Nanocrystalline cellulose applied simultaneously as the gate dielectric and the substrate in flexible field effect transistors

Cotton-based nanocrystalline cellulose (NCC), also known as nanopaper, one of the major sources of renewable materials, is a promising substrate and component for producing low cost fully recyclable flexible paper electronic devices and systems due to its properties (lightweight, stiffness, non-toxicity, transparency, low thermal expansion, gas impermeability and improved mechanical properties).Here, we have demonstrated for the first time a thin transparent nanopaper-based field effect transistor (FET) where NCC is simultaneously used as the substrate and as the gate dielectric layer in an 'interstrate' structure, since the device is built on both sides of the NCC films; while the active channel layer is based on oxide amorphous semiconductors, the gate electrode is based on a transparent conductive oxide.Such hybrid FETs present excellent operating characteristics such as high channel saturation mobility (>7 cm(2) V (-1) s(-1)), drain-source current on/off modulation ratio higher than 10(5), enhancement n-type operation and subthreshold gate voltage swing of 2.11 V/decade. The NCC film FET characteristics have been measured in air ambient conditions and present good stability, after two weeks of being processed, without any type of encapsulation or passivation layer. The results obtained are comparable to ones produced for conventional cellulose paper, marking this out as a promising approach for attaining high-performance disposable electronics such as paper displays, smart labels, smart packaging, RFID (radio-frequency identification) and point-of-care systems for self-analysis in bioscience applications, among others.

Recombinant hirudin in patients with chronic, stable coronary artery disease. Safety, half-life, and effect on coagulation parameters

BACKGROUND

Because the specific antithrombin hirudin prevents platelet-rich arterial thrombus and accelerates thrombolysis in a variety of animal models, it has promise as antithrombotic therapy. We therefore studied the half-life, effect on anticoagulant parameters, and safety of hirudin in patients with coronary artery disease.

METHODS AND RESULTS

Thirty-eight men and 1 woman (age [mean +/- SD], 60.4 +/- 6.9 years) with angiographic coronary disease were allocated in a single-blind ascending dosage study to a 6-hour i.v. infusion of recombinant hirudin (CGP 39,393) or matching placebo. The median terminal half-life for hirudin, measured by ELISA, was 2.7, 2.3, 2.9, 3.1, and 2.0 hours for the 0.02, 0.05, 0.1, 0.2, and 0.3 mg.kg-1 x h-1 groups, respectively. Activated partial thromboplastin times (aPTT) at 3, 4, and 6 hours were averaged into a plateau value. The aPTT plateau-to-baseline ratios were 1.5 +/- 0.1, 2.0 +/- 0.1, 2.3 +/- 0.1, 2.7 +/- 0.1, and 2.9 +/- 0.1, respectively, with hirudin infused at 0.02, 0.05, 0.1, 0.2, and 0.3 mg.kg-1 x h-1. From 62% to 77% of the aPTT plateau value was seen within 30 minutes of starting the infusions and was directly related to dose. The aPTT-to-baseline ratios correlated well with plasma hirudin levels (r = .88), whereas poor correlation and sensitivity were observed between plasma hirudin levels and activated coagulation time (ACT)-to-baseline ratios (r = .44). Plasma levels of hirudin and ACT in seconds correlated overall well (r = .80), but considerable overlap occurred between baseline ACT and ACT at plasma hirudin concentrations < 1000 ng/mL. Prothrombin times were significantly prolonged only at a dosage of > or = 0.05 mg.kg-1 x h-1 and were 11.8 +/- 0.5 (INR = 1.0), 12.3 +/- 0.7 (INR = 1.1), 13.3 +/- 1.2 (INR = 1.4), 14.2 +/- 0.4 (INR = 1.7), and 15.8 +/- 0.9 (INR = 2.3) seconds for each respective hirudin dosage. Thrombin times were beyond range (> 600 seconds) at 6 hours in all except 2 patients who received the lowest dosage. All parameters returned to baseline between 8 and 18 hours after the infusion. Bleeding times were not significantly prolonged. No side effects occurred. No antibodies to hirudin were detected 2 weeks after the infusion.

CONCLUSIONS

Recombinant hirudin has a terminal half-life of 2 to 3 hours. The aPTT correlates well with plasma levels of hirudin and allows close titration over a wide range of anticoagulation, while ACT and prothrombin time are relatively insensitive for monitoring hirudin administration. At anticoagulant levels effective in experimental thrombosis, a 6-hour infusion of hirudin is well tolerated and safe in a predominantly male group of patients with stable coronary atherosclerosis.

Influence of the layer thickness in plasmonic gold nanoparticles produced by thermal evaporation

Metallic nanoparticles (NPs) have received recently considerable interest of photonic and photovoltaic communities. In this work, we report the optoelectronic properties of gold NPs (Au-NPs) obtained by depositing very thin gold layers on glass substrates through thermal evaporation electron-beam assisted process. The effect of mass thickness of the layer was evaluated. The polycrystalline Au-NPs, with grain sizes of 14 and 19 nm tend to be elongated in one direction as the mass thickness increase. A 2 nm layer deposited at 250°C led to the formation of Au-NPs with 10-20 nm average size, obtained by SEM images, while for a 5 nm layer the wide size elongates from 25 to 150 nm with a mean at 75 nm. In the near infrared region was observed an absorption enhancement of amorphous silicon films deposited onto the Au-NPs layers with a corresponding increase in the PL peak for the same wavelength region.

The influence of fibril composition and dimension on the performance of paper gated oxide transistors

Paper electronics is a topic of great interest due the possibility of having low-cost, disposable and recyclable electronic devices. The final goal is to make paper itself an active part of such devices. In this work we present new approaches in the selection of tailored paper, aiming to use it simultaneously as substrate and dielectric in oxide based paper field effect transistors (FETs). From the work performed, it was observed that the gate leakage current in paper FETs can be reduced using a dense microfiber/nanofiber cellulose paper as the dielectric. Also, the stability of these devices against changes in relative humidity is improved. On other hand, if the pH of the microfiber/nanofiber cellulose pulp is modified by the addition of HCl, the saturation mobility of the devices increases up to 16 cm(2) V(-1) s(-1), with an ION/IOFF ratio close to 10(5).

[Neurophysins, vasopressin and cognitive function in aging]

Neurophysins, vasopressin and oxytocin are not restricted to the hypothalamo-neuropituitary system but are also found in different brain area in relation with cognitive and emotional function and with cardiovascular regulation. During early aging it seems to exist a decrease of the hypothalamic and brain content of vasopressin. It appears that in some patients, presumably suffering from a deficit of central vasopressinergic function, exogenous vasopressin could improve arousal and/or memory. The exact place of this peptide in the treatment of the early aging cognitive deficit remains however to be defined.

Treatment of vaginal agenesis with vulvoperineal fasciocutaneous flaps

A simple surgical technique is reported for the treatment of vaginal agenesis utilizing vulvoperineal fasciocutaneous flaps based on the terminal vessels of the internal pudendal artery. Two vulvoperineal axial flaps are sutured together, skin surface opposed, then rotated posteriorly into rectovesical space. The operation has been performed on one patient, with good anatomic and functional results and without complications.

Hollymoor Hospital Dementia Service. Analysis of outcome of 230 consecutive referrals to a psychiatric-hospital Dementia Service

Among patients aged under 75 referred to a psychiatric-hospital dementia service the sex ratio was 1:1. In older age groups women greatly outnumbered men. More men than women were in need of institutional care, and mortality was significantly higher in men. Significantly more men than women were referred for aggressive behaviour, and significantly more women than men for paraphrenia-like symptoms. Prompt domiciliary assessment, neuroleptic treatment, and community help arranged by the dementia service enabled more than a third of patients referred to be managed at home.

Family medicine in a tertiary care hospital. Obstetrical outcomes and interventions

OBJECTIVE

To examine the rates of obstetrical complications and interventions among patients managed or comanaged by family physicians.

DESIGN

Case series. Retrospective review of hospital records.

SETTING

Victoria Hospital, a tertiary care centre affiliated with the University of Western Ontario in London, Ont.

PARTICIPANTS

Five hundred forty-two women in labour admitted consecutively by family physicians from October 1, 1990, to September 31, 1991. There were no exclusions based on antenatal risk.

MAIN OUTCOME MEASURES

Degree of risk on admission, and rates of cesarean sections, inductions, epidurals, forceps deliveries, episiotomies, perineal tears, postpartum hemorrhages, and postpartum fever for mothers. For newborns, Apgar scores and rate of need for a pediatric critical care unit or special observation nursery.

RESULTS

Except for rates of inductions and episiotomies, which were lower than those reported elsewhere, results were all comparable to those in previous North American studies of low-risk family medicine obstetric patients.

CONCLUSION

Family physicians care for women with a range of antenatal risks. Even when practising in tertiary care environments, family physicians can minimize many obstetrical interventions while maintaining good maternal and neonatal outcomes.

Family practice obstetrics in a teaching hospital. Does a tertiary care environment make a difference?

OBJECTIVE

To determine referral rates, to study the nature of consultations with obstetricians, and to examine how both patient and physician characteristics affect referrals.

DESIGN

Case series. Retrospective review of hospital records.

SETTING

Victoria Hospital, a tertiary care centre affiliated with the University of Western Ontario in London, Ont.

PARTICIPANTS

Five hundred forty-two women admitted consecutively for delivery under the care of family physicians from October 1, 1990, to September 31, 1991.

OUTCOME MEASURE

The number and types of obstetrical consultations obtained for the study population.

RESULTS

Of the 50.7% of cases requiring consultation, half were delivered by obstetricians. The most common reasons for consultation were failure to progress in labour, induction of labour, posterior presentation, fetal distress, and pregnancy-induced hypertension. The most common reasons for obstetricians to attend delivery were to perform forceps rotations and cesarean sections.

CONCLUSIONS

Parity and risk classification were the two most important factors for predicting whether consultation would occur. The high rate of consultation in this study might relate to ease of access to consultation in a tertiary care environment. More study is needed to examine the reasons for consultation because it seems that some of the situations for which obstetricians were consulted could have been safely managed by family physicians.