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Sequential addition of a polyanion, poly(styrene sulfonate), and a polycation, polyaniline, lead to the formation of layer-by-layer films at different solid surfaces. The prime variables which determine the films formation of poly(styrene sulfonate) (PSS)/polyaniline (PANI) were the polymer charge and ionic strength. The films were deposited by selecting organic/inorganic acid media at pH 2.8. The building up of such multilayer films was characterized by the increment of the adsorbed amount through UV−visible spectroscopy. A linear increase in the absorption magnitude was measured from 1 to 25 bilayers. The uniformity of the PSS/PANI layer-by-layer (LBL) films could be well-maintained, undoping the films in NaOH for obtaining an emeraldine base form of polyaniline. The built-up multilayers were investigated by atomic force microscopy, scanning tunneling microscopy, and cyclic voltammetric and electrical conductivity measurements. The interesting feature of the nearly equal grain size was noticed between 4 and 15 bilayer films of PSS/PANI. The surface roughness was distinguished beyond 15 bilayers of LBL films. The cyclic voltammogram showed the change in the peaks potential value going from 1 to 20 bilayers. The inhomogeneity incorporated inside the films slowed down the electrochemical kinetics in the PSS/PANI bilayers while going from 1 to 25 bilayer films. The diffusion coefficient (D 0) of PSS/PANI 10 bilayers was estimated to be 2 × 10-8 cm2 s-1. Such multilayer films exhibit conductivity in the area of 0.1 S/cm.

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Background:Ideally, the intensity of postoperative pain should be predicted so as to customize analgesia. The objective of this study was to investigate whether preoperative electrical and pressure pain assessment can predict post-caesarean section pain and analgesic requirement.Materials and Methods:A total of 65 subjects scheduled for elective caesarean section, who gave written informed consent, were studied. Preoperatively, PainMatcher® was used to evaluate electrical pain threshold, while manual PainTest™ FPN 100 Algometer and digital PainTest™ FPX 25 Algometer determined pressure pain threshold and tolerance. Postoperatively, numerical rating scales were used to assess pain at regular time intervals. Patients received intramuscular pethidine (100mg, 6 hourly), rectal diclofenac (100mg, 12 hourly), and oral paracetamol (1g, p.r.n.) for pain relief. Statistical analysis was conducted using PASW Statistics 18 software.Results:Preoperative electrical pain threshold correlated significantly with post-caesarean pain scores at 6 and 24 hours (r = –0.26, P < 0.02; r = –0.23, P < 0.04, respectively), and with the quantity of paracetamol consumed by the patient within 48 hours of surgery (r = –0.33, P < 0.005). Preoperative pressure pain tolerance measured by PainTest™ FPX 25 Algometer was significantly correlated with pain scores 6 hours postsurgery (r = –0.21, P < 0.05). Pain scores 6 hours post-caesarean section correlated significantly with anesthesia—general or spinal (F = 4.22, v1 = 1, v2 = 63, P < 0.05).Conclusions:The predictive methods proposed may aid in identifying patients at greater risk for postoperative pain. Electrical pain threshold could be useful in personalizing the postoperative analgesic protocol.

Nanoscale science and technology is today mainly focused on the fabrication of nanodevices. Our approach makes use of lithography processes to build the desired nanostructures directly. The fabrication process involves an electron-beam lithography technique to define metallic microstructures onto which nanometre scale patterning is performed using an atomic force microscope (AFM) as a mechanical modification tool. Both direct material removal and AFM-assisted mask patterning are applied in order to achieve the smallest possible separation between electrode pairs. The sample preparation involves a polymer deposition process that results in conformal growth and in surface roughness comparable to that of the substrate. The results of the application of this technique show that the process is reproducible and exhibits a good operation control during the lithographic steps, both ensured by the imaging facilities of the AFM. The nanolithography technique has been used to fabricate nanogap electrodes to be used for molecular devices. The study reported here can be considered as a reliable starting point for the development of more complex nanodevices, such as single-electron transistors.