo magnetic resonance spectroscopy (MRS), and histopathological adipocyte quantification. Early in vivo oxytocin (OT) treatment to the osteoporosis (OP) rabbit model may reliably inhibit bone degeneration and reduce bone marrow fat accumulation by decreasing marrow adipocyte size and density. INTRODUCTION: This study aims to longitudinally assess the effect of early OT treatment on bone and bone fat masses in a rabbit OP model by comparing the results of MRS and micro-CT with histopathological findings. METHODS: Sixty 20-week-old female rabbits were randomly assigned into three groups. The control and OP groups were subjected to either sham surgery or bilateral ovariectomy (OVX). The OT group was subcutaneously injected with OT daily from the second week after OVX for 8 weeks. The left proximal femurs of the rabbits were evaluated through MRS, micro-CT, and histopathological examination at 0, 4, 8, 10, and 12 weeks after operation. Differences in fat fraction (FF) values, micro-CT parameters, and calculated pathological marrow adipocytes among three groups were analyzed. RESULTS: The FF values of the OP group significantly increased (p = 0.019), but the tissue mineral density (TMD) decreased (p = 0.037) from eighth week compared with those of the control group. The FF values of the OT group significantly decreased (p = 0.044), but the TMD values increased (p = 0.042) from eighth week compared with those of the OP group. The adypocyte diameter of the OT group significantly decreased (p = 0.041) from eighth week and then adypocyte density did so too from tenth week, compared with those of the OP group at the same time point. No difference in adypocyte calculation was found between the OT and control groups until the 12th week after operation. CONCLUSION: Early in vivo OT treatment slowed down bone deterioration and reduced bone marrow adiposity accumulation in a rabbit OP model, which is consistent with pathologic findings. OT treatment is a promising preventive OP therapy.

Potential for use of industrial waste materials as filter media for removal of Al, Mo, As, V and Ga from alkaline drainage in constructed wetlands--adsorption studies.

The potential to remove Al, Mo, V, As and Ga from alkaline (pH 8.0-8.6) drainage originating from seawater neutralized bauxite processing residue storage areas using constructed wetland technology was studied in a laboratory study. Bauxite processing residue sand, bauxite, alum water treatment sludge and blast furnace slag were investigated as potential active filter materials. Al was shown to precipitate as Al(OH)3 in the pH range 7.0-8.0 in aqueous solution and 6.0-8.5 in the presence of silica sand particles that provided a surface for nucleation. For V As Mo and Ga, adsorption to the surfaces of the adsorbents decreased greatly at elevated pH values (>pH 6-9). Water treatment sludge and bauxite had a greater ability to adsorb V, As and Mo at high pH (As and V at pH 7-9 and Mo at pH 5-7) than processing sand and slag. Adsorption isotherm data for As and V onto all four adsorbent than processing sand and slag. Adsorption isotherm data for As and V onto all four adsorbent materials fitted equally well to the Langmuir and Freundlich equations but for Ga, and to a lesser extent Mo, the Freundlich equation gave higher R(2) values. For all four ions, the maximum adsorption capacity (Langmuir value qmax) was greatest for water treatment sludge. Bauxite adsorbed more Mo, Ga and V than residue sand or slag. The pseudo-second order equation gave a better fit to the experimental kinetic data than the pseudo-first order model suggesting that chemisorption rather than diffusion/exchange was the rate limiting step to adsorption. It was concluded that water treatment sludge and bauxite were the most effective adsorbents and that for effective removal of the target ions the pH of the drainage water needs to be decreased to 6.0-7.0.

Autoimmune comorbid diseases associated with lichen planus: a nationwide case-control study.

BACKGROUND: Lichen planus (LP) is a chronic inflammatory disorder with unknown aetiology. The association between LP and various autoimmune diseases has been reported, but nationwide study of the relationship of LP with associated diseases is quite limited. OBJECTIVE: Our study aims to clarify the association between LP and a variety of autoimmune diseases in Taiwanese. METHODS: Data were obtained from the National Health Insurance Research Database (NHIRD) of Taiwan from 1997 to 2011. In total, 12,427 patients with LP and 49,708 age- and gender-matched controls were enrolled. RESULTS: Among patients with LP, there were significant associations with systemic lupus erythematosus (SLE) (multivariate odds ratio [mOR]: 2.87; 95% CI: 1.97-4.17), Sjögren's syndrome (mOR: 3.75; 95% CI: 2.66-5.28), dermatomyositis (mOR: 6.34; 95% CI: 1.82-22.16), vitiligo (mOR: 2.09; 95% CI: 1.31-3.32) and alopecia areata (mOR: 2.82; 95% CI: 2.20-3.62). On gender-stratified analyses, SLE and alopecia areata were significantly associated with LP in both genders. The association with Sjögren's syndrome was significant only in female patients. The associations with dermatomyositis and vitiligo became insignificant in both genders. CONCLUSION: Lichen planus is associated with various autoimmune diseases. Further study is required to elucidate the possible underlying mechanisms and roles of autoimmunity in the aetiology of LP.

The natural course of early-onset atopic dermatitis in Taiwan: a population-based cohort study.

BACKGROUND: Atopic dermatitis (AD) often manifests in early childhood and has variable disease course among individual patients. Previous studies regarding the natural course of AD have usually been of small sample size and were not based on nationwide populations. OBJECTIVES: We aimed to find out the disease duration and remission rate of children with early-onset AD (onset in the first 2 years of life) in Taiwan, and to determine whether the presence of allergic rhinitis (AR) or asthma affects the disease course. METHODS: The patients with early-onset AD in a nationally representative cohort were selected using the National Health Insurance Research Database of Taiwan and were followed from birth to 10 years of age. Kaplan-Meier survival analysis was carried out to analyse the disease duration and remission of AD. Between-group analysis using the log-rank test was carried out to analyse the influence of risk factors on the disease course. RESULTS: Of the 1404 children with early-onset AD, 19.4% had disease duration < 1 year and 48.7% had disease duration < 4 years. During the follow-up, 69.8% of the patients went into remission. Sex, onset age, presence of AR, presence of asthma and presence of respiratory atopy (either AR or asthma) did not show statistically significant influence on disease course. CONCLUSIONS: Children in Taiwan with early-onset AD had disease of variable natural course, and the median disease duration was 4.2 years. About 70% of the patients went into remission eventually. The presence of AR or asthma did not affect the disease course of AD.

Effects of freezing rates and cryoprotectant on thermal expansion of articular cartilage during freezing process.

The intact articular cartilage has not yet been successfully preserved at low temperature most likely due to the volume expansion from water to ice during freezing. The objective of this current study focuses on examining thermal expansion behavior of articular cartilage (AC) during freezing from 0 degree C to -100 degree C. Thermo Mechanical Analysis (TMA) was used to investigate the effects of different concentrations of dimethyl sulphoxide (DMSO) (0%, 10%, 30% and 60% v/v) and different freezing rates (1 C/min, 3 C/min and 5 C/min). The results showed that: (1) the inhomogeneous thermal expansion (or contraction) presents due to inhomogeneous water distributions in articular cartilage during freezing, which also may be the most likely reason that the matrix has been damaged in cryopreserved intact articular cartilage; (2) at the phase transition temperature range, the maximum thermal strain change value for 5C/min is approximately 1.45 times than that for 1 C/min, but the maximum thermal expansion coefficient of the later is about six times than that of the former; (3) the thermal expansion coefficient decreases with increasing cooling rate at the unfrozen temperature region, but some opposite results are obtained at the frozen temperature region; (4) the higher the DMSO concentration is, at the phase change temperature region, the smaller the thermal strain change as well as the maximum thermal expansion coefficient are, but DMSO concentration exhibits little effect on the thermal expansion coefficient at both unfrozen and frozen region. Once the DMSO concentration increasing enough, e.g. 60% v/v, the thermal strain decreases linearly and smoothly without any abrupt change due to little or no ice crystal forms (i.e. vitrification) in frozen articular cartilage. This study may improve our understanding of the thermal expansion (or contraction) behavior of cryopreserved articular cartilage and it may be useful for the future study on cryopreservation of intact articular cartilage.

Imaging cells and sub-cellular structures with ultrahigh resolution full-field X-ray microscopy.

Our experimental results demonstrate that full-field hard-X-ray microscopy is finally able to investigate the internal structure of cells in tissues. This result was made possible by three main factors: the use of a coherent (synchrotron) source of X-rays, the exploitation of contrast mechanisms based on the real part of the refractive index and the magnification provided by high-resolution Fresnel zone-plate objectives. We specifically obtained high-quality microradiographs of human and mouse cells with 29 nm Rayleigh spatial resolution and verified that tomographic reconstruction could be implemented with a final resolution level suitable for subcellular features. We also demonstrated that a phase retrieval method based on a wave propagation algorithm could yield good subcellular images starting from a series of defocused microradiographs. The concluding discussion compares cellular and subcellular hard-X-ray microradiology with other techniques and evaluates its potential impact on biomedical research.

3-D imaging and illustration of the perfusive mouse islet sympathetic innervation and its remodelling in injury.

AIMS/HYPOTHESIS: Sympathetic nerves influence islet hormone levels in the circulation. Insights into islet sympathetic innervation and its remodelling in diabetes may impact future therapeutics. However, standard immunohistochemistry and microtome-based microscopy cannot provide an integral view of the islet neurovascular complex. We prepared transparent islet specimens to investigate the spatial relationship between sympathetic nerves, blood vessels and islet cells in normal, streptozotocin-injected and non-obese diabetic mouse models. METHODS: Cardiac perfusion of fluorescent lectin was used to label pancreatic blood vessels. Tyrosine hydroxylase and nuclear staining were used to reveal islet sympathetic innervation and microstructure. Optical clearing (i.e. use of immersion solution to reduce scattering) was applied to enable 3-dimensional confocal microscopy of islets to visualise the sympathetic neurovascular complex in space. RESULTS: Unlike previously reported morphology, we observed perfusive intra-islet, perivascular sympathetic innervation, in addition to peri-islet contacts of sympathetic nerves with alpha cells and sympathetic fibres encircling the adjacent arterioles. The intra-islet axons became markedly prominent in streptozotocin-injected mice (2 weeks after injection). In non-obese diabetic mice, lymphocytic infiltration remodelled the peri-islet sympathetic axons in early insulitis. CONCLUSIONS/INTERPRETATION: We have established an imaging approach to reveal the spatial features of mouse islet sympathetic innervation. The neurovascular complex and sympathetic nerve-alpha cell contact suggest that sympathetic nerves modulate islet hormone secretion through blood vessels, in addition to acting directly on alpha cells. In islet injuries, sympathetic nerves undergo different remodelling in response to different pathophysiological cues.

Preparation, morphology and coagulation characteristics of a new polyferric chloride coagulant prepared using pyrite cinders.

Pyrite cinders are the main industrial waste generated from the process of sulphuric acid production using pyrite ores. The pyrite cinders may have utilization value in preparing a new polyferric chloride (PFC) coagulant. In order to attain this objective, a preparation method for PFC products from pyrite cinders was studied by a Taguchi orthogonal array experiment. On the basis of the successful preparation, the morphologies and coagulation characteristics of three PFC products, with different basicities, were observed by transmission electron microscopy (TEM) and examined by jar tests, respectively. The results showed that the molar ratio of NaOH to Fe should be in a range between 0.75:1 and 1:1, the molar ratio of stabilizer NaH2PO4 to Fe should be in a range between 0.12:1 and 0.15:1, the curing time should be 2 h, the curing temperature can be 60 degrees C and the molar ratio of NaHCO3 to Fe can be determined according to the basicity required in order to get the optimal stability of PFC products and the best flocculation efficiency. Although the degree of aggregation of the PFC products became larger with the increase in the basicity, the coagulation efficiency could be only improved with an increase in the basicity within a certain range. When the basicity exceeded a certain value, the coagulation efficiency started to decrease. In this study, PFC2 (B = 11.16%) had better coagulation characteristics than either PFCl (B = 6.08%), PFC2 (B = 11.16%), PFC3 (B = 15.92%) or polyaluminium chloride (PAC).