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The purpose of the study was to evaluate the influence of nutrition and of the severity of mutation type on survival rate in cystic fibrosis (CF) patients. Data were longitudinally collected from 60 hospitalized adult CF patients, aged 18-50. The variables consisted of body mass index (BMI) ratio, Cole's BMI cut-off points, severity of mutation type, and survival rate of CF patients. We found that the mean BMI was strongly associated with the severity of mutation type and was significantly lower in patients with severe mutations of grade I and II. The mutation type significantly affected the patients' survival rate; survival was greater in patients with mild and undefined mutation types. The BMI and Cole's cut-off points also had a significant influence on survival rate. CF patients, who suffered from malnutrition and emaciation, had a shorter survival rate than those with proper nutritional status. In conclusion, the study findings confirmed a significant effect of nutritional status and of mutation type on survival rate of CF patients.

Low pressure membranes can be effective in treating various types of water, but are subject to fouling. In this work, chemical coagulation was studied as a pretreatment to ultrafiltration (UF), with the goal of mitigating fouling while maintaining high permeate water quality. Alum and ferric chloride were evaluated, as well as two polyaluminum chloride (PACl) products of different basicities and compositions. A bench-scale hollow fiber UF unit was developed to study the treatment of raw and pretreated water from two southern Ontario drinking water sources. The four coagulants were compared at optimal dosages, as well as at lower dosages. The roles of mixing and pH conditions were also evaluated. Membrane fouling was evaluated by observing changes in trans-membrane pressure (TMP) over 3-day experiments. Under optimal dose conditions, all four coagulants were able to reduce the rate at which the membrane fouled to varying degrees for each water source. Total organic carbon (TOC) removal by the membrane was also enhanced with coagulation pretreatment as would be expected. Experiments conducted with low coagulant dosages displayed under-dosing and a subsequent increase in membrane fouling. Experiments conducted with modified raw water pH improved both membrane performance and TOC removal, while experiments with modified mixing intensities proved ineffective.

In this paper, we present results of transmission electron microscopy studies on erbium silicide structures fabricated under various thermal conditions. A titanium cap has been used as a protective layer against oxidation during rapid thermal annealing of an erbium layer in a temperature range of 300-700°C. Both layers (200 nm Ti and 25 nm Er) were deposited by electron-beam sputtering. The investigations have shown that the transformation of the 25-nm-thick erbium into erbium silicide is completed after annealing at 500°C. At higher temperatures, the formation of a titanium silicide layer above erbium silicide is observed. The lowest Schottky barrier has been measured in the sample annealed at 700°C. © 2010 The Royal Microscopical Society.

The purpose of the study was to evaluate the influence of body size and shape, and of fat distribution on respiratory functions in adult women. The sample consisted of 107 women aged 17-82 years. Height, weight, chest, waist and hip circumferences, abdominal, and subscapular and triceps skinfolds were examined. The BMI and WHR were calculated. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF), maximal expiratory flow (MEF75), forced expiratory time (FET) were used as measures of respiratory function. Positive correlations were found between z-scores of height and VC, FEV1, FVC, between WHR and VC, and between circumference and FET. Negative correlations were found between z-scores of BMI and VC, FEV1, between subscapular skinfold and VC, FEV1, FVC and between abdominal skinfold and VC. Stepwise multiple regression analysis showed that traits of body size and shape mostly influenced VC (32 %) and FVC (31 %). Body height and WHR significantly affected VC, while height and subscapular skinfold affected FVC. A significant association between fat distribution described by BMI, WHR, and skinfold thickness and respiratory parameters was observed. These results confirm a complex effect of body size and shape, and of fat distribution on respiratory function.

The influence of enhanced hydrostatic pressure on evolution of dislocations in self-implanted silicon during annealing at different temperatures was investigated by means of electron microscopy methods. It is found that the main cause of the pressure impact differs for various annealing temperatures. The annealing under enhanced pressure at lower temperature (1070 K) has a negligible effect on structure of dislocations located in a thin layer (end-of-range (EOR) defects). At this temperature, enhanced pressure mainly increases the density of microdefects with oxygen precipitation. It is found that after high-temperature annealing (1400 K), enhanced hydrostatic pressure (HP) reduces dislocation density near the surface; however, dislocations extend deeper into the substrate as compared to the samples annealed under atmospheric pressure. The effect is attributed mainly to the reduction of silicon interstitial-atoms migration towards the surface due to increase in energy necessary to make silicon interstitial atom occupy a lattice site at the surface.

An InGaAs/GaAs quantum-dot (QD) microcavity light-emitting diode (MCLED) emitting at 1.3 μm at room temperature was analyzed. The long wavelength emission of 1.3 μm emission was achieved by using InGaAs quantum dots which were directly grown on GaAs by metallorganic chemical vapor deposition. Electroluminescence bright emission peaked at 1298 nm was exhibited by the device with full width at half maximum of 6.5 meV. The results show linear dependence of optical output power as function of injection current.

Defects in the Si layered structures, Si:H(D), prepared by implantation with H 2 + /D + , and their changes resulting from the treatment under enhanced pressure (HP), were investigated by X-ray diffraction and transmission electron microscopy (XTEM). Such treatment affects out-diffusion of hydrogen (deuterium) as well as the shape and concentration of the H(D)-filled cavities. The relation between X-ray and XTEM results is discussed.

The effect of high temperature (HT, up to 1400 K)–hydrostatic pressure (HP, up to 1.2 GPa) on Czochralski silicon implanted with hydrogen (Si:H, H dose, D H = 5 × 1 0 16 cm − 2 ), helium (Si:He, D He = 5 × 1 0 16 cm − 2 ) or helium + hydrogen (Si:He, H, total D H + He = 1 × 1 0 17 cm − 2 ) has been investigated by TEM, SIMS and PL measurements. The treatment of Si:H, Si:He and Si:He, H at ≤1070 K–HP results in a formation of buried nanostructured layers composed of hydrogen/helium filled cavities/platelets and numerous point and extended defects; much fewer dislocations are created at ≥1270 K–HP. The microstructure of Si:He, H evidences specific interaction of implanted helium and hydrogen, affecting the creation of Si–H bonds.

Czochralski-grown silicon samples subjected to high temperature–high pressure (HTHP) treatments in the range of 900 °C were irradiated with fast neutrons. Transmission electron microscopy measurements revealed the presence of oxygen precipitates (SiOx) and dislocation loops. The purpose of this work is to investigate the effect of these defects on the annealing behavior of neutron-irradiated induced oxygen-related defects, mainly the VO and the VO2 centers. To this end, infrared spectroscopy measurements were employed to monitor the conversion of the VO center (828 cm−1) to the VO2 center (890 cm−1 band) during isochronal anneals. In the untreated samples this conversion occurs around 300 °C. In our studies, we found that the annealing temperature (Tann) of the VO centers is lower than 300 °C. The value of Tann depends on the particular HTHP pretreatment. Actually, as a result of the precipitation process silicon self-interstitials (SiIs) are emitted and a number of them is bound at the Si/SiOx interface....

Electron microscopic techniques have been applied to the characterization of degraded single quantum well separate-confinement heterostructure (SQW SCH) stripe geometry lasers. Scanning electron microscopy (SEM) investigations have revealed changes at the lasers mirrors, an anomalous behavior of their junctions and a partial lack of the electron beam-induced luminescence in the active stripe areas of the devices. Cross-sectional transmission electron microscopy (XTEM) has revealed the presence of many crystallographic defects located in the active and cladding layers in the stripe area.

By means of cross-sectional transmission electron microscopy (TEM) the influence of the annealing temperature on the morphology of Au/ZrB 2 /Ag(Te) ohmic contacts to (1 0 0)-oriented tellurium-doped GaSb substrates has been investigated. Both the shape and the size of the Ag(Te) grains significantly varied with the annealing temperature. In the sample annealed at 250 °C, below the Ag(Te)/GaSb interface, dissolution pits (DPs) were formed. At the higher annealing temperatures the DP’s were not found. After annealing at 300 °C, changes in the Ag(Te) grains located close to the interface can be seen. These changes were not observed in the sample annealed at 350 °C. In all samples the annealing caused the formation of microtwins.

The purpose of this paper was to study by means of cross-sectional transmission electron microscopy (TEM) the uniformity of ceramic superlattices applied in silicon micro-electro-mechanical systems. Results of TEM investigation of TiN/NbN, TiN/CrN and CrN/NbN superlattices deposited on the (1 0 0)-oriented silicon substrate have been reported. The superlattice coatings consist of layers of equal thickness. The interfaces between these layers are smooth. No interface roughness is observed both between layers located at the bottom and at the top of the superlattice. The highest mean value of nanohardness is for TiN/CrN (21 GPa) and the lowest for TiN/NbN (14 GPa).

The broad-contact ridge waveguide technology was used to fabricate lasers from low-dimensional structures grown by molecular beam epitaxy (MBE). The laser diode structure used in the study was an AlGaAs/InGaAs separate-confinement heterostructure (SCH) with single quantum well (SQW) as the active region. The light-output-current (P-I) and current-voltage (I-V) characteristics were measured and images from a scanning electron microscope (SEM) were analysed for evaluation of the manufactured lasers. Irregularities and high leakage currents were observed in the P-I and I-V characteristics, respectively, if lasers had metallisation covering the entire ridge waveguide as usually in the lasers fabricated by this technique. However, the irregularities such as kinks and noise were reduced and the lasers showed stable operation as evidenced by far-field patterns if only the region just under the contact stripe was electrically excited. We conclude that a plasma exposure during processing steps induces a number of surface defects that can be enough to degrade the performance of the lasers.

Silicon on insulator (SOI) structures (Si / SiO2 layer / Si) were prepared by bonding the oxidised Si wafer with the hydrogen implanted one and a cleavage of the last wafer by the Smart Cut technique. Effect of high temperature and hydrostatic pressure (HT–HP) treatment at temperatures up to 1570 K and pressure up to 1.2 GPa, typically for 5 h, on the SOI structures was investigated by Transmission Electron Microscopy, X-Ray and photoluminescence measurements. The point and extended defects are created at HT–HP, especially near the SOI surface. That effect depends on the SOI preparation method and treatment conditions and is related to the hydrogen and pressure assisted oxygen outdiffusion from SiO2 to the SOI surface and bulk.

In this paper, we present a systematic study of the effect of growth parameters on the structural and optical properties of InAs quantum dot (QD) grown under Stranski-Krastanov mode by molecular beam epitaxy. The dot density is significantly reduced from 1.9x10(10) to 0.6x10(10) cm(-2) as the growth rate decreases from 0.075 to 0.019 ML/s, while the island size becomes larger. Correspondingly, the emission wavelength shifts to the longer side. By increasing the indium fraction in the InGaAs capping layer, the emission wavelength increases further. At indium fraction of 0.3, a ground state transition wavelength as long as 1.4 mum with the excited state transition wavelength of around 1.3 mum has been achieved in our dots. The optical properties of QDs with a ground state transition wavelength of 1.3 mum but with different growth techniques were compared. The QDs grown with higher rate and embedded by InGaAs have a higher intensity saturation level from excitation dependent photoluminescence measurements and a smaller intensity decrease from temperature dependent measurements. Finally, single mirror light emitting diodes with a QD embedded in InGaAs have been fabricated. The quantum efficiency at room temperature is 1.3%, corresponding to a radiative efficiency of 21.5%. (C) 2002 American Institute of Physics.

The structure of oxygen - implanted (up to a dose 6x10 17 cm -2 ) silicon, Si:O, treated at 1400 - 1550 K under high (up to 1.5 GPa) argon pressure, was investigated by numerous methods. The oxygen distribution peak narrowed, the dimensions of extended defects decreased and the peak intensity in the Si - O - Si asymmetric stretching vibrational mode diminished with pressure. That effects are explained by decreased misfit at the SiO 2-x /Si boundary and more numerous nucleation sites created in Si:O treated at high pressure.

The effect of annealing at up to 1550 K under argon pressure up to 1.5 GPa (high temperature–high pressure (HT–HP) treatment) on silicon implanted with helium, hydrogen or oxygen (Si:He, Si:H or Si:O) was investigated by X-ray, secondary ions mass spectrometry (SIMS), transmission electron microscopy (TEM), photoluminescence (PL), and electrical methods. The HT–HP treatment of Si:He results in decrease of defect concentration. The treatment at 720 K, 1.1 GPa for 10 h resulted in unchanged strain (while annealing at 720 K, 10 5 Pa – in its marked decrease) and in enhancement of thermal donor (TD) concentration. A similar treatment of Si:H resulted in suppression of hydrogen out-diffusion with its pronounced diffusion into sample depth and stress-stimulated creation of small defects/TD. Generation of dislocations was strongly suppressed in the HT–HP treated Si:O samples. The observed effects were explained accounting for HP-induced suppression of helium and hydrogen out-diffusion from Si:He and Si:H, and for a decrease of misfit at the oxygen precipitate/Si boundary in Si:O.

We discuss some problems of molecular beam technology (MBE) technology of planar microcavities based on GaAs, AlGaAs and InGaAs compounds. This technology needs specific methods of in situ control and postgrowth characterization. One of the crucial problems is that of controlling the substrate temperature and the growth rate with very high accuracy. We demonstrate the usefulness of substrate temperature oscillations observed by infrared pyrometry for both the temperature and the growth rate control. For studying the perfection of layers and interfaces the cross-sectional transmission electron microscopy has been used. To optimize the optical characteristics of the microcavities, several experimental methods have been applied. The Bragg reflectors were investigated by optical reflectivity. For selective excitation of a quantum well (QW) in a cavity active layer, the Ti-sapphire tuneable laser have been used. The fine tuning between the QW emission and the cavity Fabry–Perot resonance has been investigated by photoluminescence for varying temperature of the sample.

Selective area (SA) metalorganic vapor phase epitaxy (MOVPE) proves to be an effective method of manufacturing nonplanar structures with precisely controlled sizes and orientations of their facets. Excellent flatness of the facets makes SA MOVPE especially useful for optoelectronic applications such as microcavities. In this work we use this technique to grow prism-shaped GaAs cavities for novel prismatic (folded) cavity surface emitting laser diodes. Design of these devices has been recently proposed. Critical points in growing the cavities are: (i) to ensure 90° angle at the top of the prism, (ii) to obtain flat walls of the GaAs prism (4 μm wide at the base) with the sharp top, (iii) to avoid an excessive number of polycrystalline precipitates on the surface of a dielectric mask (SiO2 100 nm thick) despite the very disadvantageous ratio of openings to whole substrate area. Growth-rate calculations have been performed using total area of mask openings as an active substrate surface. For proper prism growth the pulsing epitaxy technique using Aixtron MOVPE LP system was applied, where interruption growth periods which enabled efficient surface molecules migration into openings. Optimization of the growth/interruption time versus partial pressure of gallium was essential for laser application to obtain suitable shape of the prisms. The best results for 2 μm high prisms were obtained for 272 pulses of 2 s growth/3 s interruption, when total pressure and temperature were 100 mbar and 700°C, respectively.

The role of blood proteinases in the mobilization of hematopoietic stem/progenitor cells (HSPCs) is still not well understood. As previously reported, activation of the complement cascade (ComC) and cleavage of C5 by C5 convertase are enabling events in the release of C5a that plays a crucial role in the egress of HSPCs from bone marrow (BM) into peripheral blood (PB) and explains why C5-deficient mice are poor mobilizers. Here we provide evidence that during granulocyte colony-stimulating factor- and AMD3100-induced mobilization, not only the ComC but also two other evolutionarily ancient proteolytic enzyme cascades, the coagulation cascade (CoaC) and the fibrynolytic cascade (FibC), become activated. Activation of all three cascades was measured by generation of C5a, decrease in prothrombin time and activated partial thromboplastin time as well as an increase in the concentrations of plasmin/antiplasmin and thrombin/antithrombin. More importantly, the CoaC and FibC, by generating thrombin and plasmin, respectively, provide C5 convertase activity, explaining why mobilization of HSPCs in C3-deficient mice, which do not generate ComC-generated C5a convertase, is not impaired. Our observations shed more light on how the CoaC and FibC modulate stem cell mobilization and may lead to the development of more efficient mobilization strategies in poor mobilizers. Furthermore, as it is known that all these cascades are activated in all the situations in which HSPCs are mobilized from BM into PB (for example, infections, tissue/organ damage or strenuous exercise) and show a circadian rhythm of activation, they must be involved in both stress-induced and circadian changes in HSPC trafficking in PB.

The concept that adult tissue, including bone marrow (BM), contains early-development cells with broader differentiation potential has again been recently challenged. In response, we would like to review the accumulated evidence from several independent laboratories that adult tissues, including BM, harbor a population of very rare stem cells that may cross germ layers in their differentiation potential. Thus, the BM stem cell compartment hierarchy needs to be revisited. These dormant, early-development cells that our group described as very small embryonic-like stem cells (VSELs) most likely overlap with similar populations of stem cells that have been identified in adult tissues by other investigators as the result of various experimental strategies and have been given various names. As reported, murine VSELs have some pluripotent stem cell characteristics. Moreover, they display several epiblast/germline markers that suggest their embryonic origin and developmental deposition in adult BM. Moreover, at the molecular level, changes in expression of parentally imprinted genes (for example, Igf2-H19) and resistance to insulin/insulin-like growth factor signaling (IIS) regulates their quiescent state in adult tissues. In several emergency situations related to organ damage, VSELs can be activated and mobilized into peripheral blood, and in appropriate animal models they contribute to tissue organ/regeneration. Interestingly, their number correlates with lifespan in mice, and they may also be involved in some malignancies. VSELs have been successfully isolated in several laboratories; however, some investigators experience problems with their isolation.

The goal of regenerative medicine is to ameliorate irreversible destruction of brain tissue by harnessing the power of stem cells in the process of neurogenesis. Several types of stem cells, including mesenchymal stem cells, hematopoietic stem cells, as well as neural cells differentiated from embryonic stem cell lines, have been proposed as potential therapeutic vehicles. In this review paper we will discuss a perspective of stem cell therapies for neurological disorders with special emphasis on potential application of cells isolated from adult tissues. In support of this our group found that murine bone marrow contains a mobile population of Oct-4+CXCR4+SSEA-1+Sca-1+lin⁻CD45⁻ very small embryonic-like stem cells (VSELs) that are mobilized into peripheral blood in a murine stroke model. The number of these cells in circulation increases also after pharmacological mobilization by administration of granulocyte colony stimulating factor (G-CSF). Recently we found that VSELs are present in various non-hematopoietic adult organs and, interestingly, our data indicate that the brain contains a high number of cells that display the VSEL phenotype. Based on our published data both in human and mice we postulate that VSELs are a mobile population of epiblast/germ line-derived stem cells and play an important role as an organ-residing reserve population of pluripotent stem cells that give rise to stem cells committed to particular organs and tissues--including neural tissue. In conclusion human VSELs could be potentially harnessed in regenerative medicine as a source of stem cells for neurogenesis.

The formation of ytterbium silicide fabricated by annealing at 480 °C for one hour has been studied by means of high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS). The annealing process has been performed under ultra high vacuum (UHV) conditions. The formation of an amorphous silicide layer was observed between the Yb-layer and the silicon substrate in the as-deposited sample. Ytterbium silicide observed after annealing consists of two different layers: crystalline and amorphous ones. The studies confirmed that the formed crystalline layer is of the YbSi phase, however, the structure is different from the hexagonal AlB type. © 2010 IOP Publishing Ltd.

Cathodoluminescence (CL) studies are widely applied in semi-conductor science and technology. However, for structures with a p-n junction the CL spatial distribution can be strongly affected by internal current flows of the electron beam induced current generated within the structure. This influence is the investigated in application to CL studies of degradation in aged laser diodes with InGaN multiquantum wells.

In the present paper we discuss possible degradation mechanisms of InGaN violet laser diodes, grown on bulk GaN substrates. Lifetime tests include electrical and optical parameters monitoring, temperature and microstructural studies. Our results point out at very strong, the exponential dependence of the degradation rate on the operation current of the device. The square root-like behavior of the degradation as a function of time is also reconfirmed. Our microstructural analysis indicates also that the appearance of strain driven defects (dislocation loops formed around AlGaN/GaN interface) may have an influence on the laser diode degradation. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The transmission electron microscopy characterization of various silicon and silicide fin structures intended for application in FinFET devices has been performed. The results showed that transmission electron microscopy is a very useful tool for optimization of manufacturing processes of fin nanostructures in FinFETs.

Bone marrow (BM) was for many years primarily envisioned as the “home organ” of hematopoietic stem cells (HSC). Augmenting evidence demonstrates, however that BM in addition to HSC also contains a heterogeneous population of non-hematopoietic stem cells (non-HSC). Recently our group identified in BM and other adult tissues a population of very small embryonic like stem cells (VSELs) which express several markers characteristic for pluripotent stem cells (PSC) that are characteristic for epiblast/germ line- derived stem cells. Thus, we hypothesize that VSELs are a population of epiblast-derived cells that are deposited during early gastrulation in developing tissues/organs and play an important role in turnover of tissue specific/committed stem cells. In this context VSELs deposited in BM may give rise to long term repopulating HSC. VSELs could be also mobilized into peripheral blood (PB) and their number of these cells circulating in PB increases during stress and tissue/organ injuries. Finally, we envision that in pathological situations VSELs are involved in development of some malignancies (e.g., teratomas, germinal tumors).

In this work we present the reliability study of InGaN violet laser diodes fabricated by metaloorganic vapor phase epitaxy on high pressure grown bulk GaN crystals. Our devices were tested both in cw and a pulse regime. We found out that the degradation rate of the laser diodes does not depend on the photon density (at least up to around 50 mW of an output optical power). We show also that the main factor influencing the degradation rate is an operation current density on which the degradation rate depends exponentially. Additionally, we reconfirm that the degradation follows the square root dependence between threshold current and time suggesting that the diffusion may be a main mechanism causing damage of diodes.

Electromagnetic interference is one of the main distortion sources in scanning electron microscopy. Electromagnetic interference-generated scanning electron microscopy image distortions are usually visible as edge blur (at low scan rates) or vibration (at high scan rates). Hardware solutions to this problem, e.g. electrostatic and magnetic shielding, are expensive and, in some cases, difficult to implement. The current investigations led to a significant decrease in the periodic distortions by a novel adaptation of software-based digital signal processing to scanning electron microscopy problems, without any hardware modification.

Very thin erbium silicide layers have been used as source and drain contacts to n-type Si in low Schottky barrier MOSFETs on silicon-on-insulator substrates. Erbium silicide is formed by a solid-state reaction between the metal and silicon during annealing. The influence of annealing temperature (450 degrees C, 525 degrees C and 600 degrees C) on the formation of an erbium silicide layer in the Pt/Er/Si/SiO(2)/Si structure was analysed by means of cross-sectional transmission electron microscopy. The Si grains/interlayer formed at the interface and the presence of Si grains within the Er-related layer constitute proof that Si reacts with Er in the presence of a Pt top layer in the temperature range 450-600 degrees C. The process of silicide formation in the Pt/Er/Si structure differs from that in the Er/Si structure. At 600 degrees C, the Pt top layer vanishes and a (Pt-Er)Si(x) system is formed.

Bone marrow (BM) contains a population of self-renewing hematopoietic stem cells (HSC) that give rise to cells from all hemato-lymphopoietic lineages. The concept that HSC could also be plastic and be able to transdifferentiate into stem/progenitor cells for different non-hematopoietic tissues became one of the most controversial issues of modern stem cell biology. Accumulating experimental evidence suggests that contribution of BM-derived stem cells to organ/tissue regeneration could be explained not by plasticity (transdifferentiation) of HSC but rather by the presence of non-hematopoietic stem cells in BM. In this review new evidence will be presented, that adult BM contains a small population of pluripotent very small embryonic-like (VSEL) stem cells. These cells are deposited in BM early during ontogenesis and could be mobilized from BM and circulate in peripheral blood during tissue/organ injury in an attempt to regenerate damaged organs. However, if these cells are mobilized at the wrong time and migrate to the wrong place they may contribute to the development of several pathologies, including tumor formation.

Detailed study of the coexistence of zinc blende and wurtzite phases in the luminescent layer and quantitative relations between phases after ageing processes of ZnS:Cu:Cl phosphors has been performed by means of cross-sectional transmission electron microscopy (XTEM). The diffraction analysis of as-fabricated phosphors revealed that in the ZnS:Cu:Cl layer only the zinc blende phase exists. However, in aged phosphors both zinc blende and wurtzite phases with the zinc blende phase dominating can be observed. Additional cathodoluminescence (CL) analysis of ZnS:Cu:Cl grains carried out in a scanning electron microscope (SEM) confirmed that the Cu-dopant influenced the luminescence properties of ZnS:Cu:Cl phosphors.

The new and earlier reported results on the effect of hydrostatic pressure (HP, up to 1.23 GPa) and annealing at ≤ 1570 K of oxygen implanted silicon (Si:O) are discussed. HP affects the misfit at the SiOx/Si boundary, solubility and diffusivity of oxygen, the number and dimensions of SiOx precipitates.

Effect of stress exerted by hydrostatic pressure (HP) of Ar, up to 1.1 GPa (HT-HP treatment) during annealing at up to 1070 K, on hydrogen storage and microstructure of Czochralski grown silicon (Cz-Si) co-implanted with hydrogen and helium (Cz-Si∶H,He, with different sequences of the H- and He-enriched areas) and of reference Cz-Si∶H was investigated.

We investigate Er silicide formed on n-type silicon. In order to protect the Er from oxidation during the formation of Er silicide in non-UHV conditions, a Pt layer is deposed successively on top of Er layer. Surprisingly, we observe that Pt remains essentially unaffected in the formation of Er silicide at temperatures lower than 700 degreesC. We find that silicidation process is fully completed by rapid thermal annealing at 500 degreesC. A simplified method of analysis considering the final Schottky barrier MOSFET application has been used to characterize the Schottky barrier of the PtEr-stack silicide system. A very low apparent Schottky barrier (smaller than 0.1 eV) on a n-type silicon substrate with a concentration of 1.4 x 10(16) cm(-3) in the active region has been obtained. (C) 2003 Elsevier Ltd. All rights reserved.

The application of cross-sectional transmission electron microscopy and scanning electron microscopy to the investigation of optoelectronic devices are reviewed. Special attention was paid to the electron microscopy assessment of the growth perfection of such crucial elements of the devices like quantum wells, quantum dots, distributed Bragg reflectors as well as electrical contacts. Using these examples, the most important issues of the application of electron microscopy to characterization of optoelectronic devices are discussed.

The effect of heat treatment (up to 1570 K) under hydrostatic argon pressure (up to 1.2 GPa) on silicon implanted with helium and oxygen was investigated by transmission electron microscopy, X-ray diffraction and related methods. The treatment results in specific stress-related changes of Si/Si:He/Si and Si/Si:O/Si structures, especially in dislocation density. Such investigations can help in understanding the effect of stress at the layer/substrate interface during epitaxial growth and thermal treatment.

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) regulate the turnover of the extracellular matrix and may modulate the biology of haematopoietic cells. We investigated whether MMPs and TIMPs are produced in long-term marrow cultures (LTMCs) established from normal donors and acute myelogenous leukaemia (AML) patients, and by fibroblast- (F), granulocyte macrophage- (GM) and megakaryocyte- (Meg) colony-forming unit (CFU) and erythroid burst-forming unit (BFU-E)-derived precursor cells. ProMMP-9 levels were highest (400 ng/ml) at week 1 of normal LTMC, whereas proMMP-2, TIMP-1, TIMP-2 and TIMP-3 levels peaked (up to 1000 ng/ml) after the establishment of the adherent layer. In LTMC from AML patients, these patterns of secretion were reversed. Moreover, we found that after a 24 h incubation in serum-free media, normal CFU-GM-, BFU-E- and CFU-Meg-derived cells secreted proMMP-9 and CFU-F-derived cells proMMP-2, in contrast to cells from LTMC adherent layer which secreted both active and latent forms of MMP-2 and MMP-9 under serum-free conditions. However, when these adherent cells were incubated in 12.5% fetal calf or horse serum or complete LTMC growth media, active forms of MMP-2 and MMP-9 were no longer detectable, and TIMP levels increased. Hence, we concluded that (i) MMPs/TIMPs are secreted by normal human bone marrow haematopoietic and stromal cells and may play an important role in intercellular cross-talk in haematopoiesis; and (ii) only latent forms of MMPs are present under LTMC conditions, indicating that the specific media used for weekly re-feeding of LTMC can block activation of MMP-2 and MMP-9, maintaining the integrity of the stromal layer and supporting haematopoiesis in vitro.

Cyclic amegakaryocytic thrombocytopenic purpura is a rare syndrome characterized by periodic failure of megakaryocytopoiesis. In this report we describe a patient with cyclic amegakaryocytic thrombocytopenic purpura associated with a megakaryocyte specific serum IgG antibody, who responded to cyclosporin A therapy. Serial serum thrombopoietin assays during an episode of platelet cycling demonstrated a reciprocal relationship between serum thrombopoietin level and megakaryocyte mass, suggesting that megakaryocytes have an important role in the regulation of thrombopoietin metabolism.

Thrombocytopenia is a late complication of human immunodeficiency virus (HIV) infection. The chemokine receptor CXCR4 has been shown to be a co-receptor for lymphocyte-tropic HIV-1 strains. CXCR4 is also a natural receptor for the chemokine SDF-1. We have previously shown that CXCR1 and CXCR2 are present on megakaryocytes and platelets. Although interleukin-8 (IL-8) and other chemokines that bind to these two receptors do not activate platelets, they are able to inhibit megakaryocytopoiesis, presumably through these receptors. We therefore examined whether CXCR4 is present on developing and mature megakaryocytes and on platelets. Reverse transcription-polymerase chain reaction (RT-PCR) demonstrated the presence of CXCR4 message. Immature and mature alphaIIbbeta3+ megakaryocytes, and platelets were also positive for CXCR4 by flow cytometric studies using a CXCR4-specific antibody. We then tested whether SDF-1 can affect the biology of these cells. CD34+ cells and immature alphaIIbbeta3+ cells responded to SDF-1 as indicated by Ca2+ mobilization and chemotaxis. However, mature megakaryocytes failed to demonstrate either of these responses, in spite of their continued ability to bind 125I-SDF-1. Further, SDF-1 failed to inhibit megakaryocyte colony growth. Platelets bound 125I-SDF-1 with a K(D) similar to the affinity seen for CXCR4 on other cells, yet SDF-1 did not aggregate washed platelets nor augment aggregation by low-dose ADP or thrombin. SDF-1 also failed to stimulate Ca2+ mobilization, granular release or expression of P-selectin in platelets. Accordingly, although our studies demonstrate that CD34+ precursors, megakaryocytes and platelets all express CXCR4 and bind SDF-1, biological effects were only demonstrable of SDF-1 on CD34+ precursors. The potential biological implications of CXCR4 expression on maturing megakaryocytes and platelets in normal individuals and following HIV infection are discussed.

The recent discovery of chemokine receptors as coreceptors for human immunodeficiency virus-type 1 (HIV-1) entry offers new avenues for investigating the pathogenesis of acquired immunodeficiency syndrome (AIDS)-related cytopenias. To this end, we sought to (1) phenotype human hematopoietic cells for CD4 and the HIV-1 coreceptors CXCR4, CCR5, CCR3, and CCR2b; (2) correlate CD4 and chemokine receptor expression with their susceptibility to HIV-1 infection; and (3) examine any potential interplay between inflammatory cytokines released during HIV-1 infection and regulation of chemokine receptor expression. Fluorescence-activated cell sorting (FACS) analysis of bone marrow mononuclear cells (BMMNC), cells derived from serum-free expanded hematopoietic lineages (colony-forming unit-granulocyte-macrophage [CFU-GM], colony-forming unit-megakaryocyte [CFU-Meg], and burst-forming unit-erythroid [BFU-E]), and CD34(+) cells showed differential expression of chemokine receptors and CD4 with some lineage specificity. Significantly, FACS-sorted CXCR4(+)/CD34(+) cells had the same clonogeneic potential as CXCR4(-)/CD34(+) cells. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of FACS-sorted human candidate stem cells (HSC; CD34(+), c-kit+, Rho123(low)) showed the presence of CXCR4 mRNA but not CD4 mRNA. Infection studies with HIV-1 Env-pseudotyped luciferase reporter viruses indicated that X4 Env (CXCR4-using) pseudotypes infected megakaryocytic cells, whereas R5 Env (CCR5-using) pseudotypes did not. Similarly, R5 but not X4 Env-pseudotyped viruses infected granulocyte-macrophage cells in a CD4/CCR5-dependent manner. Erythroid cells were resistant to R5 or X4 viral infection. Finally, we found that gamma-interferon treatment upregulated CXCR4 expression on primary hematopoietic cells. In summary, the delineation of chemokine receptor expression on primary hematopoietic cells is a first step towards dissecting the chemokine-chemokine receptor axes that may play a role in hematopoietic cell proliferation and homing. Furthermore, susceptibility of hematopoietic cells to HIV-1 infection is likely to be more complicated than the mere physical presence of CD4 and the cognate chemokine receptor. Lastly, our results suggest a potential interplay between gamma-interferon secretion and CXCR4 expression.

Vascular endothelial growth factor (VEGF) and placental derived growth factor (PlGF) stimulate cell proliferation and differentiation by binding to their specific receptors, Flk-1/KDR and Flt-1 respectively. Flk-1/KDR-deficient murine embryos manifest failure of blood-island formation and vasculogenesis. The aim of this study was to directly evaluate the importance of VEGF, PlGF/Flt-1 and Flk-1/KDR receptor ligand interactions in regulating normal and malignant human haemopoiesis. Addition of VEGF and PlGF failed to enhance survival or cloning efficiency of human haemopoietic progenitors isolated from adult bone marrows, fetal livers or cord blood samples. This finding may be explained by the apparent absence of mRNA encoding Flt-1 and Flk-1/KDR receptors on stem cell rich CD34+ c-kit-R+ Rh123(low) cells. Further studies revealed that Fit-1 R mRNA, but not Flk-1/KDR mRNA was first detectable in the more mature cells isolated from haemopoietic colonies. Accordingly, VEGF receptors are either absent, or expressed at very low level, on human haemopoietic stem/progenitor cells. Of interest, normal and malignant human haemopoietic cells appeared to secrete VEGF protein. However, in contrast to normal haemopoietic progenitors, VEGF co-stimulated HEL cell proliferation as well as CFU-GM colony formation from approximately 15% of the chronic myeloid leukaemia (CML) and acute myeloid leukaemia (AML) patients studied. Therefore, although VEGF appeared to have minimal effects on normal haemopoietic cell growth it would appear to drive malignant haemopoietic cell proliferation to some degree. Of more importance, however, we speculate that VEGF may play an very important role in leukaemogenesis by stimulating growth of vascular endothelium, thereby providing a sufficient blood supply to feed the growing haematological tumour.