Surface Structure Research Articles

The surface defect of Fe2Ge (001) induces a synergistic spin effect and regulates the surface magnetism

The defect structure leads to the fracture and recombination of chemical bonds, lattice distortion, electron localization, etc., which has a significant improvement on the physical properties of materials, and give them new functions. The unique structure of Fe2Ge forms the surface structure of Ge end face and Fe end face in the direction of (001), but the surface is easy to form defect structure, and affecting its properties. It is found that the spin direction of Ge atom is opposite to the spin direction of Fe atom in perfect Fe2Ge (001) surface structure. When there is VGe defect, the magnetic moments of the perfect Fe2Ge (001) surface and Fe atoms are enhanced. When there are VFe, VFe-Ge and VGe-Fe defects, the magnetic moments of defects Fe2Ge (001) surface and Fe atoms are weakened. The reason is that the spin state electrons of Fe atoms induce Ge atoms to produce spin electrons, which forms a synergistic spin effect. The Hirshfeld Charge distribution and charge spin of Fe and Ge atoms are affected by the local potential field, Ge atoms are excited with spin direction of Fe atoms with VFe and VFe-Ge, and Ge atoms induce magnetic moments with spin direction of Fe atoms with VGe and VGe-Fe. The effects mechanism is that the five orbitals dzz, dxy, dzy, dzx and dxx-yy of Fe atom are greatly affected by the structure of the defect under the action of crystal field, while the s, px, py and pz orbitals are less affected. In VGe and VFe-Ge defects, the spin splitting of the d orbitals is larger to form a larger magnetic moment. In VFe and VGe-Fe defects, the d orbital spin splitting is smaller, and resulting in a smaller magnetic moment. The s, px, py and pz of Ge atoms are greatly affected, the spin splitting of pz is larger than that of px and py orbitals, and indicating that the spin of Ge atoms mainly comes from pz orbitals.

Innovative chitosan-onion polysaccharide composite films: A study on the preservation effects on cherry tomatoes.

Natural preservation materials have long been a focus of research in the quality control of fruits and vegetables. This study aimed to develop composite films with exceptional preservation properties by utilizing chitosan (CS) as the film-forming material and incorporating onion polysaccharide (ONP) as the active component. The CS-ONP composite films were prepared, and their performance and preservation effects were evaluated. The results demonstrated that increasing the ONP content significantly enhanced the shading, antimicrobial, and antioxidant capabilities of the CS-ONP composite films. Preservation experiments revealed that the CS-ONP composite films effectively delayed the quality decline of cherry tomatoes during storage. However, despite the improvements brought by ONP, certain drawbacks persisted, such as reduced mechanical properties and alterations in surface structure. In summary, the CS-ONP composite films exhibit promising potential as novel materials for fruit and vegetable preservation. PRACTICAL APPLICATION: The spoilage of fruits and vegetables can cause huge economic losses. This study addresses this challenge by using chitosan as the film-forming substrate and adding crude onion polysaccharide as the active ingredient to create composite films. The preservation effects of these films on cherry tomatoes were studied. Although only cherry tomatoes were tested in this study, the composite films demonstrated significant potential for broader applications in fruit and vegetable preservation.

Host-induced cell wall remodeling impairs opsonophagocytosis of Staphylococcus aureus by neutrophils.

Understanding how bacteria adapt to the host environment is critical in determining fundamental mechanisms of immune evasion, pathogenesis, and the identification of targets for new therapeutic approaches. Previous work demonstrated that Staphylococcus aureus remodels its cell envelope in response to host factors and we hypothesized that this may affect recognition by antibodies and thus killing by immune cells. As expected, incubation of S. aureus in human serum resulted in rapid binding of antibodies. However, as bacteria adapted to the serum, the increase in cell wall thickness resulted in a significant reduction in exposure of bound antibodies. This reduced antibody exposure, in turn, led to reduced killing by human neutrophils. Importantly, while antibodies bound to some cell surface structures became obscured, this was not the case for those bound to wall teichoic acid, which may have important implications for vaccine design.

Investigating structural property of human hair by using infrared free electron lasers

Intense infrared (IR) rays can heat matters and evaporate waters thermally. One of the possible applications will be hair dryer, although the irradiation effects of IR rays on the hair have not been fully explored. In this study, we first examined the interaction of IR rays at various wavelengths from 3.0 µm (near IR) to 90 µm (far IR) with the surface structure of human hair by using IR free electron lasers (FELs). IR-FEL is an accelerator-based pico-second pulse laser, and the feature is the wavelength-tunability with the high-photon density. When one thread of hair was irradiated by the FEL of 6–7 mJ energy at 60 µm, the cleavage occurred, and the morphological destruction was observed on scanning-electron microscopy images after the irradiations at 70 µm and 6.1 µm (amide I). Synchrotron-radiation infrared microspectroscopy showed that those FEL irradiations decreased a shoulder band at 1710 cm−1 that corresponds to carboxyl group in melanin or fatty acids and increased absorption intensity at 500–600 cm−1. On the contrary, the FEL at 90 µm little changed either the surface morphology or the infrared absorption spectra. Interestingly, near-IR FELs at 3.0–3.5 µm induced bending of a hair, and 2D mapping of protein secondary conformations revealed that β-sheet was more increased than the other conformations on the surface of the bending area even at low pulse energy (1–3 mJ). As a result, the structural damage of the hair was least at 90 µm, which implies an ideal wavelength for drying hair mildly.

Low-Temperature Plasma-Constructed Ni-Doped W18O49 Nanorod Arrays for Enhanced Electrocatalytic Oxygen Evolution and Urea Oxidation.

Surface engineering by doping and amorphization is receiving widespread attention from the perspective of the regulation of the electrocatalytic activities of electrocatalysts. However, the effective modulation of active sites on catalysts is still challenging. Herein, a straightforward and efficient method combining hydrothermal treatment with low-temperature plasma processing is presented to synthesize Ni-doped W18O49 nanorod arrays on carbon cloth with abundant oxygen vacancies (CC/WO-Ni-x). Mild plasma doping with Ni modifies the electronic structure of the W18O49 nanorod arrays, resulting in the formation of an amorphous structure that significantly reduces the electron transfer resistance. Additionally, the coupling with high-valent W6+ (derived from W18O49) leads to the partial preoxidation of doped Ni to form active Ni3+ species and oxygen vacancies. These features are collectively responsible for the remarkable oxygen evolution reaction (OER) and urea oxidation reaction (UOR) properties of CC/WO-Ni-4, for example, 10 mA cm-2 current density, an overpotential of 265 mV required for the OER under 1.0 M KOH solution. The addition of 500 mM urea to the 1.0 M KOH solution decreases the overpotential required for the same current density from 265 to 93 mV. This study provides insights into the modification of surface structures and presents an effective strategy to optimize the electrocatalytic active sites and enhance the efficiency of multifunctional electrocatalysts.

Asymmetric PDMS/PVDF Pervaporation Membrane for Separation of Ethanol/Water System

AbstractPreparing asymmetric pervaporation membranes is a kind of promising method to enhance pervaporation membrane flux. Hydrophobic PVDF polymer can be used to prepare asymmetric pervaporation membranes, but its separation factor is relatively low. In this work, to improve the performance of PVDF membrane pervaporation, PDMS polymer was added to the PVDF membrane, and asymmetric PDMS/PVDF permeable membranes were prepared by the non‐solvent induced phase separation (NIPS) method. The effects of mass ratios of PDMS to PVDF on the membrane structures and the membrane properties were characterized by SEM, XRD, FTIR, TGA, water contact angle and mechanical strength. The results showed that the ratios of the PDMS: PVDF affect its phase‐separation behavior. As the addition of PDMS increased, the finger‐like pores on the membrane section gradually became longer, the upper surface changed from less porous to porous structure, and the lower surface structure changed from interconnected flocculent structure to porous, and the best structure of the blend membrane was achieved when the PDMS: PVDF mass ratio was 1 : 5. Therefore, the membrane had the best separation performance in separating 15 wt. % ethanol aqueous solution with a permeate total flux of 273.65 g/(m2 h) and a separation factor of 9.09 when the mass ratio of PDMS: PVDF was 1 : 5.

Selective photocatalytic oxidation of 5‐hydroxymethylfurfural using Ce doped TiO2: a crucial role of defective sites

Transforming platform compounds with conventional catalysts, such as homogeneous and heterogeneous, into valuable chemicals encounters challenges associated with entailing high temperature/pressure and reusability during the reaction. To address these challenges, photocatalysis is one of the promising approaches, especially with visible‐light‐driven photocatalysts for selective transformation. A series of cerium‐doped TiO2 (CexTiO2; x= 0.5, 1, 3 and 5 wt%) are prepared via a simple coprecipitation method for the cocatalyst‐free selective oxidation of 5‐hydroxymethylfurfural (HMF) to 2,5‐diformylfuran (DFF) under visible light illumination. Introducing Ce into the network to TiO2 generates impurity energy levels, reduces the band gap, and extends the spectral response range. This also causes slight distortion to the surface structure, thereby originating defective sites and various surface oxygen species, confirmed by X‐ray photoelectron spectroscopy and electron paramagnetic resonance studies. The HMF adsorption studies infer that HMF forms a surface complex with CeTiO2, facilitating the formation of ligand‐to‐metal charge transfer complex (LMCT) under visible light (~ 420 nm), which efficiently catalyzes the conversion of HMF (54.4%) to DFF with a selectivity of >99%. In‐situ DRIFTS and surface passivation studies provide insight into the interaction between HMF and surface acidic/basic sites along with hydroxyl groups of CeTiO2, which subsequently convert selectively to DFF.

Efficient photoreduction of CO2 to tunable syngas by Zn-doped Co3O4: Tuning binding strength to versatile reaction intermediates simultaneously

Photochemical reduction of CO2 (CO2RR) to syngas is an attractive approach for carbon–neutral recycling. Manipulating binding strength to reactive species on catalyst surfaces is challenging but essential for achieving efficient syngas production with a desired CO/H2 ratio. Here, we demonstrate that the binding strength to key reaction intermediates (*CO2, *H and *CO) on the Co3O4 surface can be fine-tuned by incorporating varying amount of Zn atoms. Dedicated experiments and theoretical simulations unveil that Zn doping allows for simultaneous control of both CO2 adsorption/activation and the adsorption affinity of *CO on Zn-Co3O4 catalysts, resulting in a significant enhancement in CO2 to CO conversion. Moreover, Zn doping can alter the hydrophilicity of the catalyst surface, affecting the water adsorption behavior and adjusting the HER activity. As a result, the CO/H2 ratio can be readily tuned via varying the Zn doping level. This study presents an effective and economical method approach to manipulate the electronic structure of catalyst surfaces for controlling the kinetics of CO2RR and HER reactions, providing valuable insight into the design of highly active TMO-based photocatalysts for syngas production with a tailored CO/H2 ratio.

Interface engineering assisted La1-xSrxCoO3/FeOOH heterostructure as a high-performance electrocatalyst for oxygen evolution reaction

Perovskite oxides play a crucial role as catalysts in the oxygen evolution reaction (OER) owing to their distinctive structure and diverse physical and chemical characteristics. Currently, enhancing the electronic structure and specific surface area of the perovskite surface through strategic regulation poses a significant challenge in the advancement of perovskite catalyst development. Here, we propose a novel method for enhancing the OER activity of LaCoO3 (LCO) perovskite through atomic doping and interface engineering. The La0.6Sr0.4CoO3–FeOOH (Fe-LSCO) composite exhibits a notable enhancement in electrocatalytic performance, manifesting a low overpotential of 296.3 mV for the oxygen evolution reaction (OER) at a current density of 10 mA cm−2, while maintaining a high level of activity for a duration of 120 h. The enhanced activity of Fe-LSCO can be attributed to oxygen vacancy defects and the increase of the active site caused by A-site-doping and amorphous nanosheets of FeOOH, which synergistic effect reduces the energy barrier for water dissociation. The highly disordered surface and high surface energy of amorphous FeOOH render it highly active. This study presents a viable interface engineering approach for manipulating the reconstruction of the active phase in high-performance perovskite-based electrocatalytic materials.

Upstream CtrA-binding sites both induce and repress pilin gene expression in Caulobacter crescentus

Pili are bacterial surface structures important for surface adhesion. In the alphaproteobacterium Caulobacter crescentus, the global regulator CtrA activates transcription of roughly 100 genes, including pilA which codes for the pilin monomer that makes up the pilus filament. While most CtrA-activated promoters have a single CtrA-binding site at the − 35 position and are induced at the early to mid-predivisional cell stage, the pilA promoter has 3 additional upstream CtrA-binding sites and it is induced at the late predivisional cell stage. Reporter constructs where these additional sites were disrupted by deletion or mutation led to increased activity compared to the WT promoter. In synchronized cultures, these mutations caused pilA transcription to occur approximately 20 min earlier than WT. The results suggested that the site overlapping the − 35 position drives pilA gene expression while the other upstream CtrA-binding sites serve to reduce and delay expression. EMSA experiments showed that the − 35 Site has lower affinity for CtrA∼P compared to the other sites, suggesting binding site affinity may be involved in the delay mechanism. Mutating the upstream inhibitory CtrA-binding sites in the pilA promoter caused significantly higher numbers of pre-divisional cells to express pili, and phage survival assays showed this strain to be significantly more sensitive to pilitropic phage. These results suggest that pilA regulation evolved in C. crescentus to provide an ecological advantage within the context of phage infection.

Surface structure-based model to calculate thermal and optical properties in nanoscale and quantum dot semiconductors

Surface combination structure was used to design the construction of nano and quantum films, particles, and dots. The created model was applied to tetrahedral semiconductor nanoparticles and quantum dots with a successful performance. It works better than reported experimental data across the whole size range, from the bulk state to the critical size of quantum dots. The model helps to figure out the melting point that changes with the nanosize scale as applied on Si and Sn, which are simple tetrahedral semiconductors, and for CdS and CdSe, which are among II-VI group compounds. It was also used to calculate melting-related parameters such as cohesive energy, Debye temperature, vibrational entropy, and melting enthalpy. The nanosize dependence of the lattice volume and the atom's ionization energy describes the solid surface structure. From the model, an equation was obtained to calculate the energy gaps in Si, CdS, and CdSe particles that are nano- and quantum-dot-sized, and the results are compared to the experimental data that goes with these particles.

Low Temperature NO and CO Conversion with a Mechanistic Approach on Ru-Composed Cerium Oxide.

Catalytic reduction of NO with CO at a lower temperature is an extremely challenging task, thus requiring conceivable surfaces to overcome such issues. Ru-substituted CeO2 catalysts prepared via the solution combustion method were employed in CO oxidation and NO-CO conversion studies. The characterization for material formation and surface structure was carried out through XRD, SEM, TEM, and BET surface area. The catalytic study revealed the promising behavior of 5% Ru in CeO2 for the 100% conversion of NO-CO at 150 °C, proving it to be an excellent exhaust material. These observed results are also supported by temperature-programmed studies, i.e. TPD of NO and CO in addition to NH3-TPD and H2-TPR for their convincible surface interaction that is inclined toward a significant change in the conversion path. Additionally, the proposed mechanism, based on the experimental evidence, sheds light on the NO-CO redox reaction, directing the reaction pathway toward the Langmuir-Hinshelwood and Mars-Van Krevelen-type route. Moreover, the exceptional performance can be attributed to the strategic incorporation of Ru in CeO2, where the strong interaction of Ru-Ce is able to gain a high synergy for NO and CO conversion.

Enhancement mechanism of microbial mineralization modified coal gangue aggregate properties

Preparing concrete with coal gangue as the aggregate has significant environmental and economic advantages. Nevertheless, the fundamental characteristics of the manufactured concrete are significantly impacted by the high water absorption and low strength of coal gangue aggregate. The present study employs the microbial-induced carbonate precipitation (MICP) technique to efficiently enhance the characteristics of coal gangue aggregate (CGA). Starting from the circumstances of microbial mineralization, the effects of pH, temperature, and time on the capacity of bacteria for mineralization were taken into consideration. Following solution immersion treatment with varying concentrations of urea, calcium ions, and bacterial solution, the patterns of water absorption, crushing index, apparent density, and ultrasonic pulse resistance of CGA were examined. The precipitates produced by microbial mineralization, the micro-morphology, and the pore structure of the aggregate surface were all characterized, and the mechanism of the modification of CGA by MICP was revealed through the use of scanning electron microscopy (SEM), X-ray diffractometer (XRD), and nuclear magnetic resonance (NMR) techniques. Investigations were also conducted on the mechanical characteristics of modified coal gangue aggregate concrete. The results showed that the water absorption and crushing index of the CGA with optimal modification effect (M-CGA) decreased by 18.5 % and 24.1 %, respectively, which was attributed to the fact that the calcium carbonate formed in the cracks and pores of the CGA filled the aggregates and prevented the penetration of water. The 28-day compressive strength, split tensile strength, and flexural strength of modified coal gangue aggregate concrete prepared from M-CGA were increased by 8.13 %, 13.88 %, and 8.53 %, respectively. MICP is an effective method to improve the properties of CGA, which is conducive to the waste recycling of coal gangue.

INNOVATIVE ANALYSIS OF MUD VOLCANO PATTERNS IN WESTERN AND SOUTHWESTERN PAKISTAN THROUGH SATELLITE IMAGERY

Mud volcanoes are geological features formed due to pressurized mud, water, gases accompanied by rocks that are expelled to the surface from underground. In Pakistan, there are more than 80 mud volcanoes. However, there is a lack of extensive, thorough mapping and analysis of Pakistan's mud volcanoes in the West and Southwest utilizing satellite image technologies. The present study aims to locate various clusters in South Western and Western regions of Pakistan, and to make a laboratory scale and conceptual model of mud volcanoes in this region to understand the underlying geological and tectonic processes. Firstly, we have used high-resolution satellite images to demarcate and identify various clusters and individual mud volcanoes. Secondly, mud volcanoes of a lesser-known western segment of Pakistan are the unexplored Pishin Basin (Qila Saifullah, Babu Cheena, Zhob). These mud volcanoes occur in distinct patterns which is the regional trend of Makran subduction zone and Pishin Basin. These mud volcanoes occur in clusters (Hingol National Park), and follow the regional structural trend of lineaments. Tracing these lineaments can help in the identification of more mud volcanoes. These active mud volcanoes release methane and hydrocarbons along with mud and water and can be identified by changes in the tone, and texture (Ormara) of the satellite image. However, few fossil or extinct mud volcanoes still have eroded (Gwadar) craters and are relatively diminished in size (~50m). They exhibit a wide variety of surface structures extruding gas and sometimes with bubbles having viscous hot fluid of mud. It could signify the presence of hydrocarbons beneath the surface. Chandragup mud volcano is an attractive place for Hindus, as they consider it a holy place. They are also important as a geoheritage and tourist sight and can generate significant revenue. Hingol National Park is a captivating site for those all over the world who adore to grasp nature thoroughly. These are significant as similar settings in other countries like Azerbaijan, Romania and New Zealand hold immense petroleum, geoheritage, geotourism and geothermal potential.

Photoredox Cascade Catalysts for Solar Hydrogen Production from Sustainable Hydrogen Sources.

Visible-light-driven photocatalytic hydrogen (H2) production has been extensively studied as a clean and sustainable energy resource. Although sacrificial electron donors (SEDs) are commonly used to evaluate photocatalytic activity, their irreversible decomposition forces charge separation, which disrupts the inherent dual productivity of photocatalysis, that is, the formation of both the reduction and oxidation products. To achieve highly efficient photoinduced charge separation without SED decomposition, the layer-by-layer assembly of redox-active photosensitizing dyes and electron mediators through Zr4+-phosphonate bonds has been extensively studied as an artificial mimic of the electron transport chain in natural photosynthesis. This concept paper presents an overview of photoredox cascade catalytic (PRCC) systems comprising multiple Ru(II)-trisbipyridine-type dyes and mediator layers on Pt-loaded TiO2 nanoparticles for H2 production from redox reversible electron donors (RREDs). The PRCC structure-activity relationship for photocatalytic H2 production is briefly discussed in terms of layer thickness, surface structure and modification, and cooperativity with molecular oxidation catalysts. Finally, new insights into the design of efficient dual-production photocatalysts based on the PRCC structure are presented.

Screening of Ultra‐Efficient Visible Light Catalysts via Material Modification to Activate Electron Polarization Inside the Material

The high catalytic activity of photocatalysts is greatly influenced by the efficient separation of photogenerated charge carriers. In this study, six g‐C3N4‐based COFs are designed and synthesized, and CN‐203 is identified as the most efficient photocatalyst through experimental screening. Quantitative measurements reveal that singlet oxygen production is ≈100 times that of ·O2− and 5000 times that of ·OH. When combined with PMS, CN‐203 exhibits degradation rates for RhB and TC that are ≈30 (k = 0.0293 s−1) and 10 (k = 0.2940 min−1) times faster than those of CN550(RhB, k = 0.0531 min−1; TC, k = 0.0301 min−1), respectively. Structural simulations and calculations show that the modified CN‐203 have better electron–hole separation in the excited state, and the energy gap between HOMO and LUMO is significantly reduced after modification. The study also revealed the structure–function relationship between the modification of the same site with different functional groups and its effect on photocatalysis. Overall, this study provides valuable insights into the relationship between surface structure and photocatalytic applications.

Nonlinear change of ion-induced secondary electron emission in the κ-Al2O3 surface charging from first-principle modelling

Secondary electron emission (SEE) induced by the positive ion is an essential physical process to influence the dynamics of gas discharge which relies on the specific surface material. Surface charging has a significant impact on the material properties, thereby affecting the SEE in the plasma-surface interactions. However, it does not attract enough attention in the previous studies. In this paper, SEE dependent on the charged surface of specific materials is described with the computational method combining a density functional theory (DFT) model from the first-principle theory and the theory of Auger neutralization. The effect of κ-Al2O3 surface charge, as an example, on the ion-induced secondary electron emission coefficient (SEEC) is investigated by analyzing the defect energy level and band structure on the charged surface. Simulation results indicate that, with the surface charge from negative to positive, the SEEC of a part of low ionization energy ions (such as E i = 12.6 eV) increases first and then decreases, exhibiting a nonlinear changing trend. This is quite different from the monotonic decreasing tendency observed in the previous model which simplifies the electronic structure. This irregular increase of the SEEC can be attributed to the lower escaped probability of orbital energy. The results further illustrate that the excessive charge could cause the bottom of the conduction band close to the valence band, thus leading to the decrease of the orbital energy occupied by the excited electrons. The nonlinear change of SEEC demonstrates a more realistic situation of how the electronic structure of material surface influences the SEE process. This work provides an accurate method of calculating SEEC from specific materials, which is urgent in widespread physical scenarios sensitive to surface materials, such as increasingly growing practical applications concerning plasma-surface interactions.

Oxygen‐Vacancy‐Assisted Dual Functional Surface Coatings Suppressing Irreversible Phase Transition of Li‐Rich Layered Oxide Cathodes

AbstractBoth lattice oxygen release and the migration of transition metal (TM) ions challenge the cyclability of Li‐rich Mn‐based layered oxide (LMO) cathodes by inducing irreversible phase transitions. In this work, the oxygen‐vacancy‐assisted dual functional surface coatings of Li‐rich layered oxide cathodes, including a spinel‐over‐phase and a Li3PO4 layer are fabricated for lithium‐ion batteries (LIBs). The functional role of the optimized interface is mainly focused. Specifically, during the process of reorganized surface structure, the oxygen vacancies function as active sites for migrating TM ions to form the spinel over‐phase and deliver the decreased binding energy of PO43− on the LMO surface. It is found that the Li3PO4 layer increases the migration energy barrier of TM ions to 13.38 eV (7.62 eV for LMO). As a result, both the spinel over‐phase and the Li3PO4 layer synergistically inhibited the irreversible phase transitions of LMO upon cycling to boost lithium storage of the cathodes. The optimized cathode maintained higher capacity retention of 95% at 0.2 C after 200 cycles in comparison to 67% for the pristine LMO. This study provides some understanding of the functional roles of the optimized dual surface coatings in suppressing the irreversible phase transition of LMO for LIBs.

When the Host Encounters the Cell Wall and Vice Versa.

Peptidoglycan (PGN) and associated surface structures such as secondary polymers and capsules have a central role in the physiology of bacteria. The exoskeletal PGN heteropolymer is the major determinant of cell shape and allows bacteria to withstand cytoplasmic turgor pressure. Thus, its assembly, expansion, and remodeling during cell growth and division need to be highly regulated to avoid compromising cell survival. Similarly, regulation of the assembly impacts bacterial cell shape; distinct shapes enhance fitness in different ecological niches, such as the host. Because bacterial cell wall components, in particular PGN, are exposed to the environment and unique to bacteria, these have been coopted during evolution by eukaryotes to detect bacteria. Furthermore, the essential role of the cell wall in bacterial survival has made PGN an important signaling molecule in the dialog between host and microbes and a target of many host responses. Millions of years of coevolution have resulted in a pivotal role for PGN fragments in shaping host physiology and in establishing a long-lasting symbiosis between microbes and the host. Thus, perturbations of this dialog can lead to pathologies such as chronic inflammatory diseases. Similarly, pathogens have devised sophisticated strategies to manipulate the system to enhance their survival and growth.

Cheese Whey Protein and Blueberry Juice Mixed Fermentation Enhance the Freeze-Resistance of Lactic Acid Bacteria in the Freeze-Drying Process

The effects of MRS, whey protein and blueberry alone, and mixed fermentation on the survival rate of lactic acid bacteria under various freeze-drying conditions were investigated. The surface structure of the freeze-dried powders was also investigated to explore the anti-freezing protection mechanism of mixed whey protein and blueberry fermentation on the bacteria. It was found that the mixed fermentation medium of blueberry and whey protein has a protective effect on the freeze-drying bacteria and is better than the traditional MRS and whey protein medium. The optimal concentration of blueberry juice addition was 9%. The survival rate of the pre-freezing temperature at −80 °C was higher than at −20 °C after the pre-freezing and freeze-drying processes. The freeze-drying thickness of 0.3 cm could improve the survival rate of the bacteria. The Fourier transform infrared spectroscopy results indicated the interaction between the whey protein, anthocyanins, and the surface composition of the lactic acid bacteria.