Analisis Resistansi Pentanahan Pada Menara Transmisi 150 kV Jalur Maros – Sungguminasa

Sistem pentanahan merupakan salah satu faktor penting dalam usaha pengamanan dan perlindungan sistem tenaga listrik. Pada saat terjadi gangguan disistem tenaga listrik, sistem pentanahan dapat menyalurkan arus gangguan dengan cepat ke dalam tanah dan disebarkan ke segala arah. Saluran Udara Tagangan Tinggi (SUTT) pada jalur Maros - Sungguminasa merupakan jalur yang letak towernya berada pada jenis tanah yang berbeda – beda, sehingga membuat penulis mengambil jalur Saluran Udara Tegangan Tinggi (SUTT) Maros - Sungguminasa untuk menjadi tempat penelitian. Metode penelitian yang digunakan adalah metode studi literatur, observasi, wawancara, dan analisis data. Setelah memperoleh data hasil pengukuran nilai resistansi pentanahan tower transmisi 150 kV Maros - Sungguminasa, didapatkan nilai tahanan pentanahan pada tanah rawa sebesar 1, 33 Ω, dan pada tanah liat sebesar 1, 35 Ω. Selanjutnya menghitung persentase perbandingan antara data hasil pengukuran dengan standar yang telah ditentukan, didapatkan presentase perbandingan nilai rata - rata tahanan pentanahan di tanah liat dengan standar adalah 13,5% dan persentase perbandingan nilai rata - rata tahanan pentanahan di tanah rawa dengan standar adalah 13,3%. Maka dari kedua hasil tersebut, dapat diketahui bahwa nilai tahanan pentanahan di tanah rawa lebih baik dibandingkan nilai tahanan pentanahan di tanah liat dengan persentase perbandingan sebesar 13, 3% untuk tanah rawa

Sound Correspondences of Modern Standard Arabic Moroccan Arabic and Najdi Arabic

This paper studies the process of sound correspondences that occur in Modern Standard Arabic (MSA), Moroccan Arabic (MAR), and Najdi Arabic (NAR). It attempts to find answers for the following questions: a) What are the identical word pairs, words couples that have a phonemic correspondence, a phonetic similarity, and a pair of words that contains difference of one phoneme, b) What are the process of morphophonemic in the form of assimilation, metathesis, and epenthesis. It is addressed to portray the process of morphophonemic assimilation, metathesis and epenthesis in three Arabic languages using Crowley’s theory. This study used 207 of Morris Swadesh's basic vocabulary as the key standard procedure for collecting data. The criteria adopted to analyze the data were orthographic, sound-change, phonological, and morpheme contrast. This research used descriptive qualitative method. The source of the data was basic-word vocabulary. The data were gathered from three dictionaries as sources to get information. The data were analyzed by using structural linguistics, especially phonology, morphology, and semantics. This investigation informed several aspects of findings such as identifying prefixes, suffixes, assimilation, metathesis, and epenthesis. Using the Swadesh vocabulary list, the results of this study found 207 vocabularies for each language. By analyzing parts of speech, it was found that these vocabularies can be classified into five-word classes, namely, nouns, pronouns, verb, adjectives, adverbs, and determiners

Self-assembly of minimal peptoid sequences

Peptoids are biofunctional N-substituted glycine peptidomimics. Their self-assembly is of fundamental interest because they demonstrate alternatives to conventional peptide structures based on backbone chirality and beta-sheet hydrogen bonding. The search for self-assembling, water-soluble “minimal” sequences, be they peptide or peptidomimic, is a further challenge. Such sequences are highly desired for their compatibility with biomacromolecules and convenient synthesis for broader application. We report the self-assembly of a set of trimeric, water-soluble α-peptoids that exhibit a relatively low critical aggregation concentration (CAC ∼ 0.3 wt %). Cryo-EM and angle-resolved DLS show different sequence-dependent morphologies, namely uniform ca. 6 nm wide nanofibers, sheets, and clusters of globular assemblies. Absorbance and fluorescence spectroscopies indicate unique phenyl environments for π-interactions in the highly ordered nanofibers. Assembly of our peptoids takes place when the sequences are fully ionized, representing a departure from superficially similar amyloid-type hydrogen-bonded peptide nanostructures and expanding the horizons of assembly for sequence-specific bio- and biomimetic macromolecules

Chain-end modifications and sequence arrangements of antimicrobial peptoids for mediating activity and nano-assembly

Poly(N-substituted glycine) “peptoids” are an interesting class of peptidomimics that can resist proteolysis and mimic naturally found antimicrobial peptides (AMPs), which exhibit wide spectrum activity against bacteria. This work investigates the possibility of modifying peptoid AMP mimics (AMPMs) with aliphatic lipid “tails” to generate “lipopeptoids” that can assemble into micellar nanostructures, and evaluates their antimicrobial activities. Two families of AMPMs with different distributions of hydrophobic and cationic residues were employed—one with a uniform repeating amphiphilicity, the other with a surfactant-like head-to-tail amphiphilicity. To further evaluate the interplay between self-assembly and activity, the lipopeptoids were variously modified at the AMPM chain ends with a diethylene glycol (EG2) and/or a cationic group (Nlys-Nlys dipeptoid) to adjust amphiphilicity and chain flexibility. Self-assembly was investigated by critical aggregation concentration (CAC) fluorescence assays and dynamic light scattering (DLS). The structure of a key species was also verified by small-angle X-ray scattering (SAXS) and cryo-electron microscopy (cryo-EM). To screen for antibacterial properties, we measured the minimum inhibitory concentrations (MIC) against S. aureus, E. coli, and P. aeruginosa. We found that certain combinations of lipid tail and AMPM sequences exhibit increased antibacterial activity (i.e., decreased MICs). Perhaps counter-intuitively, we were particularly interested in increased MICs in combination with low CACs. Concealing antimicrobial interactions due to packing of AMPMs in nano-assemblies could pave the way to AMPMs that may be “inert” even if unintentionally released and prevent microbes from gaining resistance to the lipopeptoids. Overall, incorporation of EG2 significantly improved lipopeptoids packing while the hydrophobic tail length was found to have a major influence over the MIC. One particular sequence, which we named C15-EG2-(kss)4, exhibited a very low CAC of 34 μM (0.0075 wt.%) and a significantly increased MIC above values for the unmodified AMPM. With the sequence design trends uncovered from this study, future work will focus on discovering more species such as C15-EG2-(kss)4 and on investigating release mechanisms and the potency of the released lipopeptoids

PERENCANAAN PEMBANGUNAN GEDUNG LABORATORIUM STRUKTUR FAKULTAS TEKNIK UNIVERSITAS SRIWIJAYA

Perancangan suatu gedung harus diperhitungkan secara matang dan menggunakan material yang baik. Hal ini dikarenakan bangunan gedung akan digunakan dalam kurun waktu yang panjang dan digunakan oleh banyak orang. Perancangan yang matang akan menghasilkan bangunan yang kuat, aman dan nyaman dengan persyaratan yang telah ditetapkan. Pengolahan data perencanaan ini menggunakan SAP v21 ultimate untuk menghitung pembebanan pada portal serta merencanakan dimensi balok maupun kolom. Berdasarkan dari perhitungan, dapat disimpulkan pada pembangunan gedung Laboratorium Struktur Fakultas Teknik Universitas Sriwijaya ini dibangun diatas tanah seluas 49 x 37 m yang memiliki 3 lantai dan menggunakan pondasi tiang pancang. Dari hasil perhitungan struktur yang berpedoman kepada Standar Nasional Indonesia (SNI) yang berlaku, didapatkan hasil untuk pondasi tiang pancang digunakan tiang persegi dengan dimensi 40 x 40 cm, dimensi sloof 30 x 60 cm, dimensi kolom 60 x 60 cm, dimensi balok anak 25 x 50 cm, dimensi balok induk 30 x 60 cm dan tebal pelat 12 cm. Berdasarkan perhitungan yang telah dilakukan maka dapat disimpulkan bahwa struktur pada gedung ini aman dan stabil

Crystallization and lamellar nanosheet formation of an aromatic dipeptoid

An aromatic peptoid analogue of the diphenylalanine dipeptide self-assembles in aqueous solution and the first crystal structure was obtained for this class of compound. This reveals molecular packing stabilized by networks of hydrogen bonds. Free-floating nanosheet lamellar structures are observed in solution, which form via cooperative intermolecular interactions driven by π stacking

Surface design for immobilization of an antimicrobial peptide mimic for efficient anti‐biofouling

Microbial surface attachment negatively impacts a wide range of devices from water purification membranes to biomedical implants. Mimics of antimicrobial peptides (AMPs) constituted from poly(N‐substituted glycine) "peptoids" are of great interest as they resist proteolysis and can inhibit a wide spectrum of microbes. We investigate how terminal modification of a peptoid AMP‐mimic and its surface immobilization affect antimicrobial activity. We also demonstrate a convenient surface modification scheme for enabling alkyne‐azide "click" coupling on amino‐functionalized surfaces. Our results verified that the N‐ and C‐terminal peptoid structures are not required for antimicrobial activity. Moreover, our peptoid immobilization density and choice of PEG tether resulted in a "volumetric" spatial separation between AMPs that, compared to past studies, enabled the highest AMP surface activity relative to bacterial attachment. Our analysis suggests the importance of spatial flexibility for membrane activity and that AMP separation may be a controlling parameter for optimizing surface anti‐biofouling

Correction to "self-assembly of minimal peptoid sequences"

It has come to our attention that some of our cryo-electron microscopy (cryo-EM) images actually show ice contamination, (1) instead of the soft matter aggregates originally indicated in our publication. The images only relate to counterexample peptoid sequences that did not properly assemble (originally Figures 3D–K and S5E–G, I–M, and P). As such, our main finding of an ultrashort water-soluble tripeptoid assembling into ordered nanofibers is not changed. Our overall conclusions based on complementary cryo-EM, DLS, CAC, and fluorescence spectroscopy measurements are also unaffected. Nonetheless, the figures indicated and associated text require correction. In re-examining our cryo-EM data set, we found micrographs showing additional structures that are unlikely to be contaminants, which we previously took as less representative. Like the artifacts, the structures now identified are also irregular and consist of an ensemble of sizes centered around a mean. Incidentally, the mean sizes of these structures (50–250 nm in diameter, depending on sequence) fit better with our complementary DLS results—no agglomeration effect of individual 5–20 nm ice artifacts is needed anymore to reconcile the sizes measured by EM and DLS

Mineralizing Coating on 3D Printed Scaffolds for the Promotion of Osseointegration

Design and fabrication of implants that can perform better than autologous bone grafts remain an unmet challenge for the hard tissue regeneration in craniomaxillofacial applications. Here, we report an integrated approach combining additive manufacturing with supramolecular chemistry to develop acellular mineralizing 3D printed scaffolds for hard tissue regeneration. Our approach relies on an elastin-like recombinamer (ELR) coating designed to trigger and guide the growth of ordered apatite on the surface of 3D printed nylon scaffolds. Three test samples including a) uncoated nylon scaffolds (referred to as “Uncoated”), b) ELR coated scaffolds (referred to as “ELR only”), and c) ELR coated and in vitro mineralized scaffolds (referred to as “Pre-mineralized”) were prepared and tested for in vitro and in vivo performance. All test samples supported normal human immortalized mesenchymal stem cell adhesion, growth, and differentiation with enhanced cell proliferation observed in the “Pre-mineralized” samples. Using a rabbit calvarial in vivo model, ‘Pre-mineralized’ scaffolds also exhibited higher bone ingrowth into scaffold pores and cavities with higher tissue-implant integration. However, the coated scaffolds (“ELR only” and “Pre-mineralized”) did not exhibit significantly more new bone formation compared to “Uncoated” scaffolds. Overall, the mineralizing coating offers an opportunity to enhance integration of 3D printed bone implants. However, there is a need to further decipher and tune their immunologic response to develop truly osteoinductive/conductive surfaces

Rooftop PV with battery storage solar smoother

© 2014 IEEE. Utilities are becoming concern about the increasing number of solar panels feeding unstable power into generator-based mini-grids particularly in rural locations. When the mini-grid experiences large changes in the injection of solar power, for example on cloudy days, the generators have to work hard to keep up. This paper recommends inclusion of battery storage (BS) solar smoother across terminals of existing rooftop PVs to compensate fluctuations in active output power due to environmental factors such as passing clouds and variations in solar radiation. A BS energy management strategy (BS-EMS) will be implemented to control the solar smoother and regulate the voltage at point of common coupling (PCC) while providing the grid with constant output power profile during daylight. A simple approach is also introduced and implemented to estimate battery rating based on typical measured PV characteristics