Effects caused by glutamic acid and hydrogen peroxide on the morphology of hydroxyapatite, calcium hydrogen phosphate, and calcium pyrophosphate

Reacting hydroxyapatite with H2O2 vapor at 10°C and brushite CaHPO4 · 2H2O with 90% H2O2 solution at 0°C (the hydroxyapatite and brushite were both prepared in the presence of glutamic acid) yielded the relevant peroxo solvates containing up to 18% hydrogen peroxide. The peroxo compounds and their degradation products obtained at 170–960°C were morphologically studied (using SEM). The factors influencing particle sizes are considered

Synthesis of inorganic dyes based on plasmonic silver nanoparticles for the visible and infrared regions of the spectrum

The effect of various technological factors during the multistage synthesis of plasmonic silver particles in aqueous solutions on nanoparticle size, morphology, and color is studied. The synthesized suspensions are found to contain tabular silver nanoparticles of hexagonal and triangular shape. The foundations of the technology for synthesizing stable silver colloids with a high silver concentration for the visible and nearinfrared regions of the spectrum are developed

Methyltrimethoxysilane-based elastic aerogels: effects of the supercritical medium on structure-sensitive properties

Effects caused by the type of solvent used for supercritical drying on the properties of methyltrimethoxysilane-based aerogels were studied. All of the aerogel samples studied were found to be hydrophobic and to efficiently adsorb nonpolar organic compounds

Silver-doped Calcium Phosphate bone cements with antibacterial properties

Calcium phosphate bone cements (CPCs) with antibacterial properties are demanded for clinical applications. In this study, we demonstrated the use of a relatively simple processing route based on preparation of silver-doped CPCs (CPCs-Ag) through the preparation of solid dispersed active powder phase. Real-time monitoring of structural transformations and kinetics of several CPCs-Ag formulations (Ag = 0 wt %, 0.6 wt % and 1.0 wt %) was performed by the Energy Dispersive X-ray Diffraction technique. The partial conversion of β-tricalcium phosphate (TCP) phase into the dicalcium phosphate dihydrate (DCPD) took place in all the investigated cement systems. In the pristine cement powders, Ag in its metallic form was found, whereas for CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt % cements, CaAg(PO₃)₃ was detected and Ag (met.) was no longer present. The CPC-Ag 0 wt % cement exhibited a compressive strength of 6.5 ± 1.0 MPa, whereas for the doped cements (CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt %) the reduced values of the compressive strength 4.0 ± 1.0 and 1.5 ± 1.0 MPa, respectively, were detected. Silver-ion release from CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt % cements, measured by the Atomic Emission Spectroscopy, corresponds to the average values of 25 µg/L and 43 µg/L, respectively, rising a plateau after 15 days. The results of the antibacterial test proved the inhibitory effect towards pathogenic Escherichia coli for both CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt % cements, better performances being observed for the cement with a higher Ag-content

New insights into polymer mediated formation of anatase mesocrystals

The reaction between (NH4)2TiF6 and H3BO3 in the presence of varying quantities of PEG-6000 was used to form NH4TiOF3 mesocrystals (MCs). The amount of PEG-6000, employed as a template, is crucial to the formation of defect free, non-agglomerated NH4TiOF3 MCs; high concentrations lead to MC agglomeration, lower ones result in centralized defects. This polymer-mediated formation process may be understood using an analogy with known polymerization reactions. The oxofluorotitanate MCs readily undergo a thermal topotactic transformation to give anatase MCs with photocatalytic activity. The TiO2 MCs are porous, with highly orientated lamellar crystallites that form part of the larger mesocrystal structure

ГИДРОТЕРМАЛЬНО-МИКРОВОЛНОВОЙ СИНТЕЗ НАНОКРИСТАЛЛИЧЕСКОГО MnO2 В ПРИСУТСТВИИ ГЕКСАМЕТИЛЕНТЕТРАМИНА

The article considers a non-conventional approach to the synthesis of various polymorphic modifications of manganese dioxide. The approach consists in hydrothermal microwave processing of a reaction mixture containing potassium permanganate and hexamethylenetetramine. We emphasize the relevance of the work due to such MnO2 properties as catalytic and photocatalytic activity, its application in accumulators, supercondensers and biochemistry. We report on the first detailed study on the role of temperature, synthesis duration and pH value on the phase composition and morphology of nanocrystalline MnO2. We show that the phase composition of manganese dioxide is largely determined not only by temperature, synthesis duration and pH value, but also by the acid added to the reaction mixture (nitric or sulphuric). In particular, the presence of sulfuric acid apparently results in α-MnO2 stabilization. It is noted that the type of the acid used in the course of the synthesis, as well as other synthesis conditions exercise no significant influence neither on the shape nor on the size of α-, γ- and δ-MnO2 particles. In contrast, the morphology of β-MnO2 turned out to be extremely sensitive to the synthesis conditions. Long (24 h) hydrothermal processing of reaction mixtures at рН 0.5-1 results in the formation of single-phase pyrolusite. The microstructure of the latter is determined by the reaction mixture composition.В статье рассмотрен нетрадиционный подход к синтезу различных полиморфных модификаций диоксида марганца, заключающийся в гидротермально-микроволновой обработке реакционной смеси, содержащей перманганат калия и гексаметилентетрамин. Подчеркнута актуальность работы, обусловленная такими свойствами MnO2, как каталитическая и фотокаталитическая активность, его применением в аккумуляторах, суперконденсаторах, в биохимических приложениях. Подробно проанализировано влияние температуры и продолжительности гидротермально-микроволновой обработки, pH среды и типа добавляемой кислоты на фазовый состав и морфологию диоксида марганца. Показано, что фазовый состав диоксида марганца в значительной степени определяется не только температурой, продолжительностью синтеза и pH среды, но и типом добавляемой в реакционную смесь кислоты - азотной или серной. В частности, присутствие серной кислоты, по-видимому, приводит к стабилизации α-MnO2. Отмечено, что тип используемой в ходе синтеза кислоты, а также другие условия синтеза не оказывают существенного влияния ни на форму, ни на размер частиц α-, γ- и δ-MnO2. Напротив, морфология β-MnO2 оказалась крайне чувствительной к условиям синтеза: в условиях продолжительной (24 ч) гидротермальной обработки реакционных смесей в диапазоне рН 0.5-1 происходит формирование однофазного пиролюзита, микроструктура которого определяется составом реакционной смеси

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

Preimaginal Stages of the Emerald Ash Borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae): An Invasive Pest on Ash Trees (Fraxinus)

This study provides the most detailed description of the immature stages of Agrilus planipennis Fairmaire to date and illustrates suites of larval characters useful in distinguishing among Agrilus Curtis species and instars. Immature stages of eight species of Agrilus were examined and imaged using light and scanning electron microscopy. For A. planipennis all preimaginal stages (egg, instars I-IV, prepupa and pupa) were described. A combination of 14 character states were identified that serve to identify larvae of A. planipennis. Our results support the segregation of Agrilus larvae into two informal assemblages based on characters of the mouthparts, prothorax, and abdomen: the A. viridis and A. ater assemblages, with A. planipennis being more similar to the former. Additional evidence is provided in favor of excluding A. planipennis from the subgenus Uragrilus