Evaporation of saline colloidal droplet and deposition pattern

The dynamic process of the evaporation and the desiccation of sessile saline colloidal droplets,and their final deposition are investigated.During the evaporation,the movement of the colloidal particles shows a strong dependence on the salt concentration and the droplet shape.The final deposition pattern indicates a weakened coffee-ring effect in this mixed droplet system.The microscopic observation reveals that as evaporation proceeds,the particle motion trail is affected by the salt concentration of the droplet boundary.The Marangoni flow,which is induced by surface tension gradient originating from the local evaporative peripheral salt enrichment,suppresses the compensation flow towards the contact line of the droplet.The inhomogeneous density and concentration field induced by evaporation or crystallization can be the major reason for various micro-flows.At last stage,the distribution and crystallization of Na Cl are affected by the colloidal particles during the drying of the residual liquid film.

Simulation Study of Heat Flux Deposition Pattern on the Surface of HT-7 Toroidal Limiters

The heat flux deposition pattern on the toroidal limiters installed in HT-7 was simulated with ANSYS code. The simulation model was established with the ripple of the magnetic field. The heat deposition pattern and temperature distribution on the surface of the toroidal linfiters were obtained. A comparison of the results obtained with and without the shaped tiles, used to reduce the heat flux on the leading edge of the limiters, was made. The maximum heat load allowed at the leading edge was about 1.8 MW/m2 because of the poor power removing capacity on the ends of the limiters. This approach can also be applied to other devices with a limiter configuration in a circular cross-section shape.

Deposition Pattern of Inosine Monophosphate( IMP) in Pig Muscle during Cold Storage

[ Objective] The paper was to investigate the degradation and deposition changes of inosine monophosphate （IMP） and its metabolites in muscle of lean pigs and crossbreeding pigs under cold storage condition at 4℃. [ Method] The contents of IMP and its metabolites in longissimus dorsi of lean pigs and crossbreeding pigs were determined by HPLC method. [ Result] Duroc, Landrace, Yorkshire and DLY pigs shared the same degradation and deposition pattern on IMP, inosine and hypoxanthine. On the second day of cold storage, the content of IMP reached the maximum value, which increased by 0.4% - 15.32% compared with the first day, and then it started to decline. On the fourth day of cold storage, the content of IMP significantly reduced by 23.81% - 39.06% than that on the second day. On the fifth and sixth day of cold storage, the content of IMP kept on falling down slowly and maintained around 1.0 mg/g. While the contents of inosine and hypoxanthine showed an increasing tendency with the extension of cold storage time. [ Conclusion ] Lean pigs Duroc, Landraee and Yorkshire and DLY three- way crossbreeding pigs shared the same degradation and deposition pattern on IMP and its metabolites. With the extension of cold storage, the content of IMP first increased then gradually decreased; while inosine and hypoxanthine gradually increased, and the difference among breeds was not significant.

Droplet Deposition Pattern Affected by Different Heating Directions

The coffee ring effect commonly exists in droplet deposition patterns,which fundamentally affects scientific research and industrial applications,like pharmaceutical purification,salt manufacturing,etc.Some researchers have tried different solutions to control the distributions of droplet deposition patterns,but most control deposits by adjusting droplet characteristics.In this work,droplet deposition patterns with different wettability are investigated by both localized and substrate heating.A whole process of droplet evaporation is recorded.The droplet generally evaporates from Constant Contact Radius(CCR)mode to Constant Contact Angle(CCA)mode,and CCR stage occupies the most of time.Experimental results show that,without any chemicals,laser induced local heating transitions particle deposition patterns from ring-like structure to dot-like patterns on a hydrophilic surface,driving most saline solvent to the center.Meanwhile,a hydrophobic surface is also investigated showing that the particles tend to assemble at the central area,but the pattern is slightly different compared to that on hydrophilic surface.In addition,physical mechanisms of local heating and heating from substrate are also explored.

Deposition pattern of drying droplets

The drying of liquid droplets is a common daily life phenomenon that has long held a special interest in scientific research.When the droplet includes nonvolatile solutes,the evaporation of the solvent induces rich deposition patterns of solutes on the substrate.Understanding the formation mechanism of these patterns has important ramifications for technical applications,ranging from coating to inkjet printing to disease detection.This topical review addresses the development of physical understanding of tailoring the specific ring-like deposition patterns of drying droplets.We start with a brief introduction of the experimental techniques that are developed to control these patterns of sessile droplets.We then summarize the development of the corresponding theory.Particular attention herein is focused on advances and issues related to applying the Onsager variational principle(OVP)theory to the study of the deposition patterns of drying droplets.The main obstacle to conventional theory is the requirement of complex numerical solutions,but fortunately there has been recent groundbreaking progress due to the OVP theory.The advantage of the OVP theory is that it can be used as an approximation tool to reduce the high-order conventional hydrodynamic equations to first-order evolution equations,facilitating the analysis of soft matter dynamic problems.As such,OVP theory is now well poised to become a theory of choice for predicting deposition patterns of drying droplets.

Infection of the Anther-smut Microbotryum violaceum in Populations of Silene dioica: Variation in Floral Morphology, Patterns of Spore Deposition and Pathogen-Pollinator Mediated Selection

The anther-smut Microbotryum violaceum ( Brandenburger and Schvinn) G. Deml. and Oberw.) causes a systematic infection of its host Silene dioica ( L.) Clairv., resulting in sterility and production of teliospores (dispersal propagules) in flowers. These spores are transmitted to healthy plants mainly by flower visitors. The behavioral responses of flower visitors to a variation in floral characters are not only likely to affect rates of pollen export/import, but also the rate of spore deposition and probability of disease. In a transplantation experiment, using plants from four different populations, we tested for correlation between variation in female floral morphology and patterns of spore and pollen deposition, and a resulting risk of disease. The source populations in this experiment were located on four islands in Skeppsvik archipelago in northern Sweden, and represented a gradient of disease incidence from completely healthy ( Island 1), low incidence ( Island 2) to high incidences ( Islands 3 and 4) of disease. Fifty plants from each population were transplanted to the center, of the population on Island 4. There were significant differences among the transplants in floral characters, i.e. corolla size, style length and ovule number. Plants from the non-diseased population had larger flowers and longer styles than plants from the highly diseased populations. Numbers of pollen grains and spores deposited on flowers were strongly and positively correlated. We found that plants originating from the non-diseased population captured approximately 4 times more pollen and 9 times more spores, per flower than die individuals from the resident population (Island 4, population 4). The incidences of disease among plants, from the four populations differed significantly, and was 37%, 20%, 18% and 0 for populations 1, 2, 3 and 4 respectively. In a survey of ten populations we found a significant negative correlation between the mean style length ( positively correlated with corolla size and ovule number) among healthy plants and incidence of disease in these populations. The potentiality for pathogen-pollinator mediated selection oil floral characters; and consequences for gone flow between populations of Silene dioica are discussed.

Changes of coastline and tidal flat and its implication for ecological protection under human activities: Take China’s Bohai Bay as an example

The change processes and trends of shoreline and tidal flat forced by human activities are essential issues for the sustainability of coastal area,which is also of great significance for understanding coastal ecological environment changes and even global changes.Based on field measurements,combined with Linear Regression(LR)model and Inverse Distance Weighing(IDW)method,this paper presents detailed analysis on the change history and trend of the shoreline and tidal flat in Bohai Bay.The shoreline faces a high erosion chance under the action of natural factors,while the tidal flat faces a different erosion and deposition patterns in Bohai Bay due to the impact of human activities.The implication of change rule for ecological protection and recovery is also discussed.Measures should be taken to protect the coastal ecological environment.The models used in this paper show a high correlation coefficient between observed and modeling data,which means that this method can be used to predict the changing trend of shoreline and tidal flat.The research results of present study can provide scientific supports for future coastal protection and management.

A NEW DRY DEPOSITION VELOCITY PATTERN AND ITS PRACTICAL APPLICATION IN HIGH RESOLUTION REGIONAL ACID DEPOSITION MODEL

A new dry deposition velocity pattern (NDDVP) for the study of region-scale dry deposition processes is developed. The mean ratio between NDDVP and 1022 experimental data of dry deposi- tion velocity V_d is 1. 06±0.82. The result shows that NDDVP is well consistent with experimental data. Practical cases are forecasted by the high resolution regional acid deposition model (EM3) with both NDDVP and old V_d pattern. The maximum ratio between the central concentrations for SO4 can reach 2.4 only due to different V_d patterns. 3-D distributions of species concentrations and dry depositions forecasted by NDDVP are better than those by the old V_d pattern.

Numerical simulation of nanoparticle pattern fabricated by electrostatic spray deposition

Electrospray deposition （ESD） as a patterning method of nanoparticles deposited on a substrate has attracted much attention due to several advantages over other methods. However, obtaining an optimum ESD processing condition for nanoparticle pattern relies much on trial experiments because of the lack of reliable numerical simulation. In this study, the deposition characteristics of nanoparticle generated by electrospray were investigated by using a three-dimensional Lagrangian model. Three important process parameters, including solution dielectric constant, applied voltage and surface charge density on mask were considered by fixing the geometrical parameters of the ESD device. Simulation result showed that under the condition of without a mask, the spray diameter increases with increasing solvent dielectric constant, and higher applied voltage makes the spray area wider. Controllability of focusing by changing surface charge density on the mask was confirmed： higher surface charge density on the mask results in more focused deposition. Validity of the numerical simulation developed in this study was verified by comnarison with exoerimental data.

Numerical investigation of a novel pattern for reducing residual stress in metal additive manufacturing

Deposition patterns can significantly affect residual stress distribution in additive manufacturing processes.In this paper,a novel pattern,the S-pattern,is proposed for the metal additive manufacturing process.The finite element method is used to study the temperature field and the stress field of a cuboid structure under the S-pattern and five other representative patterns:zig-zag,raster,alternate-line,in-out spiral,and out-in spiral.The results show that the S-pattern achieves the lowest values of both equivalent residual stress and maximum principal residual stress,and the warpage of the S-pattern is close to that of counterparts.By analyzing the temperature and stress fields under all patterns,it is found that the residual stress distribution is determined by the uniformity of temperature distribution which is correlated with the peak temperatures of corners.The equivalent residual stress and the maximum principal residual stress are inversely correlated with the average peak temperature and the minimum peak temperature of corners,respectively.These correlations between temperature and residual stress provide an effective approach to evaluate the residual stress of different patterns and guide the deposition process in practice.

Numerical simulation of micro-particle deposition in a realistic human upper respiratory tract model during transient breathing cycle

An more reliable human upper respiratory tract model that consisted of an oropharynx and four generations of asymmetric tracheo-bronchial （TB） airways has been constructed to investigate the micro-particle deposition pattern and mass distribution in five lobes under steady inspiratory condition in former work by Huang and Zhang （2011 ）. In the present work, transient airflow patterns and particle deposition during both inspiratory and expiratory processes were numerically simulated in the realistic human upper respiratory tract model with 14 cartilaginous rings （CRs） in the tracheal tube. The present model was validated under steady inspiratory flow rates by comparing current results with the theoretical models and pub- lished experimental data. The transient deposition fraction was found to strongly depend on breathing flow rate and particle diameter but slightly on turbulence intensity. Particles were mainly distributed in the high axial speed zones and traveled basically following the secondary flow. ＂Hot spots＂ of deposition were found in the lower portion of mouth cavity and posterior wall of pharynx/larynx during inspiration, but transferred to upper portion of mouth and interior wall of pharynx/larynx during expiration. The deposition fraction in the trachea during expiration was found to be much higher than that during inspiration because of the stronger secondary flow.

Low threading dislocation density in GaN films grown on patterned sapphire substrates

The growth process of three-dimensional growth mode（3D） switching to two-dimensional growth mode （2D） is investigated when GaN films are grown on cone-shaped patterned sapphire substrates by metal-organic chemical vapor deposition.The growth condition of the 3D-2D growth process is optimized to reduce the threading dislocation density（TDD）.It is found that the condition of the 3D layer is critical.The 3D layer keeps growing under the conditions of lowⅤ/Ⅲratio,low temperature,and high pressure until its thickness is comparable to the height of the cone-shaped patterns.Then the 3D layer surrounds the cone-shaped patterns and has inclined side facets and a top（0001） plane.In the following 2D-growth process,inclined side facets coalesce quickly and the interaction of TDs with the side facets causes the TDs to bend over.As a result,the TDD of GaN films can decrease to 1×10~8 cm^（-2）,giving full-width at half maximum values of 211 and 219 arcsec for（002） and（102） omega scans, respectively.

Geometrical Deposits on Microstructured Surfaces

Research into evaporating droplets on patterned surfaces has grown exponentially,since the capacity to control droplet morphology has proven to have significant technological utility in emerging areas of fundamental research and industrial applications.Here,we incorporate two interest domains-complex wetting patterns of droplets on structured surfaces and the ubiquitous coffee-ring phenomenon of nanofluids containing dispersed aluminium oxide particles.We lay out the surface design criteria by quantifying the effect of pillar density and shape on the wetting footprint of droplets,yielding complex polygon droplet geometries.Our work is not constrained to pure liquids only,as we delve into the shape selection of particle-laden droplets of different concentrations.We visualise the deposition patterns through microscopy on surfaces exhibiting different features and further establish the ordering of particles on microscale surface asperities.At a high nanofluid concentration,we observe intriguing self-assembly of particles into highly ordered intricate structures.The collective findings of this work have the potential to enhance many industrial technologies,particularly attractive for high performance optical and electrical devices.