Hesham Taha

We present a unique atomic force microscope [AFM] probe for tip enhanced Raman scattering [TERS] and a new form of near-field microscopy, ``Shadow Near-field Scanning Optical Microscopy''. The probe consists of a single gold nanoparticle grown at the tip of a cantilevered nanopipette, exposed to the optical axis of an upright or inverted optical microscope. When these probes are used in combination with a Nanonics MV 2000 AFM/NSOM system, we show that a protocol for independent motion of the probe and the sample can produce enhancement or a shadow effect. Both of these effects are enhanced by the ability to affect different Raman spectra with the tip in & out of contact while independently scanning the sample. We analyzed Raman signals of a thin nanometric strained Si layer deposited on bulk Si and developed an understanding of optical mechanisms of enhancement, scattering and shadowing. Our results show different optical mechanisms occur as a result of tip & sample interactions, including TERS effect obtained by near-field interaction of the probe with the top layer of strained Si. Large enhancements of at least 4 orders of magnitude are seen and analyses of relative intensities of bulk and strained Si Raman peaks show an increase in light scattered by bulk or effective shadowing of the surface.

A scanning electron microscope compatible platform that permits multiprobe atomic force microscopy based nanoelectrical characterization will be described. To achieve such multiple parameter nanocharacterization with scanning electron microscope compatibility ...

Although metals are commonly shiny and highly reflective, we here show that thin metal films appear black when deposited on a dielectric with antireflective moth-eye nanostructures. The nanostructures were tapered and close-packed, with heights in the range 300-600 nm, and a lateral, spatial frequency in the range 5-7 μm(-1). A reflectance in the visible spectrum as low as 6%, and an absorbance of 90% was observed for an Al film of 100 nm thickness. Corresponding experiments on a planar film yielded 80% reflectance and 20% absorbance. The observed absorbance enhancement is attributed to a gradient effect causing the metal film to be antireflective, analogous to the mechanism in dielectrics and semiconductors. We find that the investigated nanostructures have too large spatial frequency to facilitate efficient coupling to the otherwise non-radiating surface plasmons. Applications for decoration and displays are discussed.

One of the pressing problems in advancing nanoelectronic applications and systems is to develop a simple means of freely connecting at a nanometric level electronic components under ambient conditions without the need for vacuum or electron or ion beam operational steps. Such environments may have detrimental effects on the molecular or biomolecular constituents of molecular electronic circuits. Although there has been defined progress in connecting structures that are of nanometric dimension, new methods in this area of nanotechnology with general applicability add to the arsenal of tools for addressing this standing problem. This paper addresses freely placing under ambient conditions, with fountain pen nanolithography, a 120 nm dimension line of gold nanocolloids deposited with precise registration in a 100 nm gap between two 250 nm wide conducting electrodes patterned by electron beam lithography.

Bilateral vocal cord paralysis is uncommon. Most cases occur secondary to trauma, malignancy, surgery, or intubation. Also, it was reported as a side effect of Vinca alkaloids. We report a patient with small cell lung cancer who developed bilateral vocal cord paralysis and needed to be intubated after treatment with cisplatin and etoposide. All workups excluded metastases as a cause of bilateral vocal cord paralysis. The patient required tracheostomy; she did not receive any further chemotherapy. After 11 weeks, vocal cord paralysis disappeared, tracheostomy was reversed, and the patient remained symptom free; however, 6 months later, the patient developed brain and liver metastases and died from her disease with no evidence of vocal cord paralysis. We report a case of reversible bilateral vocal cord paralysis that we believe to be secondary to cisplatin toxicity, which is an undescribed complication of this drug. Cisplatin can induce reversible bilateral vocal cord paralysis. The concurrent use of cisplatin and etoposide might have contributed to this complication in our patient.

The management of locally advanced head and neck cancer remains a challenge to most oncologists and their patients. Treatment with epithelial growth factor receptor inhibitors (EGFRIs) is associated with a good response. Cetuximab, a chimeric monoclonal antibody directed against epithelial growth factor receptor (EGFR), in combination with radiation therapy is indicated for the treatment of locally advanced squamous cell carcinoma of the head and neck. Although a mild acneiform skin rash (Grade 1, 2) is very common in these patients, severe rash (Grade 3) is uncommon. A 61-year-old African American man with locally advanced oropharyngeal cancer was treated with cetuximab and radiation. He developed a sudden flare-up of a skin rash after the 5th cycle of cetuximab following use of over-the-counter (OTC) skin care remedies. The rash manifested with severe maculopapular eruption and erythematous rash, along with desquamation and exfoliation of the skin, mainly on the face and neck area. The patient denied any extraordinary sun exposure. Cetuximab and radiation therapy were held for 1 week and the rash was treated with doxycycline, diphenhydramine, and continued use of natural emollient (Vaseline petroleum jelly). After 1 week, a dramatic improvement of the facial rash was noticed. Our report describes a sudden flare-up of a skin rash (Grade 3) after the 5th cycle of cetuximab following use of OTC skin care remedies, which was unusual for this patient, suggesting a possible relation to the therapy. Skin crucially depends on EGFR for its normal function and becomes extremely sensitive during cetuximab therapy. Topical OTC acne and dry skin remedies can suddenly change the mild acneiform rash into severe skin toxicity associated with marked desquamation and exfoliation. Avoidance of further skin damage caused by topical applications and the use of doxycycline and diphenhydramine show a significant success in the management of skin toxicity.