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Polarization switching in ferroelectric films is exploited in many applications, such as non-volatile memories and negative capacitance field affect transistors. This can be inhomogeneous or homogeneous, depending on if ferroelectric domains are forming or not during the switching process. The relation between the polarization switching, the structural quality of the films and the negative capacitance was not studied in depth. Here, Pb(Zr0.2Ti0.8)O3 (PZT) layers were deposited by pulse laser deposition (PLD) and sol-gel (SG) on single crystal SrTiO3 (STO) and Si substrates, respectively. The structural quality was analyzed by X-ray diffraction and transmission electron microscopy, while the electric properties were investigated by performing hysteresis, dynamic dielectric measurements, and piezo-electric force microscopy analysis. It was found that the PZT layers grown by PLD on SRO/STO substrates are epitaxial while the layers deposited by SG on Pt/Si are polycrystalline. The polarization value decreases as the structure changes from epitaxial to polycrystalline, as well as the magnitude of the leakage current and of the differential negative capacitance, while the switching changes from homogeneous to inhomogeneous. The results are explained by the compensation rate of the depolarization field during the switching process, which is much faster in epitaxial films than in polycrystalline ones.

Composites of magnetite (Fe3O4) nanoparticles dispersed in a polydimethylsiloxane (PDMS) matrix were prepared by a molding process. Two types of samples were obtained by free polymerization with randomly dispersed particles and by polymerization in an applied magnetic field. The magnetite nanoparticles were obtained from magnetic micrograins of acicular goethite (α-FeOOH) and spherical hematite (α-Fe2O3), as demonstrated by XRD measurements. The evaluation of morphological and compositional properties of the PDMS:Fe3O4 composites, performed by SEM and EDX, showed that the magnetic particles were uniformly distributed in the polymer matrix. Addition of magnetic dispersions promotes an increase of thermal conductivity compared with pristine PDMS, while further orienting the powders in a magnetic field during the polymerization process induces a decrease of the thermal conductivity compared with the un-oriented samples. The shape of the magnetic dispersions is an important factor, acicular dispersions providing a higher value for thermal conductivity compared with classic commercial powders with almost spherical shapes.

Structural and electrical properties of epitaxial Pb(Zr0.2Ti0.8)O3 films grown by pulsed laser deposition from targets with different purities are investigated in this study. One target was produced in-house by using high purity precursor oxides (at least 99.99%), and the other target was a commercial product (99.9% purity). It was found that the out-of-plane lattice constant is about 0.15% larger and the a domains amount is lower for the film grown from the commercial target. The polarization value is slightly lower, the dielectric constant is larger, and the height of the potential barrier at the electrode interfaces is larger for the film deposited from the pure target. The differences are attributed to the accidental impurities, with a larger amount in the commercial target as revealed by composition analysis using inductive coupling plasma-mass spectrometry. The heterovalent impurities can act as donors or acceptors, modifying the electronic characteristics. Thus, mastering impurities is a prerequisite for obtaining reliable and reproducible properties and advancing towards all ferroelectric devices.

Temperature dependent interfacial coupling mechanisms in SRO/BFO/Fe layered structures were investigated. The BFO/Fe heterostructures were prepared by PLD and sputtering, respectively, on the STO(0 0 1) substrate with a 20 nm SRO buffer layer. An annealing treatment in external magnetic field was further applied. Complex characterizations with X-ray diffraction, atomic force microscopy, Transmission Electron Microscopy, Mossbauer spectroscopy, magneto-optic Kerr effect and SQUID magnetometry were performed. Before annealing, the films show good crystallization and epitaxy of the SRO and BFO layers with smooth interfaces. Two coupling mechanisms of the ferromagnetic layers (top Fe and bottom SRO, respectively) to the epitaxial BFO film with mainly antiferromagnetic structure were evidenced in the as deposited samples at low temperatures. Negative exchange bias fields of up to 67(10) Oe and 37(5) Oe at low temperatures were observed for the two ferromagnetic components, respectively, depending on the thickness of the Fe layer. The field annealing treatments induce a specific morphology and magnetic spin structure at both interfaces of the BFO spacer layer, giving rise to a long range magnetostatic coupling between the two ferromagnetic films, in addition to the interfacial couplings. Moreover, the experimentally evidenced Fe clusters penetrating the BFO/Fe interface toward the BFO layer give support for this interaction. As an additional consequence, a considerable enhancement of both uniaxial and unidirectional anisotropies as well as an increased blocking temperature of exchange bias were obtained. The involved exchange coupling mechanisms were discussed in detail.

Ferroelectric field effect transistors (FeFETs) based on lead zirconate titanate (PZT) ferroelectric material and amorphous-indium-gallium-zinc oxide (a-IGZO) were developed and characterized. The PZT material was processed by a sol-gel method and then used as ferroelectric gate. The a-IGZO thin films, having the role of channel semiconductor, were deposited by radio-frequency magnetron sputtering, at a temperature of ~50°C. Characteristics of a typical field effect transistor with SiO2 gate insulator, grown on highly doped silicon, and of the PZT-based FeFET were compared. It was proven that the FeFETs had promising performances in terms of Ion/Ioff ratio (i.e., 106) and IDS retention behavior.

Ba0.75Sr0.25TiO3 (BST) and PbZr0.68Fe0.14Nb0.14Ti0.04O3 (PZFNT) ceramic pellets were obtained by ceramic technology and their structural, ferroelectric and pyroelectric properties were investigated. The relative density of BST and PZFNT is about 93% and 90%, respectively, with an average grain size of 102 ?m and 6.45 ?m. Both materials have similar room temperature dielectric constants (~2000), but PZFNT shows higher remnant polarization (~15?C/cm2) and better pyroelectric properties (~1.69?10?4 C/m2K), which recommend it for pyroelectric detectors, infrared radiation- and laser pulse energy-meters.

The integration of ferroelectrics in perovskite solar cells is proposed as possible way to enhance charge collection efficiency. First results on solar cell manufactured with PbTiO3 (PTO) instead of TiO2 have shown negligible values for the power conversion efficiency (PCE). This is explained by the high serial resistance of sol-gel deposited PTO on F:SnO2 electrodes (FTO). Although PTO layer has remnant polarization of 22 μC/cm2, the high potential barrier (0.25 ± 0.05 eV) at the FTO/PTO interface and low carrier mobility (10−8 cm2 V−1 s−1) compared to TiO2 leads to high serial resistance. Better results were obtained with thinner PTO layers grown by pulsed laser deposition, with PCE values up to 0.6%. Further enhancement was obtained by replacing PTO with BaTiO3 (BTO), with PCE value reaching about 0.8% after poling the cell with +3 V. The most important finding was that the magnitude of the short circuit current increases with the amplitude of the poling voltage while the value of the open-circuit voltage remains about the same, around 0.9 V. This is explained through more efficient collection of the charges generated under illumination in the absorber layer due to the polarization that is present in the ferroelectric film. Keywords: Ferroelectric, Perovskite, Solar cell, Polarization

Hysteretic effects are investigated in perovskite solar cells in the standard FTO/TiO2/CH3NH3PbI3–xClx/spiro-OMeTAD/Au configuration. We report normal (NH) and inverted hysteresis (IH) in the J–V characteristics occurring for the same device structure, and the behavior strictly depends on the prepoling bias. NH typically appears at prepoling biases larger than the open circuit bias, while pronounced IH occurs for negative bias prepoling. The transition from NH to IH is marked by an intermediate mixed hysteresis behavior characterized by a crossing point in the J–V characteristics. The measured J–V characteristics are explained quantitatively by the dynamic electrical model. Furthermore, the influence of the bias scan rate on the NH/IH hysteresis is discussed based on the time evolution of the accumulated ionic and electronic polarization charge at the interfaces. Introducing a three-step measurement protocol, which includes stabilization, prepoling, and measurement, we put forward the difficulties and pos...

In this paper, potassium based triple cation mixed-halide perovskite films were explored in order to enhance the stability and photovoltaic performance of perovskite based solar cells. It was found that adding potassium (K+) to a double cation mixed halide perovskite (FA0.80MA0.20PbI2.8Cl0.2), structural, morphological and optoelectronic properties of perovskites are improved. The perovskite films were prepared by one-step spin coating method with and without K+ and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and photoluminescence spectroscopy (PL). The results indicate that potassium incorporation reduces significantly the yellow non-perovskite δ-phase formation and improves the perovskite film quality, thus contributing to the reduction of hysteresis, improves the stability and increases the PCE up to 12.51%. Furthermore, the doped devices exhibit reduced hysteresis and provide remarkable shelf stability by retaining more than 70% of the initial efficiency with low humidity over 850 h.

We monitored the evolution in time of pinhole-free structures based on FTO/TiO2/CH3NH3PbI2.6Cl0.4 layers, with and without spiro-OMeTAD and counter electrodes (Ag, Mo/Ag, and Au), aged at 24 °C in a dark nitrogen atmosphere. In the absence of electrodes, no degradation occurs. While devices with Au show only a 10% drop in power conversion efficiency, remaining stable after a further overheating at 70 °C, >90% is lost when using Ag, with the process being slower for Mo/Ag. We demonstrate that iodine is dislocated by the electric field between the electrodes, and this is an intrinsic cause for electromigration of I– from the perovskite until it reaches the anode. The iodine exhaustion in the perovskite layer is produced when using Ag electrodes, and AgI is formed. We hypothesize that in the presence of Au the iodine migration is limited due to the buildup of I– negative space charge accumulated at the perovskite–OMeTAD interface.

The pyroelectric coefficient of some Pb(Zr,Ti)O3 type ceramics was estimated using two methods: a direct method, based on the temperature dependence of the charge/current generated by pyroelectric effect; an indirect method based on the frequency dependence of the pyroelectric signal generated by a pyroelectric element under modulated irradiation with infrared light. The purpose was to compare the results and to assess if the indirect method is enough accurate for rapid estimation of the pyroelectric coefficient of a material envisaged for infrared detection. The direct method is more accurate and requires accurate control of temperature and heating rate, while the indirect method is less accurate, with an error up to 20%, and requires the knowledge of quantities such as dielectric constant, electric conductance, and incident power. However, the indirect method can be more easily implemented and can provide a rapid assessment on the pyroelectric quality of a material with potential use in infrared detectors.

The current–voltage ( C-V ) characteristic of epitaxial ferroelectric films is simulated assuming the presence of Schottky-type contacts at the two electrode interfaces. The model assumes that the overall capacitance of the metal-ferroelectric-metal ( MFM ) structure is composed of two parts: (i) one associated with the Schottky contacts, in which the ferroelectric polarization is saturated, the dielectric constant is independent on the voltage and only the linear response to the applied electric field is taken into account; (ii) one related to the ferroelectric volume, where the dielectric constant is voltage dependent through the hysteresis response of the ferroelectric polarization. The most important result of the model is that it can simulate the experimentally observed thickness dependence of the dielectric constant without considering a so-called “dead layer” at the electrode interface. The model renders C-V characteristics in good qualitative agreement with the experimental ones in the case of an MFM structure based on epitaxial PZT films. The quantitative fit suggests that the behaviour of the ferroelectric polarization during the C-V measurement may be very different from its behaviour during the hysteresis measurement. This is explained by the fact that the two measurements have very different principles. It is also found that the dielectric constant of the ferroelectric volume has a different voltage dependence compared to the one derived from the hysteresis loop or from the experimental C-V characteristic. This is also related to the different measurement principles and to the fact that the measured capacitance of the MFM structure includes, besides the ferroelectric volume, the voltage dependent capacitance of the Schottky contacts.

We investigate in how far the hysteresis-free behavior of perovskite solar cells can be reproduced using particular pre-conditioning and measurement conditions. As there are currently more and more reports of perovskite solar cells without J-V hysteresis it is crucial to distinguish between genuine performance improvements and measurement artifacts. We focus on two of the parameters that influence the dynamic J-V scans, namely the bias scan rate and and the bias poling voltage, and point out measurement conditions for achieving a hysteresis-free behavior. In this context we discuss the suitability of defining a hysteresis index (HI) for the characterization of dynamic J-V scans. Using HI, aging effects are also investigated, establishing a potential connection between the sample degradation and the variation of the maximal hysteresis on one hand, and relaxation time scale of the slow process, on the other hand. Pre-poling induced recombinations effects are identified. In addition, our analysis based on sample pre-biasing reveals potential indication regarding two types of slow processes, with two different relaxation time scales, which provides further insight regarding ionic migration., Comment: 11 pages, 11 figures

The results of the electric and magnetic measurements performed on PbZr0.2Ti0.8O3–BiFeO3 symmetric structures, deposited on Pt/Si wafers, were compared for different number of layers in order to analyse the effect of interfaces over the macroscopic properties. It was found that the shape and magnitude of the capacitance–voltage characteristic, as well as the shape and parameters of the ferroelectric and magnetic hysteresis, depend on the number of interfaces in the intended multilayer structure. A temperature induced gradual transition from a magnetically disordered spin glass like phase of low temperature to an uncompensated antiferromagnetic phase at room temperature takes place in the BiFeO3 films, under low applied magnetic fields. A partial ferromagnetic like order can be obtained at low temperatures by increasing the field. The observed changes in the electric and magnetic behaviour of the systems were related to an increased degree of disorder for electric dipoles and magnetic moments, due to the increased number of layers and crystallization treatments.

PbZr 0.2 Ti 0.8 O 3 -BiFeO 3 -PbZr 0.2 Ti 0.8 O 3 (PZT-BFO-PZT) structure was prepared by sol-gel method on Pt/Si wafers. Three metals were tested as top electrod: Au, Cu, and Pt. A double hysteresis loop was observed in all cases, suggesting an antiferroelectric-like behavior. The values for remnant polarization and coercive field are about 3 μC/cm 2 and 115 kV/cm, respectively. The saturation polarization is about 22 μC/cm 2 . Capacitance and leakage current show significant dependence on the top metal electrode. The results were explained considering the presence of a Schottky-type contact at the PZT-metal interface.

The influence of the gate voltage on photoconductivity in p–Si/SiO 2 /(nano)crystalline PbS, Metal-Oxide Semiconductor Field-Effect Transistor (MOSFET ) -like structures is investigated. The effect on the photo-signal in the wavelength range 500–1180 nm is opposite compared to the effect in the wavelength range 1600–2500 nm: a negative gate voltage increases the signal in the short wavelength range and decreases it for the long wavelength range. The opposite is valid for a positive gate bias. An on-off ratio better than 85 times is obtained for the spectral range 500–1180 nm, corresponding to the absorption in p–Si and better than 3.5 times for the spectral range 1600–2500 nm corresponding to the absorption in the (nano)crystalline PbS region, respectively.

The nano-crystalline PbS/ n -Si heterostructure was studied using photocurrent spectra, I – V and C – V characteristics and admittance spectroscopy. The frequency dependent junction capacitance and conductance measurements show the presence of two contributions: first, a defect related mechanism which we attribute to a deep trap level with a large cross-section in nano-crystals with smaller sizes around 5 nm at the interface with Si and a second mechanism with an activation energy of about 250 meV, attributed to carrier transport in relatively large PbS grains of about 15 nm in size.

The sol–gel deposition method has been successfully applied to obtain Pb(Zr0.2Ti0.8)O3 thin films on platinized silicon wafers. Addition of different amounts (7–15 wt.%) of organic macromolecular polyvinylpyrrolidone in the precursor solution prior to spin coating proves to be an excellent method for obtaining porous films. The crystal structure of as deposited films was analyzed by X-ray diffraction. The porous films show perovskite phase after annealing at 650 °C. The surface morphology has been studied by Atomic Force Microscopy and Scanning Electron Microscopy. The surface profile indicates a roughness of the film of 5 nm and no microcracks on the surface. The ferroelectric behavior was proved for each film, by hysteresis loops and by the “butterfly” shape of the capacitance–voltage characteristics. The remnant polarization and the coercive field decrease while the amount of added PVP increases.

In this work we present a model for magnetic domain wall (DW) dynamics in metallic ferromagnets with uniaxial anisotropy. The model allows us to consider both viscous and eddy current dampings. While the latter mechanism involves only one degree of freedom — the coordinate of the DW, the former involves all degrees of freedom of the spins in magnetic domains and in DW’s. The structure of the DW itself must then be considered, the conjecture used allowing one to describe the spin precessions which may appear in low quality factor Q materials. The model built is nonlinear, allowing one to deal with the set of complex susceptibilities characterizing the response to an ac drive field in strongly nonlinear circumstances, and has a general character, due to the normalized quantities used. In this work we analyze the susceptibility and the dissipated power spectra as functions of a dc transversal field, which can be treated only by this kind of models. We show that the viscous damping can become comparable to eddy current damping when precessions are excited.

A population study was carried out on 301 ethnic Germans from Dusseldorf (Northrhine Westphalia) using the short tandem repeat (STR) system HumF13B (Coagulation Factor XIIIB). Five different alleles were detected. No deviations from the Hardy-Weinberg equilibrium could be observed. In spite of the successfulness of the system only a few population data exist. A pooled sample from Northrhine Westphalia has to be used as preliminary database for forensic and anthropological purposes.

Hypervariable loci within the human genome are useful tools in several disciplines: for example in forensic medicine (paternity testing and forensic identification). One of these genetical markers is located at chromosome 1 and is called D1S80 (MCT118). The genotype distribution and the allele frequency of the VNTR locus D1S80 have been studied in a population of 378 unrelated Germans living at Düsseldorf. The determination of genotypes has been carried out by using the polymerase chain reaction and subsequent analysis of the amplified products by polyacrylamide electrophoresis followed by silver staining. The data demonstrate that the locus is highly polymorphic with an observed heterozygosity of 75.66%. The frequency distribution found does not meet Hardy-Weinberg expectations. We think that this is not astonishing because we found only 80 of the possible 231 phenotypes (alleles 16-34, 36-37, without anodal and cathodal variants). So before using the D1S80 data in forensic analyses and paternity tests a larger data base has to be established. The data of the Düsseldorf sample are compared with data of studies on other populations.

A single ferroelectric Schottky diode was obtained on a ${\text{SrRuO}}_{3}\text{-Pb}({\text{Zr}}_{0.2}{\text{Ti}}_{0.8}){\text{O}}_{3}\text{-Ta}$ (SRO-PZT20/80-Ta) structure in which the SRO-PZT20/80 interface is the rectifying contact and the PZT20/80-Ta interface behaves as a quasiohmic contact. Both the capacitance-voltage $(C\text{\ensuremath{-}}V)$ and the current-voltage $(I\text{\ensuremath{-}}V)$ characteristics show the memory effect due to the ferroelectric polarization. However, retention studies had revealed that only the ``down'' orientation of ferroelectric polarization is stable in time (polarization oriented from top to bottom contact). The analysis of the experimental results suggests that the PZT20/80 is $n$ type and that the stable orientation of polarization is related to the presence of a depletion region at the SRO-PZT20/80 Schottky interface.

A comparative study of photodetector performance for nano- and micro-crystalline PbS thin layers is presented. Both types of PbS films were obtained using the Chemical Bath Deposition method. To prepare nano-crystalline thin films we used a short reaction time with no doping Bi added. At low levels of irradiance (0.1 m W/cm2) and room temperature (RT), the macro-crystalline PbS outperforms its nano- crystalline counterpart, by a factor of 6 for the value of DeltaR/Rdark However the nano-crystalline photodetectors show significantly lower optical quenching for large values of irradiance (ap 500 mW/cm2) at RT and better DeltaR/Rdark performance at lower temperature, with an optimum temperature of 150 K. The low frequency noise behavior is a superposition of 1/f flicker noise at low frequency and generation-recombination and thermal noise at higher frequency. The proportionality factor between the 1/f noise and the DC dark current for the series resistor is 1.5 times larger for the nano-crystalline photodetector at room temperature.

The mechanism of charge storage in p Si/SiO2 /nano-crystalline PbS heterostructures is investigated using capacitance - voltage (C-V) and conductance-voltage (G-V) measurements at different frequencies. The nano-crystalline thin PbS films were obtained using the Chemical Bath Deposition method with a shorter reaction time and without doping element in the reducing bath. The C-V curves show hysterezis indicating charge storage with a maximum charge density of 3×1011 cm?2 for the highest measurement frequency of 100 kHz. The charge storage capacity is enhanced in the case of using a nano-crystalline PbS thin film instead of a standard macro-crystalline film.

A population study was carried out on 301 ethnic Germans from Düsseldorf (Northrhine Westphalia) using the short tandem repeat (STR) system HumF13B (Coagulation Factor XIIIB). Five different alleles were detected. No deviations from the Hardy-Weinberg equilibrium could be observed. In spite of the successfulness of the system only a few population data exist. A pooled sample from Northrhine Westphalia has to be used as preliminary database for forensic and anthropological purposes.

To create a preliminary data base for the PCR based loci HUMVWA31, HUMTH01, HUMFES/FPS, HUMF13B AND D1S80 population data from Germany were collected and additional population studies have been carried out on ethnic Germans living in Northrhine Westphalia. With exception of the D1S80 system no deviations from the Hardy-Weinberg-equilibrium have been detected. The German samples have been pooled by calculating the weighted arithmetical means to be useful as preliminary data base for forensic purposes.

The short-circuit photocurrent was measured in ferroelectric capacitors of polycrystalline and epitaxial quality. The interest was to study the possible relation between photocurrent and back-switching phenomena due to ferroelectric polarization imprint, as suggested by Pintilie et al. [J. Appl. Phys. 101, 064109 (2007)]. An interesting relation between the shape of the ferroelectric hysteresis loop and the shape of the photocurrent spectral distribution was found. In polycrystalline samples, the shape of spectral distribution and the sign of photocurrent are changing in time, although the hysteresis is almost symmetrical. However, the hysteresis is not rectangular as in the case of epitaxial films. This behavior suggests a subtle relation between polarization back-switching and photocurrent. In epitaxial samples a peculiar dependence between photocurrent and polarization imprint was found. All these are explained assuming the presence of an internal field, possibly generated by charged defects, which can...

Pt–ZnO–Pb(Zr0.2Ti0.8)O3–Pt (PZT-ZnO) heterostructures were fabricated by using a sol-gel process. Capacitance-voltage measurements performed on a wide temperature range (20–450 K) have revealed the presence of a hysteresis that undergo a change of direction from clockwise at temperatures below 350 K to counter-clockwise at higher temperatures. In the first case, the hysteresis is produced by charge injection, similar to the case of classical metal-oxide-semiconductor capacitors. In the last case, the hysteresis is the fingerprint of polarization reversal, as reported for metal-ferroelectric-semiconductor (MFS) structures based on n-Si. The memory window at 450 K is about 6 V. This result suggests that PZT-ZnO MFS heterostructures can be used for memory devices working at elevated temperatures, in which the ZnO plays the role of the semiconductor.

Orosomucoid or a1-acid glycoprotein is an acute phase reactant. It is coded by chromosome 9 (12) and its concentration increases in response to non-specific stimuli. The protein has a binding capacity for several drugs (2, 5, 9, 13, 17, 24, 25, 29). Clinical investigations did not lead to significant association with diseases (7,10,23). Numerous population data have been published (6, 15, 16, 22, 33, 34, 36, 37). Rare variants (11, 14, 19, 20, 21, 22, 31, 32, 36) have been reported using different improved techniques (4, 8, 14, 16, 18, 27, 28, 29, 30, 33, 38).

Leakage currents determine bumps in the capacitance-voltage characteristics of metal-oxide-semiconductor-type heterostructures with capacitance values larger than the insulator capacitance. A nearly parallel shift with frequency is also observed. These aspects are connected with the presence of a high density of interface states. We illustrate these effects for the case of nano-PbS∕SiO2∕Si heterostructures. The phenomena were simulated and we propose a method to quickly estimate the interface state density level of a heterostructure when leakage channels are present.

Pb(Zr1-xTix)O3 (PZT) thin films were prepared by sol-gel method on stainless steel (SS) an on platinum-coated silicon substrate (Pt/Si). The structure revealed by X-ray diffraction shows stron crystallographic orientation: (110) and (100), respectively. The crystallite size shows significa differences: d(SS)(001) = 27.1 nm, d(Pt)(h00) = 88 nm. The tetragonal splitting is (Δc/c)(SS) = 3.55 % an (Δc/c)(Pt) = 3.32 %. The ferroelectric hysteresis loop in the static mode is characterized by remanentpolarization of 25 μC/cm2 and coercive field of 45 kV/cm for SS substrate, while for Pt/Si substrate the values are 10 μC/cm2 and 39 kV/cm, respectively. The leakage current is about 3 orders of magnitude lower in the PZT film deposited on SS. The better properties of the PZT deposited on S are explained by the presence of large single crystal-like crystallites, which make the film closer to epitaxial ones. The results show the potential of growing epitaxial films on low-price substrates such as stainless-steel.

The paper reports on the distribution of three plasma protein systems in serum samples from 99 HIV-seropositive patients: Gc-subtyping, Tfc-subtyping and Pi- (alpha1-antitrypsin) system. In the Gc-system — as in further studies — we found evidence for non-association of Gc-subtypes — especially 1F — with HIV-infection. Also the distribution of Tfc-subtypes seems to be very similar to studies on healthy persons. In the Pi-system this pilot study led to the suspicion that the phenotype Pi*M2 is overrepresented. The distribution found in these patients is not comparable with the control group.

Tracing for ABH-Antigens on Chewing Gum 14 different chewing gum-brands were examined for their quality as trace carriers. Our examinations of freshly chewed gums resulted in distinction of ABH-antigens without greater difficulties by using absorption/elution and absorption/inhibition techniques. A simple method was developed to pulverize chewing gum for elution of the antigens.