Study on the secondary structure and hydration effect of human serum albumin under acidic pH and ethanol perturbation with IR/NIR spectroscopy

Human serum albumin(HSA)is the most abundant protein in plasma and plays an essential physiological role in the human body.Ethanol precipitation is the most widely used way to obtain HSA,and pH and ethanol are crucial factors affecting the process.In this study,infrared(IR)spectroscopy and near-infrared(NIR)spectroscopy in combination with chemometrics were used to investigate the changes in the secondary structure and hydration of HSA at acidic pH(5.6-3.2)and isoelectric pH when ethanol concentration was varied from 0%to 40%as a perturbation.IR spectroscopy combined with the two-dimensional correlation spectroscopy(2DCOS)analysis for acid pH system proved that the secondary structure of HSA changed significantly when pH was around 4.5.What's more,the IR spectroscopy and 2DCOS analysis showed different secondary structure forms under different ethanol concentrations at the isoelectric pH.For the hydration effect analysis,NIR spectroscopy combined with the McCabe-Fisher method and aquaphotomics showed that the free hydrogen-bonded water fluctuates dynamically,with ethanol at 0-20%enhancing the hydrogen-bonded water clusters,while weak hydrogen-bonded water clusters were formed when the ethanol concentration increased continuously from 20%to 30%.These measurements provide new insights into the structural changes and changes in the hydration behavior of HSA,revealing the dynamic process of protein purification,and providing a theoretical basis for the selection of HSA alcoholic precipitation process parameters,as well as for further studies of complex biological systems.

Workspace and Accuracy Analysis on a Novel 6‑UCU Bone‑attached Parallel Manipulator

With the increasingly more extensive application of the medical surgical robot in the clinic,higher requirements have been put forward for medical robots.The bone-attached robot,a popular orthopedic robot in recent years,has a tendency of miniaturization and refinement.Thus,a bone-attached parallel manipulator(PM)based on 6-UCU(universalcylindrical-universal)configuration is proposed,which is characterized by small volume,compact structure,high precision and six-dimensional force feedback.To optimize the structure and make it more compact,the workspace of the 6-UCU PM is analyzed based on the analysis of three kinds of constraint,and workspace model is established through spherical coordinate search method.This study also analyzes the influence of structural parameters on workspace,which may contribute to improving the efficiency of design and ensuring small-sized robots possess relatively large workspace.Moreover,to improve the motion accuracy,an error modeling method is developed based on the structure of 6-UCU PMs.According to this established error model,the output pose error curves are drawn using MATLAB software when the structure parameters change,and the influence of the structure and pose parameters change on the output pose error of PMs is analyzed.The proposed research provides the instruction to design and analysis of small PMs such as bone-attached robots.

Identification of ChatGPT answers and physician answers in the online medical community

ChatGPT changes the way of knowledge production and information space structure of human society.In the healthcare industry,ChatGPT's powerful question-and-answer capability will drive its application in automated question answering in online healthcare communities.However,because ChatGPT answers are limited by factors such as the quality of data sets,their authority and accuracy cannot be guaranteed,and they are prone to misdiagnosis and damage to life and health.Therefore,the identification of ChatGPT answers in online medical communities with physician answers is crucial.In this paper,we collected medical question-answering data generated by the Haodafu platform and ChatGPT,respectively,constructed feature vectors from semantic features,syntactic features,and the fusion of both,and combined different feature vectors with XGBoost models to construct BERT-XGBoost,POS-XGBoost and Merge-XGBoost models for identifying ChatGPT answers and physician answers in online medical communities.The three models achieved accuracy rates of 0.960,0.968,and 0.986,respectively.The difference in performance between the three models reflects the degrees of variation in different features of ChatGPT answers versus physician answers.The results indicate that the differences between ChatGPT and physicians in syntactic features,i.e.,linguistic expression habits,are greater than their differences in semantic features,i.e.,specific content suggestions.

High-resolution, full-color quantum dot light-emitting diode display fabricated via photolithography approach

Displays play an extremely important role in modern information society,which creates a never-ending demand for the new and better products and technologies.The latest requirements for novel display technologies focus on high resolution and high color gamut.Among emerging technologies that include organic light-emitting diode(OL ED),micro light-emiting diode(micro-LED),quantum dot light-emitting diode(QLED),laser display,holographic display and others,QLED is promising owing to its intrinsic high color gamut and the possibility to achieve high resolution with photolithography approach.However,previously demonstrated photolthography techniques suffer from reduced device performance and color Impurities in subpixels from the process.In this study,we demonstrated a sacrificial layer assisted patterming(SLAP)approach,which can be applied in conjunction with photolithography to fabricate high-resolution,full-colo quantum dot(QD)patterns.In this approach,the negative photoresist(PR)and sacrificial layer(SL)were uilized to determine the pixels for QD deposition,while at the same time the SL helps protect the QD layer and keep it intact(named PR-SL approach).To prove this method's viability for QLED display manufacture,a 500-ppi,full-color passive matrix(PM)-QLED prototype was fabricated via this process.Results show that there were no color impurities in the subpixels,and the PM-QL ED has a high color gamut of 114%National Television Standards Committee(NTSC).To the best of our knowledge,this is the first ull-olor QLED prototype with such a high resolution.We anticipate that this innovative patteming technique will open a new horizon for future display technologies and may lead to a disruptive and innovative change in display industry.

Effects of in-situ TiB_(2)particles on machinability and surface integrity in milling of TiB_(2)/2024 and TiB_(2)/7075 Al composites

In-situ ceramics particle reinforced aluminum matrix composites are favored in the aerospace industry due to excellent properties.However,the hard ceramic particles as the reinforcement phase bring challenges to machining.To study the effect of in-situ TiB_(2)particles on machinability and surface integrity of TiB_(2)/2024 composite and TiB_(2)/7075 composite,milling experiments were performed,and compared with conventional 2024 and 7075 aluminum alloys.In-situ TiB_(2)particles clustered at the grain boundaries and dispersed inside the matrix alloy grains hinder the dislocation movement of the matrix alloy.Therefore,the milling force and temperature of the composites are higher than those of the aluminum alloys due to the increase of the strength and the decrease of the plasticity.In the milling of composites,abrasive wear is the main wear form of carbide tools,due to the scratching of hard nano-TiB_(2)particles.The composites containing in-situ TiB_(2)particles have machining defects such as smearing,micro-scratches,micro-pits and tail on the machined surface.However,in-situ TiB_(2)particles impede the plastic deformation of the composites,which greatly reduces cutting edge marks on the machined surface.Therefore,under the same milling parameters,the surface roughness of TiB_(2)/2024 composite and TiB_(2)/7075 composite is much less than that of2024 and 7075 aluminum alloy respectively.Under the milling conditions of this experiment,the machined subsurface has no metamorphic layer,and the microhardness of the machined surface is almost the same as that of the material.Besides,compared with 2024 and 7075 aluminum alloy,machined surfaces of TiB_(2)/2024 composite and TiB_(2)/7075 composite both show tensile residual stress or low magnitude of compressive residual stress.

The influence of nanosized precipitates on Portevin-Le Chatelier bands and surface roughness in AlMgScZr alloy

The influence of different precipitate-dislocation interactions,namely dislocation shearing and bypassing mechanisms,on PLC bands and the resultant surface roughness in AlMgScZr alloy was investigated.Three-dimensional surface roughness was quantitatively measured by confocal microscopy.We find that the introduction of shearable precipitates increases the stress amplitude,decreases the PLC bands number and surface roughness.However,the stress amplitude decreases,the PLC bands number and surface roughness increase with shearable precipitates turning to nonshearable precipitates.By analyzing the precipitation strengthening mechanisms quantitatively,the influence of precipitates on PLC bands and the resultant surface roughness was explored.Furthermore,our study demonstrates that the shearable precipitates can decrease the surface roughness by decreasing the number of PLC bands,which is instructive for designing structural materials with desirable mechanical property and surface quality.

Mitotic motor CENP-E cooperates with PRC1 in temporal control of central spindle assembly

Error-free cell division depends on the accurate assembly of the spindle midzone from dynamic spindle microtubules to ensure chromatid segregation during metaphase-anaphase transition.However,the mechanism underlying the key transition from the mitotic spindle to central spindle before anaphase onset remains elusive.Given the prevalence of chromosome instability phenotype in gastric tumorigenesis,we developed a strategy to model context-dependent cell division using a combination of light sheet microscope and 3D gastric organoids.Light sheet microscopic image analyses of 3D organoids showed that CENP-E inhibited cells undergoing aberrant metaphase-anaphase transition and exhibiting chromosome segregation errors during mitosis.Highresolution real-time imaging analyses of 2D cell culture revealed that CENP-E inhibited cells undergoing central spindle splitting and chromosome instability phenotype.Using biotinylated syntelin as an affinity matrix,we found that CENP-E forms a complex with PRC1 in mitotic cells.Chemical inhibition of CENP-E in metaphase by syntelin prevented accurate central spindle assembly by perturbing temporal assembly of PRC1 to the midzone.Thus,CENP-E-mediated PRC1 assembly to the central spindle constitutes a temporal switch to organize dynamic kinetochore microtubules into stable midzone arrays.These findings reveal a previously uncharacterized role of CENP-E in temporal control of central spindle assembly.Since CENP-E is absent from yeast,we reasoned that metazoans evolved an elaborate central spindle organization machinery to ensure accurate sister chromatid segregation during anaphase and cytokinesis.

A novel-green adsorbent based on betaine-modified magnetic nanoparticles for removal of methyl blue

A potential adsorbent based on betaine-modified magnetic iron oxide nanoparticles(BMNPs) was successfully synthesized by facile method, characterized and applied for methyl blue(MB) removal from aqueous solution. The characterization results of FTIR, transmission electron microscopy(TEM), X-ray diffraction(XRD) and vibrating sample magnetometer(VSM) showed that the prepared nanoparticles could be well dispersed in water and exhibited excellent superparamagnetism. These properties imply the potential to recycle BMNPs from wastewater through magnetic field. In the adsorption process, the effects of main experimental parameters such as p H of MB solution, initial concentration of MB, contact time, and adsorption capacity for MB were studied and optimized. These results demonstrated that large amounts of quaternary ammonium groups existing on the surface of BMNPs could promote absorption of MB via electrostatic forces. Additionally, the adsorption kinetics of MB was found to follow a pseudosecond-order kinetic model and the adsorption equilibrium data fitted very closely to the Langmuir adsorption isotherm model. The maximum adsorption capacity for MB was calculated to be 136 mg g 1at room temperature. Moreover, the BMNPs showed good reusability with 73.33% MB adsorption in the5 th cycle.

Porous polyetheretherketone microcarriers fabricated via hydroxylation together with cellderived mineralized extracellular matrix coatings promote cell expansion and bone regeneration

Porous microcarriers have aroused increasing attention recently by facilitating oxygen and nutrient transfer,supporting cell attachment and growth with sufficient cell seeding density.In this study,porous polyetheretherketone(PEEK)microcarriers coated with mineralized extracellular matrix(mECM),known for their chemical,mechanical and biological superiority,were developed for orthopedic applications.Porous PEEK microcarriers were derived from smooth microcarriers using a simple wet-chemistry strategy involving the reduction of carbonyl groups.This treatment simultaneously modified surface topology and chemical composition.Furthermore,the microstructure,protein absorption,cytotoxicity and bioactivity of the obtained porous microcarriers were investigated.The deposition of mECM through repeated recellularization and decellularization on the surface of porous MCs further promoted cell proliferation and osteogenic activity.Additionally,the mECM coated porous microcarriers exhibited excellent bone regeneration in a rat calvarial defect repair model in vivo,suggesting huge potential applications in bone tissue engineering.

Formation of ordered precipitates in Al-Sc-Er-(Si/Zr)alloy from first-principles study

The nucleation properties and stability of the ordered precipitates in Al-Sc-Er alloy were extensively studied by first-principles calculation.The calculated substitutional formation energy reveals that the dissolved Sc or Er in the Al matrix is very favorable to substitute the X sublattice site in L1_(2)-Al_(3)X(X=Sc/Er).The calculated solubility curve demonstrates the significant contribution of vibrational entropy to nucleation.The interface energies for Al/Al_(3)Sc,Al/Al_(3)Er and Al_(3)Sc/Al_(3)Er were calculated in the three directions of[100],[110]and[111],and we find that the interface structure in(100)plane is the most desirable,and the interface energy of Al/Al_(3)Er is the largest.Regardless of temperature and Sc/Er ratio,the L1_(2)-Al_(3)Sc_xEr_(1-x)precipitation phase mainly forms as the core-shell structure with Al3 Er as the core and Al_(3)Sc as the shell due to lower nucleation energy.The core-shell structure behaves higher stability once the particle radius is greater than 1 nm.Furthermore,the thermodynamic driving force for the segregating of Si or Zr in Al-Sc-Er alloy should accelerate the precipitation kinetics,where Si partitions occur preferentially to the Al_(3)Er and Zr partitions preferentially to the Al matrix.Overall,these theoretical results can offer solid explanations to the available experimental results.

Te-mediated electro-driven oxygen evolution reaction

In the 21^(st)century,the rapid development of human society has made people’s demand for green energy more and more urgent.The high-energy-density hydrogen energy obtained by fully splitting water is not only environmentally friendly,but also is expected to solve the problems caused by the intermittent nature of new energy.However,the slow kinetics and large overpotential of the oxygen evolution reaction(OER)limit its application.The introduction of Te element is expected to bring new breakthroughs.With the least electronegativity among the chalcogens,the Te element has many special properties,such as multivalent states,strong covalentity,and high electrical conductivity,which make it a promising candidate in electrocatalytic OER.In this review,we introduce the peculiarities of Te element,summarize Te doping and the extraordinary performance of its compounds in OER,with emphasis on the scientific mechanism behind Te element promoting the OER kinetic process.Finally,challenges and development prospects of the applications of Te element in OER are presented.

Interactions between cadmium and multiple precipitates in an Al-Li-Cu alloy:Improving aging kinetics and precipitation hardening

This work demonstrates significant improvements in both the aging kinetics and precipitation hardening of an Al-Li-Cu alloy with the minor addition of Cd(0.06 at.%).The precipitation hardening effect of T1 precipitates in casting Al-Li-Cu alloys has long been ignored since it is difficult to achieve a high number density of fine precipitates without a large number of dislocations.A detailed transmission electron microscopy investigation shows that the Cd addition has changed the distribution of T1 precipitates from the conventional uneven distribution near dislocations or grain boundaries to a more homogeneous manner.Most of the Cd-rich nanoparticles were observed at the broad face and/or terminal of the T1 platelets.It is highly likely that these nanoparticles act as heterogeneous nucleation sites,which consequently leads to a higher number density of T1 precipitates.Moreover,Cd atoms were preferentially segregated withinδprecipitates,which can be attributed to the strong bonding between Li and Cd.The interactions between Cd and the T1(Al2CuLi)andδ′(Al3Li)precipitates in Al-Li-Cu alloy are first reported.The present study may propose a new mechanism to effectively improve precipitation kinetics and therefore the age-hardening effect of Al-Li-Cu alloys.

Acetylation of ezrin regulates membrane–cytoskeleton interaction underlying CCL18-elicited cell migration

Ezrin,a membrane–cytoskeleton linker protein,plays an essential role in cell polarity establishment,cell migration,and division.Recent studies show that ezrin phosphorylation regulates breast cancer metastasis by promoting cancer cell survivor and promotes intrahepatic metastasis via cell migration.However,it was less characterized whether there are additional post-translational modifications and/or post-translational crosstalks on ezrin underlying context-dependent breast cancer cell migration and invasion.Here we show that ezrin is acetylated by p300/CBP-associated factor(PCAF)in breast cancer cells in response to CCL18 stimulation.Ezrin physically interacts with PCAF and is a cognate substrate of PCAF.The acetylation site of ezrin was mapped by mass spectrometric analyses,and dynamic acetylation of ezrin is essential for CCL18-induced breast cancer cell migration and invasion.Mechanistically,the acetylation reduced the lipid-binding activity of ezrin to ensure a robust and dynamic cycling between the plasma membrane and cytosol in response to CCL18 stimulation.Biochemical analyses show that ezrin acetylation prevents the phosphorylation of Thr567.Using atomic force microscopic measurements,our study revealed that acetylation of ezrin induced its unfolding into a dominant structure,which prevents ezrin phosphorylation at Thr567.Thus,these results present a previously undefined mechanism by which CCL18-elicited crosstalks between the acetylation and phosphorylation on ezrin control breast cancer cell migration and invasion.This suggests that targeting PCAF signaling could be a potential therapeutic strategy for combating hyperactive ezrin-driven cancer progression.

Measurement of dynamic membrane mechanosensation using optical tweezers

Many cellular processes are orchestrated by dynamic changes in the plasma membrane to form membrane projections and endocytic compartments in response to extracellular cue changes.Our previous studies show that post-translational modifications of ACAP4 regulate membrane dynamics and curvature in response to epidermal growth factor and chemokine(C−C motif)ligand 18 stimulation(Zhao et al.,2013;Song et al.,2018).