Surface chemical analysis of raw cotton fibres and associated materials

The surface chemical composition of raw unscoured cotton was successfully investigated by the surface analytical techniques X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The presence of non-cellulosic material at the fibre surface was established and determined to be a complex mixture of fatty acids, alcohols, alkanes, esters and glycerides. The effect of scouring and bleaching was to reduce the surface concentration of these materials but even after aqueous processing some non-cellulosic material residue was still detected at the fibre surface.     

Evaluation and comparison of layered titanate nanosheets using TOF‐SIMS and g‐ogram analysis

The evaluation of nanostructure is important to develop the highly controlled nanomaterials. In this study, two kinds of layered titanate nanosheets, which were produced by using hexylamine and laurylamine, respectively, as surfactants were investigated by Gentle Secondary Ion Mass Spectrometry Gentle‐SIMS (G‐SIMS) and g‐ogram, which is the latest Time‐of‐Flight Secondary Ion Mass Spectrometry (TOF‐SIMS) data analysis method for detecting more intact ions and obtaining the information on original chemical structures of samples precisely from complicated TOF‐SIMS spectra. As a result, molecular related ions of the surfactants were detected from each sample, and the structural information of samples was obtained. From both samples, surfactant molecular ions connected with hydrocarbon were detected as more intact ions rather than molecular ions of themselves. It was suggested that hydrophobic domains of their lamellar mesostructure are formed robustly by more than two surfactant molecules connected with each other linearly. After all, important information on the chemical structure of the layered titanate nanosheets, which would be difficult to be found by using typical structural analysis methods such as X‐ray diffraction and transmission electron microscopy, were obtained using G‐SIMS and g‐ogram. Therefore, it was shown that g‐ogram and G‐SIMS are helpful to evaluate the nanostructured materials. And it was also shown that g‐ogram is applicable to organic–inorganic materials which contain long hydrocarbon structures. Copyright © 2015 John Wiley & Sons, Ltd.     

Porous glass as a support for chemically bonded stationary phases for HPLC

Summary Two different types of porous glass (PG) were submitted to a thermal treatment in a temperature range from 620°C–700°C for 2 to 100 h. The materials thereby obtained have been characterized by static Secondary Ion Mass Spectrometry (SIMS). Special attention was paid to the change of the boron surface concentration. In addition we studied the specific surface area (S_BET) dependence on the thermal treatment parameters, such as heating time and heating temperature. Selected PG materials have been modified with organosilanes and characterized prior to their use as packings in RP-HPLC.Dedicated to B. B.'s parents on their 60th birthday     

Characterisation of amino acid modified cellulose surfaces using ToF-SIMS and XPS

Cellulosic fibrous networks are modified using 3 different amino acids; small (Glycine, Gly), aliphatic (Leucine, Leu) and aromatic (Phenylalanine, Phe). The effect of amino acid functionality on chemical coupling to cellulose fibres in terms of their coverage and packing density are investigated. Different amino acid modified cellulose networks are characterised by using Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and X-ray Photoelectron Spectroscopy (XPS). The presence of amino acids is confirmed using ToF-SIMS. The quantitative distribution of different amino acids across the cellulose surface is assessed by using XPS. It is shown that the packing density of amino acids depends on the size of the side chain; smaller amino acids (Gly, Leu) tend to couple to the surface at higher density compared to larger ones (Phe). This study has implications for the functionalisation of polysaccharide materials for a wide range of applications.     

Mechanism of the Anionic Ring-Opening Oligomerization of Propylene Carbonate Initiated by the tert-Butylphenol/KHCO3 System

The ring-opening oligomerization reaction of propylene carbonate in the presence of the tert-butylphenol/KHCO₃ initiating system was studied by means of Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) and Electrospray Ionization Time of Flight Mass Spectrometry (ESI-TOF MS). According to the MS spectra obtained, different series of peaks were identified. The MS spectra clearly showed that besides the chain-extension reaction yielding oligomers with all propylene oxide units, the formation of oligomers containing carbonate linkages in the chain, and condensation reaction between the latter two also took place. The structure of the oligomers carrying carbonate linkages was determined by the post-source decay (PSD) MALDI-TOF MS/MS method. Based on the MS results, a mechanism for the oligomerization reaction is proposed.     

TOF‐SIMS characterization of an aluminovanadate oxide catalyst

Time‐of‐flight Secondary Ion Mass Spectrometry (TOF‐SIMS) has been employed to characterize the surface physical and chemical state of aluminovanadate oxide catalyst precursors (‘V? Al? O’) precipitated at different pH values in the range of 5.5…10. The reference oxide V₂O₅ has also been studied for comparison purposes. It is shown that the analysis of molecular ion emission yields valuable information on the surface elemental and phase composition. Increasing pH values while precipitating from aqueous precursor solutions are found to result in a monotonic variation of the surface composition, in a progressive hydroxylation of aluminium and vanadium and in an increasing dispersion of vanadium oxide species. SIMS data evaluated on the basis of Plog's valence model of molecular ion emission reveal reduced V⁴⁺ states, the fraction of which is dependent on the pH value. The SIMS results are supported by XPS data. The enhancement of the catalytic activity in oxidative propane dehydrogenation over V? Al? O prepared at high precipitation pH is in good correlation with the measured surface characteristics. Copyright © 2007 John Wiley & Sons, Ltd.     

The Surface Modification of Pure Cellulose Paper Induced by Low-Pressure Nitrogen Plasma Treatment

We have used Time of Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) in combination with X-ray photoelectron spectroscopy (XPS) to study chemical changes taking place at the surface of pure cellulose paper samples treated in N₂ plasma for periods of time up to 60 seconds. High resolution TOF-SIMS spectra permit the detection of various functionalities containing nitrogen, even following very brief (2s) plasma exposure. Correlations between chemistry and surface properties, such as water wettability, are presented and discussed.     

Eignung von Tiefenprofilanalysen zur Charakterisierung von Oxidschichten an Hochtemperaturlegierungen

Summary The characterization of oxide scales by their composition and structure is necessary in order to predict their protective behaviour for the high temperature alloys in various corrosive media. For this purpose information obtained by classical methods, such as metallography, X-ray diffraction and microprobe analysis can be supplemented by depth profiles determined by various spectroscopical methods.In this paper, HASTELLOY X und INCONEL 617 were oxidized for relatively short times in two different atmospheres. Depth profiles were determined by GDOS (Glow Discharge Optical Spectroscopy), SNMS (Secondary Neutral Mass Spectrometry) and SIMS (Secondary Ion Mass Spectrometry).The measured profiles were compared with the results of non-destructive X-ray diffraction analysis to characterize the scales and the oxide-metal interface.     

Molecular relaxations in ester‐terminated,amide‐based dendrimers

This study utilized Matrix Assisted Laser Desorption/Ionization Time‐of‐Flight Mass Spectrometry, Thermogravimetric Analysis, Differential Scanning Calorimetry, X‐Ray Diffraction, and Dielectric Analysis to assess the viscoelastic and structural properties of three generations of tert‐butyl and methyl ester, amide‐based dendrimers. The effect of generation number and functionality on glass‐transition temperatures and corresponding apparent activation energies, obtained via adherence to WLF behavior, were determined. Both were found to increase with increasing generation number and bulkiness of terminal functionalities. WLF constants, C₁ and C₂, allowed the determination of free volume, and thermal expansion coefficients, respectively. Secondary transitions, conforming to Arrhenius behavior, were also characterized and increased in temperature with generation number. The apparent activation energy was greater when the matrix was crystalline. Dielectric relaxation responses were analyzed to yield dielectric strengths of the molecular relaxations which increased with generation number and were comparable for both tert‐butyl and methyl esters in the glass‐transition region. Electrical properties of the dendrimers were dominated by ionic conductivity in the high temperature region. In order to unmask the glass transition, the data were treated in terms of the electric modulus. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2025–2038, 1999     

Characterization and reduction of pellicle degradation due to haze formation on leading edge technology photomasks

Since the adoption of deep ultraviolet lithography, time‐dependent haze defects have become an increasingly significant problem for the semiconductor industry as photomask lifetime continues to be shortened due to molecular contamination. With shorter wavelength lithography, the materials and space between the pellicle film and photomask surface can create a highly reactive environment resulting in the formation of haze defects on the photomask. One critical issue has been to understand the chemical mechanism of evolving defects on the photomask triggered by haze formation. This fundamental study was completed in a manufacturing environment in response to a sudden increase of haze defect growth during the transition to new device nodes. Time‐of‐Flight Secondary Ion Mass Spectrometry and Atomic Force Microscopy analysis techniques were essential in characterizing pellicle degradation in parallel with increased haze defect growth on the photomask surface. Extensive chemical and surface topography characterization of pellicle degradation led to a vitally important development and implementation of a design change in the pellicle frame for Flash Memory 3x and 2x nm node critical process layer photolithography. With an increased clearance between the pattern design and pellicle edge, the design modification ultimately brought an immense increase in photomask dose limitation between repell cleans and a reduction in haze growth, thus, reducing production costs and increasing wafer throughput.     

Structural model of CO dissociation on Pd particles

In order to modelize the CO dissociation observed on palladium particles, by means of Static Secondary Ion Mass Spectrometry, theoretical investigations were performed on small Pd clusters by using a local approximation of the density functional theory. Several types of defects were studied concerning their ability to dissociate the CO molecule.     

Phase formation and impurity effects in Ar+ ion irradiated Mo/Si thin film bilayer system

We report a dose‐dependent phase evolution in Mo/Si bilayer system upon Ar⁺ ion beam irradiation and subsequent flash annealing at 800 °C for 60 s. Micro‐structural characterization with Grazing Incidence X‐ray Diffraction and Raman scattering reveals a dose‐dependent nucleation of polymorphic phases occurring at the amorphized interface region. The ion beam mixing process has been investigated by Secondary Ion Mass Spectrometry and Rutherford Backscattering Spectrometry. While low ion doses favour nucleation of only metastable MoSi₂ phase, co‐existence of polymorphic phases are observed at high ion doses. The persistence of such polymorphic phases even after a high‐temperature anneal for high dose implanted specimen is indicative of phase retardation. The phase retardation of h‐MoSi₂ to t‐MoSi₂ is accounted in terms of nucleation and growth process. Copyright © 2012 John Wiley & Sons, Ltd.     

Trace-analytical methods for monitoring contaminations in semiconductor-grade Si manufacturing

Generating systematic data on incoming materials, processes, production environments and products by contamination monitoring and analyis is the key element of quality assurance in semiconductor fabrication. To be able to match the analytical capabilities to the requirements of improving materials and processes, the level of sophistication of contamination monitoring and analysis systems must be higher than the expected demands in the fabrication line. The accuracy of each analytical method has to be cross-checked by different independent techniques. Accuracy, precision, power of detection, analysis time and expenses should always be tailored to the particular case. All monitoring methods must run under statistical process control. The methods described meet the analytical requirements of the near future in semiconductor grade silicon manufacturing.Glossary AAS Atomic Absorption Spectrometry - ADD Acid-mixture Drop Decomposition of the native oxide and, occasionally of Si surface due to given acid etchant mixtures such as HF+HNO₃ in order to preconcentrate dissolvable metallic impurities of the surface (c.f. MAD, VPD, WSSD) - AEM Analytical Electron Microscopy - AEPS Auger Electron Appearance Potential Spectroscopy (=APAES) - AES Auger Electron Spectroscopy - AFM Atomic Force Microscope - AM Acoustic Microscopy - AMS Accelerator Mass Spectrometry (Tandem-SIMS) - APIMS Atmospheric Pressure Ionization Mass Spectroscopy - ARAES Angle-Resolved Auger Electron Spectroscopy - ARUPS Angle-Resolved Ultraviolet Photoemission Spectroscopy - ATR-FTIR Attenuated Total Reflection Fourier Transform Infrared Spectroscopy - BEEM Ballistic Electron Emission Microscopy - BMD heat induced Bulk Micro-Defects in monocrystalline Si after a specified thermal process cycle, corresponding to SIO_x precipitates in monocrystalline Si [31] - BSE Back Scattered Electrons - CE Capillary Electrophoresis (cf. CIA) - CIA Capillary Ion Analysis (cf. CE) - COP Crystal Originated Particle detected as LPD - CV Capacitance-Voltage measurement - CVD Chemical Vapor (phase) Deposit(ion) - CZ-Si monocrystalline Si grown by Czochralski-method from quartz crucible in a noble gas atmosphere - DCT Coulbe Crystal x-ray Topography - DLTS Deep Level Transient Spectroscopy [72] - DRAM Dynamic Random Access Memories operate as memory devices by storing charge near the Si wafer surface in micro-capacitors. Defects and impurities can cause the loss of the stored charge and a periodic refresh of the signals is required (cf. PTF). - DTDA Differential Thermal Desorption Analysis [73] - DZ Denuded Zone, i.e. a subsurface layer free of SiO_x precipitates - EBIC Electron Beam Induced Conductivity - EDS Energy Dispersive Spectroscopy - EDAX Energy Dispersive Analysis of X-rays - EELS Electron Energy Loss Spectroscopy - EG Extrinsic Gettering, i.e. removal of metals from the active device region by dislocation stress in the back side of the wafer - Elymat Electrolytical Metal Tracer [69] - EMP Electron MicroProbe - EPA Electron Probe Analysis - EPMA Electron Probe Micro-Analysis - ERDA Elastic Recoil Detection Analysis - ESCA Electron Spectroscopy for Chemical Analysis (= XPS) - ETV Electro Thermal Vaporization - fab manufacturing process or fabrication line of microchips - FESEM Field Emission Scanning Electron Microscopy - FIB Focused Ion Beam - FIM Field Ion Microscopy - FLAA FlameLess Atomic Absorption - FMEA Failure Mode and Effect Analysis - ()-FTIR (Microspot) Fourier Transform InfraRed Spectroscopy - FTPL Fourier Transform PhotoLuminescence - FZ-Si monocrystalline Si grown by float zone method from a polycrystalline Si rod in an rf-coil - GDMS Glow Discharge Mass Spectrometry - GFA Gas Fusion Analysis (heat extraction of O_i from Si by graphite reduction, [75]) - GF-AAS Graphite Furnace AAS - GLP Good Laboratory Practice (protocol defining general operations) - GMP Good Measurement Practice (protocol defining technique-specific operations) - GOI Gate Oxide Integrity test - Graff test surface precipitation of metallic silicide due to quenching annealed (1100°C) Si wafer, detection by Sirtl etch, cf. TEG haze test [76, 77] - HeD He thermal Desorption spectroscopy - HIBS Heavy Ion Backscattering Spectrometry - HREELS High-Resolution Electron Energy Loss Spectroscopy - HREM High Resolution Electron Microscopy index for interstitials (O_i, Si_i etc.) in monocrystalline Si - IC Ion Chromatography - ICISS Impact-Collision Ion-Scattering Spectroscopy - ICP-OES Inductively Coupled Plasma Optical Emission Spectrometry - ICP-MS Inductively Coupled Plasma Mass Spectrometry - IG Intrinsic Gettering, removal of metallic impurities from the device active region and trap them in the bulk using supersaturated O_i in Si and inducing SiO_x precipitation by thermal annealing - INNA Instrumental Neutron Activation Analysis [70, 71] - IR InfraRed Spectroscopy - IRAS Infrared Reflection Adsorption Spectroscopy - ISS Ion-Scattering Spectroscopy (cf. RBS) - LAMMA Laser (Ablation) Microprobe Mass Analyzer - LANG scanning Lang x-ray topography - LAR-RBS Lateral and Angle Resolved RBS-Imaging [78] - LEED Low Energy Electron Diffraction - LM-PC (non-contact) Laser/Microwave PhotoConductance - LOD Limit Of Detection (2–3 of noise level, [12]) - LOQ Limit Of Quantification (>6 of noise level, Fig. 2/3, [11, 13] - LPD Ligh Point Defect, sites scattering laser beam on monocrystalline Si surface (particles, pits, dimples, scratches, nm-terrasses, etc.) - LST Laser Scattering Topography - LT-FTIR Low Temperature Fourier Transform InfraRed Spectroscopy - LTV Local Thickness Variation - LPI-SNMS Laser Resonance Ionization SNMS - MAD Mixed Acid Droplet (cf. ADD, VPD, WSSD) - MAKYOH magic mirror optical surface reflection method (Jpn.) - Mb megabit, quantum of digital unit of information, number of memory addresses of a microchip, 4 Mb is about the information capacity of 250 pages/DIN A4 - ME Monochromatic Ellipsometry - MOR Modulated Optical Reflectance - MOS MetalOxide Semiconductor (transistor) - NRA Nuclear Reaction Analysis - NRIS NonResonant Ionization Spectroscopy - OF Orientation Flat to position Si wafers due crystal orientation - OM Optical Microscopy (usually differential interference/phase contrast Nomarski microscopy) - MOS-CAP/TAU Metal Oxide Semiconductor Capacitance/generation lifetime test for minority carrier - OSF hermal Oxidation-induced Stacking Fault in monocrystalline Si [31] - -PCD Microwawe reflection Photo Conductive Decay - PAM PhotoAcoustic Microscopy - PAS Positron Annihilation Spectroscopy - PCMS Plasma Chromatography Mass Spectroscopy - PC-SIMS Polyencapsulation Secondary Ion Mass Spectroscopy - PET Puddle Etch Test (HF/HNO₃-dissolution of 10 mm spots on as-sliced, as-lapped, as-etched wafers, [43]) - PFZ Precipitation Free Zone (cf. DZ) - PIXE Particle Induced X-ray Emission - PL PhotoLuminescence - POD Power Of Detection (LOD with real sample matrices, [14]) - 4-PP 4-Point Probe - PSI Phase Shift Interferometry - PSP Protocol for Specific Purposes (defining entire measurement program) - PTF Pause Time Failure can occur between periodic refresh of the stored data (cf. DRAM) - -Raman Raman Microprobe - RBS Rutherford BackScattering (cf. ISS) - RHEED Reflection High Energy Electron Diffraction - RIS Resonant Backscattering Ion Spectroscopy - SALI Surface Analysis by Laser Ionization - SAM Scanning Auger Microprobe/Microscopy - Schimmel etch defect/preferential etching for Si(100) [79] - Secco etch defect/preferential etching for Si(100) [79] - SEM Scanning Electron Microscopy - SERS Surface-Enhanced Raman Spectroscopy - SIMS Secondary Ion Mass Spectroscopy - SIRIS Sputter Initiated Resonant Ionization Spectroscopy - SIRM Scanning InfraRed Microscopy - Sirtl etch defect/preferential etching for Si(111) [79] - SOM-DPC Scanning Opt. Micr. Differential Phase Contrast - SNMS Sputtered Neutral Mass Spectroscopy - SOP Standard Operation Procedure (defining sampling and measurement process) - SPC Statistical Process Control - SPM Scanning Photon Microscope - SPV Surface Photo-Voltage - SRP Spreading Resistance Profiling - SSD Solid State Detector or Device - STM Scanning Tunneling Microscopy - S-ULSI Super-Ultra Scale Integration (Density)=16 Mb - SXES Soft X-ray Emission Spectroscopy - TCS Total Customer Satisfaction, the hotly pursued goal of all vendors of industrial goods - TDS Thermal Desorption Spectroscopy - TDBD Time Dependent Break-Down voltage - TDDB Time Dependent Dielectric Break-down voltage - TPD Temperature-Programmed Desorption - TEG haze test according to Telefunken Electronic Ges (cf. Graff-test) - TEM Transmission Electron Microscopy - TOF-SIMS Time of Flight Secondary Ion Mass Spectroscopy - TQM Total Quality Management - TTV Total Thickness Variation - TXRF Total Reflection X-Ray Fluorescence [80] - TREX Total Reflection Energy Dispersive X-ray fluorescence - ULSI Ultra-Large Scale Integration (Density)=4 Mb - UPS Ultraviolet Photoelectron Spectroscopy - US UltraSonic - VLSI Very Large Scale Integration (Density)=1 Mb - VPD Vapor Phase Decomposition (vapor phase reaction of HF with native Si-oxide and scanning the surface with a UPW or H₂O₂ solution droplet [38, 53], cf. ADD, MAD, WSSD) - Wright etch defect/preferential etching for Si(100) and Si(111) [79] - WSA Wafer Surface Analysis - WSSD Wafer Surface Scanner Device (automated VPD) - XPS X-ray Photoelectron Spectroscopy - XRD X-ray Diffraction - XRF X-ray Fluorescence - XRT X-ray Topography - XTEM X-ray Transmission Electron Microscopy     

The CrOx/SiO2/Si(100) catalyst – a surface science approach to supported olefin polymerization catalysis

Depositing catalytically active particles onto flat, thin and oxidic support forms an attractive way to make supported catalyst suitable for surface science characterization. Here we show how this approach has been applied to the Phillips (CrO_x/SiO₂) ethylene polymerization catalyst. The model catalyst shows a respectable polymerization activity after thermal activation in dry air (calcination). Combining the molecular information from X‐ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS) we can draw a molecular level of the activated catalyst that features exclusively monochromate species, which are anchored to the silica support via ester bonds with the surface silanol groups. These surface chromates form the active polymerization site upon contact with ethylene. Upon increasing calcination temperature we observe a decrease in chromium coverage as some of the surface chromate desorbs from the silica surface. Nevertheless, we also find an increasing polymerization activity of the model catalyst. We attribute this increase in catalytic activity to the isolation of the supported chromium, which prevents dimerization of the coordinatively unsaturated active site. Diluting the amount of chromium to 200 Cr‐atoms/nm² of silica surface enables the visualisation of polyethylene produced by a single active site.     

Profile of Parkia speciosa Hassk Metabolites Extracted with SFE using FTIR‐PCA Method

A rapid identification, classification and discrimination tool, using Fourier Transform Infrared (FTIR) spectroscopy combined with Principal Component Analysis (PCA), was developed and applied to determine the profile of the Supercritical Fluid Extraction (SFE) of Parkia speciosa seeds under various temperature and pressure conditions (313, 323, 333, 343, 353 and 363 K and 20.68, 27.58, 34.47, 41.37, 48.26, and 55.16 MPa). The separation and identification of the compounds was carried out by Gas Chromatography coupled with Time of Flight Mass Spectrometry (GC/TOF‐MS). This technique has made it possible to detect the variability obtained under different SFE conditions and the separation of different chemical compounds in P. speciosa seeds. The FTIR‐PCA results were verified by GC/TOF‐MS, and the FTIR‐PCA method successfully identified the unsaturated carboxylic acids with the highest percentage area under the different conditions.     

Quantitative profiling of SiGe/Si superlattices by time-of-flight secondary ion mass spectrometry: the advantages of the extended Full Spectrum protocol

The abundance of work on SiGe-based devices demonstrates the importance of the compositional characterization of such materials. However, Secondary Ion Mass Spectrometry (SIMS) characterization of SiGe layers often suffers from matrix effects due to the non-linear variation of ionization yields with Ge content. Several solutions have been proposed in order to overcome this problem, each having its own limitations such as a restricted germanium concentration range, or a weak sensitivity to dopants or impurities. Here, we studied the improvements brought by an alternative protocol: the extended Full Spectrum protocol, which states proportionality between the composition of the secondary ion beam and that of the actual material. Previous studies on this protocol showed that it was extremely precise and reproducible for Ge quantification in a permanent regime, because of minimized matrix effects. In this study we thus investigated its accuracy for the simultaneous quantitative depth profiling of both matrix elements (Si, Ge) and impurities (B, C or P) in strained SiGe/Si superlattices by comparing results with those from more classic protocols. The profiles provided by the extended Full Spectrum protocol were found to be accurate, and to exhibit better properties than classic protocols in terms of signal/noise ratio and signal stability, along with a slight enhancement in depth resolution.     

Characterization of the distribution of the sintering activator boron in powder metallurgical steels with SIMS

Powder metallurgy is a well-established method for manufacturing ferrous precision parts. A very important step is sintering, which can be strongly enhanced by the formation of a liquid phase during the sintering process. Boron activates this process by forming such a liquid phase at about 1200 °C. In this work, the sintering of Fe–B was performed under the protective atmospheres of hydrogen, argon or nitrogen. Using different grain sizes of the added ferroboron leads to different formations of pores and to the formation of secondary pores. The effect of boron was investigated by means of Secondary Ion Mass Spectrometry (SIMS) supported by Scanning Electron Microscopy (SEM) and Light Microscopy (LM). To verify the influence of the process parameters on the mechanical properties, the microstructure (pore shape) was examined and impact energy measurements were performed.The concentrations of B in different samples were varied from 0.03–0.6 weight percent (wt%). Higher boron concentrations are detectable by EPMA, whereas the distributions of boron in the samples with interesting overall concentration in the low wt% range are only detectable by means of SIMS.This work shows that the distribution of boron strongly depends on its concentration and the sintering atmosphere used. At low concentration (up to 0.1 wt%) there are boride precipitations; at higher concentration there is a eutectic iron–boron grain boundary network. There is a decrease of the impact energy observed that correlates with the amount of eutectic phase.     

An effect of residual gas component on detected secondary ions during TOF‐SIMS depth profiling and a method to estimate contained component

With regard to Secondary Ion Mass Spectroscopy (SIMS) measurement of atmospheric gas elements, a problem occurs that the detected signal includes background components caused by residual gas along with contained components. Relating to this issue, an available method to quantify the contained components by separating the background ones had been established for Dynamic SIMS. Time‐of‐Flight SIMS with sputtering ion gun has also applied for depth profiling as well as Dynamic SIMS. However, few studies have attempted to investigate the secondary ion behavior of the atmospheric gas elements for depth profiling by Time‐of‐flight SIMS, especially for low concentration levels. In this study, experimental examinations of the secondary ions of the atmospheric gas elements, such as oxygen, hydrogen, and carbon in the silicon substrate, has been conducted in various analytical conditions of TOF‐SIMS depth profiling mode. Under the analytical conditions of our study, it has been proved that the background intensity of these elements was correlated to the sputtering rate. For the analysis of Floating Zone Silicon substrate, the oxygen intensity of the background component was proportional to the inverse number of the sputtering rate. Based on these facts, the total detected intensity of the atmospheric gas elements was able to be separated into the contained components and background ones by changing the sputtering rate during TOF‐SIMS measurement. An experimental result has shown that the contained oxygen concentration in the Czochralsk Silicon substrate estimated by the “TOF‐SIMS Raster Change Method” has successfully agreed with the result by the Dynamic SIMS.     

High performance collision cross section calculation—HPCCS

Since the commercial introduction of Ion Mobility coupled with Mass Spectrometry (IM‐MS) devices in 2003, a large number of research laboratories have embraced the technique. IM‐MS is a fairly rapid experiment used as a molecular separation tool and to obtain structural information. The interpretation of IM‐MS data is still challenging and relies heavily on theoretical calculations of the molecule's collision cross section (CCS) against a buffer gas. Here, a new software (HPCCS ) is presented, which performs CCS calculations using high perfomance computing techniques. Based on the trajectory method, HPCCS can accurately calculate CCS for a great variety of molecules, ranging from small organic molecules to large protein complexes, using helium or nitrogen as buffer gas with considerable gains in computer time compared to publicly available codes under the same level of theory. HPCCS is available as free software under the Academic Use License at https://github.com/cepid-cces/hpccs . © 2018 Wiley Periodicals, Inc.     

Refolding and simultaneous purification of recombinant human proinsulin from inclusion bodies on protein‐folding liquid‐chromatography columns

Protein‐folding liquid chromatography (PFLC) is an effective and scalable method for protein renaturation with simultaneous purification. However, it has been a challenge to fully refold inclusion bodies in a PFLC column. In this work, refolding with simultaneous purification of recombinant human proinsulin (rhPI) from inclusion bodies from Escherichia coli were investigated using the surface of stationary phases in immobilized metal ion affinity chromatography (IMAC) and high‐performance size‐exclusion chromatography (HPSEC). The results indicated that both the ligand structure on the surface of the stationary phase and the composition of the mobile phase (elution buffer) influenced refolding of rhPI. Under optimized chromatographic conditions, the mass recoveries of IMAC column and HPSEC column were 77.8 and 56.8% with purifies of 97.6 and 93.7%, respectively. These results also indicated that the IMAC column fails to refold rhPI, and the HPSEC column enables efficient refolding of rhPI with a low‐urea gradient‐elution method. The refolded rhPI was characterized by circular dichroism spectroscopy. The molecular weight of the converted human insulin was further confirmed with SDS–18% PAGE, Matrix‐Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry (MALDI‐TOF‐MS) and the biological activity assay by HP‐RPLC. Copyright © 2014 John Wiley & Sons, Ltd.