Electrical determination of the valence-band discontinuity in HgTe-CdTe heterojunctions

Current-voltage behavior is studied experimentally in a Hg0.78Cd0.22Te-CdTe-Hg0.78Cd0.22Te heterostructure grown by molecular beam epitaxy. At temperatures above 160 K, energy-band diagrams suggest that the dominant low-bias current is thermionic hole emission across the CdTe barrier layer. This interpretation yields a direct determination of 390±75 meV for the HgTe-CdTe valence-band discontinuity at 300 K. Similar analyses of current-voltage data taken at 190–300 K suggest that the valence-band offset decreases at low temperatures in this heterojunction

Current transport mechanisms in GaAs/AlAs tunnel structures grown by metal–organic chemical vapor deposition

Elastic and inelastic tunneling processes are investigated in GaAs–AlAs–GaAs double heterojunctions grown in the [100] direction by metal–organic chemical vapor deposition (MOCVD). The AlAs quantum barriers in the heterostructures studied are doped p-type with Mg. Theoretical calculations of tunneling currents are performed and compared with experimental I–V data. It is found that for structures with thin AlAs barriers, the dominant current transport mechanism at low temperatures is tunneling through the AlAs band gap at both the Gamma and X points. This is consistent with inelastic processes observable in first (dI/dV) and second (d2I/dV2) derivative spectra obtained with modulation techniques. A simple model, developed for calculating impurity-assisted tunneling currents, shows that the role of barrier impurities becomes more important as the barrier is grown thicker. Implications of some of these results for resonant tunneling heterostructures consisting of two AlAs quantum barriers separated by a GaAs quantum well are discussed. Experimental second derivative spectra showing reproducible features are also presented for these double barrier structures

Infusional ECarboF in patients with advanced breast cancer: A very active and well-tolerated out-patient regimen

We performed a trial using the combination of epirubicin 50 mg/m2/day 1, carboplatinum AUC 5/day 1 and continuous 5-fluorouracil (5-FU) 200 mg/m2/day (every 4 weeks for 6 months) to confirm the efficacy and low toxicity profile of this regimen in breast cancer. In 51 patients with metastatic (n = 33) or locally advanced (n=18) breast cancer the overall response rate was 86% (95% confidence interval (95% CI): 73%-94%): 94% in locally advanced and 81% metastatic disease. Grade 3-4 toxicity was low: 4% of patients presented with febrile neutropenia, 16% with severe palmar-plantar syndrome, 10% with Port-a-cath thrombosis. This study confirms the high efficacy of infusional 5-FU-based regimens and justifies further research into novel promising oral 5-FU derivative

Approaches towards expression profiling the response to treatment

Over the past 8 years there has been a wealth of breast cancer gene expression studies. The majority of these studies have focused upon characterising a tumour at presentation, before treatment, rather than looking at the effects of treatment on the tumour. More recently, a number of groups have moved from predicting prognosis based upon long-term follow-up to alternative approaches of using expression profiling to measure the effect of treatment on breast tumours and potentially predict response to therapy using either post-treatment samples or both pre-treatment and post-treatment samples. Whilst this provides great potential to further our understanding of the mode of action of treatments and to more accurately select which patients will benefit from a particular treatment, serious issues of experimental design must be considered