ABSTRACT
We present measurements of the electronic properties of graphene using a repositionable micro four-point probe system, which we show here to have unique advantages over measurements made on lithographically defined devices; namely speed, simplicity and lack of a need to pattern graphene. Measurements are performed in ambient, vacuum and controlled environmental conditions using an environmental scanning electron microscope (SEM). The results are comparable to previous results for microcleaved graphene on silicon dioxide (SiO(2)). We observe a pronounced hysteresis of the charge neutrality point, dependent on the sweep rate of the gate voltage; and environmental measurements provide insight into the sensor application prospects of graphene. The method offers a fast, local and non-destructive technique for electronic measurements on graphene, which can be positioned freely on a graphene flake.
Subject(s)
Airway Obstruction/etiology , Trachea/injuries , Tracheal Diseases/etiology , Tracheostomy/adverse effects , Tracheostomy/instrumentation , Adult , Airway Obstruction/complications , Airway Obstruction/therapy , Bronchoscopy/methods , Diabetes Mellitus, Type 2/complications , Equipment Failure , Hemorrhage/etiology , Humans , Hypertension/complications , Male , Obesity, Morbid/complications , Pleural Effusion/complications , Postoperative Complications/etiology , Renal Insufficiency/complications , Respiration , Respiratory Insufficiency/complications , Respiratory Insufficiency/surgery , Respiratory Insufficiency/therapy , Systemic Inflammatory Response Syndrome/complications , Trachea/surgery , Tracheal Diseases/complicationsABSTRACT
Adult rats were trained on a white versus black card discrimination in a circular water tank. Three independent variables were manipulated: lesion (sham, lateral occipital, medial occipital), dose of ORG 2766 administered (0 or 25 micrograms in saline on alternate days for 18 days), and time of administration (during the post-surgical recovery interval or during post-operative testing). Both visual cortical lesions produced a prominent retention deficit and defective pattern vision. Neither post-surgical nor concurrent administration of ORG 2766 improved visual functions. These results, along with a growing body of evidence, challenge the generality of the positive influences of ORG 2766 upon behavioral recovery observed in animals with limbic lesions.
Subject(s)
Adrenocorticotropic Hormone/analogs & derivatives , Occipital Lobe/physiology , Peptide Fragments/pharmacology , Vision, Ocular/drug effects , Adrenocorticotropic Hormone/pharmacology , Animals , Behavior, Animal/drug effects , Behavior, Animal/physiology , Discrimination, Psychological/drug effects , Female , Male , Occipital Lobe/anatomy & histology , Rats , Sex CharacteristicsABSTRACT
After learning position discrimination in a T-maze water escape task, rats had either a 2 mm section of the middle cerebral artery removed bilaterally (bMCA) or they received a sham operation. Beginning on the day of surgery either total brain gangliosides (50 mg kg-1) or saline were administered daily for five days. Of the several measures of neurological function that were tested, only a temporary deficit in grasping with the front paws was observed in bMCA damaged rats. Ganglioside treatment normalized this practical function. Memory of the preoperative habit was not influenced by bMCA damage, but acquisition of a reversal of this habit was compromised. Ganglioside treatment did not influence this deficit. Acquisition of a spatial alternation strategy was influenced by neither the bMCA lesion nor the ganglioside treatment. The preservation that accompanies bMCA interruption might serve as a useful model of the functional declines that accompany stroke and frontal lobe damage.
