Minute Pores Research Articles

Mechanical properties and ductility improvement mechanisms of fiber-reinforced biomimetic mineralized composites using sea sand

Biomimetic mineralized composites (BMC) is an emerging green cementing material. However, the application of BMC is limited by brittle failure. This study proposes novel fiber-reinforced biomimetic mineralized composites (FRBMC) with excellent ductility based on the coupling method of fiber reinforcement and biomimetic chemically induced calcium carbonate precipitation (BCICP). Three typical fibers, including polymer fibers (polypropylene fiber, PF), mineral fibers (basalt fiber, BF), and plant fibers (coir fiber, CF), were used to explore the feasibility of application in FRBMC. Accordingly, mechanical properties, pore structures, and microscopic characteristics were assessed through unconfined compressive strength (UCS) test, mercury intrusion porosimetry (MIP) tests, and scanning electron microscopy (SEM). The results show that fiber induces a transition from brittle to ductile failure modes in BMC. PF exhibits the most notable enhancement in residual strength and peak strain, while BF leads to the highest compressive strength. CF can effectively enhance energy absorption after reaching peak stress. Moreover, FRBMC with CF contains a higher quantity of minute pores, while BF can reduce the porosity of FRBMC. The calcium carbonate crystals effectively cement fibers and sand particles, enhancing the ductility of FRBMC through forming various cementing structures. This study investigates the synergistic effect of BCICP and fiber reinforcement, providing valuable guidance for potential practical applications of FRBMC.

Application of Differential Equation in the Design of Dialysis Machine

In this work, I have discussed the application of differential equations in the design of a dialyzer machine. A dialyzer is a device through which blood flows from the patient's body into the machine. A substance called dialysate flows through the machine in the opposite direction to the blood. This aids in separating waste materials with the help of a semipermeable membrane attached to the machine. This membrane possesses minute pores that allow the passage of waste matter, which has much smaller molecules than the blood cells, but restrict the passage of blood itself. The design of the dialyzer machine concerns the flow rate of the waste material through the membrane. This flow-rate is determined by the differences in concentration of waste material on either side of the membrane, where, the flow occurs from high concentration to low concentration.

Composite hydrogels fabricated from konjac glucomannan and gellan gum: Rheological characterization and their potential application in sustainable agriculture

In this study, konjac glucomannan (KG) was incorporated in high acyl gellan (HAG) and low acyl gellan (LAG) hydrogels in different ratios. The addition of KG increased pseudoplasticity and thermal hysteresis values of the hydrogels. Improvement in elasticity and water holding capacity (WHC) was observed in KG-LAG hydrogels. The highest WHC (98.5 %) was observed for 1K1H (KG:HAG = 1:1) and 3K7L (KG:LAG = 3:7) hydrogels. The crystallinity of the composite hydrogels was lower than hydrogels prepared from individual biopolymers. The hydrogels exhibited a rough surface with minute pores in the cross-section, due to the aggregation of glucomannan on the gellan network in the composite hydrogels. While HAG and 1K1H hydrogels exhibited greater swelling at low pH (3.0), LAG and 3K7L exhibited greater swelling at high pH (11.0). At pH 7.0, the hydrogels exhibited swelling indices >300 %. Incorporation of 1K1H hydrogel at 10 % (w/w) in sandy loamy soil under semi-arid conditions increased the germination of fenugreek microgreens from 60 % to 80 % on the 15th day. Furthermore, the moisture evaporation rate of the soil reduced from 35 % to <15 %, positively impacting the physicochemical properties of the microgreens. The composite hydrogels were successful in achieving a controlled release of phosphate fertilizer.

MoS2 modified g-C3N4 composite: A potential candidate for photocatalytic applications

A potential photocatalytic activity of MoS2-modified g-C3N4 composite for methylene blue (MB) dye degradation is processed under sunlight radiation. The photocatalyst materials (g-C3N4, MoS2, and g-C3N4/MoS2) were prepared by low-temperature hydrothermal method and the synthesized samples were further characterized through the X-ray diffraction (XRD), UV–vis diffuse reflectance spectrometer (DRS), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and Photoluminescence (PL) spectroscopy techniques. Initially, the formation of the crystalline structure of (g-C3N4, MoS2, and g-C3N4/MoS2) samples was identified through the XRD technique. Further, the morphology of the MoS2-modified g-C3N4 when observed through SEM was found to be a regular structure with minute pores and voids when compared to the other two samples resulting in better light absorption capacity. The elemental composition of synthesized composite is analyzed by XPS spectra. The energy band gap investigated through the DRS spectra was 2.9 eV, 1.8 eV and 1.82 eV for the g-C3N4, MoS2, and g-C3N4/MoS2 samples respectively. Further BET, TOC and scavenger radical analysis was conducted on the tested sample to analyze the degradation process. Thus, the composite photocatalyst material of MoS2-modified g-C3N4 has an enhanced recombination electron-hole pair rate. Finally, the photocatalytic feature of the composite (g-C3N4/MoS2) tested on MB dye solution under sunlight irradiation for 2 hr was found to be successful.

Durability performance of self-compacting concrete produced using CO2 as an admixture

This research investigates the fresh characteristics and durability of self-compacting concrete (SCC) made using CO2 as an admixture. In the existing practice, CO2 is added to concrete mainly through accelerated carbonation curing. That has many limitations, such as low diffusion rate, requirements of the large airtight chamber, and use in precast concrete only. To overcome these limitations, the current study employed a CO2 mineralization approach. As cementitious materials hydrate during mixing, CO2 reacts with it and produces more hydration products. In addition, calcium carbonate particles are formed in situ, filling the minute pores and densifying the SCC matrix. The present research results reveal that a small quantity of CO2 mineralization improves the SCC compressive strength and durability; the best durability is achieved at 0.3% mineralization of CO2 by the weight of the cement used. Compare to normal SCC, a 4.3% higher compressive strength of CO2 mineralized SCC was noticed at 28 days of testing. 0.05 % lowers weight gain and 1.88 % higher compressive strength was noticed in CO2 mineralized SCC at 180 days of 5% sodium sulfate exposure condition. Similarly, the rapid chloride penetration test result shows that 11.35% lesser chloride ions pass from CO2 mineralized SCC compared to normal SCC. The fresh characteristics of the SCC as a result of CO2 mineralization behave similarly to reference SCC with small degradation that is considered acceptable. Hence, thepresent study demonstrates that CO2 can be used beneficially in concrete to enhance its properties and lower CO2 emissions into the atmosphere.

Treating Bilateral Cornual Tubal Block by Ayurvedic Medications: A Case Study

Tubal diseases accounts for 25%–35% of infertility in women. The line of treatment for it is tubal cannulation and microsurgical reconstruction. Moreover, In Vitro Fertilization (IVF) is suggested to patients post tubal microsurgery. These treatments have low success rate but have high costs. Hence, it is important to look for alternative therapies which are safe and cost-effective. From an Ayurvedic perspective, tubal blockage can be considered as Sangha Srotodushti of Artavabeejvaha srotas due to vitiated Tridosha. This is a case report of a female patient with a Bilateral cornual tubal block with a history of infertility. Due to Kapha -Vata dosha, 5ml Kshartail Uttarbasti was planned for 2 days for 3 consecutive menstrual cycles to remove obstruction produced in the tube. Due to Vyavayi (spreading fast throughout the body), Vikasi (distribution throughout the body without routine digestive process), and Sukshma (minute) properties of Kshartail, it spreads quickly into minute pores of the tube. Due to its Ushna (hot), Tikshna (penetrates deep tissue), Chedan (punctures tissue), and Bhedan (break down of particles) properties it scrapes the obstructing substance and removes fibrosed and damaged endometrial lining of the tube &amp; uterus. Due to its Avakashkara (produces space), Srotoshodhak (purification of srotas) Ropan (wound healing), and disinfectant properties, it promotes the rejuvenation of tissue and improves the conductive functions of tubes and its Snigdha (oily), Ushna (hot) properties neutralises vitiated Vata dosha. After removal of the tubal block, the patient gets conceived naturally within 4 months and delivers a healthy baby. The result suggests that Uttarbasti is a highly effective, safe, low-cost Ayurvedic treatment without apparent complications.

Performance of sunflower petal shaped CuCo2S4 wrapping on GO asymmetric capacitor for energy storage applications

Bimetallic sulfides possess great interest in energy storage application because of its multiple merits. In the present work, petal shaper CuCo2S4@GO was prepared by simple hydrothermal method and serves an active electrode to analyze for supercapacitor applications. FESEM images shows that wrapping of GO on the surface of CuCo2S4 shows petal shaped needle like structure with minute pores in it. It is noted that GO wrapped CuCo2S4 delivers the excellent electrochemical performance with the specific capacitance of about 900 Fg−1 with the capacity retention of about 80% after 5000 cycles. Addition to this asymmetric capacitor was fabricated by using CuCo2S4@ GO (3%) and AC as positive and negative electrode and delivers the higher energy and power density (47.2 Wh·kg−1, 0.896 kW·kg−1) and long cycling stability after 10,000 cycles. The electrochemical performance shows that CuCo2S4@GO will be a great electrode for energy storage applications.

Rhodomonas storeatuloformis sp. nov. (Cryptophyceae, Pyrenomonadaceae), a new cryptomonad from the Black Sea: morphology versus molecular phylogeny

We established a new cryptomonad species, Rhodomonas storeatuloformis sp. nov., based on morphological and molecular characters of cultured strain isolated from the Black Sea. Cells are slightly dorsoventrally flattened, obloid in shape, 12-19 &#181;m in length and 5-10 &#181;m in width, with light-brown, parietal H-shaped chloroplast and a central pyrenoid. Two unequal flagella are located subapically in a short V-shaped vestibulum with a ligule on the left side. Cells are covered by a sheet-like papillate perisplast with numerous small underlain ejectosomes; discharged ejectosomes form distinctly visible minute pores. Mid-ventral band is absent. In general, cell morphology is very similar to described strains of Storeatula genus. However, phylogenetic analyses based on sequences of the partial nuclear 18S, 28S rDNA, and complete internal transcribed spacer (ITS) region of rDNA placed the novel cryptomonad strain within Rhodomonas genus as a separate clade. The predicted secondary structure of nuclear rDNA ITS2 has numerous compensatory base changes compared to the closest relative strains that support the distinction of the novel species among Rhodomonas taxa. The present results contribute to the study on still hidden cryptomonad biodiversity in the Black Sea. Contradiction between morphology and phylogenetic data in R. storeatuloformis further argues for revision of the generic delineations in the family Pyrenomonadaceae.

An experimental studies on strength properties of bacterial concrete

Cement concrete is a massively “used construction material throughout the world and in the process of manufacturing of one ton of cement 850 kg of CO2 is emitted into the atmosphere, In this research, bacterial concrete was produced by replacing part of cement in controlled concrete with equal volume of class F fly ash enriched with bacteria Bacillus sphaericus (B. sphaericus) such that the strength of 28 days of bacterial concrete is at par with controlled concrete. B. sphaericus precipitate Calcium Carbonate while producing bacterial culture which fills the minute pores in bacterial concrete and makes it to attain higher strength. Experiments were made by replacing cement from 0% to 50% with class F fly ash enriched with bacteria B. sphaericus and found that”bacterial concrete made with of 25% replacement (M2CFB25) is suitable in fresh state and in hardened state. In fresh concrete with water cement ratio of 0.4 the compaction factor of controlled concrete (M2CC) was 0.85, fly ash concrete with 25% replacement to cement (M2CF25) was 0.84 whereas for M2CFB25 it was 0.89 which is more advantageous for M2CFB25to get good compaction. Compressive strength of 28 days concrete M2CC, M2CF25 and M2CFB25 are 45.19 N/mm2, 41.23 N/mm2 and 48.11 N/mm2. Similarly 28 days concrete split tensile and flexural strength of M2CFB25 is higher than M2CC and M2CF25. Fly ash concrete M2CF25 has gained less compressive strength, split tensile and flexural strength than M2CC on 28 days of curing. X-Ray diffraction test results indicated M2CFB25 have more peaks than M2CC and M2CF25 and there by confirmed the presence of higher CaCO3 in bacterial concrete. The usage of bacterial concrete M2CFB25 in lieu of M2CC will reduce the amount of CO2 emitted to the atmosphere and reduce the depletion of natural resources.

Utilization of nanoporous biosilica of diatoms as a potential source material for fabrication of nanoelectronic device and their characterization

Biosilica obtained from frustules of diatoms have very delicate nanostructures similar to many micro- and nanofluidic devices. In the present investigation, a cheaper and ecofriendly metal-oxide-semiconductor (MOS) tool has been fabricated exploiting frustules of the diatom Halamphora subturgida. The structural, optical, and chemical characterizations of the cleaned frustules of cultured diatom were investigated through various techniques. Electron microscopic images revealed intricate morphology of the nanostructured silica with very minute pores making the frustules very hard but light material. UV-Vis spectroscopy showed maximum absorbance at 223 nm. The absorption maximum for photoluminescence was centered at 462 nm and that of cathodoluminescence was at 439.9 nm and 466.6 nm. Bulk of extracted silicon dioxide (SiO2) nano-powder from diatom frustules was used as a source material for preparing a high-quality crystalline film on P-type silicon (p-Si) by vapor-liquid-solid (VLS) method. The crystalline quality of the film was tested by X-ray diffraction (XRD) and the crystalline size obtained was 62 ± 2.4 nm. From scanning electron microscopic (SEM) investigation, the growth of a continuous film from diatom biosilica on p-Si substrate was revealed. The thickness of the as-grown SiO2 film was 22.2 ± 1.6 nm, obtained from spectroscopic ellipsometry (SE) study. The performances of fabricated Al/SiO2/Si metal-oxide-semiconductor capacitor were tested by measuring leakage current (~ 43 ± 8 × 10−11 A μm−2 at +2 V), capacitance-voltage, constant current (0.1 μA), and voltage stress (at − 2 V) for reliable gate dielectrics applications in MOS devices. Overall, the process was cost-effective and provides an alternative technique to design high-quality diatom-derived “Bio-SiO2 films” on p-Si substrate.

Pores for Thought: Can Genetic Manipulation of Stomatal Density Protect Future Rice Yields?

Rice (Oryza sativa L.) contributes to the diets of around 3.5 billion people every day and is consumed more than any other plant. Alarmingly, climate predictions suggest that the frequency of severe drought and high-temperature events will increase, and this is set to threaten the global rice supply. In this review, we consider whether water or heat stresses in crops — especially rice — could be mitigated through alterations to stomata; minute pores on the plant epidermis that permit carbon acquisition and regulate water loss. In the short-term, water loss is controlled via alterations to the degree of stomatal “openness”, or, in the longer-term, by altering the number (or density) of stomata that form. A range of molecular components contribute to the regulation of stomatal density, including transcription factors, plasma membrane-associated proteins and intercellular and extracellular signaling molecules. Much of our existing knowledge relating to stomatal development comes from research conducted on the model plant, Arabidopsis thaliana. However, due to the importance of cereal crops to global food supply, studies on grass stomata have expanded in recent years, with molecular-level discoveries underscoring several divergent developmental and morphological features. Cultivation of rice is particularly water-intensive, and there is interest in developing varieties that require less water yet still maintain grain yields. This could be achieved by manipulating stomatal development; a crop with fewer stomata might be more conservative in its water use and therefore more capable of surviving periods of water stress. However, decreasing stomatal density might restrict the rate of CO2 uptake and reduce the extent of evaporative cooling, potentially leading to detrimental effects on yields. Thus, the extent to which crop yields in the future climate will be affected by increasing or decreasing stomatal density should be determined. Here, our current understanding of the regulation of stomatal development is summarised, focusing particularly on the genetic mechanisms that have recently been described for rice and other grasses. Application of this knowledge toward the creation of “climate-ready” rice is discussed, with attention drawn to the lesser-studied molecular elements whose contributions to the complexity of grass stomatal development must be understood to advance efforts.

Ultrastructure of the genital papillae in the fresh-water mite Limnochares aquatica (L., 1758) (Acariformes, Limnocharidae)

The genital papillae of the fresh-water mite, Limnochares aquatica (L., 1758) were studied using TEM and SEM methods. The papillae are multiple organs spreading in large number over the ventral body surface. Each papilla is composed of the basal internal portion immersed into the body cavity and the external bowl-shaped portion placed among cuticular protuberances. A semi-spherical cap bearing minute pores covers the papillae bowl. An electron-lucent chamber is present between the cell apexes and the cuticle of the papillae cap. The latter is formed of the endo- and the exocuticle pierced by pores. The papillae are built of columnar cells with nuclear zone occupying the basal portion and the apical zone extending within the bowl and forming plications of the apical plasma membrane. Numerous electron-clear vesicles detach from both the basal and the lateral plasma membrane of papillae cells. The mitochondrial pool is quite moderate. The cells also contain numerous axial microtubules, glycogen particles, single residual bodies as well as minute apical vesicles supposedly releasing secretion into the lucent chamber. This secretion is accumulated underneath the cuticle of the cap and moving out through the pores to the outside. Following TEM organization, the papillae function in vesicular transportation of exceeding water and solutions across the organ from the organism to the external medium. The reverse active path of ions through the apical plasma membrane is also possible. In general, the papillae organization corresponds to chloride cells of aquatic insects taking part in ion–water balance but seems to be more primitive than analogous organs of other mites studied.

Description of two novel Echinochasmus species (Digenea: Echinostomatidae) from the squacco heron Ardeola ralloides (Aves: Ardeidae) in Egypt: A light and scanning electron microscopic study

Adult forms of two new echinostomatids were recovered from small intestine of six out of ten squacco herons, Ardeola ralloides collected from March to July 2019 from Giza governorate, Egypt. These small-sized parasites had a single row of collar spines with middle dorsal interruption, vitellaria reaching the level of ventral sucker and attributed to genus Echinochasmus, namely, E. ralloides n. sp. (prevalence 40%) and E. rawashi n. sp. (prevalence 20%). The morphometric features and differential indices of two species were measured, compared and described using light and scanning electron microscopy (SEM). The body of E. ralloides n. sp. measured 959.2-1090.6 × 264.3-311.1 μm (L × MW). It was provided with 26 collar spines (9 dorsal, 2 lateral and 2 angle on each side of the dorsal collar interruption), lacked of tegumental spines except for small areas in lower left and lateral right margins of ventral sucker, and characterized by presence of many minute pores of 3.1-3.8 μm on dorsal surface of hindbody. The body of E. rawashi n. sp. measured 638.8-1173.5 × 138.8-207.7 μm (L × MW), provided with 24 collar spines (7 dorsal, 2 lateral and 2 angle on each side of the dorsal collar interruption) and had scale-like tegumental spines distributed on whole ventral surface and anterior 1/4 of dorsal surface of body, ended by up to 13 digit-like structures and measured 2.1-2.5 × 4.4-4.8 μm.

Functional morphology of the venom apparatus of Prorhynchus stagnalis (Platyhelminthes, Lecithoepitheliata)

The microturbellarian Prorhynchus stagnalis quells prey with a venom apparatus that also serves as its copulatory organ when the animal is mature. While it has long been known to comprise a tubular, sharp-pointed stylet surrounded concentrically by two mantles of longitudinally aligned rods, our examination of it by electron microscopy and confocal microscopy reveal unexpected details of its structure and mode of operation. The stylet actually has two distinct pieces, of two kinds of extracellular matrix (ECM): a sheet rolled into a tube with a sharp-pointed tip, and a sheet folded into a torus that fits into the proximal end of the tube to create a broadened base on which muscles and the male canal insert. The supporting rods are yet other phases of ECM in the mesenchyme. The six inner ones merge distally to ensheath the stylet, and that sheath bears five channels conducting the secretions of gland cells flanking the stylet to minute pores around the stylet tip. Confocal microscopy of the stylet apparatus in different phases of protrusion show that the outer rods are retracted from a protective position around the tip as the apparatus is protruded by protractors. The stylet is likely then protruded farther by contraction of the penis bulb, so that the stylet pore is exposed to allow the flow of secretions from the prostatic vesicle. The venom could be those secretions, as has been assumed, or secretions of the newly discovered gland cells of the inner mantle.

Pilot-scale steam aging of steel slags.

Solid waste management has gained importance in the steel industry in view of rising environmental concerns and scarcity of raw materials. In spite of significant developments in reducing waste generation and development of recycling technologies, steel slag is still a concern for the industry as most of it is dumped. Steel slag is similar to stone aggregates in strength, but its volumetric instability in contact with water hinders its application as aggregates in construction. A part of steel slag is normally exposed to rain and sun for natural aging and stabilization for months before use. The natural aging process is slow and time-consuming, and thus restricts its usage. The steelmaking slag can be put to effective use as coarse aggregates if quickly aged and stabilized by pre-reacting the free expansive phases. In the present work, a new process has been developed to accelerate the steel slag aging process using steam in a 30 T pilot scale facility. The setup has controlled steam injection, distribution, and process control system for steam, temperature, flow, and pressure. Steam percolates through the minute pores in the slag lumps and hydrates the expansive free lime and MgO phases, making it stable. The aged slag expansion properties were tested using an in-house developed expansion testing apparatus. The process is capable of reducing the expansion of steel slag from 3.5% to <1.5% (standard requirement) in 7 days. The aged steel slag is currently being used in roads at JSW Steel, Vijayanagar Works.

Adhesion of Trypanosoma Evansi to Red Blood Cells (RBCs): Implications in the Pathogenesis of Anaemia and Evasion of Immune System

Background: Trypanosoma evansi is the etiological agent of trypanosomosis, a disease of domestic (horses, cattle and goats) and wild (capybara, vampires) animals characterized by anaemia, degeneration, necrosis and inflammatory processes. This disease is of great concern because it produces growth retardation, loss of body weight, low production of animal proteins and diminished fertility and traction power. Because anaemia is considered the most characteristic symptom, the aim of this study was to assess the effects that T. evansi adhesion to erythrocytes has on their morphology, surface oligosaccharides profiles and trypanosome surface antigens. Methods: Blood and tissues samples from mice experimentally infected, were studied using scanning (SEM) and transmission (TEM) electron microscopes and lectin's histochemistry (sConA, sWGA, PNA, LFA, etc.). Furthermore immunoprecipitation of T. evansi radio iodinated surface antigens with specific anti-hosts and anti-trypanosome sera was performed and antigens analysed by electrophoresis and autoradiography. Results: T. evansi adhesion to erythrocytes as well as changes in the morphology of them, were frequent findings. SEM studies showed that adhesion of bloodstream trypomastigotes of T. evansi to mature erythrocytes and reticulocytes occurred through its flagellum, undulating membrane or cellular body and were mediated by filopodia. Minute pores and filamentous material were sometimes observed on erythrocytes membrane at the point of adhesion to the trypanosome. Oligosaccharides changes of RBCs glycocalix were characterized by a marked decrease in Man/Glc, terminal GalNAc and terminal Neu5Ac labelling accompanied by an increase in labelling of terminal GlcNAc. There were not labelling changes with the other lectins assayed. Preliminary immunoprecipitation studies of T. evansi radio iodinated surface antigens with anti-host sera, showed the presence of a of 45 kDa antigen from erythrocyte and host plasma on T. evansi plasma membranes. Furthermore, TEM studies demonstrated an increased abnormal erythrophagocytosis in adrenal gland, spleen and liver of experimentally infected mice. Conclusion: Adhesion of T. evansi to erythrocytes together with morphological and biochemical changes of these cells must be responsible for abnormally incremented erythrophagocytosis. On the other hand, detection of antigens from host on T. evansi membranes, suggests the operability of the antigen masking as an alternate immune response evasion mechanism to antigenic variation described in African trypanosomes.

The Life Cycle of Didymium laxifilum and Physarum album on Oat Agar Culture.

The plasmodial slime molds is the largest group in the phylum Amoebozoa. Its life cycle includes the plasmodial trophic stage and the spore-bearing fruiting bodies. However, only a few species have their complete life cycle known in details so far. This study is the first reporting the morphogenesis of Didymium laxifilum and Physarum album. Spores, from field-collected sporangia, were incubated into hanging drop cultures for viewing germination and axenic oat agar plates for viewing plasmodial development and sporulation. The spores of D.laxifilum and P.album germinated by method of V-shape split and minute pore, respectively. The amoeboflagellates, released from spores, were observed in water film. The phaneroplasmodia of two species developed into a number of sporangia by subhypothallic type on oat agar culture. The main interspecific difference of morphogenesis was also discussed.

Reevaluation of the plant “gemstones”: Calcium oxalate crystals sustain photosynthesis under drought conditions

ABSTRACTLand plants face the perpetual dilemma of using atmospheric carbon dioxide for photosynthesis and losing water vapors, or saving water and reducing photosynthesis and thus growth. The reason behind this dilemma is that this simultaneous exchange of gases is accomplished through the same minute pores on leaf surfaces, called stomata. In a recent study we provided evidence that pigweed, an aggressive weed, attenuates this problem exploiting large crystals of calcium oxalate as dynamic carbon pools. This plant is able to photosynthesize even under drought conditions, when stomata are closed and water losses are limited, using carbon dioxide from crystal decomposition instead from the atmosphere. Abscisic acid, an alarm signal that causes stomatal closure seems to be implicated in this function and for this reason we named this path “alarm photosynthesis.” The so-far “enigmatic,” but highly conserved and widespread among plant species calcium oxalate crystals seem to play a crucial role in the survival of plants.

Impact of Metallurgical and Mechanical Properties of Sintered Silver Joints on Die-Attach Reliability of High-Temperature Power Modules

Sintered silver bonding processes are expected to offer bonding solutions with high heat endurance for power modules using wide bandgap semiconductors. This study reports the die-attach reliability of the bonding process under thermal cycling tests, focusing on the metallurgical and mechanical properties of sintered silver joints. A nanocrystalline (NC) structure with 150-nm-sized grains was observed in the as-sintered state, while a coarsened structure with microsized grains and pore coalescence was observed after annealing at 350°C for 1 h. In addition, the increase of bonding pressure reduced the number of coarse pores. Transmission electron microscope observations showed favorable crystalline structure along the grain boundaries. Tensile tests at room and high temperature revealed that the sintered silver materials showed the inherent mechanical properties of NC metals. Thermal cycling tests of die-attached specimens demonstrated the temperature dependence of crack resistance at constant amplitude. Furthermore, coalescence of pores and coarsening of grains reduced bonding reliability. It can be inferred from the results that NC structure and minute pore dispersion improves bonding reliability.

Collaboration between Yamagata University and Kamo Aquarium – Rapid adaptive evolution of jellyfishes inhabiting marine lakes in Palau

The Palau Project Group at the Faculty of Science, Yamagata University, Japan has collaborated with the Tsuruoka City Kamo Aquarium, Yamagata, Japan since 2003. The Palau Islands include approximately 70 marine lakes formed by the rising of ancient coral reefs. In some marine lakes that are completely isolated from outer lagoons, seawater can soak through minute pores in the limestone surrounding the lakes, causing tidal changes to occur. However, marine organisms cannot enter or exit marine lakes. Based on our previous evolutionary genetic analyses, certain fish (in Atherinidae, Apogonidae, and Gobiidae) and mussels (in Mytilidae) exhibit distinct patterns of evolution between marine lake and outer lagoon populations, and also among marine lake populations. Dawson and Jacobs (2001) reported that three distinct species of moon jellyfishes are distributed in Palau; Aurelia sp. 3 and Aurelia sp. 6 inhabit outer lagoons and Aurelia sp. 4 inhabits marine lakes. We surveyed and collected jellyfish and confirmed that the species are highly differentiated both genetically and morphologically. Based on additional comparative observations of Aurelia sp. 4 and Aurelia sp. 3, the former clearly exhibits specific morphological and ethological characters adapted to the environmental conditions that characterize calm marine lakes. Based on geological estimates of marine lake formation, such adaptive evolution in jellyfish occurred rapidly between 5,000 and 15,000 years ago.