High-power and narrow-linewidth optimizations of mid-infrared quantum cascade lasers

A novel design of high peak power mid-infrared quantum cascade lasers has been modeled, implemented and characterized. Emitting 23.5 W peak power at room temperature, it demonstrated high beam quality, owing to the gain guiding effect, which has not been reported in quantum cascade lasers before. A new concept of constant power laser current source has been proposed and designed in a circuit performing reduction of optical frequency noise by reducing the amount of the electrical power fluctuations generated by the laser itself. Significant reduction of optical frequency noise has been measured without locking the laser frequency to any optical reference. Quantum cascade lasers operating at two frequencies simultaneously have been characterized in terms of frequency stability. A high value of correlation observed between instant frequencies of the two modes allowed to implement a scheme with indirect frequency locking, where the mode not locked to an optical reference experienced frequency noise reduction while the other one was used for stabilization

Design of bidirectional frictional behaviour for tactile contact using ellipsoidal asperity micro-textures

Tactile perception and friction can be modified by producing a deterministic surface topography. Change of surface feature arrangement and texture symmetry can produce an anisotropic frictional behaviour. It is generally achieved through skin hysteresis by promoting its deformation. This work investigates whether a bidirectional friction can be created with microscale ellipsoidal asperity textures, thus relying on the adhesive component of friction. For this purpose, four textured samples with various asperity dimensions were moulded with a silicone rubber having an elastic modulus comparable to that of the skin. Coefficient of friction measurements were conducted in-vivo in two sliding directions with a range of normal loads up to 4 N. Finite element method (FEM) was used to study elastic deformation effects, explain the observed friction difference, and predict surface material influence. Measurements performed perpendicular to the asperity major radii showed consistently higher friction coefficients than that during parallel sliding. For the larger asperity dimensions, a change of the sliding direction increased friction up to a factor of 2. The numerical analysis showed that this effect is mostly related to elastic asperity deflection. Bidirectional friction differences can be further controlled by asperity dimensions, spacing, and material properties.</p

Fluorescent optical fiber sensors for cell viability monitoring

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.A new simple method for non-invasive cell culture viability monitoring based on vital fluorescent stains is introduced, and its efficiency for long-term experiments on cells is demonstrated. In contrast to common methods for cell viability control, which are usually either destructive (like flow-type counters or dead cells coloring and counting), or hardly quantitative like fluorescent microscopy, the method described is automated, does not require the removal of cells from their growth area and is sensitive enough to deal with as low as tens of cells

Plan of the "Out of State Town" of Dokshitsa (Archival Document 1836)

Секция II ИСТОРИЯ АРХИТЕКТУРЫ, ГРАДОСТРОИТЕЛЬСТВА И ИСКУССТВАПланы города Докшицы отражают процессы изменений небольшого белорусского города на рубеже ХVIII–ХIХ столетий в условиях изменения государственности, административного упорядочивания территориями, последствий войн и пожаров. Отражают они и уникальность ситуации, которую создало разделение города на две части границей двух губерний, – Минской и Виленской.=The plans of the town of Dokshitsy reflect the processes of changes in a small Belarusian town at the turn of the 18th – 19th centuries in the context of changes in statehood, adminis-trative regulation of territories, the consequences of wars and fires. They also reflect the uniqueness of the situation created by the division of the city into two parts by the border of two provinces - Minsk and Vilno

Novopolotsk: Format and Images of the Architecture of Commercial Objects

Секция I : Архитектура и градостроительство в современных условияхВ статье рассматриваются процессы формирования объектов торговли в городе Новополоцке от начала его создания в 1958 г до современности. Показано, что архитектура торговых зданий содействует сохранению сложившейся масштабности застройки при одно-временном использовании современных средств архитектурной выразительности.=The article discusses the processes of forming trade objects in the city of Novopolotsk from the be-ginning of its creation in 1958 to the present. It is shown that the architecture of commercial buildings contributes to the preservation of the scale of development while using modern means of architectural expressiveness

Plan of the "Out of State Town" of Dokshitsa (Archival Document 1836)

Секция II ИСТОРИЯ АРХИТЕКТУРЫ, ГРАДОСТРОИТЕЛЬСТВА И ИСКУССТВАПланы города Докшицы отражают процессы изменений небольшого белорусского города на рубеже ХVIII–ХIХ столетий в условиях изменения государственности, административного упорядочивания территориями, последствий войн и пожаров. Отражают они и уникальность ситуации, которую создало разделение города на две части границей двух губерний, – Минской и Виленской.=The plans of the town of Dokshitsy reflect the processes of changes in a small Belarusian town at the turn of the 18th – 19th centuries in the context of changes in statehood, adminis-trative regulation of territories, the consequences of wars and fires. They also reflect the uniqueness of the situation created by the division of the city into two parts by the border of two provinces - Minsk and Vilno

Trapping and ground-state cooling of H2+H_2^+

We demonstrate co-trapping and sideband cooling of a $H_2^+ - ^9Be^+$ ion pair in a cryogenic Paul trap. We study the chemical lifetime of $H_2^+$ and its dependence on the apparatus temperature, achieving lifetimes of up to $11^{+6}_{-3} h$ at 10 K. We demonstrate cooling of translational motion to an average phonon number of 0.07(1), corresponding to a temperature of $22(1)\mu K$. Our results provide a basis for quantum logic spectroscopy experiments of $H_2^+$, as well as other light ions such as $HD^+$, $H_3^+$, and $He^+$