[Effect of Coconut Fiber Biochar and Its Nitrate Modification on Pb Passivation in Paddy Soils].

The effects of coconut fiber biochar (CFB) and nitrate-modified coconut fiber biochar (NCFB) on the passivation of exogenous lead (Pb) in paddy soils and their underlying mechanisms were investigated using soil incubation experiments combined with spectroscopic techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), synchrotron radiation X-ray fluorescence (SRXRF), and Fourier transform infrared absorption spectroscopy (FTIR). The effects of NCFB and CFB on the passivation of exogenous lead (Pb) in paddy soils and its underlying mechanisms were investigated. Compared with that of CFB, the inner wall of NCFB honeycomb pores was rougher, and the amount of alcohol-phenol-ether functional groups containing the C-O structure and the amount of carboxyl groups containing the C[FY=,1]O/O[FY=,1]C-O structure on the surface of CFB was significantly decreased after nitric acid modification. Compared with that in the control (without biochar) paddy soil after 150 d of incubation, the EDTA-extracted Pb content in the paddy soil with CFB and NCFB was reduced by 39.7% and 105.4%, respectively. The carbonate-bound and Fe-Mn oxide-bound Pb contents were significantly lower, and the organic-bound and residue Pb contents were significantly higher in the NCFB-added soil. The SRXRF scans showed that the exogenous Pb was enriched in the microregions of CFB particles rich in Ca and Cu elements and relatively less so in the microregions of soil aggregates rich in the Fe, Mn, and Ti elements. In addition, the characteristic peaks of carboxylates (1384 cm-1) in A-CFBPb and A-NCFBPb were significantly enhanced in the incubation experiment in the presence of exogenous Pb compared to A-CFB and A-NCFB in the absence of exogenous Pb. The addition of CFB or NCFB was more effective in passivating exogenous Pb in paddy soils and promoted the gradual transformation of Pb from unstable to more stable forms in paddy soils to achieve the effect of passivating Pb. The greater amount of carboxyl functional groups in NCFB participated in the passivation of exogenous Pb, which made NCFB more effective than CFB in passivating Pb. NCFB was more effective than CFB in passivating exogenous Pb in paddy soils due to its rougher inner walls of honeycomb pores and abundant carboxyl functional groups. In tropical areas such as Hainan, coconut fiber biochar and its modification can be considered as an environmentally friendly candidate method for the remediation of soil Pb contamination.

Efficacy and safety of salvianolate and enoxaparin in the prevention of perioperative deep venous thrombosis in gastrointestinal surgery.

OBJECTIVE: In this study, the efficacy and safety of salvianolate were compared with enoxaparin in the prevention of perioperative deep vein thrombosis in gastrointestinal surgery. METHODS: From October 2017 to September 2019, 563 patients who underwent gastrointestinal surgery were collected. Based on the inclusion and exclusion criteria, 119 patients were divided into two groups: enoxaparin group (n = 65) and salvianolate group (n = 54). Comparisons were made regarding the outcomes: prothrombin time (PT), prothrombin activity (PTA), international normalized ratio (INR), activated partial thromboplastin time (APTT), fibrinogen (FIB), thrombin time (TT), D-dimer level (D-D), platelet count (PLT), hematokrit (HCT), and incidence of deep vein thrombosis (DVT). RESULTS: The main outcomes showed no significance between enoxaparin group and salvianolate group (p > .05). The incidence of DVT in salvianolate group was 1.85%, significantly lower than that in enoxaparin group (12.3%) (p < .05). No serious adverse reactions occurred in the two groups during treatment. CONCLUSION: Compared with enoxaparin, salvianolate has an advantage in the prevention of perioperative thrombosis in gastrointestinal surgery with a lower incidence of DVT.

A far-red/near-infrared fluorescence probe with large Stokes shift for monitoring butyrylcholinesterase (BChE) in living cells and in vivo.

Accurate detection of butyrylcholinesterase (BChE) activity is imperative to understand its biological function and diagnose related disease. Far-red (FR)/Near-Infrared (NIR) fluorescent probe with large Stokes shift for BChE detection is extremely important. In this study, we reported a new "off-on" FR/NIR fluorescent probe (DX-2) with large Stokes shift (110 nm). DX-2 was constructed through cyclopropionate to pull-push the optical tuable hydroxyl group of chloro-substituted dicyanoisophorone fluorophore. DX-2 (λex/λem = 555/665 nm) featured high sensitivity (LOD∼0.08 U/mL) and selectivity, good pH practicability, low toxicity and good cell membrane permeability with a bright emission triggered by BChE. Furthermore, DX-2 exhibited good optical performance to image BChE activity in living cells. More importantly, the FR/NIR probe DX-2 was successfully applied to real-time monitor BChE in live tumor-bearing mouse model. These studies suggest that probe DX-2 has potential applicable value for detecting BChE in living biological systems and diagnosing BChE-related diseases.

Identification of novel SMN1 subtle mutations using an allelic-specific RT-PCR.

Spinal muscular atrophy (SMA) is caused by homozygous deletions of the SMN1 gene in approximately 95% of patients. The remaining 5% of patients with SMA retain at least one copy of the SMN1 gene carrying insertions, deletions, or point mutations. Although molecular genetic testing for most SMA patients is quite easy, diagnosing "nondeletion" SMA patients is still compromised by the presence of a highly homologous SMN2 gene. In this study, we analyzed the SMN1/SMN2 copy number by quantitative PCR and multiplex ligation-dependent probe amplification (MLPA). Further, common primers for both SMN1 and SMN2 sequences were used to screen DNA intragenic mutations. To confirm whether the identified mutations occurred in SMN1 or SMN2, we improved the traditional RT-PCR method by only amplifying SMN1 transcripts using an allelic-specific PCR (AS-RT-PCR) strategy. We identified six SMN1 point mutations and small indels in 8 families, which included c.683T>A, c.22dupA, c.815A>G, c.19delG, c.551_552insA and c.401_402delAG. To the best of our knowledge, the latter three have never been previously reported. The most common mutation in Chinese patients is c.22dupA, which was identified in three families. In this work, we demonstrated AS-RT-PCR to be reliable for identifying SMN1 subtle mutations, especially the prevalent mutation c.22dupA in Chinese SMA patients. By reviewing published papers and summarizing reported SMN1 mutations, a distinct ethnic specificity was found in SMA patients from China. Our research extends the SMN1 mutation spectrum.

[Evaluation of the Potential Agricultural Risks of Polycyclic Aromatic Hydrocarbon Contaminated Soil by Planting Lactuca sativa L.]

In order to evaluate the potential agricultural risks of soil contaminated by polycyclic aromatic hydrocarbons (PAHs), Lactuca sativa L. was used as a model leaf vegetable plant to investigate the enrichment characteristics of PAHs in the different tissues of Lactuca sativa L, such as its underground parts (GS) and aboveground parts (YS), which were studied through an experiment involving potted cultivation in PAHs contaminated soil that was taken from the agricultural soil around a coking enterprise area. The concentrations of the different PAHs in the soil and plant tissues were analyzed using ultrasonic oscillation extraction and high-performance liquid chromatography-mass spectrometry (GC-MS) analysis methods. The results show that the enrichment of the total PAHs (Σ16PAHs) in the YS is higher than that in the GS. The components enriched in the YS mainly consist of 3-5 ring PAHs, and those in the GS consist of 4-6ring PAHs. The coefficients of the different PAHs enriched in the YS were higher than those of the GS. The enrichment coefficient of anthracene (Ant) was the largest and that of fluoranthene (Fla) was the smallest in the YS, while the enrichment coefficient of benzene[a]pyre (Bap) was the largest and that of Fla was the smallest in the GS. The transfer coefficients of the different PAHs from the GS to the YS were greater than the rate from the initial soil (SS) to the GS; the value is less than 1 from the SS to GS. The correlations and goodness of fit were analyzed for the concentrations of PAHs in the SS, GS and YS. The Σ16PAHs in the SS showed positive correlations with the Σ16PAHs in the YS and in GS. The goodness of fit of the correlation of the PAHs in YS to those in the SS was the largest (R2=1.0), while the goodness-of-fit for the correlation between the GS and SS was lower (R2=0.71). The benzo[a]pyrene equivalent concentration values (Σ16PAHsBapeq) of YS and GS were 11.8 and 12.7 times the maximum value of Bap level allowed in food. The study indicates that contaminated farmland soil would present a high health risk when it was used to grow the plant.

Downregulation of MicroRNA-320d predicts poor overall survival and promotes the growth and invasive abilities in glioma.

Previous studies have demonstrated that miRNAs play an important role in tumor development and progression. The role of miR-320d has been studied in several cancers except for glioma. The aim of the study was to investigate the expression levels, biological function, and mechanism of miR-320d in glioma. The expression levels of miR-320d were detected in glioma tissues and cell lines (U87 and U251) by RT-qPCR. Cell proliferation, colony formation, apoptosis, cell cycle, and transwell assays were performed in glioma cell lines transfected with miR-320d mimics or controls to evaluate the effects of miR-320d in vitro. The expression levels of invasive-related proteins were determined by Western blot analysis. Results showed that the expression of miR-320d was significantly decreased in glioma tissues and cell lines. Overexpression of miR-320d could significantly suppress cell growth, migration and invasion, and induced cell apoptosis as well as cell cycle at G0/G1 arrest in U87 and U251 cell lines. Additionally, expression levels of MMP-2, MMP-9, N-cadherin, and integrin-ß1 reduced, while E-cadherin increased in miR-320d mimic group. Overall, this study is the first to demonstrate that miR-320d may serve as an independent prognostic factor, indicating that miR-320d is a biomarker for prognosis and therapy in glioma.

Two-Carrier Transport Induced Hall Anomaly and Large Tunable Magnetoresistance in Dirac Semimetal Cd3As2 Nanoplates.

Cd3As2 is a model material of Dirac semimetal with a linear dispersion relation along all three directions in the momentum space. The unique band structure of Cd3As2 is made with both Dirac and topological properties. It can be driven into a Weyl semimetal by symmetry breaking or a topological insulator by enhancing the spin-orbit coupling. Here we report the temperature and gate voltage-dependent magnetotransport properties of Cd3As2 nanoplates with Fermi level near the Dirac point. The Hall anomaly demonstrates the two-carrier transport accompanied by a transition from n-type to p-type conduction with decreasing temperature. The carrier-type transition is explained by considering the temperature-dependent spin-orbit coupling. The magnetoresistance exhibits a large nonsaturating value up to 2000% at high temperatures, which is ascribed to the electron-hole compensation in the system. Our results are valuable for understanding the experimental observations related to the two-carrier transport in Dirac/Weyl semimetals, such as Na3Bi, ZrTe5, TaAs, NbAs, and HfTe5.

CD109 attenuates TGF-ß1 signaling and enhances EGF signaling in SK-MG-1 human glioblastoma cells.

CD109 is a glycosylphosphatidylinositol-anchored cell surface protein that is frequently detected in squamous cell carcinomas. CD109 is a negative regulator of TGF-ß1 signaling in human keratinocytes, and the N-terminal fragment of CD109 secreted from cells after cleavage by the furin protease is important for modulating TGF-ß1 signaling. Previously, we found that CD109 is expressed in human glioblastoma cells; however, the role of CD109 in glioblastoma cells is not established. Here, we describe the effects of CD109 in human glioblastoma cell lines. Three glioblastoma cell lines, SK-MG-1, U251MG and MG178, were tested and CD109 overexpression attenuated TGF-ß1 signaling and enhanced EGF signaling in SK-MG-1, but not in U251MG or MG178. The N-terminal CD109 fragment in SK-MG-1 was hyperglycosylated compared with that in MG178 or U251MG. The conditioned medium of CD109-overexpressing SK-MG-1, containing the secreted N-terminal CD109, had a negative effect on TGF-ß1 signaling in wild-type SK-MG-1 and MG178, whereas it did not show any effect on EGF signaling. In addition, cell surface CD109 interacts with EGF receptor in SK-MG-1 overexpressing CD109, and exhibited enhanced cell migration and invasion. These findings suggest that CD109 attenuates TGF-ß1 signaling and enhances EGF signaling in SK-MG-1 cells and that the membrane-anchored CD109 may play major roles in the EGF signaling pathway.

Haplotype-based approach for noninvasive prenatal tests of Duchenne muscular dystrophy using cell-free fetal DNA in maternal plasma.

PURPOSE: This study demonstrates noninvasive prenatal testing (NIPT) for Duchenne muscular dystrophy (DMD) using a newly developed haplotype-based approach. METHODS: Eight families at risk for DMD were recruited for this study. Parental haplotypes were constructed using target-region sequencing data from the parents and the probands. Fetal haplotypes were constructed using a hidden Markov model through maternal plasma DNA sequencing. The presence of haplotypes linked to the maternal mutant alleles in males indicated affected fetuses. This method was further validated by comparing the inferred single-nucleotide polymorphism (SNP) genotypes to the direct sequencing results of fetal genomic DNA. Prenatal diagnosis was confirmed with amniocentesis, and those results were interpreted in a blinded fashion. RESULTS: The results showed an average accuracy of 99.98% for the total inferred maternal SNPs. With a mean depth of 30× achieved in the 10-Mb target region of each sample, the noninvasive results were consistent with those of the invasive procedure. CONCLUSION: This is the first report of NIPT for DMD and the first application of a haplotype-based approach in NIPT for X-linked diseases. With further improvements in accuracy, this haplotype-based strategy could be feasible for NIPT for DMD and even other X-linked single-gene disorders.

Dexmedetomidine improves early postoperative cognitive dysfunction in aged mice.

Postoperative cognitive dysfunction (POCD) is a frequent complication following major surgery in the elderly. However, the exact pathogenic mechanisms are still unknown. Dexmedetomidine, a selective alpha 2 adrenal receptor agonist, was revealed anesthesia and brain protective role. The present study aimed to examine whether dexmedetomdine protects against POCD induced by major surgical trauma under general anesthesia in aged mice. In the present study, cognitive function was assessed by Y-maze. Proinflammatory cytokines interleukin-1ß (IL-1ß) and tumor necrosis factor (TNF-α), apoptosis-related factor caspase-3 and Bax were detected by real-time PCR, Western blot or immunohistochemistry. The results showed that anesthesia alone caused weak cognitive dysfunction on the first day after general anesthesia. Cognitive function in mice with splenectomy under general anesthesia was significantly exacerbated at the first and third days after surgery, and was significantly improved by dexmedetomidine administration. Splenectomy increased the expression of IL-1ß, TNF-α, Bax and caspase-3 in hippocampus. These changes were significantly inversed by dexmedetomidine. These results suggest that hippocampal inflammatory response and neuronal apoptosis may contribute to POCD, and selective alpha 2 adrenal receptor excitation play a protective role.

Anti-hepatitis B virus activities and absolute configurations of sesquiterpenoid glycosides from Phyllanthus emblica.

During the process exploring anti-viral compounds from Phyllanthus species, eight new highly oxygenated bisabolane sesquiterpenoid glycoside phyllaemblicins G1­G8 (1­8) were isolated from Phyllanthus emblica, along with three known compounds, phyllaemblicin F (9), phyllaemblic acid (10) and glochicoccin D (11). Phyllaemblicin G2 (2), bearing a tricyclo [3.1.1.1] oxygen bridge ring system, is an unusual sesquiterpenoid glycoside, while phyllaemblicins G6­G8 (6­8) are dimeric sesquiterpenoid glycosides with two norbisabolane units connecting through a disaccharide. All the structures were elucidated by the extensive analysis of HRMS and NMR data. The relative configuration of phyllaemblicin G2 was constructed based on heteronuclear coupling constants measurement, and the absolute configurations for all new compounds were established by calculated electronic circular dichroism (ECD) using time dependent density functional theory. The sesquiterpenoid glycoside dimers 6­9 displayed potential anti-hepatitis B virus (HBV) activities, especially for the new compound 6 with IC50 of 8.53 ± 0.97 and 5.68 ± 1.75 µM towards the HBV surface antigen (HBsAg) and HBV excreted antigen (HBeAg) secretion, respectively.

A new sesquiterpene lactone from the fruits of Illicium henryi.

AIM: To study the chemical constituents of the fruits of Illicium henryi. METHOD: Chromatographic separations on silica gel, Sephadex LH-20 gel and MCI gel were used to isolate the compounds. The structures were elucidated based on extensive spectroscopic data analyses. RESULTS: Seven compounds were obtained and their structures were identified as 10-benzoyl-cycloparvifloralone (1), cycloparvifloralone (2), 2α-hydroxycycloparviforalone (3), henrylactone B (4), merrillianone (5), henrylactone C (6) and 7, 14-ortholactone- 3-hydroxyfloridanolide (7). CONCLUSION: Compound 1 is a new sesquiterpene lactone. The tested compounds showed weak anti-HBV activities on HBV surface antigen (HBsAg) secretion and HBV e antigen (HBeAg) secretion using Hep G2.2.15 cell line.

[A case with partial trisomy 7 (q34→qter) derived from a paternal reciprocal translocation t(7;14)(q34;q32)].

OBJECTIVE: To determine the origin of chromosomal aberrants in a mentally retarded children, and to correlate the karyotype with phenotype. METHODS: Routine G-banding were performed to analyze the karyotype of the patient and her parents, and array comparative genomic hybridization (array CGH) were used for finely mapping the aberrant regions. RESULTS: The mother had a normal karyotype. The father had an apparently balanced translocation involving chromosome 7q and 14q, the karyotype was 46, XX, t(7;14) (q34;q32), the karyotype of the child was then ascertained as 46, XX, der(14) t(7;14) (q34;q32.33) pat. Array CGH finely mapped the duplication to 7q34-qter, a 17.09 Mb region, and a very small associated deletion of distal chromosome 14 to 14q32.33-qter, a 2.27 Mb region. The patient presented some frequently seen features in partial trisomy 7q cases such as mental retardation, low birth weight, small nose, cleft palate, low-set ears and short neck. CONCLUSION: This result suggested that partial trisomy 7q exert mainly phenotypic effect on the patient. Parental karyotype analysis could help define the aberrant type.

[Relationship between miR-218 and CDK6 expression and their biological impact on glioma cell proliferation and apoptosis].

OBJECTIVES: To investigate the relationship between the expression of miR-218 and CDK6 in glioma cells, and their biological impacts on the tumor cell proliferation and apoptosis. METHODS: Expression levels of miR-218 as well as CDK6 and Ki-67 proteins were analyzed in 60 cases of gliomas with various grades and 10 control brain tissue samples by tissue microarray, locked oligonucleotide probe in situ hybridization and immunohistochemistry. Glioblastoma multiform cell line (U87MG) was transfected with miR-218 mimics (mimics group) and a control sequence (control group), followed by qRT-PCR detection of miR-218 and immunocytochemical stain of CDK6 and Ki-67, respectively. Single cell gel electrophoresis was used to detect the presence of apoptotic cell. RESULTS: The miR-218 labeling indexes (LI) were statistically different (P<0.05) among all groups including control (22.45 +/- 0.59) and various glioma groups (grades I - II 4.00 +/- 1.07, grade III 1.87 +/- 1.06 and grade IV 0.94 +/- 0.78, respectively). The CDK6 LI of the four groups was 7.25 +/- 1.20, 16.71 +/- 0.80, 24.43 +/- 0.62 and 32.05 +/- 0.43, respectively. Significant differences existed between the control group and the glioma groups, and between grade IV and grades I - II glioma groups (P<0.01). Ki-67 positive cell densities of the above four groups (0.00 +/- 0.00, 9.30 +/- 3.48, 31.15 +/- 9.44 and 60.15 +/- 13.60) were significantly different from one and another (P<0.01). The expression of miR-218 negatively correlated with CDK-6 LI (r = -0.480, P<0. 01) and Ki-67 positive cell density (r = - 0.534, P<0.01), while the latter two positively correlated with each other (r = 0.530, P<0.01). U87MG transfection experiment showed that the miR-218 level of the mimics group was significantly higher than that of the control group (P<0.01). CDK6 and Ki-67 LI of the mimics group (14.74 +/- 1.19 and 30.88 +/- 3.31) were significantly lower than those of the control group (79.06 +/- 2.07 and 64.94 +/- 3.96, P<0.01), whilst its apoptotic index (AI) (68.44 +/- 7.05) was significantly higher than that of the control group (13.04 +/- 0.97, P<0.01). CONCLUSIONS: The expression level of miR-218 is an important reference indicator for the assessment of the grade of gliomas. An aberrant decrease of its expression may lead to an increase of the CDK6 expression and proliferative activity of giloma cells. Introducing exogenous miR-218 may effectively down-regulate the CDK6 expression, inhibit cell proliferation and induce apoptosis of malignant giloma cells. These findings imply that miR-218 may serve as a therapeutic agent against malignant glioma.

[Two cases of partial trisomy 8p derived from paternal reciprocal translocation or maternal insertion translocation: clinical features and genetic abnormalities].

OBJECTIVE: To determine the origin of aberrant chromosomes involving the short arm of chromosome 8 in two mentally retarded children, and to correlate the karyotype with abnormal phenotype. METHODS: Routine G-banding was performed to analyze the karyotypes of the two patients and their parents, and array comparative genomic hybridization (array CGH) was used for the first patient for fine mapping of the aberrant region. RESULTS: The first patient presented with only mental retardation. The father had normal karyotype. The mother had an apparent insertion translocation involving chromosomes 8 and 3 [46, XX, inv ins (3; 8) (q25.3; p23.1p11.2)], the karyotype of the child was ascertained as 46, XX, der(3) inv ins (3; 8)(q25.3; p23.1p11.2). Array CGH finely mapped the duplication to 8p11.21-8p22, a 26.9 Mb region. The other patient presented with mental retardation, craniofacial defects, congenital heart disease and minor skeletal abnormality. The mother had normal karyotype. The father had an apparently balanced translocation involving chromosome 8p and 11q, the karyotype was 46, XY, t(8; 11)(p11.2; q25). The karyotype of the child was then ascertained as 46, XX, der(11)t(8; 11)(p11.2; q25). CONCLUSION: These results suggested that partial trisomy 8p was primary cause for the phenotypic abnormalities of the two patients, whereas a mild phenotypic effect was observed in patient 1. Parental karyotype analysis could help define the aberrant type and recurrent risk evaluation. In contract to routine karyotype analysis, aberrant regions could be mapped by array CGH with higher resolution and accuracy.

[Cytogenetic and molecular genetic study of a case with 8p inverted duplication deletion syndrome].

OBJECTIVE: To define the origin and the precise location of the aberrant fragments on the short arm of the chromosome 8 in a mentally retarded boy, and to understand the mechanism, the characteristic clinical features and the recurrent risk associated with this abnormality. METHODS: High-resolution chromosomal banding was performed to analyze the karyotype of the patient and his parents, array comparative genomic hybridization (array-CGH) was employed to investigate the precise location of the aberrant fragments, and quantitative real-time PCR was used to confirm the results. RESULTS: The rearranged chromosome 8 in the patient was inverted and duplicated for region 8p11.2-p23.1, and deleted for region 8p23.1-pter. In between, a 5.70 Mb single copy region was present, which was delimited by the two olfactory receptor (OR) gene clusters. CONCLUSION: This is a case of classic inv dup del(8p) syndrome, which is characterized by severe mental retardation, brain malformation and specific facial dysmorphism, and is induced by non-allelic homologous recombination (NAHR) between the OR genes on 8p23.1. Prenatal diagnosis should be performed to monitor the recurrent risk of inv dup del(8p), as well as the other three harmful consequences resulted from the same NAHR mechanism. To the best of our knowledge, this is the first case of inverted duplicated 8p syndrome identified in Mainland China.

Elevation of PTH and PTHrp induced by excessive fluoride in rats on a calcium-deficient diet.

Study on the role of parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrp) in the process of skeletal fluorosis, involved especially in calcium deficiency, is rare. We evaluated the level of serum PTH and mRNA expression of PTHrp in femur when rats were exposed to excessive fluoride with low-calcium diet. Wistar rats (n = 60) was divided into four groups, a control group, fluoride group, low-calcium group, and low-calcium fluoride group. The fluoride groups were treated with fluoride by drinking tap water containing 100 mg F-/L. The low-calcium diet contained 0.05% calcium. Serum was collected in the first, fourth, eighth, and 12th of phase for the detemination of PTH and Ca(2+). RNA extraction from femora was used to analyze the mRNA express of PTHrp, osteopontin (OPN), and osteocalcin (OCN) after 12 weeks of fluoride dosing. Results showed that serum PTH increased gradually with the extension of fluoride exposure, but Ca2+ decreased, both of which embodied a time-dependent relationship. Cotreatment of excessive fluoride with low-calcium diet largely stimulated the secretion of PTH. The low dietary calcium markedly increased mRNA expression of PTHrp in animals with fluoride treatment. Expression of OPN and OCN significantly increased in the rats treated with excessive fluoride and low-calcium diet. We demonstrated that fluoride by itself affected the body's calcium metabolism and stimulate the secretion of PTH. PTH may play an important role in anabolic effect of excessive fluoride on bone turnover of skeletal fluorosis and calcium deficiency exacerbated the action of PTH and PTHrp on the characteristic bone lesion of fluorosis.

Influence of temperature and illumination on surface barrier of individual ZnO nanowires.

The current-voltage (I-V) characteristics of single ZnO nanowires were measured varying with temperature and illumination. A model of the ZnO nanowire sandwiched by back-to-back diodes was utilized to explain the experimental data. Simulations of the I-V curves exhibited that the surface barrier height was independent of temperature from 180 to 290 K. This work also shows that the larger the incident laser power is, the smaller the contact surface barrier height will be. The photon induced reduction in the surface barrier height is attributed to the photogenerated holes, which result in a shielding effect on the surface trapped electrons.

The effect of adsorbates on the space-charge-limited current in single ZnO nanowires.

We studied the influence of adsorbates on the space-charge-limited current (SCLC) in individual ZnO nanowires through varying the bias voltage, laser illumination, and ambient pressure. In dark and air conditions, the free carriers were depleted by the surface adsorbates, and electrons injected from the electrode to the nanowire dominated the electron transport properties. Under laser illumination, the current-voltage characteristic was linear at low voltage and superlinear at high voltage, and the SCLC regime occurred at high voltages due to the surface desorption. The time response of photoconductivity further revealed the dynamic process of elimination of SCLC by desorption of oxygen molecules at the ZnO nanowire surface.