Tissue self-affinity and polarized light scattering in the born approximation: a new model for precancer detection

Light scattered from biological tissues can exhibit an inverse power law spectral component. We develop a model based on the Born approximation and von Karman (self-affine) spatial correlation of submicron tissue refractive index to account for this. The model is applied to light scattering spectra obtained from excised esophagi of normal and carcinogen-treated rats. Power law exponents used to fit dysplastic tissue site spectra are significantly smaller than those from normal sites, indicating that changes in tissue self-affinity can serve as a potential biomarker for precancer.     

Numerical discrimination of intrachannel cross-phase modulation and intrachannel four-wave mixing and their respective effect on 40 Gbit/s transmissions

We propose a numerical method to accurately discriminate the influence of the different intrachannel nonlinear effects occurring in 40 Gbit/s optical transmissions, following an analogy with methods used to discriminate WDM interchannel effects. In contrast to other studies showing the predominance of intrachannel cross-phase modulation when low-dispersion fibers are used, in our study intrachannel four-wave mixing is the most penalizing effect in all investigated cases.     

Hexadecapolar Kondo effect in URu2Si2?

We derive the coupling of a localized hexadecapolar mode to conduction electrons in tetragonal symmetry. The derivation can be easily adapted to arbitrary multipoles in an arbitrary environment. We relate our model to the two-channel Kondo (2CK) model and show that for an f(2) configuration a relevant crystal field splitting in addition to the 2CK interaction is intrinsic to tetragonal symmetry. We discuss possible realizations of a hexadecapolar Kondo effect in URu(2)Si(2). Solving our model we find good agreement with susceptibility and specific heat measurements in Th(1-x)U(x)Ru(2)Si(2) (x?1).     

Real time inverse filter focusing through iterative time reversal

In order to achieve an optimal focusing through heterogeneous media we need to build the inverse filter of the propagation operator. Time reversal is an easy and robust way to achieve such an inverse filter in nondissipative media. However, as soon as losses appear in the medium, time reversal is not equivalent to the inverse filter anymore. Consequently, it does not produce the optimal focusing and beam degradations may appear. In such cases, we showed in previous works that the optimal focusing can be recovered by using the so-called spatiotemporal inverse filter technique. This process requires the presence of a complete set of receivers inside the medium. It allows one to reach the optimal focusing even in extreme situations such as ultrasonic focusing through human skull or audible sound focusing in strongly reverberant rooms. But, this technique is time consuming and implied fastidious numerical calculations. In this paper we propose a new way to process this inverse filter focusing technique in real time and without any calculation. The new process is based on iterative time reversal process. Contrary to the classical inverse filter technique, this iteration does not require any computation and achieves the inverse filter in an experimental way using wave propagation instead of computational power. The convergence from time reversal to inverse filter during the iterative process is theoretically explained. Finally, the feasibility of this iterative technique is experimentally demonstrated for ultrasound applications.     

Distortion-free single point imaging of multi-layered composite sandwich panel structures

The results of a magnetic resonance imaging (MRI) investigation concerning the effects of an aluminum honeycomb sandwich panel on the B1 and B0 fields and on subsequent image quality are presented. Although the sandwich panel structure, representative of an aircraft composite material, distorts B0 and attenuates B1, distortion-free imaging is possible using single point (constant time) imaging techniques. A new expression is derived for the error caused by gradient field distortion due to the heterogeneous magnetic susceptibility within a sample and this error is shown not to cause geometric distortion in the image. The origin of the B0 distortion in the sample under investigation was also examined. The graphite-epoxy 'skin' of the panel is the principal source of the B0 distortion. Successful imaging of these structures sets the stage for the development of methods for detecting moisture ingress and degradation within composite sandwich structures.     

Investigation of fill factor losses on 20.2% efficient n‐type mono‐like silicon solar cells with laser contact opening

Large area (243.36 cm²) back‐junction passivated emitter, rear totally diffused (PERT) solar cells with laser contact opening (LCO) on n‐type mono‐like crystalline Si with efficiencies of 20.2% are presented. Boron emitters with high electrical quality (implied open circuit voltage iV_OC up to 700 mV) are formed during a co‐diffusion step using SiO_x:B layers. Increasing the rear metal contact coverage, we observed a decrease in fill factor (FF) instead of the expected increase due to the decrease of the back side series resistance. We show that it can be attributed to recombination centers (RCs) in the space charge region underneath the contact spots inducing an increasing second diode contribution. The presented empirical model for the RCs implemented in Synopsys Sentaurus TCAD allows for a successful reproduction of the FF, pseudo FF and V_OC behaviour with contact coverage. According to this model, the RCs induced by laser ablation and subsequently evaporation of Al have a shallow exponential distribution with a characteristic length of L_T = 0.2 µm and an effective surface density of N *_T0 = 25 cm^–1. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Highly confined hybrid spoof surface plasmons in ultrathin metal-dielectric heterostructures

Highly confined "spoof" surface plasmons (SSPs) are theoretically predicted to exist in a perforated metal film coated with a thin dielectric layer. Strong modes confinement results from the additional waveguiding by the layer. Spectral characteristics, field distribution, and lifetime of these SSPs are tunable by the holes' size and shape. SSPs exist both above and below the light line, offering two classes of applications: "perfect" far-field absorption and efficient emission into guided modes. It is experimentally shown that these plasmonlike modes can turn thin, weakly absorbing semiconductor films into perfect absorbers.     

Organophotocatalytic N-Demethylation of Oxycodone Using Molecular Oxygen

N-Demethylation of oxycodone is one of the key steps in the synthesis of important opioid antagonists like naloxone or analgesics like nalbuphine. The reaction is typically carried out using stoichiometric amounts of toxic and corrosive reagents. Herein, we present a green and scalable organophotocatalytic procedure that accomplishes the N-demethylation step using molecular oxygen as the terminal oxidant and an organic dye (rose bengal) as an effective photocatalyst. Optimization of the reaction conditions under continuous flow conditions using visible-light irradiation led to an efficient, reliable, and scalable process, producing noroxycodone hydrochloride in high isolated yield and purity after a simple workup.     

Antidepressant-like Effects of Combined Fluoxetine and Zinc Treatment in Mice Exposed to Chronic Restraint Stress Are Related to Modulation of Histone Deacetylase

Chronic stress is the key factor contributing to the development of depressive symptoms. Chronic restraint stress (CRS) is well validated and is one of the most commonly used models to induce depressive-like behavior in rodents. The present study aimed to evaluate whether fluoxetine (FLU 5 mg/kg) and zinc (Zn 10mg/kg) given simultaneously induce a more pronounced antidepressant-like effect in the CRS model than both those compounds given alone. Behavioral assessment was performed using the tail suspension and splash tests (TST and ST, respectively). Furthermore, the effects of CRS, FLU and Zn given alone and combined treatment with FLU + Zn on the expression of proteins involved in the apoptotic, inflammatory, and epigenetic processes were evaluated in selected brain structures (prefrontal cortex, PFC; and hippocampus, Hp) using Western blot analysis or enzyme-linked immunosorbent assays (ELISA). The results obtained indicated that three hours (per day) of immobilization for 4 weeks induced prominent depressive symptoms that manifested as increased immobility time in the TST, as well as decreased number and grooming time in the ST. Behavioral changes induced by CRS were reversed by both FLU (5 and 10 mg/kg) or Zn (10 mg/kg). Zinc supplementation (10 mg/kg) slightly increases the effectiveness of FLU (5 mg/kg) in the TST. However, it significantly increased the activity of FLU in the ST compared to the effect induced by FLU and Zn alone. Biochemical studies revealed that neither CRS nor FLU and Zn given alone or in combined treatment alter the expression of proteins involved in apoptotic or inflammatory processes. CRS induced major alterations in histone deacetylase (HDAC) levels by increasing the level of HADC1 and decreasing the level of HADC4 in the PFC and Hp, decreasing the level of HADC6 in the PFC but increasing it in Hp. Interestingly, FLU + Zn treatment reversed CRS-induced changes in HDAC levels in the Hp, indicating that HDAC modulation is linked to FLU + Zn treatment and this effect is structure-specific.     

Synthesis of New Phenolic Derivatives of Quinazolin-4(3H)-One as Potential Antioxidant Agents—In Vitro Evaluation and Quantum Studies

Considering the important damage caused by the reactive oxygen (ROS) and nitrogen (RNS) species in the human organism, the need for new therapeutic agents, with superior efficacy to the known natural and synthetic antioxidants, is crucial. Quinazolin-4-ones are known for their wide range of biological activities, and phenolic compounds display an important antioxidant effect. Linking the two active pharmacophores may lead to an increase of the antioxidant activity. Therefore, we synthesized four series of new hybrid molecules bearing the quinazolin-4-one and phenol scaffolds. Their antioxidant potential was evaluated in vitro, considering different possible mechanisms of action: hydrogen atom transfer, ability to donate electrons and metal ions chelation. Theoretical quantum and thermodynamical calculations were also performed. Some compounds, especially the ortho diphenolic ones, exerted a stronger antioxidant effect than ascorbic acid and Trolox.