Cardiac arrhythmia caused by a Kirschner wire inside the heart. An unusual complication of finger osteosynthesis

A 45-year-old woman with no previous history of cardiac disease woke up one morning with an irregular heartbeat and fatigue. An electrocardiogram showed atrial fibrillation and plain chest radiographs revealed the presence of a metallic pin at the position of the heart. A 24 mm-long metallic pin was removed by open thoracic surgery from within the right ventricle of the heart. Postoperative examination of the pin showed it to be one of the 0.8 mm Kirschner wires that had been used for finger osteosynthesis in her left hand 31 months previously.     

Postnatal development of low [Mg2+] oscillations in neocortex

One form of rhythmic activity intrinsic to neocortex can be induced in slices of adult somatosensory cortex by lowering [Mg2+]o to unblock N-methyl--aspartate (NMDA) receptors. It has been suggested that a population of intrinsically burst-firing (IB) neurons that are unique to cortical layer 5 may play a role in the rhythmic activity seen under these conditions. Whole cell patch-clamp and field-potential recordings in slices of somatosensory cortex from neonatal rats were used to study the development of IB cells and the development of 0 [Mg2+] oscillations. IB cells were not encountered before postnatal day 12 (P12) in layer 5, but from P13 to P19 an increasing proportion of cells had IB properties. Recordings from cells at P7, P17, and P19 in 0 [Mg2+] indicate that dramatic changes occur postnatally in 0 [Mg2+]-induced activity. At P7, cells largely showed trains of single action potentials. In contrast, at P19, cells showed organized bursts of rhythmic activity lasting 0.5-5 s separated by periods of relative quiescence. Cells recorded at P17 were found to have less organized rhythmic activity than cells from P19 cortex. Field-potential recordings in 0 [Mg2+] made at P7 showed infrequent and slowly occurring field depolarizations, whereas field-potential recordings at P19 consisted of spontaneous bursts of 4-12 Hz oscillations identical to those observed in the adult. Application of NE, which inhibits burst-firing of layer 5 IB cells, significantly altered the discharge pattern of 0 [Mg2+] oscillations at P19. These data suggest that the maturation of one type of rhythmic network activity intrinsic to neocortex is influenced by the development of the membrane properties of a single cell type.     

A theoretical analysis of the deactivation of an immobilised enzyme in multi-enzyme reactions in fixed-bed and fluid-bed reactors

The effect of time-averaging on the selectivity to an intermediate R (yR ) and the yield to product S (yR ) in a consecutive reaction A→R→S, occurring in a deactivating fixed-bed reactor, has been examined. Time-averaging smooths the selectivity and increases the yield for high values of the deactivation (λ) and reaction (δ) parameters. The kinetics and dynamics of yR and yS in a deactivating steady-state fluid-bed reactor were also examined. Both non-selective and selective deactivation are considered. The practical implications of the development are considered in terms of an example, in which the values chosen for parameters are arbitrary though reasonable with respect to experimental values.     

ON THE INFLUENCE OF EXTERNAL DIFFUSIONAL LIMITATIONS ON OPTIMUM TEMPERATURE OPERATIONS POLICIES IN DEACTIVATING FIXED-BED REACTORS

The influence of external mass transfer limitations on optimum temperature operations policies, and on the reaction and deactivation parameters is determined for a first-order primary reaction and first-and d^th-order reactant-independent deactivation kinetics occurring in a fixed-bed reactor. This is now done using the correct optimum temperature operations criterion. The rate of temperature rise is lower when external mass transfer limitations are present compared to the diffusion-free condition. The apparent activation energy for reaction is not only different from its intrinsic value but it is also time-variant along the optimum temperature operations policy.     

Crystallization investigation of NiSi2 thin films

Recrystallizations of ion-irradiated single crystalline and polycrystalline NiSi₂ films are investigated. In the single crystalline case, the irradiated surface portion of the NiSi₂ film reorders epitaxially in a layer-by-layer manner, initiating from the remaining undamaged single crystalline NiSi₂ seed near the NiSi₂/Si interface. The irradiated polycrystal-line NiSi₂ layer recrystallizes via growth from a fixed number of existing nuclei in the layer. In both cases, the recrystallization occurs with a relatively high velocity at very low temperatures (~ 100°C) and the activation energy of the growth rate is similar (1.2 to 1.4 eV). These results reflect the metallic bonding nature of NiSi₂ and the fact that nucleation and mass transport are not required for growth from an amorphous mixture with a stoichiometric atomic composition and existing nuclei.     

Enhancement-Mode Buried-Channel $hbox{In}_{0.7} hbox{Ga}_{0.3}hbox{As/In}_{0.52}hbox{Al}_{0.48}hbox{As}$ MOSFETs With High- $kappa$ Gate Dielectrics

The operation of long- and short-channel enhancement-mode In_0.7Ga_0.3As-channel MOSFETs with high-k gate dielectrics are demonstrated for the first time. The devices utilize an undoped buried-channel design. For a gate length of 5 mum, the long-channel devices have V_t= +0.25 V, a subthreshold slope of 150 mV/dec, an equivalent oxide thickness of 4.4 +/ - 0.3 nm, and a peak effective mobility of 1100 cm²/Vldrs. For a gate length of 260 nm, the short-channel devices have V_t=+0.5 V and a subthreshold slope of 200 mV/dec. Compared with Schottky-gated high-electron-mobility transistor devices, both long- and short-channel MOSFETs have two to four orders of magnitude lower gate leakage.     

Dust-Sized High-Power-Density Photovoltaic Cells on Si and SOI Substrates for Wafer-Level-Packaged Small Edge Computers

Advancement in microelectronics technology enables autonomous edge computing platforms in the size of a dust mote (<1 mm), bringing efficient and low-cost artificial intelligence close to the end user and Internet-of-Things (IoT) applications. The key challenge for these compact high-performance edge computers is the integration of a power source that satisfies the high-power-density requirement and does not increase the complexity and cost of the packaging. Here, it is shown that dust-sized III–V photovoltaic (PV) cells grown on Si and silicon-on-insulator (SOI) substrates can be integrated using a wafer-level-packaging process and achieve higher power density than all prior micro-PVs on Si and SOI substrates. The high-throughput heterogeneous integration unlocks the potential of large-scale manufacturing of these integrated systems with low cost for IoT applications. The negative effect of crystallographic defects in the heteroepitaxial materials on PV performance diminishes at high power density. Simultaneous power delivery and data transmission to the dust mote with heteroepitaxially grown PV are also demonstrated using hand-held illumination sources.     

Dispersions of functionalized single-walled carbon nanotubes in strong acids: solubility and rheology

The manipulation and processing of single-wall carbon nanotubes (SWNTs) is limited by their poor solubility in most common solvents. Covalent sidewall functionalization of SWNTs provides an excellent route to improve their solubility. Here we have studied the relationship between sidewall functionalization and phase behavior of solutions of functionalized SWNTs (f-SWNTs) in strong acids. We use centrifugation in conjunction with UV-Vis-nlR spectroscopy to quantify the solubility of f-SWNTs in strong acids. We image the dispersions of functionalized tubes by polarized light microscopy. We find that adding butyl groups increases marginally the solubility of SWNTs in 102% sulfuric acid in the isotropic phase; adding 9-nonadecyne groups roughly doubles the solubility of SWNTs. Viscosity measurements in dilute solutions are sensitive to de-bundling. We compare the viscosity-concentration dependence of dilute pristine and f-SWNTs to assess whether and how functionalization promotes de-bundling and stabilizes the tubes. The phase behavior and rheology of these f-SWNTs parallels with that of pristine SWNTs; 9-nonadecylated SWNTs have higher solubility and should be easier to process.