Vincenzo Ierardi - Academia.edu (original) (raw)

Papers by Vincenzo Ierardi

Vacuum, 2015

ABSTRACT A new outgassing rate facility applying the difference method was established at KIT. Th... more ABSTRACT A new outgassing rate facility applying the difference method was established at KIT. This system was validated within the framework of Joint Research Project IND 12 of the European metrology Research programme by several outgassing reference probes. These served as transfer standards for comparison with three other outgassing rate systems available in the project. Two of the probes were newly developed reference devices and exhibit a known, constant outgassing rate of water. Further two probes were also newly developed outgassing reference devices which emit mixtures of gases. Additionally another probe was an elastomer which was loaded with a known gas mixture. The last probe was a commercially available plastic material whose outgassing shows a large spectrum of gases. The other outgassing rate facilities applied the in-situ calibration of quadrupole mass spectrometers by a primary method, the continuous expansion method (Physikalisch-Technische Bundesanstalt) and the known gas quantity method (Institute of Metals and Technology) or the throughput method (VACOM company).

Journal of Physics: Conference Series, 2013

The polymeric membranes technology is a dynamic growing field, exploited in several areas of appl... more The polymeric membranes technology is a dynamic growing field, exploited in several areas of application like gas separation,[1] sensors, and vacuum technology.[2]It is based on well-known selective permeation process of gas through a polymer, whose selectivity for two different gas is the ratio of their permeability coefficients P. In the last years have been developed methods to fabricate ultra-thin membrane,[3] but there’s no estimation of P. Moreover, even if for thick membrane there is some results, the dependence of P from the thickness is generally poorly investigated. Here we present a novel method to fabricate stable and resistant ultra thin PDMS membranes, and we show their gas permeation characteristics as function of the membrane thickness and the type of gas: CO2 and He. The membranes have been fabricated by spin coating with thickness in the range between few micron and 500 nm. Afterwards, in order to guarantee the necessary mechanical stability, they have been transfe...

Journal of Thermal Analysis and Calorimetry, 2015

ABSTRACT Pristine halloysite nanotubes (HNTs) were studied by thermogravimetry (TG) up to 800 °C.... more ABSTRACT Pristine halloysite nanotubes (HNTs) were studied by thermogravimetry (TG) up to 800 °C. Etching of alumina from inside the tube (causing a significant increase in tube lumen) was realized by treating the material with an acidic H2SO4 solution at 50 °C. Both materials were characterized by TG-FTIR techniques and their thermal behaviors were compared with that of kaolinite. The coupling of TG with FTIR enables to detect the gases evolved during the TG experiments, thus confirming that only pristine HNTs undergo dehydration with the loss of interlayer water molecules at around 245 °C, while dehydroxylation occurs in all these materials in close temperature ranges around 500 °C. TG runs at five different heating rates (2, 5, 10, 15 and 20 °C min−1), was carried out in the same experimental conditions used for the thermal analysis study with the aim to investigate dehydration and dehydroxylation kinetics using some isoconversional methods recommended by the ICTAC kinetic committee, and thermogravimetric data under a modulated rising temperature program. Finally, the results of the kinetic analysis were discussed and explained in terms of the strengths of the hydrogen bonds broken during these processes.

Aim of the project is the generation of nanosensing devices for the simultaneous detection of a r... more Aim of the project is the generation of nanosensing devices for the simultaneous detection of a recently discovered class of cancer biomarkers, endowed with a built-in signal amplification property with unique and extraordinary applicability for biochip fabrication. In particular, the research by our group will be focused on the design, synthesis, and characterization of new compounds that can bind covalently biomolecules and inorganic substrates. The binding capacity and suitability of the prepared materials for microprinting will be tested by AFM analysis.

Materials Research Express, 2014

The most diffused leaks are permeation leak that, despite several disadvantages, above all a stro... more The most diffused leaks are permeation leak that, despite several disadvantages, above all a strong temperature dependence, continue to be preferred in comparison with physical leaks (orifices or capillary). The reasons are connected to the following drawbacks of the physical leaks:

ABSTRACT AbstrAct Aims: sensitivity, selectivity and tunability are keywords to develop effective... more ABSTRACT AbstrAct Aims: sensitivity, selectivity and tunability are keywords to develop effective and reliable diagnostic and bioanalytical tools. In this context, micro and nanofluidic devices constitute a powerful and versatile answer to the growing and urgent demand for innovative solutions. Nevertheless, a precise control of size and functionality of such structures is necessary for ensuring advanced manipulation and sensing capabilities, up to single molecule level. Methods: We report here on different strategies for the development of micro and nanofluidic platforms for advanced diagnostics based on the exploitation of the elastic properties of deformable materials, and on surface chemical functionalization processes. results: We demonstrated that applying a macroscopic mechanical compression to elastomeric nanostructures it is possible to increase their confining power and vary the dynamics of DNA translocation process, while the use of the chemical functionalization allows

Current Physical Chemistry, 2013

Super Paramagnetic Iron-Oxide Nanoparticles (SPION) are currently used as magnetic resonance imag... more Super Paramagnetic Iron-Oxide Nanoparticles (SPION) are currently used as magnetic resonance imaging (MRI) contrast agents. The functionalization of their surface with organic and biocompatible molecules has the purpose to produce carriers selective for different tissues and organs. In this paper, we present the preparation of new cystine-coated ultra small super paramagnetic iron-oxide nanoparticles (USPION) of different core size, from 4 nm to 11 nm. The physical-chemical characterization of these nanoparticles was performed by using several experimental techniques, such as atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM) and magnetic measurements. 1 H NMR relaxation times at different magnetic field strengths have been measured for several waterdispersions of cystine-coated iron-oxide nanoparticles of the smallest dimensions (4 nm). These preliminary results confirm their potentialities as molecular imaging probes and MRI contrast agents.

NanoScience and Technology, 2012

ABSTRACT The knowledge of the effects of single-nucleotide polymorphisms (SNPs) in the human geno... more ABSTRACT The knowledge of the effects of single-nucleotide polymorphisms (SNPs) in the human genome greatly contributes to better comprehension of the relation between genetic factors and diseases. Sequence analysis of genomic DNA in different individuals reveals positions where variations that involve individual base substitutions can occur. Single-nucleotide polymorphisms are highly abundant and can have different consequences at phenotypic level. Several attempts were made to apply atomic force microscopy (AFM) to detect and map SNP sites in DNA strands. The most promising approach is the study of DNA mutations producing heteroduplex DNA strands and identifying the mismatches by means of a protein that labels the mismatches. MutS is a protein that is part of a well-known complex of mismatch repair, which initiates the process of repairing when the MutS binds to the mismatched DNA filament. The position of MutS on the DNA filament can be easily recorded by means of AFM imaging.

Measurement, 2014

Short tubes with diameters of the order of 200 nm were drilled into silicon nitride (Si 3 N 4 ) m... more Short tubes with diameters of the order of 200 nm were drilled into silicon nitride (Si 3 N 4 ) membranes of 200 nm thickness by focused ion beam technology and examined as leak elements for vacuum technology applications. These nano-holes exhibit molecular flow in the pressure range from high vacuum up to 10 kPa and can therefore be used as predictable leak elements for any non-condensable gas species. The geometrical dimensions were determined by SEM, STEM and AFM techniques. By Direct Simulation Monte Carlo method the conductances of these short tubes were calculated from the measured dimensions. The calculated conductance agreed with the value measured by comparison with a primary gas flowmeter within their respective uncertainties. *Corresponding author e-mail address: vincenzo.ierardi@unige.it KEYWORDS: focused ion beam, nanotechnology, Si 3 N 4 , SEM, STEM, AFM, standard leak, gas flow meter, leak rate measurement, vacuum metrology, DSMC.

Nanotechnology, 2009

Nanoindentation experiments carried out with atomic force microscopes (AFMs) open the way to unde... more Nanoindentation experiments carried out with atomic force microscopes (AFMs) open the way to understand size-related mechanical effects that are not present at the macro-or micro-scale. Several issues, currently the subject of a wide and open debate, must be carefully considered in order to measure quantities and retrieve trends genuinely associated with the material behaviour. The shape of the nanoindenter (the AFM tip) is crucial for a correct data analysis; we have recently developed a simple geometrical model to properly describe the tip effect in the nanoindentation process. Here, we demonstrate that this model is valid in indentation of both soft and hard, or relatively hard, materials carried out by two distinct, commercially available, AFM probes. Moreover, we implement the model with a data interpretation approach aimed at preventing underestimation of the tip penetration into the material. Experiments on soft polymeric materials (poly(methyl methacrylate) and polystyrene) and hard or relatively hard (Si, Au, Al) materials are reported. The results demonstrate that true hardness data can be attained also in shallow indentations and that the appearance of size effects strongly depends on

Microscopy Research and Technique, 2008

Atomic force microscopy (AFM) has been applied for determining the topological and structural fea... more Atomic force microscopy (AFM) has been applied for determining the topological and structural features of rabbit spermatozoa. Fresh ejaculated spermatozoa were adsorbed passively onto a silicon slide or by motility from suspension onto a poly(L-lysine)-coated glass coverslip and then imaged in air and in buffer saline, respectively. AFM images clearly highlighted many details of spermatozoa head, neck, and tail. Distinct features were observed in the plasmatic membrane of spermatozoa. In particular, head topography easily recognized the acrosome, equatorial segment, equatorial subsegment, and postacrosome regions. Moreover, AFM images revealed the presence of double belt of invaginations around the spermatozoa head, at the boundary between equatorial subsegment and postacrosome regions. All together, the collected AFM images clearly defined a detailed map of spermatozoa morphology while giving some hints on the internal structure. Microsc. Res. Tech. 71:529-535, in Wiley InterScience (www.interscience.wiley.com).

Journal of Physics: Conference Series, 2013

In order to calibrate leak-detection instruments, devices based on permeation leaks and physical ... more In order to calibrate leak-detection instruments, devices based on permeation leaks and physical leaks are used. Unfortunately, permeation leaks are very sensitive to small temperature fluctuations and can be used only with those gases for which permeating materials are available. While, physical-leaks that overcome these restrictions are susceptible to clog, in particular when the gas flow through them is in viscous regime. Furthermore, for many type of leak devices, the conductance is not predictable based on dimensional, gas species and temperature data, for this reason no estimates or only rough estimates of leak rates are possible for conditions under use where they differ from those of the calibration. Here, we present the fabrication and characterization of a new kind of physical-leak devices based on nano-holes, which overcome these problems. Nano-holes, with diameters less than or equal to 200 nm, work in molecular-flow regime up to atmospheric pressure and for this reason they do not clog. The nano-holes are manufactured by milling a silicon nitride membrane by means of Focused Ion Beam (FIB), and their shapes are characterized by both Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Because of the capability of the AFM to acquire surface three-dimensional images with very high resolution, it is a very useful tool to perform a topographic characterization of the nano-holes.

Journal of Nanoscience and Nanotechnology, 2008

Investigation of the mechanical properties of materials at the nanoscale is often performed by at... more Investigation of the mechanical properties of materials at the nanoscale is often performed by atomic force microscopy nanoindentation. However, substrates with large surface roughness and heterogeneity demand careful data analysis. This requirement is even more stringent when surface indentations with a typical depth of a few nanometers are produced to test material hardness. Accordingly, we developed a geometrical model of the nanoindenter, which was first validated by measurements on a reference gold sample. Then we used this technique to investigate the mechanical properties of a coating layer made of Balinit C, a commercially available alloy with superior anti-wear features deposited on steel. The reported results support the feasibility of reliable hardness measurements with truly nanosized indents.

Vacuum, 2015

ABSTRACT A new outgassing rate facility applying the difference method was established at KIT. Th... more ABSTRACT A new outgassing rate facility applying the difference method was established at KIT. This system was validated within the framework of Joint Research Project IND 12 of the European metrology Research programme by several outgassing reference probes. These served as transfer standards for comparison with three other outgassing rate systems available in the project. Two of the probes were newly developed reference devices and exhibit a known, constant outgassing rate of water. Further two probes were also newly developed outgassing reference devices which emit mixtures of gases. Additionally another probe was an elastomer which was loaded with a known gas mixture. The last probe was a commercially available plastic material whose outgassing shows a large spectrum of gases. The other outgassing rate facilities applied the in-situ calibration of quadrupole mass spectrometers by a primary method, the continuous expansion method (Physikalisch-Technische Bundesanstalt) and the known gas quantity method (Institute of Metals and Technology) or the throughput method (VACOM company).

Journal of Physics: Conference Series, 2013

The polymeric membranes technology is a dynamic growing field, exploited in several areas of appl... more The polymeric membranes technology is a dynamic growing field, exploited in several areas of application like gas separation,[1] sensors, and vacuum technology.[2]It is based on well-known selective permeation process of gas through a polymer, whose selectivity for two different gas is the ratio of their permeability coefficients P. In the last years have been developed methods to fabricate ultra-thin membrane,[3] but there’s no estimation of P. Moreover, even if for thick membrane there is some results, the dependence of P from the thickness is generally poorly investigated. Here we present a novel method to fabricate stable and resistant ultra thin PDMS membranes, and we show their gas permeation characteristics as function of the membrane thickness and the type of gas: CO2 and He. The membranes have been fabricated by spin coating with thickness in the range between few micron and 500 nm. Afterwards, in order to guarantee the necessary mechanical stability, they have been transfe...

Journal of Thermal Analysis and Calorimetry, 2015

ABSTRACT Pristine halloysite nanotubes (HNTs) were studied by thermogravimetry (TG) up to 800 °C.... more ABSTRACT Pristine halloysite nanotubes (HNTs) were studied by thermogravimetry (TG) up to 800 °C. Etching of alumina from inside the tube (causing a significant increase in tube lumen) was realized by treating the material with an acidic H2SO4 solution at 50 °C. Both materials were characterized by TG-FTIR techniques and their thermal behaviors were compared with that of kaolinite. The coupling of TG with FTIR enables to detect the gases evolved during the TG experiments, thus confirming that only pristine HNTs undergo dehydration with the loss of interlayer water molecules at around 245 °C, while dehydroxylation occurs in all these materials in close temperature ranges around 500 °C. TG runs at five different heating rates (2, 5, 10, 15 and 20 °C min−1), was carried out in the same experimental conditions used for the thermal analysis study with the aim to investigate dehydration and dehydroxylation kinetics using some isoconversional methods recommended by the ICTAC kinetic committee, and thermogravimetric data under a modulated rising temperature program. Finally, the results of the kinetic analysis were discussed and explained in terms of the strengths of the hydrogen bonds broken during these processes.

Aim of the project is the generation of nanosensing devices for the simultaneous detection of a r... more Aim of the project is the generation of nanosensing devices for the simultaneous detection of a recently discovered class of cancer biomarkers, endowed with a built-in signal amplification property with unique and extraordinary applicability for biochip fabrication. In particular, the research by our group will be focused on the design, synthesis, and characterization of new compounds that can bind covalently biomolecules and inorganic substrates. The binding capacity and suitability of the prepared materials for microprinting will be tested by AFM analysis.

Materials Research Express, 2014

The most diffused leaks are permeation leak that, despite several disadvantages, above all a stro... more The most diffused leaks are permeation leak that, despite several disadvantages, above all a strong temperature dependence, continue to be preferred in comparison with physical leaks (orifices or capillary). The reasons are connected to the following drawbacks of the physical leaks:

ABSTRACT AbstrAct Aims: sensitivity, selectivity and tunability are keywords to develop effective... more ABSTRACT AbstrAct Aims: sensitivity, selectivity and tunability are keywords to develop effective and reliable diagnostic and bioanalytical tools. In this context, micro and nanofluidic devices constitute a powerful and versatile answer to the growing and urgent demand for innovative solutions. Nevertheless, a precise control of size and functionality of such structures is necessary for ensuring advanced manipulation and sensing capabilities, up to single molecule level. Methods: We report here on different strategies for the development of micro and nanofluidic platforms for advanced diagnostics based on the exploitation of the elastic properties of deformable materials, and on surface chemical functionalization processes. results: We demonstrated that applying a macroscopic mechanical compression to elastomeric nanostructures it is possible to increase their confining power and vary the dynamics of DNA translocation process, while the use of the chemical functionalization allows

Current Physical Chemistry, 2013

Super Paramagnetic Iron-Oxide Nanoparticles (SPION) are currently used as magnetic resonance imag... more Super Paramagnetic Iron-Oxide Nanoparticles (SPION) are currently used as magnetic resonance imaging (MRI) contrast agents. The functionalization of their surface with organic and biocompatible molecules has the purpose to produce carriers selective for different tissues and organs. In this paper, we present the preparation of new cystine-coated ultra small super paramagnetic iron-oxide nanoparticles (USPION) of different core size, from 4 nm to 11 nm. The physical-chemical characterization of these nanoparticles was performed by using several experimental techniques, such as atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM) and magnetic measurements. 1 H NMR relaxation times at different magnetic field strengths have been measured for several waterdispersions of cystine-coated iron-oxide nanoparticles of the smallest dimensions (4 nm). These preliminary results confirm their potentialities as molecular imaging probes and MRI contrast agents.

NanoScience and Technology, 2012

ABSTRACT The knowledge of the effects of single-nucleotide polymorphisms (SNPs) in the human geno... more ABSTRACT The knowledge of the effects of single-nucleotide polymorphisms (SNPs) in the human genome greatly contributes to better comprehension of the relation between genetic factors and diseases. Sequence analysis of genomic DNA in different individuals reveals positions where variations that involve individual base substitutions can occur. Single-nucleotide polymorphisms are highly abundant and can have different consequences at phenotypic level. Several attempts were made to apply atomic force microscopy (AFM) to detect and map SNP sites in DNA strands. The most promising approach is the study of DNA mutations producing heteroduplex DNA strands and identifying the mismatches by means of a protein that labels the mismatches. MutS is a protein that is part of a well-known complex of mismatch repair, which initiates the process of repairing when the MutS binds to the mismatched DNA filament. The position of MutS on the DNA filament can be easily recorded by means of AFM imaging.

Measurement, 2014

Short tubes with diameters of the order of 200 nm were drilled into silicon nitride (Si 3 N 4 ) m... more Short tubes with diameters of the order of 200 nm were drilled into silicon nitride (Si 3 N 4 ) membranes of 200 nm thickness by focused ion beam technology and examined as leak elements for vacuum technology applications. These nano-holes exhibit molecular flow in the pressure range from high vacuum up to 10 kPa and can therefore be used as predictable leak elements for any non-condensable gas species. The geometrical dimensions were determined by SEM, STEM and AFM techniques. By Direct Simulation Monte Carlo method the conductances of these short tubes were calculated from the measured dimensions. The calculated conductance agreed with the value measured by comparison with a primary gas flowmeter within their respective uncertainties. *Corresponding author e-mail address: vincenzo.ierardi@unige.it KEYWORDS: focused ion beam, nanotechnology, Si 3 N 4 , SEM, STEM, AFM, standard leak, gas flow meter, leak rate measurement, vacuum metrology, DSMC.

Nanotechnology, 2009

Nanoindentation experiments carried out with atomic force microscopes (AFMs) open the way to unde... more Nanoindentation experiments carried out with atomic force microscopes (AFMs) open the way to understand size-related mechanical effects that are not present at the macro-or micro-scale. Several issues, currently the subject of a wide and open debate, must be carefully considered in order to measure quantities and retrieve trends genuinely associated with the material behaviour. The shape of the nanoindenter (the AFM tip) is crucial for a correct data analysis; we have recently developed a simple geometrical model to properly describe the tip effect in the nanoindentation process. Here, we demonstrate that this model is valid in indentation of both soft and hard, or relatively hard, materials carried out by two distinct, commercially available, AFM probes. Moreover, we implement the model with a data interpretation approach aimed at preventing underestimation of the tip penetration into the material. Experiments on soft polymeric materials (poly(methyl methacrylate) and polystyrene) and hard or relatively hard (Si, Au, Al) materials are reported. The results demonstrate that true hardness data can be attained also in shallow indentations and that the appearance of size effects strongly depends on

Microscopy Research and Technique, 2008

Atomic force microscopy (AFM) has been applied for determining the topological and structural fea... more Atomic force microscopy (AFM) has been applied for determining the topological and structural features of rabbit spermatozoa. Fresh ejaculated spermatozoa were adsorbed passively onto a silicon slide or by motility from suspension onto a poly(L-lysine)-coated glass coverslip and then imaged in air and in buffer saline, respectively. AFM images clearly highlighted many details of spermatozoa head, neck, and tail. Distinct features were observed in the plasmatic membrane of spermatozoa. In particular, head topography easily recognized the acrosome, equatorial segment, equatorial subsegment, and postacrosome regions. Moreover, AFM images revealed the presence of double belt of invaginations around the spermatozoa head, at the boundary between equatorial subsegment and postacrosome regions. All together, the collected AFM images clearly defined a detailed map of spermatozoa morphology while giving some hints on the internal structure. Microsc. Res. Tech. 71:529-535, in Wiley InterScience (www.interscience.wiley.com).

Journal of Physics: Conference Series, 2013

In order to calibrate leak-detection instruments, devices based on permeation leaks and physical ... more In order to calibrate leak-detection instruments, devices based on permeation leaks and physical leaks are used. Unfortunately, permeation leaks are very sensitive to small temperature fluctuations and can be used only with those gases for which permeating materials are available. While, physical-leaks that overcome these restrictions are susceptible to clog, in particular when the gas flow through them is in viscous regime. Furthermore, for many type of leak devices, the conductance is not predictable based on dimensional, gas species and temperature data, for this reason no estimates or only rough estimates of leak rates are possible for conditions under use where they differ from those of the calibration. Here, we present the fabrication and characterization of a new kind of physical-leak devices based on nano-holes, which overcome these problems. Nano-holes, with diameters less than or equal to 200 nm, work in molecular-flow regime up to atmospheric pressure and for this reason they do not clog. The nano-holes are manufactured by milling a silicon nitride membrane by means of Focused Ion Beam (FIB), and their shapes are characterized by both Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Because of the capability of the AFM to acquire surface three-dimensional images with very high resolution, it is a very useful tool to perform a topographic characterization of the nano-holes.

Journal of Nanoscience and Nanotechnology, 2008

Investigation of the mechanical properties of materials at the nanoscale is often performed by at... more Investigation of the mechanical properties of materials at the nanoscale is often performed by atomic force microscopy nanoindentation. However, substrates with large surface roughness and heterogeneity demand careful data analysis. This requirement is even more stringent when surface indentations with a typical depth of a few nanometers are produced to test material hardness. Accordingly, we developed a geometrical model of the nanoindenter, which was first validated by measurements on a reference gold sample. Then we used this technique to investigate the mechanical properties of a coating layer made of Balinit C, a commercially available alloy with superior anti-wear features deposited on steel. The reported results support the feasibility of reliable hardness measurements with truly nanosized indents.