Tag Archives: #fingerprints

Illuminating Invisible Bloody Fingerprints With A Fluorescent Polymer (Forensic Science / Chemistry)

Careful criminals usually clean a scene, wiping away visible blood and fingerprints. However, prints made with trace amounts of blood, invisible to the naked eye, could remain. Dyes can detect these hidden prints, but the dyes don’t work well on certain surfaces. Now, researchers reporting in ACS Applied Materials & Interfaces have developed a fluorescent polymer that binds to blood in a fingerprint — without damaging any DNA also on the surface — to create high-contrast images.

Fingerprints are critical pieces of forensic evidence because their whorls, loops and arches are unique to each person, and these patterns don’t change as people age. When violent crimes are committed, a culprit’s fingerprints inked in blood can be hard to see, especially if they tried to clean the scene. So, scientists usually use dyes to reveal this type of evidence, but some of them require complex techniques to develop the images, and busy backgrounds can complicate the analysis. In addition, some textured surfaces, such as wood, pose challenges for an identification. Fluorescent compounds can enhance the contrast between fingerprints and the surface on which they are deposited. However, to get a good and stable image, these molecules need to form strong bonds with molecules in the blood. So, Li-Juan Fan, Rongliang Ma and colleagues wanted to find a simple way to bind a fluorescent polymer to blood proteins so that they could detect clear fingerprints on many different surfaces.

The researchers modified a yellow-green fluorescent polymer they had previously developed by adding a second amino group, which allowed stable bonds to form between the polymer and blood serum albumin proteins. They dissolved the polymer and absorbed it into a cotton pad, which was placed on top of prints made with chicken blood on various surfaces, such as aluminum foil, multicolored plastic and painted wood. After a few minutes, they peeled off the pad, and then let it air-dry. All of the surfaces showed high contrast between the blood and background under blue-violet light and revealed details, including ridge endings, short ridges, whorls and sweat pores. These intricate patterns were distinguishable when the researchers contaminated the prints with mold and dust, and they lasted for at least 600 days in storage. In another set of experiments, a piece of human DNA remained intact after being mixed with the polymer, suggesting that any genetic material found after processing a print could still be analyzed to further identify a suspect, the researchers say.  

The authors acknowledge funding from Yao Liu, academician of the Chinese Academy of Engineering; the Major Basic Research Project of the Natural Science Foundation of the Jiangsu Higher Education Institutions of China; the Priority Academic Program Development of Jiangsu Higher Education Institutions; and the National Key Technologies R&D Program of China.

“Highly Stable, Nondestructive, and Simple Visualization of Latent Blood Fingerprints Based on Covalent Bonding Between the Fluorescent Conjugated Polymer and Proteins in Blood”
ACS Applied Materials & Interfaces

Featured image: Fingerprint patterns made in blood are clearly visible on aluminum foil (left) and painted wood (right) when developed with a fluorescent polymer.Credit: Adapted from ACS Applied Materials & Interfaces 2021, DOI: 10.1021/acsami.1c00710


Provided by American Chemical Society

Detailing The Formation of Distant Solar Systems With NASA’s Webb Telescope (Astronomy)

We live in a mature solar system—eight planets and several dwarf planets (like Pluto) have formed, the latter within the rock- and debris-filled region known as the Kuiper Belt. If we could turn back time, what would we see as our solar system formed? While we can’t answer this question directly, researchers can study other systems that are actively forming—along with the mix of gas and dust that encircles their still-forming stars—to learn about this process.

Still-forming solar systems, known as planet-forming disks, come in a variety of shapes and sizes—and some show that bodies like forming planets may be clearing paths as they orbit the central stars. A research team led by Thomas Henning of the Max Planck Institute for Astronomy in Heidelberg, Germany, will survey more than 50 targets, including TW Hydrae (left), HD 135344B (center), and 2MASS J16281370 (right) using NASA’s James Webb Space Telescope. The observatory’s capabilities in infrared light and its high-resolution data will allow them to very precisely model which elements and molecules are present, adding to our understanding of the makeup of these planet-forming disks. Credit: NASA, ESA, ESO, STScI, S. Andrews (Harvard-Smithsonian CfA), B. Saxton (NRAO/AUI/NSF), ALMA (ESO/NAOJ/NRAO), T. Stolker et al.

A team led by Dr. Thomas Henning of the Max Planck Institute for Astronomy in Heidelberg, Germany, will employ NASA’s upcoming James Webb Space Telescope to survey more than 50 planet-forming disks in various stages of growth to determine which molecules are present and ideally pinpoint similarities, helping to shape what we know about how solar systems assemble.

Their research with Webb will specifically focus on the inner disks of relatively nearby, forming systems. Although information about these regions has been obtained by previous telescopes, none match Webb’s sensitivity, which means many more details will pour in for the first time. Plus, Webb’s space-based location about a million miles (1.5 million kilometers) from Earth will give it an unobstructed view of its targets. “Webb will provide unique data that we can’t get any other way,” said Inga Kamp of the Kapteyn Astronomical Institute of the University of Groningen in the Netherlands. “Its observations will provide molecular inventories of the inner disks of these solar systems.”

This research program will primarily gather data in the form of spectra. Spectra are like rainbows—they spread out light into its component wavelengths to reveal high-resolution information about the temperatures, speeds, and compositions of the gas and dust. This incredibly rich information will allow the researchers to construct far more detailed models of what is present in the inner disks—and where. “If you apply a model to these spectra, you can find out where molecules are located and what their temperatures are,” Henning explained.

These observations will be incredibly valuable in helping the researchers pinpoint similarities and differences among these planet-forming disks, which are also known as protoplanetary disks. “What can we learn from spectroscopy that we can’t learn from imaging? Everything!” Ewine van Dishoeck of Leiden University in the Netherlands exclaimed. “One spectrum is worth a thousand images.”

This infographic is an simplified artistic representation of planet formation, following the format of a baking recipe. Credit: L. Hustak (STScI)

A “Mountain” of New Data

Researchers have long studied protoplanetary disks in a variety of wavelengths of light, from radio to near-infrared. Some of the team’s existing data are from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, which collects radio light. ALMA excels at constructing images of the outer disks. If you were to compare the span of their outer disks to the size of our Solar System, this region is past Saturn’s orbit. Webb’s data will complete the picture by helping researchers model the inner disks.

Some data already exist about these inner disks—NASA’s retired Spitzer Space Telescope served as a pathfinder—but Webb’s sensitivity and resolution are required to identify the precise quantities of each molecule as well as the elemental compositions of the gas with its data, known as spectra. “What used to be a very blurry peak in the spectrum will consist of hundreds if not thousands of detailed spectral lines,” van Dishoeck said.

Webb’s specialty in mid-infrared light is particularly important. It will enable researchers to identify the “fingerprints” of molecules like water, carbon dioxide, methane, and ammonia—which can’t be identified with any other existing instruments. The observatory will also determine how starlight impacts the chemistry and physical structures of the disks.

Protoplanetary disks are complex systems. As they form, their mix of gas and dust is distributed into rings across the system. Their materials travel from the outer disk to the inner disk—but how? “The inner portion of the disk is a very dynamic place,” explains Tom Ray of the Dublin Institute for Advanced Studies in Ireland. “It’s not only where terrestrial-type planets form, but it’s also where supersonic jets are launched by the star.”

Video: Solar systems take millions of years to form. They start out as globs of gas and dust that orbit a central star, which itself may also be forming. Gravity and other forces cause material within the disk to collide. If the collision is gentle enough, the material fuses, growing like rolling snowballs. Over time, dust particles combine to form pebbles, which evolve into mile-sized rocks. As these forming planets orbit their star, they clear material from their path, leaving tracks of largely empty space. At the same time, the star gobbles up nearby gas and pushes more distant material farther away. Watch the video to see this process unfold. Credit: NASA’s Goddard Space Flight Center; NASA/JPL-Caltech

Jets emitted by the star lead to a mixing of elements in the inner and outer disks, both by sending out particles and permitting other particles to move inward. “We think that as material leaves, it loses its spin, or angular momentum, and that this allows other material to move inward,” Ray continued. “These exchanges of material will obviously impact the chemistry of the inner disk, which we’re excited to explore with Webb.”

Exciting Insights Await

PDS 70 is farther at 370 light-years away. It also has a large gap in its inner ring, plus data have revealed that two forming planets, known as protoplanets, are present and gathering material. “Webb’s mid-infrared measurements will help us refine what we know about them, as well as the material around them,” Kamp explained.

With dozens of targets on their list, it’s difficult for team members to play favorites. “I love them all,” Henning said. “One question I’d like to answer concerns the connection between the composition of planet-forming disks and the planets themselves. With Webb, we will observe far more detail about which types of material are available for a potential planet to accrete.”

After refining the data, his team will apply the discrete data points to models. “This will allow us to do a graphic reconstruction of these systems,” he continued. These models will be shared with the astronomical community, enabling other scientists to examine the data, and make their own projections or glean new findings. These studies will be conducted through a Guaranteed Time Observations (GTO) program.

Provided by NASA

Fingerprints Moisture-regulating Mechanism Strengthens Human Touch (Biology)

Human fingerprints have a self-regulating moisture mechanism that not only helps us to avoid dropping our smartphone, but could help scientists to develop better prosthetic limbs, robotic equipment and virtual reality environments, a new study reveals.

Fingerprints’ moisture mechanism could be boon to robotics experts © University of Birmingham

Primates – including humans, monkeys and apes – have evolved epidermal ridges on their hands and feet with a higher density of sweat glands than elsewhere on their bodies. This allows precise regulation of skin moisture to give greater levels of grip when manipulating objects.

Fingerprints help to increase friction when in contact with smooth surfaces, boost grip on rough surfaces and enhance tactile sensitivity. Their moisture-regulating mechanism ensures the best possible hydration of the skin’s keratin layer to maximise friction.

Researchers at the University of Birmingham worked with partners at research institutions in South Korea, including Seoul National University and Yonsei University – publishing their findings today in Proceedings of the National Academy of Sciences (PNAS).

Co-author Mike Adams, Professor in Product Engineering and Manufacturing, at the University of Birmingham commented: “Primates have evolved epidermal ridges on their hands and feet. During contact with solid objects, fingerprint ridges are important for grip and precision manipulation. They regulate moisture levels from external sources or the sweat pores so that friction is maximised and we avoid ‘catastrophic’ slip and keep hold of that smartphone.”

“Understanding the influence of finger pad friction will help us to develop more realistic tactile sensors – for example, applications in robotics and prosthetics and haptic feedback systems for touch screens and virtual reality environments.”

Ultrasonic lubrication is commonly used in touch screen displays that provide sensory ‘haptic’ feedback, but its effectiveness is reduced when a user has dry compared with moist finger pads. Moreover, being able to distinguish between fine-textured surfaces, such as textiles, by touch relies on the induced lateral vibrations but the absence of sliding friction inhibits our ability to identify what we are actually touching.

Fingerprints are unique to primates and koalas – appearing to have the dual function of enhancing evaporation of excess moisture whist providing a reservoir of moisture at their bases that enables grip to be maximised.

The researchers have discovered that, when finger pads are in contact with impermeable surfaces, the sweat from pores in the ridges makes the skin softer and thus dramatically increases friction. However, the resulting increase in the compliance of the ridges causes the sweat pores eventually to become blocked and hence prevents excessive moisture that would reduce our ability to grip objects.

Using hi-tech laser-based imaging technology, the scientists found that moisture regulation could be explained by the combination of this sweat pore blocking and the accelerated evaporation of excessive moisture from external wetting as a result of the specific cross-sectional shape of the epidermal furrows when in contact with an object.

These two functions result in maintaining the optimum amount of moisture in the fingerprint ridges that maximises friction whether the finger pad is initially wet or dry.

“This dual-mechanism for managing moisture has provided primates with an evolutionary advantage in dry and wet conditions – giving them manipulative and locomotive abilities not available to other animals, such as bears and big cats,” added Professor Adams.

Reference: Seoung-Mok Yum, In-Keun Baek, Dongpyo Hong, Juhan Kim, Kyunghoon Jung, Seontae Kim, Kihoon Eom, Jeongmin Jang, Seonmyeong Kim, Matlabjon Sattorov, Min-Geol Lee, Sungwan Kim, Michael J. Adams, Gun-Sik Park, “Fingerprint ridges allow primates to regulate grip”, Proceedings of the National Academy of Sciences Nov 2020, 202001055; DOI: 10.1073/pnas.2001055117 https://www.pnas.org/content/early/2020/11/24/2001055117

Provided by University of Birmingham

Notes to editors:

* The University of Birmingham is ranked amongst the world’s top 100 institutions. Its work brings people from across the world to Birmingham, including researchers, teachers and more than 6,500 international students from over 150 countries.
* ‘Fingerprint ridges allow primates to regulate grip’ – Seoung-Mok Yum, In-Keun Baek, Dongpyo Hong, Juhan Kim, Kyunghoon Jung, Seontae Kim, Kihoon Eom, Jeongmin Jang, Seonmyeong Kim, Matlabjon Sattorov, Min-Geol Leed, Sungwan Kime, Michael J. Adams and Gun-Sik Parka is published in Proceedings of the National Academy of Sciences (PNAS)

Social Bacteria build Shelters using the Physics of Fingerprints (Biology)

The rod-shaped microbes cooperate to construct structures called fruiting bodies when famine strikes; a new study explores the first steps in this process

Forest-dwelling bacteria known for forming slimy swarms that prey on other microbes can also cooperate to construct mushroom-like survival shelters known as fruiting bodies when food is scarce. Now a team at Princeton University has discovered the physics behind how these rod-shaped bacteria, which align in patterns like those on fingerprint whorls and liquid crystal displays, build the layers of these fruiting bodies. The study was published in Nature Physics.

When food is scarce, members of a species of forest-dwelling bacteria come together to build structures called fruiting bodies to survive until food becomes more available. Princeton researchers have identified how these bacteria harness the same physical laws that lead to the whorls of a fingerprint to build the structures, which consist of the bacterial cells themselves and secretions that glue the edifice together. The structures are about a tenth of a millimeter high, or tens to hundreds of times taller than a single bacterial cell. On the human scale, this size compares to the height of a skyscraper. Image credit: Cassidy Yang, Princeton University

“In some ways, these bacteria are teaching us new kinds of physics,” said Joshua Shaevitz, professor of physics and the Lewis-Sigler Institute for Integrative Genomics. “These questions exist at the intersection of physics and biology. And you need to understand both to understand these organisms.”

Myxococcus xanthus, or Myxo for short, is a bacterial species capable of surprisingly cooperative behaviors. For example, large numbers of Myxo cells come together to hunt other bacteria by swarming toward their prey in a single undulating mass.

When food is scarce, however, the rod-like cells stack atop one another to form squishy growths called fruiting bodies, which are hideaways in which some of the Myxo cells transform into spores capable of rebooting the population when fresh nutrients arrive. But until now, scientists haven’t understood how the rods acquire the ability to begin climbing on top of each other to build the droplet-like structures.

To find out more about how these bacteria behave, the researchers set up a microscope capable of tracking Myxo’s actions in three dimensions. The scientists recorded videos of the rod-shaped microbes, which pack closely together like stampeding wildebeest, rushing across the microscope dish in swaths that swirl around each other, forming fingerprint-like patterns.

When two swaths meet, the researchers observed, the point of intersection was exactly where the new layer of cells started to form. The bacteria started to pile up and created a situation where the only direction to go was up.

A high-resolution image of rod-shaped Myxococcus xanthus bacterial cells, with colors indicating the direction of cell alignment. ©Katherine Copenhagen, Princeton University

“We found that these bacteria are exploiting particular points of the cell alignment where stresses build that enable the colony to construct new cell layers, one on top of the other,” said Ricard Alert, a postdoctoral research fellow in the Princeton Center for Theoretical Science and one of the study’s co-first authors. “And that’s ultimately how this colony responds to starvation.”

Researchers call the points where the massing cells collide “topological defects,” a term that refers to the mathematics that describe these singular points. Topology is the branch of mathematics that finds similarities between objects such as teacups and donuts, because one can be stretched or deformed into the other.

“We call these points topological because if you want to get rid of a single one of these defects, you cannot do it by a smooth transformation – you cannot just perturb the alignment of the cells to get rid of that point where alignment is lost,” Alert said. “Topology is about what you can and cannot do via smooth transformations in mathematics.”

Myxo bacterial cells behave much like liquid crystals, the fluids found in smartphone screens, which are made of rod-shaped molecules. Unlike passive liquid crystals, however, Myxo rods are alive and can crawl. The bacteria most likely have evolved to take advantage of both passive and active factors to build the fruiting bodies, the researchers said.

Katherine Copenhagen, associate research scholar in the Lewis-Sigler Institute, and a co-first author on the study, took videos of the cells under the microscope and analyzed the results. She said that at first the team was not sure what they were looking at.

“We were trying to study layer formation in bacteria to find out how these cells build these droplets, and we had just gotten a new microscope, so I put a sample of the bacteria from another project that had nothing to do with layer formation under the microscope and imaged it for a few hours,” Copenhagen said. “The next time our group got together, I said ‘I have this video, so let’s take a look at it.’ And we were mesmerized by what we saw.”

The combination of physics and biology training among the researchers enabled them to recognize new theoretical insights into how the vertical layers form. “It says something about the value of the collaborative culture at Princeton,” said Ned Wingreen, the Howard A. Prior Professor in the Life Sciences, professor of molecular biology and the Lewis-Sigler Institute. “We chat with each other and share crazy ideas and show interesting data to each other.”

“A moment that I remember quite vividly,” Alert said, “is watching these videos at the very beginning of this project and starting to realize, wait, do layers form exactly where the topological defects are? Could it be true?” To explore the results, he followed up the studies by confirming them with numerical and analytical calculations.

“The initial realization that came just by watching these movies, that was a cool moment,” he said.

References: Copenhagen, K., Alert, R., Wingreen, N.S. et al. Topological defects promote layer formation in Myxococcus xanthus colonies. Nat. Phys. (2020). https://doi.org/10.1038/s41567-020-01056-4

Provided by Princeton University

Memories Create ‘Fingerprints’ That Reveal How the Brain is Organized (Neuroscience)

While the broad architecture and organization of the human brain is universal, new research shows how the differences between how people reimagine common scenarios can be observed in brain activity and quantified. These unique neurological signatures could ultimately be used to understand, study, and even improve treatment of disorders such as Alzheimer’s disease.

“When people imagine similar types of events, each person does it differently because they have different experiences,” said Feng (Vankee) Lin, Ph.D., R.N. “Our research demonstrates that we can decode the complex information in the human brain related to everyday life and identify neural ‘fingerprints’ that are unique to each individual’s remembered experience.” Lin is an associate professor in the University of Rochester Del Monte Institute for Neuroscience and co-author of the study which appears in the journal Nature Communications.

In the study, researchers asked 26 participants to recall common scenarios, such as driving, attending a wedding, or eating out at a restaurant. The scenarios were broad enough so that each participant would reimagine them differently. For example, when researchers asked volunteers to vividly remember and describe an occasion involving dancing, one person might recall watching their daughter participating in a dance recital, while another may imaging themselves dancing at a Bar Mitzvah.

The participant’s verbal descriptions were mapped to a computational linguistic model that approximates the meaning of the words and creates numerical representation of the context of the description. They were also asked to rate aspects of the remembered experience, such as how strongly it was associated with sound, color, movement, and different emotions.

The study volunteers were then placed in a functional MRI (fMRI) and asked to reimagine the experience while researchers measured which areas of the brain were activated. Using the fMRI data and the subject’s verbal descriptions and ratings, researchers were able to isolate brain activity patterns associated with that individual’s experiences. For instance, if the participant imagined driving through a red light in the scenario, areas of the brain associated with recalling motion and color would be activated. Using this data, the researchers built a functional model of each participant’s brain, essentially creating a unique signature of their neurological activity.

The researchers were able to identify several areas of the brain that served as hubs for processing information across brain networks that contribute to recalling information about people, objects, places, emotions, and sensations. The team was also able to observe how activation patterns within these networks differed on an individual level depending upon the details of each person’s recollections and imagination.

“One of the goals of cognitive science is to understand how memories are represented and manipulated by the human brain,” said Andrew Anderson, Ph.D., with the Del Monte Institute for Neuroscience and co-author of the study. “This study shows that fMRI can measure brain activity with sufficient signal to identify meaningful interpersonal differences in the neural representation of complex imagined events that reflect each individual’s unique experience.”

In addition to expanding our understanding of how the brain is networked, the authors point out that many of the key regions they identified tend to decline in function as we age and are vulnerable to the degeneration that occurs in disease like Alzheimer’s. The findings could lead to new ways to diagnose and study disorders associated with irregular memory deficits, including dementia, schizophrenia, and depression, and perhaps even personalize treatments and predict which therapies will be more effective.

Additional co-authors include Kelsey McDermott, Brian Rooks, Kathi Heffner, and David Dodell-Feder with the University of Rochester. The study was funded with support from the National Center for Advancing Translational Sciences of the National Institutes of Health and the URMC Clinical the Translational Science Institute.

Provided by University of Rochester Medical Center