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We investigate ordered nucleation of Ge islands on pit-patterned Si(001) using an original hybrid Kinetic Monte Carlo model. The method allows us to explore long time-scale evolution while using large simulation cells. We analyze the possibility to achieve selective nucleation and island homogeneity as a function of the various parameters (flux, temperature, pit period) able to influence the growth process. The presence of an optimal condition where the atomic diffusivity is sufficient to guarantee nucleation only within pits, but not so large to induce significant Ostwald ripening, is clearly demonstrated.

A structural model of carbon nanocoils (CNCs) on the basis of carbon nanotubes (CNTs) was proposed. The Young’s moduli and spring constants of CNCs were computed and compared with those of CNTs. Upon elongation and compression, CNCs exhibit superelastic properties that are manifested by the nearly invariant average bond lengths and the large maximum elastic strain limit. Analysis of bond angle distributions shows that the three-dimensional spiral structures of CNCs mainly account for their unique superelasticity.

Good-quality (11−22) semipolar GaN sample was obtained using epitaxial lateral overgrowth. The growth conditions were chosen to enhance the growth rate along the [0001] inclined direction. Thus, the coalescence boundaries stop the propagation of basal stacking faults. The faults filtering and the improvement of the crystalline quality were attested by transmission electron microscopy and low temperature photoluminescence. The temperature dependence of the luminescence polarization under normal incidence was also studied.

We investigate the current-voltage relationship and the temperature-dependent conductance of nano-scale samples of poly(dA)-poly(dT) DNA molecules. A polaron hopping model has been used to calculate the I-V characteristic of nano-scale samples of DNA. This model agrees with the data for current versus voltage at temperatures greater than 100 K. The quantities G(0), i(0), and T(1d) are determined empirically, and the conductivity is estimated for samples of poly(dA)-poly(dT).

Summary The histone deacetylase inhibitors (HDACi) have demonstrated anticancer efficacy across a range of malignancies, most impressively in the hematological cancers. It is uncertain whether this clinical efficacy is attributable predominantly to their ability to induce apoptosis and differentiation in the cancer cell, or to their ability to prime the cell to other pro-death stimuli such as those from the immune system. HDACi-induced apoptosis occurs through altered expression of genes encoding proteins in both intrinsic and extrinsic apoptotic pathways; through effects on the proteasome/aggresome systems; through the production of reactive oxygen species, possibly by directly inducing DNA damage; and through alterations in the tumor microenvironment. In addition HDACi increase the immunogenicity of tumor cells and modulate cytokine signaling and potentially T-cell polarization in ways that may contribute the anti-cancer effect in vivo. Here, we provide an overview of current thinking on the mechanisms of HDACi activity, with attention given to the hematological malignancies as well as scientific observations arising from the clinical trials. We also focus on the immune effects of these agents.

Summary HDAC inhibitors (HDACI) are now emerging as one of the most promising new classes of drugs for the treatment of select forms of non-Hodgkin’s lymphoma (NHL). They are particularly active in T-cell lymphomas, possibly hodgkin’s lymphoma and indolent B cell lymphomas. Presently, two of these agents, vorinostat and romidepsin, have been approved in the US for the treatment of relapsed and refractory cutaneous T cell lymphomas (CTCL). Initially, these agents were developed with the idea that they affected transcriptional activation and thus gene expression, by modulating chromatin condensation and decondensation. It is now clear that their effects go beyond chromatin and by affecting the acetylation status of histones and other intra-cellular proteins, they modify gene expression and cellular function via multiple pathways. Gene expression profiles and functional genetic analysis has led to further understanding of the various molecular pathways that are affected by these agents including cell cycle regulation, pathways of cellular proliferation, apoptosis and angiogenesis all important in lymphomagenesis. There is also increasing data to support the effects of these agents on T cell receptor and immune function which may explain the high level of activity of these agents in T cell lymphomas and hodgkin’s lymphoma. There is ample evidence of epigenetic dysregulation in lymphomas which may underlie the mechanisms of action of these agents but how these agents work is still not clear. Current HDAC inhibitors can be divided into at least four classes based on their chemical structure. At present several of these HDAC inhibitors are in clinical trials both as single agents and in combination with chemotherapy or other biological agents. They are easy to administer and are generally well tolerated with minimal side effects. Different dosing levels and schedules and the use of isospecific HDAC inhibitors are some of the strategies that are being employed to increase the therapeutic effect of these agents in the treatment of lymphomas. There may also be class differences that translate into specific activity against different lymphoma. HDAC inhibitors will likely be incorporated into combinations of targeted therapies both in the upfront and relapsed setting for lymphomas.

Here, we study the resonant photonic states of photonic double quantum well (PDQW) heterostructures composed of two different photonic crystals. The heterostructure is denoted as B/A/B/A/B, where photonic crystals A and B act as photonic wells and barriers, respectively. The resulting band structure causes photons to become confined within the wells, where they occupy discrete quantized states. We have obtained an expression for the transmission coefficient of the PDQW heterostructure using the transfer matrix method and have found that resonant states exist within the photonic wells. These resonant states occur in split pairs, due to a coupling between degenerate states shared by each of the photonic wells. It is observed that when the resonance energy lies at a bound photonic state and the two photonic quantum wells are far away from each other, resonant states appear in the transmission spectrum of the PDQW as single peaks. However, when the wells are brought closer together, coupling between bound photonic states causes an energy-splitting effect, and the transmitted states each have two peaks. Essentially, this means that the system can be switched between single and double transparent states. We have also observed that the total number of resonant states can be controlled by varying the width of the photonic wells, and the quality factor of transmitted peaks can be drastically improved by increasing the thickness of the outer photonic barriers. It is anticipated that the resonant states described here can be used to develop new types of photonic-switching devices, optical filters, and other optoelectronic devices.

Current research efforts in biosensor design attempt to integrate biochemical assays with semiconductor substrates and microfluidic assemblies to realize fully integrated lab-on-chip devices. The DNA biotransistor (BioFET) is an example of such a device. The process of chemical modification of the FET and attachment of linker and probe molecules is a statistical process that can result in variations in the sensed signal between different BioFET cells in an array. In order to quantify these and other variations and assess their importance in the design, complete physical simulation of the device is necessary. Here, we perform a mean-field finite-element modelling of a short channel, two-dimensional BioFET device. We compare the results of this model with one-dimensional calculation results to show important differences, illustrating the importance of the molecular structure, placement and conformation of DNA in determining the output signal.

The formation of nanometer-scale islands is an important issue for bottom-up-based schemes in novel electronic, optoelectronic and magnetoelectronic devices technology. In this work, we present a detailed atomic force microscopy analysis of Si island arrays grown by molecular beam epitaxy. Recent reports have shown that self-assembled distributions of fourfold pyramid-like islands develop in 5-nm thick Si layers grown at substrate temperatures of 650 and 750°C on HF-prepared Si(001) substrates. Looking for wielding control and understanding the phenomena involved in this surface nanostructuring, we develop and apply a formalism that allows for processing large area AFM topographic images in a shot, obtaining surface orientation maps with specific information on facets population. The procedure reveals some noticeable features of these Si island arrays, e.g. a clear anisotropy of the in-plane local slope distributions. Total island volume analysis also indicates mass transport from the substrate surface to the 3D islands, a process presumably related to the presence of trenches around some of the pyramids. Results are discussed within the framework of similar island arrays in homoepitaxial and heteroepitaxial semiconductor systems.

We report the observation of coupling of single InGaAs quantum dots with the surface plasmon resonance of a metal nanocrystal, which leads to clear enhancement of the photoluminescence in the spectral region of the surface plasmon resonance of the metal structures. Sharp emission lines, typical for single quantum dot emission, are observed, whereas for reference samples, only weak continuous background emission is visible. The composite metal–semiconductor structure is prepared by molecular beam epitaxy utilizing the principle of strain-driven adatom migration for the positioning of the metal nanocrystals with respect to the quantum dots without use of any additional processing steps.

Summary Imbalances of histone acetyltransferase (HAT) and deacetylase activity (DAC) that result in deregulated gene expression are commonly observed in leukemias. These alterations provide the basis for novel therapeutic approaches that target the epigenetic mechanisms implicated in leukemogenesis. As the acetylation status of histones has been linked to transcriptional regulation of genes involved particularly in differentiation and apoptosis, DAC inhibitors (DACi) have attracted considerable attention for treatment of hematologic malignancies. DACi encompass a structurally diverse family of compounds that are being explored as single agents as well as in combination with chemotherapeutic drugs, small molecule inhibitors of signaling pathways and hypomethylating agents. While DACi have shown clear evidence of activity in acute myeloid leukemia, myelodysplastic syndromes and lymphoid malignancies, their precise role in treatment of these different entities remain to be elucidated. Successful development of these compounds as elements of novel targeted treatment strategies for leukemia will require that clinical studies be performed in conjunction with translational research including efforts to identify predictive biomarkers.

Summary Myeloproliferative neoplasms (MPN) are clonal haemopoietic progenitor cell disorders characterized by the proliferation of one or more of the haemopoietic lineages (myeloid, erythroid and/or megakaryocytic). The MPNs include eight haematological disorders: chronic myelogenous leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF), systemic mastocytosis (SM), chronic eosinophilic leukemia, not otherwise specified (CEL, NOS), chronic neutrophilic leukemia (CNL), and unclassifiable MPN (MPN, U). Therapeutic interventions for MPNs include the use of tyrosine kinase inhibitors (TKIs) for BCR-ABL1+ CML and JAK2 inhibitors for PV, ET and PMF. Histone deacetylase inhibitors (HDACi) are a novel class of drugs capable of altering the acetylation status of both histone and non-histone proteins, thereby affecting a repertoire of cellular functions in neoplastic cells including proliferation, differentiation, immune responses, angiogenesis and survival. Preliminary studies indicate that HDACi when used in combination with tyrosine kinase or JAK2 inhibitors may overcome resistance to the latter agents and enhance the pro-apoptotic effects on MPN cells. This review provides a review of pre-clinical and clinical studies that have explored the use of HDACi as potential therapeutics for MPNs.

In this work, the absorption coefficient of a metallic photonic crystal doped with nanoparticles has been obtained using numerical simulation techniques. The effects of quantum interference and the concentration of doped particles on the absorption coefficient of the system have been investigated. The nanoparticles have been considered as semiconductor quantum dots which behave as a four-level quantum system and are driven by a single coherent laser field. The results show that changing the position of the photonic band gap about the resonant energy of the two lower levels directly affects the decay rate, and the system can be switched between transparent and opaque states if the probe laser field is tuned to the resonance frequency. These results provide an application for metallic nanostructures in the fabrication of new optical switches and photonic devices.

For randomly nucleated SiGe/Si(001) islands, a significantly stronger blue-shift of the PL spectra as a function of the excitation intensity is observed when compared to islands grown on patterned substrates side by side within the same run in a solid source molecular beam epitaxy chamber. We ascribe this different PL behavior to the much larger inhomogeneity of the Ge distribution in islands on planar substrates when compared to islands grown on pit-patterned ones, as observed previously. 3D band-structure calculations show that Ge-rich inclusions of approximately 5 nm diameter at the apex of the islands can account for the observed differences in the PL spectra. The existence of such inclusions can be regarded as a quantum dot in an island and is in agreement with recent nano-tomography experiments.

We propose a self-assembling procedure for the fabrication of GaAs islands by Droplet Epitaxy on silicon substrate. Controlling substrate temperature and amount of supplied gallium is possible to tune the base size of the islands from 70 up to 250 nm and the density from 107 to 109 cm−2. The islands show a standard deviation of base size distribution below 10% and their shape evolves changing the aspect ratio from 0.3 to 0.5 as size increases. Due to their characteristics, these islands are suitable to be used as local artificial substrates for the integration of III–V quantum nanostructures directly on silicon substrate.

[ES] El 26 de junio de 2000, durante la presentación del primer borrador del Proyecto Genoma Humano, el entonces presidente de los Estados Unidos, Bill Clinton, afirmó que "hoy estamos aprendiendo el lenguaje en el que Dios creó la vida". Detrás de sus palabras se escondía una historia de más de medio siglo basada en el entendimiento del ADN como información. Mi artículo analiza esta historia, abordando los orígenes de la visión informacional de nuestros genes a principios de los 50, cómo esta visión afectó las investigaciones en el código genético (años 50 y 60) y la transformación de la idea de información genética en el contexto de las primeras técnicas de secuenciación de ADN y de la bioinformática (años 80 y 90). Propongo que el concepto de ADN como información alcanzó un climax con el planteamiento del Proyecto Genoma Humano, pero actualmente afronta una crisis que coincide con el cuestionamiento de la idea de sociedad de la información. Finalmente, analizo el desarrollo de la biología de sistemas como paradigma alternativo., [EN] On 26 June 2000, during the presentation of the Human Genome Project’s first draft, Bill Clinton, then President of the United States, claimed that “today we are learning the language in which God created life”.1 Behind his remarks lay a story of more than half a century involving the understanding of DNA as information. This paper analyses that story, discussing the origins of the informational view of our genes during the early 1950s, how such a view affected the research on the genetic code (1950s and ‘60s) and the transformation of the information idea in the context of DNA sequencing and bioinformatics (‘80s and ‘90s). I suggest that the concept of DNA as information reached a climax with the proposal of the Human Genome Project (HGP), but is currently facing a crisis coinciding with the questioning of the information society. Finally, I discuss the emergence of systems biology as an alternative paradigm., This research was conducted while holding postgraduate fellowships given by Caja Madrid Foundation, Madrid City Hall and Residencia de Estudiantes (Spain) as well as a Hans Rausing Fellowship given by the Centre for the History of Science, Imperial College, London. Without them, it would not have been feasible.

Biotechnology and genomic innovation are seen as increasingly important for achieving public health goals in Africa. In particular, vaccines based on advances in genomic technology are deemed vital in the fight against HIV/AIDS. Public-Private Partnerships (PPPs) provide a collaborative mechanism to ensure these vaccines are developed when the private sector lacks incentives to develop these products. These partnerships provide new mechanisms for transferring the knowledge required to ensure vaccine development occurs as quickly and efficiently as possible. One such accine partnership is the South African AIDS Vaccine Initiative (SAAVI). This has been successful in ensuring 'value added' (benefit gained by taking part) is created for those involved particularly in the area of intangible value added determinants of collaboration and knowledge capacity. This paper outlines the results of a case study of SAAVI and argues that it provides evidence of a need to strengthen our understanding of the linkage between wider conceptual 'systems' of innovation and health. In particular, it espouses the usefulness of 'Systems of Innovation' thinking as a means to ensure that more specific focus is placed on process outputs such as collaboration and knowledge capacity. This will ensure that necessary knowledge flow is transferred between those working in the vaccine project for more efficient and effective operations. The research also raises questions about the possibility of such case studies highlighting areas of attention that need addressing if greater linkage is to occur between innovation and health at a wider health research policy level.

This year, Italy hosted the VIII ESPS-NIS workshop. It was organized by the L-NESS Inter-University Laboratory (Politecnico di Milano and Universita di Milano Bicocca) in Como (Italy) under the auspices of Prof. Leo Miglio. The program of 10 invited speakers, 30 contributed and numerous posters covered a wide range of topics, all connected with the study of substrate patterning and high index substrate influence on the growth and the control of semiconductor nanostructures. Presentation was given on novel patterning techniques, both top-down and bottom-up, and the effect of patterning on self-organized dots and wires. In particular, wires have recently attracted a wide attention, since they are important both in fundamental physics and in advanced electronics and photonics applications. New concept bottom-up patterning techniques, like metallic droplet nano-drilling and droplet epitaxy local artificial substrates, were presented. Epitaxy of graphene on patterned substrates was also a topic of the workshop. The possibility of controlling, by substrate patterning, the nucleation site and the strain relaxation of self-organized Stranski–Krastanow dots in Ge/Si and InAs/GaAs systems has motivated a strong effort as evidenced by the number and the quality of the contribution presented. Some very interesting features involve strain engineering, position and size control, defectivity reduction. In addition, patterned substrates epitaxy inevitably involves growth on high index planes, which stimulated the understanding the effects of epitaxial growth of semiconductors on non-(100) surfaces. The ESPS-NIS meeting discussed all these aspects, which include material growth, characterization, theory and device topics related to patterned substrates, novel index substrates and low dimensional structures. Once more the meeting achieved its aim of being a forum for lively discussion of up to date work, allowing the interaction of specialist of different fields of semiconductor science and technology put together by the common interest in the effects of patterning and surface orientation on nanostructure fabrication. The vast potential of interrelation of nanotechnology, patterning and surface science was highlighted. The organizing committee would like to thank the speakers for their considerable efforts in making this workshop a success. A fundamental role in the organization was also played by the personnel of the the Centro di Cultura Scientifica Alessandro Volta of Como. Finally, special thanks are due to the University of Milano Bicocca and the Politecnico di Milano, Polo di Como whose sponsorship made this international workshop possible. ESPS-NIS VIII Conference Chair: Prof. Leo Miglio (University of Milano Bicocca) Program committee: Chair: Prof. Stefano Sanguinetti (University of Milano Bicocca) Dr Francesco Montalenti (University of Milano Bicocca) Dr Roman Sordan (Politecnico di Milano) Dr Daniel Chrastina (Politecnico di Milano) Local organizing Committee Dr Giovanni Isella (Politecnico di Milano) Dr Emiliano Bonera (University of Milano Bicocca) Dr Monica Bollani (CNR—Milano) Dr Alessandra Cazzaniga (Centro Volta)

By considering a first-order variation in electroaccepting and electrodonating powers, ω ±, induced by a change from gas to aqueous solution phase, the solvent effect on ω ± for charged ions is examined. The expression of electroaccepting and electrodonating powers in the solution phase, ω ± s, is obtained through establishing the quantitative relationship between the change of the ω ± due to the solvation and the hydration free energy. It is shown that cations are poorer electron acceptors and anions are poorer electron donors in solution compared to those in gas phase. We have proven that the scaled aqueous electroaccepting power, ω + s, of cations can act as a good descriptor of the reduction reaction, which is expected to be applied in the design of solution reactions.