January's Paper of the Month

 Rare-earth perovskite transition metals have been shown to have properties ideal for semi-conductor devices which are commonly used in electronic circuits.  

Rare-earth perovskite transition metals have been shown to have properties ideal for semi-conductor devices which are commonly used in electronic circuits.  

As the modern world advances and our reliance on technology increases, it becomes necessary to improve the efficiency of semi-conducting materials. Semi-conductors are commonly used as diodes and transistors in devices such as microprocessors. Research into these materials is one of paramount importance. 

Recent studies have found transition metal oxides to have incredible electric, magnetic and superconducting properties, potentially ideal for semiconductors. LaAlO3 and SrTiO3 are wide band gap insulators with perovskite-based structures which are commonly used as substrates for functional oxide thin films. 

However, thin films of these oxides are not of much use except as high-k dielectrics. They require the addition of ions to tune their electronic band structure and thus improve their magnetic and optical properties. It is the interface between these oxides which prove to be the most interesting, their interaction induces magnetic and conductive properties from otherwise non-magnetic, insulating oxides. 

LaAlO3 is a rare-earth based perovskite transition metal oxide. Naturally such materials are isolated as crystals and it is important to understand the native characteristics if we are to better understand thin film behaviour. 

Due to its high-k dielectric properties, LaAlO3 is a promising material for metal oxide-based semiconductor devices. However, concern has been raised in several studies regarding leakage-current which is caused by structural defects. Understanding these defects theoretically and experimentally is of utmost importance for better use of such materials in optical and electronic applications. 

It has also been discovered that lattice strain affects the role and dynamics of defects. Previous work has also demonstrated that phase transitions can occur when samples are placed under certain temperatures. Current theories also suggest that specific engineering of these defects can provide several different functionalities for transition metal oxides. Raman spectroscopy further provides a useful method of probing these defects. 

January’s Paper of the Month is a collective effort from the National University of Singapore, Nanyang Technological University and Trinity College Dublin. Their paper explored novel magnetic excitations using Raman spectroscopy to probe LaAlO3 and several other polar oxide substrates. 

They built on the idea that a host of robust defects present in LaAlO3 could be promising in providing new functions with controlled engineering. The group conducted magnetic field dependant Raman spectroscopic studies at low temperatures to gain a better understanding of lattice phonons and the functionalities of these defects. 

The low temperature Raman spectroscopy was conducted using a WiTec Raman spectrometer and a Linkam HFS600-PB4 with LNP, allowing a temperature range from -196°C to 600°C.

 The HFS set up with liquid nitrogen cooling and a WiTec Raman Spectrometer. 

The HFS set up with liquid nitrogen cooling and a WiTec Raman Spectrometer. 

When discussing the purpose of the Linkam stage, Dr. Surajit Saha said: “The HFS was used to perform temperature dependence of the angular momentum states over a range of 80 to 300 K (-193°C to 26°C). It was useful because we could probe the decay of the angular momentum states with increasing temperature which was not possible to perform with our existing variable temperature setup.”

The low temperature experiments provided evidence for novel transitions which disappear at room temperature. These transitions were found to be magnetically sensitive, suggesting a magnetic degree of freedom caused by the defects. 

They further discovered that the key to magnetic sensitive field states is the presence of a heavy element within the transition metal oxide. These angular momentum states and the magnetic interactions can be tailored for novel optical applications. The magnetic degrees of freedom may potentially be tuned and optimised in rare earth perovskites for optical applications. 

The group’s findings pave the way for further experimentation and testing to better understand the complexities of transition metal oxides. 

By Tabassum Mujtaba

Saha, S. et al. Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering Study. Sci. Rep. 6, 36859; doi: 10.1038/srep36859 (2016)

 

Visionary Technology

 Thermochromic crystals may provide a non-invasive method of determining whether foods have been exposed to destructive temperatures.

Thermochromic crystals may provide a non-invasive method of determining whether foods have been exposed to destructive temperatures.

To be able to accurately gauge the temperature of an object by sight, rather than touch, is a useful method of heat detection and it can also be an excellent safety precaution. 

Such a phenomenon does exist in the form of thermochromic crystals which transition in colour when subjected to heat. The practical application of such substances is diverse, ranging from colour changing baby bottles and novelty mugs to medical devices. 

Josephine Mueller and Taylor Lauster, of North Central College Illinois, USA, conducted thermal microscopy experiments of thermochromic crystals and highlighted a potential application for such crystals in food packaging. 

The students worked alongside The McCrone Group, our partners in the US, who graciously donated a Linkam FTIR600 stage. 

Although designed for infra-red analysis, the students used the heating feature of the FTIR600 to conduct simple heating and cooling experiments on the thermochromic crystals, with the aim of finding potential applications for thermochromism in industry. The quartz window also allowed image capture of the crystals during the experiment.

The study focused on the idea that if a crystal was to be permanently deformed after exposure to a given temperature, this would be a good method of monitoring thermal conditions of food items in transit. Such crystals could be placed within food packaging and their permanent deformation would indicate exposure to destructive temperatures. 

To test the suitability of thermochromic crystals for such an application, the students first grew their own thermochromic crystal - (DEA)2CuCl4

For their thermal analysis study, the crystals were heated from room temperature up to 70°C and cooled back down to room temperature. Below are images captured during the heating and cooling of the thermochromic crystal (courtesy of Taylor and Josephine).

 Initial sample of (DEA) 2 CuCl 4  using a 50X objective. The sample has a strong green colour. 

Initial sample of (DEA)2CuCl4 using a 50X objective. The sample has a strong green colour. 

 Melted sample of (DEA) 2 CuCl 4   at 50°C, note a change in colour from green to an orange-green. 

Melted sample of (DEA)2CuCl4  at 50°C, note a change in colour from green to an orange-green. 

 Melted sample of (DEA) 2 CuCl 4  at 56°C. Most of the sample has now lost the green colouring. 

Melted sample of (DEA)2CuCl4 at 56°C. Most of the sample has now lost the green colouring. 

 Fully melted sample of (DEA) 2 CuCl 4  at 70°C, now an orange colour.

Fully melted sample of (DEA)2CuCl4 at 70°C, now an orange colour.

 Sample of (DEA) 2 CuCl 4   cooled to room temperature, returning to the original green colour. 

Sample of (DEA)2CuCl4  cooled to room temperature, returning to the original green colour. 

Their results showed the thermochromic change to be reversible for (DEA)2CuCl4 . There appears to be slight structural integrity loss after cooling, but the discrepancies are not obvious to the eye and would require microscopic analysis.

Although these particular crystals are not suitable as temperature determinants in food packaging, their study is a great step forward into improving the transportation of goods. Work must now be done in developing a non-toxic thermochromic crystal which has permanent deformation at destructive temperatures.  

We would like to thank Josephine, Taylor and The McCrone group for their innovative study and for kindly sharing their findings with us. 

By Tabassum Mujtaba

December's Paper of the Month

 The dynamic nature of self-healing molecules can be attributed to the reversible cross-linking of functional end-groups. 

The dynamic nature of self-healing molecules can be attributed to the reversible cross-linking of functional end-groups. 

Self-healing in materials is the process by which materials reassemble after applications of stress. In everyday life, we often suffer from small bumps and grazes which we very quickly recover from. This process is an essential feature of living systems which helps to avoid sustaining permanent damage. 

The idea of self-healing has been of great interest in the materials field in recent years. If these properties could be emulated in synthetic materials, the applications would be vast. This year alone has seen many devastating earthquakes and tsunamis, the development of self-healing materials in buildings could help save millions of lives. 

December’s Paper of the Month comes from Yan et al., from Martin Luther University Halle-Wittenberg, who have been working on recreating self-healing in synthetic materials by incorporating it as an intrinsic dynamic network. 

Self-healing occurs when dynamic bond interactions break when stress is applied, but - with time - reform and restore the strength of the material. These types of bonds can be incorporated into the load carrying molecular backbone of a polymer which encourages the self-healing properties. 

For such a system to work the bond interactions of the material must be dynamic, thus weak bond interactions, which are more readily formed and broken, can be exploited. The molecular scaffold should also incorporate a matrix in which the reformation of bonds can occur. 

Previous work suggested that the time for self-healing is related to the time of relaxation of molecular processes. The relationship between the molecular relaxation process and self-healing has been analysed but the processes behind the self-healing were not elucidated. 
To uncover these processes, Yan et al., used a reversible network of telechelic polymers and conducted small angle x-ray scattering and rheological experiments. 

For clear analysis, the network formed by the molecules needs to be well controlled and structured but this is often difficult to achieve. In their experiments, Small Angle X-ray Scattering (SAXS) was used to prove the molecules form a network of small aggregates, which form through self-assembly and become weaker at elevated temperatures. They used a custom made HFS91 Capillary Stage adapted for vacuum in their heated Small-Angle X-ray Scattering experiments. This enabled them to investigate the relaxation process of the material. 

They used telechelic polyisobutylene (PIB) as the relaxation processes of the material were well separated. This in turn allowed them to analyse how the healing process was related to the relaxation of the molecule.
 
Their experiments underlined the molecular processes of healing, allowing them to envision common design rules. With more work, their findings can be used to create better self-healing molecules in the future. 

By Tabassum Mujtaba

Yan, T. et al. Unveiling the molecular mechanism of self-healing in a telechelic, supramolecular polymer network. Sci. Rep. 6, 32356; doi: 10.1038/srep32356 (2016).

Touchdown in Denver

 The Sports Authority Field at Mile High in Denver, home of the current NFL champions. 

The Sports Authority Field at Mile High in Denver, home of the current NFL champions. 

Our sales team recently visited Colorado for the American Association of Pharmaceutical Scientists (AAPS) 2016 annual meeting.  

Industrial and academic delegates from all over the globe descended on the Mile High city of Denver to attend the meeting which covered a diverse range of topics: from drug product manufacturing and stem cell research, to novel pharmaceutical technology. 

Freeze drying and differential scanning calorimetry (DSC) are important techniques in the pharmaceutical industry and we were excited to be showcasing two new stages at AAPS: the optical DSC450 stage and the freeze-drying vial system FDVS

DSC is a technique used to measure temperature and heat flow associated with thermal transitions in materials.  The optical DSC450 system has been optimised to combine the measurement of transition temperatures and enthalpy changes while simultaneously imaging the sample, providing additional information about changes in morphology and colour. 

The Freeze Drying Vial System (FDVS) has been designed as a turn-key solution for simulating the industrial freeze drying process in a compact and efficient form. By incorporating vials, the FDVS works with a small sample volume and uses enough to simulate large scale industrial processes while still minimising sample wastage.

We also brought our humidity controller RH95, freeze drying cryostage FDCS and heating and cooling stage THMS600 which again proved popular within the market. The show reiterated the importance of sample characterisation within the pharmaceutical industry and the role Linkam has within it. 

 Ricky Patel and Duncan Stacey outside the McCrone building in Illinois.

Ricky Patel and Duncan Stacey outside the McCrone building in Illinois.

While in the US, we also caught up with our American distributors – the McCrone Group. They graciously showed us around their facilities, including the famous Hooke College and gave us a tour of their private microscopy museum which has a collection of microscopes from the 17th century. We were treated to the delights of Chicago’s famous dining scene - and we are still trying to work off the additional weight!

We would like to give a big thank you to all those who came to see us at the show. We look forward to seeing you at the next pharmaceutical conference.  

By Tabassum Mujtaba

 

November's Paper of the Month

 Due to its unique properties Graphene (an allotrope of carbon) has incredible potential for application in many different fields. 

Due to its unique properties Graphene (an allotrope of carbon) has incredible potential for application in many different fields. 

Graphene has been a hot topic in both fundamental science and practical applications since it was first isolated in 2004. It is the most conductive material known and has many other attractive properties such as flexibility, transparency and impermeability. This makes it suitable for application in wide-ranging areas such as sanitation, biomedical science and electronics. 

The incredible features and applications of this material can be generated by adding layers of graphene on top of a single graphene layer. The interlayer shear modes in these few-layer graphene are very important for understanding their exceptional properties. However, these modes are in very low frequency range with very weak intensities which greatly hinders exploration.

This month’s Paper of the Month comes from Nanyang Technological University, in Singapore. Cong, currently a professor of Fudan University, and Ting demonstrated methods of improving intensities of the shear modes of graphene layers which would in turn allow better probing of few-layer graphene itself and exploration of its application. 

Cong and Ting discovered a way to enhance such interlayer shear modes through folding the bernal-stacked graphene layers with certain twisting angles. They used Linkam’s electrical probe stage, the HFS600E-PB4, which has a temperature range of -196°C to 600°C in their temperature dependant in-situ Raman spectroscopy experiments. 

When asked to comment on the motivation behind their work, and the purpose of the Linkam stage, Dr Cong said: 

“Investigations of shear modes in few-layer graphene are greatly hindered by the truth that shear modes of graphene layers are extremely weak and almost fully blocked by a Rayleigh rejecter in Raman measurements. 

We found that the shear modes could be dramatically enhanced by properly folding graphene layers. Such strong signals offer the feasibility of performing systematically in-situ temperature Raman scattering measurements with the help of a Linkam stage. The vibrational symmetry, anharmonicity and electron-phonon coupling of the shear modes of graphene layers are uncovered through studies of temperature-dependent Raman spectroscopy. 

The Linkam stage which is compatible with our confocal low-frequency Raman system, helps us to realize the temperature-dependent Raman measurement with liquid nitrogen”.

Their research will provide a better insight into the mechanical and electrical properties of graphene. 

By Tabassum Mujtaba

Cong, C. & Ting, Y. Enhanced ultra-low-frequency interlayer shear modes in folded graphene layers. Nat Commun. 5:4709 | DOI: 10.1038/ncomms5709 (2014). 

 

Reaching New Peaks

 Denver, Colorado is the location for this year’s AAPS annual meeting

Denver, Colorado is the location for this year’s AAPS annual meeting

The Colorado city of Denver, nick-named the Mile-High City because its elevation is exactly one mile above sea level, is a gateway to the snow-capped Rocky Mountains. This year it plays host to the American Association of Pharmaceutical Scientists (AAPS) 2016 annual meeting. 

This week, from 13th to 16th November, the Linkam sales team will be heading to the Colorado Convention Centre for this year’s meeting. We will be bringing our humidity generator RH95, the thermal stage THMS600 and the freeze drying cryo-stage FDCS196.

We are also excited to be announcing the launch of two new Linkam stages – a brand new vial based freeze drying system and a dual pan optical DSC. 

Many of our products are perfect for sample characterisation in the pharmaceutical market. They can be used for a variety of applications including quality assurance, developing freeze drying protocols, dissolution studies and many more.

Come and see us on booth 1470 to discuss how our stages can enhance your sample characterisation needs.

We look forward to seeing you there. 

September's Paper of the Month

From the mating dance of the peacock spider to brood parasitism in the common cuckoo, behavioural ecology is a fascinating and complex science. It is defined as the study of the evolutionary behaviour of animals due to ecological selection pressures, and even the smallest of organisms such as bacteria can effectively emulate eukaryotic social behaviours. 

Streptomycetes are one such genus which can form multi-cellular colonies with distinct multi-nucleated hyphae structures. These hyphae have distinct compartments separated through infrequent cross-walls. The group is also significant due to their medicinal purpose; they produce over half of the world’s antibacterial and antiparasitic drugs and are commonly known for their forest like smell caused by the organic compound Geosmin. 

The group harbour perplexing traits and behaviours. When mechanically macerated, the hyphae surprisingly do not ‘bleed’ to death suggesting the end is plugged and compartmentalised. Furthermore, growing hyphal tips can form up to 100 septa and in such multi-nucleated species, which lack DNA damage control proteins, we are left wondering how DNA can be protected from intense intra-cellular movement. 

September’s Paper of the Month is a collaboration between the laboratory of Professor Gilles Van Wezel and the Koster laboratory and their work using the CMS196M to answer the questions surrounding the complex behaviour of Streptomyces albus.

Read more...

Underground at St Pancras

When you next take a train from St Pancras have a think about what might be going on beneath your feet.

Just across the road from the station, and 28 metres below the pavement, world leaders in their field are working with some of the highest resolution microscopes on the market to investigate the causes of cancer and other diseases. 

The recently opened Frances Crick Institute brings together scientists from all over the world under one roof and is a partnership between Cancer Research UK, Imperial College, King's College, the Medical Research Council, University College London and the Wellcome Trust. 

I was privileged to be invited to visit recently and I would like to thank the Head of Electron Microscopy, Lucy Collinson, and her colleague, Marie Charlotte, for an extremely interesting tour of the labs. 

Read more... 

August's Paper of the Month

Thermophotovoltaics (TPV) is the conversion of thermal radiation released by a thermal emitter into electricity by means of a photovoltaic cell.

Power generation with a TPV system can be envisaged for almost any process and an absence of moving parts has the advantage of low maintenance costs. Thermal emission scales with temperature to a power of 4, meaning temperature above 1000 °C is required to generate significant power in such systems.

However, the wide spectral width of thermal radiation limits the efficiency of TPV conversion as only part of the spectrum is accepted by the photovoltaic cell. August’s Paper of the Month by Dyachenko et al., attempts to solve the TPV efficiency problem by designing and using a unique refractory metamaterial as an emitter instead of the traditional structural resonances.

Read more... 

 

Linkam in France: deuxième partie

 The Gateway College bridge crosses the river Rhone  in Lyon.

The Gateway College bridge crosses the river Rhone  in Lyon.

Renowned for its exquisite food, rich cultural history and annual Festival of Lights, Lyon is one of France’s most visited cities. We are excited to announce Linkam will be heading there soon. 

The European Microscopy Congress will take place at the Lyon Convention Centre from the 28th August to the 2nd September. This will be Linkam’s second trip to France this year after the highly successful European Materials Research Society spring meeting.

With over 2000 guests, several hundred guest speakers, specialised workshops and symposia covering the life sciences, instrumentation and methods and materials science, EMC will be an excellent platform to showcase our stages. 

We’ll be taking along the tensile TST350, cryo-correlative CMS196, dual pan DSC, humidity system RH95 and one of our electrical probe stages, the LTS420 E-PB4

Come over to booth 3 to discuss how our stages can enhance your sample characterisation needs - we look forward to seeing you there.