The quest for better medical imaging at MAX IV

Advances in the world of physics often quickly lead to advances in the world of medical diagnostics. From the moment Wilhelm Röntgen discovered X-rays he was using them to look through his wife’s hand.

A lot of the physics principles at the foundation of MAX IV are also at the foundation of medical imaging technologies such as nuclear magnetic resonance imaging, x-ray computed tomography and positron emission tomography.
Positron emission spectroscopy is more commonly known as PET imaging. It’s a method used to study metabolic processes in the body as a research tool but also to diagnose disease. An important use today is in the diagnosis of metastases in cancer patients, but it can also be used to diagnose certain types of dementia.

In PET, a positron-emitting radionuclide is injected into a patient and travels around the body until it accumulates somewhere, depending on the chemical composition. For example, the fluorine-18 radionuclide when bound to deoxyglucose accumulates in metabolically active cells which is useful for finding metastases. The radionuclide is unstable and emits positrons which is the antimatter equivalent of an electron. When a positron and an electron inevitably meet, they annihilate one another, producing two pulses of gamma radiation traveling in opposite directions. By placing a detector around a patient, it is possible to measure the gamma radiation and convert the signal into something that can be more easily measured. These detectors are made up of materials known as scintillators which take high energy radiation and emit lower energy radiation that can be detected using fast photodetectors – photomultiplier tubes.

>Read more on the MAX IV Laboratory website


Expanding the infrared nanospectroscopy window

The ability to investigate heterogeneous materials at nanometer scales and far-infrared energies will benefit a wide range of fields, from condensed matter physics to biology.

Scientific studies require tools that match the natural length and energy scales of the phenomena under investigation. For many questions in biology, quantum materials, and electronics, this means nanometer spatial resolution combined with far-infrared energies. For example, scientists might want to study collective electron oscillations in quantum materials for optoelectronic circuits, or the characteristic vibration modes of protein molecules in biological systems.

A recently developed infrared technique—synchrotron infrared nanospectroscopy (SINS)—combines broadband synchrotron light with atomic-force microscopes to enable infrared imaging and spectroscopy at the nanoscale. However, the technique could only be used in a narrow range of the electromagnetic spectrum that excluded far-infrared wavelengths, due to a scarcity of suitable light sources and detectors for that range. In this work, researchers extended SINS to far-infrared wavelengths, opening up a whole new experimental regime.

> Read more on the Advanced Lightsource at Berkeley Lab website

Image: Left: Nanoscale images of SiO2 hole array, obtained using atomic-force microscopy (AFM, top) and synchrotron infrared nanospectroscopy (SINS, bottom), demonstrating SINS contrast between patterned SiO2 and underlying Si substrate with ~30 nm spatial resolution (inset). Scale bar = 200 nm. Right: SINS broadband spectroscopic data for SiO2, taken along dotted line in images at left, showing amplitude (top) and phase (bottom) information from asymmetric  Si–O stretching (1200 cm–1) and bending (460 cm–1) modes. The lower-energy bending mode had previously been inaccessible with this technique.

Direct Observation of the Kinetics of Gas–Solid Reactions

… using in-situ kinetic and spectroscopic techniques.

Copper oxide is a widely used adsorptive material that removes trace amounts of H2S from various process streams via chemical reaction to form copper sulfide. At room temperature the thermodynamics favor a near complete conversion of CuO to copper sulfide in the presence of H2S. However, in application, the extent of conversion of the CuO to copper sulfide during reaction can be influenced by many factors, including the initial crystalline state of the CuO, and the rate at which solid products accumulate on the reactive surfaces or within pores of the CuO particles. This incomplete utilization of CuO is problematic for industrial applications because it typically leads to oversized equipment and/or frequent process shutdowns. Developing fundamental insight at the atomic scale for this reaction could overcome these limitations by providing a rational basis for the design of new materials and by leading to predictive models that allow for current materials to be operated toward their thermodynamic limits. Thus, experiments that combine reaction kinetic testing while also simultaneously capturing chemical and structural changes in the solid phase at multiple length scales are necessary to elucidate the fundamentals of these reactions at various length scales.

Previous studies were successful in semi-quantitatively relating properties of materials to performance in fixed-bed systems, however, differences in performance were often attributed to physical properties at the >10 mm scale (e.g., surface area, pore volume, bulk density). The effects of molecular scale material characteristics (e.g., microscopic shape, metal oxide crystallite size, and surface composition) were rarely investigated, thus, it is difficult to extend the conclusions from these studies across a broad range of conditions and materials.

>Read more on the SSRL at SLAC website

Image (extract): (A) CuO and CuS concentration maps derived from XANES analysis of TXM images of individual CuO particle during reaction with 1000 ppm H2S. (B) Fractional conversion versus time (derived from linear combination fitting of Cu K-edge XANES) of fixed beds of CuO particles consisting of 2 different crystallite sizes (red circles are 2.8 nm and blue squares are 28 nm) and of individual CuO particles. See the entire figure here.

Synchrotron infrared beamline optics optimized…

…for nano-scale vibrational spectroscopy. First experimental report of a special optical layout dedicated to correct typical aberrations derived from large extraction ports in IR beamlines.

Infrared nanospectroscopy represents a major breakthrough in chemical analysis since it allows the identification of nanomaterials via their natural (label free) vibrational signatures. Classically powered by laser sources, the experiment called scattering Scanning Near-field Optical Microscopy (s-SNOM) has become a standard tool for investigations of chemical and optical properties of materials beyond the diffraction limit of light.

Lately, s-SNOM is achieving unprecedent sensitivity range by exploring the outstanding spectral irradiance of synchrotron light sources in the full range of infrared (IR) radiation. In the last few years, the combination of s-SNOM and ultra-broadband IR synchrotron (SINS or nano-FTIR) has helped studies in relevant scientific fronts involving atomic layered materials, fundamental optics, nanostructured bio-materials and, very recently, it was demonstrated to be feasible to work in the far-IR.

IR ports in synchrotron storage rings can be up to a thousand times more brilliant than classical IR black body sources. This advantage allowed IR beamlines to be the only places capable of performing IR micro-spectroscopy for many years. However, in comparison to X-ray ports, IR beamlines require large apertures for allowing long wavelengths to be extracted. Consequently, IR beamlines typically present optical aberrations such as extended source depth and coma.

>Read more on the Brazilian Synchrotron Light Laboratory website

Images (extracts): Figure 1 – Proposed optical layout, IR extraction chamber indicating the source depth, conical mirror illustration, aberration-corrected focal spot at the sample stage and nano-FTIR experimental scheme in operation in the IR endstation of the LNLS. Figure adapted from R. Freitas et al., Optics Express 26, 11238 (2018).

SESAME hosts its first users

Mid July, the first users arrived at SESAME to perform experiments using the Centre’s XAFS/XRF (X-ray absorption fine structure/X-ray fluorescence) spectroscopy beamline, SESAME’s first beamline to come into operation.

This was the Finnish Kirsi Lorentz and three of her colleagues at The Cyprus Institute: the Cypriot Grigoria Ioannou, the Japanese Yuko Miyauchi and the Greek/Egyptian Iosif Hafez, who together form a true international team in the spirit of SESAME.

Kirsi is the author of one of the 19 proposals from 5 of the SESAME Members (Cyprus, Egypt, Jordan, Pakistan and Turkey) that have been recommended for a total of 95.8 hour shifts on the XAFS/XRF beamline by SESAME’s Proposal Review Committee (PRC). The PRC is an international advisory body that evaluates the scientific and technological merit of proposals from the General Users and determines their priority using criteria based on IUPAP’s Recommendations for the Use of Major Physics Users Facilities.

“This heralds in a new stage in SESAME’s march forward, and for scientists in the SESAME Members and the region it is the tangible beginning of a moment from when it becomes possible to carry out state-of-the-art research in the region” said Khaled Toukan, Director of SESAME.

 “It is a unique opportunity and a real honour to be the first user of a synchrotron light facility – a research visit to remember” said Kirsi, who is examining ancient human remains from the Eastern Mediterranean and the Near East, adding “we are very excited with the results we obtained at the SESAME XAFS/XRF beamline, and grateful to all those who have worked so hard to bring this crucial research facility into operation in our region”.

>Read more on the SESAME website

Picture: Kirsi Lorentz, The Cyprus Institute: Kirsi Lorentz and her research team (from left to right: Yuko Miyauchi, Grigoria Ioannou, Kirsi Lorentz and Iosif Hafez) at the XAFS/XRF beamline control hutch.

High-caliber research launches NSLS-II beamline into operations

Pratt & Whitney conduct the first experiments at a new National Synchrotron Light Source II beamline.

A new experimental station (beamline) has begun operations at the National Synchrotron Light Source II (NSLS-II)—a U.S. Department of Energy (DOE) Office of Science User Facility at DOE’s Brookhaven National Laboratory. Called the Beamline for Materials Measurement (BMM), it offers scientists state-of-the-art technology for using a classic synchrotron technique: x-ray absorption spectroscopy.

“There are critical questions in all areas of science that can be solved using x-ray absorption spectroscopy, from energy sciences and catalysis to geochemistry and materials science,” said Bruce Ravel, a physicist at the National Institute of Standards and Technology (NIST), which constructed and operates BMM through a partnership with NSLS-II.

X-ray absorption spectroscopy is a research technique that was developed in the 1980s and, since then, has been at the forefront of scientific discovery.

“The reason we’ve used this technique for 40 years and the reason why NIST built the BMM beamline is because it adds a great value to the scientific community,” Ravel explained.

The first group of researchers to conduct experiments at BMM came from jet engine manufacturer Pratt & Whitney. Senior Engineer Chris Pelliccione and colleagues used BMM to study the chemistry of jet engines.

>Read more on the National Synchrotron Light Source II (NSLS-II) website

Image: Pratt & Whitney Senior Engineer Chris Pelliccione (left) with NIST’s Bruce Ravel (right) at BMM’s workstation.

An electrifying view on catalysis

The future of chemistry is ‘electrifying’: With increasing availability of cheap electrical energy from renewables, it will soon become possible to drive many chemical processes by electrical power. In this way, chemical products and fuels can be produced via sustainable routes, replacing current processes which are based on fossil fuels.

In most cases, such electrically driven reactions make use of so-called electrocatalysts, complex materials which are assembled from a large number of chemical componentAs. The electrocatalyst plays an essential role: It helps to run the chemical reaction while keeping the loss of energy minimal, thereby saving as much renewable energy as possible. In most cases, electrocatalysts are developed empirically and the chemical reactions at their interfaces are poorly understood. A better understanding of these processes is essential, however, for fast development of new electrocatalysts and for a directed improvement of their lifetime, one of the most important factors that currently limit their applicability.

>Read more on the Elettra website

Figure:  Introducing well-defined model electrocatalysts into the field of electrochemistry.

Research shows how to improve the bond between implants and bone

Research carried out recently at the Canadian Light Source (CLS) in Saskatoon has revealed promising information about how to build a better dental implant, one that integrates more readily with bone to reduce the risk of failure.

“There are millions of dental and orthopedic implants placed every year in North America and a certain number of them always fail, even in healthy people with healthy bone,” said Kathryn Grandfield, assistant professor in the Department of Materials Science and Engineering at McMaster University in Hamilton.

A dental implant restores function after a tooth is lost or removed. It is usually a screw shaped implant that is placed in the jaw bone and acts as the tooth roots, while an artificial tooth is placed on top. The implant portion is the artificial root that holds an artificial tooth in place.

Grandfield led a study that showed altering the surface of a titanium implant improved its connection to the surrounding bone. It is a finding that may well be applicable to other kinds of metal implants, including engineered knees and hips, and even plates used to secure bone fractures.

About three million people in North America receive dental implants annually. While the failure rate is only one to two percent, “one or two percent of three million is a lot,” she said. Orthopedic implants fail up to five per cent of the time within the first 10 years; the expected life of these devices is about 20 to 25 years, she added.

“What we’re trying to discover is why they fail, and why the implants that are successful work. Our goal is to understand the bone-implant interface in order to improve the design of implants.”

>Read more on the Canadian Light Source website

SESAME light source brings second beamline into service

Allan, Jordan, 30 April 2018. At 11:21 pm local time (GMT +3) scientists at the SESAME light source brought the laboratory’s infrared (IR) spectromicroscopy beamline into service for the first time.

This beamline is a completely new beamline. It was designed and built in collaboration with the French Soleil Synchrotron. It is SESAME’s second operational beamline, and it joins an X-ray beamline that saw first light on 23 November 2017. The addition of the IR beamline will enable the application of infrared microspectroscopy and imaging in a wide range of fields, including surface and materials science (e.g. characterization of new nanomaterials for solar cell fabrication and for drug delivery mechanisms), biochemistry, archaeology, geology, cell biology, biomedical diagnostics and environmental science (e.g. air and water pollution)

“I’ve been waiting a long time for this moment,” said Gihan Kamel, SESAME’s IR beamline scientist. “It’s very satisfying to see light in the beamline, and to be able to start doing research here that we previously had to travel to Europe to carry out.”

In preparation for the SESAME research programme, a number of thematic schools are being held across the region in a collaboration involving SESAME and European partners including the European Union through its Open SESAME project. One of these was held at SESAME earlier this month, covering science on the IR beamline. Students came from across the region and learned techniques ranging from sample preparation to data analysis.

“The infrared beamline has a mouth-watering research programme lined up,” said SESAME Scientific Director Giorgio Paolucci, “and it is great to see so many young people from across the region preparing to embark on careers in science.”

>Read more on the SESAME website

New class of single atoms catalysts for carbon nanotubes

They exhibit outstanding electrochemical reduction of CO2 to CO.

Experiments using X-rays on two beamlines at the Australian Synchrotron have helped characterise a new class of single atom catalysts (SACs) supported on carbon nanotubes that exhibit outstanding electrochemical reduction of CO2 to CO. A weight loading of 20 wt% for the new class, nickel single atom nitrogen doped carbon nanotubes (NiSA-N-CNTs), is believed to be the highest metal loading for SACs reported to date.

Single atoms of nickel, cobalt and iron were supported on nitrogen doped carbon nanotubes via a one-pot pyrolysis method and compared in the study.

A large international collaboration, led by Prof San Ping Jiang, Deputy Director of the Fuels and Energy Technology Institute at the Curtin University of Technology and associates from the Department of Chemical Engineering, have developed a new synthesis and development process for nitrogen-doped carbon nanotubes with a nickel ligand that demonstrate high catalytic activity.

The study was published in Advanced Materials and featured on the inside cover of the publication.

Dr Bernt Johannessen, instrument scientist on the X-ray absorption spectroscopy (XAS) beamline at the Australian Synchrotron was a co-author on the paper, which also included lead investigators from Curtin University of Technology and collaborators at the University of Western Australia, Institute of Metal Research (China), Oak Ridge National Laboratory (US), University of the Sunshine Coast, University of Queensland, Tsinghua University (China) and King Abdulaziz University (Saudi Arabia). Technical support and advice on the soft X-ray spectroscopy experiments was provided by Australian Synchrotron instrument scientist Dr Bruce Cowie.

>Read more on the Australian Synchrotron website

Image: extract of the cover of Advanced Materials.

Tailoring the surface chemical reactivity of transition‐metal dichalcogenide PtTe2 crystals

Recently, the PtX2 (X=S, Se, Te) class of transition-metal dichalcogenides has emerged as one of the most promising among layered materials “beyond graphene” for the presence of high room-temperature electron mobility and, moreover, bulk type-II Dirac fermions, arising from a tilted Dirac cone.
Information on the ambient stability of PtTe2 is a crucial step in order to evaluate the feasibility of its exploitation in technology. Moreover, the possibility to tune surface chemical reactivity by appropriate surface modification is an essential step for its employment for diverse applications, especially in catalysis.
By means of experiments with several surface-science spectroscopies and density functional theory, an international team of researchers from Italy, Republic of Korea, and Taiwan (coordinated by Graphene Labs of Istituto Italiano di Tecnologia) has investigated the reactivity of the PtTe2 surface toward most common ambient gases (oxygen and water), under the framework of the European Graphene Flagship-Core1 project.
To assess the surface chemical reactivity of PtTe2, X-ray photoelectron spectroscopy (XPS) carried out at the APE-HE beamline has been combined with high-resolution electron energy loss (HREELS) experiments and with density functional theory.
From the analysis of Te 3d core-level spectra in XPS and from the featureless vibrational spectrum in HREELS, it has been demonstrated that as-cleaved defect-free PtTe2 surface is inert toward most common ambient gases (oxygen and water).
In the evaluation of the ambient stability of PtTe2, the possible influence of Te vacancies on surface chemical reactivity deserves particular attention. As a matter of fact, Te vacancies may appear on non-stoichiometric samples during the growth process. To check the influence of Te vacancies on ambient stability of PtTe2, Te vacancies have been intentionally introduced in stoichiometric PtTe2 samples by Ar-ion sputtering. After exposing to O2 the PtTe2 surface defected by ion sputtering, with a Pt:Te ratio of 39:61, spectral features related to Te(IV) species appear, arising from the formation of Te=O bonds in a tellurium-oxide phase. The Te(IV) components are the most intense lines in the Te 3d XPS spectra for the case of air-exposed defected samples (see Figure 1). Concerning reactivity to water, it adsorbs molecularly even at room temperature on defected PtTe2. These findings also imply that the presence of Te vacancies is able to jeopardize the ambient stability of uncapped PtTe2-based devices, with a subsequent necessity to reduce the amount of Te vacancies for a successful technological exploitation of PtTe2.

>Read more on the Elettra website

Figure: XPS spectra of Te-3d core levels acquired for: defected PtTe2 (green curve), the same surface exposed to 106 L of O2 (black curve) and air-exposed defected PtTe2 (yellow curve). The photon energy is 745 eV. 

Investigation of metal deposition in organs after joint replacement

Synchrotron analysis shows potentially harmful metals from implants can find their way into human organs.

The hip replacement is considered to be one of the most successful orthopaedic interventions, with 75,000 performed each year by the NHS alone. However, the implants used to replace hips contain metals, such as chromium and cobalt, which are potentially toxic and which can be deposited into tissues around the implant site due to wear and corrosion. A team of researchers used X-ray absorption spectroscopy (XAS) on the I18 beamline to show that these metals can also find their way into organ tissues. Their results suggest that chronic diseases, such as diabetes, may create conditions in which mildly toxic trivalent chromium (CrIII) particles from replacement joints are reoxidised within the body to form carcinogenic hexavalent chromium (CrVI). Their results have been published in the Journal of Trace Elements in Medicine and Biology.

>Read more on the Diamond Light Source website

Image: Overview of the study (entire figure to see here).

Cleaner diesel emissions

More effective control of diesel nitrogen oxides through dosed addition of ammonia

In diesel engines, the burning of the fuel releases nitrogen oxides (NOx), which are harmful to human health. The automobile industry therefore developed a technique that reduces these emissions: Gaseous ammonia is added to the exhaust and, prompted by a catalyst, reacts with the nitrogen oxides to produce harmless nitrogen and water. At low temperatures, however, this process does not yet work optimally. Now, for the first time, scientists at the Paul Scherrer Institute PSI have found a remedy which is based on observations at the molecular level: The precise amount of added ammonia needs to be varied depending on the temperature. With this knowledge, manufacturers can improve the effectiveness of their catalytic converters for diesel vehicles. The researchers have now published their findings in the journal Nature Catalysis.

>Read more on the Paul Scherrer Institute website

Image: At the X-ray beam line: Davide Ferri (left) and Maarten Nachtegaal at the SLS experimental station where they studied diesel catalysis.
Photo: Paul Scherrer Institute/Markus Fischer

Apply for the Kai Siegbahn prize 2018

The Prize was established in 2009 in honour of Kai Siegbahn, founder of Nuclear Instruments and Methods A (NIMA), who had a strong and lasting commitment to advancing synchrotron radiation science.

The Editorial Board of NIMA is currently accepting nominations for the 2018 award, and we are counting on you to help us identify potential honorees! We invite you to review the award criteria, and to nominate a worthy colleague.

All nominations should be submitted to the Committee Chair by March 31 2018:

Prof. Fulvio Parmigiani, Kai Siegbahn Chair
Department of Physics, University of Trieste
International Faculty, University of Cologne,
Elettra Sincrotrone Trieste S.C.p.A.

Nomination criteria:

The Prize aims to recognize and encourage outstanding experimental achievements in synchrotron radiation research with a significant component of instrument development. Particular preference will be given to the development of synchrotron radiation spectroscopies.

Rules and eligibility:

Nominations are open to scientists of all nationalities without regard to the geographical site at which the work was performed. Usually, the prize shall be awarded to one person but it may be shared if all recipients have contributed to the same accomplishment. The prize recipient should be 45 years old or younger at the time of selection.

Nominations are accepted from the NIMA advisory board, the NIMA board of editors, synchrotron radiation facility directors as well as from scientists engaged in synchrotron radiation science. Nomination packages should include a nominating letter, at least one supporting letter, a list of five papers on which the award is based as well as a proposed citation for the award.

High coherence and intensity at FERMI enables new X-ray interfacial probe

Interfaces are involved in a wide range of systems and have significant implications in many fields of scientific and technological advancement, often determining device performance or chemical reactivity. Vital examples include solar cells, protein folding, and computer chips. A class of commonly used surface science techniques are comprised of even-ordered nonlinear spectroscopies (i.e., second harmonic and sum frequency generation) which exhibit no response in centrosymmetric media due to symmetry constraints.As a result, they have been widely used at optical wavelengths to explore physical and chemical properties of interfaces, where centrosymmetry is broken. Extending this to x-ray wavelengths would effectively combine the element specificity and spectral sensitivity of x-ray spectroscopy with the rigorous interfacial/surface specificity of optical even-ordered nonlinear spectroscopies. Unfortunately, at hard x-ray energies (x-ray wavelength order of the spacing between atoms) these even-ordered nonlinear spectroscopies are effectively bulk probes, as each individual atom breaks inversion symmetry. As soft x-ray wavelengths fall in between the UV and hard x-ray regimes, there has been uncertainty regarding the interface specificity of soft x-ray second harmonic generation.

>Read more on the FERMI webpage

Figure: (extract)  Experimental Design. X-ray pulses are passed through a 2 mm iris and focused onto the graphite sample at normal incidence. The transmitted beam is then passed through a 600 nm aluminum filter and onto a spectrometer grating, spatially resolving the second harmonic signal from the fundamental. Inset: A schematic energy level diagram of the second harmonic generation process. (entire figure here)


Questioning the universality of the charge density wave nature…

… in electron-doped cuprates

The first superconductor materials discovered offer no electrical resistance to a current only at extremely low temperatures (less than 30 K or −243.2°C). The discovery of materials that show superconductivity at much higher temperatures (up to 138 K or −135°C) are called high-temperature superconductors (HTSC). For the last 30 years, scientists have researched cuprate materials, which contain copper-oxide planes in their structures, for their high-temperature superconducting abilities. To understand the superconducting behavior in the cuprates, researchers have looked to correlations with the charge density wave (CDW), caused by the ordered quantum field of electrons in the material. It has been assumed that the CDW in a normal (non-superconducting) state is indicative of the electron behavior at the lower temperature superconducting state. A team of scientists from SLAC, Japan, and Michigan compared the traits of superconducting and non-superconducting cuprate materials in the normal state to test if the CDW is correlated to superconductivity.

>Read more on the SSRL website

Picture: explanation in detail to read in the full scientific highlight (SSRL website)