Controlled Frustration Release on the Kagome Lattice by Uniaxial-Strain Tuning.

It is predicted that strongly interacting spins on a frustrated lattice may lead to a quantum disordered ground state or even form a quantum spin liquid with exotic low-energy excitations. However, a controlled tuning of the frustration strength, separating its effects from those of disorder and other factors, is pending. Here, we perform comprehensive ^{1}H NMR measurements on Y_{3}Cu_{9}(OH)_{19}Cl_{8} single crystals revealing an unusual Q[over →]=(1/3×1/3) antiferromagnetic state below T_{N}=2.2 K. By applying in situ uniaxial stress, we break the symmetry of this disorder-free, frustrated kagome system in a controlled manner yielding a linear increase of T_{N} with strain, in line with theoretical predictions for a distorted kagome lattice. In-plane strain of ≈1% triggers a sizable enhancement ΔT_{N}/T_{N}≈10% due to a release of frustration, demonstrating its pivotal role for magnetic order.

Dipolar order in an amphidynamic crystalline metal-organic framework through reorienting linkers.

Amphidynamic crystals, which possess crystallinity and support dynamic behaviours, are very well suited to the exploration of emergent phenomena that result from the coupling on the dynamic moieties. Here, dipolar rotors have been embedded in a crystalline metal-organic framework. The material consists of Zn(II) nodes and two types of ditopic bicyclo[2.2.2]octane-based linkers-one that coordinates to the Zn clusters through two 1,4-aza moieties, and a difluoro-functionalized derivative (the dipolar rotor) that coordinates through linked 1,4-dicarboxylate groups instead. Upon cooling, these linkers collectively order as a result of correlated dipole-dipole interactions. Variable-temperature, frequency-dependent dielectric measurements revealed a transition temperature Tc = 100 K, when a rapidly rotating, dipole-disordered, paraelectric phase transformed into an ordered, antiferroelectric one in which the dipole moments of the rotating linkers largely cancelled each other. Monte Carlo simulations on a two-dimensional rotary lattice showed a ground state with an Ising symmetry and the effects of dipole-lattice and dipole-dipole interactions.

Constraints on the superconducting order parameter in Sr2RuO4 from oxygen-17 nuclear magnetic resonance.

Phases of matter are usually identified through spontaneous symmetry breaking, especially regarding unconventional superconductivity and the interactions from which it originates. In that context, the superconducting state of the quasi-two-dimensional and strongly correlated perovskite Sr2RuO4 is considered to be the only solid-state analogue to the superfluid 3He-A phase1,2, with an odd-parity order parameter that is unidirectional in spin space for all electron momenta and breaks time-reversal symmetry. This characterization was recently called into question by a search for an expected 'split' transition in a Sr2RuO4 crystal under in-plane uniaxial pressure, which failed to find any such evidence; instead, a dramatic rise and a peak in a single-transition temperature were observed3,4. Here we use nuclear magnetic resonance (NMR) spectroscopy of oxygen-17, which is directly sensitive to the order parameter via hyperfine coupling to the electronic spin degrees of freedom, to probe the nature of superconductivity in Sr2RuO4 and its evolution under strain. A reduction of the Knight shift is observed for all strain values and at temperatures below the critical temperature, consistent with a drop in spin polarization in the superconducting state. In unstrained samples, our results contradict a body of previous NMR work reporting no change in the Knight shift5 and the most prevalent theoretical interpretation of the order parameter as a chiral p-wave state. Sr2RuO4 is an extremely clean layered perovskite and its superconductivity emerges from a strongly correlated Fermi liquid, and our work imposes tight constraints on the order parameter symmetry of this archetypal system.

Icariin promotes mouse hair follicle growth by increasing insulin-like growth factor 1 expression in dermal papillary cells.

BACKGROUND: Icariin is a major flavonoid isolated from Epimedium spp. leaves (Epimedium Herba), and has multiple pharmacological functions, including anti-angiogenesis, anti-oxidant, anti-inflammatory and immunoprotective effects. AIM: To investigate whether icariin can stimulate growth of hair follicles in mice and the underlying mechanism. METHODS: In vitro, the effect of icariin on hair growth was assessed by using a vibrissae hair follicle (VHF) organ-culture model. The proliferation of hair matrix keratinocytes and the expression of insulin-like growth factor (IGF)-1 in follicles were examined by double immunostaining for 5-bromo-2'-deoxyuridine and IGF-1, in the presence or absence of icariin. Dermal papilla cells (DPCs) were cultured and IGF-1 level was measured by reverse transcription-PCR and ELISA after icariin treatment. In vivo, the effect of icariin on hair growth was examined by gavage feeding of icariin to mice whose backs had been depilated, and the conversion of telogen to anagen hair was observed. RESULTS: Treatment with icariin promoted hair shaft elongation, prolonged the hair cycle growth phase (anagen) in cultured VHFs, and accelerated transition of hair cycle from telogen to anagen phase in the dorsal skin of mice. There was significant proliferation of matrix keratinocytes and an increased level of IGF-1 in cultured VHFs. Moreover, icariin treatment upregulated IGF-1 mRNA expression in DPCs and increased IGF-1 protein content in the conditioned medium of DPCs. CONCLUSIONS: These results suggest that icariin can promote mouse hair follicle growth via stimulation of IGF-1 expression in DPCs.

Effects of extracellular matrix on the growth characteristics of human dermal papillae cells in vitro.

BACKGROUND: In humans, dermal papillae cells (DPCs) are surrounded by basal membranes. However, conventional in vitro culture conditions for DPCs do not include extracellular matrix (ECM). AIM: To investigate the effects of different ECM types on the characteristics of cultured human DPCs. METHODS: Freshly isolated human DPCs were inoculated onto plates precoated with type IV collagen, fibronectin, Matrigel or hyaluronate. Cell migration, growth and viability were measured. Real-time quantitative (q)PCR and western blotting were used to detect the influence of different ECM types on the expression of DPC-specific biomarkers. RESULTS: In planar culture, type IV collagen and fibronectin had a beneficial effect on the migration, aggregation and viability of DPCs, in contrast to Matrigel and hyaluronate. Real-time qPCR revealed that significantly increased expression of mRNA was seen only for neural cell adhesion molecule (NCAM) and α-smooth muscle actin (α-SMA) in the Matrigel group, whereas versican, NCAM and α-SMA all decreased significantly in the hyaluronate group. In the type IV collagen and fibronectin groups, mRNA expression of the above genes did not change significantly. Western blotting indicated that there were no significant differences in expression of the above proteins between the four groups and the control group. CONCLUSION: In planar culture, exogenous ECM types (Matrigel, type IV collagen, hyaluronate and fibronectin) changed the growth characteristics of DPCs, but they did not affect the characteristics associated with the biological functions of DPCs.

The worldwide spread of ciprofloxacin-resistant Shigella sonnei among HIV-infected men who have sex with men, Taiwan.

Ciprofloxacin-resistant shigellosis outbreaks among men who have sex with men (MSM) have not been reported in Asia. During 3 March to 6 May 2015, the Notifiable Disease Surveillance System detected nine non-imported Shigella sonnei infections among human immunodeficiency virus (HIV) -infected Taiwanese MSM. We conducted a molecular epidemiological investigation using a 1 : 5 matched case-control study and laboratory characterizations for the isolates. Of the nine patients, four reported engagement in oral-anal sex before illness onset. Shigellosis was associated with a syphilis report within 12 months (adjusted odds ratio (aOR) 8.6; 95% CI 1.05-70.3) and no HIV outpatient follow-up within 12 months (aOR 22.3; 95% CI 2.5-201). Shigella sonnei isolates from the nine patients were all ciprofloxacin-resistant and the resistance was associated with S83L and D87G mutations in gyrA and S80I mutation in parC. The nine outbreak isolates were discriminated into two closely related pulsed-field gel electrophoresis (PFGE) genotypes and seven 8-locus multilocus variable-number tandem repeat analysis (MLVA8) types that suggest multiple sources of infections for the outbreak and possible under-recognition of infection among Taiwanese MSM. The outbreak isolates were characterized to be variants of the intercontinentally transmitted SS18.1 clone, which falls into the globally prevalent phylogenetic sub-lineage IIIb. Inter-database pattern similarity searching indicated that the two PFGE genotypes had emerged in the USA and Japan. The epidemiological characteristics of this outbreak suggest roles of risky sexual behaviours or networks in S. sonnei transmission. We urge enhanced surveillance and risk-reduction interventions regionally against the interplay of HIV and shigellosis among MSM.

Unconventional interplay between heterovalent dopant elements: Switch-and-modulator band-gap engineering in (Y, Co)-Codoped CeO2 nanocrystals.

We report the experimental observation and theoretical explanation of an unconventional interplay between divalent Co and trivalent Y dopants, both of which incur oxygen vacancies in the CeO2 host that has predominantly tetravalent Ce cations. The Co dopant atoms were experimentally found to act as a switch that turns on the dormant effect of Y-modulated band-gap reduction. As revealed by density functional theory (DFT) calculations with structures verified by synchrotron-radiation x-ray measurements, a Co 3d band that hybridizes with Ce 4f band was lowered due to reduced O 2p repulsion arising from oxygen vacancies incurred by Y doping and therefore gave rise to the observed band-gap narrowing effect. Such switch-and-modulator scheme for band-gap engineering in nanocrystal materials can lead to important applications in environmental protection and solar energy harvesting technologies.

A simple and rapid model for hair-follicle regeneration in the nude mouse.

BACKGROUND: Methods for hair-follicle regeneration are important tools for investigating signalling and cytokines during hair-follicle morphogenesis and cycling. Several animal models for hair reconstitution have been established; however, these models have several shortcomings. AIM: To develop a simple and rapid model for hair induction in nude mouse. METHODS: We designed an improved flap model (IFM) for hair regeneration based on the existing flap assay. Histological sections and scanning electron microscopy were used to evaluate the regenerated hair. The fates of grafted cells were traced by fluorescence. The time required for hair induction was analysed and compared. RESULTS: IFM produced a large number of normal hairs, and the time required for hair induction using IFM was 20.67 ± 0.67 days, compared with 29.33 ± 0.67 days for the traditional flap assay. CONCLUSIONS: The time required for hair regeneration is considerably shortened with IFM. We speculate that this is due to increased blood supply at the transplantation sites.

Psoriasis as initiator or amplifier of the systemic inflammatory march: impact on development of severe vascular events and implications for treatment strategy.

BACKGROUND: Psoriasis is a systemic disease associated with metabolic disorders and vascular complications. Both psoriasis and metabolic disorders are associated with systemic inflammation. We hypothesized that the sequence of events between the onset of psoriasis and metabolic disorder may affect the risk for subsequent development of vascular complications. METHODS: Nested case-control study was performed using the Taiwan National Health Insurance database. Accordingly, a total of 8180 psoriatic patients and 163,600 controls were included. Psoriasis was considered as the initiator of inflammatory march if metabolic disorder, including hypertension, diabetes mellitus and dyslipidemia, developed after onset of psoriasis. In patients with pre-existing metabolic disorder, psoriasis was considered as the amplifier of inflammatory march. RESULTS: In patients whose psoriasis served as the disease initiator, a lower risk for developing vascular disease (HR = 1.49; 95% CI = 1.11-2.00 and HR = 1.64; 95% CI = 1.31-2.05 for cerebrovascular and cardiovascular events, respectively) was found compared with patients whose psoriasis served as the disease amplifier (HR = 2.26; 95% CI = 1.72-2.97 and HR = 2.78; 95% CI = 2.26-3.42 for cerebrovascular and cardiovascular events, respectively) after adjusting for age and gender. In terms of treatment implications, methotrexate was associated with reduced risk for developing cerebrovascular event (HR = 0.22; 95% CI = 0.05-0.88) only in patients with psoriasis serving as the disease amplifier. CONCLUSIONS: Our results suggested that two scenarios of systemic inflammatory marches are present among psoriatic patients with metabolic disorder and judicious use of methotrexate may reduce the risk of cerebrovascular event, especially when psoriasis served as the disease amplifier of the systemic inflammatory march.

Inflammation induction of Dickkopf-1 mediates chondrocyte apoptosis in osteoarthritic joint.

OBJECTIVE: Dysregulated Wnt signaling appears to modulate chondrocyte fate and joint disorders. Dickkopf-1 (DKK1) regulates the pathogenesis of skeletal tissue by inhibiting Wnt actions. This study examined whether DKK1 expression is linked to chondrocyte fate in osteoarthritis (OA). METHOD: Articular cartilage specimens harvested from nine patients with knee OA and from six controls with femoral neck fracture were assessed for DKK1, interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), Bad, Bax, Bcl2 and caspase-3 expression by real time-polymerase chain reaction (RT-PCR) and immunohistochemistry. Apoptotic chondrocytes were detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labelling (TUNEL) and 4', 6-dianidino-2-phenylindole dihydrochloride (DAPI) staining. Human chondrocyte cultures were treated with recombinant IL-1beta and monoclonal DKK1 antibody to determine whether DKK1 impairs chondrocyte survival. RESULTS: Expression of DKK1 correlated with inflammatory cytokine levels (IL-1beta and TNF-alpha expressions), proapoptosis regulators (Bad and caspase-3 expressions) and TUNEL staining in OA cartilage tissues. The IL-1beta induced expressions of DKK1, Bax, Bad and caspase-3-dependent apoptosis of chondrocyte cultures. Neutralization of DKK1 by monoclonal DKK1 antibody significantly abrogated IL-1beta-mediated caspase-3 cleavage and apoptosis and reversed chondrocyte proliferation. Recombinant DKK1 treatment impaired chondrocyte growth and promoted apoptosis. By suppressing nuclear beta-catenin accumulation and Akt phosphorylation, DKK1 mediated IL-1beta promotion of chondrocyte apoptosis. CONCLUSION: Chondrocyte apoptosis correlates with joint OA. Expression of DKK1 contributes to cartilage deterioration and is a potent factor in OA pathogenesis. Attenuating DKK1 may reduce cartilage deterioration in OA.

Organellar genome analysis of rye (Secale cereale) representing diverse geographic regions.

Rye (Secale cereale) is an important diploid (2n = 14, RR) crop species of the Triticeae and a better understanding of its organellar genome variation can aid in its improvement. Previous genetic analyses of rye focused on the nuclear genome. In the present study, the objective was to investigate the organellar genome diversity and relationships of 96 accessions representing diverse geographic regions using chloroplast (cp) and mitochondrial (mt) DNA PCR-RFLPs. Seven cpDNA and 4 mtDNA coding and noncoding regions were amplified using universal cpDNA and mtDNA primer pairs. Each amplified fragment was digested with 13 different restriction enzymes. mtDNA analysis indicated that the number of polymorphic loci (20) was low and genetic differentiation (GST) was 0.60, excluding the outgroups (hexaploid wheat, Triticum aestivum, 2n = 6x = 42, AABBDD; triticale, xTriticosecale Wittmack, 2n = 6x = 42, AABBRR). cpDNA analysis revealed a low level of polymorphism (40%) among the accessions, and GST was 0.39. Of the 96 genotypes studied, 70 could not be differentiated using cpDNA PCR-RFLPs even though they are from different geographic regions. This is most likely due to germplasm exchange, indicating that genotypes might have a common genetic background. Two cpDNA and 3 mtDNA fragments were significantly correlated to the site of germplasm collection. However, there was no clear trend. These results indicate that the level of organellar polymorphism is low among the cultivated rye genotypes. The cpDNA and mtDNA PCR-RFLP markers used in the present study could be used as molecular markers in rye genetics and breeding programs.

Acetabular revision with morsellised allogenic bone graft and a cemented metal-backed component.

Failure of total hip arthroplasty with acetabular deficiency occurred in 55 patients (60 hips) and was treated with acetabular revision using morsellised allograft and a cemented metal-backed component. A total of 50 patients (55 hips) were available for clinical and radiological evaluation at a mean follow-up of 5.8 years (3 to 9.5). No hip required further revision of the acetabular component because of aseptic loosening. All the hips except one had complete incorporation of the allograft demonstrated on the radiographs. A complete radiolucent line of > 1 mm was noted in two hips post-operatively. A good to excellent result occurred in 50 hips (91%). With radiological evidence of aseptic loosening of the acetabular component as the end-point, the survivorship at a mean of 5.8 years after surgery was 96.4%. The use of impacted allograft chips in combination with a cemented metal-backed acetabular component and screw fixation can achieve good medium-term results in patients with acetabular bone deficiency.

Comparison of NAT1, NAT2 and GSTT2-2 activities in normal and neoplastic human breast tissues.

In this study, arylamine N-acetyltransferases, NATs (E.C.2.3.1.5) and glutathione-S-transferase-T2-2, GSTT2-2 (E.C.2.5.1.18) enzyme activities in the breast tumor and surrounding tumor-free tissues of 22 female breast cancer patients with infiltrating ductal carcinoma were measured. The possible impacts of grade of malignancy, chemotherapy treatment, estrogen receptor status and menopausal status on all enzyme activities were evaluated. The results showed that, both NAT2 and GSTT2-2 display significant differences between tumor and tumor-free breast tissues, while no difference was observed in NAT1. Grade of malignancy seems to be positively associated with NAT1 and negatively associated with GSTT2-2. Though, both NAT2 and GSTT2-2 have increased mean tumor activities, the grade of malignancy, chemotherapy status, menopausal status or estrogen receptor status are not correlated statistically.

Determination of magnetic susceptibility of various ion-labeled red blood cells by means of analytical magnetapheresis.

Analytical magnetapheresis is a newly developed technique for separating magnetically susceptible particles. The magnetically susceptible particles are deposited on a bottom plate after flowing through a thin (< 0.05 cm) separation channel under a magnetic field applied perpendicular to the flow. Particles with various magnetic susceptibilities can be selectively deposited and separated by adjusting the applying magnetic force and flow rates. Magnetic susceptibility is an important parameter for magnetic separation. Magnetic susceptibility determination of various ion-labeled red blood cells (RBCs) using analytical magnetapheresis with a simple theoretical treatment is reported in this study. Susceptibility determination is based on the balance between maximal channel flow rate and magnetically induced flow rate for deposition. We tried a new approach to determine particle magnetic susceptibilities using a balance of magnetic and drag forces to control magnetically induced particle velocities. The Er3+, Fe3+, Cu2+, Mn2+, Co2+, and Ni2+ ions were used to label RBC at various labeling concentrations for susceptibility determination. The susceptibilities determined for various ion-labeled RBC under two magnetic field intensities fell within a 10% range. The average viabilities of various ion-labeled RBCs were 96.1 +/- 0.8%. The susceptibility determination generally took less than 10 min. Determined susceptibilities from analytical magnetapheresis differed by 10% from reference measurements using a superconducting quantum interference device (SQUID) magnetometer. The cost and time for analysis is much less using analytical magnetapheresis. This technique can provide a simple, fast, and economical way for particle susceptibility determinations.

Diffusion mechanism of hydrogen in amorphous silicon: ab initio molecular dynamics simulation.

The mechanism of H migration in amorphous Si has remained an unresolved problem. The main issue is the small activation energy (1.5 eV) relative to the known strength of Si-H bonds (2-3.5 eV). We report first-principles finite-temperature simulations which demonstrate vividly that H is not released spontaneously, as proposed by most models, but awaits the arrival of a floating bond (FB). The "migrating species" is an FB-H complex, with H jumping from Si to Si and the FB literally floating around it. Migration stops when the FB veers away.

Non-Stoner continuum in the double exchange model.

Exact diagonalization studies of the double exchange model indicate the existence of continuum states in the single-spin-flip channel that overlap the magnons at very low energies (approximately 10(-2) eV) and extend to high energies (approximately eV). This picture differs dramatically from the prevalent view, where there are the magnons, plus the Stoner continuum at the high-energy scale, with nothing in between. The relevance of these new continuum states to inelastic neutron scattering and optical properties is discussed.

Determination of aqueous chlorothalonil with solid-phase microextraction and gas chromatography.

Solid-phase microextraction coupled with GC-electron-capture detection was examined to analyze aqueous chlorothalonil residuals. The optimal conditions for chlorothalonil pre-concentration such as fiber polarity, temperature, salt addition, absorption time, as well as the interference were investigated in detail. In addition, the thermal desorption conditions in the injector were also systematically optimized. Experimental results indicated that an extraction with a 100-microm polydimethylsiloxane fiber for 40 min under conditions of 1250 rpm stirring rate, room temperature, and adding high concentration salt offered an optimal result. The thermal desorption of chlorothalonil at 240 degrees C for 3 min (including fiber regeneration) offered the best sensitive detection. A standard addition method for calibration was recommended to reduce the deviation from matrix interference. The proposed method provided a simple and rapid analytical procedure for chlorothalonil in water bodies with detection limits of 2.86 microg/l for distilled water, 3.06 microg/l for ground water, 4.77 microg/l for tap water, and 9.23 microg/l for farm water. The relative standard deviations were all below 3.0% (n=6) besides the farm water being below 9.2%. The calibration graph in the range of 5 to 200 microg/l is linear with very good correlation coefficient (r=0.999), and r=0.983 for farm water. Application was illustrated by the analysis of water samples collected from tap water, ground water and farm water in the southern Taichung area.

Amplified potentiometric determination of pK(00), pK(0), pK(l), and pK(2) of hydrogen sulfides with Ag(2)S ISE.

The chemical capacitor theory has been applied to accurately determine dissociation constants of H(2)S with the Ag(2)S ion-selective electrode (ISE). The theory's principle is based on the measurement of the change in electrode charge density as a result of protonated or unprotonated sulfide adsorbed on the electrode surface. This charge density is related to the potential. Connection of each individual capacitor in series amplifies the potential according to the equation, E(total)=E(1)+E(2)+E(3)+cdots, three dots, centeredE(n). As the charges of individual capacitors are concentrated to one capacitor area, the charge density rises, and the potential increases. The pK(00), pK(0), pK(1), and pK(2) are reported as 1.8, 2.12, 7.05, and 12.0, respectively. The pK(00) and pK(0) are reported here for the first time. The pK(1) agrees well with the literature values; however, the pK(2) differs from those reported recently under extreme conditions. Reasons for disproving the unreasonably high pK(2)>>17-19 values are given based on calculations. Mainly, when pK(2)>>17-19, the experimental results do not fit the equilibrium equations, pH=(pK(1)+pK(2))/2, pK(1)=(pK(0)+pK(2))/2, and pH=pK(2)+log(HS(-))/(S(2-)).

Spectrophotometric titration of zirconium in siliceous materials.

An accurate and selective complexometric titration procedure based upon a spectrophotometrically detected end-point has been developed for the determination of zirconium in glasses, glass-ceramics and refractories. A p-bromomandelic acid separation step for zirconium imparts excellent selectivity to the procedure. The method is particularly important for the 1-5% concentration range where a simple, accurate and selective method for the determination of zirconium has been lacking.