Sample Ability Research Articles

Multi-level hollow sphere rich in heterojunctions with dual function: Efficient microwave absorption and antiseptic

Effective electromagnetic wave absorption is now possible thanks to the design of the dielectric-magnetic double loss mechanism and the rich heterogeneous structure. In this study, hollow carbon spheres with rich heterostructures were synthesized using an easy and effective in situ growing approach. In addition to improving impedance matching, the hollow structure also reduces material density and weight. By modifying the load, this system can alter the dielectric characteristics of MXene, which in turn affects the sample's ability to absorb electromagnetic waves. MXene and the carbon material create a thick conductive network during the whole electromagnetic wave absorption process, creating the ideal environment for conduction loss. The sample's ability to attenuate electromagnetic waves is further improved by the interfacial polarization that the rich heterogeneous structure can produce. Co-magnetic nanoparticle nanoparticles are the main source of magnetic loss. The MXene@Co/C-100–800 (MCC-100–800) exhibits excellent electromagnetic wave absorption performance under the synergy of multiple loss mechanisms, with the maximum effective absorption bandwidth (EABmax) reaching 7.20 GHz and the minimum reflection loss (RLmin) being –53.99 dB at 2.10 mm. Finally, this work is guided by the coating engineering of MXene and provides new ideas for the rational design of heterostructures of nanomaterials.

Hydrogel based on patch halloysite nanotubes: A rheological investigation

The rheological behaviour of Patch halloysite nanotubes (PT_Hal) was investigated here. Their peculiar morphology shows longer and thinner nanotubes and gives rise to the formation of gel-like systems that are not evidenced in halloysite from other natural sources. According to frequency sweep tests, PT_Hal possesses solid-like characteristics even at low concentrations, suggesting that the material is highly structured. Interestingly, flow ramp analysis evidenced two distinct behaviours based on the clay concentration: a yield stress was detected only from 0.75 wt%, indicating the sample's ability to resist deformation or breaking. Furthermore, the study investigated the influence of ionic strength, revealing that the addition of salt did not significantly affect the gel's properties of this clay. Accordingly, in this work we propose a new hydrogel system based on green nanoclays that can be suitable for industrial and biological applications as well as for cultural heritage.

PENGUJIAN TEGANGAN TEMBUS KABEL NYA INSTALASI LISTRIK TEGANGAN RENDAH

This research examines the breakdown voltage on low voltage cables, by testing the voltage to breakdown and insulation resistance on low voltage cables. The purpose of this study was to determine the maximum limit of the cable sample's ability to receive injection voltage before experiencing an electric breakdown and the impact on insulation resistance and cable leakage current when given a voltage exceeding normal voltage and then to analyze the highest voltage that the cable can withstand in a certain time. The parameters used in the research design are insulation resistance and leakage current. The test was carried out at the High Voltage Laboratory, State University of Gorontalo with a high voltage tester HV transformer brand Terco Sweden with specifications for a maximum voltage capacity of up to 100 kV. The cable samples used were NYA 2x2.5 cables with the brands eterna, suprime and sigeru.

Analysis of heavy metal content and microbiological quality of fish and giant prawns chatch in Percut Watershed, Percut Sei Tuan District, Province of North Sumatra

The purpose of this research was to determine the content of heavy metals and microbiological quality, and compare to the requirements of the quality standard values according to SNI 2729:2013 and SNI 2705:2014, as well as to determine the value of the Bioaccumulation Factor (BAF) and the maximum consumption limit of fish and giant prawns heavy metal-concentrated. This researh used survey and random sampling methods, i.e taking research samples (tilapia, broom fish, and giant prawns) at 3 (three) observation stations, including Station 1 Amplas, Station 2 Denai, and Station 3 Percut. Heavy metal content (Pb and Cd) and microbiological quality (E.coli and Salmonella, sp) were analysed. Data analysis was done by inference and calculated using Microsoft office Excel (Microsoft Inc., USA) descriptively. The results showed that all samples in each observation did not meet the quality standard value requirements according to SNI 2729:2013 and SNI 2705:2014. The average heavy metal content of Lead (Pb) was 0,3 mg/kg in tilapia and broom fish, and 0,5 mg/kg in giant prawns. The content of heavy metal Cadmium (Cd), were 0,1 mg/kg in tilapia and broom fish, and 0,5 mg/kg in giant prawns. All samples also showed positive in containing E.coli and Salmonella, sp. The value of Bioaccumulation Factor (BAF) of heavy metals (Pb and Cd) in all samples was 1, meaning that the sample's ability to accumulate heavy metals (Pb and Cd) was high. The maximum limit for consumption of concentrated samples of heavy metals in tilapia was 0,196 kg/week, broom fish was 0,221 kg/week, and giant prawns was 0,203 kg/week.

Perception analysis of students' level of understanding in statistics course

Statistical courses are mandatory for students to take to assist in solving research problems. The purpose of this study was to determine student perceptions of the level of understanding of all statistical material indicators after attending statistics lectures and to prove that the average student perception was not in the low category. The research method used is quantitative research. The sample used was 31 samples from students of Early Childhood Education Teacher Education, Universitas Negeri Medan in 2021. The data collection technique used a questionnaire technique. Data were analyzed using descriptive statistics and one sample t-test. The results showed that Student perceptions of mastery of statistical lecture indicators fall into two categories, namely the high category of 61% and the medium category of 39%. The perception of the sample's ability to master the lecture indicators is divided into four categories, namely the very high category of 19%, the high category of 42%, the medium category of 32%, and the low category of 7%. The mean score of perceived mastery of statistical indicators is greater than 31.5, which means that students' perceptions of ability are not in the Low category.

Sodium dodecatungstophosphate hydrate-filled polymer composites for nuclear radiation shielding

This work is part of an ongoing project to produce environmentally friendly alternative radiation shielding materials for ionizing radiation facilities such as medical and industrial areas. As a new shield, a series of Sodium Dodecatungstophosphate Hydrate (Na3PO4.12WO3.H2O) doped polymer composite materials with different additives have been successfully produced. The hypothesis is highlighted by the positive effect of Na3PO4.12WO3.H2O supplement for nuclear radiation shield efficiency. The nuclear shielding performance of the new polymer composite materials produced was calculated using the WinXcom theoretical program at different energies. The results obtained were compared with the results calculated using the MCNP-X simulation program. In addition, a wide range of shielding parameters for gamma, neutron, proton and alpha radiation. For gamma radiation, mass attenuation coefficients (μm), half value layer (HVL), tenth value layer (TVL), mean free path (MFP), linear attenuation coefficients (LAC), effective atomic number (Zeff), exposure (EBF) and energy absorption buildup factors (EABF), dose multiplication factor (K(E,X)), the radiation protection efficiency (RPE) were evaluated; for neutron radiation, fast neutron removal cross sections (ΣR) was calculated; for proton and alpha radiation, Proton mass stopping power (ΨP), proton projected range (PR - ΦP), alpha mass stopping power (ΨA) and alpha projected range (PR - ΦA) have been determined. Among the mentioned shielding parameters, lower values of HVL, TVL, MFP, EBF, EABF, MSP, PR and high μm, Zeff, ΣR imply that the composite material has better shielding properties. According to the obtained results, it is reported that the NPW20 coded sample's ability to attenuate gamma and charged particle radiation more efficiently than that of other prepared composites. NPW05 coded sample was found to be more suitable for neutron shielding capability.

Suppression of surface recombination in surface plasmon coupling with an InGaN/GaN multiple quantum well sample

Temperature-dependent picosecond non-degenerate four-wave-mixing experiments were performed to explore the carrier dynamics in an InGaN/GaN multiple quantum well sample, in which light emission enhancement with surface plasmon (SP) coupling has been identified. In the time-resolved photoluminescence results, we can identify the faster carrier decay time of the sample with surface plasmon coupling. The faster decay time is due to this sample's ability to create additional channels for effective carrier recombination. In the four-wave-mixing results, a slower grating decay time of the sample with surface plasmon coupling was measured. The diffusion coefficients and surface recombination velocities of photo-created carriers were estimated by modeling the decay rate of transient grating signals. For the sample for which surface plasmon coupling exists, smaller diffusion coefficients and slower surface recombination velocities can be estimated when the temperatures are above 150 K. The carriers coupling with some SP modes is not the only mechanism contributing to emission enhancement. In the InGaN/GaN multiple quantum well sample, surface recombination suppressed by SP coupling is another factor for increased light emission efficiency.

Bayesian Inference and Portfolio Efficiency

A Bayesian approach is used to investigate a sample's information about a portfolio's degree of inefficiency. With standard diffuse priors, posterior distributions for measures of portfolio inefficiency can concentrate well away from values consistent with efficiency, even when the portfolio is exactly efficient in the sample. The data indicate that the NYSE-AMEX market portfolio is rather inefficient in the presence of a riskless asset, although this conclusion is justified only after an analysis using informative priors. Including a riskless asset significantly reduces any sample's ability to produce posterior distributions supporting small degrees of inefficiency.