Eko Agus Suyono

Carapace surface architecture facilitates camouflage of the decorator crab Tiarinia cornigera.

UNLABELLED This paper elucidates the unique setal morphology of the decorator crab Tiarinia cornigera, and further presents evidence to that setal morphology promotes micro-organism nucleation and adhesion. The carapace of this crab is covered by clusters of setae, each comprising a hollow acicular stem that is enveloped by a haystack-like structure. Using computational fluid dynamics, we find that these setae are responsible for manipulating water flow over the carapace surface. Micro-organisms in the sea water, nest in areas of flow stagnation and as a result, nucleate to and biofoul the setae by means of chemical adhesion. Attached micro-organisms secrete extracellular polymeric substances, which we deduce must also provide an additional element of chemical adhesion to mechanically interlocked mesoscopic and macroscopic biomatter. By coupling physical and chemical methods for adhesion, T. cornigera is able to hierarchically decorate its carapace. STATEMENT OF SIGNIFICANCE Our paper brings to light the unique decorator crab carapace morphology of T. cornigera; and furthermore evidences its function in micro-organism nucleation and adhesion. We show how this special carapace morphology directs and guides water flow to form nesting regions of water stagnation where micro-organisms can nucleate and adhere. In the literature, decorator crab carapaces are presumed to be able to mechanically interlock biomatter as camouflage using hook-like setal outgrowths. T. cornigera contrarily exhibits clusters of hay-stack like structures. By encouraging micro-organism adhesion to the carapace setae, T. cornigera is able to effectively attach biomatter using both chemical and physical principles of adhesion. T. cornigera essentially has a super-biofouling carapace surface, for at least micro-organisms. Our work will have an impact on researchers interested in biofouling, adhesion, biomedical and purification filter systems, and in the development of novel biomimetic surfaces with tailored properties.

Solvent vapor treatment improves mechanical strength of electrospun polyvinyl alcohol nanofibers

Electrospun nanofibers of polyvinyl alcohol (PVA) have poor mechanical strength. As such their use has often been avoided, particularly in applications that require high mechanical properties. The objective of this study is to increase the mechanical properties of PVA nanofiber mats via physical crosslinking with solvent vapor treatment using organic solvents, dimethyl sulfoxide (DMSO), N, N-dimethyl formamide (DMF), and methanol. The effect of solvent vapor treatment on PVA nanofibers is clearly observed by scanning electron microscope (SEM). The tensile strength increased by over 60%, 90%, and 115% after solvent vapor treatment with DMF at a temperature of 40 °C for 2 h, 4 h, and 8 h, respectively, compared to untreated PVA nanofibers. In addition, Youngs modulus of PVA nanofiber mats also increased after DMF treatment. As a comparison, DMSO and methanol were also used in solvent vapor treatment because of differences in their polymer-solvent affinity. Results showed that the highest improvement (100%) in mechanical strength was obtained using DMF. This study shows that solvent vapor treatment offers a simple and inexpensive method that provides excellent results and is a promising alternative treatment for use in increasing the mechanical properties of electrospun nanofibers.

The Environment, Sustainability and Universities in Indonesia: An Examination of the Nexus

This chapter tries to understand the development and the shape of environmental and sustainability efforts by higher education institutions (HEIs) in Indonesia, with reference to the environment-sustainability nexus. It has found that the sustainability efforts by Indonesian HEIs have developed in a rather separate stream from long-standing environmental efforts, and they have yet to link up in many cases. The former is associated more with the initiatives at the national and international levels, while the latter has developed in an “ESD-ish” fashion by incorporating various social and economic elements at the local and national levels. On the one hand, this raises a questions about the rationale of imposing the novel concept of sustainability education/research or ESD when there already is a received concept (i.e. environmental education/research). On the other hand, this chapter argues for synergizing them, suggesting that community-level activities can serve as their meeting point.

Polyacrylonitrile Nanofiber-Based Quartz Crystal Microbalance for Sensitive Detection of Safrole

Safrole is the main precursor for producing the amphetamine-type stimulant (ATS) drug, N-methyl-3,4-methylenedioxyamphetamine (MDMA), also known as ecstasy. We devise a polyacrylonitrile (PAN) nanofiber-based quartz crystal microbalance (QCM) for detecting safrole. The PAN nanofibers were fabricated by direct electrospinning to modify the QCM chips. The PAN nanofiber on the QCM chips has a diameter of 240 ± 10 nm. The sensing of safrole by QCM modified with PAN nanofiber shows good reversibility and an apparent sensitivity of 4.6 Hz·L/mg. The proposed method is simple, inexpensive, and convenient for detecting safrole, and can be an alternative to conventional instrumental analytical methods for general volatile compounds.

Polyacrylonitrile nanofiber as polar solvent N,N-dimethyl formamide sensor based on quartz crystal microbalance technique

Here, we describe an N,N-dimethyl formamide (DMF) vapour sensor fabricated by coating polyacrylonitrile (PAN) nanofiber structured on quartz crystal microbalance (QCM). The PAN nanofiber sensors with an average diameter of 225 nm to 310 nm were fabricated via electrospinning process with different mass deposition on QCM substrate. The nanostructured of PAN nanofiber offers a high specific surface area that improved the sensing performance of nanofiber sensors. Benefiting from that fine structure, and high polymer-solvent affinity between PAN and DMF, the development of DMF sensors presented good response at ambient temperature. Since there is no chemical reaction between PAN nanofiber and DMF vapour, weak physical interaction such absorption and swelling were responsible for the sensing behavior. The results are indicating that the response of PAN nanofiber sensors has more dependency on the nanofiber structure (specific surface area) rather than its mass deposition. The sensor also showed good stability after a few days sensing. These findings have significant implications for developing DMF vapour sensor based on QCM coated polymer nanofibers.

A comparison of nutritional values of Kappaphycus alvarezii, Kappaphycus striatum, and Kappaphycus spinosum from the farming sites in Gorontalo Province, Sulawesi, Indonesia

Kappaphycus is a red alga which contains carrageenan. Kappaphycus alvarezii is the most popular seaweed known as cottoni in addition to several other species, such as K. spinosum (spinosum) and K. striatum (sacol). These three species of Kappaphycus were collected from farming sites of Kappaphycus in Popayato, Pohuwato district, Province of Gorontalo, Sulawesi, Indonesia. The nutritional values of these three Kappaphycus were assessed based on the analysis on their chemical composition, including ash, lipid, crude fiber, protein, carbohydrate, vitamin C, gel strength, and mineral contents including Ca, Na, and Fe, as well as fatty acids. There were no significant differences in the nutritional values of K. alvarezii, K. striatum, and K. spinosum from farming sites of Gorontalo Province, Sulawesi. However, K. alvarezii had the highest value of carbohydrate, protein, vitamin C, and gel strength, whereas K. spinosum had the highest contents of Ca, Na, and omega-6 fatty acids. Additionally, K. striatum had the highest moisture, crude fiber, Fe, and omega-3 fatty acid. It is suggested that each Kappaphycus is a potential source of important nutrition for human and animal health.

The effects of diatom pore-size on the structures and extensibilities of single mucilage molecules

Diatoms secrete extracellular polymeric substances (EPS), or mucilage, around the cell wall that may serve to aid in motility and form a discrete layer that may help maintain thicker layers of EPS that have a greater role in adhesion. Mucilage molecules adhere to the diatom frustules, which are biosilica skeletons that develop from the diatom cell walls. Here, molecular dynamics methods were used to determine the characteristics of mucilage molecules as a function of pore size; notably 1,4-α-D-galacturonic acid, 1,4-β-glucuronic acid and 1,4-β-D-mannuronic acid. These uronic acids differ from each other in structure and extensibility as a function of their folding characteristics. Here, we find that when overlain upon a pore, mucilage molecules try to return to their native folded states but are restrained by their interactions with the silica surfaces. Furthermore, the extensibility of mucilage molecules over pore spaces affects the extent of mechanical energy required to straighten them. As such, different EPS molecules will affect sliding, friction and adhesion to subsequent layers of EPS in different ways. We conclude that higher EPS extensibility is homonymous with higher adhesive or frictive resistance since the molecules will be able to strain more before they reach the most extended (and thus rigid) conformation. The research herein is applicable to modern engineering as it yields insight into the biomimetic design of molecules and surfaces for improved adhesion or motility.

Study of cultivation and growth rate kinetic for mixed cultures of local microalgae as third generation (G-3) bioethanol feedstock in thin layer photobioreactor

The increasing use of fossil fuels causes the depletion in supply and contributes to climate change by GHG emissions into the atmosphere. Microalgae indicate as renewable and sustainable energy sources as they have a high potential for producing large amounts of biomass for third-generation biofuels (bioethanol and biodiesel) feedstock. However, there are several parameters which should be considered for microalgae cultivation, such as environmental conditions, medium composition and microalgae species. The aim of this research was to study cultivation of mixed microalgae cultures (Glagah consortium and Arthrospira maxima) in a thin layer photobioreactor. Farmpion medium, Bolds Basal Medium (BBM) and Thoriq Eko Arief (TEA) medium were investigated as cultivation medium for bioethanol feedstock for 7 days. The results showed that the highest dry weight concentration of microalgae was in Farmpion medium (0.35 mg/ml) and the highest carbohydrate concentration of microalgae was in BBM (0.14 mg/ml). Thus, the optimum medium of microalgae cultivation for bioethanol feedstock was BBM because of the highest carbohydrate-dry weight ratio (0.88). In addition, mathematical approach by using Contois model was used to find out the growth rate of microalgae cultivation in each medium.

Effect High Salinity and Red-Blue Light Treatment on Lipid Content of the Microalgae Chlorella zofingiensis Dönz as Biodiesel Source

Chlorella zofingiensis Dönz is not only known as feed in aquaculture industry, but also it has been developed as biodiesel source. In order to optimize the microalgae as a biodiesel feedstock, it is necessary to study its environmental factors, such as light and medium salinity. This study was conducted to determine the effect of red-blue light in a wide range of salinity medium. C. zofingiensis Dönz used in this study were cultured for 21 days on a laboratory scale using a medium consisted of ZA, Urea and Farmpion (local agriculture fertilizer) with a ratio of 4: 2: 1. There were three variations of salinity treatments, including culture without the addition of NaCl (its medium salinity was 14 ppm); the addition of NaCl 5 ppm (its medium salinity was 19 ppm) and NaCl 10 ppm (its medium salinity was 24 ppm). Its cell density and dry weight were measured every 7 days. Neutral lipid content was determined with Nile Red staining method and analyzed with CellProfiler software every 7 days. The highest lipid content was achieved by treatment of blue light and the addition of NaCl 5 ppm, accounted for 344.6 mg L-1 or 50% of the dry weight.

Assessment of sequence variation from SIT1 gene on diatom (Bacillariophyceae) using in silico PCR

Diatoms are widely known as brown microalgae generating silicified cell-wall called frustule. The unique frustule ornamentations form occlusion and perforation. An interesting study of frustule formation led us to understand further the variation of thegene of interest (Silicic Acid Transporter/ SIT1) on Bacillariophyceae. The SIT1 gene indicating the frustule formation on diatomhas been studied. As a preliminary study, we used in silico Polymerase Chain Reaction (PCR) analysis to know the gene variation of SIT1. The analysis was conducted using data available from Genebank followed by primer design, comparison of sequence alignment, and in silico PCR. Fourteen extracted SIT1 sequences were aligned and analyzed usingFastPCR program with in silico PCR feature. Our result suggested the primer 7C could be implemented as degenerate primers resulting the in silico amplification of 426-435 bp PCR products. MUSCLE algorithm was furthermore used to align the regions resulted from in silico PCR. A moderate percent...