Single-crystal growth, structure and thermal transport properties of the metallic antiferromagnet Zintl-phase ß-EuIn2As2.

Zintl-phase materials have attracted significant research interest owing to the interplay of magnetism and strong spin-orbit coupling, providing a prominent material platform for axion electrodynamics. Here, we report the single-crystal growth, structure, magnetic and electrical/thermal transport properties of the antiferromagnet layer Zintl-phase compound ß-EuIn2As2. Importantly, the new layered structure of ß-EuIn2As2, in rhombohedral (R3̄m) symmetry, contains triangular layers of Eu2+ ions. The in-plane resistivity ρ(H, T) measurements reveal metal behavior with an antiferromagnetic (AFM) transition (TN ∼ 23.5 K), which is consistent with the heat capacity Cp(H, T) and magnetic susceptibility χ(H, T) measurements. Negative MR was observed in the temperature range from 2 K to 20 K with a maximum MR ratio of 0.06. Unique 4f7J = S = 7/2 Eu2+ spins were supposed magnetically order along the c-axis. The Seebeck coefficient shows a maximum thermopower |Smax| of about 40 µV K-1. The kink around 23 K in the Seebeck coefficient originates from the effect of the antiferromagnetic phase on the electron band structure, while the pronounced thermal conductivity peak at around 10 K is attributed to the phonon-phonon Umklapp scattering. The results suggest that the Eu2+ spin arrangement plays an important role in the magnetic, electrical, and thermal transport properties in ß-EuIn2As2, which might be helpful for future potential technical applications.

[Induction of hepatocellular carcinoma in B6C3 (F1) mice chronicly exposed to trichloroethylene with enhanced acetylation of histone H2AK9ac and SET expression in the liver tissue].

Objective: To establish an animal model of trichloroethylene (TCE) -induced liver cancer following chronic exposure and to understand the changes in SET expression and histone acetylation, potentially serving as a molecular mechanism for TCE-induced hepatocarcinogenesis. Methods: B6C3 mice at 6 weeks were treated with TCE at a series of doses (500, 1000 and 2000 mg/kg) by gastric gavage, with corn oil used as the negative control and carbon tetrachloride (CCl(4)) as the positive control. The serum and liver were sampled for the determination of biochemical indexes and pathological examination after 56 weeks of chemical exposure. Western blot was used to determine the levels of SET, H2AK9ac and HDAC1 expression. Results: The overall survival rate of the mice in various groups was 90.4% (141/156) , with no statistical difference between groups (P>0.05) . Compared with the negative control, the organ coefficient for the liver in the high dose TCE group and the positive control group were significantly increased (P<0.05) . The levels of ALT, AST, LDH and BUN in the all the three TCE groups and the positive control were significantly higher than those in the negative control (P<0.01) . CREA levels in the 1000 and 2000 mg/kg TCE groups were significantly higher than those in the negative control (P<0.05) . Statistical increases in the incidence of hepatocellular carcinoma and the activities of ALT and AST in various doses of TCE-exposed mice as compared with the control were observed (P<0.01) , in a dose-dependent manner. In the 1000 and 2000 mg/kg of TCE treated mice, levels of SET and H2AK9ac were increased (P<0.05) , while HDAC1 was decreased (P<0.05) , Compared to the tissue adjacent to liver cancer, in the 1000 and 2000 mg/kg TCE groups, the levels of SET were increased (P<0.05) , while HDAC1 was decreased (P<0.05) , and H2AK9ac increased in the 2000 mg/kg group. Conclusion: The hepatocellular carcinoma mouse model induced by chronic exposure to trichloroethylene was successfully established, with enhanced SET protein expression and H2AK9ac in the hepatic tissue.

Thickness uniformity measurements and damage threshold tests of large-area GaAs/AlGaAs crystalline coatings for precision interferometry.

Precision interferometry is the leading method for extremely sensitive measurements in gravitational wave astronomy. Thermal noise of dielectric coatings poses a limitation to the sensitivity of these interferometers. To decrease coating thermal noise, new crystalline GaAs/AlGaAs multilayer mirrors have been developed. To date, the surface figure and thickness uniformity of these alternative low-loss coatings has not been investigated. Surface figure errors, for example, cause small angle scattering and thereby limit the sensitivity of an interferometer. Here we measure the surface figure of highly reflective, substrate-transferred, crystalline GaAs/AlGaAs coatings with a custom scanning reflectance system. We exploit the fact that the reflectivity varies with the thickness of the coating. To increase penetration into the coating, we used a 1550 nm laser on a highly reflective coating designed for a center wavelength of 1064 nm. The RMS thickness variation of a two inch optic was measured to be 0.41 ± 0.05 nm. This result is within 10% of the thickness uniformity, of 0.37 nm RMS, achieved with ion-beam sputtered coatings for the aLIGO detector. We additionally measured a lower limit of the laser induced damage threshold of 64 MW/cm 2 for GaAs/AlGaAs coatings at a wavelength of 1064 nm.

Compensated Semimetal LaSb with Unsaturated Magnetoresistance.

By combining angle-resolved photoemission spectroscopy and quantum oscillation measurements, we performed a comprehensive investigation on the electronic structure of LaSb, which exhibits near-quadratic extremely large magnetoresistance (XMR) without any sign of saturation at magnetic fields as high as 40 T. We clearly resolve one spherical and one intersecting-ellipsoidal hole Fermi surfaces (FSs) at the Brillouin zone (BZ) center Γ and one ellipsoidal electron FS at the BZ boundary X. The hole and electron carriers calculated from the enclosed FS volumes are perfectly compensated, and the carrier compensation is unaffected by temperature. We further reveal that LaSb is topologically trivial but shares many similarities with the Weyl semimetal TaAs family in the bulk electronic structure. Based on these results, we have examined the mechanisms that have been proposed so far to explain the near-quadratic XMR in semimetals.

Realization and manipulation of ZnO nanorod arrays on sapphire substrates using a catalyst-free metalorganic chemical vapor deposition technique.

Single-crystalline ZnO nanorod arrays (ZNRs) were grown by metalorganic chemical vapor deposition on ZnO buffer/sapphire substrate without using any metal catalyst. The density of vertically aligned ZNRs was found to govern by the morphology and thickness of buffer layer. That is to say, the ZnO buffer layer can be used as the nucleation template to control the growth direction and density of the ZNRs. In addition, by controlling the diethyl zinc flow rate, we can manipulate the size, crystal, and optical quality of ZNRs. Finally, the possible growth mechanism of ZNRs was discussed in detail.

Effect of cage charges on multiphoton absorptions: first-principles study on metallofullerenes Sc(2)C(2)@C(68) and Sc(3)N@C(68).

A combined method of the time-dependent density functional theory (TDDFT) and sum-overstate (SOS) formula was implemented to model multiphoton absorption spectra, including two-photon absorption (2PA) and three-photon absorption (3PA), of Sc(2)C(2)@C(68) and Sc(3)N@C(68) endohedral metallofullerenes (EMFs). This method has been proved to be effective by comparisons between the calculated and experimental results of trans-4,4'-bis[diphenylamino]stilbene. It was found that the multiphoton absorption cross sections were larger for Sc(2)C(2)@C(68) than that of Sc(3)N@C(68). The electronic origin of multiphoton absorption has been identified with respect to the molecular orbitals involved in charge transfer process. It shows that the increase of pi-charges on the cage of C(68) results in a large multiphoton absorption cross section in EMFs.

Revealing 'plasmaron' feature in DySb by optical spectroscopy study.

We report magnetic susceptibility, resistivity and optical spectroscopy study on single crystal sample DySb. It exhibits extremely large magnetoresistance (XMR), and a magnetic phase transition from paramagnetic (PM) to antiferromagnetic (AFM) state at about 10 K. A 'screened' plasma edge at about 4000 cm-1 is revealed by optical measurement, which suggests that the material has a low carrier density. With decreasing temperature, the 'screened' plasma edge shows a blue shift, possibly due to a decrease of the effective mass of carriers. Notably, an anomalous temperature dependent midinfrared absorption feature is observed in the vicinity of the 'screened' plasma edge. In addition, it can be connected to the inflection point in the real part of the dielectric function [Formula: see text], the frequency of which exactly tracks the temperature dependent 'screened' plasma frequency. This phenomena can be explained by the appearance of a coupled electron-plasmon 'plasmaron' feature.

First-principles study: size-dependent optical properties for semiconducting silicon carbide nanotubes.

Using first-principles calculations, we investigate the effect of tube size on optical properties of the zigzag, armchair, and chiral SiC nanotubes. The results indicate that the optical spectra of SiC nanotubes are dependent on the diameter and chirality, and that optical anisotropy is observed for different light polarizations. For a given chirality of SiCNTs, redshifts or blueshifts of the peaks in the dielectric function and energy loss function with increasing tube diameter are possible due to the competition between the size effect and pi orbitals overlapping, and the shifts become smaller as the tube diameter increases. The unusual optical properties of semiconducting SiC nanotubes present an opportunity for applications in electro-optical devices.

Huddle test measurement of a near Johnson noise limited geophone.

In this paper, the sensor noise of two geophone configurations (L-22D and L-4C geophones from Sercel with custom built amplifiers) was measured by performing two huddle tests. It is shown that the accuracy of the results can be significantly improved by performing the huddle test in a seismically quiet environment and by using a large number of reference sensors to remove the seismic foreground signal from the data. Using these two techniques, the measured sensor noise of the two geophone configurations matched the calculated predictions remarkably well in the bandwidth of interest (0.01 Hz-100 Hz). Low noise operational amplifiers OPA188 were utilized to amplify the L-4C geophone to give a sensor that was characterized to be near Johnson noise limited in the bandwidth of interest with a noise value of 10-11 m/Hz at 1 Hz.

A human prostatic epithelial model of hormonal carcinogenesis.

The effects of stromal and hormonal environment on the immortalized but nontumorigenic human prostatic epithelial cell line BPH-1 were investigated in an in vivo model. BPH-1 cells were recombined with rat urogenital sinus mesenchyme (UGM), and the tissue recombinants were grafted to the renal capsule of adult male athymic mouse hosts. BPH-1 + UGM recombinants formed solid branching epithelial cords with a well-defined basement membrane. The cords canalized to form ductal structures. The mesenchymal cells formed thick sheets of well-differentiated smooth muscle surrounding the epithelium, reinforcing the idea that the epithelium dictates the patterning of prostatic stromal cells. When hosts carrying BPH-1 + UGM tissue recombinants were exposed to testosterone propionate and 17-beta-estradiol (T + E2), the tissue recombinants responded by forming invasive carcinomas, demonstrating mixed, predominantly squamous as well as adenocarcinomatous (small acinar and mucinous) differentiation. When either untreated or T + E2-treated hosts were castrated, epithelial apoptosis was observed in the grafts. When tumors were removed and regrafted to fresh hosts they grew rapidly. Tumors were serially regrafted through six generations. Histologically these tumors consisted largely of focally keratinizing squamous cell carcinoma with high-grade malignant cytological features. BPH-1 cells grown in the absence of UGM survived at the graft site but did not form tumors or organized structures. This behavior was not influenced by the presence or absence of T + E2 stimulation. These data show that an immortalized, nontumorigenic human prostatic epithelial cell line can undergo hormonal carcinogenesis in response to T + E2 stimulation. In addition, the data demonstrate that the stromal environment plays an important role in mediating hormonal carcinogenesis.

Theoretical study on the photophysical properties of hexapyrrolidine C60 adducts with Th, D3, and S6 symmetries.

The equilibrium geometries of three isomeric hexapyrrolidine C(60) adducts with T(h), D(3), and S(6) symmetries are optimized by means of the B3LYP method at the 6-31G basis sets in this paper. On the basis of the optimized structures, the excited state and third-order nonlinear optical properties, such as third-harmonic generation (THG), electric-field-induced second-harmonic generation (EFISHG), and degenerate four-wave mixing (DFWM), and two-photon absorption (TPA) cross sections, delta, are calculated by using the TDB3LYP model based on the 6-31G level coupled with the sum-over-states (SOS) method. The computational results show that the transition energies from S(0) to S(1) of the T(h) hexaadduct and the D(3) hexaadduct have a remarkable blue shift by comparison with that of the C(60) parent. These results are in agreement with experimental ones. However, the first singlet excitation energy of the S(6) hexaadduct has a red shift compared with that of the C(60) parent. Accordingly, we predict that different positions located by six addends may result in the different spectrum properties. Finally, the two-photon absorption cross sections indicate that the largest average value of resonant TPA, delta, of the D(3) hexaadduct has a red shift compared with those of the T(h) and S(6) hexaadducts.

Effects of internal and external scatter on the build-up characteristics of Monte Carlo calculated absorbed dose for electron irradiation.

The effects of internal and external scatter on surface, build-up and depth dose characteristics simulated by Monte Carlo code EGSnrc for varying field size and SSD for a 10 MeV monoenergetic electron beam with and without an accelerator model are extensively studied in this paper. In particular, sub-millimetre surface PDD was investigated. The percentage depth doses affected significantly by the external scatter show a larger build-up dose. A forward shifted Dmax depth and a sharper fall-off region compared to PDDs with only internal scatter considered. The surface dose with both internal and external scatter shows a marked decrease at 110 cm SSD, and then slight further changes with the increasing SSD since few external scattered particles from accelerator model can reach the phantom for large SSDs. The sharp PDD increase for the 5 cm x 5 cm field compared to other fields seen when only internal scatter is considered is significantly less when external scatter is also present. The effect of external scatter on surface PDD is more pronounced for large fields than small fields (5 cm x 5 cm field).

Acute and chronic effects of the pesticide amitraz on alpha 2-adrenoceptors in mouse brain.

There is increasing evidence to suggest that several effects of the formamidine pesticide amitraz (AMZ) in mammals are mediated by its interaction with alpha 2-adrenoceptors. AMZ has been shown to inhibit the binding of [3H]clonidine, a specific ligand for alpha 2-adrenoceptors to mouse brain in vitro and after administration in vivo. In the present study we have further investigated and characterized the effects of acute and chronic administration of AMZ on brain alpha 2-adrenoceptors in mice. AMZ caused a dose-dependent inhibition of [3H]clonidine binding. This inhibition was long-lasting (more than 48 h) following a relatively high dose of AMZ (75 mg/kg), while it was of short duration (2 h) following low doses (7.5 and 12.5 mg/kg). The time course of inhibition of [3H]clonidine binding was correlated with the plasma levels of AMZ and/or its active metabolites, measured with a novel radioreceptor binding technique. The alteration of [3H]clonidine binding was due to a decrease in alpha 2-adrenoceptor affinity, with no change in the density of binding sites, and was reversible in vitro upon repeated washing of the membrane preparation. Repeated administration of 7.5 mg/kg or 12.5 mg/kg AMZ, to yield a total dose of 75 mg/kg, showed no evidence of a cumulative effect on brain alpha 2-adrenoceptors.

Formamidine pesticides and alpha 2-adrenoceptors: studies with amitraz and chlordimeform in rats and development of a radioreceptor binding assay.

The interaction of the formamidine pesticides chlordimeform (CDM) and amitraz (AMZ) with rat brain alpha2-adrenoceptors was investigated. Both compounds inhibited the binding of 3H-clonidine and 3H-yohimbine in vitro with IC50 values of 62-68 microM (CDM) and 95-110 nM (AMZ). In vivo administration of AMZ and CDM caused a dose-dependent inhibition of 3H-clonidine binding in rat forebrain. The inhibition was short-lasting (24 hr) following CDM administration, while after AMZ recovery of 3H-clonidine binding occurred only after 72 hr. Good correlations were found between inhibition of brain 3H-clonidine binding by the formamidines and "plasma equivalents" of these compounds and/or their biologically active metabolites, as measured by a new radioreceptor assay. These results suggest that 1) formamidines can interact in vivo with brain alpha 2-adrenoceptors when administered at doses previously shown to cause toxic effects on the central nervous system: and 2) this effect is reversible, both in vivo and in vitro, and appears to be linked to the presence of the formamidines and/or their active metabolites at the receptor sites.

Effects of treatment distance and field size on build-up characteristics of Monte Carlo calculated absorbed dose for electron irradiation.

Surface, build-up and depth dose characteristics of a monoenergetic electron point source simulated by Monte Carlo code MCNP4c for varying field size and SSD are extensively studied in this paper. MCNP4c (Monte Carlo N-Particle Transport Code System) has been extensively used in clinical dose simulation for its versatility and powerful geometrical coding tool. A sharp increase in PDD is seen with the Monte Carlo Modelling immediately at the surface within the first 0.2 mm. This effect cannot be easily measured by experimental instruments for electron contamination, and may lead to a clinical underdosing of the basal cell layer, which is one of the most radiation sensitive layers and the main target for skin carcinogenesis. A high percentage build-up dose for electron irradiation was shown. No significant effects in surface PDDs were modelled with different SSD values from 95 cm to 125 cm. Three depths were studied in detail, these being 0.05 mm, the lower depth of the basal cell layer; 0.95 mm, the lower depth of the dermal layer; and 0.95 cm, a position within the subcutaneous tissue. Results showed only small surface PDD differences were modelled for SSD variations from 95 cm to 125 cm and field sizes variation from the values between 5 cm and 10 cm squares to 25 cm. When the field side length is smaller than this, the surface dose shows an increasing trend by about 7% at 5 x 5 cm2.

A theoretical investigation of hyperpolarizability for small Ga(n)As(m) (n + m = 4-10) clusters.

In this paper, the second and third order polarizabilities of small Ga(n)As(m) (n + m=4-10) clusters are systematically investigated using the time dependent density functional theory (TDDFT)6-311+G* combined with the sum-over-states method (SOSTDDFT6-311+G*). For the static second order polarizabilities, the two-level term (beta(vec.2)) makes a significant contribution to the beta(vec) for all considered Ga(n)As(m) clusters except for the Ga3As4 cluster. And, for the static third order polarizabilities, the positive channel (gamma(II)) makes a larger contribution to gamma(tot) than the negative channel (gamma(I)). Similar to the cubic GaAs bulk materials, the small Ga(n)As(m) cluster assembled materials exhibit large second order (1 x 10(-6) esu) and third order susceptibilities (5 x 10(-11) esu). The dynamic behavior of beta(-2omega; omega, omega) and gamma(-3omega; omega, omega, omega) show that the small Ga(n)As(m) cluster will be a good candidate of nonlinear optical materials due to the avoidance of linear resonance photoabsorption.

Modeling of configurations and third-order nonlinear optical properties of methyl silsesquioxanes.

Configuration optimizations, excited state properties, and the frequency-dependent third-order nonlinear optical polarizabilities have been investigated on a series of methyl-silsesquioxane (MeT) cages [CH(3)SiO(1.5)](n) (n=4, 6, 8, and 10) using ab initio quantum mechanical methods coupled with the sum-over-states methods. The obtained electronic absorption spectra show a redshift as the cage size increases, and the absorption spectra are assigned as charge transfers from oxygen p type to silicon s type atomic orbitals. The calculated average third-order polarizabilities of in the three optical physical processes (third-harmonic generation, the electric-field-induced second-harmonic generation, and degenerate four-wave mixing) have wide nonresonance regions. For all the considered species, the values of gamma decrease in the order of [MeT](4)>[MeT](8)(C(2v))=[MeT](10)>[MeT](6)>[MeT](8)(O(h)).

Indinavir urolithiasis.

Indinavir sulfate is a protease inhibitor that has been found to be extremely effective in increasing CD4+ cell counts and in decreasing HIV-RNA titers in patients with HIV and AIDS. However, patients receiving indinavir also have been noted to have a significant risk for developing urolithiasis. Published reports of indinavir urolithiasis estimate its incidence at between 4 and 13%. Indinavir has a high urinary excretion with poor solubility in a physiologic pH solution. Consequently, patients develop urinary stones that are principally composed of indinavir or of a mixture of indinavir and other substances, such as calcium oxalate. Similar to other forms of urolithiasis, acute flank pain and hematuria are the typical symptoms of indinavir urolithiasis. Indinavir urolithiasis is unique in that computed tomography, which was once thought to be efficacious in identifying all urinary calculi, is not useful in imaging stones that are composed of pure indinavir. Indinavir urolithiasis generally responds to a conservative regimen of hydration, pain control, and the temporary discontinuation of the medication. Only a minority of patients need surgical intervention. Approximately 10% of patients ultimately need to discontinue indinavir therapy altogether. Indinavir is an antiviral agent that has a significant role in the treatment of AIDS. Although urolithiasis is a significant side effect of indinavir use, limiting its clinical application is not the answer. Rather, physicians need to know more about indinavir urolithiasis to help their patients cope with its potential complications.

Osteoporosis in Colles fracture.

Previous studies of bone density in patients with Colles fracture have been inconclusive. We measured bone density at the second metacarpal in 36 postmenopausal women with Colles fracture. The patients were found to have highly significant (P < 0.01) or significant (P < 0.05) differences in the parameters of bone density compared with controls matched for age. The results suggest that osteoporosis is of definite relevance to the etiology of Colles fracture in postmenopausal women.

Adaptative responses of tobacco callus cells to simulated microgravity by compensation.

Under the rotation-induced gravity compensation, growth rate of callus was repressed by about 44%. Its osmotic and water potential declined by about 22 and 27% respectively. The content of soluble sugar was enhanced by about 123% and that of K+ by about 25%. The permeability of plasmic membrane increased and the lipid peroxidation intensified. When the callus grown under clinostatting were subcultured and returned to stationary conditions, the growth rates and related physiological indications were restored again to or near to the level of the control (SC). Electron microscopic studies showed that nuclear membrane was invaginated so deeply that some of the nuclei were like a starfish. Rough endoplasmic reticulum was diminished. The smooth one observed on the surface of slices was lengthened by almost 8.9 times of the control (SC), the longest one reached to 42 micrometers. They were often concentrated in a corner of the cell. Some of them were rolled into tube-shapes. The amyloplasts were without starch grain. It is assumed that the responses of plant cell to microgravity may be a sort of tolerable unloading reaction on endomembrane system.