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In recent years, circular saw blades with thinner kerfs have been in high demand for improvement of the production yield of wood-based materials and the reduction of sawdust. In the case of ripping of solid wood, the number of teeth of a circular saw blade is normally set to 40 or 50, with a diameter of 305 mm, which allows less cutting resistance and smooth exhausting of sawdust. However, at certain rotational speeds, self-excited alternate-tooth vibration can easily occur in circular saw blades with such thin kerfs and so few teeth. Therefore, the cutting surface quality tends to be worse. In this study, the mechanism of this self-excited alternate-tooth vibration was clarified. The vibration mode and frequency were predicted by the finite element method. In addition, a circular saw blade with a body thickness 1.5 mm and 50 teeth was employed for wood-cutting experiments. The rotational speed range of the self-excited alternate-tooth vibration modes and their frequencies were investigated. When a double of the tooth passage frequency was slightly higher than the frequencies of the alternate-tooth vibration modes, an alternate-tooth vibration of the regenerative chatter type was excited, owing to the forces on the sides of the tooth.

Hyponatraemia is defined as a serum sodium concentration of

Machining aspects with helical edge router bits (helix angle 15°, 30°, 45°, and 60°) with a cutting circle diameter of 8 mm were studied. The purpose of the research work was to investigate chip formation and surface roughness characteristics in milling pine wood by the straight and helical edge bits. The chips generated could be classified into four types by sieving into spiral chip (5 mesh), flow chip (10 mesh), thin chip (30 mesh), and granule chip (

Tribological properties of textured surfaces fabricated using a discontinuous microcutting process were investigated. Aluminum cast alloy (AC8A) discs were used for the specimens. The texturing process was carried out using a CNC machining center with a cutting edge with a novel geometry. The resulting surface morphology consisted of micro dimples with a diameter of 200-300 μm and a depth of 5-10 μm, with controlled area fractions of 10 and 40% and a top region finished with a milling cut. The tribological properties were evaluated using a ring-on-disc type testing apparatus under lubricated conditions, and showed that the friction coefficient of the textured surfaces was low and stable from the beginning of the experiment. A dependence of the friction coefficient on the area fraction was also found. Further reductions in the friction coefficient were achieved on a textured surface with a polished top region. It can be concluded that the proposed discontinuous micro cutting process is an effective means of fabricating a micro texture for the reduction and stabilization of frictional resistance.

Increased re-hospitalization due to acute decompensated heart failure (ADHF) is a modern issue in cardiology. The aim of this study was to investigate risk factors for re-hospitalization due to worsening heart failure, and the effect of tolvaptan (TLV) on decreasing the number of re-hospitalizations. This was a multicenter, retrospective study. The re-hospitalization factors for 1191 patients with ADHF were investigated; patients receiving continuous administration of TLV when they were discharged from the hospital (n = 194) were analyzed separately. Patients were classified into 5 risk groups based on their calculated Preventing Re-hospitalization with TOLvaptan (Pretol) score. The total number of patients re-hospitalized due to worsening heart failure up to one year after discharge from the hospital was 285 (23.9%). Age ≥80 years, duration since discharge from the hospital after previous heart failure 7.2 mg/dl, left ventricular ejection fraction (LVEF) 44.7 ml/m2, loop diuretic dose ≥20 mg/day, hematocrit

Background— In patients with mechanical aortic and mitral valves and left ventricular tachycardia, catheter ablation may be prevented by limited access to the left ventricle. Methods and Results— In our series of 6 patients, 2 patients underwent direct surgical ablation and 4 underwent epicardial catheter ablation via a pericardial window. All patients had abnormal low voltage areas with fractionated or delayed isolated potentials on the apical epicardium. Most of the ventricular tachycardias were targeted by pace mapping. Sites with a good pace match or abnormal electrograms were ablated using an irrigated radiofrequency ablation catheter. A microscopic pathological evaluation of the resected tissue from 2 of the open-heart ablation patients revealed dense fibrosis on the epicardium compared with the endocardium, supporting the feasibility of an epicardial ablation for the ventricular tachycardia. Conclusions— Epicardial catheter ablation of ventricular tachycardia is a potentially useful therapy in patients who have mechanical aortic and mitral valves.

Reactive oxygen species (ROS) are the main facilitators of cardiovascular complications in diabetes mellitus (DM), and the ROS level is increased in cultured cells exposed to high glucose concentrations or in diabetic animal models. Emerging evidence shows that mitochondria and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase are dominant mechanisms of ROS production in the diabetic heart. Hyperpolarization of the mitochondrial inner membrane potentials and impaired mitochondrial function promote ROS production in the mitochondria of the diabetic heart. Uncoupling proteins are upregulated and may reduce the ROS level by depolarizing the mitochondrial inner membrane potential. NADPH oxidase is another major site of ROS production and its contribution to DM-induced ROS increase has been elucidated not only in vascular smooth muscle cells and endothelial cells, but also in cardiomyocytes. Protein kinase C, angiotensin II, and advanced glycation endproducts (AGEs)/receptor for AGEs can activate NADPH oxidase. Increased intracellular calcium level mediated via the Na(+)-H(+) exchanger and subsequent activation of Ca(2+)/calmodulin-dependent protein kinase II may also activate NADPH oxidase. This review presents the current understanding of the mechanisms of ROS production, focusing especially on the roles of mitochondria and NADPH oxidase.

A 54-year-old male patient presented with a symptomatic bifurcation lesion of 75% stenosis in LAD ([Figure 1A][1]). Physiological evaluation was performed using instantaneous wave-free ratio (iFR) roadmap (Philips Healthcare, Best, the Netherlands) functionality [(1)][2]. First, we ran a

BACKGROUND AND PURPOSE Resveratrol is a polyphenol abundantly found in grape skin and red wine. In the present study, we investigated whether resveratrol exerts protective effects against cardiac ischaemia/reperfusion and also explored its mechanisms. EXPERIMENTAL APPROACH Infarct size and functional recovery in rat isolated perfused hearts subjected to no-flow global ischaemia followed by reperfusion were measured. Cultured neonatal rat cardiomyocytes were exposed to H(2)O(2) (100 µmol·L(-1)) to induce cell injury. Intracellular ion concentrations were measured using specific dyes. Western blotting was used to quantify protein expression levels. KEY RESULTS In rat isolated perfused hearts, treatment with resveratrol (20 and 100 µmol·L(-1)) 15 min before ischaemia considerably improved left ventricular functional recovery and infarct size. In cultured neonatal rat cardiomyocytes, resveratrol significantly attenuated the increase in reactive oxygen species (ROS) and loss of mitochondrial inner membrane potential. Resveratrol also suppressed the increase in intracellular concentrations of Na(+) ([Na(+)](i)) and Ca(2+) ([Ca(2+)](i)) after H(2)O(2) application; however, it did not suppress the ouabain-induced [Ca(2+) ](i) increase. By measuring changes in intracellular pH recovery after acidification, we also confirmed that acid-induced activation of the Na(+)-H(+) exchanger (NHE) was prevented by pretreatment with resveratrol. Furthermore, resveratrol inhibited the H(2)O(2)-induced translocation of PKC-α from the cytosol to the cell membrane; this translocation is believed to activate NHE. CONCLUSION AND IMPLICATIONS Resveratrol exerts cardioprotection by reducing ROS and preserving mitochondrial function. The PKC-α-dependent inhibition of NHE and subsequent attenuation of [Ca(2+)](i) overload may be a cardioprotective mechanism.

Diabetes mellitus is a risk factor for heart failure. Increased reactive oxygen species (ROS) have been proposed as a possible mechanism of cardiac dysfunction in diabetic patients. However, the mechanisms of ROS increase are still elusive. We hypothesized that activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) induced by impaired intracellular Ca(2+) ([Ca(2+)](i)) metabolism may stimulate ROS production in the diabetic heart. Cultured cardiomyocytes from neonatal rats were exposed to high glucose concentrations (25 mmol/L) and ROS levels were analyzed in 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H(2)DCFDA)-loaded cells by flow cytometry analysis. Exposure to high glucose concentrations for 24h significantly increased CM-H(2)DCFDA fluorescence, which was significantly inhibited by 1,2-bis (o-aminophenoxy) ethane- N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester (BAPTA-AM), a [Ca(2+)](i) chelator, and KB-R7943, an inhibitor of the Na(+)-Ca(2+) exchanger (NCX) in the reverse mode. These results indicate that [Ca(2+)](i) increase by NCX activation may induce ROS increase following exposure to high glucose concentrations. We confirmed that exposure to high glucose concentrations significantly increased [Ca(2+)](i), which was inhibited by KB-R7943. Na(+)-H(+) exchanger (NHE) is a key factor in [Ca(2+)](i) metabolism, and is known to activate NCX by increasing the intracellular Na(+) ([Na(+)](i)) level. We showed that the expression of NHE isoform 1 and NHE activity increased following exposure to high glucose concentrations by evaluating protein expressions and intracellular pH recovery from acid loading. Exposure to high glucose concentrations up-regulated phosphorylated CaMKII expression in cardiomyocytes that was inhibited by KB-R7943. Further, autocamtide 2-related inhibitory peptide (AIP), a CaMKII inhibitor, significantly attenuated the ROS increase following exposure to high glucose concentrations. We confirmed these results obtained in in vitro experiments in an animal model of diabetes. ROS level and components of NADPH oxidase, p47phox and p67phox were up-regulated in streptozotocin-induced diabetic rat heart, which were attenuated by KN-93, a CaMKII inhibitor. Consistently, expression of phosphorylated CaMKII was increased in the diabetic heart. Activation of CaMKII by impaired [Ca(2+)](i) metabolism may be a mechanism of ROS increase in the heart with diabetes mellitus.

Using the PVD arc ion plating method, Cr-B-N, Cr-C-N, and Cr-O-N coatings with different B, C, and O contents, and CrN coatings were prepared. Their microstructures and some properties were also investigated.X-ray diffraction measurements revealed that all the coatings have the NaCl type cubic CrN phase. Other phases such as boride, carbide, and oxide were not detected. Because of the addition of the third element to the CrN coating, the diffraction peaks shifted to a lower angle and the peaks broadened.As the amount of the third element increased, hardness of Cr-B-N, Cr-C-N, and Cr-O-N coatings increased because the grain sizes became smaller and the compressive residual stresses increased. Results showed that, even with small amounts, the addition of B had the greatest influence on high hardness and high residual stress.TEM observations revealed that the CrN coating has a dense columnar microstructure, and that the addition of the third element makes the grain sizes smaller than that of the CrN coating. Results show that the Cr-B-N coating has the smallest grains, and that the fine microstructure exhibits good correlation with its properties.

Nanoparticles of the insoluble organic compound 3,4,9,10-perylenetetracarboxylicdianhydride were prepared by nanosecond pulsed laser irradiation of microcrystalline solid suspensions in polar solvents using the 3rd harmonic (355 nm) from a Nd:YAG laser. The initially cloudy suspensions became transparent clear red dispersions that passed through a 0.2 μm membrane filter 1 day after 30 min of irradiation at laser fluences greater than 130 mJ cm−2. Filtering reduced the red color indicating that it originated from light absorption by particles or aggregates with a size range spanning the 0.2 μm filter cut-off. This is consistent with scanning electron microscope images. Whether or not the particles passed through the filter depended on how long they were aged. Initially formed dispersions did not pass through, whereas those which had been aged for several hours did, indicating that the nanoparticles were aggregated and that the aggregate size depended on the standing time after laser irradiation. HPLC analysis revealed perylene and C8, C10, C12, C14 polyynes byproducts, which probably formed respectively in a 3 photon photochemical and a photothermal processes at the surface of the PTCDA particles. Initially the perylene production rate was rapid, but as the PTCDA particles’ surface became decomposed it slowed down. However, it increased again as the surface area of the PTCDA particles became larger as smaller nanoparticles formed and after the thermal decomposition of the surface was quenched. When the particles became smaller the thermal processes were quenched and polyyne production stopped.

Deposited films were prepared by ablation of disk-like targets of 3,4,9,10- perylenetetracarboxylic dianhydride (PTCDA) and mixed targets of PTCDA with cobalt (PTCDA-Co) and copper powders (PTCDA-Cu) using the third harmonic of a Nd:YAG laser (355 nm) at fluences ranging from 0.1 to 1.0 Jcm−2pulse−1. FT-IR and Raman spectroscopy showed that ablation of PTCDA-Cu at more than 500 mJcm−2pulse−1 led to an effective elimination reaction of the anhydride groups of PTCDA as well as PTCDA-Co at more than 700 mJcm−2pulse−1. In ablation of PTCDA-Co and PTCDA-Cu, plasma emission was observed around 500 nm. With increasing fluence, addition to the plasma emission, peaks at 437, 469, 513 and 550 nm coming from C2 radicals were observed, suggesting that PTCDA was partially decomposed into C2. TOF mass spectra in ablation of PTCDA-Co showed fragments of PTCDA without one or two anhydride groups as well as CoCn+ (n = 0-5) and Co (CO)2+.

Background The influence of glucose fluctuations (GF) on cardiovascular complications of diabetes mellitus (DM) has been attracting much attention. In the present study, whether GF increase susceptibility to ischemia/reperfusion in the heart was investigated. Methods and results Male rats were randomly assigned to either a control, DM, and DM with GF group. DM was induced by an injection of streptozotocin, and glucose fluctuation was induced by starvation and insulin injection. One sequential program comprised 2 hypoglycemic episodes during 4 days. The isolated hearts were subjected to 20-min ischemia/30-min reperfusion. The infarct size was larger in hearts with GF than those with sustained hyperglycemia. Activities of catalase and superoxide dismutase were decreased, and expressions of NADPH oxidase and thioredoxin-interacting protein were upregulated by GF accompanied by an increase of reactive oxygen species (ROS). Swollen mitochondria with destroyed cristae were observed in diabetic hearts; they were further devastated by GF. Microarray analysis revealed that the expressions of microRNA (miRNA)-200c and miRNA-141 were abundant in those hearts with GF. Overexpression of miRNA-200c and miRNA-141 decreased mitochondrial superoxide dismutase and catalase activities, and increased ROS levels. Meanwhile, knockdown of miRNA-200c and miRNA-141 significantly decreased ROS levels in cardiomyocytes exposed to GF. Conclusions GF increased ROS generation and enhanced ischemia/reperfusion injury in the diabetic heart. Upregulated miRNA-200c and miRNA-141 may account for the increased ROS.

The structures of self-assembled monolayers of dioctadecyl selenide (CH 3 (CH 2 ) 1 7 ) 2 Se and dioctadecyl telluride (CH 3 (CH 2 ) 1 7 ) 2 Te, as well as dioctadecyl ether (CH 3 (CH 2 ) 1 7 ) 2 O and dioctadecyl sulfide (CH 3 (CH 2 ) 1 7 ) 2 S, on graphite at the liquid-solid interface were systematically investigated by scanning tunneling microscopy (STM). Both dioctadecyl selenide and telluride formed monolayer structures in which the tilt angle between the molecular axis of the alkyl chain and the lamellae axis was 90", while dioctadecyl ether assembled with a tilt angle of 60°. Dioctadecyl sulfide was found to make two different self-assembled structures having tilt angles of 60 and 90°. When selenide was embedded in ether compounds in mixed self-assembled monolayers, the alkyl chains of the selenide became blurred, implying that the alkyl chains in the monolayers were unstable. This is in contrast with the structure of co-adsorbed monolayers of the ether and sulfide compounds, where the imaggs, of all alkyl chains had high spatial resolution. For the co-adsorbed monolayers, the image contrast of chalcogen atoms was normalized compared with that of alkyl chains of the ether compound in the same image frame. The normalized image contrast was found to be independent of the measurement conditions involving tip shapes, having the following trend, Te>Se>S>C>O. The difference in the normalized image contrast among chalcogen atoms are discussed based on fundamental parameters like polarizability and atomic radii.

Two kinds of self-assembled structures of 1-pyrenehexadecanoic acid at a solution-graphite interface were investigated using scanning tunneling microscopy. The pyrenyl groups of 1-pyrenehexadecanoic acid formed a π-stacked assembly when it was co-adsorbed with 4,4′-dipyridyl although the pyrenyl groups remained isolated in the one-component self-assembled structure. On the basis of the Davidov splitting model, the shift of the pyrenyl group’s electronic levels, upon formation of the π-stacked assembly, was estimated from the observed structures. The energy shift was found to be consistent with the observed change in the electron-tunneling spectra between these two different structures.

従来の心電図内高周波電位の検討はQRS後半の電位を対象として解析されていたが, QRS区間内の高周波成分に関してはいまだ十分な検討がなされていない.そこで, 時間・周波数分解能に優れたwavelet解析法を用いて健常者および心筋梗塞患者のQRS区間内高周波成分を比較検討することを目的とした.健常者例, 心筋梗塞例の体表面からフランク誘導を用いてX, Y, Z双極誘導で心電信号を導出し, 得られた心電図信号をsubtraction法で濾波を行った後, wavelet解析を行った.孤立した高周波成分 (不連続点) は健常者群ではX誘導に, 下壁心筋梗塞患者群はY誘導に, 前壁中隔心筋梗塞患者群はZ誘導に多く認められた.これより心筋梗塞では健常者に比較して周波数系列において不連続点を生じ, さらに梗塞部位近傍の誘導に多く認められる傾向にあった, よって, 心筋梗塞では心筋興奮が一様ではなく固有の高周波成分が出現していることが示唆された

Density functional calculations at the B3LYP/6-31G* level were performed for perylene tetracarboxylic dianhydride (PTCDA) and its potential derivatives modified by replacing the two anhydride ether groups with B-, N-, S-, and Se-containing groups, as well as for perylene monomer and dimer structures. The predicted infrared (IR) and Raman spectroscopic properties of PTCDA have been compared with the observed experimental spectra and available theoretical data. In addition, the isotope effect on the Raman and IR spectra of PTCDA by the replacement of all H atoms by deuterium isotopes, as well as the estimated UV-vis properties of PTCDA and its modified derivatives, based on the results of the time-dependent DFT method have been also presented. It was shown that the formation of polyperinaphthalene films affects strongly the predicted theoretically IR, Raman and UV-vis spectra of the precursor PTCDA. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

Polyperinaphthalene (PPN) nanoparticles are prepared by excimer laser ablation (ELA) of a 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) target or a mixture target of PTCDA with Co or TiO2 powder (PTCDA/X: X=Co, TiO2) using XeCl excimer laser beams. Enhancement of elimination reaction of side groups of PTCDA is observed by ELA of PTCDA/Co and PTCDA/TiO2. In particular, for PTCDA/TiO2, the reaction occurs at a fluence of 0.25 J cm−2 pulse−1 much lower than the case of PTCDA/Co at room temperature. Heterojunctions between the PPN nanoparticle layer and Si wafers are formed. Well rectifier property is demonstrated for the junction with n-Si substrates. Current versus voltage curve of the heterojunction with a n-Si substrate in the dark and under illumination shows the possibility of the junction as a photovoltaic cell. Furthermore, PPN nanoparticles are applied to anode electrodes for ultrathin rechargeable Li ion batteries. In situ Raman spectroscopy under lithium ion doping is performed to elucida...

Films are deposited on substrates at 20 °C by excimer laser ablation (ELA) of mixture targets of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with metal powder, PTCDA/M (M=Co, Ni, Fe, W, Cu and Ag) using XeCl and ArF beams. Large amount of fragments with “naked” perylene skeletons can be produced owing to effective elimination of carboxylic dianhydride groups by ELA of PTCDA/Co both with XeCl and ArF beams under optimized ablation conditions. Elimination reaction of side groups of PTCDA is observed for ELA of the targets with metal powder of the iron group, Co, Fe and Ni, especially remarkable for Co and Fe. The film from PTCDA/Ni consists of small particles with the various diameters ranging from 10 to 100 nm as well as that from PTCDA/Co. Morphology like petal of rose can be seen everywhere for the film from PTCDA/Fe.

Polyperinaphthalene (PPN) thin films are prepared by excimer laser ablation (ELA) of a 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) target or a mixture target of PTCDA with Co or TiO2 powder (PTCDA/X: X=Co, TiO2) using XeCl excimer laser beams. Enhancement of elimination reaction of side groups of PTCDA is observed by ELA of PTCDA/Co and PTCDA/TiO2. In particular, for PTCDA/TiO2, the reaction occurs at a fluence of 0.25Jcm-2pulse-1much lower than the case of PTCDA/Co at room temperature. Heterojunctions of PPN films prepared by ELA of PTCDA with Si wafers are fabricated. Well rectifier property is obtained for the junction of the PPN with a n-Si substrate. Current versus voltage curves of the heterojunction in the dark and under illumination show that the junction is promisimg as a photovoltaic cell. Furthermore, PPN films are applied to anode electrodes for ultra thin rechargeable Li ion batteries. Substrate temperature dependence ofeffective capacitance of lithium ions at first cycle are investigated. In addition, in-situ Raman spectroscopy of the films under lithium ion doping and undoping is performed to elucidate the storage mechanism of lithium ion at cis-polyacetylene-type edge (phenanthrene-edge) of PPN structure.

Aims We investigated whether glucose fluctuations aggravate cardiac fibrosis and increase the occurrence of atrial fibrillation (AF) in rats with diabetes mellitus (DM). Methods and results Streptozotocin-induced diabetic rats were randomly divided into three groups: uncontrolled DM (U-STZ) group, controlled DM (C-STZ) group, and DM with glucose fluctuations (STZ-GF) group. Glucose fluctuations were induced by fasting for 24 h and additional regular insulin injections (0.5 IU/kg) administered three times per week for three consecutive weeks. C-STZ rats were administered long acting insulin (20 IU/kg) twice a day to control blood glucose levels. Cardiac fibrosis evaluated by Masson trichrome staining and the expressions of collagen type 1, collagen type 3, and α-smooth muscle actin were increased in U-STZ rats compared with C-STZ rats, which were more pronounced in STZ-GF rats. The inducibility of AF was significantly larger in U-STZ rats than C-STZ rats and was greatest in STZ-GF rats. To explore the mechanism of cardiac fibrosis, we investigated the levels of reactive oxygen species (ROS) and apoptosis. The expression of malondialdehyde, an indicator of ROS levels, was significantly upregulated in STZ-GF rats compared with U-STZ rats, along with increased thioredoxin-interacting protein (Txnip) expression in STZ-GF rats. Furthermore, caspase-3 expression and the number of TUNEL-positive cells were significantly increased in STZ-GF rats compared with U-STZ and C-STZ rats. Conclusion Glucose fluctuations increase the incidence of AF by promoting cardiac fibrosis. Increased ROS levels caused by upregulation of Txnip expression may be a mechanism whereby in glucose fluctuations induce fibrosis.

Polymer laser photochemistry is reviewed. Mechanisms of laser ablation of polymers have been extensively studied. The photolytic/photothermal issue has been one of the targets of hot arguments. Post-ionization analyses of ablated fragments with multi-photon ionization/time-of-flight (TOF) mass spectrometry have been very useful. Laser light has been conveniently utilized in the chemical surface modification of polymers. Reconstructed polymer films have been prepared by the excimer laser ablation of polymers, followed by the deposition onto another substrate. The composition of reconstructed polymer films was highly dependent on the wavelength and/or fluence of the laser light. Laser-induced polymerization has been performed by excimer laser ablation of solid monomers like 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) onto another substrate. Semi-conductive polymer films were prepared. Polymerization by laser-assisted deposition is a CVD-like technique for the preparation of polymers, applied to gaseous monomers, like polythiophene from thiophene.

Excimer laser ablation (ELA) of 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) with ArF (193 nm), KrF (248 nm), XeCl (308 nm), and XeF (351 nm) beams under optimized conditions enables us to obtain organic semiconductor thin films with various structures such as amorphous carbon, polyperinaphthalene (PPN), and PTCDA itself. Electric conductivity and carrier species of the films depend strongly on the ablation wavelength, fluence, substrate temperature, and ambient vapor species. It is found that electric conductivities of the films are controllable, ranging from 10-6 to 101 S cm-1 with the selection of appropriate ablation conditions. An organic pn junction is successfully constructed by the change of ablation conditions during ELA. Furthermore, ELA of PTCDA at 248 nm in iodine vapor leads to formation of tetraiodoallene in the film.

Reactions of monopositive metal ions (Al + , Co + and Mn + ) with ammonia–acetone binary clusters in the gas phase have been studied with the laser ablation-molecular beam (LAMB) method. Relative abundance of the resulting metal complex ions M + (NH 3 ) m (CH 3 COCH 3 ) n (M + =Al + , Co + , Mn + ) has been probed for several stagnation ratios of NH 3 /CH 3 COCH 3 /Ar. The relative abundance for the same stagnation ratio was highly metal-specific, indicating occurrence of complete reorganization during the reactions. Structures of the metal complex ions are discussed based on the metal-specific pattern of the relative abundance.

Violet-colored 2,3,4,5-tetraphenylpyrrolyl radicals (TPPRs) were remarkably long-lived (more than 10 h) in benzene solution at room temperature. Their decay obeyed the second-order kinetics; two TPPRs recombine to form a colorless dimer. The temperature dependence of the recombination rate was close to that of the reciprocal of solvent viscosity, precluding the presence of any additional activation barrier for the recombination reaction apart from that imposed on the encounter of radicals by solvent viscosity; the rate is limited solely by the steric factor. Although TPPRs come across many times by diffusion, four outspread phenyl groups limit the useful approach of the reactive sites that are on the pyrrolyl ring. In most cases, TPPRs form the nonreactive random encounter radical pair (RERP), which separates again with the diffusion rate. The reactive RERP is formed only when TPPRs approach each other with their reactive sites exactly facing each other. Useful approach is limited to only a small “favorable” solid angle, resulting in the partially diffusion-controlled recombination. A significant retarding effect caused by the external magnetic field was observed on the recombination reaction of the reactive RERP. The effect was not saturated up to 0.5 T and can be explained by the relaxation mechanism with the underlying hyperfine coupling mechanism.

Amorphous organic semiconductive thin films with electric conductivities ranging between 10−5 and 101 Scm−1 are prepared on several temperature-controlled substrates by excimer laser ablation (ELA) of 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) with 193 nm (ArF), 248 nm (KrF) and 308 nm (XeCl) beams. The structure, electric conductivity, and carrier species of the prepared films depend strongly on the ablation wavelength, fluence, and substrate temperature. Thermoelectromotive force measurements demonstrate conversion of carrier species from n-type to p-type with increasing fluence of a 308-nm beam from 0.2 to 4.0 Jcm−2pulse−1. A film prepared on a substrate at 300 °C by ELA with a 308-nm beam partially contains a polyperinaphthalene (PPN) structure with electric conductivity of 10−2 to 10−1 Scm−1. © 1998 Scripta Technica, Electr Eng Jpn, 125(2): 19–26, 1998

Polythiophene thin films are prepared by UV laser-assisted deposition (UV-LAD) of 2,5-dichlorothiophene (2,5-DCT) with a 248 nm (KrF) beam at several fluence values. Surface morphologies of the films dependent strongly on laser fluence and deposition rate of the reactant. In the optimized conditions, mesh-like structures consisting of numerous fibers were observed. Electric conductivity of the film prepared by UV-LAD at 10 mJ cm−2 pulse−1 increased from less than 10−7 S cm−1 up to 10−3 S cm−1 on iodine doping. FT-IR, photoelectron spectroscopy (XPS) and ultra violet—visible (UV—vis) spectroscopy measurements show that, although sulfur atoms are eliminated to some extent, polymerization occurs basically at 2 and 5 positions of 2,5-DCT by effective elimination of halogen atoms to form polythiophene with various π-conjugation lengths. The film contained both soluble and insoluble components in tetrahydrofuran (THF) and acetonitrile (AN) solvents. Components with π-conjugation length corresponding to those of an oligothiophene with 3 ± 1 thiophene units are dominant for soluble components. Optical band gap is estimated to be 2.93 eV for insoluble components in the film.

Density functional calculations have been made on a binuclear metal carbonyl ion Cr2(CO)6+ found in our laser ablation–molecular beam (LAMB) experiment. Optimized structures are calculated for three different conformations: T33 of D3d symmetry with three terminal carbonyl groups on each chromium atom, B2T22 of D2h symmetry with two bridging carbonyl groups and two terminal carbonyl groups on each chromium atom, and B4T11 of D4h symmetry with four bridging carbonyl groups and one terminal carbonyl group on each chromium atom. The most stable conformation is T33 which is 36.76 and 286.44 kJ mol−1 lower in energy than B2T22 and B4T11, respectively. The difference of conformation exerts a significant influence on the internuclear distance between chromium and the carbon of terminal CO, but hardly on the Cr–Cr bond length. For B2T22 and B4T11, longer C–O distances for bridging carbonyls compared with those for terminal ones indicate effective π*-back donation from the chromium atom to the bridging carbonyl groups. Furthermore, the relative abundance of Cr2(CO)n+ (n = 0–6) observed in our previous experimental study can be explained qualitatively by comparison of the excess energy produced in the formation of a Cr+–Cr bond with the CO dissociation energy of Cr2(CO)6+. © 1998 John Wiley & Sons, Ltd.

Amorphous semiconducting organic thin films are prepared on temperature-controlled substrates by excimer laser ablation (ELA) of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with 308 nm (XeCl) beams. Drastic increase in electric conductivity and decrease in the FT-IR peak intensities related to the side groups of PTCDA monomers are observed for films prepared on substrates above 200°C. Electric conductivity of a film prepared on a substrate at 300°C comes up to 10−1 S cm−1. Raman spectroscopic measurement reveals that this film partially contains polyperinaphthalene (PPN) structure. Structural change by increasing substrate temperature and film formation process are discussed.

Ammonia–water mixed-ligand complexes of monopositive metal ions M+ (M=Mg, Al, Mn, and Co) were prepared in the gas phase by reactions of metal ions laser-ablated from a metal substrate in vacuum with ammonia–water binary clusters in a molecular beam injected nearby [the laser-ablation–molecular beam (LAMB) method]. Relative abundances of M+(NH3)m(H2O)n are characterized by intensity gaps which indicate limited (typically 2 or 3) coordination (solvation) numbers in the first coordination (solvation) sphere. Three patterns of competitive coordination (solvation), i.e., selective, nonselective, and magic-number-like, are observed. The patterns are metal-specific and relatively independent of stagnation ratios of two component gases. The coordination numbers as judged from the intensity gaps remain the same throughout the stagnation ratios studied. A model simulation of the dynamic processes involved was made under simple-minded assumptions: (1) the ensemble of metal complex ions starting from the reaction re...

In the laser ablation–molecular beam (LAMB) method, laser ablation of metal substrates in vacuum is utilized for the formation of novel organometallic and metal complex compounds containing monopositive metal ions. Mixed-metal binuclear carbonyl ions [MCr(CO)n]+, n=0–6, are prepared in the gas phase by the reaction of laser-ablated metal ions (M+) and Cr(CO)6 in the molecular beam injected nearby. The relative abundance of these ions, for M=transition metals, can essentially be explained by the M+–Cr bond dissociation energies. Results of density functional calculation show that this is essentially valid. © 1997 John Wiley & Sons, Ltd.