Experimental Limits on Exotic Spin and Velocity Dependent Interactions Using Rotationally Modulated Source Masses and an Atomic-Magnetometer Array.

Various theories beyond the standard model predict new interactions mediated by new light particles with very weak couplings to ordinary matter. Interactions between polarized electrons and unpolarized nucleons proportional to g_{V}^{N}g_{A}^{e}σ[over →]·v[over →] and g_{A}^{N}g_{A}^{e}σ[over →]·v[over →]×r[over →] are two such examples, where σ[over →] is the spin of the electrons, r[over →] and v[over →] are position and relative velocity between the polarized electrons and nucleons, g_{V}^{N}/g_{A}^{N} is the vector or axial-vector coupling constant of the nucleon, and g_{A}^{e} is the axial-vector coupling constant of the electron. Such interactions involving a vector or axial-vector coupling g_{V}^{N}/g_{A}^{N} at one vertex and an axial-vector coupling g_{A}^{e} at the polarized electron vertex can be induced by the exchange of spin-1 bosons. We report new experimental upper limits on such exotic spin-velocity-dependent interactions of the electron with nucleons from dedicated experiments based on a recently proposed scheme. We rotationally modulated two ∼6 Kg source masses at a frequency of 20 Hz. We used four identical atomic magnetometers in an array form to increase the statistics and cancel the common-mode noise. We applied a data processing method based on high precision numerical integration for the four harmonic frequencies of the signal. We reverse the rotation direction of the source masses to flip the signal due to the new interactions; thus, we can apply the [+1,-3,+3,-1] weighting method to remove possible slow drifting. Our constraint on the product of vector and axial-vector couplings is |g_{V}^{N}g_{A}^{e}|<2.1×10^{-34} and on the product of axial-vector and axial-vector couplings is |g_{A}^{N}g_{A}^{e}|<2.4×10^{-22} for an interaction range of 10 m. The new constraints on vector-axial-vector interaction improved by as much as more than 4 orders of magnitude and on axial-axial interaction by as much as 2 orders of magnitude in the corresponding interaction range, respectively.

Searching for New Spin- and Velocity-Dependent Interactions by Spin Relaxation of Polarized

We have constrained possible new interactions which produce nonrelativistic potentials between polarized neutrons and unpolarized matter proportional to ασ[over →]·v[over →] where σ[over →] is the neutron spin and v[over →] is the relative velocity. We use existing data from laboratory measurements on the very long T_{1} and T_{2} spin relaxation times of polarized ^{3}He gas in glass cells. Using the best available measured T_{2} of polarized ^{3}He gas atoms as the polarized source and the Earth as an unpolarized source, we obtain constraints on two new interactions. We present a new experimental upper bound on possible vector-axial-vector (V_{VA}) type interactions for ranges between 1 and 10^{8} m. In combination with previous results, we set the most stringent experiment limits on g_{V}g_{A} ranging from ~µm to ~10^{8} m. We also report what is to our knowledge the first experimental upper limit on the possible torsion fields induced by the Earth on its surface. Dedicated experiments could further improve these bounds by a factor of ~100. Our method of analysis also makes it possible to probe many velocity dependent interactions which depend on the spins of both neutrons and other particles which have never been searched for before experimentally.

Association between dental caries and adiposity status (general, central, and peripheral adiposity) in 12-year-old children.

BACKGROUND/AIMS: To investigate the cross-sectional relationship between dental caries experience and adiposity status (general, central, and peripheral adiposity) in 12-year-old children in Hong Kong. METHODS: A random sample of 668 12-year-old students was recruited. Clinical assessment for dental caries (DMFT) was conducted using WHO criteria. Anthropometric measurements for body height, body weight, waist circumference (WC), hip circumference and triceps skinfold thickness (TRSKF) were performed to assess general adiposity (weight-height ratio, body mass index); central adiposity (WC; waist-hip ratio, WHR), and peripheral adiposity (TRSKF). Associations between adiposity indices and dental caries experience [prevalence DMFT > 0, 'high' experience (DMFT ≥ SiC Index value) and 'very high' experience (DMFT ≥ SiC10 Index value)] were examined in bivariate and multivariate regression analyses. RESULTS: The response rate was 76.9% (n = 514/668). Regression analyses (adjusted for oral hygiene practice, snacking habits, and socio-demographic factors) identified that WHR z score was associated with 'high' dental caries experience (OR 1.33, 95% CI 1.05, 1.70, p = 0.02), and that WHR z score was associated with 'very high' dental caries experience (OR 1.52, 95% CI 1.10, 2.11, p = 0.01). TRSKF z score was associated with 'very high' dental caries experience (OR 1.47, 95% CI 1.10, 1.96, p = 0.01). CONCLUSIONS: In a population-based sample of 12-year-old children in Hong Kong, dental caries experience was associated with adiposity. Central and peripheral, but not general adiposity was associated with dental caries experience.

The relationship between oral hygiene status and obesity among preschool children in Hong Kong.

OBJECTIVES: To explore the association between oral hygiene status and obesity among preschool children in Hong Kong. METHODS: Three hundred and twenty-four 5-year-old children in Hong Kong were recruited. Their oral hygiene status was recorded using visible plaque index (VPI). Body height, body weight, waist circumference (WC), hip circumference and triceps skinfold thickness (TRSKF) were measured to assess general adiposity (weight/height ratio, W/H; body mass index, BMI), central adiposity (WC; waist/hip ratio, WHR) and peripheral adiposity (TRSKF). The relationships between VPI and W/H, BMI, WC, WHR and TRSKF were examined in bivariate and regression analyses. RESULTS: Fifty-six per cent of the children were considered to have high VPI (VPI ≥ 65.0%). Logistic regression analyses identified that W/H z-score (OR = 1.28, 95% CI = 1.01-1.61) and WC z-score (OR = 1.25, 95% CI = 1.00-1.58) were associated with high VPI. No association was found after adjusted for socio-demographic status (P > 0.05). CONCLUSION: Oral hygiene status was not associated with obesity among 5-year-old children in Hong Kong after controlling for socio-demographic factors.

[Application of exosomes in oral regenerative medicine].

In recent years, exosomes had been recognized as a potential cell-free therapeutic tool in the field of regenerative medicine due to their easy accessibility, low immunogenicity, and good therapeutic effect. As paracrine products of cells, exosomes not only have the functions of their donor cells but also involve fewer ethical disputes. They are more stable than traditional stem cell therapy, and easy to store, transport and sterilize, which are gradually applied in the field of oral regenerative medicine. This article provides a review of the general properties of exosomes and their application in the field of oral regeneration, with a view to exploring new pathways for functional regeneration of the stomatognathic system.

Ab initio study of stability and migration of H and He in hcp-Sc.

Ab initio calculations based on density functional theory have been performed to determine the relative stabilities and migration of H and He atoms in hcp-Sc. The results show that the formation energy of an interstitial H or He atom is smaller than that of a corresponding substitutional atom. The tetrahedral (T) interstitial position is more stable than an octahedral (O) position for both He and H interstitials. The nudged elastic band method has been used to study the migration of interstitial H and He atoms in hcp-Sc. It is found that the migration energy barriers for H interstitials in hcp-Sc are significantly different from those for He interstitials, but their migration mechanisms are similar. In addition, the formation energies of five different configurations of a H-H pair were determined, revealing that the most stable configuration consists of two H atoms located at the second-neighbor tetrahedral interstitial sites along the hexagonal direction. The formation and relative stabilities of some small He clusters have also been investigated.

Ultraviolet ZnO nanorod photosensors.

This study fabricates and characterizes ultraviolet (UV) photosensors with ZnO nanorods (NRs). The NR arrays were selectively grown in the gap between interdigitated (IDT) electrodes of devices using hydrothermal solution processes and a lithography-based technique. Compared with a conventional ZnO photosensor without NRs, the proposed UV NR photosensors have much higher photoresponse in the UV region. Additionally, the photoconductive gain of an NR photosensor increased as UV illumination time increased; it varied at 34.45-5.32 x 10(2) under illumination by 18.28 mW/cm(2) optical power. Consequently, the substantial photoconductive gain can be attributed to high surface-to-volume ratio of ZnO NRs. The high density of hole-trap states on NR surfaces lead to a persistent photoconductivity (PPC) state, promoting the transport of carriers through devices.

Effects of stacking periodicity on the electronic and optical properties of GaAs/AlAs superlattice: a first-principles study.

The effects of stacking periodicity on the electronic and optical properties of GaAs/AlAs superlattice have been explored by density functional theory calculations. Among the (GaAs)m/(AlAs)m, (GaAs)1/(AlAs)m and (GaAs)m/(AlAs)1 (m = 1 to 5) superlattices, the band gaps of (GaAs)m/(AlAs)1 superlattices decrease significantly as the layer of GaAs increases, and the cut-off wavelengths are found to locate in the near infrared region. For (GaAs)m/(AlAs)1 SLs, the conduction bands shift toward Fermi level, resulting in the smaller band gap, while conduction bands of (GaAs)1/(AlAs)n SLs slightly shift to higher energy, which lead to comparable band gaps. The layer number of GaAs shows negligible effects on the reflectivity spectra of superlattice structures, while the absorption coefficient shows a red-shift with the increasing layer of GaAs, which is beneficial for the application of GaAs/AlAs superlattice in the field of near infrared detector. These results demonstrate that controlling the number of GaAs layers is a good method to engineer the optoelectronic properties of GaAs/AlAs superlattice.

A comparative study of low energy radiation response of AlAs, GaAs and GaAs/AlAs superlattice and the damage effects on their electronic structures.

In this study, the low energy radiation responses of AlAs, GaAs and GaAs/AlAs superlattice are simulated and the radiation damage effects on their electronic structures are investigated. It is found that the threshold displacement energies for AlAs are generally larger than those for GaAs, i.e., the atoms in AlAs are more difficult to be displaced than those in GaAs under radiation environment. As for GaAs/AlAs superlattice, the Ga and Al atoms are more susceptible to the radiation than those in the bulk AlAs and GaAs, whereas the As atoms need comparable or much larger energies to be displaced than those in the bulk states. The created defects are generally Frenkel pairs, and a few antisite defects are also created in the superlattice structure. The created defects are found to have profound effects on the electronic properties of GaAs/AlAs superlattice, in which charge transfer, redistribution and even accumulation take place, and band gap narrowing and even metallicity are induced in some cases. This study shows that it is necessary to enhance the radiation tolerance of GaAs/AlAs superlattice to improve their performance under irradiation.

Boron carbide composites with highly aligned graphene nanoplatelets: light-weight and efficient electromagnetic interference shielding materials at high temperatures.

B4C-based ceramic composites containing 0-2 vol% highly aligned graphene nanoplatelets (GNPs) are fabricated. The electromagnetic interference (EMI) shielding properties of the obtained composites are investigated at X-band (8.2-12.4 GHz) frequency range from room-temperature up to 800 °C. All composites exhibit outstanding EMI shielding properties with satisfactory frequency- and thermal-stability. The shielding effectiveness (SE) of GNP/B4C composites increases monotonically with increasing GNP loading. Superior room-temperature SE close to 40 dB is achieved with only 2 vol% GNPs and high SE around 35 dB still persists at 800 °C. Considering their relatively low density, GNP/B4C composites possess a high specific shielding effectiveness (SSE) of 16 dB cm3 g-1 which is among the highest values in reported ceramic-based shielding composites. Especially, the GNP/B4C composite with 2 vol% GNPs exhibits the highest SSE/t (SSE divided by thickness) values at temperatures above 200 °C for all reported shielding composites, indicating that GNP/B4C composites belong to the most promising high-temperature shielding composites. The excellent shielding properties of GNP/B4C composites arise mainly from the high electrical conductivity, high dielectric loss and the multiple reflections by the highly aligned and large-sized GNP layers.

A novel HLA-G allele, HLA-G*01:01:01:07, was identified in a Chinese patient with Posner-Schlossman syndrome.

A novel HLA-G allele, HLA-G*01:01:01:07, was identified in a Chinese patient with Posner-Schlossman syndrome.

USP22 down-regulation facilitates human retinoblastoma cell aging and apoptosis via inhibiting TERT/P53 pathway.

OBJECTIVE: Retinoblastoma is the most common malignant intraocular tumor in childhood, and still lacks effective treatment. The immortality of tumor cell can be attributed to elevated telomerase activity, which has been considered as tumor marker and treatment target. USP22 is one of the important targets for inhibiting tumor growth, but clear illustration regarding its effects of telomerase, tumor cell immortality and retinoblastoma cell aging or apoptosis via suppressing TERT/P53 signal pathway remains to be elusive. MATERIALS AND METHODS: MTT was used for describing cell proliferation, and Western blot was used to test protein expression level of USP22, TERT and P53. RT-qPCR was used to test USP22 mRNA level, followed by TRAP method to detect telomerase activity. Flow cytometry and comet assay were used to quantify cell apoptosis and DNA damage. Cell aging was measured by ß-galactosidase. RESULTS: The overexpression of USP22 significantly enhanced cell proliferation potency and telomerase activity, elevated TERT expression level, inhibited p53 expression and cell aging, as well as decreased cell apoptosis or DNA damage. Down-regulation of USP22 contributed to opposite effects. CONCLUSIONS: USP22 played an important role in retinoblastoma cell proliferation/aging and apoptosis. The reduction of USP22 expression facilitated human retinoblastoma cell aging or apoptosis via suppressing TERT/P53 signal pathway. USP22, thus, may work as a target for treating retinoblastoma.

Ab initio molecular dynamics simulation of the effects of stacking faults on the radiation response of 3C-SiC.

In this study, an ab initio molecular dynamics method is employed to investigate how the existence of stacking faults (SFs) influences the response of SiC to low energy irradiation. It reveals that the C and Si atoms around the SFs are generally more difficult to be displaced than those in unfaulted SiC, and the corresponding threshold displacement energies for them are generally larger, indicative of enhanced radiation tolerance caused by the introduction of SFs, which agrees well with the recent experiment. As compared with the unfaulted state, more localized point defects are generated in faulted SiC. Also, the efficiency of damage production for Si recoils is generally higher than that of C recoils. The calculated potential energy increases for defect generation in SiC with intrinsic and extrinsic SFs are found to be higher than those in unfaulted SiC, due to the stronger screen-Coulomb interaction between the PKA and its neighbors. The presented results provide a fundamental insight into the underlying mechanism of displacement events in faulted SiC and will help to advance the understanding of the radiation response of SiC with and without SFs.

Development of interesting step-climbing styles.

OBJECTIVES: This study was to investigate the influence of stepping styles (forward, side, and cross steppings) and inclinations (25 and 45 degrees) on cardiorespiratory responses (C-R responses). METHODS: Twenty volunteers were recruited and randomly arranged into two ten-people groups, exercising on step-climbing machines respectively of 25 and 45 degrees of inclination. C-R responses were recorded during each test which lasted for six minutes at 50 steps per minute on a step-climbing machine. RESULTS: The group on 25-degree inclination had significantly lower C-R responses than the group on 45-degree inclination. Although only small differences, probably statistically insignificant, were found among the three step-climbing styles, these differences showed interesting trends independent of inclination. CONCLUSIONS: Climbing stairs with the three interesting step-climbing styles in this study could be considered as an exercise of moderate intensity (60-80% HRmax ). Climbing on 25-degree inclination at 50 steps per minute is recommended for less fit individuals because of lower cardiovascular stress as compared with on 45-degree inclination.

[High-dose monotherapy in intractable epilepsy].

39 adult patients with intractable epilepsy were successfully treated with high-dose monotherapy, using carbamazepine or phenytoin. In 27 patients seizures decreased 45% and in 19 of them decreased over 50% in 6 to 24 months of follow-up. The effect of reducing polytherapy to monotherapy was studied in 20 patients. In 19 of them this was possible without an increase in seizure frequency. In 10 cases seizure decreased over 50%. Individual dosage adjustment is preferably based on clinical judgment rather than on published therapeutic ranges. The causes of intractable epilepsy, individual dosage adjustment and seizure classification were discussed.

Sputtered ZnO film on aluminium foils for flexible ultrasonic transducers.

Nanocrystalline ZnO films with both C-axis vertical grown and inclined angled grown were sputter-deposited onto aluminium foils (50 µm thick) and characterised for using as flexible ultrasonic transducers. As-deposited C-axis grown ZnO films were annealed at different temperatures up to 600 °C to enhance film crystallinity and reduce film stress. The C-axis grown ZnO film on the Al foil were bonded onto steel plates, and the pulse-echo tests verified a good performance (with dominant longitudinal waves) of the ultrasonic transducers made from both as-deposited and post-annealed films. Inclined angled ZnO films on the Al foil glued onto steel plates generated mixed shear and longitudinal waves in the pulse-echo test.

Unusual coordination mode of thiosemicarbazone ligands. A search for the origin.

Twelve mixed-ligand thiosemicarbazone complexes of ruthenium and osmium, ten of general formula [M(bpy)2(bztsc-R)]ClO4, (M = Ru, Os; bpy = 2,2'-bipyridine, Hbztsc-R = benzaldehyde thiosemicacbazone) and two of type [M(bpy)2(actsc)]ClO4 (Hactsc = acetonethiosemicarbazone), have been synthesized and characterized. All the complexes are diamagnetic (low-spin d6, S = 0) and in acetonitrile solution show several intense metal-to-ligand charge-transfer (MLCT) transitions in the visible region. Structures of Hbztsc-OMe, [Ru(bpy)2(bztsc-NO2)]ClO4 and [Ru(bpy)2(actsc)]ClO4 have been determined by X-ray crystallography. Benzaldehyde thiosemicarbazone exists in the thione form with the phenyl group trans to the hydrazinic nitrogen. The benzaldehyde thiosemicarbazone ligand coordinates to the metals through the hydrazinic nitrogen and sulfur with a bite angle of approximately 67 degrees, forming a four-membered chelate ring. However, the actsc ligand coordinates through the imine nitrogen and sulfur, forming a five-membered chelate ring with a bite angle of approximately 81 degrees. The difference in coordination modes of two types of thiosemicarbazone ligands, viz., bztsc-R and actsc, appears to result from the difference in steric bulk of the aryl and methyl group trans to the hydrazinic nitrogen. In acetronitrile solution they all show a reversible metal(II)-metal(III) oxidation in the range 0.18-0.58 V vs SCE followed by an irreversible oxidation in the range 1.11-1.60 V vs SCE. Two successive one-electron reductions of the coordinated bipyridine are also observed in the range -1.53 to -1.96 V vs SCE.

Molecular recognition with C-clamp porphyrins: synthesis, structural, and complexation studies.

Porphyrin-based molecular clefts equipped with a strategically positioned carboxylic group have been synthesized. These ditopic porphyrins exhibit excellent binding affinity for many neutral substrates. X-ray structures of a porphyrin-water inclusion complex and a Zn(porphyrin)-methanol complex reveal how the carboxylic group interacts with substrates via H-bonding. Multipoint recognition is demonstrated in the differential binding of 1,2,3- versus 1,2,4-triazole, suggesting the possible use of such receptors to separate heterocyclic bases.

Chemical control on the coordination mode of benzaldehyde semicarbazone ligands. synthesis, structure, and redox properties of ruthenium complexes.

Reaction of benzaldehyde semicarbazone (HL-R, where H is a dissociable proton and R is a substituent (R = OMe, Me, H, Cl, NO(2)) at the para position of the phenyl ring) with [Ru(PPh(3))(3)Cl(2)] and [Ru(PPh(3))(2)(CO2)Cl2] has afforded complexes of different types. When HL-NO(2) and [Ru(PPh(3))(3)Cl2] react in solution at ambient temperature, trans-[Ru(PPh(3))(2)(L-NO2Cl] is obtained. Its structure determination by X-ray crystallography shows that L-NO2 is coordinated as a tridentate C,N,O-donor ligand. When reaction between HL-NO2 and [Ru(PPh(3))(3)Cl2] is carried out in refluxing ethanol, a more stable cis isomer of [Ru(PPh(3))(2)(L-NO2)Cl] is obtained. The trans isomer can be converted to the cis isomer simply by providing appropriate thermal energy. Slow reaction of HL-R with [Ru(PPh(3))(2)(CO2)Cl2] in solution at ambient temperature yields 5-[Ru(PPh(3))(2)(L-R)(CO)Cl] complexes. A structure determination of 5-[Ru(PPh(3))(2)(L-NO2)(CO)Cl] shows that the semicarbazone ligand is coordinated as a bidentate N,O-donor, forming a five-membered chelate ring. When reaction between HL-R and [Ru(PPh(3))(2)(CO2Cl2] is carried out in refluxing ethanol, the 4-[Ru(PPh(3))(2)(L-R)(CO)Cl] complexes are obtained. A structure determination of 4-[Ru(PPh(3))(2)(L-NO2)(CO)Cl] shows that a semicarbazone ligand is bound to ruthenium as a bidentate N,O-donor, forming a four-membered chelate ring. All the complexes are diamagnetic (low-spin d(6), S = 0). The trans- and cis-[Ru(PPh(3))(2)(L-NO2)Cl] complexes undergo chemical transformation in solution. The 5- and 4-[Ru(PPh(3))(2)(L-R)(CO)Cl] complexes show sharp NMR signals and intense MLCT transitions in the visible region. Cyclic voltammetry of the 5-[Ru(PPh(3))(2)(L-R)(CO)Cl] and 4-[Ru(PPh(3))(2)(L-R)(CO)Cl] complexes show the Ru(II)-Ru(III) oxidation to be within 0.66-1.07 V. This oxidation potential is found to linearly correlate with the Hammett constant of the substituent R.

Luminescent mononuclear and binuclear cyclometalated palladium(II) complexes of 6-phenyl-2,2 bipyridines: spectroscopic and structural comparisons with platinum(II) analogues.

The mononuclear cyclometalated Pd(II) complexes [Pd(L1)X] (HL1 = 6-phenyl-2,2'-bipyridine; X = Cl, la; Br, 1b; I, 1c), [Pd(L1)PPh3]+ (1d), [Pd(L2-5)Cl] [2a-5a, HL2-5 = 4-(aryl)-6-phenyl-2,2'-bipyridine; aryl = phenyl (2), 4-chlorophenyl (3), 4-tolyl (4), 4-methoxyphenyl (5)] and the binuclear derivatives [Pd2(L1-5)2(mu-dppm)]2+ (1e-5e, dppm = bis(diphenylphosphino)methane) and [Pd2(L1)2(mu-dppCs)]2+, (1f, dppC5 = 1,5-bis(diphenylphosphino)pentane) were prepared. The crystal structures of 1d(ClO4), 1e(ClO4)2 x DMF, and 2e(ClO4)2 have been determined by X-ray crystallography. The magnitude of the Pd-Pd distances in le and 2e (3.230(1) and 3.320(2) A, respectively) suggest minimal metal-metal interaction, although pi-stacking of the aromatic ligands (interplanar separations 3.34 and 3.35 A, respectively) is evident. All complexes display low-energy UV absorptions at lambda approximately 390 nm, which are tentatively assigned to 1MLCT transitions; red shifts resulting from Pd-Pd interactions in the binuclear species are not apparent. The complexes in this work are non-emissive at 298 K, but the cationic derivatives exhibit intense luminescence at 77 K. The structured emissions of 1d and 1f in MeOH/EtOH glass (lambdamax 467-586 nm) and all cationic species in the solid state (lambdamax 493-578 nm) are assigned to intraligand excited states. Complexes le-5e display dual emissions in MeOH/EtOH glass at 77 K, and the broad structureless bands at lambdamax 626-658 nm are attributed to pi-pi excimeric IL transitions. A comparison between the photophysical properties of Pd(II) and Pt(II) congeners is presented.