Label-free molecular detection of antibiotic susceptibility for Mycobacterium smegmatis using a low cost electrode format.

Today, the emergence of antibiotic resistance in pathogenic bacteria is considered an important problem for society. Excessive consumption of antibiotics, long-term treatments, and inappropriate prescriptions continually increase the severity of the problem. Improving antibiotic stewardship requires improved diagnostic testing, and, therefore, in vitro antibiotic susceptibility testing is becoming increasingly important. This research details the development of an antibiotic susceptibility test for Mycobacterium smegmatis using streptomycin as antibiotics. This strain was selected because it is a member of the slow growing Mycobacterium genus and serves as a useful surrogate organism for M. tuberculosis. A commercially available and low-cost screen-printed gold electrode in combination with a specifically developed nucleic acid probe sequence for the 16SrRNA region of the mycobacterial genome was employed to monitor M. smegmatis nucleic acid sequences using the techniques of square-wave voltammetry and electrochemical impedance spectroscopy. The results show that it was possible to detect M. smegmatis sequences and distinguish antibiotic-treated cells from untreated cells with a label-free molecular detection. As a result, the in vitro antibiotic susceptibility test revealed that M. smegmatis showed sensitivity to streptomycin after a 24-H incubation, with the developed protocol representing a potential approach to determining antibiotic susceptibility more quickly and economically than current methods.

A facile and cost-effective TEM grid approach to design gold nano-structured substrates for high throughput plasmonic sensitive detection of biomolecules.

A commercial TEM grid was used as a mask for the creation of extremely well-organized gold micro-/nano-structures on a glass substrate via a high temperature annealing process at 500 °C. The structured substrate was (bio)functionalized and used for the high throughput LSPR immunosensing of different concentrations of a model protein named bovine serum albumin.

In vivo observation of gold nanoparticles in the central nervous system of Blaberus discoidalis.

BACKGROUND: Nanoparticles (NPs) are widely studied for biomedical applications. Understanding interactions between NPs and biomolecules or cells has yet to be achieved. Here we present a novel in vivo method to study interactions between NPs and the nervous system of the discoid or false dead-head roach, Blaberus discoidalis. The aims of this study were to present a new and effective method to observe NPs in vivo that opens the door to new methods of study to observe the interactions between NPs and biological systems and to present an inexpensive and easy-to-handle biological system. RESULTS: Negatively charged gold nanoparticles (nAuNPs) of 50 nm in diameter were injected into the central nervous system (CNS) of the insect. By using such a cost effective method, we were able to characterize nAuNPs and to analyze their interactions with a biological system. It showed that the charged particles affected the insect's locomotion. The nAuNPs affected the insect's behavior but had no major impacts on the life expectancy of the cockroach after two months of observation. This was apparently due to the encapsulation of nAuNPs inside the insect's brain. Based on cockroach's daily activity, we believed that the encapsulation occurred in the first 17 days. CONCLUSIONS: The method proposed here is an inexpensive and reliable way of observing the response of biological systems to nanoparticles in-vivo. It opens new windows to further understand how nanoparticles affect neural communication by monitoring insect activity and locomotion.

Four-thousand-year-old gold artifacts from the Lake Titicaca basin, southern Peru.

Artifacts of cold-hammered native gold have been discovered in a secure and undisturbed Terminal Archaic burial context at Jiskairumoko, a multicomponent Late Archaic-Early Formative period site in the southwestern Lake Titicaca basin, Peru. The burial dates to 3776 to 3690 carbon-14 years before the present (2155 to 1936 calendar years B.C.), making this the earliest worked gold recovered to date not only from the Andes, but from the Americas as well. This discovery lends support to the hypothesis that the earliest metalworking in the Andes was experimentation with native gold. The presence of gold in a society of low-level food producers undergoing social and economic transformations coincident with the onset of sedentary life is an indicator of possible early social inequality and aggrandizing behavior and further shows that hereditary elites and a societal capacity to create significant agricultural surpluses are not requisite for the emergence of metalworking traditions.

Dynamic sentiment spillovers among crude oil, gold, and Bitcoin markets: Evidence from time and frequency domain analyses.

This paper examines the sentiment spillovers among oil, gold, and Bitcoin markets by employing spillovers index methods in a time-frequency framework. We find that the total sentiment spillover among crude oil, gold and Bitcoin markets is time-varying and is greatly affected by major market events. The directional sentiment spillovers are also time-varying. On average, the Bitcoin market is the major transmitter of directional sentiment spillovers, whereas the crude oil and gold markets are the major receivers. In particular, the sentiment spillover effects are major created at high-frequency components, implying that the markets rapidly process the sentiment spillover effects and the shock is transmitted over the short-term. Moreover, we also find that the sentiment spillover effects differ significantly in term of intensity and direction when compared with return and volatility spillover effects. The present study has certain applications for investors and policymakers.

Causes and consequences of a tropical forest gold rush in the Guiana Shield, South America.

Statistical and spatial analyses of both historical time series and remotely sensed data show a link between the spatial distribution and growth of gold production across the Guiana Shield in northeast Amazonia. Results indicate that an exponential rise in production across an expanding area is primarily a delayed response to the 1971-1978 market flotation of international gold prices. The subsequent 10-fold (2-fold) average nominal (real) price increase has provided a compelling economic incentive to mass exploitation of lower-grade gold deposits. The ground-based and remotely sensed distributions of mining activity are strongly attached to these deposits that dominate the region's gold geology. The presence of these gold-bearing formations in conservation and sustainable timber zones has sparked social conflict and environmental degradation across the region. Left unmanaged, more than a quarter-million square-kilometer area of tropical forest zoned for protection and sustainable management could ultimately be compromised by the price-driven boom in gold mining through poorly integrated resource use planning, lack of reclamation effort, and control of illegal operations. Serious public health issues propagated through the unregulated mining environment further erode the financial benefits achieved through gold extraction. This study demonstrates in part how international economic policies successfully stabilizing more conspicuous centers of the global economy can have unintended but profound environmental and social impacts on remote commodity frontiers.

Stylized facts of intraday precious metals.

This paper examines the stylized facts, correlation and interaction between volatility and returns at the 5-minute frequency for gold, silver, platinum and palladium from May 2000 to April 2015. We study the full sample period, as well as three subsamples to determine how high-frequency data of precious metals have developed over time. We find that over the full sample, the number of trades has increased substantially over time for each precious metal, while the bid-ask spread has narrowed over time, indicating an increase in liquidity and price efficiency. We also find strong evidence of periodicity in returns, volatility, volume and bid-ask spread. Returns and volume both experience strong intraday periodicity linked to the opening and closing of major markets around the world while the bid-ask spread is at its lowest when European markets are open. We also show a bilateral Granger causality between returns and volatility of each precious metal, which holds for the vast majority subsamples.

A Self-Assembled, Low-Cost, Microstructured Layer for Extremely Stretchable Gold Films.

We demonstrate a simple, low-cost, and green approach to deposit a microstructured coating on the silicone elastomer polydimethylsiloxane (PDMS) that can be coated with gold to produce highly stretchable and conductive films. The microstructured coating is fabricated using an aqueous emulsion of poly(vinyl acetate) (PVAc): common, commercially available white glue. The aqueous glue emulsion self-assembles on the PDMS surface to generate clustered PVAc globules, which can be conformally coated with gold. The microstructured surface provides numerous defect sites that localize strain when the structure is stretched, resulting in the initiation of numerous microcracks. As the structure is further elongated, the microcracks interact with one another, preventing long-range crack propagation and thus preserving the conduction pathway. The resistance of PDMS/glue/gold structures remains remarkably low (23 times the initial resistance) up to 65% elongation, making these structure useful as stretchable interconnects. Decreasing the concentration of the PVAc aqueous emulsion reduces the density of defect sites of the microstructure, which increases the change in resistance of the gold films with stretching. In this way, we can tune the resistance changes of the PDMS/glue/gold structures and increase their sensitivity to strain. We demonstrate the use of these structures as wearable, soft strain sensors.

Nazi Dental Gold: from Dead Bodies to Swiss Banks.

On the 23rd of September 1940 SS Reichsfürher Heinrich Himmler, gave the SS doctors orders to collect the gold teeth from the mouths of those killed in death camps. Here we ask: who were the SS dentists who are directly implicated in that collection, what were the figures behind the process and how did the Nazis conduct this retrieval of gold? Here we give the answers for the first time...

Cost evaluation of novel therapeutics in rheumatoid arthritis (CENTRA): a decision analysis model.

This study was performed to evaluate the potential costs of a hypothetical novel biological agent (BIO) as a therapy for rheumatoid arthritis (RA), compared with oral methotrexate (MTX) and intramuscular gold (IMG). A decision analysis model was used to compare the total costs of treating a cohort of 10,000 RA patients with each agent for 6 months. Total costs included direct costs and indirect costs. Baseline estimates were subjected to sensitivity analysis. Total costs per person were: MTX, $5,430; IMG, $6,725; BIO, $9,411. In sensitivity analysis, the primary cost drivers for MTX and IMG were the indirect costs of RA and monitoring costs. In contrast, total costs of the BIO were driven predominantly by medication costs. Sensitivity analysis showed, even when efficacy and safety were optimized, costs for the BIO still substantially exceeded those of MTX and IMG. Medication costs will be an important consideration in the development of novel BIOs for RA.

[Association between reported annual gold mining extraction and incidence of malaria in Mato Grosso-Brazil, 1985-1996]. / Associação entre a produção anual de ouro em garimpos e incidência de malária em Mato Grosso - Brasil, 1985-1996.

A secondary data analysis was performed using an ecological design to study the association between malaria incidence rates, the reported annual production of gold mining extraction and monetary investments for the control of malaria from 1985 to 1996 in Mato Grosso, Brazil. A positive and statistically significant (p<0.001) association between the amount of gold extracted and MIR was obtained in multivariate regression analysis, even after allowing for financial investments in malaria control activities. This finding contributes to an understanding of the decrease observed in malaria incidence in Mato Grosso during the last decade, in view of the significant decrease in gold mining within the region during this period.