Search

Synaptic vesicle transport by motor proteins along microtubules is a crucially active process underlying neuronal communication. It is known that microtubules are destabilized by tau-hyperphosphorylation, which causes tau proteins to detach from microtubules and form neurofibril tangles. However, how tau-phosphorylation affects the transport dynamics of motor proteins on the microtubule remains unknown. Here, we discover that the long-distance unidirectional motion of vesicle-motor protein multiplexes (VMPMs) in living cells is suppressed under tau-hyperphosphorylation, with the consequent loss of fast vesicle-transport along the microtubule. The VMPMs in hyperphosphorylated cells exhibit seemingly bidirectional random motion, with dynamic properties far different from those of VMPM motion in normal cells. We establish a parsimonious physicochemical model of VMPM’s active motion that provides a unified, quantitative explanation and predictions for our experimental results. Our analysis reveals that, under hyperphosphorylation conditions, motor protein multiplexes have both static and dynamic motility fluctuations. The loss of fast vesicle-transport along the microtubule can be a mechanism of neurodegenerative disorders associated with tau-hyperphosphorylation.

On a hot summer night in July 2020, several technology education experts in South Korea and the United States gathered in a Zoom meeting room. The meeting started with a brief introduction of ITEEA's new standards, "Standards for Technological and Engineering Literacy" ("STEL"; ITEEA, 2020), to the Korean audience and discussed a plan to translate "STEL" into the Korean language. This was the starting point of the Korean "STEL" translation project. Nine months later, in April 2021, "STEL" was finally printed in Korean and released to the public. This article will narrate how "STEL" was translated into Korean and what implications the translation has for Korean educators.

The Cassie–Baxter state of wetting explains a large equilibrium contact angle and the slippery dynamics of a water droplet on a superhydrophobic rough surface. It also causes a contact angle hysteresis (CAH) that cannot be fully described by dynamic wetting theories including the molecular kinetic theory (MKT). We analyze the contact line dynamics on a superhydrophobic surface in the framework of the MKT. Multi-body dissipative particle dynamics simulations of a capillary bridge confined between two rough surfaces under steady shear are performed. We find that, in addition to the contact line friction force from the MKT, an additional friction force contribution is needed on rough surfaces. It can be obtained by subtracting from the total friction force the force solely caused by the actual liquid–solid contact area. We find that the additional force is almost constant at all contact line velocities. Thus, it is directly related to the CAH. The CAH originates not only from contact line pinning but also from the shear flow due to the strong friction in the central region of the liquid–solid interface away from the contact line. The analysis of the particle flow inside the capillary bridge shows that liquid particles trapped in the grooves of the surface texture actually move with the same velocity as the surface and exert strong additional friction to other liquid particles. This work extends the MKT to rough surfaces, as well as to elucidate the origin of the CAH of a capillary bridge. The finding would help to better understand other situations of dynamic wetting on superhydrophobic surfaces. [ABSTRACT FROM AUTHOR]

C60 is a nanomaterial produced from the pyrolysis of hydrocarbons that needs to be extracted and purified to obtain the desired properties. Previous studies reported purification as the environmental hotspot of the C60 production process. However, no study has evaluated existing C60 purification methods and proposed alternatives based on environmental, cost, and chemical hazards. Here we used life cycle assessment (LCA) and evaluated the most common existing C60 purification methods (chromatography-crystallization, crystallization, & complexation) and identified selective complexation with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the greenest existing C60 purification technique that has less environmental (70% from chromatography-crystallization & 50% from crystallization), cost (70% from chromatography-crystallization & 80% from crystallization), and chemical (30% from chromatography-crystallization & crystallization) hazards. The solvent (1,2,4-trymethylbenzene (TMB)) was identified as the environmental hotspot contributing to more than 95% of the cumulative energy demand (CED) of the complexation process. We employed green chemistry principles and an iterative approach to assess the performance of potential replacements (linseed oil, olive oil, toluene, & xylene) for TMB. Although we evaluated solvents that are expected to be greener than petroleum-based solvents, we determined toluene as the greenest alternative. Compared to the baseline complexation method, using toluene reduced the environmental impact by 59%, cost by 85%, and chemical hazards by 42%. Identifying toluene as the alternative green solvent for C60 purification can reduce the carbon footprint of C60-containing products used for various emerging applications, such as solar cells, hydrogen storage, biofuels, etc., which aligns with current decarbonization strategies. [ABSTRACT FROM AUTHOR]

The photon upconversion (UC) is the process that has been known for a long time. Especially, lanthanide-based UC materials recently have attracted huge interest of scientific community due to their narrow visible emission bands upon near-infrared (NIR) excitation. However, the excitation in the high excitation power of NIR can cause highly bright and broad emission (B-UC). Such explosive B-UC was distinct at high excitation condition with UC wavelength encompassing the entire visible range. Previously, the proposed model of B-UC origination includes heat, multi-photon absorption, and accumulated thermal energy transfer. In this article, we will show various experimental and theoretical evidence supporting the idea that B-UC arises from photophysical pathways. Here, the key experimental evidence for photophysical pathways model of B-UC is to measure B-UC in the low-temperature environment (22 K). In addition, the density functional theory was used to regenerate energy levels which would be compared to the absorption spectral bands in Er2O3. As a result, we are confident of an electron tunneling model from 2P3/2 of Er3+ to oxygen vacancy level (VO) of Er2O3. Then, VO electrons are sequentially excited to the conduction band of Er2O3 by energy transfer from 4F9/2 of Er3+. Finally, the electrons return to the VO of Er2O3 with concomitant B-UC. [ABSTRACT FROM AUTHOR]

Background and objectives: Telomere length is an indicator of biological aging, and it shortens during cell division. A short telomere length is associated with various age-related diseases and mortality. It is suggested that physical activity has a positive effect on the rate of telomere length shortening. Materials and Methods: Related studies, published in electronic databases, were searched with keywords, including exercise, telomere length, and randomized controlled trial. The data were weighted and pooled through a fixed-effect model. Results: Of the total 49 studies searched, 7 studies with 939 participants were considered suitable, and were analyzed qualitatively and quantitatively. Exercise is beneficial to telomere length. Aerobic exercise was effective as the type of exercise (MD, −0.03; 95% CI, −0.04 to −0.01). In addition, exercise for more than 6 months, with a change in lifestyle, is beneficial for telomere length (MD, −0.02; 95% CI, −0.04 to −0.01). Conclusions: The type and duration of exercise for positive improvement in telomere length is aerobic exercise for more than 6 months. [ABSTRACT FROM AUTHOR]