Purpose
HER2-low breast cancer (BC) is a novel entity with relevant therapeutic implications, especially in hormone receptor (HR) positive BC. This study examines whether HER2 mRNA through the ...21-gene assay, Oncotype DX (ODX), can refine the diagnosis of HER2-low and HER2-
zero
, obtained by immunohistochemistry (IHC).
Methods
Between Jan 2021 and Jan 2023, 229 consecutive HR-positive HER2-negative early BC (T1-3 N0-1) have been characterised by IHC and ODX. HER2 status by IHC was either zero (IHC-0) or low (IHC-1 + and IHC-2 + /ISH-negative) while HER2-zero was further divided into HER2-null (IHC-0) and HER2-ultralow (IHC-1–10%). HER2 gene expression by ODX was negative if lower 10.7.
Results
The distribution of HER2 IHC was as follows: 53.3% HER2-0, 29.25% HER2-1 + , and 17.5% HER2-2 + . The clinicopathological characteristics were similar in the three groups, with higher PgR-negative rate in HER2-zero (13.9% vs 3% vs 5%). The distribution of RS was homogeneous in the three groups with the median HER2 gene expression of 9.20 IQR: 8.70–9.60. HER2 gene expression gradually increased as the IHC score, with substantial overlap. After adjusting for confounders, HER2-1 + and HER2 2 + had a significant positive correlation between HER2 gene expression and IHC OR 1.42, 95% CI 1.21 to 1.68,
p
< 0.001; OR 1.96, 95% CI 1.61 to 2.37,
p
< 0.001 compared to the HER2-
zero
group. HER2 gene expression did not differ between HER2-null and HER2-ultralow subgroups.
Conclusion
Due to the substantial overlap, the HER2 gene expression is unable to properly distinguish HER2-low and HER2-
zero
IHC whose accurate identification is critical in the context of HER2-negative BC.
Cryogenic treatments represent an innovative technology developed with the aim of improving the performance of metallic alloys. The beneficial effects on steels are well documented in the literature, ...whereas their influence on other materials, such as aluminum alloys, is still not completely clarified. Even if the scientific literature reports conflicting data and conclusions, the industrial applications of such treatments are constantly growing. In the present experimental work, the mechanical and corrosion properties of a high-performance 7050 aluminum alloy plate were studied after cryogenic treatment at − 196 °C in liquid nitrogen. Tensile tests were performed on heat-treated samples, and intergranular corrosion tests were carried out on prismatic samples, according to ASTM G110-92 standard. The specimens were exposed to the corrosive environment and the effect of intergranular corrosion was measured by quantitative analysis using light-optical microscopy (LOM). Whereas trifling variation was observed in the mechanical resistance and plastic behavior, the corrosion tests showed a benefic effect of the cryogenic treatment. The microstructure was investigated by FEG-SEM analysis, revealing a different distribution of precipitates near the grain boundaries, which was able to reduce the electrochemical potential difference among these regions and the center-grain.
Sigma phase precipitation occurring during the exposure of duplex stainless steels in the temperature range from 800 to 900 °C deeply affects the material toughness and corrosion resistance. σ-Phase ...precipitation process is strongly influenced by many physical parameters, such as the specific chemical composition, the ferrite amount and its average grain size, and the entity of plastic deformation due to the previous technological process. The strong dependencies of σ-phase precipitation on all these factors justify the continuous study of the process kinetics. This paper focuses on the σ-phase precipitation kinetics in F55 steel grade. The investigation has been performed by an innovative experimental method, such as the anisothermal dilatometric technique. The application of the Kissinger’s method has been used for deriving the process activation energy and kinetics. The results have been compared with the ones obtained by metallographic analysis and hardness tests performed on isothermally aged samples, heat-treated in a laboratory furnace at 850 °C.
In this work, fire simulations were carried out on zinc-coated steel sheets usually employed for the structural parts of furniture, transformer rooms and aeration pipes. The thermal alteration ...induced by the fire was simulated by heating samples at 13 different temperatures (from 20° C to 1050° C) and for different exposure times (1 h and 6 h) in a laboratory furnace. The metallurgical investigation concerned the surface coloring by photographic analysis, the morphology and chemical composition of the surface oxides by SEM and EDS and the microstructure modifications as a function of the temperature by LOM. The influence of the different parameters was discussed by a statistical approach. The obtained results allowed to associate the temperature to one or more alteration of the steel microstructure and of the color, the morphology and the chemical composition of the surface oxides.
The standard ISO 1.2738 medium-carbon low-alloy steel has long been used to fabricate plastic molds for injection molding of large automotive components, such as bumpers and dashboards. These molds ...are usually machined from large pre-hardened steel blooms. Due to the bloom size, the heat treatment yields mixed microstructures, continuously varying from surface to core. Negative events (such as microcracks due to improper weld bed deposition or incomplete extraction of already formed plastic objects) or too large thermal/mechanical stresses can conceivably cause mold failure during service due to the low fracture toughness and fatigue resistance typically encountered in large slack quenched and tempered ISO 1.2738 steel blooms. Alternative steel grades, including both non-standard microalloyed steels, designed for the same production process, and precipitation hardening steels, have recently been proposed by steelworks. However, the fracture toughness and the fatigue properties of these steels, and hence their response during the service, are not well known. Results of an experimental campaign to assess the fracture toughness and fatigue properties, as well as the basic mechanical properties, of a microalloyed and a precipitation hardening plastic mold steel blooms are presented and commented, also in respect to the results previously obtained by two commercial ISO 1.2738 ones. Experimental results show that these steels generally exhibit low fracture toughness values; in the traditional quenched and tempered bloom steels the brittleness may be caused both by the presence of mixed microstructures and by grain boundaries segregation, while in the precipitation hardened one the brittleness probably stems from the precipitation phenomena. This study suggests that microalloyed and precipitation hardening steels may be used to produce large plastic mold, yet the fracture toughness still remains the most critical property.
For the past many years, 7075 aluminum alloys have been widely used especially in those applications for which high mechanical performances are required. It is well known that the alloy in the T6 ...condition is characterized by the highest ultimate and yield strengths, but, at the same time, by poor stress corrosion cracking (SCC) resistance. For this reason, in the aeronautic applications, new heat treatments have been introduced to produce T7X conditions, which are characterized by lower mechanical strength, but very good SCC behavior, when compared with the T6 condition. The aim of this study is to study the tensile properties and the SCC behavior of 7075 thick plates when submitted to a single-step aging by varying the aging times. The tests were carried out according to the standards and the data obtained from the SCC tests were analyzed quantitatively using an image analysis software. The results show that, when compared with the T7X conditions, the single-step aging performed in the laboratory can produce acceptable tensile and SCC properties.
Powder metallurgy (PM) processing of steels typically results in a material characterized by residual porosity reducing the mechanical strength of the material. That is why mechanical components ...produced from PM steels for high demanding applications often require a surface hardening in order to improve both the fatigue and the wear resistance. Among the surface treatments, gas nitriding assures economic advantages but the presence of interconnected porosity also makes the core structure involved by the diffusional phenomena. In this paper gas nitriding is proposed in combination with shot peening, as a surface densification technique, to improve the wear performances of PM components from prealloyed powder. 40mm diameter, 9.85mm thickness disks were pressed at 7.0g/cm3 density from a pre-alloyed powder (1.5% Cr, 0.5% Mo), with 0.8% graphite. The disks were sintered at 1120°C, 30min, in N2–H2 (90–10) atmosphere in an industrial equipment. Four conditions of the disks were examined: as-sintered, sintered and gas nitrided, sintered and shot-peened, sintered-shot peened-gas nitrided. The disks were characterized by experimental tests: dimensional variations, macro and microhardness profiles, LOM observations, surface texture analysis, residual stress analysis by X-Ray technique and pin on disk wear tests. The results of the wear tests were fulfilled with observations by SEM and new interesting interpretations of the involved mechanisms were proposed by the application of the energetic approach and non-standard wear tests.
► Gas nitriding and a pre-nitriding densification by shot-peening on a Cr based sintered steel are carried out. ► The effects on the microstructural characteristics and the wear resistance have been studied. ► Non standard wear tests have been performed. ► Energetic approaches have been introduced in the discussion of the results.
The kinetics of the precipitation of copper-rich phase in 17-4 PH stainless steel was studied in this paper by non-isothermal dilatometric experiments. The dilatometric curve was analyzed and the ...conversion degree of the precipitates was associated with the area under the derivative curve of the thermal expansion as a function of temperature. The apparent activation energy associated with the formation of the precipitates was calculated and the obtained results were compared with the data calculated from the isothermal dilatometric tests presented in a previous paper. The data well agree, so confirming that non-isothermal dilatometry can be considered a powerful method to study the precipitation kinetics of PH stainless steels. Finally, the conversion degree for any isothermal treatment was calculated starting from the parameters obtained by non-isothermal dilatometric tests and compared with the conversion degree calculated from the hardness values during heat treatments.
Powder metallurgy processing of steels typically results in materials characterized by residual porosity, whose sizes and morphology, together with the microstructure, strongly affect the fatigue ...crack growth behaviour of the materials.
Prismatic specimens were pressed at 7.0
g/cm
3 density from Astaloy CrM powder and sintered under different conditions, varying the sintering temperature and the cooling rate after sintering.
Optical observations allowed us to evaluate the sizes and the morphology of the porosity and the microstructural characteristics for all the investigated conditions. Fatigue tests were performed at
R-ratio equal to 0.1 to investigate the threshold zone and to calculate the coefficients of the Paris law. All the tests were carried out according to the compliance method, and the crack length was evaluated during the tests. Moreover,
K
IC tests were performed in order to complete the investigation.
On both fatigue and
K
IC samples, a fractographic analysis was carried out to investigate the crack path and the fracture surface features.
The results show that the exponent of the Paris law is about 6.0 for 1120
°C sintered and about 4.7 for 1250
°C sintered materials. Interesting data have been also found for the threshold values.
The elastic and plastic properties of some ferrous base materials, before and after steam treatment, have been evaluated by means of a rather new testing method, named universal hardness testing. ...This test makes it possible to record continuously the instantly applied load and the indentation depth. The plotted curves enable to get indications on elastic and plastic deformation works, on sintering degree and on the Young's modulus as well. The elastic properties have been compared with the results achieved by means of strain gages in four-point bending tests. The influence of oxide layers on the elastic behaviour of steam-treated ferrous materials has been evaluated. The observation of tested areas at optical microscope helps to understand the features of oxide layers and their adhesion to the metallic matrix. The results may be useful to refine the design choice of powder metallurgy materials to be steam treated, in order to fulfil specific requirements of demanding applications, and to rate the correctness of the oxidation process.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
PDF
