On the road to metallic nanoparticles by rational design: bridging the gap between atomic-level theoretical modeling and reality by total scattering experiments

The extent to which current theoretical modeling alone can reveal real-world metallic nanoparticles (NPs) at the atomic level was scrutinized and demonstrated to be insufficient and how it can be improved by using a pragmatic approach involving straightforward experiments is shown. In particular, 4 to 6 nm in size silica supported Au(100-x)Pd(x) (x = 30, 46 and 58) explored for catalytic applications is characterized structurally by total scattering experiments including high-energy synchrotron X-ray diffraction (XRD) coupled to atomic pair distribution function (PDF) analysis. Atomic-level models for the NPs are built by molecular dynamics simulations based on the archetypal for current theoretical modeling Sutton-Chen (SC) method. Models are matched against independent experimental data and are demonstrated to be inaccurate unless their theoretical foundation, i.e. the SC method, is supplemented with basic yet crucial information on the length and strength of metal-to-metal bonds and, when necessary, structural disorder in the actual NPs studied. An atomic PDF-based approach for accessing such information and implementing it in theoretical modeling is put forward. For completeness, the approach is concisely demonstrated on 15 nm in size water-dispersed Au particles explored for bio-medical applications and 16 nm in size hexane-dispersed Fe48Pd52 particles explored for magnetic applications as well. It is argued that when "tuned up" against experiments relevant to metals and alloys confined to nanoscale dimensions, such as total scattering coupled to atomic PDF analysis, rather than by mere intuition and/or against data for the respective solids, atomic-level theoretical modeling can provide a sound understanding of the synthesis-structure-property relationships in real-world metallic NPs. Ultimately this can help advance nanoscience and technology a step closer to producing metallic NPs by rational design.

Screening of polymorphisms located in the FGF20 and TMEM175 genes in North Chinese Parkinson's disease patients

Genome-wide association studies have reported numerous susceptibility loci for Parkinson's disease (PD). However, there have been few replication studies examining these loci in northern Chinese populations. To evaluate the relationships among 3 polymorphic markers located in the fibroblast growth factor 20 and transmembrane protein 175 genes and the genetic susceptibility to PD in northern Chinese subjects, 2 single nucleotide polymorphisms, and 1 insertion/deletion marker (rs591323 in FGF20; rs6599388 and rs142821586 in transmembrane protein 175 near the G-associated kinase/diacylglycerol kinase theta region) were investigated in 313 PD patients and 318 matched controls. Mismatched multiplex polymerase chain reaction-restriction fragment length polymorphism analysis as well as sequence-specific primer polymerase chain reaction and restriction fragment length polymorphism assays were performed. The genotypic frequency of rs591323 differed significantly between the patient and control groups; however, neither rs6599388 nor rs142821586 was associated with PD. We corrected the Hardy-Weinberg disequilibrium for rs6599388, which was previously reported to be common in 4 Asian descent populations into equilibrium status by simultaneously genotyping rs6599388 and rs142821586. In summary, we found that rs591323 was associated with PD but rs6599388 and rs142821586 were not associated with PD in a northern Chinese population.

Efficient coupling of double-metal terahertz quantum cascade lasers to flexible dielectric-lined hollow metallic waveguides

The growth in terahertz frequency applications utilising the quantum cascade laser is hampered by a lack of targeted power delivery solutions over large distances (>100 mm). Here we demonstrate the efficient coupling of double-metal quantum cascade lasers into flexible polystyrene lined hollow metallic waveguides via the use of a hollow copper waveguide integrated into the laser mounting block. Our approach exhibits low divergence, Gaussian-like emission, which is robust to misalignment error, at distances > 550 mm, with a coupling efficiency from the hollow copper waveguide into the flexible waveguide > 90%. We also demonstrate the ability to nitrogen purge the flexible waveguide, increasing the power transmission by up to 20% at 2.85 THz, which paves the way for future fibre based terahertz sensing and spectroscopy applications.

Prevalence of Metabolically Healthy Obese and Metabolically Obese but Normal Weight in Adults Worldwide: A Meta-Analysis

The objective of the present study was to summarize the prevalence and influencing factors of metabolically healthy obese (MHO) and metabolically obese but normal weight (MONW) among people ≥ 18 years old in the general population worldwide. We searched for studies of the prevalence of MHO and MONW published in English and Chinese up to October 2013. Pooled prevalence estimates were calculated by a random-effects model according to a Q test. The effects of gender, region, age, sample size, smoking, and alcohol consumption on MHO and MONW were analyzed. Differences between subgroups were assessed by chi-square test. Publication bias was estimated by Egger's test. Studies of MHO and MONW showed heterogeneity (I(2)=99.4% and I(2)=99.7%, respectively). The overall prevalence of MHO and MONW was 7.27% (95% CI 5.92-8.90%) and 19.98% (95% CI 16.54-23.94%), respectively. American populations had the highest MHO prevalence and European populations the highest MONW prevalence. Different patterns of MHO and MONW were observed in the subgroup analysis with respect to gender, age, sample size, smoking, alcohol consumption, and metabolically healthy criteria. The prevalence of both MHO and MONW were affected by gender, region, age, sample size, smoking, alcohol consumption, and metabolically healthy criteria, but studies showed high heterogeneity.

Sub-Kelvin magnetic and electrical measurements in a diamond anvil cell with in situ tunability

We discuss techniques for performing continuous measurements across a wide range of pressure-field-temperature phase space, combining the milli-Kelvin temperatures of a helium dilution refrigerator with the giga-Pascal pressures of a diamond anvil cell and the Tesla magnetic fields of a superconducting magnet. With a view towards minimizing remnant magnetic fields and background magnetic susceptibility, we characterize high-strength superalloy materials for the pressure cell assembly, which allows high fidelity measurements of low-field phenomena such as superconductivity below 100 mK at pressures above 10 GPa. In situ tunability and measurement of the pressure permit experiments over a wide range of pressure, while at the same time making possible precise steps across abrupt phase transitions such as those from insulator to metal.

The implant infection paradox: why do some succeed when others fail? Opinion and discussion paper

Biomaterial-implants are frequently used to restore function and form of human anatomy. However, the presence of implanted biomaterials dramatically elevates infection risk. Paradoxically, dental-implants placed in a bacteria-laden milieu experience moderate failure-rates, due to infection (0.0-1.1%), similar to the ones of joint-arthroplasties placed in a near-sterile environment (0.1-1.3%). Transcutaneous bone-fixation pins breach the immune-barrier of the epidermis, exposing underlying sterile-tissue to an unsterile external environment. In contrast to dental-implants, also placed in a highly unsterile environment, these pins give rise to relatively high infection-associated failure-rates of up to 23.0%. Herein, we attempt to identify causes as to why dental-implants so often succeed, where others fail. The major part of all implants considered are metal-made, with similar surface-finishes. Material choice was therefore discarded as underlying the paradox. Antimicrobial activity of saliva has also been suggested as a cause for the success of dental-implants, but was discarded because saliva is the implant-site-fluid from which viable bacteria adhere. Crevicular fluid was discarded as it is largely analogous to serum. Instead, we attribute the relative success of dental-implants to (1) ability of oral tissues to heal rapidly in the continuous presence of commensal bacteria and opportunistic pathogens, and (2) tolerance of the oral immune-system. Inability of local tissue to adhere, spread and grow in presence of bacteria and an intolerant immune-system are identified as the likely main causes explaining the susceptibility of other implants to infection-associated failure. In conclusion, it is the authors' belief that new anti-infection strategies for a wide range of biomaterial-implants may be derived from the relative success of dental-implants.

FBXL10 contributes to the progression of nasopharyngeal carcinoma via involving in PI3K/mTOR pathway

Our study aimed to investigate whether F-box and leucine-rich repeat protein 10 (FBXL10) may play a pivotal role in nasopharyngeal carcinoma (NPC) development via involving in PI3K/mTOR pathway. We .constructed an FBXL10 expression vector (pcDNA3.1-FBXL10). Then pcDNA3.1-FBXL10 and FBXL10-specific siRNA (siFBXL10) were transfected into human NPC cell line CNE1 and SUNE1 with Lipofectamine ® 2000. Moreover, cells were treated with PI3K inhibitor BEZ235. Besides, MTT assay and flow cytometry were respectively used to explore cell proliferation and apoptosis in vitro. Finally, the expression of key proteins involved in PI3K/AKT/mTOR pathway, such as P-AKT, AKT, P-P70, P70, P-Myc and Myc, were determined by western blot. Western blot analysis displayed that FBXL10 was overexpressed and suppressed after transfected by pcDNA3.1-FBXL10 and siFBXL10, respectively. Moreover, cell proliferation in FBXL10 overexpression group gradually increased compared with control group while obviously decreased in siFBXL10 group. Moreover, volume of apoptotic cells significantly increased with knockdown of FBXL10, which was similar with BEZ235 treatment. Besides, knockdown of FBXL10 decreased the expression levels of PI3K/mTOR pathway-related proteins, which was also similar with BEZ235 treatment. Notably, BEZ235 and siFBXL10 treatment induced significant increase of cell apoptosis and decrease of the expression levels of PI3K/mTOR pathway-related proteins than that only treated with siFBXL10. These findings indicate that FBXL10 may play a pivotal role in promoting cell proliferation and inhibiting cell apoptosis in NPC cells via targeting or functioning synergistically with PI3K/mTOR pathway. Knockdown of FBXL10 may be a novel therapeutic strategy for the treatment of NPC.

Systemic or intra-amygdala infusion of an endocannabinoid CB1 receptor antagonist AM251 blocked propofol-induced anterograde amnesia

Propofol is well-known for its anterograde amnesic actions. However, a recent experiment showed that propofol can also produce retrograde memory enhancement effects via an interaction with the endocannabinoid CB1 system. Therefore, the authors hypothesized that the regulating effect of propofol on the endocannabinoid CB1 system might also decrease the anterograde amnesic effect of propofol under some conditions, which might be a risk factor for intraoperative awareness. Since, the basolateral amygdala (BLA) has been confirmed to mediate propofol-induced anterograde amnesia and the BLA contains a high concentration of CB1 receptors, the authors investigated whether and how the endocannabinoid system, particularly the CB1 receptor within BLA, influences propofol-induced anterograde amnesia. Male Sprague-Dawley rats trained with inhibitory avoidance (IA) were systematically pre-trained using a memory-impairing dose of propofol (25 mg/kg). Before propofol administration, rats received an intraperitoneal injection of a CB1 receptor antagonist AM251 (1 mg/kg or 2 mg/kg) or a bilateral intra-BLA injection of AM251 (0.6 ng or 6 ng per 0.5 μl). Twenty-four hours after IA training, the IA retention latency was tested. It was found that systemic or intra-BLA injection of a non-regulating dose of AM251 (2 mg/kg or 6 ng per 0.5 μl, respectively) blocked the memory-impairing effect of propofol. These results indicate that the anterograde amnesic effect of propofol is mediated, in part, by activation of the CB1 cannabinoid receptors in the BLA.

Hollow metallic waveguides integrated with terahertz quantum cascade lasers

We present the realization of a compact, monolithically integrated arrangement of terahertz quantum cascade lasers with hollow metallic cylindrical waveguides. By directly mounting a copper pipe to the end facet of a double metal waveguide, it was possible to significantly improve the far field emission from such a sub-wavelength plasmonic mode, while preserving the characteristic performance of the laser. Careful alignment of the quantum cascade laser and the hollow waveguide is required in order to prevent the excitation of higher order/mixed modes as predicted with a high degree of accuracy by a theoretical model. Finally, this approach proved to be a superior method of beam shaping when compared to other in situ arrangements, such as a silicon hyper-hemispherical lens glued to the facet, which are presented.

A novel way to statistically analyze morphologic changes in Dmp1-null osteocytes

Recent studies have revealed multiple roles of osteocytes in bone metabolism. However, detailed analyses of the embedded osteocytes in bone structure are still limited because of the high mineral content around these cells. In this study, we developed an innovative technique, the "FITC-Imaris technique", which combines FITC ([2, 5]-Fluorescein isothiocyanate), confocal microscopy and Imaris software. With this method, we could not only visualize the 3-D morphology of embedded osteocytes, but more importantly, we were able to statistically quantitate the osteocyte structure in the cell surface area, total cell volume, and dendrite numbers. Furthermore, we made a side-by-side comparison of the new method with the acid-etched SEM imaging technique, a common imaging method for studies of osteocyte morphology with a much smaller cell depth (< 3 μm). Finally, we used the FITC-Imaris technique to show both the morphological and statistical differences in the osteocyte structure between the Dmp1-null mice (the osteomalacia model) and their age-matched control littermates. We expect that this newly developed technique will become a powerful tool to disclose more roles that osteocytes play in bone health and diseases.

The -675 4G/5G polymorphism in the PAI-1 gene may not contribute to the risk of PCOS

OBJECTIVE

The association between the -675 4G/5G polymorphism in PAI-1 gene and PCOS has been studied with inconclusive results. We sought to investigate this inconsistency by performing a comprehensive meta-analysis on the polymorphism.

MATERIALS AND METHODS

Searches were performed in the PubMed, Embase, CNKI and Wanfang databases, covering all papers. Statistical analysis was performed using Revman5.2 and STATA11.0 software. A total of 11 case-control studies were extracted on the polymorphism involving 1861 PCOS cases and 1187 controls.

RESULTS

The results showed that, no significant increased/decreased risk were found for the polymorphism for PCOS: OR = 1.03, 95% CI = 0.77-1.66, p = 0.52 for 4G4G + 4G5G vs. 5G5G; OR = 0.99, 95% CI = 0.66-1.49, p = 0.96 for 4G4G vs. 5G5G + 4G5G; OR = 1.08, 95% CI = 0.66-1.79, p = 0.76 for 4G4G vs. 5G5G; OR = 1.11, 95% CI = 0.78-1.58, p = 0.56 for 4G5G vs. 5G5G; OR = 1.00, 95% CI = 0.71-1.41, p = 0.99 for 4G vs. 5G. In the further subgroup analysis by ethnicity, we did not find a significant association between the polymorphism for PCOS risk in either Asians or Europeans.

CONCLUSIONS

Our findings demonstrated that -675 4G/5G polymorphism in the PAI-1 gene might not be a risk factor for the development of PCOS.

Remote monitoring of nuclear power plants in Baden-Wuerttemberg

As part of its responsibilities as nuclear supervisory authority, the Ministry of the Environment, Climate Protection and the Energy Sector Baden-Wuerttemberg (UM) operates a computer-based system for remote monitoring of nuclear power plants (NPPs) (KFUe, Kernreaktor-Fernüberwachung). In addition to the Baden-Wuerttemberg NPPs located at Philippsburg, Neckarwestheim and the disused Obrigheim, those in foreign locations close to the border area, i.e. Fessenheim in France, and Leibstadt and Beznau in Switzerland, are monitored. The KFUe system provides several methods to evaluate and present the measured data as well as to ensure compliance of threshold limits and safety objectives. For the UM, it serves as an instrument of the nuclear supervision. In case of a radioactive release, the authorities responsible for civil protection can use dispersion calculations in order to identify potentially affected areas and to initiate protective measures for the population. Beyond the data collected at the plant sites, various international radiation and meteorological measuring networks are integrated in the KFUe. The State Institute for Environment, Measurements and Nature Protection (LUBW), the technical operator of the KFUe, runs its own special monitoring network for ambient gamma dose rate and nuclide specific activity concentration measurements in the vicinity of each NPP. This article gives an overview of the solution to combine data of different sources on a single screen: dose rate networks, dose rate traces measured by car, airborne gamma spectra of helicopters, mobile dose rate probes, grid data of weather forecasts, dispersion calculations, etc.

Enhancing glass-forming ability via frustration of nano-clustering in alloys with a high solvent content

The glass-forming ability (GFA) of alloys with a high-solvent content such as soft magnetic Fe-based and Al-based alloys is usually limited due to strong formation of the solvent-based solid solution phase. Herein, we report that the GFA of soft magnetic Fe-based alloys (with >70 at.% Fe to ensure large saturation magnetization) could be dramatically improved by doping with only 0.3 at.% Cu which has a positive enthalpy of mixing with Fe. It was found that an appropriate Cu addition could enhance the liquid phase stability and crystallization resistance by destabilizing the α-Fe nano-clusters due to the necessity to redistribute the Cu atoms. However, excessive Cu doping would stimulate nucleation of the α-Fe nano-clusters due to the repulsive nature between the Fe and Cu atoms, thus deteriorating the GFA. Our findings provide new insights into understanding of glass formation in general.