Structural Parameters and Behavior in Simulated Body Fluid of High Entropy Alloy Thin Films

The structure, composition and corrosion properties of thin films synthesized using the Pulsed Laser Deposition (PLD) technique starting from a three high entropy alloy (HEA) AlCoCrFeNix produced by vacuum arc remelting (VAR) method were investigated. The depositions were performed at room temperature on Si and mirror-like polished Ti substrates either under residual vacuum (low 10-7 mbar, films denoted HEA2, HEA6, and HEA10, which were grown from targets with Ni concentration molar ratio, x, equal to 0.4, 1.2, and 2.0, respectively) or under N2 (10-4 mbar, films denoted HEN2, HEN6, and HEN10 for the same Ni concentration molar ratios). The deposited films' structures, investigated using Grazing Incidence X-ray Diffraction, showed the presence of face-centered cubic and body-centered cubic phases, while their surface morphology, investigated using scanning electron microscopy, exhibited a smooth surface with micrometer size droplets. The mass density and thickness were obtained from simulations of acquired X-ray reflectivity curves. The films' elemental composition, estimated using the energy dispersion X-ray spectroscopy, was quite close to that of the targets used. X-ray Photoelectron Spectroscopy investigation showed that films deposited under a N2 atmosphere contained several percentages of N atoms in metallic nitride compounds. The electrochemical behavior of films under simulated body fluid (SBF) conditions was investigated by Open Circuit Potential (OCP) and Electrochemical Impedance Spectroscopy measurements. The measured OCP values increased over time, implying that a passive layer was formed on the surface of the films. It was observed that all films started to passivate in SBF solution, with the HEN6 film exhibiting the highest increase. The highest repassivation potential was exhibited by the same film, implying that it had the highest stability range of all analyzed films. Impedance measurements indicated high corrosion resistance values for HEA2, HEA6, and HEN6 samples. Much lower resistances were found for HEN10 and HEN2. Overall, HEN6 films exhibited the best corrosion behavior among the investigated films. It was noticed that for 24 h of immersion in SBF solution, this film was also a physical barrier to the corrosion process, not only a chemical one.

Mechanical and Corrosion Behavior of Zr-Doped High-Entropy Alloy from CoCrFeMoNi System

The aim of the paper is to study the Zr addition effect on the mechanical properties and corrosion behavior of a high-entropy alloy from the CoCrFeMoNi system. This alloy was designed to be used for components in the geothermal industry that are exposed to high temperature and corrosion. Two alloys, one Zr-free (named Sample 1) and another one doped with 0.71 wt.% Zr (named Sample 2), were obtained in a vacuum arc remelting equipment from high-purity granular raw materials. Microstructural characterization and quantitative analysis by SEM and EDS were performed. The Young modulus values for the experimental alloys were calculated on the basis of a three-point bending test. Corrosion behavior was estimated by linear polarization test and by electrochemical impedance spectroscopy. The addition of Zr resulted in a decrease in the value of the Young modulus but also in a decrease in corrosion resistance. The beneficial effect of Zr on the microstructure was the grain refinement, and this ensured a good deoxidation of the alloy.

Study on the Weldability of Copper-304L Stainless Steel Dissimilar Joint Performed by Robotic Gas Tungsten Arc Welding

The welding process of dissimilar metals, with distinct chemical, physical, thermal, and structural properties, needs to be studied and treated with special attention. The main objectives of this research were to investigate the weldability of the dissimilar joint made between the 99.95% Cu pipe and the 304L stainless steel plate by robotic Gas Tungsten Arc Welding (GTAW), without filler metal and without preheating of materials, and to find the optimum welding regime. Based on repeated adjustments of the main process parameters-welding speed, oscillation frequency, pulse frequency, main welding current, pulse current, and decrease time of welding current at the process end-it was determined the optimum process and, further, it was possible to carry out joints free of cracks and porosity, with full penetration, proper compactness, and sealing properties, that ensure safety in operating conditions. The microstructure analysis revealed the fusion zone as a multi-element alloy with preponderant participation of Cu that has resulted from mixing the non-ferrous elements and iron. Globular Cu- or Fe-rich compounds were developed during welding, being detected by Scanning Electron Microscope (SEM). Moreover, the Energy Dispersive X-ray Analysis (EDAX) recorded the existence of a narrow double mixing zone formed at the interface between the fusion zone and the 304L stainless steel that contains about 66 wt.% Fe, 18 wt.% Cr, 8 wt.% Cu, and 4 wt.% Ni. Due to the formation of Fe-, Cr-, and Ni-rich compounds, a hardness increase up to 127 HV_0.2 was noticed in the fusion zone, in comparison with the copper material, where the average measured microhardness was 82 HV_0.2. The optimization of the robotic welding regime was carried out sequentially, by adjusting the parameters values, and, further, by analyzing the effects of welding on the geometry and on the appearance of the weld bead. Finally, employing the optimum welding regime-14 cm/min welding speed, 125 A main current, 100 A pulse current, 2.84 Hz oscillation frequency, and 5 Hz pulse frequency-appropriate dissimilar joints, without imperfections, were achieved.

Design, Synthesis, and Preliminary Evaluation for Ti-Mo-Zr-Ta-Si Alloys for Potential Implant Applications

Considering the future trends of biomaterials, current studies are focused on the corrosion resistance and the mechanical properties of new materials that need to be considered in the process of strengthening alloys with additive non-toxic elements. Many kinds of titanium alloys with different biocompatible elements (Mo, Si, Zr, etc.,) have been recently developed for their similar properties with human bone. Four new different alloys were obtained and investigated regarding their microstructure, mechanical, chemical, and biological behavior (in vitro and in vivo evaluation), the alloys are as follows: Ti15Mo7Zr15Ta, Ti15Mo7Zr15Ta0.5Si, Ti15Mo7Zr15Ta0.75Si, and Ti15Mo7Zr15Ta1Si. There were changes with the addition of the silicon element such as the hardness and the modulus of elasticity increased. An MTT assay confirmed the in vitro cytocompatibility of the prepared alloys.

Effects of nickel content on the microstructure, microhardness and corrosion behavior of high-entropy AlCoCrFeNix alloys

In this study the effect of three different nickel concentration on the microstructure, hardness and corrosion properties of high entropy alloys (HEAs) from AlCrFeCoNi system as an alternative material for medical instruments fabrication was investigated. The analyzed HEAs were AlCrFeCoNix obtained by vacuum arc remelting from high purity raw materials and having nickel atomic ratio x = 1.0, 1.4 and 1.8. The microscopy examination revealed the dendritic morphology for the reference alloy (AlCrFeCoNi) and that the extent of the interdendritic areas increased with the concentration of nickel while Cr was more segregated in the interdendritic areas than in dendrites. Hardness values decreased as the percentage of nickel increased due to the dissolution of the precipitates in a nickel-rich matrix and consequently the formation of continuous solid solutions. The corrosion properties of the synthesized HEAs were evaluated using a potentiodynamic polarization method. The alloys were immersed in Simulated Body Fluid during one week and the corrosion parameters were recorded. The low corrosion rates, low corrosion currents and high polarization resistance attest the good stability of these HEAs in simulated biological environment indicating their possible use for surgical and dental instruments.

New Ti-Mo-Si materials for bone prosthesis applications

Several newly obtained titanium alloys were characterized in order to evaluate the biocompatibility and their possible application as implants. For improvement of the performances of the TiMo alloys compared to other alloys, silicon was added, targeting good mechanical and technological properties, avoiding the toxic effects for human body. Titanium is very used in medical applications, due to their extremely low toxicity and good chemical stability in different body fluids. Four Ti15MoxSi (where x = 0, 0.5, 0.75, 1.0 wt %), alloys were developed and investigated regarding microstructure, mechanical, chemical and biological behavior (in vitro and in vivo evaluation). By increasing the Si content from 0 to 1% wt., the mechanical properties of the Ti15Mo alloys were significantly improved. By increasing the Si content from 0 to 1% wt., the mechanical properties of the Ti15Mo alloys were significantly improved (about 50%) from 44.50 GPa to 19.81 GPa modulus of elasticity and the hardness values 361.28 to 188.52 HV. The cytocompatibility assessment on human line osteoblasts indicated good cell-material interactions and in vivo tests indicated a successful osseointegration, the surrounding newly bone being formed without any significant inflammatory reaction. Expression of osteopontin in the peri-implant area highlights the presence of osteogenesis and bone mineralization. Metalloproteinase-2 (gelatinase A) and metallopeptidase-9 (gelatinase B) overexpression in osteoblasts, osteoclasts and osteocytes represent the markers of normal bone remodeling. All these results suggest that the TiMoSi alloys are promising materials for orthopedics devices, since mechanical properties and biocompatibility offer conditions for applying them as biomaterial.

Cutting Behavior of Al0.6CoCrFeNi High Entropy Alloy

There is an increased interest in high entropy alloys as a result of the special possibilities of improving the mechanical, physical or chemical characteristics resulting from metallic matrices made of different chemical elements added in equimolar proportions. The next step in developing new alloys is to determine the cutting conditions to optimize manufacturing prescriptions. This article presents a series of tests performed to estimate the machining behavior of the Al_0.6CoCrFeNi high entropy alloy. The effects of temperature during machining, wear effects on the cutting tool, evolution of the hardness on the processed areas, cutting force components and resultant cutting force for high entropy alloy (HEA) in comparison with 304 stainless steel, scrap aspect and machined surface quality were analyzed to have an image of the HEA machinability. In terms of cutting forces, the behavior of the HEA was found to be about 59% better than that of stainless steel. XRD analysis demonstrated that the patterns are very similar for as-cast and machined surfaces. The wear effects that appear on the cutting edge faces for the tool made of rapid steel compared to carbide during HEA machining led to the conclusion that physical vapor deposition (PVD)-coated carbide inserts are suitable for the cutting of HEAs.

Effects of Fe and Mn on Microstructure and Microhardness of Titanium Alloys

Titanium is one of the most appreciated biocompatible materials, as it possesses both good mechanical characteristics but also high corrosion resistance in contact with biological environments. Initially, Ti-6Al-4V trade mark was used for the manufacture of implantable medical devices, being usually selected for making aerospace structures. Over time, it has been found that aluminum and vanadium are not elements with acceptable biocompatibility, metallic ions being found either dissolved or accumulated in certain areas adjacent to the implants. Therefore, the development of titanium alloys dedicated to biomedical applications is still highly required. The effects of chemical elements (Al, Fe and Mn) on the microstructure and microhardness of titanium alloys for medical applications are analyzed in the paper. The experimental alloys were obtained by melting of raw materials in an argon inert atmosphere of the VAR equipment, using high purity metallic elements. Has been developed Ti-base alloys that contain different concentration of 11 to 18 wt. % Al, 2 to 7wt. % Fe and 6 wt. % Mn for highlighting the effects of these elements on the micro-structure and microhardness of titanium alloys. SEM and EDAX analysis revealed the microstructure and microhardness changes occurred by using of alpha stabilizing elements (Al) or beta stabilizers (Fe, Mn).

Low Density Multi-principal Element Alloy from Al-Mg-Ca-Si-B System

The scientific paper presents a numerical modeling of the chemical composition for the optimization of the multicomponent light alloys in the Al-Mg-Ca-Si-B system. The effects of the proportion of each chemical element on the main characteristics of the alloy based on the mixture rule and the correlation between the melting temperature and the modulus of elasticity were analyzed numerically. The model results has reveals that even other factors must be taken into account, i.e. the mechanical characteristics which varied significantly with changing of chemical compositions. A compromise was set, by slightly increasing the density to acquire better mechanical characteristics. The selected chemical composition was then used to obtain the new low density alloy. In current research stage we conclude that the as cast alloy comprises an inhomogeneous solid solution and complex oxides. Further studies are ongoing on the experimental alloy in various states (homogenization annealed and processed by plastic deformation).

Titanium Influence on the Microstructure of FeCrAl Alloys Used for 4R Generation Nuclear Power Plants

4R generation nuclear power plants should work with metallic material of the highest quality, capable to resist in maximum safe conditions for 25-30 years. FeCrAl alloys are capable of such performance, because of the resistance to: oxidation at high temperatures, corrosion, erosion and penetrating radiations in liquid metal environments. In addition, such materials are capable of forming on their surface some oxide layers, textured and self-renewable, with high adhesion to metallic substrates. These properties can be improved by microalloying with metal elements such as Ti, Zr, Y, Hf in amounts of 1 to 3%. These chemical elements have high affinity to oxygen, being able to stabilize the structure of the superficial layer of oxide (alumina) and to increase adhesion to the metallic substrate. The FeCrAl alloys microalloyed with titanium were obtained in a VAR (Vacuum Arc Remelting) equipment in argon atmosphere (99.99% purity). There were obtained three batches microalloyed with 0.5%, 1% and 1.5% titanium, preserving the same Fe-14Cr-5Al metal matrix. In order to determine the chemical composition of the oxide layer and of the sample bulk, the EDAX analysis was performed. Microstructural features were revealed using SEM analysis. The results showed the capacity of the FeCrAl alloy to form oxide layers, with different textures and rich in elements such as Al and Ti. The compositional analysis performed on FeCrAl samples microalloyed with 0.5, 1.0 and 1.5% Ti in the central zone shows a relatively similar composition compared to the technological calculations made, reflecting the homogeneity of the alloy. The microhardness measurements performed on the cross sections of the metallic samples attest values in the range 163-183 HV0.2, falling within the normal range for these materials. These values are influenced by the presence of the alloying elements in the metallic matrix and by the homogeneous arrangement of constituents.

Comparative Study of Heat Treatment Effects Performed with Solar Energy and Electric Furnace on EN 1.4848 Stainless Steel Alloyed with Co, W, Cu and Mo

This paper presents a comparative study of the microstructure characteristics resulted from heat treatments performed with solar energy and with electric resistance furnace of EN 1.4848 steel alloyed with Co-W-Cu-Mo. In order to increase the hardness characteristics, mechanical strength and fatigue, this steel was previously alloyed with 6.15 wt% Co, 1.8 wt% W, 0.3 wt% Cu and 0.2 wt% Mo. The alloying with Co and W aimed at increasing the hardness, while Cu was added to improve the tensile strength and Mo to increase the fatigue strength. The thermal treatment of EN 1.4848 austenitic stainless steel alloyed with Co-W-Cu-Mo consisted in solid solution quenching in liquid, after heating the samples at 1050�C, maintaining the plateau temperature for about 10 min and subsequently cooling in water or oil. The purpose of this treatment was to dissolve the compounds possibly formed during the production of steel, if any, and to form supersaturated solid solutions, stable at low temperatures and in corrosive environments. The microstructural aspects, microhardness, and Differential Scanning Calorimetry (DSC) results were highlighted, in order to emphasize the solid phase transformations, on both heat treatment variants. The microstructure consists of high-alloy austenite, supersaturated with carbon, with small proportions of delta ferrite with interdendritic precipitations and various intermetallic compounds, very stable and without showing phase transformations up to negative temperatures (- 75 C). Comparing the solar quenched samples to the electric-quenched one, regarding to the differential scanning calorimetry (DSC) analysis, showed that independently of the applied cooling process (in water or oil) the phase transformation temperature is lower for the solar-quenched samples compared to the electric-quenched ones.

Chemical Composition Influence on Microhardness, Microstructure and Phase Morphology of AlxCrFeCoNi High Entropy Alloys

The AlCrFeCoNi high entropy alloy exhibits unexpected properties that can be obtained after mixing five different elements, which could not be obtained from any one independent element. The difference to conventional alloys is that these alloys may have, at the same time, both hardness and plasticity, can be used in severe impact applications. In order to study the influence of aluminum content on the microhardness and microstructure of the high entropy alloys AlxCrFeCoNi (x: atomic ratio, x= 0.2 to 2.0) nine types of samples were obtained as mini-sized ingots (50x15x9.5 mm and 40 g weight). The mini-ingots were obtained using arc melt casting process in a vacuum arc remelting device (VAR MRF ABJ 900). The influence of the chemical elements on the microstructure, phases morphology and microhardness of AlxCrFeCoNi system was studied. The results have confirmed that mechanical properties could be greatly adjusted by the chemical composition change. The main element that influences the microhardness of the analyzed system is aluminum, due to the formation of Al-Fe compounds with high hardness. Increasing the aluminum content in the alloy to values greater than 1.8 ... 2 at.% contribute to the increase of hardness and also to the embrittlement thereof. Other elements like Cr, Fe, Co and Ni can contribute to mitigate increasing the hardness of the alloy. The type of phases formed in high entropy alloy are dependent to the aluminum concentration. So, depending on of aluminium content, different phases are obtained, like FCC for low Al content, mixture of FCC and BCC for about 2.5 %Al and BCC for high Al content. The crystallite size depends on the chemical composition and increase with the aluminium content.

A lab-on-chip cell-based biosensor for label-free sensing of water toxicants

This paper presents a lab-on-chip biosensor containing an enclosed fluidic cell culturing well seeded with live cells for rapid screening of toxicants in drinking water. The sensor is based on the innovative placement of the working electrode for the electrical cell-substrate impedance sensing (ECIS) technique as the top electrode of a quartz crystal microbalance (QCM) resonator. Cell damage induced by toxic water will cause a decrease in impedance, as well as an increase in the resonant frequency. For water toxicity tests, the biosensor's unique capabilities of performing two complementary measurements simultaneously (impedance and mass-sensing) will increase the accuracy of detection while decreasing the false-positive rate. Bovine aortic endothelial cells (BAECs) were used as toxicity sensing cells. The effects of the toxicants, ammonia, nicotine and aldicarb, on cells were monitored with both the QCM and the ECIS technique. The lab-on-chip was demonstrated to be sensitive to low concentrations of toxicants. The responses of BAECs to toxic samples occurred during the initial 5 to 20 minutes depending on the type of chemical and concentrations. Testing the multiparameter biosensor with aldicarb also demonstrated the hypothesis that using two different sensors to monitor the same cell monolayer provides cross validation and increases the accuracy of detection. For low concentrations of aldicarb, the variations in impedance measurements are insignificant in comparison with the shifts of resonant frequency monitored using the QCM resonator. A highly linear correlation between signal shifts and chemical concentrations was demonstrated for each toxicant.

High Entropy Alloys Behaviour During Welding

The High Entropy Alloys have been developed in the last two decades by mixing at least four chemical elements in equiatomic or quasi-equiatomic proportions. Due to the large range of structures and outstanding properties, these advanced materials can be used for structural, high-temperature, wear-resistant, corrosion-resistant, oxidation-resistant, and electrical elements. In order to extend the applicability area of High Entropy Alloys and to improve the knowledge in terms of their behaviour, the researchers worldwide have investigated the phenomena generated by the welding process and its effects produced on their properties. The findings have revealed that these special alloys can be recommended to be used both in high and low-temperature applications. This paper presents a review focused on the weldability and behaviour of CoCrFeMnNi, AlCoCrCuFeNi, AlCrFeCoNi, and CoCrFeNi alloys during Friction Stir Welding, Electron Beam Welding, Laser Beam Welding, and Tungsten Inert Gas. Original results related to the weldability and behaviour of new AlCrFeMnNi alloys developed and subjected to Shielded Metal Arc Welding, as a technical solution for performing morpho-functional structures used in the military field, are presented and discussed, too. The experimental results demonstrated that an appropriate selection of joining technique and filler metal, as well as an optimal combination of process parameters led to performing quality joints, free of defects.

Study on the Microstructural Characteristics of Some Metallic Layers Produced Using the Electrochemical Method and Thermal Spraying

The paper presents the comparative analysis of the microstructural particularities and the superficial characteristics (microhardness and wear resistance) of 3 methods of producing composite layers on metallic support. The aim of the research was to study the possibility of replacing the hard chromium plating process by the thermal metallization process, in order to produce layers resistant to wear and corrosion. Samples produced by hard chromium plating (layers deposited by electrolysis), samples loaded by thermal metallization with electric arc and G3Si1 wire, and samples loaded by thermal metallization with oxy-gas flame and detonation (HVOF) using tungsten carbide as filler material were used in this study.Hard chromium plating allows for high wear resistance thin layers to be produced, but the process is cumbersome and polluting. Thermal metallization allows the production of composite layers, of a chemical composition selected according to the operational demands, in much shorter times and at lower costs. In order to ensure a higher adhesion and to reduce the mechanical stresses at the support-hard layer interface, an intermediate layer of nickel was deposited in the case of samples loaded by thermal metallization with wire. In the paper, the microstructures in cross-section were analysed, the chemical compositions were determined on micro-zones related to the diffusion from the support material and the microhardness in the deposited metal and in the thermally affected zones was measured. These studies have shown that composite metallic layers displaying satisfactory mechanical and microstructural characteristics can be produced using alternative methods (thermal metallization) if optimum regime parameters are chosen.

De novo isochromosome 18p in two patients: cytogenetic diagnosis and confirmation by chromosome painting

This report concerns two patients with clinical features typical for tetrasomy 18p syndrome. Chromosomal analysis revealed a male karyotype in both cases, with an additional small metacentric marker chromosome, putatively an i(18p). Fluorescent in situ hybridization with a chromosome 18-specific paint confirmed that the marker chromosome consisted of chromosome 18 material in both cases.

A retrospective CISS hybridization analysis of a case with de novo translocation t(18;22) resulting in an 18p- syndrome

An unbalanced de novo translocation t(18;22) leading to a severely malformed liveborn girl with 18p- syndrome is described. Using the chromosomal in situ suppression (CISS) hybridization technique on 4-year-old G-banded chromosome preparations, it could be demonstrated that the translocation chromosome is composed of the long arm including the centromere of a chromosome 22 and the long arm of a chromosome 18. Consequently, the patient described here has lost the short arm including the centromere of chromosome 18. The possibility of restudying cytogenetically unsolved cases in clinical cytogenetics using older G-banded chromosome preparations with the fluorescence in situ hybridization techniques is pointed out.

A putative gene family in 15q11-13 and 16p11.2: possible implications for Prader-Willi and Angelman syndromes

The genetic defects in Prader-Willi syndrome (PWS) and Angelman syndrome (AS) map to 15q11-13. Using microdissection, we have recently isolated several DNA probes for the critical region. Here we report that microclone MN7 detects multiple loci in 15q11-13 and 16p11.2. Eight yeast artificial chromosome (YAC) clones, two genomic phage clones, and two placenta cDNA clones were isolated to analyze these loci in detail. Two of the YAC clones map to 16p. Six YAC clones and two genomic phage clones contain a total of four or five different MN7 copies, which are spread over a large distance within 15q11-13. One cDNA clone is from chromosome 15 and one is from chromosome 16. The chromosome 15 cDNA detects transcripts of 14 and 8 kilobases in various human tissues. The presence of multiple copies of the MN7 gene family in proximal 15q may conceivably be related to the instability of this region and thus to the etiology of associated disorders.

Homozygous condition for a BrdU-requiring fragile site on chromosome 12

A rare BrdU-sensitive fragile site, designated FRA12C*RQ24.2 has a relatively high frequency in the normal population. It can be demonstrated in a heterozygous and homozygous condition. There is no evidence that a phenotypic abnormality is associated with the expression of this site. A comparison with the fragile site FRA10B*RQ25.2 has revealed common features with FRA12C*RQ24.2.

Familial ring (20) chromosomal mosaicism

Ring (20) chromosomal mosaicism defined by two cell lines (one normal and the other with the ring) has been demonstrated in lymphocyte and fibroblast cultures from three members of a family through two generations. Two carriers of the ring chromosome were affected and showed the typical signs of r(20) syndrome including mental retardation, microcephaly, behavioral disorders, and epilepsy. The epilepsy is characterized by complex partial seizures sometimes evolving secondarily into generalized tonic-clonic seizures and is poorly controlled by or resistant to medical treatment. The mother of the two patients, also a carrier of ring (20) chromosomal mosaicism, was clinically and phenotypically normal and did not exhibit any signs of epilepsy. Lymphocyte and fibroblast cultures from the most severely affected sib, the proband, contained the highest percentage of cells with ring (20) chromosome and revealed the greatest instability of the ring. Though it is assumed that the ring (20) chromosome arose from terminal breakage and reunion in both arms, no loss of genetic material could be documented cytogenetically. Yet the question arises of how ring chromosomal mosaicism can be passed on. One explanation might be that a chromosome 20 predisposed to terminal lesions or breaks is transmitted from the mother to her offspring. Inherited instability of this type might lead to de novo formation of the ring.

A BrdU-requiring fragile site on chromosome 12

A BrdU-requiring fragile site, fra(12)(q24.2), on human chromosome 12 of some individuals is reported. This fragile site is inherited in a Mendelian codominant fashion and does not seem to be associated with any physical or mental abnormality in carriers. It was mostly observed as a chromatid gap: no acentric fragments, triradials or deleted chromosomes were found. The fra(12)(q24.2) was expressed in 34%-48% of metaphases in lymphocyte cultures from carriers when BrdU and FdU were added 6.5 h before harvest, while the expression ranged between 5% and 20% when the cultures were treated with BrdU alone. The fra(12)(q24.2) represents the second BrdU-requiring rare fragile site described on human chromosomes.

Trisomy 22 in a newborn with multiple malformations

A case of complete trisomy 22 in a live-born female child with multiple malformations is reported. The karyotype of the index patient had 46 chromosomes, with one chromosome 22 missing and one supranumerary metacentric chromosome. Different banding methods and in situ hybridization revealed that the extra chromosome consists of the long arms and a part of the short arms of two chromosomes 22. Our report supplies further proof that a fetus with complete trisomy 22 can occasionally survive to term, but the condition is not compatible with life over a long period.

Familial pericentric inversion of chromosome 12

A pericentric inversion in one of the chromosomes 12, found in two families living in the same region, is described. This inversion was detected during routine chromosomal analysis in two separate laboratories. The breakpoints were at 12p112 and 12q13. The inverted segment represented approximately 20% of the length of chromosome 12. Twenty nine descendants of carriers of the inversion were investigated, and the inversion was present in 23 of them. The other six descendants showed a normal karyotype. After correction for sample bias with the single selection scheme, a segregation ratio of 3:1 was estimated, indicating that the inverted chromosome 12 was preferentially transmitted. All the carriers of the inversion were phenotypically normal, without noticeable fertility disturbances.

On the development of a standard two-dimensional polypeptide map of the human X chromosome

Two-dimensional gel electrophoresis analysis of a rodent-human somatic cell hybrid containing the X as the only human chromosome reveals three polypeptides that are absent in the parental cell line. The presence of these spots in human female fibroblasts indicates their human origin. The polypeptides have molecular weights and isoelectric points of 30,000/5.8,37,000/5.4, and 57,000/4.7 and are designated as PFHG 1, PFHG 2, and PFHG 3. Comparison of their molecular characteristics with those of polypeptides assigned to the human X in two other investigations shows that some but not all polypeptides are similar. Factors are discussed that might interfere with the rapid development of a standardized polypeptide map of the human X.