Force Curve Measurements with the AFM: Application to the In Situ Determination of Grafted Silicon-Wafer Surface Energies

The atomic force microscope (AFM) can be used to perform surface force measurements in the quasi-static mode (cantilever is not oscillating) to investigate nanoscale surface properties. Nevertheless, there is still a lack of literature proposing a complete systematic and rigorous experimental procedure that enables one to obtain reproducible and significant quantitative data. This article focuses on the fundamental experimental difficulties arising when making force curve measurements with the AFM in air. On the basis of this AFM calibration procedure, quantitative assessment values were used to determine, in situ, SAM (or Self Assembled Monolayer)-tip thermodynamic work of adhesion at a local scale, which have been found to be in good agreement with quoted values. Finally, determination of surface energies of functionalised silicon wafers (as received, CH₃, OH functionalised silicon wafers) with the AFM (at a local scale) is also proposed and compared with the values obtained by wettability (at a macroscopic scale). In particular, the effect of the capillary forces is discussed.     

Corticosteroids significantly delay the onset of docetaxel-induced fluid retention: final results of a randomized study of the European Organization for Research and Treatment of Cancer Investigational Drug Branch for Breast Cancer

PURPOSE: To confirm the efficacy of docetaxel in patients with breast cancer previously treated with one chemotherapy regimen for advanced or metastatic disease and to compare the incidence of fluid retention (FR) and skin toxicity when docetaxel is administered with and without prophylactic corticosteroids. PATIENTS AND METHODS: Eighty-three patients, pretreated with one chemotherapy regimen for metastatic breast cancer (MBC) with bidimensionally measurable and progressive disease, were eligible for this randomized trial. Docetaxel with prophylactic oral antihistamine was administered at a dose of 50 mg/m2 as a 1-hour infusion on days 1 and 8 every 21 days and patients were randomized to receive methylprednisolone (40 mg days -1, 0, 1, 7, 8, and 9 of each cycle) (arm A) or no methylprednisolone (arm B). RESULTS: Twenty-eight patients (34%, 95% confidence interval [CI], 23% to 45%) achieved on objective response. The median time to disease progression and median overall survival time were 5 and 13.5 months, respectively. In total, 415 cycles of docetaxel were administered (arm A: N = 219, median = six; arm B: N = 196, median = five). The most common toxicity observed was grade 3 or 4 neutropenia, which occurred in 79% of patients. Clinically significant nonhematologic side effects included skin reactions and asthenia. In an intent-to-treat analysis, patients who received methylprednisolone premedication had a delayed onset of FR (median time to onset of FR: arm A, 84 days; arm B, 62 days; P = .01) and received a higher median cumulative dose of docetaxel before the onset of FR (arm A, 333 mg/m2; arm B, 215 mg/m2; P = .001). There was no statistically significant difference in the incidence of skin toxicity between the two arms. CONCLUSION: Docetaxel, at this dose and schedule, has definite antitumor activity in pretreated MBC patients. Moreover, this is the first randomized trial to show that corticosteroids have a favorable impact on docetaxel-induced FR.     

The use of forest-derived specific gravity for the conversion of volume to biomass for open-grown trees on agricultural land

Accounting for agroforestry contributions to carbon sequestration and cellulosic feedstock production requires biomass equations that accurately estimate biomass in open-grown trees. Since equations for open-grown trees are rare and developing these is expensive, existing forest-based equations are an attractive alternative for open-grown trees in carbon accounting and biomass modeling. How accurate this alternative is depends on how similar the key attributes, such as specific gravity, trunk shape, and crown architecture, are between open- and forest-grown trees. We evaluated the use of forest-derived specific gravity for conversion of volume to biomass for morphologically distinct open-grown species: green ash, ponderosa pine, and eastern redcedar. Trunk biomass was consistently and significantly underestimated from 6.3% to 16.6% depending on species, indicating open-grown trees have greater trunk specific gravity than forest-grown counterparts within the same geographic region; however a conclusive difference in branch specific gravity was not found between open- and forest-grown trees. Open-grown trees have greater trunk specific gravity, sharper trunk taper, and larger crown. When forest-based equations are used for trunk biomass of open-grown trees, the greater trunk specific gravity results in underestimation; however, the sharper trunk taper results in overestimation. Studies are needed to examine whether the underestimation could be offset by the overestimation and how the larger crown affects biomass estimation when forest-based equations are used for open-grown trees. Our results provide an essential understanding to interpret the biometric relationship of open- to forest-grown trees and to develop an efficient means how forest-based equations might be best modified for open-grown trees.     

Determining factors that impact the calibration of consumer-grade digital cameras used for vegetation analysis

Digital cameras can collect quantitative leaf data, such as chlorophyll content and leaf area index (LAI), because they act as a simple broadband radiometer. However, a cross-calibration between cameras is needed for the purpose of extracting vegetation information from various image repositories. The objective of this study was to examine the variation between multiple consumer-grade camera types – single reflex lens (SLR), point-and-shoot, and cellphone cameras – for the purpose of collecting reliable quantitative data when monitoring vegetation. The specific objectives were to: 1) identify the optimal light conditions for the calibration procedure, 2) determine the variability of exposure value (EV)-corrected calibrated digital numbers (cDN_ev) values among eight consumer-grade digital cameras, and 3) compare the cDN_ev values with the raw digital numbers (DN), exposure-adjusted digital numbers (DN_ev), and calibrated digital numbers (cDN) as these latter three components are easier to compute. This study demonstrated that light intensity was important for calibrating cameras to ensure sensor saturation, and that an improper white-balance setting can negatively impact data collection. In one experiment, the coefficient of variation (CV) between the eight cameras examined in the study was reduced from 29% using raw DN to 16% using cDN_ev values. Likewise, the root mean square error in estimating leaf chlorophyll-a using a common vegetation index for digital camera, excess green index (EGI), was reduced from 131 to 96 mg g^?2. However, for both experiments, there was only a weak statistical difference between cDN_ev and DN_ev, indicating that exposure information was the most useful in minimizing the differences between cameras. Although digital cameras are not nearly as accurate as specialized remote-sensing equipment, they do offer the potential for greater collection opportunities. This study demonstrates the potential of using consumer-grade digital cameras to derive quantitative information from citizen science projects.     

Energy and Hydraulic Performance-Based Management of Large-Scale Pressurized Irrigation Systems

Improving energy and hydraulic performance of large-scale pressurized irrigation is now perceived as a very pressing need, after large budgets have been allocated into systems modernization. This paper tackles this priority area by developing a management oriented multi-step methodology, that integrates different existing models, to sector the system according to the pressure requirements of the hydrants, and to regulate the pumping station for i) a fixed and a variable pressure head control, and for ii) an enhanced performance. When applied to an on-demand system in the Sinistra Ofanto irrigation scheme of Foggia (Italy), this integrated approach showed potential for energy saving under the optimal scenario of 49 %, and noticeable improvement in the system performance in terms of hydrant pressure heads, as compared to the actual conditions. The monetary assessment demonstrates that the achieved energy saving amounts to 23,636 Euros per irrigation season, 45 % among which are due to sectoring.     

Effect of conductivity uncertainties and modeling errors on EEGsource localization using a 2-D model

This paper presents a sensitivity study electroencephalography-based source localization due errors in the head-tissue conductivities and to errors in modeling the conductivity variation inside the brain and scalp. The study is conducted using a two-dimensional (2-D) finite element model obtained from a magnetic resonance imaging (MRI) scan of a head cross section. The effect of uncertainty in the following tissues is studied: white matter, gray matter, cerebrospinal fluid (CSF), skull, and fat. The distribution of source location errors, assuming a single-dipole source model, is examined in detail for different dipole locations over the entire brain region. We also present a detailed analysis of the effect of conductivity on source localization for a four-layer cylinder model and a four-layer sphere model. These two simple models provide insight into how the effect of conductivity on boundary potential translates into source location errors; and also how errors in a 2-D model compare to errors in a three-dimensional model. Results presented in this paper clearly point to the following conclusion: unless the conductivities of the head tissues and the distribution of these tissues throughout the head are modeled accurately, the goal of achieving localization accuracy to within a few millimeters is unattainable     

Gemcitabine: a new chemotherapy agent for solid cancers

Gemcitabine, a new nucleotide analogue, is a promising chemotherapeutic agent for pancreatic, lung, ovarian and breast carcinomas. Its low toxicity (mainly hematologic) makes it a good choice for palliative treatment in patients who would otherwise be unable to tolerate aggressive therapy. The combination of gemcitabine with other anticancer agents such as cisplatin and anthracyclines appears to be associated with high response rates. Finally, gemcitabine is a potent radiosensitizing agent and should definitely be tested in combination with radiotherapy mainly in locally advanced disease.     

Conjugated-polymer grafting on inorganic and organic substrates: A new trend in organic electronic materials

This review highlights recent developments in the grafting of conjugated polymers onto various substrates for organic electronic devices. The rapid development of multi-layer architectures demands the preparation of well-defined interfaces between both compatible and incompatible materials. It is promising therefore that interface-engineering is now known to help passivate charge trap states, control energy level alignments, enhance charge extraction, guide active-layer morphologies, and improve material compatibility, adhesion and device stability. In organic electronic devices, conjugated polymers are in contact with a wide range of constituents, such as metals, metal oxides, organic materials, and inorganic particles. Covalent bonds between these materials and macromolecules are desired to yield intimate contacts and well-defined interfaces. Following an overview of the various synthetic methodologies of conjugated polymers, the chemistry of tethering macromolecular chains onto nanoparticles and flat surfaces is described. The creation of functional hybrid materials offers the potential to deliver efficient and low-cost devices.