Analysis of acoustic emission during the melting of embedded indium particles in an aluminum matrix: a study of plastic strain accommodation during phase transformation

Acoustic emission is used here to study melting and solidification of embedded indium particles in the size range of 0.2 to 3 um in diameter and to show that dislocation generation occurs in the aluminum matrix to accommodate a 2.5% volume change. The volume averaged acoustic energy produced by indium particle melting is similar to that reported for bainite formation upon continuous cooling. A mechanism of prismatic loop generation is proposed to accommodate the volume change and an upper limit to the geometrically necessary increase in dislocation density is calculated as 4.1 x 10^9 cm^-2 for the Al-17In alloy. Thermomechanical processing is also used to change the size and distribution of the indium particles within the aluminum matrix. Dislocation generation with accompanied acoustic emission occurs when the melting indium particles are associated with grain boundaries or upon solidification where the solid-liquid interfaces act as free surfaces to facilitate dislocation generation. Acoustic emission is not observed for indium particles that require super heating and exhibit elevated melting temperatures. The acoustic emission work corroborates previously proposed relaxation mechanisms from prior internal friction studies and that the superheat observed for melting of these micron-sized particles is a result of matrix constraint.Comment: Presented at "Atomistic Effects in Migrating Interphase Interfaces - Recent Progress and Future Study" TMS 201

Bioimprint aided cell recognition and depletion of human leukemic HL60 cells from peripheral blood

We report a large scale preparation of bioimprints of layers of cultured human leukemic HL60 cells which can perform cell shape and size recognition from a mixture with peripheral blood mononuclear cells (PBMCs). We demonstrate that the bioimprint-cell attraction combined with surface modification and flow rate control allows depletion of the HL60 cells from peripheral blood which can be used for development of alternative therapies of acute myeloid leukaemia (AML).AML is a clonal malignant proliferation of transformed, bone-marrow derived myeloid precursors. The disease is characterised by the rapid proliferation of the neoplastic cells (myeloblasts) resulting in failure of normal haematopoiesis with consequential bone marrow failure rapidly resulting in death if untreated.1–3 In the UK, overall survival is 16% 5 years from diagnosis. The prognosis is significantly worse in the elderly which is especially relevant as the majority of patients present over the age of 60 years.1,4–7 Therapy relies on 2–3 cycles of myeloablative chemotherapy followed by allogeneic stem cell transplants for a relatively small number of fit patients with poor prognostic features.8,9 This is accompanied by significant discomfort, and long therapy for AML is also associated with prolonged inpatient stays, considerable morbidity related to anaemia, sepsis and bleeding with an attributable mortality of 5–10%. The majority of patients relapse following induction of chemotherapy for AML and subsequent therapy is associated with a low probability of cure. Outcomes for AML patients have improved marginally over the past few decades, largely due to improvements in supportive care rather than dramatic improvements in the chemotherapeutic regimen's efficacy.10Bioimprinting is a promising area of materials chemistry aimed at mimicking and exploiting the lock-and-key interactions seen ubiquitously in nature.11–14 Cell recognition systems are relatively cheap and simple to produce with few stipulations on storage and shelf life when compared with biological interventions. The scope for possible targets is also much greater, being able to target polysaccharides, enzymes, aptamers, DNA sequences, antibodies and whole cells.12,15,16,21–24 Bioimprints of whole cells were first reported by Dickert et al.17 who imprinted yeast into a sol–gel matrix. When incubated with several strains of yeast, the substrates showed a high affinity to the template yeast strain. This effect was attributed to the large contact surface areas between the cells and the imprinted cavities. Other cell bioimprinting studies have progressed to cover a range of micro-organisms and human cells. Hayden et al.18 functionalised polyurethane with erythrocyte imprints, capable of discriminating between ABO blood groups. Though all cell targets possessed the same geometrical shape and size, imprints were able to discriminate on account of varied surface antigen expression. Subsequent studies were further able to discriminate cells with identical antibodies in different quantities to separate blood groups A1 and A2.19 Recent cell bioimprint studies largely focus on biosensor applications20,26 and are hindered by the small overall size of imprinted areas that can be produced which limits their applications for large scale extraction of targeted cells from cell mixtures. This research area is undergoing a rapid expansion towards using molecularly imprinted polymers as receptor mimics for selective cell recognition and sensing, and a recent review of size and shape targeting of cancer found no evidence so far of the use of cancer cell bioimprints in a therapeutic setting.11Here we utilised for the first time AML cell bioimprints on a large scale as a vehicle to selectively target myeloblasts due to the inherent size and morphological discrepancies compared to normal peripheral blood mononuclear cells (PBMCs) (see Fig. S1, ESI†). We explore AML cells bioimprinting to develop a new method for depletion of myeloblasts from peripheral blood cells by introducing selectivity via bespoke cell size and shape discrimination aided by myeloblast-bioimprint interactions. Our idea is based on incorporating AML cells-imprinted substrates into a flow-through type of device which offers an alternative method for removal of the leukemic burden directly from patient blood. Successful leukophoresis can potentially be used more frequently in the extraction of myeloblasts from peripheral blood which is critical in stabilizing AML patients with leukostasis associated with hyperleuocytosis. By reducing the number of circulating tumour cells, the likelihood of early relapse is also diminished.25HL60 is an immortalized human cell line derived from peripheral blood lymphocytes of a patient suffering from acute promyleocytic leukaemia. HL60 was used as a very good proxy for primary (patient derived) myeloblast cells throughout our study due to their availability and ease of culture. Here we show how the desired HL60 cell bioimprints were produced from HL60 cell layers. We also discuss the integration of the produced myeloblast imprint in a PDMS-based flow-through cell, in which its selectivity towards HL60 cells over PBMCs is investigated (Fig. 1). We fabricated bioimprints by impressing a layer of cultured HL60 cells with a curable polymer, which captures information on the cell shape, size and morphology. These were further casted with another polymer to create a “positive imprint” whose surface matches the original cell layer. Using roll-to-roll printing from the positive replica we produced a very large area of HL60 cell imprints. We engineered the surface of the bioimprint to have a weak attraction with the cells, which is strongly amplified when there is a shape and size match between the individual cells and the imprinted surface. Due to inherent size and morphology differences between myeloblasts and normal blood cells, this resulted in much higher retention of the former on the bioimprint. This allows their selective trapping from peripheral blood based on cell shape and size recognition, much cheaper than using surface functionalisation with a combination of specific antibodies for myeloblasts. We tested the bioimprints selectivity in a device for depleting cultured HL60 cells from healthy white blood cells. This cell recognition technology can potentially deplete myeloblasts from the blood of AML patients and provide an alternative route for inducing minimal residual disease, which is associated with reduced relapses and improved patient outcomes

Managing organizational DSS development in small manufacturing enterprise

A number of Hong Kong manufacturing companies have moved their production to the People's Republic of China while retaining their supporting functions (such as marketing, distribution, etc.) in Hong Kong. As a consequence, their mode of operation has become more complex and demands better production planning and control (PPC). One solution is to use an information system in which all factory resources are integrated within a single framework for PPC. The main instrument of this strategy is an Organizational DSS (ODSS). This paper presents a case study of development and adoption of an ODSS in a small manufacturing enterprise. Analysis of the findings highlights the cultural as well as organizational underpinnings and the need for effective intervention before and throughout the computerization. The implementation strategies are described, with emphasis on prerequisite infrastructural developments, showing how they provide opportunities and constraints

Targeted removal of blood cancer cells from mixed cell populations by cell recognition with matching particle imprints

We report a new approach for separation of blood cancer cells from healthy white blood cells based on cell recognition by surface functionalised particle imprints. We prepared polymeric particle imprints from a layer of suspension of monodisperse PMMA microbeads which closely match the size of in vitro cultured human leukaemia cells (HL60). The imprints were replicated on a large scale with UV curable polyurethane resin using nanoimprinting lithography and surface functionalized with a cationic polymer, a branched polyethylene imine (bPEI), and a Pluronic surfactant, Poloxamer 407, to engineer a weak attraction towards the cells. The latter is amplified several orders of magnitude when a cell of a closely matching size and shape fits into the imprint cavity which multiplies the contact area between the cell surface and the imprint. The particle imprints were optimised for their specificity toward blood cancer cells by treatment with oxygen plasma and then subsequent coatings with bPEI and Poloxamer 407 with various functionalisation concentrations. We tested the surface functionalised imprints for their specificity in retaining in vitro cultured human leukaemic cells (HL60) over healthy human peripheral blood mononuclear cells (PBMCs) in a flow through chamber. The effect of the flushing flow rate of the mixed cell suspension over the particle imprint and the imprint length were also investigated. At each step the selectivity towards HL60 was assessed. Selective isolation of an increased amount of HL60 tumour cells over PBMC was ultimately achieved as a function of the cell seeding ratio on the particle imprint. The effect is attributed to the substantial size difference between the HL60 cell and the PBMCs. The data presented show that relatively inexpensive PMMA microbeads imprints can be utilised as a cell separation technique which could ultimately lead to novel therapies for removal of neoplastic cells from the peripheral blood of acute myeloid leukaemia patients

Three heavy jet events at hadron colliders as a sensitive probe of the Higgs sector

Assuming that a non-standard neutral Higgs with an enhanced Yukawa coupling to a bottom quark is observed at future hadron experiments, we propose a method for a better understanding of the Higgs sector. Our procedure is based on "counting" the number of events with heavy jets (where "heavy" stands for a c or b jet) versus b jets, in the final state of processes in which the Higgs is produced in association with a single high p_T c or b jet. We show that an observed signal of the type proposed, at either the Tevatron or the LHC, will rule out the popular two Higgs doublet model of type II as well as its supersymmetric version - the Minimal Supersymmetric Standard Model (MSSM), and may provide new evidence in favor of some more exotic multi Higgs scenarios. As an example, we show that in a version of a two Higgs doublet model which naturally accounts for the large mass of the top quark, our signal can be easily detected at the LHC within that framework. We also find that such a signal may be observable at the upgraded Tevatron RunIII, if the neutral Higgs in this model has a mass around 100 GeV and \tan\beta > 50 and if the efficiency for distinguishing a c jet from a light jet will reach the level of 50%.Comment: Revtex, 11 pages, 4 figures embedded in the text. Main changes with respect to Version 1: Numerical results re-calculated using the CTEQ5L pdf, improved discussion on the experimental consequences, new references added. Conclusions remain unchanged. As will appear in Phys. Rev.

Investment under ambiguity with the best and worst in mind

Recent literature on optimal investment has stressed the difference between the impact of risk and the impact of ambiguity - also called Knightian uncertainty - on investors' decisions. In this paper, we show that a decision maker's attitude towards ambiguity is similarly crucial for investment decisions. We capture the investor's individual ambiguity attitude by applying alpha-MEU preferences to a standard investment problem. We show that the presence of ambiguity often leads to an increase in the subjective project value, and entrepreneurs are more eager to invest. Thereby, our investment model helps to explain differences in investment behavior in situations which are objectively identical

Deformation independent open brane metrics and generalized theta parameters

We investigate the consequences of generalizing certain well established properties of the open string metric to the conjectured open membrane and open Dp-brane metrics. By imposing deformation independence on these metrics their functional dependence on the background fields can be determined including the notorious conformal factor. In analogy with the non-commutativity parameter $\Theta^{\mu\nu}$ in the string case, we also obtain `generalized' theta parameters which are rank q+1 antisymmetric tensors (polyvectors) for open Dq-branes and rank 3 for the open membrane case. The expressions we obtain for the open membrane quantities are expected to be valid for general background field configurations, while the open D-brane quantities are only valid for one parameter deformations. By reducing the open membrane data to five dimensions, we show that they, modulo a subtlety with implications for the relation between OM-theory and NCYM, correctly generate the open string and open D2-data.Comment: 24 pages, LaTe

Nurturing lifelong learning in communities through the National University of Lesotho: prospects and challenges

This paper analyses one aspect of a pan-African action research project called ITMUA (Implementing the Third Mission of Universities in Africa). This particular paper draws on the data from that project to explore the National University of Lesotho’s contribution to lifelong learning in its communities. It provides background information on the ITMUA initiative and analyses interview and focus group responses to two case studies in terms of their contribution to lifelong learning. It uses, as its analytical framework, a modified version of Mbigi’s African perspective on the four De Lors’ ‘pillars’, by adding a fifth pillar, courtesy of Torres. The paper argues that community engagement is a two-way process between universities and their wider constituencies with opportunities for mutual lifelong learning. But there are also challenges of understanding and process which must be addressed if the full range of these lifelong learning pillars is to be accommodated within African contexts. The paper provides an introduction to the history of community engagement in Africa as a university mission, followed by a brief discussion of lifelong learning within African perspectives. After describing the particular context of Lesotho, the concept of community service and community engagement in contemporary African contexts introduces the action research project and the case studies. The final part of the paper presents and discusses the research findings

Experimental and Computational Studies of Single-Molecule Conductance of Ru(II) and Pt(II) trans-Bis(acetylide) Complexes

The single-molecule conductance of metal complexes of the general forms trans-Ru(C≡CArC≡CY)2(dppe)2 and trans-Pt(C≡CArC≡CY)2(PPh3)2 (Ar = 1,4-C6H2-2,5-(OC6H13)2; Y = 4-C5H4N, 4-C6H4SMe) have been determined using the STM I(s) technique. The complexes display high conductance (Y = 4-C5H4N, M = Ru (0.4 ± 0.18 nS), Pt (0.8 ± 0.5 nS); Y = 4-C6H5SMe, M = Ru (1.4 ± 0.4 nS), Pt (1.8 ± 0.6 nS)) for molecular structures of ca. 3 nm in length, which has been attributed to transport processes arising from tunneling through the tails of LUMO state

Continuous variable entanglement and quantum state teleportation between optical and macroscopic vibrational modes through radiation pressure

We study an isolated, perfectly reflecting, mirror illuminated by an intense laser pulse. We show that the resulting radiation pressure efficiently entangles a mirror vibrational mode with the two reflected optical sideband modes of the incident carrier beam. The entanglement of the resulting three-mode state is studied in detail and it is shown to be robust against the mirror mode temperature. We then show how this continuous variable entanglement can be profitably used to teleport an unknown quantum state of an optical mode onto the vibrational mode of the mirror.Comment: 18 pages, 10 figure