Magnon and Phonon Excitations in Nanosized NiO

Single-crystal, microcrystalline and nanocrystalline nickel oxides (NiO) have been studied by Raman spectroscopy. A new band at ~200 cm-1 and TO-LO splitting of the band at 350–650 cm-1 have been found in the spectra of single-crystals NiO(100), NiO(110) and NiO(111). The Raman spectra of microcrystalline (1500 nm) and nanocrystalline (13–100 nm) NiO resemble those of the single crystals. They all contain the two-magnon band at 1500 cm-1, indicating that the oxides remain at room temperature in the antiferromagnetic phase. Besides, a new sharp Raman band has been observed at 500 cm-1 in nanocrystalline NiO. Its temperature dependence suggests the magnetic origin of the band, possibly associated with the one-phonon–one-magnon excitation at the Brillouin zone centre.Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Optical properties of the Ti surface structured by femtosecond laser beam

Wavelength-scaled periodic ripples formed on the Ti surface under the action of femtosecond laser irradiation have been investigated. The ripples were oriented in parallel to the incident light polarization. After initial formation of ripples, the following laser induced chemical transformation of metallic Ti into dielectric compound was established using the Raman scattering data. Weak Wood’s anomaly in the spectra on light diffracted by the structured Ti surface testifies the minor plasmonic activity

Visualization of Nd3+-doped Laf3 Nanoparticles For Near Infrared Bioimaging via Upconversion Luminescence at Multiphoton Excitation Microscopyvisualization of Nd3+-doped Laf3 Nanoparticles For Near Infrared Bioimaging via Upconversion Luminescence at Multiphoton Excitation Microscopy

Recent developments in the field of biophotonics facilitate the raise of interest to inorganic nanoparticles (NPs) doped with Nd 3+ ions, because of their near-infrared (NIR) absorption. These NPs are interesting bioimaging probes for deep tissue visualization, while they can also act as local thermometers in biological tissues. Despite the good possibilities for visualization of NPs with Nd 3+ ions in NIR spectral range, difficulties arise when studying the cellular uptake of these NPs using commercially available fluorescence microscopy systems, since the selection of suitable luminescence detectors is limited. However, Nd 3+ ions are able to convert NIR radiation into visible light, showing upconversion properties. In this paper we found optimal parameters to excite upconversion luminescence of Nd 3+ :LaF 3 NPs in living cells and to compare the distribution of the NPs inside the cell culture of human macrophages THP-1 obtained by two methods. Firstly, by detecting the upconversion luminescence of the NPs in VIS under NIR multiphoton excitation using laser scanning confocal microscopy and secondly, using transmission electron microscopy

ВИЗУАЛИЗАЦИЯ НАНОЧАСТИЦ LaF3, ДОПИРОВАННЫХ Nd3+, ДЛЯ БИОИМИДЖИНГА В БЛИЖНЕМ ИНФРАКРАСНОМ ДИАПАЗОНЕ ПО АП-КОНВЕРСИОННОЙ ЛЮМИНЕСЦЕНЦИИ ПРИ МИКРОСКОПИИ С МУЛЬТИФОТОННЫМ ВОЗБУЖДЕНИЕМ

Recent developments in the field of biophotonics facilitate the raise of interest to inorganic nanoparticles (NPs) doped with Nd3+ ions, because of their near-infrared (NIR) absorption. These NPs are interesting bioimaging probes for deep tissue visualization, while they can also act as local thermometers in biological tissues. Despite the good possibilities for visualization of NPs with Nd3+ ions in NIR spectral range, difficulties arise when studying the cellular uptake of these NPs using commercially available fluorescence microscopy systems, since the selection of suitable luminescence detectors is limited. However, Nd3+ ions are able to convert NIR radiation into visible light, showing upconversion properties. In this paper we found optimal parameters to excite upconversion luminescence of Nd3++:LaF NPs in living cells and to compare the distribution of the NPs inside the cell culture of human macrophages THP-1 obtained by two methods. Firstly, by detecting the upconversion luminescence of the NPs inVIS under NIR multiphoton excitation using laser scanning confocal microscopy and secondly, using transmission electron microscopy.Последние разработки в области биофотоники способствуют повышению интереса к неорганическим наночастицам (НЧ), допированным ионами Nd3+, из-за их поглощения в ближнем инфракрасном (БИК) спектральном диапазоне. Эти НЧ являются перспективными зондами для глубокой визуализации тканей, в то же время они могут служить локальными термометрами в биологических тканях. Несмотря на хорошие возможности визуализации НЧ с ионами Nd3+ в БИК спектральном диапазоне, при изучении внутриклеточного распределения этих НЧ с использованием коммерчески доступных флуоресцентных микроскопических систем возникают трудности из-за ограниченности выбора подходящих детекторов люминесценции. Однако, ионы Nd3+ способны преобразовывать БИК излучение в видимый свет, демонстрируя ап-конверсионные свойства. В этой работе мы определили оптимальные параметры для возбуждения ап-конверсионной люминесценции НЧ Nd3+: LaF в живых клетках и сравнили распределение НЧ внутри клеток культуры человеческих макрофагов THP-1, полученное двумя методами. Во-первых, путем регистрации ап-конверсионной люминесценции НЧ в видимом диапазоне при многофотонном возбуждении в БИК диапазоне спектра с использованием лазерной сканирующей конфокальной микроскопии и, во-вторых, с использованием просвечивающей электронной микроскопии

НЕИНВАЗИВНАЯ ОЦЕНКА ЛОКАЛЬНОЙ ТЕМПЕРАТУРЫ НАГРЕВА БИОТКАНЕЙ ПОД ДЕЙСТВИЕМ ЛАЗЕРНОГО ИЗЛУЧЕНИЯ ПО СПЕКТРАМ ЛЮМИНЕСЦЕНЦИИ ИОНОВ Nd3+

Laser hyperthermia is one of the promising methods for treatment of oncological diseases. For routine clinical use of hyperthermia, it is necessary to control the uniformity and localization of heat within the tumor. Local heating can be achieved by using special thermal agents, such as nanoparticles doped with rare-earth ions. Measurement of the temperature of the thermal agents will allow timely regulation of the applied laser radiation excitation power and optimization of the hyperthermia process.The paper presents the results of a study on the non-invasive determination of the YPO4 nanoparticles doped with Nd3+ temperature with sensitivity of 0.2% °С-1 in 30-60°С temperature range. The temperature of the nanoparticles was calculated from the Nd3+ luminescence spectra in the 800-1000 nm range under excitation into 4F5/2 energy state by 805 nm laser. A calibration procedure for recalculating the ratio of the luminescence intensities from the Stark sublevels of the 4F3/2 Nd3+ state into the values of the real NP temperature in accordance with the Boltzmann distribution is given. An algorithm for calculating luminescence intensities for individual Stark components is proposed. After calculating the intensities corresponding to each individual Stark component, all the intensities related to the transition from the upper and lower Stark sublevels of the 4F3/2 state are summed, and then their ratio is calculated. The resulting ratio is normalized to the value of the ratio at room temperature and, in accordance with the calibration dependence, is recalculated into the NP heating temperature. It was demonstrated that the investigated 1%Nd3+:YPO4 nanoparticles can be used as "primary” thermometers that do not require additional recalibration to evaluate the temperature in the range used for hyperthermia.Одним из перспективных методов лечения онкологических заболеваний является метод лазерной гипертермии. Для рутинного клинического использования гипертермии необходимо контролировать однородность и локальность нагрева внутри опухоли. Добиться локального нагрева можно при использовании специальных термоагентов, в качестве которых могут выступать наночастицы (НЧ), допированные редкоземельными ионами. Измерение температуры термоагентов в режиме реального времени позволит своевременно регулировать подаваемую возбуждающую мощность лазерного излучения и оптимизировать режимы гипертермии.В работе представлены результаты исследования по неинвазивному определению температуры НЧ YPO4, допированных ионами Nd3+, c чувствительностью 0,2% °С-1 в диапазоне температур 30-60°С. Температура НЧ рассчитывалась по спектрам люминесценции Nd3+ в диапазоне 800-1000 нм при возбуждении на уровень 4F5/2 лазерным излучением 805 нм. Приведена процедура калибровки для пересчета отношения интенсивностей люминесценции со штарковских подуровней состояния 4F3/2 Nd3+ в значения реальной температуры НЧ в соответствии с распределением Больцмана. Предложен алгоритм расчета интенсивностей люминесценции для отдельных штарковских компонент. После вычисления интенсивностей, соответствующих каждой отдельной штарковской компоненте, происходит суммирование всех интенсивностей, относящихся к переходу с верхнего и с нижнего штарковских подуровней состояния 4F3/2, а затем вычисляется их отношение. Полученное отношение нормируется на значение отношения при комнатной температуре и в соответствии с калибровочной зависимостью пересчитывается в температуру нагрева НЧ. Продемонстрировано, что исследуемые НЧ Nd3+:YPO4 могут быть использованы в качестве так называемых «первичных» термометров, не требующих дополнительной перекалибровки для оценки температуры в диапазоне температур, используемом при гипертермии

The violent youth of bright and massive cluster galaxies and their maturation over 7 billion years

In this study, we investigate the formation and evolution mechanisms of the brightest cluster galaxies (BCGs) over cosmic time. At high redshift (z ∼ 0.9), we selected BCGs and most massive cluster galaxies (MMCGs) from the Cl1604 supercluster and compared them to low-redshift (z ∼ 0.1) counterparts drawn from the MCXC meta-catalogue, supplemented by Sloan Digital Sky Survey imaging and spectroscopy. We observed striking differences in the morphological, colour, spectral, and stellar mass properties of the BCGs/MMCGs in the two samples. High-redshift BCGs/MMCGs were, in many cases, star-forming, late-type galaxies, with blue broad-band colours, properties largely absent amongst the low-redshift BCGs/MMCGs. The stellar mass of BCGs was found to increase by an average factor of 2.51 ± 0.71 from z ∼ 0.9 to z ∼ 0.1. Through this and other comparisons, we conclude that a combination of major merging (mainly wet or mixed) and in situ star formation are the main mechanisms which build stellar mass in BCGs/MMCGs. The stellar mass growth of the BCGs/MMCGs also appears to grow in lockstep with both the stellar baryonic and total mass of the cluster. Additionally, BCGs/MMCGs were found to grow in size, on average, a factor of ∼3, while their average Sérsic index increased by ∼0.45 from z ∼ 0.9 to z ∼ 0.1, also supporting a scenario involving major merging, though some adiabatic expansion is required. These observational results are compared to both models and simulations to further explore the implications on processes which shape and evolve BCGs/MMCGs over the past ∼7 Gyr

An analysis of factors affecting project performance in industrial buildings with particular reference to design build contracts

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The problem of determining an appropriate procurement form for the management of a construction project has been surrounded by controversy and strongly held opinions. The work reported here attempts to indicate some rational basis for choice in this decision by identifying those factors which significantly affect project performance, with particular reference to the distinctions between design build and traditional procurement forms. Two basic propositions are addressed by the work. The former is that design build forms perform better than traditional forms. This view is based on the conventional, construction industry view of the factors which affect performance. The latter is that contextual factors and the management and organisation of the construction process are the major determinants of project performance. This view stems from the application of management theory to the construction process and takes into account more and diverse variables than the conventional view. The factors which affect construction project performance are identified by reviewing three basic areas which are fundamental to the research. The first is the construction process and the way it has been treated and analysed in the past, which has been based around the traditional form of organisation. The second is the perceptions held concerning the design build process and how this procurement form has developed over recent years. A taxonomy of design build organisations is presented. Finally, the literature concerning project management, in general and specifically applied to the construction process, is reviewed and those factors which have been identified as affecting project performance identified. Following on is a review of performance measures which have previously been adopted. Based on this review a number of measures are chosen to compare performance (a mixture of objective and subjective measures). The foregoing leads to the situation where two research models are proposed and tested, by the formulation of related hypotheses, in two separate phases of the research process. A sample of 47 projects was used in the initial phase of the work and this was followed up by 27 detailed case studies in the subsequent phase. The data collected are analysed using partial correlation analysis as the principal analytic tool and the main results are reported below. The primary conclusion to be drawn is that procurement form is not a good predictor of performance. In general, the management, organisation and contextual variables are found to be more strongly associated with performance. Specifically, increased client complexity and dependence are found to be associated with reduced performance, as are increased project complexity and uncertainty. Document certainty and completeness and the degree of competition in letting construction works are all factors found to affect performance. Familiarity and differentiation are organisational factors which are found to be strongly associated with performance. Finally, it is shown that different procurement forms can be located on a structure grid and that those organisations which are appropriately located are associated with higher levels of performance