Weekly Advanced Technologies〔70〕| The World's First "Matter Spectrum Chip" Debuts; Science Behind "Stopping Eating at Seven-tenths Satiety Helps You Live Longer."

As an important basic module in the era of artificial intelligence, the sensing-computing integrated chip can endow a series of miniaturized and portable terminal devices such as mobile phones, robots, and drones with powerful sensing and computing capabilities. The research group led by Cui Kaiyu from the team of HUANG Yidong at the Department of Electronic Engineering, Tsinghua University, has developed the world's first "matter spectrum chip" - Spectral Imaging Chip 2.0. This chip has achieved a new type of sensing-computing integrated edge computing for "matter imaging", inaugurating a new paradigm of the Spectral Convolutional Neural Network (SCNN) Chip that goes beyond the capabilities of the human eye.

As an old saying goes, to enjoy a long life, stop eating when you're seven-tenths satiated. But do you know the science behind this? The research team led by LIN Shengcai at Xiamen University discovered a calorie restriction mimetic-lithocholic acid, and deciphered the specific mechanism by which it exerts its life-extending effect, providing new theories and targets for the development of new longevity drugs.

Based on the weekly diary of technology provided by the daily list of the NCSTI online service platform, we launch the column "Weekly Advanced Technologies" at the hotlist of sci-tech innovation. Today, let's check out No.70.

1. Nature Communications丨The World's First "Matter Spectrum Chip" Debuts

SCNN-based matter spectral chips implemented using optical hypersurfaces and pigments, respectively

Computing power serves as the most crucial cornerstone and driving force in the intelligent era. Meanwhile, vision is the primary means for both humans and machines to perceive the world. As a vital basic module in the age of artificial intelligence, the "sensing-computing integrated chip" endows a range of miniaturized and portable terminal devices, including mobile phones, robots, and drones, with formidable perception and computing capabilities.

The research group led by CUI Kaiyu from HUANG Yidong's team at the Department of Electronics, Tsinghua University, introduced the world's first "matter spectrum chip" - Spectral Imaging Chip 2.0, namely the Matter Imaging Spectral Convolutional Neural Network Chip (SCNN). This chip is designed for the complex visual tasks of sensing-computing integrated chips. Moreover, it is the first to utilize natural light containing the spectral information of matter. It is also the first optical computing chip that can directly employ natural light with material spectral information as input. This breakthrough has overcome the bottleneck that most existing optical neural networks face in practical applications, enabling the execution of complex visual computing tasks in the real world.

In this research, optical hypersurfaces and pigments were employed as spectral modulation structures to fabricate two distinct object spectral chips, aiming to validate the feasibility of the spectral convolutional neural network framework.

Specifically, the hypersurface-based chip exhibits superior spectral modulation capabilities and holds the potential for full optical field sensing, covering aspects such as polarization, phase, and incident angle. On the other hand, the pigment-based chip has successfully reached 12-inch wafer mass production. It features higher integration levels and lower processing and preparation costs.

The research team believes that the spectral convolutional neural network solution has the following three advantages:

(1) The optical computing convolutional layer implemented based on image sensors features a high degree of integration and low power consumption. Moreover, it can directly sense natural light (broadband incoherent light containing two spatial dimensions and one spectral dimension) without relying on coherent light sources. 

(2) The optical computing convolutional layer combines sensing and computing. That is, while the image sensor is taking pictures, the computing is also completed. This enables the acquisition and processing of high-dimensional spectral images on edge devices and mobile terminals with limited computing power, achieving "Matter meta-imaging" and making it easy to popularize the application of spectral imaging to the terminal level. 

(3) The optoelectronic hybrid computing architecture can take into account the advantages of optical computing, such as high speed, parallel processing, and low power consumption, as well as the flexibility of electrical computing. By making full use of the image sensor, which is currently the optoelectronic detection array chip with the highest degree of integration, each pixel of cameras with millions or even hundreds of millions of pixels can perform calculations.

The Matter Spectrum chip has the remarkable ability to directly process natural images. It can execute highly parallel inner product operations across the spatial dimension of millions to billions of pixels. By incorporating a continuous spectral dimension, it can perceive the material information embedded within natural images. This involves dynamically identifying the components of matter and mapping them into the feature space, thereby achieving a new matter meta-imaging (MMI) sensing-computing integrated edge computing model. This breakthrough unlocks a new function of MMI that extends beyond the capabilities of the human eye.

Specifically, through the introduction of the continuous spectral dimension, the chip can detect the material information in natural images. That is, it can dynamically identify material components and map them to the feature space. As a result, a novel 'matter imaging' sensing-computing-integrated edge computing system is realized. This endows the end devices of machine vision and edge computing with the new functionality of matter-imaging, thus inaugurating a new paradigm for the MMI neural network chip that goes beyond the limitations of human vision.

2. Nature丨Science Behind "Stopping Eating at Seven-tenths Satiety Helps You Live Longer."

Lysosomal pathway panorama

As an old saying goes, to enjoy a long life, stop eating when you're seven-tenths satiated. The concept of "seven-tenths satiety" is closely associated with calorie restriction (CR). CR is a well-known approach in the realm of aging research, renowned for its ability to extend lifespan and decelerate the aging process. This dietary strategy involves reducing food intake to approximately 70% of normal levels while ensuring that no nutritional deficiencies occur.

The remarkable power of calorie restriction lies in the fact that it is the sole method thus far where anti-aging effects have been consistently witnessed across all experimental animal species studied. These include yeast, nematodes, fruit flies, mice, and primates.

In recent years, both retrospective and experimental studies involving human populations have also shown that calorie restriction can mitigate the complications associated with aging - related conditions such as obesity, insulin resistance, muscle degradation, dyslipidemia, and cancer. Significantly, this can be achieved without compromising the quality of life of the subjects involved.

However, notwithstanding the extensive advantages of calorie restriction, implementing long-term dietary control on a population scale proves to be a challenging feat. This is particularly true among the elderly, who are in great need of decelerating the aging process. In this age group, dietary restriction might even give rise to issues such as malnutrition and muscle atrophy.

Therefore, delving into the bright side of calorie restriction, specifically its precise mechanism for delaying aging, and on this foundation, mimicking calorie restriction to ultimately enable people to achieve life extension without the need for dietary control has become the aspiration of the medical community. At present, there are numerous drugs that imitate calorie restriction, such as metformin, resveratrol, and rapamycin. Their common characteristic is to target the key action proteins and the downstream pathways of calorie restriction, thereby attaining the goal of extending lifespan.

Nonetheless, during actual calorie restriction, the changes that occur within the organism, the signals generated by these changes, and how these signals are transmitted to the aforementioned pathways to exert anti-aging effects remain incompletely understood. This situation presents significant challenges to our further design of relevant intervention strategies.

Beginning with serum-related experiments on calorie-restricted mice, the research team led by LIN Shengcai from Xiamen University conducted metabolomics identification and meticulous, case-by-case inspections. Eventually, they identified lithocholic acid (LCA), a mimic of calorie restriction. Subsequently, they verified the function of lithocholic acid in slowing down the aging process and extending the lifespan in nematodes, Drosophila, and mice respectively.

Building upon this foundation, they delved deeper into the matter. After further exploration, they finally pinpointed the molecular target of lithocholic acid - TULP3. They also discovered that TULP3 can delay the aging process. It does so by activating the sirtuin-v-ATPase signalling axis and triggering the activation of the AMPK protein, which is crucial in calorie restriction. In this way, TULP3 effectively delays the aging process.

Academician Lin offered an engaging account of the discovery process behind this achievement. He believes that the lysosomal pathway of AMPK exists inherently in higher organisms. Given its significant physiological function, it is highly probable that this pathway has been conserved throughout the process of evolution. The ability to not only endure hunger but also gain advantages from it serves as a form of “empowerment” bestowed upon life by nature.

3. Physical Review Letters丨They Create A Unique "Rainbow" Wonder in the Laboratory

Schematic diagram of a rainbow effect of the Landau zeroth modes induced by the synergistic effect of a pseudomagnetic field (PMF) and a pseudoelectric field (PEF). Landau zeroth modes with different frequencies are separated and localized to different spatial positions.

Gauge fields play a crucial role in studying the complex behavior of particles within systems like condensed matter physics, optics, acoustics, and cold atoms. Constructing a pseudomagnetic field (PMF), also known as an artificial gauge field, is a key approach to achieving Landau energy levels in optical systems.

In recent years, the question of how to create a PMF for uncharged systems has piqued the curiosity of researchers. The Landau energy levels of various uncharged systems have been gradually achieved through methods such as applying stress to graphene, fabricating gradient metamaterials, or using lattice - deformed optical waveguides. Consequently, research in this area has centered on the realization of Landau energy levels in uncharged systems.

Nevertheless, the Landau energy levels induced by PMFs consist of a series of nearly flat bands. In particular, for the zeroth modes, their high degree of degeneracy makes it challenging to distinguish between the modes. Physically, there is a dearth of effective means to explore the multiplexing of Landau modes.

Recently, LU cuicui's research team at the School of Physics, Beijing Institute of Technology (BIT), in collaboration with ZHANG Shuang at the University of Hong Kong, proposed to introduce both PMF and PEF simultaneously. The introduction of PMF is aimed at generating a series of Landau energy levels, while the introduction of PEF serves to break the degeneracy of the Landau energy levels.

Under the synergistic effect of these two artificial gauge fields, Landau modes with different frequencies on the same Landau energy level are spatially separated to different positions, presenting a unique rainbow-like confinement effect, which they named the “Landau rainbow”.

They prepared dielectric photonic crystals and characterized the distribution of electric field modes at different frequencies on the sample surface using a near-field detection system in the microwave band. The zero modes of Landau at different frequencies are clearly localized at different positions. Their experimental measurements are in good agreement with the simulation calculations.

The Landau levels exhibit a high level of degeneracy and a large number of diverse modes. Landau rainbow devices feature advantages like broadband nature and expandability. Owing to the topological features of Landau levels, Landau rainbow devices are highly robust. They can withstand the impacts of perturbations and impurities on energy bands to some extent. There is a promising prospect for their application in multi-wavelength optical information processing components, including topological slow-light devices, topological beam splitters, and topological wavelength division multiplexing systems. This research work creates a physical platform for the exploration of artificial gauge fields in photonics and presents strategies to facilitate the application of artificial gauge field physics in broadband information processing scenarios.

4. Advanced Science丨Who Decides Dopamine Regulation?

Frequency-dependent regulation of in vivo striatal dopamine secretion by GPCR-D2R

Dopamine plays a crucial role in the regulation of movement, motivation, learning, and the reward system. Dysregulation of dopamine homeostasis is closely linked to Parkinson's disease, schizophrenia, and addiction. Midbrain dopamine neurons release dopamine via both tonic and phasic firing modes. These modes act on G-protein-coupled receptors (GPCRs) to exert various physiological functions. 

Dopamine receptors are classified into two categories: type 1 and type 2, among which dopamine type 2 receptor (D2R) has both presynaptic and postsynaptic distributions. Presynaptic D2R is an autoinhibitory receptor, which can affect dopamine secretion by regulating the VGCC or GIRK channels through Gibg. In recent years, it has been found that GPCRs can sense voltage changes and thus regulate downstream signal transduction pathways. However, it remains unclear whether D2Rs can sense changes in the frequency or voltage of action potentials (APs) and regulate dopamine secretion under physiological conditions.

The research team led by WANG Changhe from the School of Life Science and Technology at Xi'an Jiaotong University collaborated with the team of ZHOU Zhuan from the College of Future Technology at Peking University. Their research has revealed that under physiological conditions, there exists a novel pathway for GPCR-D2R to regulate dopamine secretion. The frequency/voltage of action potentials directly acts on GPCR-D2R to modulate the function of downstream voltage-gated Ca2+ channels (VGCCs) , thereby regulating dopamine secretion. Among them, D131 is a voltage-sensitive site on D2R. The contribution of this new pathway to the regulation of dopamine secretion can be as high as 50%, indicating its significant physiological importance. This provides new theories and ideas for the regulation of synaptic transmission function by neuronal electrical activity and the treatment of related diseases.

5. Angew. Chem. Int. Ed.丨Setting New Records: Overcoming the Hurdles of Ultra-Narrowband Long-Wavelength Luminescent Materials

Photophysical properties of HBN molecules

For ultra-high-definition (UHD) display technology based on organic light-emitting diodes (UHD-OLEDs), the light-emitting materials need to have a high spectral width. Solving the technological bottleneck of spectral narrowing is crucial for meeting the industry display standard of wide colour gamut (BT.2020). Achieving this can significantly enhance the display effect of terminals. Over the past decade, narrowband multiple resonance thermally activated delayed fluorescence (MR-TADF) materials have made remarkable progress. They present a highly efficient solution for the material requirements of current display terminals.

Although most of the existing MR-TADF materials can achieve a certain degree of narrowband emission (full width at half maximum, FWHM < 50 nm), materials capable of achieving ultra-narrowband emission with an FWHM less than 20 nm are still rare. Moreover, these materials are almost limited to the blue to green light regions and it is difficult for them to cover the long wavelength range.

In addition, there is a lack of a high-performance molecular design framework in the field of ultra-narrowband long-wavelength luminescent materials. Therefore, how to simultaneously achieve spectral narrowing and red shift has become a core problem that needs to be urgently addressed in both academic and industrial circles.

Recently, the research group led by Zheng Youxuan from the School of Chemistry and Chemical Engineering at Nanjing University has made a significant breakthrough in the field of long-wavelength ultra-narrowband light-emitting materials. Through the precise incorporation of two boron atoms into a tetrazolane framework, they have innovatively designed a long-wavelength ultra-narrowband molecular structure, from which an ultra-narrowband yellow light-emitting material (HBN) was developed.

Experimental results demonstrate that the bis-boron embedding leads to a remarkable redshift of up to 165 nm in the emission spectrum compared to the tetrazolane precursor. Moreover, in a toluene dilute solution, HBN exhibits ultra-narrowband yellow light emission at 572 nm, with a spectral full width at half maximum (FWHM) of merely 17 nm. In n-hexane, the FWHM of the emission spectrum is further reduced to 12 nm, setting a new benchmark for the narrowest spectra in the mid- to long-wavelength range to date.

Their research has provided important guidance for the design of ultra-narrowband pure green to red light materials through the precise regulation of molecular architecture and material properties. It has also offered experimental and theoretical references for the realization of wide color gamut display technology.

Columnist: Li Xiaoxiao

Translator: Liu Kaiyuan