Energy flow in semiconductors: new insights thanks to ultrafast spectroscopy

It took three years for researchers Grazia Raciti, Begoña Abad Mayor, and Ilaria Zardo (from left to right) to develop and characterize the complex setup – only then were the now-published measurements possible.
Photo Credit: C. Möller, Swiss Nanoscience Institute, University of Basel

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Researchers achieved unprecedented accuracy in observing energy flow mechanisms within the semiconductor germanium, detailing step-by-step energy transfer from the electronic system to the atomic lattice following ultrafast excitation.
• Methodology: The team utilized a novel combination of time-resolved Raman spectroscopy to measure lattice vibration changes and transient reflection spectroscopy to record light behavior, stimulating the material with 30-femtosecond laser pulses and validating results with computer simulations.
• Key Data: The experimental setup detected intensity changes of less than 1 percent and frequency shifts under 0.2 cm⁻¹ with a temporal resolution capable of distinguishing picosecond-scale responses from microsecond-interval pulses.
• Significance: This study provides a comprehensive understanding of how energy dissipates and converts to heat in semiconductors, addressing critical challenges regarding overheating and efficiency in modern electronics.
• Future Application: Findings will directly inform the design of next-generation computer chips, sensors, and phononic components that offer faster recovery times and reduced thermal accumulation.
• Branch of Science: Condensed Matter Physics and Nanoscience.
• Additional Detail: The specific combination of spectroscopic methods allowed for the simultaneous observation of frequency, intensity, and duration of lattice vibrations (phonons) as they evolved over time.

Honey Bees (Apis mellifera): The Metazoa Explorer

Photo Credit: Sarah Damen

Taxonomic Definition

Apis mellifera, commonly referred to as the Western honey bee, is a eusocial insect belonging to the family Apidae and the order Hymenoptera. Originally native to Europe, Africa, and Western Asia, the species has achieved a near-global distribution due to anthropogenic domestication for pollination services and honey production. It is the type species of the genus Apis and is distinguished by strict caste differentiation and perennial colony structures.

Octopus (Octopoda): The Metazoa Explorer

Photo Credit: Diane Picchiottino

Taxonomic Definition

The Octopoda is an order of soft-bodied, eight-limbed mollusks within the class Cephalopoda. Characterized by bilateral symmetry, a ganglionic nervous system, and the complete reduction of the internal shell (gladius), members of this order occupy a ubiquitous range across the global ocean, extending from intertidal coral reefs to abyssal hydrothermal vents. They are taxonomically distinct from Decapodiformes (squids and cuttlefish) by their lack of feeding tentacles and specific arm morphology.

Aardvark (Orycteropus afer): The Metazoa Explorer

Aardvark (Orycteropus afer)
Image Credit: Scientific Frontline / stock image

Taxonomic Definition

The Aardvark (Orycteropus afer) is the sole extant species of the order Tubulidentata and family Orycteropodidae, representing a distinct phylogenetic lineage within the superorder Afrotheria. Endemic to sub-Saharan Africa, its geographical range encompasses savanna, grassland, and semi-arid bushland, excluding only the true deserts (Sahara, Namib) and dense equatorial rainforests where soil composition prevents fossorial activity. It is characterized as a nocturnal, myrmecophagous (ant and termite-eating) mammal with unique dental morphology that defines its taxonomic order.

Glass sponges (Hexactinellida): The Metazoa Explorer

Euplectella aspergillum
Photo Credit: National Oceanic and Atmospheric Administration

Taxonomic Definition

The Hexactinellida, commonly known as glass sponges, constitute a class within the phylum Porifera characterized by a skeleton composed of siliceous spicules typically exhibiting triaxon (six-rayed) symmetry. Exclusively marine and predominantly deep-sea organisms, they are found globally at depths ranging from 200 to over 6,000 meters, with significant concentrations in the Antarctic and North Pacific waters. Unlike other sponges, their soft tissue consists largely of a syncytium, a continuous multinucleated cytoplasm, rather than discrete cellular units.

Koala (Phascolarctos cinereus): The Metazoa Explorer

Photo Credit: David Clode

Taxonomic Definition

The Koala (Phascolarctos cinereus) is an arboreal herbivorous marsupial native to Australia and the sole extant representative of the family Phascolarctidae. Taxonomically situated within the order Diprotodontia, it is most closely related to the Vombatidae (wombats). Its range extends along the eastern and southern distincts of Australia, spanning Queensland, New South Wales, Victoria, and South Australia, characterized by a dependence on sclerophyll forests dominated by the genus Eucalyptus.

Tigers (Panthera tigris): The Metazoa Explorer

Taxonomic Definition

Panthera tigris constitutes the largest extant species within the family Felidae and the genus Panthera. Taxonomically situated within the Order Carnivora, this obligate carnivore is historically distributed across much of Asia, ranging from the temperate forests of the Russian Far East to the tropical mangroves of the Sundarbans and the rainforests of Sumatra. It is defined by its distinct dark vertical stripes on orange-brown fur with a lighter underside, a phenotype resulting from specific expression of the Agouti and Tabby signaling pathways.

Herons (Ardeidae) : The Metazoa Explorer

Photo Credit: Gerhard Crous

Taxonomic Definition

The Ardeidae are a cosmopolitan family of wading birds within the order Pelecaniformes, comprising herons, egrets, and bitterns. This clade is characterized by long legs, elongated necks, and a distinctive spearing feeding mechanism, inhabiting a vast array of freshwater, brackish, and coastal wetland ecosystems globally, with the exception of the poles and extreme deserts. Recent molecular phylogenetic studies have firmly placed Ardeidae within Pelecaniformes, distinct from the Ciconiiformes (storks) with which they were historically grouped.

What Is: Invasive Species

Image Credit: Scientific Frontline / stock image

Scientific Frontline: Extended "At a Glance" Summary

The Core Concept: Invasive species are non-native organisms that, upon introduction to a new environment, escape the evolutionary checks of their native ranges to cause significant ecological, economic, or human health harm. This phenomenon represents a systemic disruption of biophysical systems rather than merely the presence of an unwanted plant or animal.

Key Distinction/Mechanism: The defining characteristic separating "invasive" from "non-native" is impact; while many non-native species (like agricultural crops) are beneficial, invasive species actively dismantle native ecosystems. They often succeed via the Enemy Release Hypothesis, flourishing because they have left behind natural predators and diseases, or through Priority Effects, such as leafing out earlier than native flora to monopolize resources.

Origin/History: While natural translocation has occurred for eons, the current crisis is driven by the "relentless engine of human globalization" in the Anthropocene. The concept is underscored by the "Ten Percent Rule," a statistical filter noting that roughly 10% of transported species survive, 10% of those establish, and 10% of those become destructive invaders.

Scientists develop molecules that may treat Crohn’s disease

Broad scientists designed molecules (pictured in teal) that can bind CARD9 (white with red and blue), a protein linked to inflammatory bowel disease.
Image Credit: Rush et al. Cell. DOI: 10.1016/j.cell.2025.12.013

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Researchers developed small-molecule drug candidates that mimic a rare, protective variant of the CARD9 gene to treat Crohn's disease and other inflammatory bowel diseases.
• Methodology: The team utilized a "binder-first" strategy, screening 20 billion molecules to identify binders to the CARD9 coiled-coil domain, followed by X-ray crystallography and competitive binding assays to isolate compounds that block inflammatory signaling.
• Key Data: The initial library screen evaluated over 20 billion compounds, ultimately yielding molecules that significantly reduced inflammation in both human immune cells and a mouse model expressing the human CARD9 gene.
• Significance: This work validates a complete "genetics-to-therapeutics" pipeline, proving that scaffolding proteins previously considered "undruggable" can be effectively targeted by mimicking naturally occurring protective variants.
• Future Application: Immediate efforts focus on optimizing these compounds for human clinical trials, while the broader methodology provides a blueprint for developing drugs against other difficult genetic targets.
• Branch of Science: Chemical Biology, Immunology, Genetics, and Molecular Biology.
• Additional Detail: The development strategy parallels the success of PCSK9 inhibitors for cholesterol, leveraging the safety profile of a natural genetic variant to guide drug design.