Antonia Morita Iswari Saktiawati, Kuwat Triyana, Siska Dian Wahyuningtias, Bintari Dwihardiani, Trisna Julian, Shidiq Nur Hidayat, Riris Andono Ahmad, Ari Probandari, Yodi Mahendradhata

https://doi.org/10.1371/journal.pone.0249689

Journal : PLOS ONE

Volume 16, April 2021, 0249689

Abstract

Even though conceptually, Tuberculosis (TB) is almost always curable, it is currently the world’s leading infectious killer. Patients with pulmonary TB are the source of transmission. Approximately 23% of the world’s population is believed to be latently infected with TB bacteria, and 5–15% of them will progress at any point in time to develop the disease. There was a global diagnostic gap of 2.9 million between notifications of new cases and the estimated number of incident cases, and Indonesia carries the third-highest of this gap. Therefore, screening TB among the community is of great importance to prevent further transmission and infection. The electronic nose for screening TB (eNose-TB) project is initiated in Yogyakarta, Indonesia, to screen TB by breath test with an electronic-nose that is easy-to-use, point-of-care, does not expose patients to radiation, and can be produced at low cost.

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Sudarmaji Saroji, Ekrar Winata, Putra Pratama Wahyu Hidayat, Suryo Prakoso, Firman Herdiansyah

DOI: 10.13170/aijst.10.1.18749

Journal : Aceh International Journal of Science and Technology

Volume 10, April 2021, 9-17

Abstract

Lithofacies classification is a process to identify rock lithology by indirect measurements. Usually, the classification is processed manually by an experienced geoscientist. This research presents an automated lithofacies classification using a machine learning method to increase computational power in shortening the lithofacies classification process’s time consumption. The support vector machine (SVM) algorithm has been applied successfully to the Damar field, Indonesia. The machine learning input is various well-log data sets, e.g., gamma-ray, density, resistivity, neutron porosity, and effective porosity. Machine learning can classify seven lithofacies and depositional environments, including channel, bar sand, beach sand, carbonate, volcanic, and shale. The classification accuracy in the verification phase with trained lithofacies class data reached more than 90%, while the accuracy in the validation phase with beyond trained data reached 65%. The classified lithofacies then can be used as the input for describing lateral and vertical rock distribution patterns.

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Edi Suharyadi, Sri Handika Pratiwi, I Putu Tedy Indrayana, Takeshi Kato, Satoshi Iwata, Keisuke Ohto

https://doi.org/10.1088/2053-1591/abe986

Journal: Materials Research Express

Volume 8, March 2021, 036101

Abstract

Zn-Ni ferrite nanoparticles were successfully synthesized by coprecipitation method. The samples were annealed at various temperatures, i.e., 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C. The nanoparticles have the mixed spinel phase structure as confirmed by the X-ray diffraction patterns. The crystallite size was 15.1 nm and increased to 25.1 nm after annealing at 1000 °C. Transmission electron microscope images showed that the annealed sample exhibited better dispersion and grain boundaries compared to the as-prepared sample. Fourier transform infra-red spectra showed the existence of vibrations at 378 cm−1 and 555 cm−1, confirming bonding for mixed spinel ferrites. The hysteresis measurement by using vibrating sample magnetometer confirmed that the sample possessed soft magnetic properties with a coercivity of 45 Oe and increased after annealing. The saturation magnetization of the as-prepared sample was 11 emu g−1, and increased to 58 emu g−1 after annealing at a temperature of 800 and 1000 °C. The specific absorption rate (SAR)with an alternating current magnetic field (50 Hz and 100 Oe) of Zn-Ni ferrite before and after annealing (at 800 °C) was 63.7 and 92.4 mW g−1, respectively. The results showed that annealing temperature has a significant role in determining the microstructural, the magnetic properties and the SAR of the nanoparticles.

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Juharni, Ilyas Maulana Yahya, Edi Suharyadi, Takeshi Kato, Satoshi Iwata

Journal : International Journal of Nanoelectronics and Materials

Vol. 14, January 2021, 209

Abstract

The purpose of this study is to enhance the sensitivity of Surface Plasmon Resonance (SPR) sensor using coreshell Fe3O4@Ag nanoparticles (NPs). Fe3O4@Ag NPs were synthesized by co-precipitation method with various concentration of Ag as a shell. The crsytal structure of Fe3O4 corresponds to the cubic inverse spinel structure. The particle size of Fe3O4@Ag NPs with Ag concentration of 40mM is 13.8 nm. The saturation magnetization (Ms), and coercivity field (Hc) of Fe3O4@Ag NPs with Ag concentration of 20mM is 52.9 emu/g and 157.2 Oe, respectively, and then decreased with the increase of Ag concentration. An intensity of absorption peak increased with the increase of Ag concentration. A spherical nanoparticle consisting of a spherical Fe3O4 core covered by an Ag shell, was used as an active material to increase the signal detection of SPR, with a wavelength of 632.8 nm in the Kretschmann configuration. The system consists of a three-layer materials, i.e., prism/Au/Fe3O4@Ag NPs. The results show that the SPR angle shifted to the larger angle of incident light by using Fe3O4@Ag NPs and the addition of a core-shell in the conventional SPR-based biosensor leads to the enhancement of the SPR biosensor sensitivity.

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Idham Syah Alam

Journal : Journal of Physics G: Nuclear and Particle Physics
Volume 49 Number 2 025002

Abstract

We investigate a left–right mirror model with SU(3)_c × SU(2)_L × SU(2)_R × U(1)_Y and a discrete  symmetry, which introduces mirror fields that are copies of the standard model (SM) fields. The mirror fields have the opposite chirality to their SM counterpart fields. We also introduce singlet scalars as dark matter (DM). The new interaction between DM, SM fermions, and mirror fermions can account for DM abundance, charged lepton flavor violation, lepton anomalous magnetic moment, and flavor changing neutral current. We demonstrated that if we choose DM annihilation into muon as the dominant annihilation channel for leptophilic DM, both the observed DM abundance and the observed discrepancy between theory and experiment in the muon anomalous magnetic moment can be explained without contradicting the bound derived from charged lepton flavor violating processes. We briefly discuss how mirror fermions will be produced at the future linear collider, as mirror fermions can interact with neutral gauge bosons in this model. Finally, we discuss the lightest mirror neutrino decay mechanism, which will be highly abundant if stable.

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Fika Fauzi, Aditya Rianjanu, Iman Santoso, Kuwat Triyana

https://doi.org/10.1016/j.sna.2021.112837
Journal : Sensors and Actuators A: Physical
Volume 330, 15 October 2021, 112837

Abstract

Graphene and graphene-based materials have shown great potential for detecting gases and humidity due to their high specific surface areas. Quartz crystal microbalance (QCM) sensors have been massively developed because they have high sensitivity, consume low energy, and can be readily modified. Recently, QCM coated by graphene composites has been explored to sensitively and selectively detect various gases and humidity. Herein, we summarize the recent progress on QCM gas sensors and QCM humidity sensors based on graphene materials and graphene composites. We start from an introduction to the sensing principle of QCM, synthesis and preparation of graphene materials used for QCM sensing material, application of graphene materials and graphene composites for sensing materials of QCM gas sensors and humidity sensors, and the mechanism of those sensors. We mainly summarize the recent advances in the performances of QCM gas sensor and QCM humidity sensor coated with pristine graphene, graphene oxide, reduced graphene oxide, and various graphene-based composite materials, including chemical, polymer, metal oxide, and other carbon-based materials. The challenges for future works related to the development of QCM sensors coated by graphene materials or graphene composites are also elaborated.

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Aditya Rianjanu, Eka Nurfani, Muhamad F. Arif, Kuwat Triyana, Hutomo Suryo Wasisto

https://doi.org/10.1016/j.mtcomm.2020.101770
Journal : Materials Today Communications

Abstract

Stability is one of the crucial sensor properties to be applicable in real condition and yet hardly investigated. In this communication, we evaluated the stability of butanol vapor sensors that were constructed using quartz crystal microbalance (QCM) platforms coated with electrospun polyvinyl acetate (PVAc) nanofibers. The reliability test was performed by monitoring the sensor frequency characteristics in a long-term measurement, in which the frequency shift was found to decrease by ∼7% after the sensors have been tested for 100 times. This performance degradation was mainly attributed to the reduction of active membrane surface area caused by swelling of the nanofibers, which was confirmed by scanning electron microscopy (SEM) images. This finding does not only allow us to better understand the nanofiber-coated QCM sensor limitation and degradation process, but also to design appropriate strategies for mitigating the device stability issues.

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Nursidik Yulianto, Andam Deatama Refino, Alina Syring, Nurhalis Majid, Shinta Mariana, Patrick Schnell, Ruri Agung Wahyuono, Kuwat Triyana, Florian Meierhofer, Winfried Daum, Fatwa F. Abdi, Tobias Voss, Hutomo Suryo Wasisto & Andreas Waag

https://doi.org/10.1038/s41378-021-00257-y
Journal : Nature Microsystems & Nanoengineering

Abstract

The integration of gallium nitride (GaN) nanowire light-emitting diodes (nanoLEDs) on flexible substrates offers opportunities for applications beyond rigid solid-state lighting (e.g., for wearable optoelectronics and bendable inorganic displays). Here, we report on a fast physical transfer route based on femtosecond laser lift-off (fs-LLO) to realize wafer-scale top–down GaN nanoLED arrays on unconventional platforms. Combined with photolithography and hybrid etching processes, we successfully transferred GaN blue nanoLEDs from a full two-inch sapphire substrate onto a flexible copper (Cu) foil with a high nanowire density (~107 wires/cm2), transfer yield (~99.5%), and reproducibility. Various nanoanalytical measurements were conducted to evaluate the performance and limitations of the fs-LLO technique as well as to gain insights into physical material properties such as strain relaxation and assess the maturity of the transfer process. This work could enable the easy recycling of native growth substrates and inspire the development of large-scale hybrid GaN nanowire optoelectronic devices by solely employing standard epitaxial LED wafers (i.e., customized LED wafers with additional embedded sacrificial materials and a complicated growth process are not required).

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Aditya Rianjanu, Rizky Aflaha, Nur Istiqomah Khamidy, Mitra Djamal, Kuwat Triyana and Hutomo Suryo Wasisto

https://doi.org/10.1039/D1MA00152C
Journal : MATERIALS ADVANCES

Abstract

Conventional chemoresistive gas sensors based on inorganic metal oxide semiconductors work typically at an elevated temperature (200 – 500°C) to facilitate the chemical reaction between the target gas molecules and sensing oxide layer. Besides their high operating temperature, these sensors are often found to possess poor selectivity towards a specific analyte. Here, we report on the fabrication and functionalization of electrospun citric acid-doped polyvinyl acetate (PVAc/CA) nanofibers on a quartz crystal microbalance (QCM) chip, which is used as a highly sensitive and selective gravimetric trimethylamine (TMA) gas sensor operating at room temperature. The structural morphology and chemical composition of both undoped and CA-doped PVAc nanofibers were investigated by the scanning electron microscopy (SEM) and the Fourier-transform infrared (FTIR) spectroscopy, respectively. During exposure to TMA vapors, the PVAc/CA nanofiber sensor could obtain a sensing sensitivity of 85.4 Hz/ppm with a limit of detection (LOD) of 19 ppb. Cross-sensitivity tests involving different analytes/gases (i.e., TMA, dimethylamine (DMA), methylamine (MA), ammonia, and water) revealed the high selectivity characteristic of the sensor towards TMA molecules. Besides, decent reversibility and repeatability of the sensor with response and recovery times of 7 and 20 s, respectively, were also demonstrated. Amongst the other recently reported QCM-based TMA gas sensors, the proposed device is superior in terms of sensitivity and LOD. This simple yet low-cost alternative improvement technique based on chemical modification of nanofibers can potentially be employed in food-freshness monitoring system, especially for fishery and seafood products where TMA is employed as their quality indicator (i.e., the primary marker of the fishy odor).

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Antonia Morita Iswari Saktiawati, Kuwat Triyana, Siska Dian Wahyuningtias, Bintari Dwihardiani, Trisna Julian, Shidiq Nur Hidayat, Riris Andono Ahmad, Ari Probandari, Yodi Mahendradhata

https://doi.org/10.1371/journal.pone.0249689
Journal : PLOS One

Abstract

Even though conceptually, Tuberculosis (TB) is almost always curable, it is currently the world’s leading infectious killer. Patients with pulmonary TB are the source of transmission. Approximately 23% of the world’s population is believed to be latently infected with TB bacteria, and 5–15% of them will progress at any point in time to develop the disease. There was a global diagnostic gap of 2.9 million between notifications of new cases and the estimated number of incident cases, and Indonesia carries the third-highest of this gap. Therefore, screening TB among the community is of great importance to prevent further transmission and infection. The electronic nose for screening TB (eNose-TB) project is initiated in Yogyakarta, Indonesia, to screen TB by breath test with an electronic-nose that is easy-to-use, point-of-care, does not expose patients to radiation, and can be produced at low cost.

read more