Three-terminal devices to examine single molecule conductance switching

We report electronic transport measurements of single-molecule transistor devices incorporating bipyridyl-dinitro oligophenylene-ethynylene dithiol (BPDN-DT), a molecule known to exhibit conductance switching in other measurement configurations. We observe hysteretic conductance switching in 8% of devices with measurable currents, and find that dependence of the switching properties on gate voltage is rare when compared to other single-molecule transistor devices. This suggests that polaron formation is unlikely to be responsible for switching in these devices. We discuss this and alternative switching mechanisms.Comment: 5 pages, 4 figures. Supporting material available upon reques

Course variability of the atlantic (V3) segment of vertebral artery: anatomical study with clinical implications

Background: The atlantic segment of vertebral artery (V3) located at the centre of the cranio-vertebral junction is known for its variability and asymmetry, and is either the target or on the way of numerous procedures in this region. The aim of the study was to visualise variability of V3 segment. Materials and methods: The V3 segment was studied in 49 specimens of the suboccipital region injected with coloured gelatine. Direct measurements were performed and probabilistic maps were created using digital photography. Results: The V3 segment has wavy course with possible lateral and significant postero-inferior expansions. In relation to the foramen transversarium the V3 reached up to 5 mm laterally, 23 mm posteriorly, 27 mm medially and up to 11 mm downward. Looking from the medial aspect the course of the V3 is less predictable compared to the lateral approach. Linear measurements and probabilistic maps revealed significant variability and large range of variation. There were 11 cases of V3 tortuosity found in studied material. Conclusions: The complex and variable spatial conformation of V3 makes individual diagnostic and preoperative approach necessary

Controlling charge injection in organic field-effect transistors using self-assembled monolayers

We have studied charge injection across the metal/organic semiconductor interface in bottom-contact poly(3-hexylthiophene) (P3HT) field-effect transistors, with Au source and drain electrodes modified by self-assembled monolayers (SAMs) prior to active polymer deposition. By using the SAM to engineer the effective Au work function, we markedly affect the charge injection process. We systematically examine the contact resistivity and intrinsic channel mobility, and show that chemically increasing the injecting electrode work function significantly improves hole injection relative to untreated Au electrodes.Comment: 5 pages, 2 figures. Supplementary information available upon reques

Median aperture of the fourth ventricle revisited

Background: The median aperture of Magendie is the largest of three openings of the fourth ventricle and thus it forms the main path for the outflow of the cerebrospinal fluid from the ventricle. The Magendie aperture connects the fourth ventricle with the cisterna magna and makes a natural corridor for neurosurgical approach and inspection of the ventricle and its floor. The purpose of this study was to give a contemporary anatomical view of this structure in the context of historical data. Material and methods: The Magendie foramen was studied in 30 fixed specimens of human brainstems with cerebella. The microdissection technique was used. Measurements were taken with a microscope ocular ruler. Results: The aperture is limited by the following structures: obex and gracile tubercles inferiorly, and tela choroidea with choroid plexus superolaterally. Obex tubercles usually have the form of a piece of neural tissue bridging two halves of the brainstem above the entrance to the central canal. Gracile tubercles together are 8.15 mm wide and the maximal width of the foramen is 6.53 mm. Tela choroidea attaches laterally at both sides to the inferior medullary velum. In most cases the right and left choroid plexus are connected to each other with a triangular membrane of tela choroidea, which protrudes through the median foramen and attaches to the vermis at a highly variable level. Conclusions: We hope that the presented description of anatomical relations around the Magendie aperture, with its new measurements, will be helpful for those operating in the area and will explain some of the inaccuracies found in literature. (Folia Morphol 2011; 70, 2: 84–90

30P Nowa fizyczna metoda wczesnego diagnozowania i monitorowania leczenia chorych z rozpoznaniem nowotworu

Pole magnetyczne o indukcji B > 10 tesli znajduje zastosowanie w analizie indukowanej dwójłomności kołowej surowicy krwi. Analiza oddziaływania silnego pola magnetycznego i elektromagnetycznego pola wiązki świetlnej z surowicą krwi wykazała, że w silnym polu magnetycznym ujawnia się wyraźnie ilościowa różnica magneto-optycznych efektów obserwowanych dla surowic dawców krwi chorych z nowotworami. Dokonano analizy 110 surowic krwi. Pomiary wykonano w silnym impulsowym (B ≅ 30 tesli). Próbki surowicy 23 dawców krwi zostały poddane badaniom mającym na celu określenie naturalnej aktywności optycznej. Surowice te stanowiły punkt odniesienia do analiz surowic chorych onkologicznych. Analizowano surowice chorych z rozpoznaniem raka prostaty, jelita grubego, raka jajnika, w którym w trakcie leczenia oznacza się poziom markerów nowotworowych. Druga grupa chorych to pacjenci z mierzalnymi guzami gruczołu piersiowego, mięsaka, czerniaka, szpiczaka. Dokonano pomiarów magneto-optycznych współczynników a, b, c oraz naturalnej aktywności optycznej α0 surowic.Wykazano wyraźną współzależność między stanem chorego, a wartością współczynnika b oraz jego korelacją ze wzrostem poziomu markerów nowotworowych lub wielkością ognisk przerzutowych. Prowadzone po raz pierwszy badania magnatyczno-optycznej dwójłomności kołowej surowicy są szybką metodą analityczną. Mogą w przyszłości mieć zastosowanie w diagnostyce i monitorowaniu leczenia nowotworów

The study of arterial anastomoses in the region of the alveolar process and the anterior maxilla wall in foetuses

The anterior maxilla wall and alveolar process are covered by the arterial network. Procedures in this region can cause heavy bleeding. Knowledge of the anatomical course of a particular artery is essential for performing surgery in this area. The aim of this study was to search for and then analyse anastomoses between the infraorbital and posterior superior alveolar artery. In the study, 19 maxillas of foetuses were analysed. The arteries were injected with coloured latex. The dissection was carried out using a surgical microscope and microsurgical equipment. The lower eyelid with cheek skin was separated and the facial muscles were cut to expose the maxilla and arteries of the alveolar process. The study revealed that in 10 out of 19 of the specimens there was an arterial connection between the infraorbital and posterior superior alveolar artery. The course of the analysed anastomosis was diverse. In all cases we observed an anterior superior alveolar artery. In all specimens the alveolar process was vascularised by many arteries originating from the analysed anastomosis. The location of the analysed anastomosis can be stated before operation, on the line between the medial eye angle and the sixth tooth of the same side. The anastomosis described in the study means that caudally running arteries are important in choosing incisions in procedures performed at the alveolar process

The anatomy of the fundic branches of the stomach: preliminary results

The fundic branches of the stomach can be defined as a group of vessels that can arise either directly or indirectly from the following source arteries: the left inferior phrenic artery, the accessory left hepatic artery, the left gastric artery, the left middle suprarenal artery, the main trunk of the splenic artery, the posterior gastric artery, the superior polar artery, the gastrosplenic artery, the left gastroepiploic artery and the splenic artery with its inferior and superior terminal branches. It is worth mentioning that the fundic branches of the left gastroepiploic artery and the superior and inferior terminal branches of the splenic artery, like other vessels arising from these three source arteries and supplying the stomach, are defined as short gastric arteries. The anatomy of these fundic branches, particularly relevant to some surgical procedures, is not sufficiently described, and the current literature suffers from lack of publications on this particular topic. We therefore decided to explore in detail the arterial vascularisation of the gastric fundus. The research was carried out on material consisting of 15 human stomach specimens. The anatomical analysis comprised the following: the number of occurrences of fundic branches in each of the source arteries defined above, the distance between the origins of the source artery and its arising fundic branch, the way in which the fundic branches arose, the length, diameter at point of origin and morphology of the fundic braches, as well as the exact point of perforation of each fundic branch on the fundus. The highest incidence of the direct-branching pattern of fundic branches was in the left middle suprarenal artery, the gastrosplenic artery and the left gastrosplenic artery. The accessory left hepatic artery, the left gastric artery and the main trunk of the splenic artery were the most frequent site of the indirectly arising pattern of fundic branch. The highest median value of fundic branch length was 63.05 mm, found in the accessory left hepatic artery group. The largest median diameter value of the vessel was encountered among those originating in the left middle suprarenal artery and reached 2.17 mm. The posterolateral quadrant of the fundus received the largest number of fundic branches, amounting to 46.5% of all the fundic branches studied. (Folia Morphol 2008; 67: 120–125

Radiological anatomy of the ambient cistern in children

Ambient cistern (AC) is a thin extension of the subarachnoid space surrounding the brainstem at the level of the mesencephalon and pons. Despite various definitions, it constitutes an important landmark in clinical assessment of intracranial volume reserve. Although it is indisputably useful, there exists no defined standard for radiological examination for the dimensions and ranges in specific age groups. This paper aims to describe the ambient cistern anatomically and give the ranges of dimensions for proper radiological interpretation. The study was performed on 160 axial computed tomography (CT) examinations of Polish children of both sexes, aged 1-18 years, admitted to the hospital because of mild brain concussion. Pictures were made using a Siemens 8-row CT scanner, without contrast administration. We estimated distances at the level of the pons and midbrain, based on axial cross-sections, according to standard radiological protocol. The parameters included the width of the AC in its anterior and posterior part, the width of the tentorial notch, and the distance from the pons and sella. All measurements were analyzed statistically with StatSoft Statistica 8.0 software. The average width of the AC differs between age groups. It is greatest at 1-3 years (2.8 ± 0.6 mm) and lowest at 4-10 years (2.4 ± 0.6 mm). AC is more likely to be greater in its anterior part in boys. The distance from the sella to the pons is greatest in 1-3-year-old girls (6.9 ± 1.3 mm), and the tentorial notch is widest in the 15-18-year-old group (24.6 ± 2.4 mm). Dimensions of the AC correlate with intracranial reserve volume. This is particularly visible in the youngest children. Thin and narrow AC is not always a sign of raised intracranial pressure. It may be specific for the child’s age. (Folia Morphol 2010; 69, 2: 78-83

Kondo resonances and anomalous gate dependence of electronic conduction in single-molecule transistors

We report Kondo resonances in the conduction of single-molecule transistors based on transition metal coordination complexes. We find Kondo temperatures in excess of 50 K, comparable to those in purely metallic systems. The observed gate dependence of the Kondo temperature is inconsistent with observations in semiconductor quantum dots and a simple single-dot-level model. We discuss possible explanations of this effect, in light of electronic structure calculations.Comment: 5 pages, four figures. Supplementary material at http://www.ruf.rice.edu/~natelson/publications.htm

Uncommon branching pattern of the hepatic arteries in a living donor: a case report and brief literature review

Numerous variations of the hepatic arteries are common in surgical patients. We present a 35-year-old woman who was admitted to our department in order to assess possibility of becoming living donor. Preoperative computed tomography scan revealed anomalous branching pattern of the hepatic arteries. In this case right posterior sectoral artery has been given off by the greater pancreatic artery, left hepatic artery has been replaced by the artery arising from the left gastric artery and double segment 4 branches have been observed. To the best of our knowledge, this pattern has not been described in the literature, yet