Duration Of Attachment Research Articles

The structural and functional effects of myosin regulatory light chain phosphorylation are amplified by increases in sarcomere length and [Ca2+

Precise regulation of sarcomeric contraction is essential for normal cardiac function. The heart must generate sufficient force to pump blood throughout the body, but either inadequate or excessive force can lead to dysregulation and disease. Myosin regulatory light chain (RLC) is a thick-filament protein that binds to the neck of the myosin heavy chain. Post-translational phosphorylation of RLC (RLC-P) by myosin light chain kinase is known to influence acto-myosin interactions, thereby increasing force production and Ca2+-sensitivity of contraction. Here, we investigated the role of RLC-P on cardiac structure and function as sarcomere length and [Ca2+] were altered. We found that at low, non-activating levels of Ca2+, RLC-P contributed to myosin head disorder, though there were no effects on isometric stress production and viscoelastic stiffness. With increases in sarcomere length and Ca2+-activation, the structural changes due to RLC-P become greater, which translates into greater force production, greater viscoelastic stiffness, slowed myosin detachment rates and altered nucleotide handling. Altogether, these data suggest that RLC-P may alter thick-filament structure by releasing ordered, off-state myosin. These more disordered myosin heads are available to bind actin, which could result in greater force production as Ca2+ levels increase. However, prolonged cross-bridge attachment duration due to slower ADP release could delay relaxation long enough to enable cross-bridge rebinding. Together, this work further elucidates the effects of RLC-P in regulating muscle function, thereby promoting a better understanding of thick-filament regulatory contributions to cardiac function in health and disease. KEY POINTS: Myosin regulatory light chain (RLC) is a thick-filament protein in the cardiac sarcomere that can be phosphorylated (RLC-P), and changes in RLC-P are associated with cardiac dysfunction and disease. This study assesses how RLC-P alters cardiac muscle structure and function at different sarcomere lengths and calcium concentrations. At low, non-activating levels of Ca2+, RLC-P contributed to myofilament disorder, though there were no effects on isometric stress production and viscoelastic stiffness. With increases in sarcomere length and Ca2+-activation, the structural changes due to RLC-P become greater, which translates into greater force production, greater viscoelastic stiffness, slower myosin detachment rate and altered cross-bridge nucleotide handling rates. This work elucidates the role of RLC-P in regulating muscle function and facilitates understanding of thick-filament regulatory protein contributions to cardiac function in health and disease.

Experimental evidence supports the ability of spotted lanternfly to hitchhike on vehicle exteriors as a mechanism for anthropogenic dispersal.

Historically, anecdotal observations support the likelihood of human-assisted invasive insect dispersal to new environments. No previous studies have investigated the ability of insects to remain attached to moving vehicles; however, such information is critical for prioritizing research, mitigation activities and understanding anthropogenic effects on biotic communities. Lycorma delicatula (White), spotted lanternfly (SLF), an invasive insect whose range is currently expanding throughout the United States, is commonly observed in urban settings and near transportation hubs. We developed a novel method to test SLF's ability to remain on vehicle surfaces including bonnet, nose wing, windscreen, wipers and scuttle panel using laminar wind flow from 0 to 100 ± 5 km h-1. We found all mobile life stages (nymphs and adults) could remain on the vehicle up to 100 km h-1. First instar nymphs and early season adults remained attached at significantly higher wind speeds than other stages. A brief acclimatization period prior to wind delivery increased attachment duration for all life stages except later season adults. The importance of outliers in the success of invasive species is well established. Given these results, any hitchhiking SLF could potentially establish incipient populations. This methodology will be beneficial for exploring human-assisted dispersal of other invasive arthropods.

Comparative Responses of Orange-Foot and Common-Foot Haliotis gigantea to Carotenoid-Enriched Diets: Survival, Heat Tolerance, and Bacterial Resistance.

Carotenoids, known to enhance survival, heat tolerance, and bacterial resistance, play an essential role in the nutrition of economically important aquatic animals. This study specifically examined their impact as feed additives on the abalone Haliotis gigantea. We prepared 13 compound feeds with varying levels of astaxanthin, zeaxanthin, and β-carotene, and administered them to both common-footed and orange-footed H. gigantea. The survival rate of H. gigantea was about 70-80%, with no significant differences in survival observed among the various carotenoid-supplemented feeding groups or when compared with the control group, nor between orange-footed and common-footed individuals. In heat attachment duration experiments, orange-foot abalones exhibited longer attachment durations with certain concentrations of astaxanthin and zeaxanthin, whereas common-foot abalones showed extended durations with astaxanthin, zeaxanthin, and β-carotene, indicating that common-foot abalones might benefit more from these carotenoids. Additionally, our results showed similar patterns and levels of Vibrio harveyi AP37 resistance in both orange-footed and common-footed H. gigantea, suggesting a uniform response to carotenoid supplementation in their bacterial defense mechanisms. This study suggests the potential benefits of carotenoid supplementation in H. gigantea and contributes to the theoretical basis for developing high-quality artificial compound feeds.

Origin of tradeoff between movement velocity and attachment duration of kinesin motor on a microtubule

Kinesin-1 motor protein is a homodimer containing two identical motor domains connected by a common long coiled-coil stalk via two flexible neck linkers. The motor can step on a microtubule with a velocity of about 1 μm⋅s−1 and an attachment duration of about 1 s under physiological conditions. The available experimental data indicate a tradeoff between velocity and attachment duration under various experimental conditions, such as variation of the solution temperature, variation of the strain between the two motor domains, and so on. However, the underlying mechanism of the tradeoff is unknown. Here, the mechanism is explained by a theoretical study of the dynamics of the motor under various experimental conditions, reproducing quantitatively the available experimental data and providing additional predictions. How the various experimental conditions lead to different decreasing rates of attachment duration versus velocity is also explained.

Evaluating the Effectiveness of Intravenous Ozonated Normal Saline in the Treatment of Severe COVID-19 Disease: A randomized control trial

Background: There is still no specific treatment strategy for COVID-19 other than supportive management. The potential biological benefits of ozone therapy include reduced tissue hypoxia, decreased hypercoagulability, modulated immune function by inhibiting inflammatory mediators, improved phagocytic function, and impaired viral replication. This study aimed to evaluate the effect of intravenous ozonated normal saline on patients with severe COVID-19 disease. Methods: In this study, a single centralized randomized clinical trial was conducted on 80 hospitalized patients with severe COVID-19. The patients were selected by random allocation method and divided into two groups A and B. In group A (control group), patients were given standard drug treatment, and in group B (intervention group), patients received ozonated normal saline in addition to the standard drug treatment. In the intervention group, 400 mL of normal saline was weighed by 40 μg/ kg of body weight and was injected into patients within 15 to 30 minutes (80 to 120 drops per minute). This process was done daily every morning for a week. Primary and secondary outcomes of the disease included changes in the following items: length of hospital stay, inflammatory markers including C-reactive protein (CRP), clinical recovery, arterial blood oxygen status, improvement of blood disorders such as leukopenia and leukocytosis, duration of ventilator attachment, and rapid clearance of lung lesions on CT scans. The need for intensive care unit (ICU) hospitalization, the length of ICU stay, and the mortality rate in patients of the two groups was compared. Results: According to the results of the initial outcome variable analysis, the probability of discharge of patients who received the normal ozonated saline intervention was 33% higher than patients who did not receive this intervention; however, this relationship was not statistically significant (HR=0.67, 95%, CI=0.42-1.06, P value=0.089). The chance of ICU hospitalization in patients of the intervention group was three times more than that of the comparison group, but this relationship was not significant (odds ratio=4.4 95% CI=1.32-14.50, P value=0.016). The use of ozonated normal saline was found to increase the risk of death by 1.5 times but this relationship was not statistically significant (odds ratio=1.5, 95% CI=.24-9.75, P value=0.646). Ozonated normal saline had a significant effect on changes in respiration rate (in the intervention group the number of breaths was decreased) and the erythrocyte sedimentation rate (in the intervention group the erythrocyte sedimentation rate was increased); however, it had no significant effect on other indicators. Conclusion: The present study showed that ozone therapy in hospitalized patients with severe COVID-19 could help improve some primary and secondary outcomes of the disease. Governments and health policymakers should make ozone therapy an available care service so that the need for advanced treatment facilities decreases; consequently, this measure may improve patient safety, prevent lung tissue destruction, and control cytokine storms in patients. Additionally, health decision-makers need to aim for the effective clinical improvement of patients, especially severe ones, and the reduction of their mortality. However, further large-scale multicenter studies with larger sample sizes considering drug side effects and other variables influencing the clinical course of COVID-19 can provide more information on the effectiveness and importance of ozone therapy.

Design and Testing of a Superelastic Nitinol Tissue Attachment Mechanism for Long-Term Gastrointestinal Device Retention

AbstractIngestible devices have become a popular means for diagnosing and treating the gastrointestinal (GI) tract due to their noninvasive nature. However, their residency period in the GI tract is limited by the transit time through it. In previous work, we designed a tissue attachment mechanism (TAM) inspired by parasitic worms' attachment methods, which were tested for implanting biosensors or drug delivery payloads to the small intestine with a swallowable capsule robot. In that work, the attachment success rate was 91.7%, and the average attachment duration of the TAM was 32.2 h after factorial optimization of major design factors. This work develops a novel nitinol TAM (NTAM) for improving the attachment duration using the shape-changing properties of nitinol. The attachment strength of the NTAM to the intestinal tissue was assessed both ex vivo and in vivo. The attachment duration of the NTAMs in live porcine models was evaluated from radiographic images, and histological analysis of the attachment location of an NTAM was performed after euthanasia. The NTAM was 100% successful in an attachment strength study and achieved a maximum attachment duration of 13 days, while the average attachment duration was 85.63 ± 77.83 h. Histological analysis did not report any permanent damage to the tissue. This work shows a 2.7-fold improvement in attachment duration over the previous design. This work has demonstrated a method of prolonged attachment to the intestinal wall through a swallowable device, which can be used for long-term drug delivery or biosensing.

Year-round tick exposure of dogs and cats in Germany and Austria: results from a tick collection study

BackgroundTicks and tick-borne diseases play a major role in companion animal health. Additionally, the European tick fauna is changing, for instance due to the spread of Dermacentor reticulatus, displaying a higher likelihood of winter activity than Ixodes ricinus. Therefore, we investigated current tick infestations in dogs and cats in Germany and in parts of Austria and the seasonal infestation risk.MethodsOverall, 219 veterinary practices were invited to collect ticks from cats and dogs on a monthly basis. Ticks were morphologically identified and female I. ricinus specimens were measured to estimate attachment duration.ResultsIn total, 19,514 ticks, 17,789 (91.2%) from Germany and 1506 (7.7%) from Austria, were received between March 2020 and October 2021, with 10,287 specimens (52.7%) detached from dogs, 8005 from cats (41.0%) and 1222 from other species (6.3%). In Germany, the most common tick species collected from dogs were I. ricinus (78.0%) and D. reticulatus (18.8%), while cats mainly harboured I. ricinus (91.3%) and I. hexagonus (5.5%) and only few D. reticulatus (0.6%). In Austria, collected I. ricinus reached similar proportions in dogs (90.4%) and cats (95.3%), followed by D. reticulatus in both dogs (5.2%) and cats (1.5%), with I. hexagonus (0.9%) collected only marginally from cats. The average infestation intensity amounted to 1.62 ticks/dog and 1.88 ticks/cat. The single to multiple infestation ratio was 79.1% to 20.9% in dogs and 69.0% to 31.0% in cats, with cats being significantly more often multiple infested than dogs, while the proportion of mixed-species infestations was 2.0% for both dogs and cats. The average attachment duration of female I. ricinus specimens amounted to 78.76 h for dogs and 82.73 h for cats. Furthermore, year-round tick exposure was confirmed, with 108 D. reticulatus and 70 I. ricinus received on average per month during December 2020 to February 2021.ConclusionsThe study shows a year-round tick infestation risk, with activity of both D. reticulatus and I. ricinus during winter, and confirms the widespread occurrence of D. reticulatus in Germany. Additionally, long average attachment durations and frequent multiple infestations underline the need for adequate year-round tick control, even during the winter months.Graphical

KIF1A is kinetically tuned to be a superengaging motor under hindering loads

KIF1A is a highly processive vesicle transport motor in the kinesin-3 family. Mutations in KIF1A lead to neurodegenerative diseases including hereditary spastic paraplegia. We applied optical tweezers to study the ability of KIF1A to generate and sustain force against hindering loads. We used both the three-bead assay, where force is oriented parallel to the microtubule, and the traditional single-bead assay, where force is directed along the radius of the bead, resulting in a vertical force component. The average force and attachment duration of KIF1A in the three-bead assay were substantially greater than those observed in the single-bead assay. Thus, vertical forces accelerate termination of force ramps of KIF1A. Average KIF1A termination forces were slightly lower than the kinesin-1 KIF5B, and the median attachment duration of KIF1A was >10-fold shorter than KIF5B under hindering loads. KIF1A rapidly reengages with microtubules after detachment, as observed previously. Strikingly, quantification enabled by the three-bead assay shows that reengagement largely occurs within 2ms of detachment, indicating that KIF1A has a nearly 10-fold faster reengagement rate than KIF5B. We found that rapid microtubule reengagement is not due to KIF1A's positively charged loop-12; however, removal of charge from this loop diminished the unloaded run length at near physiological ionic strength. Both loop-12 and the microtubule nucleotide state have modulatory effects on reengagement under load, suggesting a role for the microtubule lattice in KIF1A reengagement. Our results reveal adaptations of KIF1A that lead to a model of superengaging transport under load.

Career Satisfaction of Malaysian Dentists With Expanded Roles at a Specialist Clinic

Public dentists interested in postgraduate studies were required to complete clinical attachments at the Malaysian Ministry of Health (MOH) Dental Specialist Clinic (DSC). This cross-sectional quantitative study aimed to explore career satisfaction (CS) and barriers perceived by Malaysian dentists at Malaysia's MOH DSC. A total of 208 dentists from DSC nationwide completed an online questionnaire in June 2022. Demographic data and information on dentists' expanded roles were retrieved. Responses on dentists' satisfaction and perceived barriers were collected using a 5-point ordinal scale. Mann-Whitney U and Kruskal-Wallis tests were used to compare the mean rank differences for CS. Factors influencing CS were analysed using multiple logistic regression (MLR) (P < .05). The mean age of the respondents was 32.68 ± 2.48 years. Almost half (49.0%) of the respondents were attached to a non-hospital-based clinic. The majority (72.0%) of them were permanently attached to the DSC. About half of the dentists (51.0%) strongly agreed that they received no financial incentives for their expanded role at the MOH DSC. Dentists attached at a non-hospital-based clinic (P=.046), working with more than 15 years of experience (P=.013), and having 12 to 18 months' duration of attachment (P=.014) were more satisfied. MLR analysis revealed that non-Malay respondents (odds ratio [OR], 1.54; P=.035) and those who applied for scholarships more than 3 times (OR, 1.85; P=.050) were more satisfied. In contrast, more than 19 months at the DSC decreased CS (OR, 0.44; P=.029). Despite having a similar organisational structure, DSC dentists had different satisfaction levels. Dentists' ethnicity, duration of attachment, and frequency of applying for scholarships influenced their CS. Future career advancement plans in the MOH should consider these important influencing factors to ensure the delivery of quality health care from their personnel.

The movement and settlement behaviour of cyprids of Balanus reticulatus on the surfaces of the titanium alloys

The motion paths of Balanus reticulatus cyprids were similar on all the titanium alloys surfaces. On the parallel grinding surfaces, the temporary attachment duration and the settlement ratio of the cyprids were influenced by the roughness and the composition of the surfaces and correlated positively. The surface roughness could also change the contact area and the numbers of the attachment points of the cyprids in the similar pattern. Consequently, the roughness and the composition of the surfaces regulated the cyprid settlement by the temporary attachment duration. The cross grinding increased the temporary attachment duration but drastically decreased the settlement ratio to 0 compared to the parallel grinding, possibly due to the voids and the drastic decrease of the contact area and the numbers of the attachment points of the cyprids on the cross grinding surface, respectively. The cross grinding therefore significantly reduced the cyprid settlement compared to the parallel grinding.

Effects of omecamtiv mecarbil on the contractile properties of skinned porcine left atrial and ventricular muscles.

Omecamtiv mecarbil (OM) is a novel inotropic agent for heart failure with systolic dysfunction. OM prolongs the actomyosin attachment duration, which enhances thin filament cooperative activation and accordingly promotes the binding of neighboring myosin to actin. In the present study, we investigated the effects of OM on the steady-state contractile properties in skinned porcine left ventricular (PLV) and atrial (PLA) muscles. OM increased Ca2+ sensitivity in a concentration-dependent manner in PLV, by left shifting the mid-point (pCa50) of the force-pCa curve (ΔpCa50) by ∼0.16 and ∼0.33 pCa units at 0.5 and 1.0 μM, respectively. The Ca2+-sensitizing effect was likewise observed in PLA, but less pronounced with ΔpCa50 values of ∼0.08 and ∼0.22 pCa units at 0.5 and 1.0 μM, respectively. The Ca2+-sensitizing effect of OM (1.0 μM) was attenuated under enhanced thin filament cooperative activation in both PLV and PLA; this attenuation occurred directly via treatment with fast skeletal troponin (ΔpCa50: ∼0.16 and ∼0.10 pCa units in PLV and PLA, respectively) and indirectly by increasing the number of strongly bound cross-bridges in the presence of 3 mM MgADP (ΔpCa50: ∼0.21 and ∼0.08 pCa units in PLV and PLA, respectively). It is likely that this attenuation of the Ca2+-sensitizing effect of OM is due to a decrease in the number of “recruitable” cross-bridges that can potentially produce active force. When cross-bridge detachment was accelerated in the presence of 20 mM inorganic phosphate, the Ca2+-sensitizing effect of OM (1.0 μM) was markedly decreased in both types of preparations (ΔpCa50: ∼0.09 and ∼0.03 pCa units in PLV and PLA, respectively). The present findings suggest that the positive inotropy of OM is more markedly exerted in the ventricle than in the atrium, which results from the strongly bound cross-bridge-dependent allosteric activation of thin filaments.

A Factorial Approach for Optimizing the Design Parameters of a Tissue Attachment Mechanism for Drug Delivery.

Biological macromolecule drugs or biologics are not suited for commonly preferred oral delivery due to their intrinsic instability and physical, chemical, or immunological barriers to the gastrointestinal tract. Ingestible capsule robots (ICR) have become a versatile platform, including use for drug delivery applications for various gastrointestinal pathologies with future potential for systemic drug delivery. In this work, a tissue attachment mechanism (TAM) for a drug delivery ICR is introduced that can facilitate a non-invasive systemic delivery of unaltered biologics via direct injection through the insensate layers of the small intestine. The main prerequisite for achieving systemic drug delivery via this device is to have a strong tissue attachment of the TAM. This study aimed to optimize the attachment success rate for drug delivery and characterize attachment duration in vivo. A fractional factorial approach was used in vivo to identify and optimize factors that most influence attachment of the TAM to maximize attachment rate. Multiple in vivo optimization levels were performed using the small intestine of anesthetized pigs, and an attachment success rate of 92% was achieved. Optimal TAMs were surgically placed in vivo to determine the duration of attachment following anesthetization and surgery recovery. The average in vivo attachment duration was 32.2±9.4 hours. This work establishes a device for consistent and reliable attachment duration, making the TAM a suitable candidate for a 24-hour systemic drug delivery platform.

Comparison Of Treatment Effects Of Dental Preparations For Reducing Dental Sensitivity

The symptom of increased sensivity of enamels in the examined patients,from 18 to 30 years,was the pain that occurred under the influence of thermal,chemical or mechanical stimuli ang independently passing after some time. The duration of the pain attachment depended on the degree and localization of damage to the dental enamel.

Effect of Metals on Underwater Adhesion of Gastropod Adhesive Mucus.

Many gastropods release mucus hydrogels, which help them to remain attached to different substrates. Although not as strong as synthetic or biomimetic adhesives, some of these hydrogels have the ability to adhere to wet surfaces. These complex hydrogels mainly consist of proteins and carbohydrates, their natural cross-linking reactions being dependent on the presence of metals. In this paper, we investigated the role of metals in improving the underwater adhesive property of the mucus hydrogel from the slug Laevicaulis alte. We found that the strength and duration of attachment of two glass surfaces under water by the mucus hydrogel could be enhanced by its simple treatment with salts of metals, namely, Ca, Mg, Cu, or Zn. The degree of enhancement followed the order Ca2+ < Mg2+ < Zn2+ < Cu2+. The Cu2+-treated hydrogel kept two glass surfaces attached under water for about 20 days, while Zn2+ treatment caused attachment for about 15 days, as compared to the 3–5 days of attachment caused by the untreated gel. Treatment with both metals increased the underwater stability of the hydrogel almost threefold, presumably by strengthening its cross-linking. However, the Cu2+-treated hydrogel fell short of its adhesive function in the case of fast attachment within time scale of minutes, showing considerably low adhesive strength. From this study, we conclude that the treatment with Zn2+ is the best choice for improvement of the underwater adhesive property in terms of strength and stability. Overall, this work presents a novel biological underwater adhesive. The dynamic behavior of this multicomponent hydrogel in a versatile metal-rich environment may guide us toward designing new useful biomimetics.

Movement ecology of black marlin Istiompax indica in the Western Indian Ocean.

The black marlin Istiompax indica is an apex marine predator and is susceptible to overfishing. The movement ecology of the species remains poorly known, particularly within the Indian Ocean, which has hampered assessment of their conservation status and fisheries management requirements. Here, we used pop‐up archival satellite tags to track I. indica movement and examine their dispersal. Forty‐nine tags were deployed off Kenya during both the north‐east (November–April) and south‐west (August–September) monsoon seasons, providing locations from every month of the year. Individual I. indica were highly mobile and track distance correlated with the duration of tag attachment. Mean track duration was 38 days and mean track distance was >1800 km. Individuals dispersed in several directions: north‐east into Somalian waters and up to northern Oman, east towards the Seychelles, and south into the Mozambique Channel. Their core habitat shifted seasonally and overlapped with areas of high productivity off Kenya, Somalia and Oman during the first half of the year. A second annual aggregation off the Kenyan coast, during August and September, did not coincide with high chlorophyll‐a (chl‐a) concentrations or thermal fronts, and the drivers of the species' presence and movement from this second aggregation was unclear. We tested their habitat preferences by comparing environmental conditions at track locations to the conditions at locations along simulated tracks based on the empirical data. Observed I. indica preferred cooler water with higher chl‐a concentrations and stayed closer to the coast than simulated tracks. The rapid and extensive dispersal of I. indica from Kenya suggests that there is likely a single stock in the Western Indian Ocean, with individuals swimming between areas of high commercial catches off northern Somalia and Oman, and artisanal and recreational fisheries catches throughout East Africa and Mozambique.

Myosin cross-bridge kinetics slow at longer muscle lengths during isometric contractions in intact soleus from mice.

Muscle contraction results from force-generating cross-bridge interactions between myosin and actin. Cross-bridge cycling kinetics underlie fundamental contractile properties, such as active force production and energy utilization. Factors that influence cross-bridge kinetics at the molecular level propagate through the sarcomeres, cells and tissue to modulate whole-muscle function. Conversely, movement and changes in the muscle length can influence cross-bridge kinetics on the molecular level. Reduced, single-molecule and single-fibre experiments have shown that increasing the strain on cross-bridges may slow their cycling rate and prolong their attachment duration. However, whether these strain-dependent cycling mechanisms persist in the intact muscle tissue, which encompasses more complex organization and passive elements, remains unclear. To investigate this multi-scale relationship, we adapted traditional step-stretch protocols for use with mouse soleus muscle during isometric tetanic contractions, enabling novel estimates of length-dependent cross-bridge kinetics in the intact skeletal muscle. Compared to rates at the optimal muscle length (Lo), we found that cross-bridge detachment rates increased by approximately 20% at 90% of Lo (shorter) and decreased by approximately 20% at 110% of Lo (longer). These data indicate that cross-bridge kinetics vary with whole-muscle length during intact, isometric contraction, which could intrinsically modulate force generation and energetics, and suggests a multi-scale feedback pathway between whole-muscle function and cross-bridge activity.

Variable Seepage Meter Efficiency in High-Permeability Settings

The efficiency of seepage meters, long considered a fixed property associated with the meter design, is not constant in highly permeable sediments. Instead, efficiency varies substantially with seepage bag fullness, duration of bag attachment, depth of meter insertion into the sediments, and seepage velocity. Tests conducted in a seepage test tank filled with isotropic sand with a hydraulic conductivity of about 60 m/d indicate that seepage meter efficiency varies widely and decreases unpredictably when the volume of the seepage bag is greater than about 65 to 70 percent full or less than about 15 to 20 percent full. Seepage generally decreases with duration of bag attachment even when operated in the mid-range of bag fullness. Stopping flow through the seepage meter during bag attachment or removal also results in a decrease in meter efficiency. Numerical modeling indicates efficiency is inversely related to hydraulic conductivity in highly permeable sediments. An efficiency close to 1 for a meter installed in sediment with a hydraulic conductivity of 1 m/d decreases to about 60 and then 10 percent when hydraulic conductivity is increased to 10 and 100 m/d, respectively. These large efficiency reductions apply only to high-permeability settings, such as wave- or tidally washed coarse sand or gravel, or fluvial settings with an actively mobile sand or gravel bed, where low resistance to flow through the porous media allows bypass flow around the seepage cylinder to readily occur. In more typical settings, much greater resistance to bypass flow suppresses small changes in meter resistance during inflation or deflation of seepage bags.

A trial of transmitter attachment methods for Shark Bay bandicoots (Perameles bougainville)

In mammal reintroductions, effective post-release monitoring often relies on the use of radio-transmitters. Collars are a popular attachment technique but are not necessarily appropriate for all taxa. However, other attachment methods may result in substantially reduced monitoring durations. We assessed several transmitter types for the Shark Bay bandicoot (Perameles bougainville), aiming to optimise animal welfare and attachment duration. Collars (fitted under general anaesthetic) were considered the optimal method and 12 bandicoots were collared and monitored as part of a reintroduction program. We found that our collars permitted monitoring for up to seven weeks, while causing minimal harm to the animals.

The Influence of Material and Roughness on the Settlement and the Adhesive Strength of the Barnacle Balanus Improvisus in the Baltic Sea

Under natural conditions, barnacles, one of the most prominent marine hardfouling organisms, encounter a vast variety of heterogeneous surfaces including artificial ones, such as ship hulls on which they adhere efficiently. Despite intensive research in the last decades, it is still not clear, how material related factors influence the fouling development under natural conditions, and whether roughness at a microscale affects the release dynamics of barnacles. In order to shed light on the relationship between these substrate factors and their effect on biofouling, both settlement and fouling development of Balanus (=Amphibalanus) improvisus was evaluated on epoxy resin and polyvinylsiloxane (PVS) substrates differing in their roughness (flat, asperity sizes: 0.3µm, 1µm, 3µm, 9µm, 12µm) in a static field trial in the Baltic Sea for 17 weeks performed in 2014. All barnacles on these tested surfaces were individually tracked on a weekly basis, in order to calculate the release to settlement ratios (r/s), to evaluate the fouling- release performance and to monitor the actual attachment duration. It was demonstrated that both stiffness and surface free energy had no strong effect on initial settlement. The total fouling accumulation was nearly identical for epoxy resin and PVS, if fallen-off barnacles were included in the analysis. Roughness influenced initial settlement and fouling development. On PVS the r/s nged between 0.5-0.7 and the attachment duration was around four weeks. However, samples with a roughness of 9µm displayed a lower r/s ratio (0.35) and barnacles showed longer attachment durations (8 weeks). In a second field trial performed in 2017, attachment forces of barnacles were measured after the samples had been immersed for 10 weeks in the Baltic Sea. The shear stresses obtained were similar for substrates with different roughness with around 0.12 MPa and were independent of the barnacle’s size. These findings show that roughness even at the micro scale can impact the fouling release ability of a surface.

A systematic investigation into the effect of fibrillar microstructures on the settlement and attachment strength of the bay barnacle Balanus improvisus under natural conditions

Barnacles are one of the most prominent hardfouling organisms in the marine environment. They are able to adhere efficiently to nearly every surface underwater including artificial ones like ship hulls and maritime installations. This overgrowing can lead to huge economical costs. Previous studies have shown that specific microstructure types including micropillars can reduce the initial settlement of barnacles. However, it is not clear how adult barnacles are influenced by microstructured surfaces and whether microstructures can even decrease the resulting adhesion strength of them under natural conditions. Therefore, the aim of this study was to systematically investigate the influence of height, diameter, aspect ratio and flexibility of fibrillar microstructures made from polydimethylsiloxane (PDMS) on initial settlement of barnacles as well as the permanent attachment of adult ones. Micropillars with three different heights (50 µm, 100 µm, 200 µm) and two different diameters (25 µm, 50 µm) were exposed to the Baltic Sea for 12 weeks. On a weekly basis, all barnacles (Balanus [= Amphibalanus] improvisus) were tracked individually to calculate the release-to-settlement ratio and to capture the average attachment duration prior to detachment. The results have shown that with increasing height, both initial settlement and fouling density development were reduced. An increase of diameter showed a similar relationship but at a much smaller scale. All tested microstructures decreased the detachment rates of barnacles from the surface compared to a flat PDMS control. However, they appear to complicate the development of a strong adhesive joint in the young adult phase. Some grade of flexibility in the microstructures appeared to increase the fouling retention. The results shed light in the interaction between adult barnacle adhesion and microstructures and may help in the development of new antifouling technologies.