Pre-resonance effects in deep UV Raman spectra of normal and deuterated water.

We have investigated the shape of the OH/OD stretching Raman band of water as a function of the excitation wavelength in the deep UV region (200-266 nm). By analyzing the spectral profiles, we highlighted selective pre-resonance effects in the high wavenumber component of the OH/OD stretching band, associated to distorted H-bonded water configurations. A van't Hoff treatment of the temperature-dependent Raman spectra provides an estimate of the thermal energy associated to the change from ordered (ice-like) to disordered configurations that agrees with values obtained by related methods based on a two-state model of water. These results open the possibility of exploiting the observed pre-resonance deep-UV signal enhancement to investigate H-bonding properties in aqueous media.

The controlled pulsed laser deposition of Ag nanoparticle arrays for surface enhanced Raman scattering.

An effective method for the production of surface enhanced Raman scattering (SERS) active substrates is presented. Nanostructured silver thin films are pulsed laser deposited in an argon atmosphere. The films consist of arrays of nanoparticles whose size is controlled by the Ar pressure. The surface morphology of the films can be tuned by the laser pulse number. Nanoparticle size is calculated by a phenomenological model taking into account the dynamics of the laser generated silver plasma. The SERS activity of the films is investigated by Raman scattering of adsorbed rhodamine 6G at different concentrations.

Elemental distribution in fluorinated amorphous carbon thin films.

Focused ion beam-secondary ion mass spectrometry (FIB-SIMS) with 20 nm spatial resolution has been used to analyze amorphous fluorinated carbon thin films, deposited by plasma assisted chemical vapor deposition (PACVD), at micro- to nano-scale. Mass spectra and ion imaging of film surface were acquired and the presence and distribution of contaminants were investigated. Surface images show the secondary ion distribution for F(-), CH(-), CF(-). A change in size and topology of fluorine-rich areas is correlated with film hardness and with microstructure transition from diamond-like to polymer-like, as indicated by infrared and Raman spectroscopies. Based on the surface distributions of CF(-) and CH(-) and on the vibrational spectroscopy results, a mechanism of fluorine substitution for hydrogen and an attempt to explain the film structure and microstructure is proposed.

Respiratory snorkel and valve system for breath-by-breath gas analysis in swimming.

The present study aimed to compare a standard facemask (CM) and a newly modified swimming snorkel and valve system (SV) for breath-by-breath (BxB) gas analysis (K4 b2, Cosmed, Rome, Italy), and to validate the system under controlled laboratory conditions before being used in swimming. Nine healthy males performed two bouts of a stepwise exercise on an electrically braked stationary bicycle on separate days. Ventilatory and gas exchange parameters were analyzed using the same BxB portable system, with subjects breathing alternatively through the two different valves. Agreement between both methods was evaluated by Passing-Bablok regression analysis. The gas exchange values measured using the SV were highly correlated with those obtained using the CM (R2 values >0.9). However, differences existed between the two series of measurements so that most ventilatory and gas exchange parameters were lower (3-7%) with the SV. The error when using the SV device was mainly systematic along the whole range of measurement. Accordingly, linear regression equations were developed to further improve the accuracy of the measures when using the SV. Therefore, the modified respiratory SV system can be considered as a valid device for collecting expired gas for BxB analysis, comparable to the standard facemask, with the advantage of being suitable for measurements during swimming.

Management of hilar bile duct carcinoma.

BACKGROUND/AIMS: Hilar cholangiocarcinoma is a rare tumor with a dismal prognosis. Because proximal bile duct cancers are uncommon, outcomes related to various therapeutic interventions are not well defined. METHODOLOGY: Between 1985 and 1997, 55 patients with bile duct cancers involving the proximal third of the extrahepatic bile ducts were seen. The management of patients with resectable and unresectable disease was retrospectively reviewed. All but four patients were followed until the time of death. RESULTS: Forty patients underwent laparotomy following preoperative assessment of extent of disease and 19 patients (35%) ultimately underwent resection with curative intent. Survival was significantly longer in patients who underwent resection (2-year survival 47% vs. 18%; P = 0.027). Of those patients whose disease was resected, 11 patients received adjuvant radiotherapy. Survival for this group was not significantly different from that seen in patients who did not receive adjuvant radiotherapy. Similarly, in patients with unresectable disease, administration of radiotherapy was not associated with an improved outcome. CONCLUSIONS: Locoregional extent of disease is the greatest problem in cases of proximal bile duct cancers. Resection provides the best hope for long-term survival, but new adjuvant strategies are needed.

A subcutaneous or subfascial jejunostomy is beneficial in the surgical management of extrahepatic bile duct cancers.

BACKGROUND: Extrahepatic bile duct cancers are rare tumors with a dismal prognosis. Even after a resection, obstructive cholestasis and other biliary complications are the rule. To facilitate retrograde access to the biliary tree for treatment of such biliary complications, a modified Roux-en-Y hepaticojejunostomy is constructed such that the afferent limb is brought up as a subcutaneous or subfascial jejunostomy (SJ). The safety and utility of construction of an SJ was evaluated in patients with extrahepatic cholangiocarcinoma. METHODS: From 1985 to 1997, 24 patients with extrahepatic bile duct cancers received an SJ as part of their management. Demographic data, operative data, tumor characteristics, and postoperative courses were retrospectively reviewed. All but 3 patients were followed to the time of death. RESULTS: The average age of the patients was 62 +/- 9 years. The tumor was resected in 17 patients. Major complications occurred in 5 patients (21%). There was 1 operative death (4%). None of the complications could be attributed to construction of the SJ, although 1 patient had a soft tissue infection at the site of the percutaneous access of the SJ. Frequent dilatations of biliary strictures were required in 5 patients, and 1 patient eventually required insertion of an internal biliary stent. These procedures could all be accomplished through the SJ. CONCLUSIONS: The SJ is a technically simple and safe addition to the management of resectable and unresectable extrahepatic bile duct cancers, particularly proximal lesions. The procedure facilitates brachytherapy if indicated, and it allows convenient management of postoperative biliary complications, including recurrent strictures.

Is central nervous system prophylaxis necessary in ocular adnexal lymphoma?

PURPOSE: To examine the frequency of metastasis to the eye and central nervous system (CNS) from ocular adnexal lymphomas and to evaluate whether CNS prophylaxis is appropriate for these tumors. PATIENTS AND METHODS: Seventy-one patients with biopsy-confirmed ocular adnexal lymphomas were evaluated between 1989 and 1995. The lymphomas were subclassified histopathologically according to the new Revised European-American Lymphoma (REAL) criteria. Molecular genetic analysis of tumor cell DNA was done by Southern blot. Patients had a complete ophthalmologic evaluation and metastatic work-up and were then routinely followed up by an ophthalmologist and a medical oncologist. RESULTS: The 34 men and 37 women studied had a median age of 67 years (23 to 92). Ocular adnexal lymphomas were situated in the orbit in 54 patients, in the conjunctiva in 14 patients, and in the eyelid in 3 patients. Bilateral involvement occurred in 11 patients. The most common histologic diagnoses were (54 patients, 76%) extra-nodal marginal zone lymphomas and small lymphocytic lymphomas in 10 patients (14%). Molecular genetic analysis performed in all patients confirmed a monoclonal B-cell population in 55 patients (77%), including a single rearrangement of the immunoglobulin heavy chain gene in 14 patients, and more than two rearrangements in 41 patients. No patients had isolated T-cell gene rearrangements. Localized ocular adnexal lymphoma was diagnosed in 43 patients (61%), 17 patients (24%) were found to have concurrent extraocular lymphoma on metastatic work-up and 11 patients (15%) had a previous diagnosis of systemic lymphoma before the onset of their ocular tumor. The median duration of follow-up was 20 months. Overall, 32 patients (45%) had tumors, which remained localized to the orbit adnexa. Eleven patients (15%) relapsed, but none had eye or central nervous system involvement nor required CNS-directed therapy. Although eight patients died, only two died as a direct result of systemic lymphoma. No patient received CNS prophylaxis with either intrathecal chemotherapy and/or radiation therapy. CONCLUSION: Ocular adnexal lymphomas are rare non-Hodgkin's B-cell lymphomas. Metastatic involvement of the eye or central nervous system is rare and CNS prophylaxis with radiotherapy or chemotherapy is unnecessary.