Microscope Stage Research Articles

The sintering analysis of biomass waste ash based on the in-situ exploration and thermal chemical calculation in the gasification process

The plentiful biomass wastes are promising fossil energy alternatives to generate indispensable energy. Biomass gasification is an effective way of producing high-value-added productions and reducing CO2 emissions. However, some ash-related issues, especially ash sintering, restrict the wide utilization of biomass energies. To minimize the negative effect of the sintering problem, this work studied the ash sintering process of typical cornstalk waste ash by in-situ experimental methods, including high-temperature stage microscope (HTSM) and thermomechanical analysis (TMA). Then the thermochemical calculation was combined to clarify the sintering mechanism. The result indicated that sintering was the first step during the ash fusion process. The initial sintering temperature (624 °C) was lower than the ash deformation temperature (919 °C), which was the first characteristic temperature of ash fusion tests. The chemical reaction of the inherent ash-related components was the main reason for the appearance of the initial sintering temperature. From the element perspective, the chemical reaction of alkali and alkali earth metals (AAEMs) was mainly involved. The alkali metals tended to react with SiO2 while alkali earth metals were prone to combine with P2O5. Except for ash sintering behavior during the heating process, the TMA trace showed another two stages, swelling and melting. Massive bubbles would be generated from the inside melts at the swelling stage and cause the drastic fluctuation of the ash-melting system until the end of the melting range. Moreover, the high heating rate was beneficial for alleviating the initial sintering temperature while having a tiny influence on changing the total range of sintering and swelling zones.

Pyrolysis and CO2 gasification of biomass in high-temperature stage microscope: Morphological evolution and thermal behaviors

The morphological evolution of biomass particles during pyrolysis and char gasification was investigated by a high-temperature stage microscope (HTSM), and realistic particle shrinkage characteristics were obtained in combination with weight loss properties. Also, product properties were obtained on a fixed-bed and the influence of the physicochemical properties of the char on the gasification activity was considered. Several typical biomass samples were selected, including poplar sawdust, rice husk, and steamed rice. As a starchy biomass, steamed rice particles underwent intense swelling at 300–330 °C, followed by shrinkage, and finally formed an internal loose and porous char, which was significantly different from lignocellulosic biomass. For lignocellulosic biomass, poplar sawdust and rice husk particles showed similar shrinkage processes during pyrolysis. By comparing the curves of particle shrinkage and weight loss, the development of internal pore volume of particles was reflected in a general way, which can better guide the construction of biomass shrinkage mechanism model. The gasification activity of the three biomass pyrolysis chars differed considerably and consistent conclusions were obtained in terms of particle shrinkage, weight loss, and gas products. The poplar sawdust char showed acute shrinkage of particles and loss of weight, exhibiting the strongest gasification activity, 6 times that of rice husk char and steamed rice char. The gasification activity of the char depended mainly on the degree of graphitization and was almost independent of the mesoporous structure. In the temperature range of 800–900 °C, higher gasification temperatures corresponded to more rapid particle shrinkage and weight loss, higher gas product yield, and greater gasification activity.

Giant kelp genetic monitoring before and after disturbance reveals stable genetic diversity in Southern California

Given the impacts of climate change and other anthropogenic stressors on marine systems, there is a need to accurately predict how species respond to changing environments and disturbance regimes. The use of genetic tools to monitor temporal trends in populations gives ecologists the ability to estimate changes in genetic diversity and effective population size that may be undetectable by traditional census methods. Although multiple studies have used temporal genetic analysis, they usually involve commercially important species, and rarely sample before and after disturbance. In this study, we run a temporal analysis of giant kelp, Macrocystis pyrifera, genetic diversity over the scope of 10 years (2008-2018) using the same microsatellite marker panel to assess the genetic consequences of disturbance in several populations of giant kelp (Macrocystis pyrifera) in the Southern California Bight. The study is a rare pre- and post-disturbance microsatellite analysis that included declines to giant kelp caused by the 2015/16 El Nino Southern Oscillation event. We used canopy biomass estimated by remote sensing (Landsat) to quantify the extent of disturbance to kelp beds, and sea surface temperature data to understand how kelp was pushed towards its temperature limits during this period. Despite prolonged periods with decreased canopy at several sites, no changes in genetic structure and allelic richness were observed. We argue that giant kelp in the region is best described as a “patchy population” system where true extinctions are rare. We discuss how deep refugia of subsurface sporophytes and cryptic microscopic life stages could have kept genetic diversity through disturbance. Given the increasing effects of climate change and uncertainty in modeling impacts of species with cryptic life history stages, we suggest further investigation to reveal the role such stages play in species resilience. Genetic monitoring studies of sites selected by remote census demographic and climate surveys should be continued in the future given the predicted impacts of climate change.

Identification of the ejecta deposit formed by the Australasian Tektite Event at Huai Om, northeastern Thailand

AbstractThe Australasian Tektite Event, approximately 0.8 Ma, is the youngest record of a large impact event on Earth. Although it is estimated that it occurred somewhere in Indochina based on the distribution of tektites, the crater has never been located. Here, we report the discovery and occurrence of shocked quartz with planar deformation features (PDFs) in the Quaternary depositional sequence at Huai Om in northeastern Thailand. Measurements of the orientation of lamellae using a universal stage microscope as well as observation using scanning electron microscopy and transmission electron microscopy were conducted to confirm the presence of PDFs. Together with the occurrence of in situ layered tektite fragments, we identify the depositional sequence as the ejecta deposit formed by the Australasian Tektite Event. We further describe the detailed lithostratigraphy of the ejecta deposit, which will allow the tracing of its distribution and lateral changes in its thickness, grain size, and grain composition. Further investigation of the lateral distribution of the ejecta deposit would provide information about the location, magnitude, and target rocks of the Australasian Tektite Event.

A Liquid Metal Encapsulation for Analyzing Porous Nanomaterials by Atom Probe Tomography

Abstract Analyzing porous (nano)materials via atom probe tomography has been notoriously difficult. Voids and pores act as concentrators of the electrostatic pressure, which results in premature specimen failure, and the electrostatic field distribution near voids leads to aberrations that are difficult to predict. In this study, we propose a new encapsulating method for porous samples using a low melting point Bi–In–Sn alloy, known as Field's metal. As a model material, we used porous iron made by direct-hydrogen reduction of single-crystalline wüstite. The complete encapsulation was performed using in situ heating on the stage of a scanning electron microscope. No visible corrosion nor dissolution of the sample occurred. Subsequently, specimens were shaped by focused ion-beam milling under cryogenic conditions at −190°C. The proposed approach is versatile and can be applied to provide good quality atom probe datasets from micro/nanoporous materials.

The Peel-Blot Technique: A Cryo-EM Sample Preparation Method to Separate Single Layers from Multi-Layered or Concentrated Biological Samples.

The peel-blot cryo-EM grid preparation technique is a significantly modified back-injection method with the objective of achieving a reduction in layers of multi-layered samples. This removal of layers prior to plunge freezing can aid in reducing sample thickness to a level suitable for cryo-EM data collection, improving sample flatness, and facilitating image processing. The peel-blot technique allows for the separation of multilamellar membranes into single layers, of layered 2D crystals into individual crystals, and of stacked, sheet-like structures of soluble proteins to likewise be separated into single layers. The high sample thickness of these types of samples frequently poses insurmountable problems for cryo-EM data collection and cryo-EM image processing, especially when the microscope stage must be tilted for data collection. Furthermore, grids of high concentrations of any of these samples can be prepared for efficient data collection since sample concentration prior to grid preparation can be increased and the peel-blot technique adjusted to result in a dense distribution of single-layered specimen.

Pancreatic cancer, radiomics and artificial intelligence.

Patients with pancreatic ductal adenocarcinoma (PDAC) are generally classified into four categories based on contrast-enhanced CT at diagnosis: resectable, borderline resectable, unresectable, and metastatic disease. In the initial grading and staging of PDAC, structured radiological templates are useful but limited, as there is a need to define the aggressiveness and microscopic disease stage of these tumours to ensure adequate treatment allocation. Quantitative imaging analysis allows radiomics and dynamic imaging features to provide information of clinical outcomes, and to construct clinical models based on radiomics signatures or imaging phenotypes. These quantitative features may be used as prognostic and predictive biomarkers in clinical decision-making, enabling personalised management of advanced PDAC. Deep learning and convolutional neural networks also provide high level bioinformatics tools that can help define features associated with a given aspect of PDAC biology and aggressiveness, paving the way to define outcomes based on these features. Thus, the prediction of tumour phenotype, treatment response and patient prognosis may be feasible by using such comprehensive and integrated radiomics models. Despite these promising results, quantitative imaging is not ready for clinical implementation in PDAC. Limitations include the instability of metrics and lack of external validation. Large properly annotated datasets, including relevant semantic features (demographics, blood markers, genomics), image harmonisation, robust radiomics analysis, clinically significant tasks as outputs, comparisons with gold-standards (such as TNM or pretreatment classifications) and fully independent validation cohorts, will be required for the development of trustworthy radiomics and artificial intelligence solutions to predict PDAC aggressiveness in a clinical setting.

Influence of the molecular weight of carboxymethylcellulose on properties of Binder Jetting manufactured parts

The influence of the molecular weight of carboxymethylcellulose as solid binder for additive manufacturing was studied. Three sodium carboxymethyl celluloses with different molecular weights were added to a stoneware. The powders were used on a binder jetting machine using a water-based liquid as a bonding agent. Differential Thermal Analysis and Fusion Tests (Hot Stage Microscope) were carried out to determine the correct firing cycle. The printed parts were characterised before and after firing. The density, roughness, pore size and mechanical strength of the sintered samples were tested.

Raman Spectroscopy of Nascent Soot Oxidation: Structural Analysis During Heating

The effect of oxidation on nascent soot particles is investigated in this work by means of Raman spectroscopy. Three different soot particle samples are produced in a lightly sooting ethylene/air laminar premixed flame and collected at different residence times. The samples are characterized by a different size of primary particles and a different degree of aging and hence graphitization, and they are representative of the early evolution of nascent soot in flames. Oxidation of particles is induced by exposing the samples to a high temperature oxidation treatment in air over a range of temperature 25–500°C. To this aim, a programmable heating microscope stage is used. Thermo-optical transmission (TOT) measurements are used to characterize the chemical composition of pristine particles in terms of organic and elemental carbon content, also providing the pyrolytic carbon fraction of the organic carbon. The TOT results show that the organic fraction is constant for the three conditions. On the other hand, the pyrolytic carbon fraction decreases and the elemental carbon increases when moving from the sample composed of just-nucleated particles to the sample mostly made of mature soot particles. Raman spectroscopy reveals that the thermal oxidation treatment performed on the sample of just-nucleated particles, with the highest organic carbon content, results in a reduction of the amorphous carbon component. Conversely, the sample of mature soot, with the highest elemental carbon content, shows an increase in the amorphous carbon phase after oxidation, which is attributed to fragmentation or the formation of point defects by O2 oxidation. Finally, the thermal oxidation procedure produces a strong reduction in the photoluminescence signal detected from Raman spectra.

Development of a Microscope Stage with Light-Emitting Diodes to Upgrade a Traditional Microscope to a Fluorescence Microscope

Fluorescence microscopy is a useful tool that allows students to learn the principles of fluorescence visually in chemical and biological fields. However, fluorescence equipment has high purchase and maintenance costs and thus may not be available in educational institutions or insufficiently funded laboratories. In this study, a microscope stage with colored light-emitting diodes (LEDs) was designed that enabled the conversion of a traditional inverted microscope into a fluorescence microscope with a view to reducing these costs. A 3D printer was used to produce a microscope stage with 12 holes on the back side, and a standard colored LED was mounted into each hole. To evaluate the performance of the proposed system, Hoechst 33342- and fluorescein diacetate-stained fish-derived PLHC-1 cells were observed using an inverted microscope with this stage. Subsequently, images of the PLHC-1 cells were captured, and they exhibited bright fluorescence. This system can be assembled easily and can be operated by teachers, researchers, and even students. Therefore, it is a useful learning resource for fluorescence detection in educational institutions or laboratories that are not well-funded.

Probing the Intracellular Delivery of Nanoparticles into Hard-to-Transfect Cells.

Hard-to-transfect cells are cells that are known to present special difficulties in intracellular delivery of exogenous entities. However, the special transport behaviors underlying the special delivery problem in these cells have so far not been examined carefully. Here, we combine single-particle motion analysis, cell biology studies, and mathematical modeling to investigate nanoparticle transport in bone marrow-derived mesenchymal stem cells (BMSCs), a technologically important type of hard-to-transfect cells. Tat peptide-conjugated quantum dots (QDs-Tat) were used as the model nanoparticles. Two different yet complementary single-particle methods, namely, pair-correlation function and single-particle tracking, were conducted on the same cell samples and on the same viewing stage of a confocal microscope. Our results reveal significant differences in each individual step of transport of QDs-Tat in BMSCs vs a commonly used model cell line, HeLa cells. Single-particle motion analysis demonstrates that vesicle escape and cytoplasmic diffusion are dramatically more difficult in BMSCs than in HeLa cells. Cell biology studies show that BMSCs use different biological pathways for the cellular uptake, vesicular transport, and exocytosis of QDs-Tat than HeLa cells. A reaction-diffusion-advection model is employed to mathematically integrate the individual steps of cellular transport and can be used to predict and design nanoparticle delivery in BMSCs. This work provides dissective, quantitative, and mechanistic understandings of nanoparticle transport in BMSCs. The investigative methods described in this work can help to guide the tailored design of nanoparticle-based delivery in specific types and subtypes of hard-to-transfect cells.

Interfacial Reinitiation of Free Radicals Enables the Regeneration of Broken Polymeric Hydrogel Actuators

Interfacial Reinitiation of Free Radicals Enables the Regeneration of Broken Polymeric Hydrogel Actuators

MO252: Complement 3 Deposits on Renal Tubule and Glomeruli in Phospholipase A2 Receptor-Related Idiopathic Membranous Nephropathy

Abstract BACKGROUND AND AIMS Evidence shows galactose-deficient IgG4 is able to act complement system via lectin pathway in phospholipase A2 receptor (PLA2R) related idiopathic membranous nephropathy (IMN). However, the severity of PLA2R-related IMN runs parallel with neither the electron microscope stage nor the complement density in situ. We find positive complement factor 3 (C3) deposition on renal proximal tubule in some IMN patients and manage to analysis the relationship between it and the severity of the disease. METHOD We retrospectively involved 113 PLA2R related IMN patients from March 2017 to October 2019. The inclusion criteria were diagnosed by kidney biopsy with complete clinical and pathological data. The exclusion criteria were with any secondary causes such as lupus nephritis type V, Sjogren's syndrome, hepatitis B associated glomerulonephritis and atypical membranous nephropathy. We divided total patients into four subgroups according to the C3 deposition site. We defined no C3 deposition subgroup (40,35%) as C3 appeared in neither glomeruli nor tubule, C3 glomeruli deposition subgroup (32, 28%) as C3 deposited on glomeruli only, C3 tubule deposition subgroup (12, 11%) as C3 deposited on tubule only, C3 extensive deposition subgroup (29, 26%) as C3 deposited on both glomeruli and tubule. RESULTS Clinical data of four groups were as follows: Male/female ratio were 22/18, 23/9, 5/7, 16/13, P = .252; The median of age were 50 (33, 57), 51 (42, 57), 57 (49, 61), 51 (33, 57), P = .412; The median of were 24-h urine protein were 4.4 (2.0, 6.9), 5.0 (2.7, 8.3), 4.9 (2.5, 11.2), 5.5 (2.4, 10.2) g/L, P = .427. The average serum albumin were 28.6 ± 6.8, 27.2 ± 6.7, 24.6 ± 2.7, 25.5 ± 6.0 g/L, P = .046. The median of serum creatinine were 70 (57, 82), 77 (65, 92), 68 (57, 89), 69 (58, 80) μmol/L, P = .255. The median of serum C3 were 1.14 (1.0, 1.33), 1.17 (1.04, 1.36), 1.22 (1.0, 1.34), 1.11 (0.99, 1.23) g/L, P = .291. The median of anti-PLA2R antibody were 0 (0, 55), 29 (25, 33), 12 (0, 136), 35 (19, 131) RU/mL, P = .049. CONCLUSION There were differences in serum anti-PLA2R antibody and Alb in patients with different C3 deposition. Patients with extensive C3 deposition showed higher PLA2R antibody.

Clamping Skeletal Muscle PO2 Eliminates Hyperinsulinemic Microvascular Blood Flow Response

ObjectiveTo determine if insulin mediated hyperemia is partially dependent on local muscle oxygen concentration.HypothesisThe blood flow responses to insulin are partially mediated by the local metabolic demand reflecting the increased oxygen consumption required to uptake and convert glucose into glycogen in skeletal muscle.Methods16 male Sprague Dawley rats (161g ‐ 204g) were anesthetized with sodium pentobarbital, the carotid artery and jugular vein were then cannulated for blood pressure monitoring and fluid resuscitation. Following cannulation, the extensor digitorum longus (EDL) was isolated and reflected onto an inverted microscope. Intravital video microscopy sequences of the EDL microcirculation were recorded during baseline and following hyperinsulinemic euglycemia or sham in all experiments. The muscle was reflected over a glass stage insert during Experiment 1a and 1b which allowed for direct observation of microvascular blood flow response to systemic insulin infusion in Experiment 1a. Experiment 1b consisted of a sham hyperinsulinemic euglycemic clamp which involved infusing saline at similar rates as insulin and glucose in standard clamp procedures. In Experiment 2, the EDL was reflected over a gas exchange chamber and microvascular capillary blood flow was recorded during sequential changes (7%‐12%‐2%‐7%) of oxygen concentration [O2] within the chamber during baseline and euglycemic conditions. The gas exchange chamber is fitted into the stage of an inverted microscope that interfaces directly with the EDL via a gas permeable polydimethylsiloxane membrane. By adjusting the concentration of gases flowing through the gas exchange chamber we have direct control of the [O2] within the overlying muscle. Hemodynamic measurements including capillary red blood cell (RBC) velocity, supply rate (SR), hematocrit, and oxygen saturation (SO2) were taken from in focus capillaries in the EDL during each experiment and analyzed offline using custom MATLAB software. All animal protocols were approved by Memorial University’s Institutional Animal Care Committee.ResultsIn Experiment 1a, the hyperinsulinemic euglycemic clamp caused a significant increase in SR from 8.9 ± 3.1 to 14.2 ± 4.9 cells/s at baseline to euglycemia (p = 0.01; N = 6, 677 capillaries at baseline and 552 at clamp), while no significant SR variation was detected after performing a sham clamp in Experiment 1b (11.0 ± 1.6 cells/sec at baseline and 11.4 ± 3.7 cells/sec at sham clamp; N = 6, 837 capillaries at baseline and 724 at sham clamp). In Experiment 2 using the gas exchange chamber, SR significantly decreased at 12% O2 (p = 0.01, p < 0.03) and significantly increased at 2% O2 (p = 0.01, p < 0.04), compared to baseline 7% O2, under both baseline and euglycemic conditions respectively (N = 6, 313 capillaries at baseline and 195 at clamp). SR responses to oxygen oscillations during euglycemia were not different to those at baseline for each O2 concentration (p > 0.9). SO2 significantly increased at 12% O2 and significantly decreased at 2% O2 under both baseline and euglycemic conditions (p < 0.05).ConclusionsOur saturation measurements demonstrate the effectiveness of using a gas exchange device to manipulate local oxygen concentrations in the muscle. Our SR results suggest the increase in blood flow observed in response to insulin is eliminated if the tissue oxygen microenvironment is fixed at a given [O2].

Development of thin‐film micro‐outlet devices for spatially constraining local O2 perturbations to capillaries

ObjectiveTo develop and validate thin film micro‐outlet devices to study microvascular blood flow responses to localized changes in skeletal muscle oxygen concentration ([O2]).HypothesisOxygen mediated blood flow regulation is initiated at the capillary level through red blood cell (RBC) oxygen saturation (SO2) dependent mechanisms.Methods10 Sprague‐Dawley rats (159‐190g) were anesthetized and instrumented to maintain cardiovascular state. The right extensor digitorum longus (EDL) muscle was blunt dissected, isolated, and reflected onto a gas exchange chamber (GEC) mounted in the stage of an inverted microscope. The GEC and EDL were coupled via a composite gas permeable membrane and a gas impermeable film fabricated with laser machined micro‐outlets of various diameters (200 μm, 400 μm, 600 μm). [O2] in the EDL was dynamically manipulated by imposing four sequential 1‐ minute [O2] oscillations between 7‐12‐2‐7% while recording intravital video for capillary RBC SO2 and hemodynamic measurement.ResultsO2 oscillations imposed on capillaries directly overlying 400 μm micro‐outlets caused significant changes in capillary SO2 at 12% GEC [O2], 86.72 ± 9.58%, and 2% GEC [O2], 46.36 ± 15.45%, compared to baseline 7% GEC [O2] 69.09 ± 13.94% (p<0.0001). SO2 in capillaries outside the outlet and within a 100 μm distance had significant changes at 2% GEC [O2], 59.38 ± 21.49% compared to baseline 7% GEC [O2], 50.88 ± 18.81% (p<0.0401). SO2 in capillaries >100 μm away from the micro‐outlets were not different following the same GEC [O2] oscillations. GEC [O2] oscillations on capillaries overlying 600 μm micro‐outlets caused significant changes in capillary SO2 at 12% GEC [O2], 83.43 ± 10.18, and 2% GEC [O2], 44.52 ± 15.77%, compared to baseline 7% GEC [O2], 66.27 ± 11.83% (p<0.0001). SO2 in capillaries outside 600 μm outlets were not different following GEC [O2] oscillations. GEC [O2] oscillations on capillaries overlying 400 μm micro‐outlets caused significant changes in capillary RBC supply rate (SR) at 2% GEC [O2], 11.96 ± 9.39 cells/s, compared to baseline 7%, 10.08 ± 7.69 cells/s, and were significantly different at 2% compared to 12% GEC [O2], 9.98 ± 7.99 cells/s (p<0.0014). GEC [O2] oscillations with 600 μm micro‐ outlets caused significant changes in SR at 2% GEC [O2], 14.14 ± 10.52 cells/s compared to baseline 7% GEC [O2], 11.10 ± 9.37 cells/s, as well as a significant change at 2% GEC [O2], compared to 12% GEC [O2], 10.16 ± 8.88 cells/s (p<0.0001).ConclusionsOur composite thin‐film micro‐outlet devices were fabricated and validated to spatially confine O2 perturbations to capillaries using micro‐outlets of varying diameters. These results demonstrate that our devices can profoundly manipulate capillary SO2 and alter capillary RBC SR in vessels directly overlying the micro‐outlet without affecting capillary SO2 at distances greater than 100 μm outside the outlets. 400 μm micro‐outlets are capable of provoking significant changes in capillary SR, with larger 600 μm outlets producing a more robust response. Our novel composite thin‐film micro‐outlet devices demonstrate that regions ~400 μm in diameter must be stimulated to elicit capillary flow responses.

Microvascular Blood Flow Response to Hyperinsulinemic‐Euglycemic Clamp in Zucker Diabetic Sprague Dawley Rat Model of Type 2 Diabetes

ObjectiveQuantify and characterize the skeletal muscle microvascular blood flow in Zucker Diabetic Sprague Dawley (ZDSD) rat model of T2D at rest and during a hyperinsulinemic‐euglycemic clamp.HypothesisChronic hyperglycemia in the ZDSD rat model of T2D causes blunted capillary hemodynamic response to hyperinsulinemic‐euglycemic clamp compared to the age and diet matched control Sprague Dawley (SD) rats.MethodsBiweekly blood glucose and conscious blood pressure measurements were collected from 7‐ to 25‐week‐old male SD (n=12) and ZDSD (n=18) rats. At 27 weeks of age, animals were fasted overnight prior to intravital video microscopy experiments. On the day of experiment animals were anaesthetized with an intraperitoneal injection of pentobarbital, tracheotomized, and carotid and external jugular cannulas were inserted to monitor physiological status and for administration of fluids. The extensor digitorum longus (EDL) muscle of the lower hind limb was isolated, blunt dissected and reflected over a glass coverslip on the stage of an inverted microscope. Recordings of the EDL were completed at baseline and during hyperinsulinemic‐euglycemic clamp. Hyperinsulinemic‐euglycemic clamp was achieved by continuous intravenous infusion of insulin (Humulin R 2U/hr/kg) and a 50% glucose mixture to titrate blood glucose to euglycemia (5‐7 mM). Mixed blood samples were collected from a tail clip to determine systemic blood glucose. Analysis of intravital videos were completed offline using custom MATLAB software. ZDSD rats that had fasting blood glucose of less than 20 mM at 19 weeks of age were excluded from the hyperglycemic group. Animals exhibiting aberrant microvascular blood flow at baseline or during euglycemic clamp were excluded from the data set. All animal protocols were approved by Memorial University of Newfoundland’s Animal Care and Use Committee.ResultsHyperglycemic ZDSD rats had a significantly higher blood glucose than SD controls from 17 to 25 weeks old and at the beginning of euglycemic clamp (26.13 ± 0.97 and 5.95 ± 0.37, p < 0.0001, Fig 1A). SD rats had a significantly higher glucose infusion rate than ZDSD rats (22.58 ± 1.81 and 13.19 ± 2.76, p < 0.0001, Fig 1B). SD rats had a significant increase in red blood cell (RBC) velocity (149.8 ± 56.71 and 210.0 ± 62.14 µm/s, p = 0.0051, Fig 2A), RBC supply rate (SR) (12.49 ± 8.23 and 19.91 ± 12.25 cells/s, p = 0.004, Fig 2B) and RBC oxygen saturation(sO2) (38.05 ± 11.65 and 45.70 ± 10.13, p = 0.014, Fig 2D) between baseline and euglycemia. However, ZDSD animals had no significant difference in RBC velocity (178.1 ± 63.91 and 194.7 ± 37.69 µm/s, p = 0.3683, Fig 2A), RBC supply rate (14.63 ± 7.55 and 20.03 ± 7.46 cells/s, p = 0.0704, Fig 2B), hematocrit (31.03 ± 3.23 and 33.02 ± 6.22 %, p = 0.4309, Fig 2C), and RBC sO2 (61.91 ± 11.40 and 64.00 ± 11.59, p = 0.5324 Fig 2D). The RBC sO2 was significantly higher in ZDSD than SD at baseline (61.91 ± 11.40 compared to 38.05 ± 11.65, p = 0.0166, Fig 2D).ConclusionSD rats had a robust increase in capillary hemodynamics during hyperinsulinemic‐euglycemic clamp. However, the skeletal muscle capillary hemodynamics of ZDSD rats did not significantly change between baseline and during euglycemia. These finding suggests a potential impairment in skeletal muscle microvascular blood flow response in this type 2 diabetic rodent mode. The elevated RBC sO2 in ZDSD rats may indicate a dysregulation of capillary blood flow in the ZDSD model.

In-situ study of fractal properties of coal char particles during catalytic gasification

Interactions of potassium-based catalysts with Shenfu (SF) char during catalytic gasification was observed by an in-situ heating stage microscope. The effects of the gasification temperature (800–900 °C) and the catalyst loading (4.4%, 10%) on the reactivity of coal char were investigated. The heating stage microscopy was used to visualize the catalytic gasification process of coal char particles and the fractal theory was introduced to analyze the surface structure of coal char particles to reveal the gasification reactivity. The experimental results show that the fractal dimension of coal char particles is positively correlated with the carbon conversion rate, and the fractal dimension increases by increasing the gasification temperature and the catalyst loading. The relationship between the initial gasification reaction rate and the fractal dimension of coal char particles is consistent with that between the carbon conversion rate and the fractal dimension of coal char particles. There is an exponential relation between the fractal dimension of coal char and the char angle; the fractal dimension increases with the increase of coal char particle angle; and the fractal dimension of coal char particles can be used in the study of coal char catalytic gasification process.

It’s the Little Things: The Role of Microscopic Life Stages in Maintaining Kelp Populations

Kelp forests are experiencing broad scale declines in abundance and shifts in latitudinal ranges in many areas of the world due to numerous environmental stressors, especially those associated with climate change. While the majority of studies on kelp ecology have focused exclusively on the macroscopic sporophyte life stage, a growing number of studies is showing quite convincingly that the microscopic zoospore and gametophyte life stages can be important to establishing spatial patterns in these marine forests, and in facilitating their recovery following deforestation. Unfortunately, their microscopic sizes have made them difficult to study in the field, leading to a ‘black box’ surrounding what we know about their ecologies. However, advances in experimental methodologies and a growing number of laboratories studying kelp microscopic life stages are revealing how they are affected by variability in environmental conditions, and are providing a clearer picture of how kelp forests might respond to a changing ocean climate. These studies have largely revealed that kelps can disperse over a wide range of distances, enhanced by the synchronous release and vertical transport of zoospores into shallower water, and by floating rafts of reproductive thalli. Settlement on the benthos is facilitated by both positive and negative chemotaxis, and by active selection of microhabitats that favor their growth and survival. Following settlement and subsequent germination, the haploid gametophytes can delay their development and form a bank of microscopic forms that persist during periods that are unfavorable for the large sporophyte populations, or they can develop and undergo sexual reproduction during which they respond to variability in environmental conditions. In particular, they are strongly affected by increases in irradiance (PAR, UVA + UVB) and temperature, decreases in nutrients and salinity, and by sedimentation and grazing. However, the manner in which they respond to these stressors varies among species and with their geographic distributions, which is integral to establishing biogeographic patterns in the large sporophyte populations. Given these factors are expected to change as the ocean climate changes, these species-specific responses have significant implications for future patterns of distribution and abundance of these iconic marine forests.

Grazing and Recovery of Kelp Gametophytes Under Ocean Warming

Kelp forests are economically important ecosystems that support a wealth of biodiversity but are declining globally. They are often replaced by biologically depauperate alternate stable states dominated by turfing algae. Hysteresis maintains algal turfs by inhibiting kelp recruitment, preventing the reestablishment of kelp forests. The mechanisms inhibiting kelp recruitment remain poorly understood as microscopic stages of kelp are difficult to study in situ. A potential mechanism contributing to the suppression of recruitment may be turf-facilitated grazing of kelp gametophytes, the haploid free-living reproductive life stage. Here we assess the resilience of kelp gametophytes to grazing pressure from a gastropod micrograzer commonly present in turf under current and future ocean warming scenarios. Gametophyte coverage and abundance were significantly reduced following grazing under all temperatures, however there was no significant effect of temperature on grazing rates. Once grazing pressure was removed, gametophyte abundance recovered to control levels, but the total coverage and length of gametophytes continued to decline in all treatments. Gametophytes were found to survive micrograzer ingestion and continued to grow in aggregations in the gastropod’s mucus trail and faeces, even producing sporophytes. Gametophyte survival post-ingestion may positively contribute to dispersal and sporophyte recruitment, however the lack of gametophyte recovery at elevated temperatures may counteract this effect under future ocean warming. Taken together, this study demonstrates complex interactions that take place in the turf micro-habitat of kelp gametophytes and highlights biotic factors influencing transitions between kelp forests and algal turfs.

Design of a scanning acoustic and photoacoustic microscopy system using open-source hardware and software components

We have designed and started construction of an instrument that will be able to operate as both a scanning acoustic microscope and photoacoustic microscope. To keep costs down, we are using open-source hardware and software components wherever possible. The system is designed to scan specimens that are approximately 2 cm × 2 cm in lateral dimensions with lateral steps of 1 micron or less. When operating as a scanning acoustic microscope, the specimen will be water-coupled to a high-frequency ultrasound transducer operating in pulse-echo mode. When operating as a photoacoustic microscope, short light pulses infrared laser diode located under the specimen will generate ultrasound pulses thermoelastically, which will then be received by a confocal high-frequency transducer. In both cases, the specimen will be raster-scanned under the transducer by a moving stage. The mechanical scanning system was designed and built using a spring-loaded microscope stage, micrometers, stepper motors, a shield board used for 3D printers, an Arduino Mega microcontroller, and a Raspberry Pi 4 microcomputer. A graphical user interface has been written in Python using Tkinter to send the motion control commands to the stage. Future work will include incorporation of the laser and transducer control systems.