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Vibrational spectra often require baseline removal before further data analysis can be performed. Manual (i.e., user) baseline determination and removal is a common technique used to perform this operation. Currently, little data exists that details the accuracy and precision that can be expected with manual baseline removal techniques. This study addresses this current lack of data. One hundred spectra of varying signal-to-noise ratio (SNR), signal-to-baseline ratio (SBR), baseline slope, and spectral congestion were constructed and baselines were subtracted by 16 volunteers who were categorized as being either experienced or inexperienced in baseline determination. In total, 285 baseline determinations were performed. The general level of accuracy and precision that can be expected for manually determined baselines from spectra of varying SNR, SBR, baseline slope, and spectral congestion is established. Furthermore, the effects of user experience on the accuracy and precision of baseline determination is estimated. The interactions between the above factors in affecting the accuracy and precision of baseline determination is highlighted. Where possible, the functional relationships between accuracy, precision, and the given spectral characteristic are detailed. The results provide users of manual baseline determination useful guidelines in establishing limits of accuracy and precision when performing manual baseline determination, as well as highlighting conditions that confound the accuracy and precision of manual baseline determination.

To study the effects of egg phosphatidylcholine (EPC) and hydrogenated egg phosphatidylcholine (HEPC) on the leakage of doxorubicin liposome in vitro and the resident time in blood.By the means of dialysis, the leakage of EPC (EPC-NL) and HEPC normal liposomes (HEPC-NL) in fetal cattle serum (FCS) was determined at 37 degrees C and in phosphate buffer solution (PBS) at 37 degrees C, 20 degrees C and 4 degrees C. Furthermore, the pharmacokinetics of EPC and HEPC sterically stabilized liposomes (EPC-SSL and HEPC-SSL) were studied by HPLC.The leakage of doxorubicin from HEPC-NL is slower than that of EPC-NL in FCS at 37 degrees C. But in PBS at all of three different temperatures, the results are completely reversed, i.e., the leakage of EPC-NL is slower than that of HEPC-NL. Further studies on pharmacokinetics showed that the mean residence time of HEPC-SSL in blood is 23.3 h, while that of EPC-SSL is 12.0 h, and the area under the curve (AUC) of concentration of HEPC-SSL is larger than that of EPC-SSL.HEPC-SSL is a better carrier in delivering the drugs to the extravascular sites than EPC-SSL.

Discusses the specification and automated synthesis of mixed synchronous/asynchronous systems in the context of a VHDL-based design environment. We propose a flexible paradigm for describing asynchronous behavior in VHDL that supports (1) the description of behavior as a signal transition graph (STG), (2) its expression in the form of an initializable edge-triggered finite state machine, and (3) the specification of a level-sensitive asynchronous finite state machine. An important feature is that free-running signals such as clocks can be included in the asynchronous specifications. The input specification, consisting of timing diagrams and/or the behavior and interface specifications for a set of interacting processes, is mapped into an appropriate combination of hazard-free asynchronous circuits and synchronous circuits. >

Summary form only given. Highly miniaturized electron beam columns based on a field emission source and microfabricated electron optical components have been developed. A 1 keV microcolumn operating with a miniaturized Zr/O/W Schottky emitter has been successfully evaluated for the first time. This paper will present the results obtained with the new microcolumn and discuss present efforts to further improve column performance with respect to resolution, beam current, and deflection field size.

To determine the hepatitis C virus (HCV) genotype distribution in Taiwan and to clarify the relationship between genotype and the pathogenesis of HCV infection, 1,164 subjects positive for serum HCV antibodies and HCV RNA from three HCV hyperendemic areas (Masago, Tzukuan, and Taoyuan) and a tertiary referral center in Taiwan were studied during 1995-1997. HCV genotypes and viral loads were determined using Okamoto's method and branched DNA assay, respectively. Genotype 1b was the most prevalent in Tzukuan (61.9%), Taoyuan (76.9%), and the referral center (47.0%). By contrast, genotype 2a was the major HCV type in Masago (63.5%). Prevalence of genotype 1b positively and that of genotype 2a negatively correlated to age, regardless of study populations (P0.01). Based on multivariate analysis, the significant factors associated with the presence of cirrhosis, with or without hepatocellular carcinoma, in chronic hepatitis C patients were genotype 1b and age. In conclusion, these results underline that independent HCV outbreaks continue in HCV hyperendemic areas in Taiwan, concomitant with a changing relative prevalence of HCV genotypes in relation to age. Both the correlation of genotype 1b with age (cohort effect) and intrinsic properties of HCV genotypes are probably responsible for the association between genotype and the pathogenesis of HCV infection.

TT virus (TTV) is a newly isolated DNA virus from the serum of a patient with posttransfusion hepatitis of unknown etiology in 1997. To evaluate the clinical and molecular characteristics of TT virus (TTV) in a hepatitis C virus (HCV) and B (HBV) hyperendemic area (Masago), 200 residents were enrolled in the study. The sera were tested for alanine aminotransferase (ALT), HCV RNA and GB virus C/Hepatitis G virus (HGV) RNA, TTV DNA, HBsAg, anti-HCV and antibodies to HGV E2-protein (anti-E2). TTV DNA was positive in 99 of the 200 sera with a prevalence rate of 49.5%. The prevalence of HBsAg, anti-HCV, HCV RNA, HGV RNA, anti-E2 and HGV exposure (defined as positive for serum HGV RNA and/or anti-E2) was 38.9%, 69.5%, 64.5%, 17.0%, 25.5% and 39.5%, respectively. Neither clinical nor virological factors were associated with TTV viremia. The rate of ALT abnormality was significantly elevated in HCV RNA-positive (34.9%) than -negative (7.0%) residents (p0.001). HCV viremia was the only factor significantly associated with ALT elevation by multiple logistic regression (odds ratio: 6.96; 95% C.I.: 2.60-18.7). We concluded that in this HCV/HBV hyperendemic area, the prevalence of TTV DNA was high. No significant clinical factor was observed to be associated with TTV infection. TTV infection is not related to abnormal ALT levels and ALT abnormality was mainly attributable to HCV but not TTV, HBV or HGV infection.

Background: Cerebrovascular disease is one of the leading causes of death worldwide. Hepatitis C virus (HCV) infection, a well-accepted causal agent for liver-related diseases, has been reported to increase the risk for atherothrombosis. However, the association between HCV infection and cerebrovascular diseases remains inconclusive and the dose-response relationship between serum HCVRNA levels and cerebrovascular death has never been elucidated. Methods: This study enrolled 23,665 residents aged between 30–65 years in community during 1991–1992. They were personally interviewed using structured questionnaires and provided blood samples for various serological and biochemical testing at study entry. Those who were seropositive for antibodies against HCV (anti-HCV) were examined for serum HCVRNA levels. HCV genotypes were determined in participants who had detectable serum HCVRNA. Cerebrovascular deaths of participants during follow-up were ascertained by computerized linkage with National Death Certification profiles from 1991 to 2007 (ICD-9: 430–438). Person-years at risk were calculated for each person as time from enrollment date to either the date of death, or to the end of 2007, whichever came first. Cox proportional hazards models were used to estimate relative risks and 95% confidence intervals for magnitude of HCV after adjustment of other risk factors. Results: There were 240 cerebrovascular deaths with 361,171 person-years of follow-up, giving a mortality of 66.5 per 100,000 person-years in this population. The cumulative risks for cerebrovascular death were 1.0% and 2.7% for anti-HCV seronegatives and anti-HCV seropositives (p < 0.001). Participants seropositive for anti-HCV had increased risk of cerebrovascular death, with a multivariate-adjusted relative risk (95% confidence interval) of 2.27 (1.56–3.30). Elevated serum HCVRNA levels increased the risk for cerebrovascular death with dose-response trend (p < 0.001). The adjusted relative risks were 1.52 (0.67– 3.44), 1.73 (0.43–6.98), 2.31 (1.25–4.25), and 3.45 (1.76– 6.75) in corresponding to participants with serum HCVRNA level

This paper presents a SAS macro for a simulation study of comparing a new variant of hot-deck imputation with mean imputation for missing values, in which a simple algorithm proposed by Bebbington (Applied Statistics, 1975) for carrying out simple random sampling without replacement was employed to draw repeated random samples efficiently. A simulated example of drawing repeated random samples from a regional survey of obesity in school children was used to demonstrate the SAS macro.

In the analysis of complex survey data such as stratified multi-stage cluster samples, ignoring the design effects such as clustering and stratification usually will lead to erroneous conclusions. In this paper, we will demonstrate the consequences in the estimation of means and proportions by two examples from a stratified two-stage cluster sample. A brief review of methodology will be presented, and some suggestions on computational issues will be provided.

In 1979, a mass poisoning involving some 2,000 persons occurred in central Taiwan from cooking oil contaminated by polychlorinated biphenyls (PCBs) and their heat-degraded byproducts, including polychlorinated dibenzofurans (PCDFs). The responsible health department registered cases for clinical purposes between 1979 and 1983. The exposed persons are referred to as the "yucheng" (oil disease) cohort. PCBs and PCDFs are toxic chemicals widely dispersed in the environment and in human tissue, which persist long after exposure. The consequences of exposure to these agents are not well understood. We traced the cohort through December 31, 1991, and compared overall and cause-specific mortality of 1,837 "yucheng" subjects with age, gender, and calendar time-specific mortality rates for the Taiwan general population. Eighty-three deaths were identified from 23,404 observed person-years. Even though the overall standardized mortality ratio (SMR) was 0.8 (95% confidence interval (CI) 0.7-1.0), there was a substantial elevation in the mortality rate for chronic liver disease and cirrhosis (10 deaths, SMR = 2.7, 95% CI = 1.3-4.9). Mortality from malignant neoplasms and other causes was not significantly different from that of the Taiwan population. PCB/PCDF exposure appears to promote the development of severe liver disease, perhaps in combination with known risk factors such as infection with hepatitis B virus. Further follow-up of this young cohort is necessary to see if the consequences include hepatic cancer.

To investigate the genotype distribution of hepatitis C virus (HCV) in southern Taiwan, the sera from 56 patients with chronic HCV infection were studied. Twenty-nine patients were men and 27 were women. Age ranged from 22 to 65 years (mean, 47.3 +/- 11.4). Eighteen of them had chronic persistent hepatitis, 27 had chronic active hepatitis, and 11 had liver cirrhosis. HCV RNA was detected by reverse transcription-nested polymerase chain reaction using primers derived from the 5'-noncoding region. The genotypes of HCV were determined by amplification of the core region with the type-specific primers as described by Okamoto et al.. All sera were positive for HCV RNA. The prevalence rates of genotypes were as follows: 1b/II, 44.6%(25/56); 2a/III, 41.1%(23/56); 2b/IV, 3.6%(2/56); mixed 1b/I + 2a/III, 5.4%(3/56): mixed 1b/II + 2b/IV, 1.8%(1/56) and type unclassified 3.6%(2/56). The distribution of genotypes was not related to the patients' age, sex, and histological changes. Nevertheless, patients having past history of blood transfusion had a significantly higher rate of HCV type 2a/III infection (72.2% versus 34.2%, p.05, chi-square test). We concluded that both of the HCV genotypes 1 b/II and 2a/III are predominant types in southern Taiwan and regional HCV genotype distribution may differ even within this island. Selective transmission of specific genotypes may pass along different infectious routes.

Interferon alpha (IFN-alpha) has been indicated to be dramatically effective in some but not all patients with chronic hepatitis C virus (HCV) infection. We investigated prospectively 27 patients of chronic hepatitis C, 12 females and 15 males, treated with IFN-alpha for a better regimen of the therapy and for any effective predictor of response to the treatment. All patients were treated with 3 to 6 million units (MU) of recombinant IFN-alpha 2b (n = 15) or lymphoblastoid IFN-alpha (n = 12) given 3 times weekly for 12 to 36 weeks. Patients with normal alanine aminotransferase (ALT) value during therapy, who sustained this response throughout 6 months follow-up after treatment was completed, were grouped into the complete responders. Patients with normal ALT value during therapy but who relapsed after treatment completed, were grouped as partial responders. Non-responders were defined as patients without normal ALT value during therapy. The rates of complete response, partial response, and non-response were 29.6%, 40.8%, and 29.6%, respectively. The degree of response to IFN-alpha therapy was not related to age, sex, type of IFN-alpha, history of blood transfusion, the state of liver pathology, or pretreatment level of ALT value. The complete responsive rate to IFN-alpha was higher in patients treated with total dose above 215 MU [38.1% (8/21) vs. 0% (0/6), p = 0.06], in patients treated for at least 24 weeks [40% (8/20) vs. 0% (0/7), p0.05], and in patients with non-genotype 1b/II HCV infection [40% (8/20) vs. 0% (0/7), p0.05]. We concluded that IFN-alpha was effective in the treatment of chronic HCV infection, particularly in those other than HCV genotype 1b/II. A high-dose, and long-duration regimen may be recommended for better response of chronic hepatitis C to IFN-alpha therapy.

To elucidate the status of serum hepatitis B virus (HBV) DNA in HBsAg-positive hepatocellular carcinoma (HCC), 100 type B chronic liver disease (CLD) patients and 19 HCC patients were studied. The positive rate of serum HBV DNA in HBeAg-positive CLD patients was significantly higher than that in HBeAg-negative CLD patients, and the correlation between the presence of serum HBV DNA and patients' age showed a negative trend. In contrast, the positive rates of serum HBV DNA in HCC patients were not related to the status of HBeAg and age, and the positive rate of serum HBV DNA in HBeAg-negative HCC patients was significantly higher than that in HBeAg-negative CLD patients. Nevertheless, the serum concentrations of HBV DNA in HCC patients were significantly lower than those in CLD patients. These results suggest that replication of HBV in HCC patients might differ from that in CLD patients, and that persistent low-level HBV replication might be related to the presence of HCC.

Necrotizing fasciitis is a rare and rapid progression soft tissue infection. The only identifiable feature is tissue necrosis along a single fascia plane. Because the skin is initially spared, it is difficult for early recognition prior to extensive tissue destruction. Ultrasonography was used for early diagnosis of this infection in five cases. All 5 patients presented with severe cellulitis. Under the suspicion of necrotizing fasciitis, ultrasonography was performed before surgical debridement. Tissue biopsy was done for histological confirmation of the diagnosis. Three patients were proven to have necrotizing fasciitis and two cellulitis only. The ultrasonographic findings of necrotizing fasciitis included: 1) irregularity of the fascia; 2) abnormal fluid collections along the fascia plane; and 3) diffuse thickening of the fascia when compared with the control site in the normal limb. However, in severe infectious cellulitis, the above mentioned findings were not observed. Our results indicate the usefulness of the ultrasonography for early diagnosis of necrotizing fasciitis.

A fully functional electron beam microcolumn, 3.5 mm in length, demonstrating a probe size of 10 nm and beam current >= 1 nA at 1 keV has been successfully developed. This paper presents its current status and future directions. Potential applications ranging from low cost scanning electron microscopy to arrays of such microcolumns for lithography, metrology, testing etc. will be discussed.

Neutrophils (PMN) from 20 patients with atopic disease (atopy), the parents of 8 of the patients and 10 normal controls were studied by light-microscopic cytochemistry. The results revealed that myeloperoxidase (MPO) and acid phosphatase (ACP) activities in PMN in all cases significantly decreased and alkaline phosphatase activity was normal. Parents or parent of 7 of those patients had PMN enzyme deficiency similar to that of the patients. The results indicated that a primary combined and partial deficiency of MPO and ACP in PMN azurophilic granule existed in atopy. It is postulated that the deficiency led to reduction of PMN bactericidal power and delay of bactericidal action. Foreign bodies which were partially degraded could possess antigenic property. This is believed to be the important cytobiological mechanism of the tendency toward infections and formation of sensitive antigen in atopy.

The neutrophils in 2 patients with atopic disease were studied. Ultrastructurally, a number of abnormal azurophilic granules (AG) with low electron-density (Case 1) and secondary lysosomes with "myelinoid membranes" figures (Case 2) were found. Myeloperoxidase (MPO) and acid phosphatase activity were detected by light cytochemical techniques, and showed significantly low values. The deficiency of MPO and abnormal distribution of AG were also demonstrated by electron microscopic cytochemical technique. The neutrophils from the parents revealed changes similar to the patients. This study suggests that since genetic partial deficiency of neutrophil AG enzymes existed, the phagocytosed substances were only partially degraded, leading to accumulation of substances with antigenicity, and became trigger event of atopic disease.

Vanadium pentoxide (V2O5) nanomaterials with various morphologies were prepared by chemical vapour deposition at a relatively low temperature (evaporation temperature of 250 °C and growth temperature of 500 °C) using vanadyl acetylacetonate (VO(acac)2) powder as the vanadium precursor. The obtained samples were characterized by scanning electron microscopy, x-ray diffraction, Raman scattering and photoluminescence spectra. The results revealed that the samples including a V2O5 nanocluster film, V2O5 nanowires and V2O5 nanospheres were synthesized at different distances from the source material. For our chemical vapour transport system, we suggested that VOx vapour and VO(acac)2 vapour existed simultaneously during the growth process, which resulted in different morphologies of V2O5 nanomaterials. The quite different supersaturation distributions of VOx vapour and VO(acac)2 vapour led to three main growth areas. The V2O5 film was grown in the region where the supersaturation of the VOx vapour was high, V2O5 nanowires were obtained where the supersaturation of the VOx vapour was relatively low and V2O5 nanospheres were synthesized in the region where the supersaturation of the VO(acac)2 vapour was high. The growth pressure that influenced the vapour concentration controlled the morphologies of the nanowires. It was found that a specific level of low concentration was necessary to ensure the growth of V2O5 nanowires.

To investigate the effect of obesity at diagnosis on prognosis of renal cell carcinoma, 360 renal cell carcinoma patients newly diagnosed at 29 hospitals in Oklahoma between January 1, 1981 and December 31, 1984 were followed through December 31, 1987. The Cox proportional-hazard model was used to estimate the hazard ratio, adjusting for other potentially prognostic factors. Both the disease-free interval and the overall survival were longer in patients who were obese (greater than or equal to 120% standard body mass index) at diagnosis. The adjusted-hazard ratio for disease recurrence between obese and nonobese patients was 0.43 (95% confidence interval [CI], 0.19 to 0.98). The obese patients had an adjusted death hazard rate 0.68 times that of the nonobese patients (95% CI, 0.38 to 1.22). Although obesity was reported to increase the risk for renal cell carcinoma, prognosis was no worse and may be better among obese patients with the disease.

Photoemission has often been proposed as a promising approach for achieving arrays of independently modulated photocathodes for electron-beam lithography applications. In most such proposals the modulation of the photocurrent is assumed to be achieved by controlling the incident light energy reaching each photocathode. For many applications, however, the optical complexity of such a scheme limits the attractiveness of the photocathode approach. In this article we propose a novel gated photocathode structure which resolves this concern. It allows stable and reproducible electrical modulation of the photocurrent from each photocathode in a thin-film array under continuous optical illumination. In addition, by using illumination of the photocathodes through a transparent substrate, the position, the size, and the shape of each photocathode can be accurately determined during fabrication rather than being determined by the size of the optical illumination spot on the photocathode material. A number of structu...

Experimental measurements of emission stability and energy distributions from a Schottky emitter have been conducted at a tip temperature range from 1330 to 1800 K. The changes of emission properties have been observed at reduced tip temperatures. Noise fluctuations of the probe current increase with decrease of the tip temperature at a constant extraction voltage. The work function of the Schottky emitter increases with decrease of tip temperature. The energy distribution measurements show that the energy width at a given temperature increases with increasing angular emission current density. The energy width also increases with decreasing tip temperature at a given angular emission current density. The results indicate that the energy broadening is mainly contributed by electron tunneling. A comparison of the measured energy width with the theoretical predictions is discussed.

Lithography with an array of miniaturized scanning electron‐beam columns presents one of the most promising high‐throughput possibilities for fabrication of devices with feature sizes less than 100 nm. With scanning electron beams no mask is required and the necessary resolution and alignment of overlay structures are realizable. With arrays of microcolumns, the lithography throughput of a single column can be multiplied. The approach can also be used for a number of lithography related applications such as metrology, inspection, testing, etc. We review the status of the microcolumn program and discuss opportunities and challenges of this approach to high‐throughput nanolithography and related applications. Special emphasis is given to lithography in the 100 nm regime.

A miniaturized 1 kV electron beam column with a 20×20 mm square footprint for application in arrayed lithography was developed. The actual beam forming optics measured from the electron emitter to the last electrode in the beam focusing Einzel lens is only 3.5 mm in length. The electron source is a miniaturized, high brightness (120 μA/sr), low heating power (

We have measured the energy distributions of electrons field emitted from tungsten carbide, HfC〈100〉, and ZrC〈100〉 tips, and tungsten field emitters with diamondlike carbon coatings. Multiple‐peaked energy distributions were observed from instability induced emission sites on the carbide tips. Energy distributions of electrons field emitted from the diamondlike carbon coated tungsten tips were broader than those from metal tips. They also showed a shift towards lower energies with increases in the emission current.

We have evaluated the cold‐field‐emission characteristics of HfC〈100〉 and ultrasharp tungsten emitters. We found that proper acetylene treatment improved both the angular current confinement and the emission stability of thermally cleaned HfC〈100〉 tips. Stable emission exceeding 10 μA/sr for over 1 h and angular confinement to a 3° semicone angle have been observed. The improvements are probably related to the modified work function and surface chemical composition induced by the acetylene treatment at the tip apex. Carburization of W〈100〉 and W〈111〉 tips also significantly improved the emission current stability. This study indicates the usefulness of surface processing in the development of cold‐field emitters.

A miniature Schottky electron source has been developed and evaluated for applications in a new generation of scanning tunneling microscope aligned field emission microcolumns. Both the physical dimensions and the heating power of this source have been significantly reduced from a conventional source of the same kind. Operating parameters for such a source in a microcolumn environment in terms of emission characteristics, suppressor operating range, etc., have been evaluated. Test results show that very good emission stability at ≥100 μA emission current over several hours, and axial angular current densities in excess of 100 μA/sr can be obtained. Energy distributions have been measured using a carefully calibrated analyzer, and the results show a full width at half‐maximum of 0.4 to 0.76 eV for a 0.3 μm radius Schottky source operating over an angular current density range of 1 to over 100 μA/sr. A significant change in the shape of the energy distribution was observed over this range of operation, indi...

We have built and tested a 1 keV electron‐beam microcolumn that focuses 1 nA of beam current into a 10 nm full width half‐maximum beam diameter at a working distance of 1 mm. The electron source is a miniaturized Zr/O/W Schottky field emitter with 150 μA/sr angular emission current density operating at about 1800 K at a distance of only 100 μm from a silicon membrane extractor electrode. The actual microcolumn is 3.5 mm long assembled mainly from silicon membrane electrodes. Improved einzel lens design and fabrication allowed the operation of this beam focusing element in the accelerating mode. Spherical and chromatic aberrations were reduced by factors of about 2–3, respectively, as compared to the retarding lens mode. Excellent beam current stability with less than 1% variation over several hours has been observed.

Schottky emission tips have been evaluated with microlenses for applications in scanning tunneling microscope aligned field emission microcolumns. Operation of Zr/O/W 〈100〉 Schottky emission tips at 1800 K with an axial separation of 50–100 μm between the tip and a microlens has been successfully tested. The microlens consists of an extraction electrode with a 5‐μm‐diam hole in a 1‐μm‐thick silicon membrane. The preliminary results of this study show that thermal field emission tips can be operated continuously in close proximity to a microlens over a long period of time, and that good emission stability of less than 1% noise fluctuation over 10 h is achieved with emission currents up to at least 100 μA.

We have examined the field emission characteristics of oxygen‐processed and thermal‐field buildup W 〈111〉 tips. Good emission angular confinement was found to correlate with the global geometry of the tip. Emission stability was related to the atomic arrangement at the apex. This phenomenon is described by the different driving forces for atomic surface diffusion. We also showed that tip apexes can be engineered to form flat (111) facets at the tip end for improved stability.

An oxygen induced sharpening process of field emitter tips, W〈111〉, for use in a scanning tunneling microscope aligned field emission microcolumn system has been developed. The sharpening process which depends on processing temperature and oxygen pressure can be used to control tip radius accurately with reliability and reproducibility. The measured tungsten removal rate was ∼13 A/min at a processing temperature of ≂1650 K and at an oxygen pressure of ≂4×10−5 Torr. The process is primarily intended for more accurate control of the tip radius and hence performance of newly etched tips, although damaged or blunt tips can also be resharpened in situ with this process. Favorable emission characteristics of the oxygen processed tips have been observed with microcolumn operation: (1) reasonably stable emission current, (2) low extraction voltage, (3) reproducible threefold symmetric emission patterns, and (4) small emission angle.

A three-dimensional close-packed array of Josephson junctions was successfully produced in the form of a bulk granular superconductor. The granular system is a tightly compressed solid of oxide coated small tin particles in the thousand A range. The three-dimensional array of Josephson junctions thus formed showed coherent Josephson oscillations when external rf radiation was imposed, rf induced constant voltage steps were observed on its I-V characteristics at voltages a few thousand times the Josephson voltage hv/2e. The external rf radiation also induced Stable dc voltages on unbiased bulk samples, suggesting a practical mode of microwave detection. The analogy of this bulk superconducting system with a magnetic spin system will be discussed.

Common ion sputtering techniques for depth profiles can cause buildup of charge in low‐conductivity regions such as p‐n junctions in semiconductors, leading to erroneous results. We analyzed Ga0.1Al0.9As liquid phase epitaxial (LPE) layers on GaAs with secondary ion mass spectrometry (SIMS) and observed that the profiles of 69Ga+ and 27Al+ in the low‐conductivity region of these Zn‐diffused LPE layers were a function of the sample bias. We noticed that this artifact was due to the shift and broadening of the secondary ion energy distributions caused by positive charging of the specimen surface. We also found that this could be effectively remedied by integrating the secondary ion yields over a wide energy range. The use of an electron flood gun reduced this charging effect, but complete charge compensation was not achieved even at electron current densities far exceeding the ion current density. This can be explained by the fact that the electron‐induced secondary electron coefficient of GaAlAs is larger ...

The emission of positive atomic secondary ions from single phase binary alloys during 15 keV Ar+ bombardment was studied in an ultrahigh vacuum environment. For all the five alloy systems: Fe–Ni, Cu–Ni, Pd–Ni, Al–Ni, and Si–Ni, the ionization probabilities of the elements show little or no correlation with the bulk alloy density of states or the local density of states near the Fermi level. When the ionization probabilities are compared with the electronegativity differences of the elements, we notice that only the emission of Al+ and Ni+ from Al–Ni alloys seems to follow the direction of the anticipated charge transfer.

The transport of ATP out of mitochondria and uptake of ADP and Pi into the matrix are coupled to the uptake of one proton (Klingenberg, M., and Rottenberg, H. (1977) Eur. J. Biochem. 73, 125--130). According to the chemiosmotic hypothesis of oxidative phosphorylation this coupling of nucleotide and Pi transport to proton transport implies that the P/O ratio for the synthesis and transport of ATP to the external medium is less than the P/O ratio for the synthesis of ATP inside mitochondria. A survey of previous determinations of the P/O ratio of intact mitochondria showed little convincing evidence in support of the currently accepted values of 3 with NADH-linked substrates and 2 with succinate. We have measured P/O ratios in rat liver mitochondria by the ADP pulse method and by 32 Pi esterification, measuring oxygen uptake with an oxygen electrode, and find values close to 2 with beta-hydroxybutyrate as substrate and 1.3 with succinate as substrate in the presence of rotenone to inhibit NADH oxidation. These values were largely independent of pH, temperature, Mg2+ ion concentration, Pi concentration, ADP pulse size, or amount of mitochondria used. We suggest that these are the true values of the P/O ratio for ATP synthesis and transport by mitochondria, and that previously reported higher values resulted from errors in the determination of oxygen uptake and the use of substrates which lead to ATP synthesis by succinate thiokinase.