Optically probing the fine structure of a single Mn atom in an InAs quantum dot

We report on the optical spectroscopy of a single InAs/GaAs quantum dot (QD) doped with a single Mn atom in a longitudinal magnetic field of a few Tesla. Our findings show that the Mn impurity is a neutral acceptor state A^0 whose effective spin J=1 is significantly perturbed by the QD potential and its associated strain field. The spin interaction with photo-carriers injected in the quantum dot is shown to be ferromagnetic for holes, with an effective coupling constant of a few hundreds of micro-eV, but vanishingly small for electrons.Comment: 5 pages, 3 figure

Dynamic nuclear polarization of a single charge-tunable InAs/GaAs quantum dot

We report on the dynamic nuclear polarization of a single charge-tunable self-assembled InAs/GaAs quantum dot in a longitudinal magnetic field of $\sim$0.2T. The hyperfine interaction between the optically oriented electron and nuclei spins leads to the polarization of the quantum dot nuclei measured by the Overhauser-shift of the singly-charged excitons ($X^{+}$ and $X^{-}$). When going from $X^{+}$ to $X^{-}$, we observe a reversal of this shift which reflects the average electron spin optically written down in the quantum dot either in the $X^{+}$ state or in the final state of $X^{-}$ recombination. We discuss a theoretical model which indicates an efficient depolarization mechanism for the nuclei limiting their polarization to ~10%.Comment: 4+ pages, 3 figure

Chemically bound gold nanoparticle arrays on silicon: assembly, properties and SERS study of protein interactions

A highly reproducible and facile method for formation of ordered 2 dimensional arrays of CTAB protected 50 nm gold nanoparticles bonded to silicon wafers is described. The silicon wafers have been chemically modified with long-chain silanes terminated with thiol that penetrate the CTAB bilayer and chemically bind to the underlying gold nanoparticle. The silicon wafer provides a reproducibly smooth, chemically functionalizable and non-fluorescent substrate with a silicon phonon mode which may provide a convenient internal frequency and intensity calibration for vibrational spectroscopy. The CTAB bilayer provides a potentially biomimetic environment for analyte, yet allows a sufficiently small nanoparticle separation to achieve a significant electric field enhancement. The arrays have been characterized using SEM and Raman spectroscopy. These studies reveal that the reproducibility of the arrays is excellent both between batches (< 10% RSD) and across a single batch (< 5% RSD). The arrays also exhibit good stability, and the effect of temperature on the arrays was also investigated. The interaction of protein and amino acid with the nanoparticle arrays was investigated using Raman microscopy to investigate their potential in bio-SERS spectroscopy. Raman of phenylalanine and the protein bovine pancreatic trypsin inhibitor, BPTI were studied using 785 nm excitation, coincident with the surface plasmon absorbance of the array. The arrays exhibit SERS enhancements of the order of 2.6 x 104 for phenylalanine, the standard deviation on the relative intensity of the 1555 cm-1 mode of phenylalanine is less than 10% for 100 randomly distributed locations across a single substrate and less than 20% between different substrates. Significantly, comparisons of the Raman spectra of the protein and phenlyalanine in solution and immobilized on the nanoparticle arrays indicates that the protein is non-randomly orientated on the arrays. Selective SERS enhancements suggest that aromatic residues penetrate through the bilayer inducing conformational changes in the protein

Titanium (IV) Oxide Nanotubes in Design of Active SERS Substrates for High Sensitivity Analytical Applications: Effect of Geometrical Factors in Nanotubes and in Ag-n Deposits

In this chapter, we summarize the results of recent investigations into TiO2 nanotubular oxide layers on Ti metal loaded with Ag nanoparticles, which act as efficient surface plasmon resonators. These Ag-n/TiO2 NT/Ti composite layers appear to be useful as platforms for precise surface analytical investigations of minute amounts of numerous types of organic molecules: pyridine (Py), mercaptobenzoic acid (MBA), 5-(4-dimethylaminobenzylidene) rhodamine (DBRh) and rhodamine (R6G); such investigations are known as surface enhanced Raman Spectroscopy (SERS). Geometrical factors related to the nanotubes and the silver deposit affect the SERS activity of the resulting composite layers. The results presented here show that, for a carefully controlled amount of Ag-n deposit located mainly on the tops of titania nanotubes, it is possible to obtain high-quality, reproducible SERS spectra for probe molecules at an enhancement factor of 105–106. This achievement makes it possible to detect organic molecules at concentrations as low as, e.g., 10−9 M for R6G molecules. SEM investigations suggest that the size of the nanotubes, and both the lateral and perpendicular distribution of Ag-n (on the tube tops and walls), are responsible for the SERS activity. These features of the Ag-n/TiO2 NT/Ti composite layer provide a variety of cavities and slits which function as suitable resonators for the adsorbed molecules

Chromium in urothelial carcinoma of the bladder

Introduction and objectives Many epidemiological and experimental studies report a strong role of chemical carcinogens in the etiology of bladder cancer. However, the involvement of heavy metals in tumourigenesis of urothelial carcinoma of the bladder has been poorly investigated. Therefore, the aim of this study was to examine the relationship between chromium (Cr) and bladder cancer. Material and Methods Chromium concentration in two 36-sample series of bladder cancer tissue and sera from patients with this neoplasm were matched with those of a control group. The amount of trace elements in every tissue sample was determined using atomic absorption spectrometry. This was correlated with tumour stage. Results While the median chromium concentration levels reached statistically higher values in the bladder cancer tissue, compared with the non-cancer tissue (99.632ng/g and 33.144ng/g, respectively; p<0.001), the median Cr levels in the sera of the patients with this carcinoma showed no statistical difference when compared to those of the control group (0.511μg/l and 0.710μg/l, respectively; p=0.408). The median levels of Cr in the bladder tissue, depending on the stage of the tumour, compared with the tissue without the neoplasm, observed the same relationship for both non-muscle invasive and muscle-invasive tumours (p<0.001 and p<0.01, respectively). Conclusions This study shows that patients with urothelial carcinoma of the bladder had higher tissue Cr levels than people without tumour, while no difference was found in the Cr serum levels between the two groups of patients under investigation

Siłownia telekomunikacyjna 48 V; 1200 - 4800 A. Referaty Problemowe, 1987, zeszyt 83

W artykule podano opis systemu siłowni telekomunikacyjnej prądu stałego o napięciu wyjściowym 48 V i prądzie 4800 A, wykonanej w ramach pracy planowej CPBR 47.A.Zamieszczono krótki opis poszczególnych części składowych artykułu, będących rozszerzeniem tematu, opisano podstawowe podzespoły siłowni, a więc: zespoły prostownikowe oraz nową generację przetwornic dodawczych

Hidden Signature for DTW Signature Verification in Authorizing Payment Transactions, Journal of Telecommunications and Information Technology, 2010, nr 4

Traditional use of dynamic time warping for signature verification consists of forming some dissimilarity measure between the signature in question and a set of “template signatures”. In this paper, we propose to replace this set with the hidden signature and use it to calculate the normalized errors of signature under verification. The approach was tested on the MCYT database, using both genuine signatures and skilled forgeries. Moreover, we present the real-world application of the proposed algorithm, namely the complete biometric system for authorizing payment transactions. The authorization is performed directly at a point of sale by the automatic signature verification system based on the hidden signature

Persistent Sexual Arousal Syndrome

Zespół przetrwałego pobudzenia seksualnego (PSAS) opisany po raz pierwszy w 2001 roku i zakwalifikowany do grupy zaburzeń pożądania jest czynnikiem zakłócającym funkcjonowanie kobiety i znacznie wpływającym na jakość jej życia. W niniejszej pracy na podstawie dostępnego piśmiennictwa omówiono stan wiedzy na temat etiologii, patofizjologii, rozpoznawania oraz obecne zalecenia dotyczące leczenia PSAS.Persistent Sexual Arousal Syndrome (PSAS) - described for the first time in 2001 and qualified as a desire disorder, an important factor interfering woman's functioning and significantly impairing her quality of life. In this review the authors present current state of knowledge on etiology, patophysiology, diagnosis and current therapy guidelines of PSAS

Penile fracture with associated urethral trauma — case report

Złamanie prącia jest rzadko spotykanym urazem narządów płciowych, który wymaga pilnego leczenia operacyjnego. W pracy przedstawiono analizę przypadku złamania prącia z towarzyszącym urazem cewki moczowej u 51-letniego mężczyzny. Leczenie operacyjne polegało na zszyciu pękniętej osłonki szwem ciągłym oraz zespoleniu cewki moczowej szwami pojedynczymi. Leczenie operacyjne złamania prącia daje dobre efekty czynnościowe.Penile fracture is rare genital injury that requires urgent surgical treatment. The authors described case report of penile fracture with an associated urethral trauma in 51-year old man. Surgical treatment consisted of suturing the cracked tunica albuginea using continuous suture and combining the urethra using single sutures. Surgical treatment of penile fracture gives good functional results