Impacts of KF Post-Deposition Treatment on the Band Alignment of Epitaxial Cu(In,Ga)Se2 Heterojunctions

In this study, we investigated band alignments at CdS/epitaxial CuIn_xGa_1-xSe₂ (epi-CIGSe) and epi-CIGSe/GaAs heterointerfaces for solar cell applications using ultraviolet, inverse, and X-ray photoemission spectroscopy (UPS, IPES, and XPS) techniques. We clarified the impacts of KF postdeposition treatment (KF-PDT) at the CdS/epi-CIGSe front heterointerfaces. We found that KF-PDT changed the conduction band alignment at the CdS/epi-CIGSe heterointerface from a cliff to flat configuration, attributed to an increase in the electron affinity (E_A) and ionization potential (I_P) of the epi-CIGSe surface because of a decrease in Cu and Ga contents. Herein, we discuss the correlation between the impacts of KF-PDT and the solar cell performance. Furthermore, we also investigated the band alignment at the epi-CIGSe/GaAs rear heterointerface. Electron barriers were formed at the epi-CIGSe/GaAs interface, suppressing carrier recombination as the back surface field. Contrarily, a hole accumulation layer is formed by the valence band bending, which is like Ohmic contact.

Optical and Structural Properties of High-Efficiency Epitaxial Cu(In,Ga)Se2 Grown on GaAs

Photovoltaic devices based on Cu(In,Ga)Se₂ (CIGS) typically employ polycrystalline thin films as the absorber layer. This is because, to date, the highest conversion efficiencies have been attained with polycrystalline CIGS films. Recently, Nishinaga et al. presented an epitaxial CIGS thin-film solar cell grown on a GaAs (100) substrate with a conversion efficiency of 20.0%. In this contribution, we study the optical and structural properties of this high-efficiency epitaxial film, along with others with different compositions using cathodoluminescence spectrum imaging and transmission electron microscopy. A comparison of the high-efficiency epitaxial film and a traditional polycrystalline film with a similar global composition reveals significant differences in microstructure and uniformity of emission properties despite similar performance. The analysis of epitaxial films with a higher gallium concentration indicates that the emission characteristics and nature of extended defects in epitaxial CIGS films are strongly dependent on the gallium content. The results presented here provide evidence that, with further optimization, photovoltaic conversion efficiencies of epitaxial CIGS films could exceed those of polycrystalline CIGS.

Improving the Open Circuit Voltage through Surface Oxygen Plasma Treatment and 11.7% Efficient Cu2ZnSnSe4 Solar Cell

The photovoltaic performance of Cu₂ZnSnSe₄ (CZTSe) solar cells subjected to surface oxygen plasma treatments is investigated. The observed improvements are related to an enhancement of the open circuit voltage V_OC, that is, the suppression of the V_OC deficit. The V_OC monotonically increases with treatment time up to 0.460 V. The origin of this improvement is discussed, and it is concluded that the effectiveness of the surface treatment is not due to oxygen-related alloying but instead to the homogeneous oxidation and removal of the oxidized CZTSe surface layer. The surface oxygen content increases with surface treatment time, although surface oxides are fully removed after ammonia treatment, which is conducted in a similar manner to CdS buffer deposition. The reduction of surface recombination is confirmed by time-resolved photoluminescence measurements, and the minority carrier lifetime deduced using the fast decay component increases with increasing treatment time. The relationship between photovoltaic properties and lifetime is clearly demonstrated. The best-performing CZTSe solar cell obtained using surface oxygen treatment demonstrates a conversion efficiency of 11.7%, which is higher than those of previous reports on CZTSe cells.

Band Alignment of the CdS/Cu2Zn(Sn1- xGe x)Se4 Heterointerface and Electronic Properties at the Cu2Zn(Sn1- xGe x)Se4 Surface: x = 0, 0.2, and 0.4

The surface electronic properties of the light absorber and band alignment at the p/n heterointerface are key issues for high-performance heterojunction solar cells. We investigated the band alignment of the heterointerface between cadmium sulfide (CdS) and Ge-incorporated Cu₂ZnSnSe₄ (CZTGSe), with Ge/(Ge + Sn) ratios ( x) between 0 and 0.4, by X-ray photoelectron, ultraviolet, and inversed photoemission spectroscopies (XPS, UPS, and IPES, respectively). In particular, we used interface-induced band bending in order to determine the conduction band offset (CBO) and valence-band offset (VBO), which were calculated from the core-level shifts of each element in both the CdS overlayer and the CZTGSe bottom layer. Moreover, the surface electronic properties of CZTGSe were also investigated by laser-irradiated XPS. The CBO at the CdS/CZTGSe heterointerface decreased linearly, from +0.36 to +0.20 eV, as x was increased from 0 to 0.4; in contrast, the VBO at the CdS/CZTGSe heterointerface was independent of Ge content. Both UPS and IPES revealed that the Fermi level at the CZTGSe surface is located near the center of the band gap. The hole concentration at the CZTGSe surface was on the order of 10¹¹ cm^-3, which is much smaller than that of the bulk (∼10¹⁶ cm^-3). We discuss the differences in hole deficiencies near the surface and in the bulk on the basis of laser-irradiated XPS and conclude that hole deficiencies are due to defects distributed near the surface with densities that are lower than in the bulk, and the Fermi level is not pinned at the CZTGSe surface.

Cu(In,Ga)Se2 Solar Cells with Amorphous In2O3-Based Front Contact Layers

Amorphous (a-) In₂O₃-based front contact layers composed of transparent conducting oxide (TCO) and transparent oxide semiconductor (TOS) layers were proved to be effective in enhancing the short-circuit current density (J_sc) of Cu(In,Ga)Se₂ (CIGS) solar cells with a glass/Mo/CIGS/CdS/TOS/TCO structure, while maintaining high fill factor (FF) and open-circuit voltage (V_oc). An n-type a-In-Ga-Zn-O layer was introduced between the CdS and TCO layers. Unlike unintentionally doped ZnO broadly used as TOS layers in CIGS solar cells, the grain-boundary(GB)-free amorphous structure of the a-In-Ga-Zn-O layers allowed high electron mobility with superior control over the carrier density (N). High FF and V_oc values were achieved in solar cells containing a-In-Ga-Zn-O layers with N values broadly ranging from 2 × 10¹⁵ to 3 × 10¹⁸ cm^-3. The decrease in FF and V_oc produced by the electronic inhomogeneity of solar cells was mitigated by controlling the series resistance within the TOS layer of CIGS solar cells. In addition, a-In₂O₃:H and a-In-Zn-O layers exhibited higher electron mobilities than the ZnO:Al layers conventionally used as TCO layers in CIGS solar cells. The In₂O₃-based layers exhibited lower free carrier absorption while maintaining similar sheet resistance than ZnO:Al. The TCO and TOS materials and their combinations did not significantly change the V_oc of the CIGS solar cells and the mini-modules.

Interfacial alkali diffusion control in chalcopyrite thin-film solar cells

Alkali elements, specifically sodium (Na), are key materials to enhance the energy conversion efficiencies of chalcopyrite and related thin-film photovoltaic solar cells. Recently, the effect of potassium (K) has also attracted attention because elemental K has unique effects different from Na as well as a similar beneficial effect in improving device performance. In this study, the control of selective alkali K and Na diffusion into chalcopyrite thin-films from soda-lime glass substrates, which serve as the monolithic alkali source material and contain both K and Na, is demonstrated using ternary CuGaSe2. Elemental K is found to be incorporated in the several ten nanometer thick Cu-deficient region, which is formed on the CuGaSe2 film surface, while Na is ejected, although both K and Na diffuse from the substrate to the CuGaSe2 film surface during growth. The alkali [K]/[Na] concentration ratio in the surface region of CuGaSe2 films strongly depends on the film structure and can be controlled by growth parameters under the same substrate temperature conditions. The results we present here offer new concepts necessary to explore and develop emerging new chalcopyrite and related materials and optimize their applications.

Observation of Sodium Diffusion in CIGS Solar Cells with Mo/TCO/Mo Hybrid Back Contacts

CIGS solar cells were fabricated on a hybrid back contact comprised of a TCO layer (ZnO:Ga (GZO)) and Mo layers. It was discovered that an additional Mo layer introduced underneath the TCO layer promotes sodium diffusion through the TCO back contact into the upper CIGS absorber layer. Improvement in VOC and JSC values relative to those of sodium-free solar cells was achieved with the Mo/GZO/Mo hybrid back contact as a result of the enhanced sodium diffusion.

Ohmic Contact Behavior of Pt/Ni/Au to p-ZnO

The electrical properties of single Pt (30 nm) and Pt (30 nm)/Ni (30nm)/Au(50nm) multilayer contacts on moderately doped p-ZnO (Na = 5.0 × 1017 /−3) were investigated. Although linear current-voltage characteristics were observed for all samples, a sample that was annealed for 1 min at a temperature above 500 °C resulted in an ohmic contact with good characteristics. The best ohmic contact to p-type ZnO was obtained using a Pt/Ni/Au multilayer contact that was annealed at 600 °C for 1 min under a N2 ambient, showing a specific contact resistance Rc of 1.97 × 10−5 Ω cm2. The fundamental mechanisms for the lower contact resistivity of Pt/Ni/Au contacts are discussed based on glancing angle x-ray diffraction results and Auger depth profile analysis of the multilayer alloying process. Furthermore, we fabricated a ZnO p-n homojunction using Pt/Ni/Au and Ti/Au as the p-type and n-type ohmic contact metal, respectively. The threshold voltage was determined to be about 3.7 V, comparable to the bandgap energy of ZnO.

Study of Band Alignment at CBD-CdS/Cu(In1-xGax)Se2 (x = 0.2 - 1.0) Interfaces by Photoemission and Inverse Photoemission Spectroscopy

Dependence of band alignments at interfaces between CdS by chemical bath deposition and Cu(In1-xGax)Se2 by conventional 3-stage co-evaporation on Ga substitution ratio x from 0.2 to 1.0 has been systematically studied by means of photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). For the specimens of the In-rich CIGS, conduction band minimum (CBM) by CIGS was lower than that of CdS. Conduction band offset of them was positive about +0.3 ~ +0.4 eV. Almost flat conduction band alignment was realized at x = 0.4 ~ 0.5. On the other hand, at the interfaces over the Ga-rich CIGS, CBM of CIGS was higher than that of CdS, and CBO became negative. The present study reveals that the decrease of CBO with a rise of x presents over the wide rage of x, which results in the sign change of CBO around 0.4 ~ 0.45. In the Ga-rich interfaces, the minimum of band gap energy, which corresponded to energy spacing between CBM of CdS and valence band maximum of CIGS, was almost identical against the change of band gap energy of CIGS. Additionally, local accumulation of oxygen related impurities was observed at the Ga-rich samples, which might cause the local rise of band edges in central region of the interface.

Bandgap Engineering of ZnO Transparent Conducting Films

Low resistivity and transparent Al doped ZnMgO films were deposited on glass substrates by a pulsed laser deposition system. For up to 32 atm% of Mg content, segregation of a MgO phase was not observed. The bandgap of these films could be widened to about 4 eV with increasing Mg content. The relation between bandgap and resistivity was found to be a trade-off; i.e. the larger the bandgap, the higher the resistivity. The maximum bandgap among films with an electrical resistivity of less than 10-3 Ω cm was 3.94 eV. The average optical transmittance of these films was more than 90 % for wavelengths λ between 400 and 1100 nm. The transmittance around λ = 330 nm was still 50 %.

High-Quality Transparent Conducting Oxide Films Deposited by a Novel Ion Plating Technique

A novel ion plating technique that has the attributes of both superb controllability of the high density plasma used as well as ion beam shape has been developed and applied to the deposition of transparent conducting oxides. The advantages of this technique include reduced ion damage, scale-up capability, in-plane uniformity, the use of low growth temperatures and fast deposition rates suggesting that the technique is very promising for a variety of applications such as solar cells and organic device fabrication. Gallium doped zinc oxide films have been deposited on glass substrates at 200°C. Resistivities as low as ρ∼2.7×10-4 Ω-cm with high transparency have been demonstrated. In addition, this technique has been successfully applied to large area deposition such as 65 cm × 55 cm-sized glass substrates.

Formation of ionic bonds between a fatty-acid Langmuir-Blodgett monolayer and a zinc oxide substrate

A fatty-acid Langmuir-Blodgett (LB) monolayer ionically adsorbed to the substrate has been prepared by adopting ZnO-based conductor and pure water respectively as the substrate and subphase. Ionization of the fatty-acid molecules has been detected by infrared reflection-absorption spectroscopy (IR-RAS), which is enabled by the condensed free electrons in the doped ZnO substrate. On the contrary, IR-RAS measurements have indicated that fatty-acid molecules transferred onto Au and indium-tin-oxide substrates from a pure-water surface are not ionized. In addition, it has been demonstrated that these ionically bonded fatty-acid monolayers protect the ZnO transparent electrode from chemical attack by NH(3) gas. Since the LB technique is a simple method applicable to a wide variety of materials, the present results may lead to a new way of obtaining functional organic-inorganic nanosystems.

Microstructural evolution of ZnO by wet-etching using acidic solutions

The characteristics of the wet-etching of ZnO thin films were investigated using hydrochloric and phosphoric acid solutions as etchants. The etch rate of ZnO films, using a highly diluted hydrochloric acid solutions at a concentration of 0.25% in deionized water, was determined to be about 120 nm/min, and linearly increased with increasing the acid concentration. The surface of ZnO(0001) etched by an HCl solution, observed by scanning electron microscopy, showed a rough morphology with a high density of hexagonal pyramids or cones with sidewall angles of about approximately 45 degrees. Moreover, the sidewall angles of the masked area were similar to those of the pyramids on the surface. In comparison, the surface of ZnO(0001) etched by a phosphoric acid had a smooth surface morphology. The origin of this difference is from the very initial stage of etching, indicating that the etch-mechanism is different for each solution. Furthermore, when H3PO4 was added to the HCl aqueous solution, the morphology of the etched surface was greatly enhanced and the sidewall angle was also increased to about 65 degrees.

Direct observation of nitrogen location in molecular beam epitaxy grown nitrogen-doped ZnO

ZnO is a wide band gap, naturally n-type semiconductor with great promise for optoelectronic applications; the main obstacle yet to be overcome is p-type doping. Nitrogen, the most promising candidate currently being pursued as a dopant, has been predicted to preferentially incorporate into the ZnO lattice in the form of a N-2 molecule at an O site when a plasma source is used, leading to compensation rather than p-type doping. We demonstrate this to be incorrect by using N K-edge x-ray absorption spectra and comparing them with first-principles calculations showing that nitrogen, in fact, incorporates substitutionally at O sites where it is expected to act as an acceptor. We also detect the formation of molecular nitrogen upon annealing. These results suggest that effective p-type doping of ZnO with N may be possible only for low-temperature growth processes.

Wegener's granulomatosis with onset of acute pancreatitis and rapid progress. A case report

Although Wegener's granulomatosis is a rare disorder, the clinical and histological characteristics are well known. However, Wegener's granulomatosis with the onset of acute pancreatitis has rarely been reported. We discuss the case of Wegener's granulomatosis in a 65-year-old man, presenting with acute pancreatitis and whose disease progressed rapidly.

[Study of transforming growth factor-alpha expression in duodenal ulcer]

Various growth factors were also reported to promote healing of peptic ulcer. We have used a monoclonal antibody in conjunction with a standard immunohistochemical technique to characterize the expression of transforming growth factor-alpha (TGF-alpha) in duodenal ulcer. TGF-alpha immunoreactivity is found in Brunner's gland, also in immature gland and in duodenal epitheliums, but not in gastric metaplasia of the duodenum. TGF-alpha expression of healing and scar stage was higher than that of active stage. The presence or absence of Helicobacter pylori infection did not affect the expression of TGF-alpha in duodenal ulcer.

Second-harmonic generation from chalcopyrite-structure semiconductor thin films

We propose that thin films of tetragonal chalcopyrite-structure semiconductor media are promising nonlinearoptical (NLO) materials for the following reasons: Phase matching is possible with them in principle, they can be utilized in a waveguide geometry, and they are compatible with III-V substrates. We investigate the second-order NLO properties of chalcopyrite-structure CuInSe(2) and CuGaSe(2) thin films grown on GaAs(001), using optical second-harmonic (SH) generation at a fundamental wavelength of 790 nm. The SH intensities produced by approximately stoichiometric CuInSe(2) and CuGaSe(2) thin films are similar to that of GaAs. The second-order optical nonlinearities are strongly curtailed in nonstoichiometric thin films.

Effects of nitric oxide synthase inhibitors on duodenal alkaline secretion in anesthetized rats

We examined the effects of NG-nitro-L-arginine methyl ester (L-NAME), the nitric oxide (NO) synthase inhibitor, on duodenal HCO3- secretion in anesthetized rats. L-NAME (1-5 mg/kg i.v.), given as a single injection, increased HCO3- secretion in a dose-dependent manner. This effect of L-NAME was mimicked by NG-monomethyl-L-arginine (50 mg/kg i.v.) and was significantly antagonized by the simultaneous administration of L-arginine (200 mg/kg i.v.) but not D-arginine. The increased HCO3- response to L-NAME was also significantly reduced in vagotomized animals. These findings suggest that the inhibition of NO biosynthesis leads to an increase of duodenal HCO3- secretion, partly mediated by the vagus nerves.

HTLV-I infection in patients with autoimmune thyroiditis (Hashimoto's thyroiditis)

To investigate the possible relationship of HTLV-I virus infection to autoimmune thyroid disease, we examined, firstly, the frequency of HTLV-I seropositivity among patients with Hashimoto's thyroiditis and, secondly, the frequency of Hashimoto's thyroiditis in patients with HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP). Of 144 patients with Hashimoto's thyroiditis in the Tokushima and Kochi Prefectures, Japan, 9 (6.3%) were positive for serum HTLV-I virus antibody 2 of whom were confirmed histologically to have Hashimoto's thyroiditis. This percentage is significantly higher (P < 0.01) than the estimated prevalence (2.2%) of HTLV-I carriers among the general population in this region. Of 9 patients with HAM/TSP, 3 (33.3%), including 2 biopsy-proven cases, had evidence of Hashimoto's thyroiditis. This proportion is apparently much higher than the prevalence (1.7%) of Hashimoto's thyroiditis in the general population. These findings suggest that HTLV-I virus may be related to the development of Hashimoto's thyroiditis.

[Calcium-dependent signaling of acid secretion in isolated parietal cells from guinea pigs and its modification by ethanol]

Treatment of isolated parietal cells from guinea pig gastric mucosa with ethanol caused a rapid increase in [Ca2+]i and concomitant decrease in the capacity for carbachol-stimulated acid secretion in a dose dependent manner. Carbachol rapidly increased the [Ca2+]i from trimethoxybenzoic acid 8-(diethylamino)-octyl ester sensitive intracellular pool. In contrast, the increase with ethanol was through La3+ sensitive Ca2+ channel from external source, which suppressed the Ca2+ response subsequently stimulated with carbachol. Pretreatment of the cells with EGTA or La3+ completely prevented the elevation of [Ca2+]i with ethanol and preserved the Ca2+ response to carbachol. These findings indicate that ethanol-induced elevation of [Ca2+]i may desensitize the stimulation of carbachol. Furthermore, treatment of the parietal cells with ethanol increased the activity of protein kinase C in both cytosolic and membrane fractions of the cells. Activation of protein kinase C with phorbol diester suppressed the capacity for acid secretion. These results suggest that ethanol may inhibit the carbachol-stimulated acid secretion through the desensitization of Ca2+ response and the activation of protein kinase C.

[Effects of ethanol on acid secretion by isolated parietal cells from guinea pig]

We studied the effects of ethanol (0.1-10%) on acid secretion of parietal cell-rich fractions isolated from guinea pig gastric mucosa. Ethanol (0.1-3%) increased histamine-stimulated cAMP content, while over 1% ethanol decreased histamine-stimulated acid secretion. H+, K(+)-ATPase activity in microsomal fraction also decreased after treatment with 3% ethanol. Thus, ethanol may disturb the signalling process from cAMP to H+, K(+)-ATPase. On the other hand, carbachol-stimulated acid secretion was more sensitive to ethanol than that with histamine, and 0.1% ethanol suppressed the acid secretion. This effect was well correlated with the extent of the ethanol-induced increase of [Ca2+]i and with the attenuation of [Ca2+]i response following carbachol stimulation. The calcium response may be a primary target against ethanol in carbachol-dependent process. In conclusion, low-dose ethanol have multi-effects on these critical intermediary steps in acid secretion.

[A case of intrapulmonary lymph node simulating small carcinoma of the lung]

A 48-year-old male was admitted for further examination of a coin lesion with a diameter of 8 mm seen on chest X-ray. The patient was a heavy smoker and his serum level of CEA was elevated to 29.8 ng/ml. Since the broncho-fiberscopic examination was not able to yield a definitive diagnosis, an operation was performed as lung cancer was suspected. According to the histological examination, the small nodule was diagnosed as an intrapulmonary lymph node with anthracosis and silicotic nodules. A review of the limited number of case reports shows that men are more prone to intrapulmonary lymph nodes, and that the patients were all smokers but not necessarily with occupational experience of exposure to silica.

[Study on cefotaxime in respiratory surgery: transfer to lung tissue and kinetics in serum]

Cefotaxime (CTX) was intravenously administered in a dose of 1 g to patients just prior to lung surgery. Lung tissue specimens were collected at 1, 2 and 3 hours after the CTX administration, and the concentration of CTX in each specimen was determined. At the same time, the concentration of CTX in the serum was also measured. The results are summarized below. 1. Determination of the CTX concentration in the lung tissue using bioassay showed values of 3.78 +/- 1.93 micrograms/g at 1 hour after CTX administration, 1.91 +/- 0.92 microgram/g at 2 hours, and 1.19 +/- 1.04 micrograms/g at 3 hours. 2. Determination of the CTX concentration in the serum using bioassay showed values of 36.9 +/- 14.4 micrograms/ml at 30 minutes after CTX administration, 22.5 +/- 10.5 micrograms/ml at 1 hour, 12.8 +/- 6.32 micrograms/ml at 2 hours, 8.52 +/- 5.54 micrograms/ml at 3 hours, and 3.98 +/- 3.19 micrograms/ml at 6 hours. The serum half-life was calculated to be 1.82 hours. 3. The CTX concentration of 3.78 +/- 1.93 micrograms/g in the lung tissue at 1 hour after CTX administration was more than 10 times higher than the MIC80 values for Streptococcus pneumoniae (MIC80 less than or equal to 0.025 microgram/ml) and Klebsiella pneumoniae (0.05 micrograms/ml), 2 of the principal causative organisms of respiratory tract infections. The pattern of change in concentrations of CTX in the serum of these surgical patients was concluded to be similar to the pattern in healthy adult subjects. On the basis of the results summarized above, it appears that CTX is a useful antimicrobial agent for application in the field of respiratory surgery.

X-linked dominant control of F-cells in normal adult life: characterization of the Swiss type as hereditary persistence of fetal hemoglobin regulated dominantly by gene(s) on X chromosome

Fetal hemoglobin (HbF) levels determined in healthy Japanese adults ranged from 0.3% to 16.0% as F cells and 0.17% to 2.28% as HbF content, which were the same as those obtained in other countries. The frequency distribution of 300 healthy adults with various numbers of F cells consisted statistically of two different groups, low and high F-cell groups. Individuals with greater than or equal to 4.4% of F cells (HbF about 0.7%) were defined as the high F-cell trait, which accounted for 11.3% of males and 20.7% of females. Family studies of 21 probands with this trait and sex-different frequency analyses in the population and probands revealed X-linked dominant inheritance. Two other families of the trait associated with color blindness were described, although no definitive evidence for linkage was obtained between the two. A review of population and family studies reported in the literature indicated that persons with Swiss-type hereditary persistence of fetal hemoglobin (HPFH) are of the same kind as this trait in their incidence and inheritance form, but represent a portion of the trait with higher levels of HbF or F cells. The existence of X chromosome-localized regulatory gene(s) for the developmental switch of human Hb production is discussed.

Effects of S-596, a new beta-adrenoceptor blocking agent on the left ventricular performance of normal subjects during exercise

The effects of d1-2-(3'-t-butylamino-2'-hydroxypropylthio)-4-(5'-carbamoyl-2'-thi enyl) thiazole hydrochloride (S-596) were evaluated in 9 normal volunteers. Exercise echocardiography was performed in the semi-supine position before and 2, 4 and 24 hours after the oral administration of 15 mg of S-596. Two hours after administration, resting heart rate was unchanged, compared with control, but systolic blood pressure at rest was slightly decreased (114 +/- 6 vs 106 +/- 10 mmHg, p less than 0.05). Left ventricular dimensions were unchanged, but shortening fraction was increased in the resting state (30.3 +/- 4.6 vs 33.1 +/- 4.8%, p less than 0.05). During exercise on oral S-596, heart rate and systolic blood pressure responses were reduced (127 +/- 11 in control vs 108 +/- 6 beats/min on S-596, 198 +/- 25 vs 168 +/- 23 mmHg, p less than 0.001 and 0.05, respectively). Left ventricular end-diastolic dimension was not significantly altered by S-596 compared with the preceding control exercise test; however, end-systolic dimension was significantly larger after beta blockade with S-596 (2.6 +/- 0.4 vs 3.0 +/- 0.4 cm, p less than 0.05). Shortening fraction and cardiac output decreased significantly (43.7 +/- 3.7 vs 40.0 +/- 5.7%, 9.5 +/- 1.4 vs 8.4 +/- 1.3 L/min, p less than 0.05 and 0.01, respectively). These effects of S-596 were maximal at 2 hours after oral administration with reduced response of heart rate to exercise lasting for 24 hours. Compared with the effects of propranolol (30 mg, given orally) in the same subjects, beta-adrenergic blockade during exercise with S-596 was equivalent to or greater than that of propranolol. Thus, S-596 has little, if any, effect on resting left ventricular performance, but demonstrates potent negative chronotropic and inotropic effects during exercise in normal human subjects. Its beta-adrenergic blocking action also has long acting properties, especially its chronotropic effect.

Simultaneous changes of left ventricular and left atrial size and function in normal subjects during exercise

We performed dual M-mode exercise echocardiography, which records left ventricular (LV) and left atrial (LA) echocardiograms simultaneously, in 10 normal subjects to investigate mechanisms of cardiac adaptation to dynamic exercise. The LV end-diastolic dimension (EDD) increased significantly as exercise increased from mild to moderate (3-5%, p less than 0.05 and 0.001). At peak exercise the EDD was slightly increased, but it returned to the baseline during recovery. The LV end-systolic dimension (ESD) showed a progressive decrease with the severity of exercise (5-13%, p less than 0.05 and 0.001). It decreased further immediately after exercise (17-20%) and then returned to the resting value. The LV stroke dimension and fractional shortening increased as exercise changed from mild to moderate and reached a plateau at peak exercise. During recovery, they showed a transient increase and then decreased. By contrast, the LA dimensions, both maximum and minimum, increased significantly as exercise changed from mild to moderate (15-16% and 16-19%, p less than 0.01 and 0.001, respectively), but they were lower at peak exercise (12 and 14%). They returned rapidly to the resting values immediately after exercise. Thus, during exercise, LV function is augmented by the Frank-Starling mechanism in combination with increased contractility, while the LA is enlarged to receive the increased venous return accompanying dynamic exercise. These exercise-induced changes in LV performance return gradually to the resting state, but LA size recovers rapidly after the cessation of exercise.

Left ventricular size and performance during graded supine exercise in normal subjects

To investigate left ventricular size and performance during graded submaximal exercise, 14 normal subjects with a mean age of 21 years exercised in a supine position to achieve the target heart rate. Using two-dimensional echocardiography, we recorded and analysed the left ventricular (LV) cross-sectional area and internal dimension at the level of the tips of the mitral valve at rest and during mild, moderate and severe exercise. The heart rate and systolic blood pressure increased substantially from rest to peak exercise (71 +/- 11 to 162 +/- 10 beats/min, 122 +/- 10 to 204 +/- 22 mmHg). The end-diastolic cross-sectional area and internal dimension (EDA & EDD) increased by 1.1-2.2 cm2 (7-13%) and 0.2-0.3 cm (4-7%), respectively, from mild to moderate exercise, (p less than 0.05-0.001). At peak exercise, however, these decreased and showed no statistically significant difference from the values at rest. The end-systolic cross-sectional area and internal dimension (ESA & ESD) decreased by 1.1 to 1.6 cm2 (14-20%) and 0.2-0.3 cm (7-10%), respectively, from moderate to severe exercise (p less than 0.01-0.001). However, the end-systolic values during mild exercise were not significantly different from those at rest. The stroke area (EDA-ESA) and dimension (EDD-ESD) increased by 1.6-2.6 cm2 (19-31%) and 0.2-0.6 cm (25-38%), respectively, during all levels of graded exercise (p less than 0.05-0.001). The percent change of LV cross-sectional area and internal dimension during systole increased gradually from rest to moderate exercise (51.0 +/- 7.1 to 61.9 +/- 4.4%, 35.4 +/- 3.9 to 45.0 +/- 3.7%), respectively, and showed no further increase during peak exercise. The mean circumferential fiber shortening velocity increased sharply from rest to peak exercise (1.27 +/- 0.14 to 2.25 +/- 0.21 circ/sec). These results suggest that the Frank-Starling mechanism operates during mild to moderate exercise, and contractility increases markedly at moderate to severe exercise levels as cardiac performance is augmented during graded submaximal exercise.

[Analysis of coronary hemodynamics in exercise by T1-201 scintigraphy: examination of rates of change of cardiac output, myocardial blood flow distribution, coronary blood flow and coronary vascular resistance]

From our observation that initial distribution of 201T1 in tissue is mainly dependent on blood flow distribution, we designed the method to obtain the rates of change of coronary blood flow and coronary vascular resistance and applied it to the analysis of coronary hemodynamics in patients with ischemic heart disease during submaximal exercise. We measured the rates of change of cardiac output (delta CO) and myocardial blood flow distribution (delta Fract ) in two occasions by the sequential two injections of T1, and obtained the rate of change of coronary blood flow (delta Flow) from delta CO and delta Fract . Using the rate of change of mean blood pressure, we calculated also the rate of change of coronary vascular resistance (delta CVR). The initial components of histograms of the right ventricle by the first and second injections of T1 were fitted into gamma function curve. S1 and S2 were the areas bounded by the curve and baseline of the first and second injections, and then the cardiac output ratio was estimated by R X S1/S2, where R was the dose ratio measured by another camera system. The five min count rates on the myocardium by the first (H1) and second (H2) injections of T1 were calculated five min after the injection. H2 was approximately H1 X R in the same condition of T1 injection but H2 was not equal to H1 X R, when the T1 injection was done in the different loading condition. Therefore the rate of change of myocardial blood flow distribution was calculated as delta Fract = (H1 X R-H2)/H2.(ABSTRACT TRUNCATED AT 250 WORDS)

The group mean SEP of normal human subjects

The following conclusions were deduced from the SEPs of 100 normal human subjects, whose mean age was 21.80+/-1.62. It was confirmed that the waveform of a Group Mean SEP and of a Group SD each converges to a waveform different from a flat horizontal line. The waveform of the Group Mean SEP consisted of 12 components, and was roughly tetraphasic within 500 msec in latency. Large discrepancies were found in the later components between the Group Mean SEP and the Group Schematic SEPs reported by others, although some coincidences were shown in the early components within 100 msec in latency. The results derived from the Scaled SEPs, which were converted from the (unscaled) SEPs, indicated the possibility of a reduction of the data by the Amplitude Scaling.