pure gold
Recently Published Documents


TOTAL DOCUMENTS

252
(FIVE YEARS 47)

H-INDEX

24
(FIVE YEARS 2)

Biosensors ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 21
Author(s):  
Pawel Falkowski ◽  
Piotr Mrozek ◽  
Piotr Miluski ◽  
Zenon Lukaszewski ◽  
Ewa Gorodkiewicz

Non-fluidic array SPR imaging (SPRi) with appropriate biosensors is a new tool for the determination of various biomarkers in body fluids. Numerous biomarkers can be determined without signal enhancement or preliminarily preconcentration. The introduction of a new material solution of the chip may increase the scope of the application of this technique. Solutions with adhesive separating foil and an Ag/Au chip were compared with the previously used two-paint separating polymer and pure gold chip. These solutions were tested using the example of a biosensor for cathepsin D (Cath D), which consisted of pepstatin A (a Cath D inhibitor) immobilized via a cysteamine linker using the NHS/EDC protocol. Four material versions of the Cath D biosensor proved adequate in terms of range of linearity, LOQ, precision and recovery. All four versions of the biosensor were used for the determination of Cath D in the blood serum patients with glioblastoma and control samples, producing very similar results and showing an elevated biomarker concentration in the case of cancer. Therefore, the problem of determining the correct level of Cath D in the serum of healthy individuals has been resolved, correcting literature data which ranged over three orders of magnitude.


Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1442
Author(s):  
Heike Lisa Kerstin Stephanie Stolle ◽  
Jonas Jakobus Kluitmann ◽  
Andrea Csáki ◽  
Johann Michael Köhler ◽  
Wolfgang Fritzsche

In this study the catalytic activity of different gold and bimetallic nanoparticle solutions towards the reduction of methylene blue by sodium borohydride as a model reaction is investigated. By utilizing differently shaped gold nanoparticles, i.e., spheres, cubes, prisms and rods as well as bimetallic gold–palladium and gold–platinum core-shell nanorods, we evaluate the effect of the catalyst surface area as available gold surface area, the shape of the nanoparticles and the impact of added secondary metals in case of bimetallic nanorods. We track the reaction by UV/Vis measurements in the range of 190–850 nm every 60 s. It is assumed that the gold nanoparticles do not only act as a unit transferring electrons from sodium borohydride towards methylene blue but can promote the electron transfer upon plasmonic excitation. By testing different particle shapes, we could indeed demonstrate an effect of the particle shape by excluding the impact of surface area and/or surface ligands. All nanoparticle solutions showed a higher methylene blue turnover than their reference, whereby gold nanoprisms exhibited 100% turnover as no further methylene blue absorption peak was detected. The reaction rate constant k was also determined and revealed overall quicker reactions when gold or bimetallic nanoparticles were added as a catalyst, and again these were highest for nanoprisms. Furthermore, when comparing gold and bimetallic nanorods, it could be shown that through the addition of the catalytically active second metal platinum or palladium, the dye turnover was accelerated and degradation rate constants were higher compared to those of pure gold nanorods. The results explore the catalytic activity of nanoparticles, and assist in exploring further catalytic applications.


2021 ◽  
Vol 37 (5) ◽  
pp. 525-535
Author(s):  
Jang-Jon Lee ◽  
Boyeon An ◽  
Kiok Han ◽  
Ryangmi Lee ◽  
Ji Hyun Yoo ◽  
...  

This study identified material properties through scientific analysis on Jikgeumdan(satin with gold threads) from Donggungbi-Wonsam and the gold threads used in the embroidery. The Donggungbi-Wonsam’s base of gold threads were estimated to have used mulberry fiber’s Korean paper(Hanji) because non-wood-based fibers were observed. The X-ray spectrometer showed that the Tongsuseulan of Donggungbi-Wonsam was a flat gold thread of pure gold and Jikgeumdan of flat silver thread of its Saekdong and Hansam. High sulfur levels were detected in the flat silver thread, which appeared to have formed silver sulfide by either manufacturing process using sulfur or conservation environment. he dragon insignia’s embroidery is also described as two types twisted gold threads; pure gold and alloying-gold and silver. while dragon insignia’s border line is decorated with a twisted gold thread of pure gold. In particular, it was investigated that adhesives such as an animal glue, a protein-based compound by gas chromatography mass spectrometry. Additionally, XRF and Raman spectroscopy analysis on the mixture substances between the metal surface and the base paper of gold threads identified talc and quartz in the gold threads and Seokganju(hematite) in the flat silver threads.


2021 ◽  
Vol 4 (2) ◽  
pp. 56
Author(s):  
Migena Ceyhan ◽  
Zeynep Orhan ◽  
Dimitrios Karras

Web 2.0 has given to all people the right to become a representative of a huge cast of informal media. The importance of this power is getting more evident everyday. Every social media actor can influence the rest of the world by one’s own opinions, feelings, and thoughts generously shared on multiple media. This information belonging to various fields of life can be very handy and be used to one’s advantage, gaining precious experience. One of the greatest problems that this poses is the huge number of data spread everywhere, which are difficult to process as row data per se. Social media and general sentiment text analysis is of much valuable use, accomplishing the task extracting pure gold out of raw mineral. The key point of this investigation is to characterize new reviews automatically. To start with, features selected out of all the word roots appearing in the comments were used to train the system according to known machine learning algorithms. Next, critical words determining positive or negative sense were extracted. Another strategy was attempted eliminating common terms and dealing only with the significant class-determining words to build vocabulary with them. Aparts from linear approach, vector based feature sets were prepared out all or some of the features. The outcomes acquired were analyzed and compared leading to important conclusions, emphasizing the importance of feature selection in text classification.


Biosensors ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 298
Author(s):  
Pawel Falkowski ◽  
Piotr Mrozek ◽  
Zenon Lukaszewski ◽  
Lukasz Oldak ◽  
Ewa Gorodkiewicz

The array SPR imaging (SPRi) technique is well suited to the determination of biomarkers in body fluids, called liquid biopsy. No signal enhancement or analyte preconcentration is required. With the aim of achieving signal enhancement and lowering the cost of a single determination, the replacement of gold-covered chips by silver–gold chips was investigated. The aim of this work was to investigate the analytical characteristics of a biosensor formed on a Ag/Au chip and to compare them with those of a biosensor formed on a gold chip. A biosensor for the determination of cathepsin S (Cath S) was chosen as an example. The biosensor consisted of the linker cysteamine and an immobilized rat monoclonal antibody specific for cathepsin S. Both biosensors exhibited a Langmuirian response to Cath S concentration, with linear response ranging from LOQ to 1.5 ng mL−1. The LOQ is 0.1 ng mL−1 for the biosensor formed on the Ag/Au chip, and 0.22 ng mL−1 for that formed on the gold chip. Recoveries and precision for medium and high Cath S concentrations were acceptable for both biosensors, i.e., precision better than 10% and recoveries within the range 102–105%. However, the results for the lowest Cath S concentration were better for the biosensor formed on the Ag/Au chip (9.4 and 106% for precision and recovery, respectively). Generally, no significant differences in analytical characteristics were observed between the Ag/Au and Au chips. The two biosensors were also compared in the determination of Cath S in real samples. Nine plasma samples from healthy donors and nine from patients with ovarian cancer were analyzed for Cath S concentration with the biosensors formed on Ag/Au and Au chips. The results obtained with the two biosensors were very similar and show no significant differences on the Bland–Altman plot. The Cath S concentration in the blood plasma of ovarian cancer patients was elevated by one order of magnitude as compared with the control (12.6 ± 3.6 vs. 1.6 ± 1.2 ng mL−1).


2021 ◽  
Vol 23 (2) ◽  
pp. 247-256
Author(s):  
Muhammad Nur ◽  
Muhammad Salda ◽  
Hamdani Hamdani

A country must protect its citizens, including the rape victims. Unfortunately, the protection is not clearly regulated in the form of restitution and compensation in the Criminal Code (KUHP) and Law Procedures Code (KUHAP). The issuance of Qanun Number 6 the Year 2014 about Jinayah Law has contributed significant changes and progress to the protection of rape victims. The study focused on how the politics of criminal law protects rape victims based on the Qanun of Jinayah law in Aceh. The research applied the normative juridical method, specifically analytical descriptive research. The data sources were primary and secondary legal sources. The data analysis was conducted qualitatively. The result indicated that there are two types of protection in the politics of criminal law on the protection of rape victims based on the qanun of jinayah law. First, the ta'zir penalty or fines in the form of gold to the perpetrators. Second, the payment of uqubat restitution from the perpetrators to the rape victims, a maximum of 750 grams of pure gold.


2021 ◽  
Vol 13 (9) ◽  
Author(s):  
Daniel Berger ◽  
Michael Brauns ◽  
Gerhard Brügmann ◽  
Ernst Pernicka ◽  
Nicole Lockhoff

AbstractGold parting enabled the production of very pure gold for various purposes from the sixth century BC onwards, but analytical proof of this pyrotechnical process is difficult. We describe a new analytical approach for the identification of purified gold combining silver and copper isotopic with trace element analyses. Parting experiments were performed with gold-silver-copper alloys using the classical salt cementation process to investigate potential silver and copper isotope fractionation and changes in trace element concentrations. In addition, we provide the first comprehensive dataset of silver isotope ratios of archaeological gold objects from the Mediterranean and Central Europe to test whether or not gold refining can be identified on the basis of isotope systematics. The results show that very heavy silver and copper isotopic compositions are clear evidence for parted gold, but that the application of copper isotopes might be limited.


Sign in / Sign up

Export Citation Format

Share Document