Increase In Mesh Size Research Articles

Age, growth and mortality of the anchovy Stolephorus commersonnii (Lacepède,1803) (Clupeiformes) caught off the coast of Tanga, Tanzania

The population dynamics of Stolephorus commersonnii (Lacepède, 1803) from a ringnet fishery operating off the northern coast of Tanga Region were evaluated based on monthly length-frequency data collected from August 2016 to August 2017. The total length (TL) and total weight (TW) of 14,410 individuals ranged from 22 to 130 mm and from 0.39 to 14.64 g respectively. S. commersonnii exhibited a negative allometric growth pattern with the length-weight relationship model: W = 0.00001 x L2.886. The von Bertalanffy growth function was Lt = 86.03 x (1 – e–1.19(t – (–0.01))) using ELEFAN I from the FiSAT II software tool package. Growth performance index and longevity were estimated at (ɸ) = 3.9 and Tmax = 2.5 yrs, respectively. The total (Z), fishing (F) and natural (M) mortalities were determined at 1.39, 0.53 and 0.86 yr-1, respectively. The current exploitation rate (Ecur) was estimated at 0.38. S. commersonnii exhibited a year-round breeding pattern, with two recruitment peaks in March and June/July. Length-at-first-capture (Lc50) and length-at-first-sexual maturity (Lm50) were 40.51 and 57.35 mm TL, respectively, suggesting growth overfishing. The stock of anchovy indicates an overfishing scenario requiring management intervention such as reducing fishing effort levels, increasing mesh sizes and introducing seasonal closures during peak spawning periods.

Influence of in situ photo-induced silver nanoparticles on the ageing of acrylate materials

The present work aims to investigate the impact of a low amount of photo-induced silver nanoparticles (0.2 and 0.4 wt.% of Ag NPs) on the stability of acrylate materials (carriers of ester and ether groups) under the combined effect of oxygen and light. Different techniques were implemented to monitor the structural changes at different scales. The determination of the influence of AgNPs required a preliminary investigation of the pure acrylate polymer under the same experimental conditions. The polymer underwent a post-polymerization of the residual vinyl groups and a photo-oxidative degradation. This degradation induced chemical modifications evidenced by infrared spectroscopy and architectural changes resulting from chain scission reactions. These reactions were not only responsible for the steaming of volatile organic compounds, detected by HS-SPME/GCMS but also for the increase in mesh size controlled by thermoporosimetry.As regards the polymer/Ag NPs composite, the higher the amount of filler dispersed in the matrix, the greater the rate of degradation-. This behaviour was due to the photocatalytic effect of Ag NPs, regardless of the loading in nanoparticles. As a result of irradiation, the nanoparticles migrate to the surface of the film and coalesce, thus inducing an increase in size distribution and a gradient structuring as revealed by TEM analysis.The outcomes of this investigation are important for the development of new composite material with new functionalities (antibacterial, optical, conductive properties) for industrial applications as in textile industry.

Effects of season and mesh size on the selection of narrow-barred Spanish mackerel, Scomberomorus commerson in the Persian Gulf artisanal gillnet fishery

AbstractIn response to perceived, but unknown variation among the size selection of narrow-barred Spanish mackerel (Scomberomorus commerson) by artisanal gillnetters off Iran, and the need for such data to control exploitation as a precursor to balanced harvesting, the effects of two common mesh sizes (130 and 140 mm stretched mesh opening made from multifilament twine) on catches were investigated over one fishing year (nine months encompassing autumn to spring). Both mesh sizes mostly caught S. commerson at fork lengths (FL) larger than mean sizes at maturity (>67 cm), with the mean size selection incrementally increasing in the 130-mm mesh gillnet from autumn, and especially during spring. The greater selection occurred concurrent with an increasing condition factor (CF) among S. commerson, which typically spawn in late spring/early summer. Conversely, the relative size-selection of the 140-mm mesh gillnet decreased in spring, attributed to increasing CF precluding the capture of larger fish. Such seasonal variation in size selection might be countered by increasing mesh size to ~145 or 150 mm in spring. However, the existing 140-mm mesh might positively affect stock biomass by allowing larger, more fecund fish to avoid capture during spawning. The data support the strong influence of biological and environmental factors on gillnet size selection, which might also extend to other migratory, pelagic species.

Small steps high leaps: Bio-economical effects of changing codend mesh size in the North Sea Brown shrimp fishery

Small mesh codends applied in the brown shrimp (Crangon crangon L.) fishery in the North Sea cause large bycatch of fish, invertebrates and undersized shrimp. We investigated the most obvious and enforceable mitigation measure: the increase of mesh size beyond 20 mm, which was the medium mesh size of the fleet before 2016. The predicted selectivity from different codend designs was applied in a yield-per-recruit model able to reproduce the seasonal pattern of landings and biomass by sex, size, and age. The model enables assessment and quantifying population responses to possible management actions, also considering other influential variables such as natural mortality, which vastly decreased during the 1990s to the contemporary low level due to the decrease of cod in the Southern North Sea. Model results show that the selectivity of 20 mm codends leads to the poorest fishery and population indexes. Any increase in mesh size within the range considered and in the present low-predator situation would lead to a larger shrimp stock and higher catches. Increasing mesh size reduces catches of undersized and small commercial-sized shrimps entering the fishery mainly in summer time, thus leading to surplus catches in autumn and spring. Model results reveal that an increase of mesh size diminishes growth overfishing and allows the formation of a larger stock that may better cope a fluctuating natural mortality and the steadily upwards creeping fishing intensity.

Testing a size sorting grid in the brown shrimp (Crangon Crangon Linnaeus, 1758) beam trawl fishery

The North Sea brown shrimp (Crangon crangon Linnaeus, 1758) fishery became Marine Stewardship Council (MSC) certified in 2017. As part of the certification, the fishermen proposed to incrementally increase the mesh size of the codend used from 22 mm to 26 mm. As this increase in mesh size could result in a substantial loss of marketable sized brown shrimp (shrimp with total length equal or higher than 50 mm), a combination of a size sorting grid with a bar spacing of 6 mm and a 22 mm codend was proposed by the Danish fishermen as a possible alternative to the increase in codend mesh size. The objective of the proposed gear was to release shrimp smaller than the marketable size before they reach the codend, while potentially limiting the loss of marketable sized shrimp. Therefore, the aim of this study was to investigate the size selective performance of brown shrimp in the above-mentioned gears. The results showed that the grid reduced catches of shrimp under the marketable size of 50 mm. Moreover, the combination of the grid and a 22 mm diamond mesh codend, with an estimated L50 of 44.9 mm and a selection range of 15.6 mm, had an overall selective performance similar to that of a 26 mm diamond mesh codend, both for shrimps under and above the marketable size.

Role of rigid boundary on the decay of turbulence generated by passive-grid for free surface flow

The present study aims to investigate the flow characteristics of grid-generated turbulence under the consideration of solid boundary in free surface flow. To understand the nature of isotropy and anisotropy in the flow, the turbulent intensity is evaluated at the downstream of the grid for different mesh sizes. The energy spectrums based on the Fast Fourier and marginal Hilbert–Huang transform are presented to understand the decay of energy in the associated spectral frequency domain. It is observed that the peak of energy associated with the Fourier spectrum decreases in the near-field region of the grid with the increase in mesh size of the grid. Further, to characterise the concentrated velocity fluctuations, the paper strives to analyse the joint probability distribution function and the local intermittency measure in the close and far stream of the grid. The autocorrelation functions and the magnitude of integral length scale of the stream-wise fluctuating velocity components are also presented at two different vertical levels from the solid boundary. The normalised Shannon entropy is also evaluated to characterise the degree of the orderness or disorderness in the flow due to the interaction of grid and rigid boundary.

Research on the Effects of Roughness on the Tactile Properties of Rice Straw Particleboard Surface

To explore the effects of roughness on the tactile properties of rice straw particleboard (RSP), the surface roughness and psychological tactile and visual experiments were conducted for RSP substrates with 0.76 g/cm3 and 0.55 g/cm3 densities after sanding with sandpaper (mesh 180#, 360#, and 600#). The effects of different sandpaper types, sanding time, and density of RSP on the surface roughness were analyzed. The experimental results are as follows. The sanding treatment had significant influence on the surface roughness characterization parameters Ra and Rpv of the RSP specimens. Surface roughness differences between the 180# and 360# mesh-prepared samples were obvious. The tactile and visual psychological values of the 360# and 600# mesh-sanded specimens were higher, and the psychological quantities of untreated and 180# mesh-sanded specimens were lower. After comparing the samples with sanding treatment of sandpaper 0∼180#, the change in surface roughness of RSP with a density of 0.76 g/cm3 was smaller than that of the specimen with a density of 0.55 g/cm3. The psychological quantity difference of RSP specimens with a density of 0.55 g/cm3 was evident. When the sanding time was 1 min., the values of the roughness characterization parameters Ra and Rpv increased slightly. After 3 min. sanding, the Ra and Rpv values stabilized. When the sanding time was 5 min, the roughness was essentially unchanged. With the change in sanding time, the measured values of the tactile psychological quantity varied greatly and the measured values of the visual psychology were very close. For the RSP substrates with higher density, the surface roughness was less after sanding with a smoother surface and better tactile properties. There were significant differences between the surface roughness of the RSPs before and after sanding. After manual sanding over the same time span, the surface roughness evaluation parameter values decreased with an increase of mesh size of the sandpaper, and the tactile properties were improved. The longer the sanding time, the smaller the difference in the surface roughness parameter values, and the smaller the difference between the tactile psychological quantity and the visual psychological quantity. To expand the research scope of RSP products, this study investigates not only the physical and chemical properties but also the subjective feelings when using the RSP products. This will provide analytical methods and design guidelines for the consideration of environmental factors in furniture and interior design.

A meta-analysis of plaice size-selection data in otter trawl codends

The influence that mesh size, the number of open meshes around the circumference, twine thickness and catch size have on the size-selection of plaice (Pleuronectes platessa) in otter trawl codends is investigated by synthesising the data from 164 hauls using 25 gear configurations during 9 trips.All these variables have an effect on selection. The 50 % retention length (L50) increases by 1.9 cm for every 10 mm increase of mesh size and decreases by 0.24 cm for every doubling of catch. The selection range decreases by 3.8 % for each increase of 10 open meshes and increases by 12.3 % for each 1 mm increase of twine thickness. The mesh size and twine thickness effects have strong support from the data. The open meshes and catch size effects have less support and should be treated with some caution.There is good correspondence between the predictions of the analysis presented here and the L50 estimates of beam trawl codend selectivity trials, which is noteworthy given the many operational differences between the two fishing methods.

Large eddy simulation of high pressure spray with the focus on injection pressure

This paper presents a detailed numerical analysis of diesel engine spray structure induced by the Engine Combustion Network (ECN) Spray A at different injection pressures. The non-reacting simulations are performed using OpenFOAM where an Eulerian–Lagrangian model is adopted in the large eddy simulation (LES) framework. Effects of the LES mesh resolution as well as the spray model parameters are investigated with the focus on their impact on spray structure as the injection pressure varies. The predicted liquid and vapour penetration lengths agree well with the measurements at different injection pressures. The mixture fraction is well captured for the injection pressure of 100 and 150 MPa while a slight deviation from the measurements is observed for the injection pressure of 50 MPa near the nozzle. The parametric analysis confirms that the LES mesh resolution has significant effects on the results. A coarser mesh leads to higher liquid and vapour penetration lengths where the deviation from the measurements is larger, resulting in the highest error at the lowest injection pressure. As the mesh size increases, the droplet size distribution becomes narrower, its pick moves to the smaller droplet size and the probability of droplets with higher temperature increases. On the other hand, with increasing the mesh size, the carrier gas velocity decays slower and its radial dispersion decreases. It is found that the droplet characteristics are more affected by the mesh resolution when the injection pressure is the lowest while the opposite is true for the carrier phase. The number of Lagrangian particles also affects the droplet characteristics and the fuel-air mixing but their effects are not as significant as the mesh size. The results become less sensitive to the number of Lagrangian particles as the pressure injection decreases. Finally, the importance of the initial droplet size distribution is investigated, confirming its impact is marginal, particularly on the liquid length. It is observed that the initial droplet size is only important at very close to the nozzle and its impact on the spray structure becomes quickly insignificant due to the high rates of breakup and evaporation. This trend is consistent at different injection pressures.

Comparative study on the full-scale prediction performance of four trawl nets used in the coastal bottom trawl fishery by flume tank experimental investigation

Energy efficiency, catchability, and ecological sustainability have become important issues for coastal bottom trawl fisheries. Thus, fishing gear has been modified to increase the swept area and decrease the drag and bycatch. To evaluate the effect of twine thickness, twine material, and mesh size on the drag (bridle tension) and geometrical shape of trawl nets, this study focused on the full-scale prediction performance (geometry and resistance) of bottom trawl nets used in the coastal fishery. Four 1/18-scale bottom trawl models with different twine diameters, different mesh sizes, and even the Geometrical shape of wing-end were designed and tested in a flume tank at Tokyo University of Marine Sciences and Technology (TUMST). The flume tank experimental data were evaluated to predict full-scale performance at sea and to compare the performance of trawl nets built with traditional materials (polyethylene), namely, trawl nets 1 and 4, with those built with innovative materials (Dyneema and nylon monofilament), namely, trawl nets 2 and 3, respectively. The geometrical shape of bottom trawl net was determined from the nonlinear equation constructed and solved using the experimental data with various door spreads and towing speeds. The results show that an increase in mesh size using Dyneema (trawl net 2) systematically leads to a decrease in bridle tension ~ 34.55%, a decrease of twine diameter using nylon monofilament (trawl net 3) lead to a decrease in bridle tension ~ 35.4%, and an increase in mesh size using triangular shape in the wing-end (trawl net 4) lead to a decrease in bridle tension ~ 19.92%. The net mouth area of trawl net 1 is 4.36%, 10.88%, and 6.47% greater than those of trawl nets 2, 3, and 4, respectively. The filtered volume of trawl net 3 is 1.29%, 7.48%, and 4.13% greater than those of trawl nets 1, 2, and 4, respectively, indicating that trawl net 3 has better catch performance than other trawl nets. The shapes of floating rope of all the four trawl nets are very close with a gap of less than 1.5%, indicating that the increase in mesh size and decrease in twine diameter do not affect the geometrical shape significantly as the drag force. The results also show that the ratio between bridle tension and net mouth area of trawl net 1 is 31.57 %, 27.61%, and 14.37% greater than those of trawl nets 2, 3, and 4, respectively.

Implementation and performance study of lpCMFD acceleration method for multi-energy group k-eigenvalue neutron transport problem in hexagonal geometry

The recently developed lpCMFD acceleration scheme has been shown to be unconditionally stable and effective for SN neutron transport problems in Cartesian rectangular geometry. However, studies of lpCMFD performance for multi-energy group k-eigenvalue neutron transport problem in hexagonal geometries have not been previously investigated. In this paper, linear interpolation method on general convex polygon coarse mesh geometries is developed for lpCMFD in multi-energy group k-eigenvalue neutron transport problems. This method is tested on two hexagonal type reactor benchmark problems discretized with an equilateral triangular fine mesh for SN and different sizes of equilateral triangular and a mixed hexagonal-triangle coarse mesh grid for low order diffusion equation. It was found that lpCMFD was stable and effective for the benchmark problems investigated here with different coarse mesh grids, while CMFD became unstable when coarse mesh size increases. pCMFD was found to be stable in all configurations but was generally slower or as effective as lpCMFD and CMFD. The barycentric interpolation technique developed in this paper for lpCMFD in 2D hexagonal geometry is demonstrated to be effective and can be applied in realistic practical problems.

Cumulative selectivity benefits of increasing mesh size and using escape gaps in Australian Portunus armatus traps

AbstractThe individual and cumulative effects of increasing mesh size (from 56‐ to 75‐mm stretched mesh opening) and installing three escape gaps (36 × 120 mm) in collapsible‐netted round traps were assessed to address concerns associated with excessive discarding in an Australian portunid fishery. Compared to conventional traps comprising 56‐mm mesh throughout, those with the same mesh size and escape gaps caught significantly fewer (by 54%) undersized blue swimmer crabs, Portunus armatus Milne‐Edwards and yellowfin bream, Acanthopagrus australis Günther (by 64%). Irrespective of escape gaps, simply increasing the mesh size to 75 mm did not significantly affect catches of undersized P. armatus, although 87% fewer A. australis were retained. Traps with both 75‐mm mesh and escape gaps maintained reductions of A. australis, but had a clear cumulative effect on P. armatus selection, retaining 84% fewer undersized individuals across a larger size at retention. The results support using escape gaps in existing conventional traps, but illustrate the need to configure the minimum legal mesh size to approach the desired target size of P. armatus as a precursor to maximising trap selectivity. Larger‐meshed traps also require less material (i.e. plastic), which benefits their manufacture and, equally importantly, reduces environmental costs when lost.

Effects of micro-, meio- and macroinvertebrates associated with burial on the decomposition of an aquatic macrophyte (Vallisneria natans) in a eutrophic shallow lake in China

Aquatic invertebrates play an important role in plant decomposition. However, little information is available regarding the relative importance of micro-, meio- and macroinvertebrates in this process, particularly their role in the decomposition of buried organic matter. To investigate the role of these invertebrates in the decomposition of the aquatic macrophyte Vallisneria natans, leaves of V. natans were placed in litterbags with four different mesh sizes (0.025, 0.042, 0.5 and 5mm) and the bags were either incubated at the sediment–water (SW) interface or buried at a depth of 10cm (B10) for 60 days in Lake Nanhu, China, in July 2015. Increased mesh size significantly increased the loss of plant mass. The decomposition rate ranged from 0.0173 to 0.0467day–1 in the SW treatment, and from 0.0083 to 0.0280day–1 in the B10 treatment. Excluding microinvertebrates, burial significantly affected microbial respiration and invertebrate abundance. Increased mesh size increased invertebrate abundance and richness, but did not significantly affect microbial respiration in either treatment. The average contribution of micro-, meio- and macroinvertebrates and microbes to plant mass loss in the SW treatment was 23.1, 13.5, 7.0 and 56.5% respectively, compared with 19.7, 24.5, 12.3 and 43.5% respectively in the B10 treatment. The results of this study reveal the important but underestimated role of micro- and meioinvertebrates in macrophyte decomposition.

Shrimp trap selectivity in a Mediterranean small-scale-fishery

Small-scale shrimp trap fisheries, which have received very little attention in areas with limited potential for economic diversification, could offer a sustainable and socially beneficial option for profitable businesses in these regions. This study explores the effect of mesh size on selectivity of the commercially important narwal shrimp, Plesionika narval, in the Mediterranean Sea. Three different mesh sizes (8 × 8, 12 × 12 and 12 × 25 mm) were tested in fishing trials, with a theoretical Minimum Landing Size (MLS) using a defined maturity size of 12 mm to support interpretation of the results. Using the retention rates and the estimations on population fractions above and below MLS, we show that the use of the smallest- and largest-sized meshes would not support sustainable or efficient fishery. The results demonstrate a significant decrease in capture probability of undersized narwal shrimps with increased mesh size. The medium-sized mesh traps prove to be the best compromise for the fishery with high catch efficiency of commercial size shrimp and a low capture probability of undersized individuals. The results outlined in this article could be used to develop management plans for small-scale trap fisheries as a basis for developing viable enterprises in remote coastal communities.

First Assessment of the Thryssa vitrirostris (Engraulidae) Beach Seine Fishery in Northeastern Mozambique

Monthly length-frequency data, from 2009 to 2014, was used to estimate the growth parameters, mortality, and spawning season, and to assess the exploitation status of Thryssa vitrirostris (Engraulidae) fisheries in Pebane. The von Bertalanffy asymptotic length (L∞) and growth rate (K) were 25.1 cm (standard length) and 0.41 per year (standard length), respectively. Two proxy recruitment peaks were found: the first peak of recruitment occurs from April to July, and the second recruitment peak from September to October. The total estimated mortality rates (Z), natural mortality (M), and fishing mortality (F) were Z = 1.31, M = 0.92, and F = 0.39. For the beach seine gear, the size at first catch of T. vitrirostris was Lc25 = 4.43 cm. The 50% retention size of the catch was Lc50 = 5.39 cm. The retention probability analyses revealed a large rate of juvenile fishing mortality (54.2%). The estimated exploitation rate (0.30) was below the maximum exploitation rate (0.48), and above the optimal sustainable exploitation rate (E50 = 0.28), evidencing a sustainable fishery. However, under such an exploitation regime, it is advised that a continuously monitoring-survey of T. vitrirostris is maintained. An increase in migration of fishermen has been recently recorded in Pebane, due to its rich fisheries, which can increase the fishing effort and the risk of overexploitation if management measures (such as mesh size increase) are not taken in advance.

SELETIVIDADE DE REDES DE EMALHAR PARA PEIXES FORRAGEIROS COM í­Å NFASE PARA Opisthonema oglinum EM UM ESTUÁRIO DO NORDESTE DO BRASIL

As seletividades de redes de emalhar para peixes forrageiros que habitam o Canal de Santa Cruz (PE, Brasil) foram estimadas a partir de um experimento com três tamanhos de malha (30, 40 e 50 mm). O SELECT foi usado para estimar as curvas de retenção através de quatro modelos: normal com dispersão fixa, normal com dispersão variável, lognormal e gama. No total foram identificadas 28 espécies. Os parí­¢metros de seletividade foram estimados para as espécies Opisthonema oglinum, Anchovia clupeoides e Cetengraulis edentulus. O modelo normal com dispersão variável foi de melhor ajuste para todas as espécies. No caso da pesca da O. oglinum no Canal de Santa Cruz verificou-se que as quantidades capturadas de indiví­­duos jovens são particularmente mais expressivas na rede de emalhar com a malha de 30 mm. No entanto, um eventual aumento da malha indica um desvio pouco significativo da estrutura de comprimento da captura para maiores tamanhos, mas as capturas certamente seriam reduzidas. Assim, regulamentações com aumento de malha devem resultar em inviabilidade da continuidade da pesca com diminuição das capturas.

About impedance spectra and dynamics of charge carriers in neat poly(ethylene oxide) structures

Impedance spectra of linear and cross-linked poly(ethylene oxide) (PEO) are analyzed in a wide range of temperature. Dielectric responses differ at low and high temperature due to tendency of PEO to crystallization below melting temperature. Extent of crystallization depends on cross-linking density. The network in PEO with high cross-linking density is rigid and morphology transition shifts to very low temperature. Debye-like relaxation appears at low temperature similar as in ionic liquids. Onset of polarization relaxation shifts to higher temperature with increasing mesh size that is coupling of electric and structural relaxation appears. This is also nicely reflected by scaled conductivity. It demonstrates that the structure in cross-linked systems is a superposition of chemical and physical networks. They relax separately at low temperature and frequency under condition of sufficient rigidity.

Stress relaxation at a gelatin hydrogel–glass interface in direct shear sliding

In this paper, we study experimentally the stress relaxation behavior of soft solids such as gelatin hydrogels on a smooth glass surface in direct shear sliding. It is observed experimentally that irrespective of pulling velocity, the sliding block relaxes to the same level of nonzero residual stress. However, residual stress increases with increasing gelatin concentration in the hydrogels. We have also validated a friction model for strong bond formation during steady relaxation in light of the experimental observations. Our theoretical analysis establishes that population of dangling chains at the sliding interface significantly affects the relaxation process. As a result, residual stress increases with increasing gelatin concentration or decreasing mesh size of the three-dimensional structures in the hydrogels. It is also found that the transition time, at which a weak bond converts to strong bond, increases with increasing mesh size of the hydrogels. Moreover, relaxation time constant of a strong bond decreases with increasing mesh size. However, activation length of a strong bond increases with mesh size. Finally, this study signifies the role of residual strength in frictional shear sliding and it is believed that these results should be useful to understand the role of residual stress in stick-slip instability.

Embedding of polytopes for topology optimization

A methodology for solving three-dimensional topology optimization problems through a two-level mesh representation approach is described and evaluated. Structural topology optimization problems are executed on a polytope-based mesh, which carries the design variable (and subsequently the density). Displacement field is determined using tetrahedron elements, embedded within the polytopes. The proposed mapping-based framework decouples the analysis routine and optimization algorithm from the specific choice of topology optimization formulation. The mapping-based formulation allows easy applicability of features such as regularization and density filters and symmetry through a mapping matrix. The embedding approach is demonstrated on minimum compliance problems and solid–void solution is obtained by employing continuation on the solid isotropic material with penalization penalty parameter. We show that the proposed approach is able to achieve solutions free of numerical anomalies (e.g., checkerboard pattern and one-node connections) without the application of any explicit regularization scheme nor filtering. Our solutions approach the theoretical solution as mesh size increases.

Synthesis and Characterisation of Photocrosslinked poly(ethylene glycol) diacrylate Implants for Sustained Ocular Drug Delivery

PurposeTo investigate the sustained ocular delivery of small and large drug molecules from photocrosslinked poly(ethylene glycol) diacrylate (PEGDA) implants with varying pore forming agents.MethodsTriamcinolone acetonide and ovalbumin loaded photocrosslinked PEGDA implants, with or without pore-forming agents, were fabricated and characterised for chemical, mechanical, swelling, network parameters, as well as drug release and biocompatibility. HPLC-based analytical methods were employed for analysis of two molecules; ELISA was used to demonstrate bioactivity of ovalbumin.ResultsRegardless of PEGDA molecular weight or pore former composition all implants loaded with triamcinolone acetonide released significantly faster than those loaded with ovalbumin. Higher molecular weight PEGDA systems (700 Da) resulted in faster drug release of triamcinolone acetonide than their 250 Da counterpart. All ovalbumin released over the 56-day time period was found to be bioactive. Increasing PEGDA molecular weight resulted in increased system swelling, decreased crosslink density (Ve), increased polymer-water interaction parameter (χ), increased average molecular weight between crosslinks (Mc) and increased mesh size (ε). SEM studies showed the porosity of implants increased with increasing PEGDA molecular weight. Biocompatibility showed both PEGDA molecular weight implants were non-toxic when exposed to retinal epithelial cells over a 7-day period.ConclusionPhotocrosslinked PEGDA implant based systems are capable of controlled drug release of both small and large drug molecules through adaptations in the polymer system network. We are currently continuing evaluation of these systems as potential sustained drug delivery devices.