Crystalline Surface Layer Research Articles

Correlating gas permeability and morphology of bio-based polyether-block-amide copolymer membranes by IR nanospectroscopy

The gas permeability of polymer membranes is determined by their nanoscale morphology, which strongly depends on the membrane fabrication. Here, we demonstrate how the correlation between gas permeability and fabrication-dependent nanoscale morphology of polymer membranes can be elucidated by infrared (IR) nanospectroscopy based on elastic IR scattering at an atomic force microscope tip. Specifically, we fabricated membranes of PEBAX® RNEW – a bio-based polyether-block-amide copolymer – by solvent casting and extrusion, achieving unprecedented CO2 permeability and CO2/N2 selectivity for the solvent-cast membranes. For the extruded membranes, however, we found an about 50 % reduced CO2 permeability, which could not be explained by differential scanning calorimetry and conventional IR spectroscopy. In contrast, IR nanospectroscopy revealed a highly crystalline polyether oxide (PEO) surface layer on the extruded membranes, not observed for the solvent-cast membranes. Annealing of the extruded membranes at 110 °C transformed the crystalline into amorphous PEO layers, as confirmed by IR nanospectroscopy, yielding a gas permeability close to that of the solvent-cast membranes. We thus attribute the dramatic gas reduction of the extruded membranes to their highly crystalline surface layers. Generally, studying polymer morphology by IR nanospectroscopy provides valuable information for better understanding the local gas permeability properties of polymer membranes.

Sintering and crystallization kinetics of bioactive glass 13–93

This study investigates the sintering and crystallization behavior and kinetic of the bioactive glass (BG) 13–93 with nominal composition (in mol%): 54.6 SiO2 - 1.7 P2O3 - 22.1 CaO - 6.0 Na2O - 7.9 K2O - 7.7 MgO. Sintering and crystallization were investigated non-isothermally for various particle size fractions smaller than 315 µm as well as for bulk samples. Densification was not hindered by the presence of crystalline phases across all particle size fractions. Afterwards, wollastonite was found as the dominant crystal phase at higher temperature which resorb primary surface precipitation-like quartz crystallites. The growth direction shifts into volume when the sample surface is nearly covered. The crystal growth rate of wollastonite was calculated from the crystalline surface layer thickness measured during heating. The findings of this study are relevant for the high temperature processing of BG 13–93.

Impact of Ball Milling on the Hydrogen Evolution Performance of Cu2Sn0.38Ge0.62S3 Photocatalytic Particles Synthesized via a Flux Method.

Ball milling has been shown empirically to produce fine photocatalytic particles from large bulky particles but to drastically reduce the photocatalytic activity of such material during water splitting due to mechanical damage to the photocatalyst surfaces. If the damaged photocatalyst surfaces could be removed or reconstructed, the reduced particle sizes resulting from milling would be expected to provide enhanced photocatalytic activity. In the present study, fine particles of crystalline Cu2Sn0.38Ge0.62S3 (CTGS), which is responsive to long wavelength light up to the near-infrared region, were synthesized by a flux method and subsequent ball milling. A photocathode made of such particles showed significantly enhanced photoelectrochemical (PEC) performance under simulated sunlight while the photocatalytic hydrogen evolution activity of a powder suspension system made from the same material exhibited a typical decrease. The CTGS crystalline particles synthesized using the flux method were found to be highly crystalline but to have relatively large micrometer-scale sizes. Ball milling reduced the particle size but produced an amorphous coating of oxidized species that lowered the photocatalytic activity of the powder suspension system. Typical surface modifications of a photocathode made from this material, consisting of wet chemical processes, also served as an etching treatment to successfully remove the minimally crystalline surface layer and provide greater PEC activity. These data suggest the benefits of combining flux crystal growth with ball milling and the appropriate chemical etching process to obtain high-crystallinity fine photocatalytic particles responsive to long wavelength light with improved PEC hydrogen evolution activity.

Surface layer protein A from hypervirulent Clostridioides difficile ribotype 001 can induce autophagy process in human intestinal epithelial cells

Clostridioides difficile is the leading cause of nosocomial diarrhea with high morbidity and mortality worldwide. C. difficile strains produce a crystalline surface layer protein A (SlpA), which is an absolute necessity for its pathogenesis. However, its pathogenic mechanisms and its pro-inflammatory behavior are not yet fully elucidated. Herein, we report for the first time that SlpA extracted from C. difficile can induce autophagy process in Caco-2 cells. SlpA protein was purified from two C. difficile strains (RT001 and ATCC 700075). The cell viability of Caco-2 cells after exposure with different concentrations (15, 20, 25 μg/mL) of SlpA at various time points (3, 6, 12, 24 h) was measured by MTT assay. Acridine orange staining was used to visualize the hypothetical acidic vesicular organelles. The gene expression of autophagy mediators including LC3B, Atg5, Atg16L, and Beclin-1 was determined by quantitative real-time PCR assay. Western blotting assay was used to detect the expression of LC3B protein. MTT assay showed that different concentrations of SlpA did not induce significant changes in the viability of Caco-2 cells. SlpA at concentration of 20 μg/mL enhanced the formation of acidic vesicular organelles in Caco-2 cells after 12 h of exposure. Moreover, SlpA treatment significantly increased the expression of autophagy-associated genes, and increased the expression of LC3B protein in Caco-2 cells. In conclusion, our study demonstrated that SlpA is capable to induce autophagy in intestinal epithelial cells. These findings reveal a novel mechanism for the pathogenesis of C. difficile mediated by its SLPs.

Characterisation of enzyme catalysed hydrolysation stage of poly(lactic acid) fibre surface by nanoscale thermal analysis: New mechanistic insight

Enzyme catalysed hydrolysis of bio-based poly(lactic acid) (PLA) represents an environmentally-friendly route for a controlled modification of polymer fibres. In this work, the topochemical hydrolysis reaction of cutinase from Humicola insolens (HiC) on PLA fibre was mechanistically investigated using the advanced surface sensitive nanoscale thermal analysis (nano-TA) technique. The enzymatic hydrolysis preferentially occurs at the amorphous regions of the fibre outer layer, thus leading to randomised hydrolysis, monomer release and ablation of the fibre surface during the initial phase of the hydrolysis. Due to the higher hydrolysis rate at amorphous regions, the crystallinity of the fibre outer layer increases. As a result, an enrichment in overall fibre crystallinity is observed by increased melting enthalpy. The accessibility of the enzyme to the fibre core is restricted, thus the change in crystallinity is prevalent on the fibre outer region. The observed increase of the surface softening temperature from the glass transition temperature close to the melting on-set of crystalline PLA as detected by nano-TA supports the hypothesis, that selective hydrolysis preferably takes place at the amorphous region at the fibre outer layer, thus leading to modified PLA fibres with an unchanged fibre core and a very thin and highly crystalline surface layer.

Genetic diversity and phylogenetic analysis of the surface layer protein A gene (slpA) among Clostridioides difficile clinical isolates from Tehran, Iran

Clostridioides difficile is the most common causative agent of healthcare-associated diarrhea. C. difficile strains produce a crystalline surface layer protein (SlpA), encoded by the slpA gene. Previous studies have shown that SlpA varies among C. difficile strains. In this study, we used the SlpA sequence-based typing system (SlpAST) for the molecular genotyping of C. difficile clinical isolates identified in Iran; the PCR ribotypes (RTs) and toxin profiles of the isolates were also characterized. Forty-eight C. difficile isolates were obtained from diarrheal patients, and characterized by capillary electrophoresis (CE) PCR ribotyping and the detection of toxin genes. In addition, the genetic diversity of the slpA gene was investigated by Sanger sequencing. The most common RTs were RT126 (20.8%), followed by RT001 (12.5%) and RT084 (10.4%). The intact PaLoc arrangement representing cdu2+/tcdR+/tcdB+/tcdE+/tcdA+/tcdC+/cdd3+ profile was the predominant pattern and cdtA and cdtB genes were found in one-third of the isolates. Using the SlpA genotyping, 12 main genotypes and 16 subtypes were identified. The SlpA type 078–1 was the most prevalent genotype (20.8%), and identified within the isolates of RT126. The yok-1, gr-1, cr-1 and kr-3 genotypes were detected in 14.5%, 12.5%, 12.5% and 8.3% of isolates, respectively. Almost all the isolates with the same RT were clustered in similar SlpA sequence types. In comparison to PCR ribotyping, SlpAST, as a simple and highly reproducible sequenced-based technique, can discriminate well between C. difficile isolates. This typing method appears to be a valuable tool for the epidemiological study of C. difficile isolates worldwide.

Hydrolytic degradation of porous poly(hydroxybutyrate-co-hydroxyvalerate) scaffolds manufactured using selective laser sintering

The long-term hydrolytic degradation of porous poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) bone scaffolds manufactured using Selective Laser Sintering (SLS) process have yet to be explored. In this study, SLS PHBV scaffolds were incubated in phosphate-buffered saline (PBS) solution for up to 20 weeks. The result showed that degradation of the PHBV scaffolds occurred predominantly by bulk degradation. With increasing incubation time, the molecular weight and compressive stiffness of the scaffolds reduced while their crystallinity increased. In the first 8 weeks, the weight loss of the scaffolds was insignificant, indicating very limited amount of soluble product was produced by the hydrolysis process. Weight loss started to occur from Week 8; the average weight loss per fortnight was minimal and in the range of 0.33-0.51 %. The pristine PHBV scaffolds had a highly crystalline surface layer with low concentration of the hydrophilic carboxylic acid (COOH) end-groups. The concentration of COOH groups on the scaffold surface increased initially upon immersion in PBS due to the preferential chain rearrangement to expose hydrophilic segments. During immersion surface hydrolysis proceeded and the quantity of COOH groups declined from Week 2 to 6 due to erosion of the surface layer.

Nano-devitrification and structural evolution of amorphous state in surface Ti-Ta-based alloy fabricated on TiNi substrate through additive thin-film electron-beam synthesis

Thin film metallic glasses (TFMGs) have a high application potential in MEMS industry. An important issue in ensuring the reliability of the functional properties of TFMGs (fatigue endurance, hysteresis-free response) is their thermal stability during operation. The problem of handling of the crystallization processes in the amorphous alloys is crucial for the understanding of structure-property relationships in the TFMGs. In this work, by liquid-phase mixing of the system [Ti-Ta film/TiNi substrate] using a low-energy high-current electron beam the surface Ti-Ni-Ta alloy (denoted as [Ti-Ni-Ta]SA) was fabricated. The thermal stability and crystallization behavior in the [Ti-Ni-Ta]SA upon devitrification were studied. According to the results of microstructural XRD/SEM/TEM analysis, in the as-received [Ti-Ni-Ta]SA a thin ~ 400 nm amorphous sublayer beneath the crystalline surface layer was observed. Devitrification of the [Ti-Ni-Ta]SA on heating at T = 773 K led to the formation of a nanocomposite structure, in which the phase composition was represented by a mixture of α"(Ti,Ta) martensitic phase, β(Ti,Ta) phase, precipitates of the η'-(Ti,Ta)2Ni intermetallic phase and a small amount of residual amorphous phase. The mechanisms of crystal nucleation and growth in an amorphous matrix were determined, and a scheme of phase transformations from an amorphous to a crystalline state was proposed. The crystallization of the amorphous phase occurred in two stages, including (i) the precipitation of primary β+α" grains and (ii) the growth of the β grains and the precipitation of η'-(Ti,Ta)2Ni intermetallic phases in the inter-dendritic areas, as well as in the interfaces by the eutectic crystallization mechanism.

Surface oxidation and crystallization of FeNi-Based soft magnetic nanocrystalline and amorphous nanocomposite alloys

In this work, we present characterization of surface oxidation and crystallization behavior of Metal Amorphous Nanocomposite (MANC) (Fe 70 Ni 30 ) 80 Nb 4 Si 2 B 14 alloys via complementary x-ray diffraction, electron microscopy, and x-ray photoelectron spectroscopy techniques. An adherent amorphous oxide of roughly 15–20 nm in thickness is observed on the wheel side of the ribbon, enriched in Fe relative to Ni and with significant content of Si and Nb as would be expected based upon a comparison of the Gibbs free energy of formation of the stable oxide phases. The amorphous character of the oxide is likely to result from the significant Si-content coupled with the amorphous and nanocrystalline character of the underlying metallic layer. Higher density of FeNi-enriched nanocrystals is also observed within ∼100 nm of the wheel-side surface, presumably due to reduction in local glass former concentration. A rough, crystalline copper oxide layer is also present and forms through contact between the copper wheel and the solidifying melt during the rapid solidification process. On the air side of the ribbon, a crystalline oxide layer of ∼15–20 nm is formed as well as intergranular oxidation that penetrates along the grain boundaries between highly textured surface crystallites of ∼50–100 nm in size. The crystalline nature of the oxide on these surfaces is asserted to result from the lack of significant Si-content and the pre-existing surface crystallites that form during the rapid solidification process which promote a crystalline oxide surface layer. These results shed new insights into the details of surface oxidation and can help to inform processing and alloy composition adjustments which seek to tailor surface properties.

Formation of planar hybrid lipid/polymer membranes anchored to an S-layer protein lattice by vesicle binding and rupture

ABSTRACT Exploitation of biomolecular and biomimetic components on solid surfaces gain increasing importance for the design of stable functional platforms. The present study performed by quartz crystal microbalance with dissipation monitoring (QCM-D) reports on the formation of planar hybrid lipid/polymer membranes anchored to a crystalline surface (S-) layer protein lattice. In this approach, hybrid lipid/polymer vesicles were chemically bound to the S-layer protein lattice. Subsequently, to form a hybrid planar layer rupture and fusion was triggered either by (1) β–diketone – europium ion complex formation or (2) successive application of calcium ions, lowering the pH from 9 to 4, and the detergent CHAPS. As determined by QCM-D, method 1 resulted for a polymer content of 5% in a planar membrane with some imbedded intact vesicles, whereas method 2 succeeded in planar hybrid membranes with a polymer content of even up to 70%. These results provide evidence for the effective formation of planar lipid/polymer membranes varying in their composition on an S-layer protein lattice.

Formation and characteristics of mixed lipid/polymer membranes on a crystalline surface-layer protein lattice.

The implementation of self-assembled biomolecules on solid materials, in particular, sensor and electrode surfaces, gains increasing importance for the design of stable functional platforms, bioinspired materials, and biosensors. The present study reports on the formation of a planar hybrid lipid/polymer membrane on a crystalline surface layer protein (SLP) lattice. The latter acts as a connecting layer linking the biomolecules to the inorganic base plate. In this approach, chemically bound lipids provided hydrophobic anchoring moieties for the hybrid lipid/polymer membrane on the recrystallized SLP lattice. The rapid solvent exchange technique was the method of choice to generate the planar hybrid lipid/polymer membrane on the SLP lattice. The formation process and completeness of the latter were investigated by quartz crystal microbalance with dissipation monitoring and by an enzymatic assay using the protease subtilisin A, respectively. The present data provide evidence for the formation of a hybrid lipid/polymer membrane on an S-layer lattice with a diblock copolymer content of 30%. The hybrid lipid/polymer showed a higher stiffness compared to the pure lipid bilayer. Most interestingly, both the pure and hybrid membrane prevented the proteolytic degradation of the underlying S-layer protein by the action of subtilisin A. Hence, these results provide evidence for the formation of defect-free membranes anchored to the S-layer lattice.

Topologically-guided continuous protein crystallization controls bacterial surface layer self-assembly

Many bacteria and most archaea possess a crystalline protein surface layer (S-layer), which surrounds their growing and topologically complicated outer surface. Constructing a macromolecular structure of this scale generally requires localized enzymatic machinery, but a regulatory framework for S-layer assembly has not been identified. By labeling, superresolution imaging, and tracking the S-layer protein (SLP) from C. crescentus, we show that 2D protein self-assembly is sufficient to build and maintain the S-layer in living cells by efficient protein crystal nucleation and growth. We propose a model supported by single-molecule tracking whereby randomly secreted SLP monomers diffuse on the lipopolysaccharide (LPS) outer membrane until incorporated at the edges of growing 2D S-layer crystals. Surface topology creates crystal defects and boundaries, thereby guiding S-layer assembly. Unsupervised assembly poses challenges for therapeutics targeting S-layers. However, protein crystallization as an evolutionary driver rationalizes S-layer diversity and raises the potential for biologically inspired self-assembling macromolecular nanomaterials.

Nonulosonic acids contribute to the pathogenicity of the oral bacterium Tannerella forsythia.

Periodontitis is a polymicrobial, biofilm-caused, inflammatory disease affecting the tooth-supporting tissues. It is not only the leading cause of tooth loss worldwide, but can also impact systemic health. The development of effective treatment strategies is hampered by the complicated disease pathogenesis which is best described by a polymicrobial synergy and dysbiosis model. This model classifies the Gram-negative anaerobe Tannerella forsythia as a periodontal pathogen, making it a prime candidate for interference with the disease. Tannerella forsythia employs a protein O-glycosylation system that enables high-density display of nonulosonic acids via the bacterium's two-dimensional crystalline cell surface layer. Nonulosonic acids are sialic acid-like sugars which are well known for their pivotal biological roles. This review summarizes the current knowledge of T. forsythia's unique cell envelope with a focus on composition, biosynthesis and functional implications of the cell surface O-glycan. We have obtained evidence that glycobiology affects the bacterium's immunogenicity and capability to establish itself in the polymicrobial oral biofilm. Analysis of the genomes of different T. forsythia isolates revealed that complex protein O-glycosylation involving nonulosonic acids is a hallmark of pathogenic T. forsythia strains and, thus, constitutes a valuable target for the design of novel anti-infective strategies to combat periodontitis.

Defect-induced room-temperature visible light luminescence in Mg2Si:Al films

The Al-doped Mg2Si thin films were fabricated on sapphire substrates by magnetron sputtering technique, and the influences of different Al doping contents on the Raman scattering and room-temperature (RT) photoluminescence (PL) of Mg2Si thin films were investigated. The crystal structure, morphology, composition, Raman scattering and PL property of the thin film were examined using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy, respectively. XRD results indicate that the intensity of diffraction peaks of Al-doped Mg2Si thin films are higher than that of undoped Mg2Si thin film, and decrease with increasing Al doping content. The FESEM image shows a few cavities in the surface of the film. The EDS results show that the thin films have the Al content of 0, (1.17 ± 0.1) at.%, (1.53 ± 0.1) at.%, (1.86 ± 0.08) at.% and (2.76 ± 0.11) at.%, respectively. The results of Raman scattering measurement reveal that all samples have the characteristic peak of Mg2Si. And Al dopant-induced Raman peak centered at 441 cm−1 was detected. Room-temperature photoluminescence of the Mg2Si:Al film was observed for the first time. Two visible light luminescence peaks center about 580 nm (2.14 eV) and 630 nm (1.97 eV), respectively, which originate from the different energy levels transition at the interface between crystalline Mg2Si and MgO surface layer. With decreasing excitation power, the position of the maximum of PL has no obvious change and the intensity drops significantly.

Diffractive X-ray Waveguiding Reveals Orthogonal Crystalline Stratification in Conjugated Polymer Thin Films

The depth dependence of crystalline structure within thin films is critical for many technological applications, but has been impossible to measure directly using common techniques. In this work, by monitoring diffraction peak intensity and location and utilizing the highly angle-dependent waveguiding effects of X-rays near grazing incidence we quantitatively measure the thickness, roughness and orientation of stratified crystalline layers within thin films of a high-performance semiconducting polymer. In particular, this diffractive X-ray waveguiding reveals a self-organized 5-nm-thick crystalline surface layer with crystalline orientation orthogonal to the underlying 65-nm-thick layer. While demonstrated for an organic semiconductor film, this approach is applicable to any thin film material system where stratified crystalline structure and orientation can influence important interfacial processes such as charge injection and field-effect transport.

Solid-Liquid Interface Structure of Muscovite Mica in SrCl2 and BaCl2 Solutions.

The structure of the solid–liquid interface formed by muscovite mica in contact with two divalent ionic solutions (SrCl2 and BaCl2) is determined using in situ surface X-ray diffraction using both specular and non-specular crystal truncation rods. The 0.5 monolayer of monovalent potassium present at the surface after cleavage is replaced by approximately 0.25 monolayer of divalent ions, closely corresponding to ideal charge compensation within the Stern layer in both cases. The adsorption site of the divalent ions is determined to be in the surface ditrigonal cavities with minor out-of-plane relaxations that are consistent with their ionic radii. The divalent ions are adsorbed in a partly hydrated state (partial solvation sphere). The liquid ordering induced by the presence of the highly ordered crystalline mica is limited to the first 8–10 Å from the topmost crystalline surface layer. These results partly agree with previous studies in terms of interface composition, but there are significant differences regarding the structural details of these interfaces.

Crystal growth and viscous flow in barium disilicate glass

Decoupling between the diffusion coefficients that control crystal growth (DU) and viscous flow (Dη) in deeply supercooled glass-forming liquids is one of the most celebrated, still unsolved, phenomena in glass science because it strongly impacts the analysis and prediction of crystallization kinetics. To further understand the decoupling phenomenon, we measured viscosity and crystal growth rates (of the crystalline surface layer growth and internally nucleated crystals) of a supercooled liquid with barium disilicate composition. We performed all measurements using glass samples from the same batch, a rare case that we call a “clean” experiment. This type of analysis is uncommon, and its aim is to minimize the uncertainty due to the composition variation that is inherent in laboratory glass production. The decoupling temperature (Td), the glass transition temperature (Tg), the melting point (Tm), and the liquid fragility index were obtained and successfully used to test a recently derived relationship which allows one to estimate Td by knowing only Tm and the viscosity curve. We also show, for the first time, that the reduced decoupling parameter, which gauges the degree of deviation between DU and Dη, does not depend on the crystal growth mechanism for the cases of Normal or Screw Dislocation growth.

Non-lamellar lipid assembly at interfaces: controlling layer structure by responsive nanogel particles.

Biological membranes do not only occur as planar bilayer structures, but depending on the lipid composition, can also curve into intriguing three-dimensional structures. In order to fully understand the biological implications as well as to reveal the full potential for applications, e.g. for drug delivery and other biomedical devices, of such structures, well-defined model systems are required. Here, we discuss the formation of lipid non-lamellar liquid crystalline (LC) surface layers spin-coated from the constituting lipids followed by hydration of the lipid layer. We demonstrate that hybrid lipid polymer films can be formed with different properties compared with the neat lipid LC layers. The nanostructure and morphologies of the lipid films formed reflect those in the bulk. Most notably, mixed lipid layers, which are composed of glycerol monooleate and diglycerol monooleate with poly(N-isopropylacrylamide) nanogels, can form films of reverse cubic phases that are capable of responding to temperature stimulus. Owing to the presence of the nanogel particles, changing the temperature not only regulates the hydration of the cubic phase lipid films, but also the lateral organization of the lipid domains within the lipid self-assembled film. This opens up the possibility for new nanostructured materials based on lipid-polymer responsive layers.

Gradient crystalline structure induced by ultrasonic impacting and rolling and its effect on fatigue behavior of TC11 titanium alloy

Gradient crystalline structure in surface layer of TC11 titanium alloy was obtained through ultrasonic impacting and rolling process. Microstructure, work hardening state, residual stress distribution, and surface roughness in modified layer were measured and analyzed to get a comprehensive knowledge of surface characteristics. The effect of gradient crystalline surface layer on fatigue behavior was then investigated. High-cycle fatigue test results show that a considerable improvement of almost 19.3% with respect to untreated fatigue samples under the cycles of 5×106 was obtained. Obvious difference in fatigue crack source region can be found between original samples and treated series. Crack sources of all the original ones were found in surface or near-surface areas, while crack sources of all the treated ones distinctly located at near central positions. To explain this phenomenon, an in-depth discussion on the mechanism of fatigue improvement through ultrasonic impacting and rolling was performed.

Heterogeneous particle structure formation during post-crystallization of spray-dried powder

The formation of heterogeneous particle structure in skim milk powder has been investigated in a post-crystallization facility using experimental and a mathematical model. Various processing conditions were used to produce these heterogeneous structures. The experimental process parameters were used as initial and boundary conditions for the model. The modelled data agreed well with the experimental data. The experimental and modelling results show that the powder processed at high water activity (aw=0.7) with low initial moisture content (X¯0 =0.01kg/kg) developed a crystalline surface layer while the core of the particle remained amorphous. This structure is referred to as an egg-shell structure. The powder that was processed at low water activity (aw=0.1) with high initial moisture content (X¯0 =0.2kg/kg) developed a crystalline core while the surface of the particle remained amorphous. This structure is referred to as an egg-yolk structure. Understanding the dependency of particle microstructures on the processing conditions could be useful when developing procedures to control the drying equipment because the particle microstructure affects the physicochemical properties of the powder and potential applications and behaviour of the powder.