Low household income increases the risk of tuberculosis recurrence: a retrospective nationwide cohort study in South Korea

OBJECTIVES

We assessed the impact of household income on tuberculosis (TB) recurrence and the long-term impact of TB on household income.

STUDY DESIGN

This was a retrospective nationwide cohort study of patients with drug-susceptible TB (DS-TB) and TB recurrence.

METHODS

Using the South Korean national TB cohort database, we identified a sub-set cohort of patients with newly diagnosed drug-susceptible TB between 2013 and 2016 and tracked their TB recurrence and longitudinal income data from 2007 to 2018. Income levels were evaluated as 'Medical aid' and quintile categories. To assess risk factors associated with TB recurrence, we used a sub-distribution hazard model, adjusting for the competing risks of death.

RESULTS

Of 66,690 patients successfully treated with DS-TB, 2095 (3.1 %) experienced recurrence during a median follow-up of 39 months. The incidence of TB recurrence was 982.1/100,000 person-years, with 50.3 % of the recurrences occurring within 1 year of treatment completion. The risk of TB recurrence increased with decreasing income levels, with the highest risk observed in the lowest income group. The effect of income on TB recurrence was prominent in males but not in females. Overall, patients with TB recurrence experienced a linear decline in income levels, compared with those without recurrence.

CONCLUSIONS

Household income during the initial TB episode was an important risk factor for TB recurrence, particularly in males.

To Test or Not? Xpert MTB/RIF as an Alternative to Smear Microscopy to Guide Line Probe Assay Testing for Drug-Resistant Tuberculosis

Xpert MTB/RIF (Xpert) revolutionized tuberculosis (TB) diagnosis. Laboratory decision making on whether widely-used reflex drug susceptibility assays (MTBDRplus, first-line resistance; MTBDRsl, second-line) are conducted is based on smear status, with smear-negative specimens often excluded. We performed receiver operator characteristic (ROC) curve analyses using bacterial load information (smear microscopy grade, Xpert-generated semi-quantitation categories and minimum cycle threshold [CTmin] values) from Xpert rifampicin-resistant sputum for the prediction of downstream line probe assay results as "likely non-actionable" (no resistance or susceptible results generated). We evaluated actionable-to-non-actionable result ratios and pay-offs with missed resistance versus LPAs done universally. Smear-negatives were more likely than smear-positive specimens to generate a non-actionable MTBDRplus (23% [133/559] versus 4% [15/381]) or MTBDRsl (39% [220/559] versus 12% [47/381]) result. However, excluding smear-negatives would result in missed rapid diagnoses (e.g., only 49% [264/537] of LPA-diagnosable isoniazid resistance would be detected if smear-negatives were omitted). Testing smear-negatives with a semi-quantitation category ≥ "medium" had a high ratio of actionable-to-non-actionable results (12.8 or a 4-fold improvement versus testing all using MTBDRplus, 4.5 or 3-fold improvement for MTBDRsl), which would still capture 64% (168/264) and 77% (34/44) of LPA-detectable smear-negative resistance, respectively. Use of CTmins permitted optimization of this ratio with higher specificity for non-actionable results but decreased resistance detected. Xpert quantitative information permits identification of a smear-negative subset in whom the payoffs of the ratio of actionable-to-non-actionable LPA results with missed resistance may prove acceptable to laboratories, depending on context. Our findings permit the rational expansion of direct DST to certain smear-negative sputum specimens.

Understanding patient-level costs of weekly isoniazid-rifapentine (3HP) among people living with HIV in Uganda

BACKGROUND: Twelve weeks of weekly isoniazid and rifapentine (3HP) prevents TB disease among people with HIV (PWH), but the costs to people of taking TB preventive treatment is not well described.METHODS: We surveyed PWH who initiated 3HP at a large urban HIV/AIDS clinic in Kampala, Uganda, as part of a larger trial. We estimated the cost of one 3HP visit from the patient perspective, including both out-of-pocket costs and estimated lost wages. Costs were reported in 2021 Ugandan shillings (UGX) and US dollars (USD; USD1 = UGX3,587)RESULTS: The survey included 1,655 PWH. The median participant cost of one clinic visit was UGX19,200 (USD5.36), or 38.5% of the median weekly income. Per visit, the cost of transportation was the largest component (median: UGX10,000/USD2.79), followed by lost income (median: UGX4,200/USD1.16) and food (median: UGX2,000/USD0.56). Men reported greater income loss than women (median: UGX6,400/USD1.79 vs. UGX3,300/USD0.93), and participants who lived further than a 30-minute drive to the clinic had higher transportation costs than others (median: UGX14,000/USD3.90 vs. UGX8,000/USD2.23).CONCLUSION: Patient-level costs to receive 3HP accounted for over one-third of weekly income. Patient-centered approaches to averting or defraying these costs are needed.

Fabrication of Rapid Electrical Pulse-Based Biosensor Consisting of Truncated DNA Aptamer for Zika Virus Envelope Protein Detection in Clinical Samples

Zika virus (ZV) infection causes fatal hemorrhagic fever. Most patients are unaware of their symptoms; therefore, a rapid diagnostic tool is required to detect ZV infection. To solve this problem, we developed a rapid electrical biosensor composed of a truncated DNA aptamer immobilized on an interdigitated gold micro-gap electrode and alternating current electrothermal flow (ACEF) technique. The truncated ZV aptamer (T-ZV apt) was prepared to reduce the manufacturing cost for biosensor fabrication, and it showed binding affinity similar to that of the original ZV aptamer. This pulse-voltammetry-based biosensor was composed of a T-ZV apt immobilized on an interdigitated micro-gap electrode. Atomic force microscopy was used to confirm the biosensor fabrication. In addition, the optimal biosensor performance conditions were investigated using pulse voltammetry. ACEF promoted aptamer-target binding, and the target virus envelope protein was detected in the diluted serum within 10 min. The biosensor waveform increased linearly as the concentration of the Zika envelope in the serum increased, and the detection limit was 90.1 pM. Our results suggest that the fabricated biosensor is a significant milestone for rapid virus detection.

Cost to perform door-to-door universal sputum screening for TB in a high-burden community

BACKGROUND: Population-based active case-finding (ACF) identifies people with TB in communities but can be costly.METHODS: We conducted an empiric costing study within a door-to-door household ACF campaign in an urban community in Uganda, where all adults, regardless of symptoms, were screened by sputum Xpert Ultra testing. We used a combination of direct observation and self-reported logs to estimate staffing requirements. Study budgets were reviewed to collect costs of overheads, equipment, and consumables. Our primary outcome was the cost per person diagnosed with TB.RESULTS: Over a 28-week period, three teams of two people collected sputum from 11,341 adults, of whom 48 (0.4%) tested positive for TB. Screening 1,000 adults required 258 person-hours of effort at a cost of US$402,000, 70% of which was for GeneXpert cartridges. The estimated cost per person screened was $36 (95% uncertainty range [95% UR] 34-38), and the cost per person diagnosed with Xpert-positive TB was $8,400 (95% UR 8,000-8,900). The prevalence of TB in the underlying community was the primary modifiable determinant of the cost per person diagnosed.CONCLUSION: Door-to-door screening can be feasibly performed at scale, but will require effective triage and identification of high-prevalence populations to be affordable and cost-effective.

Surface of CuO Nanoparticles Modified by p-Benzoquinone for N2-Selective Membrane

In this study, CuO nanoparticles and p-benzoquinone (p-BQ) were added to a polyvinylpyrrolidone (PVP) matrix to increase N₂/CO₂ selectivity. The added p-BQ allowed CuO to be distributed in a uniform size in the PVP/CuO composite membrane and the matrix to be flexible by forming the interaction with PVP. The surface modification of CuO by p-BQ and the well-dispersed size affected the increase in the separation performance. The PVP/CuO/p-BQ composite membranes showed an N₂/CO₂ selectivity of about 23.1 with N₂ permeance of about 13.3 GPU, while the separation performance of PVP was not observed. The enhanced separation performance is attributable to the surface of CuO nanoparticles modified by p-BQ inducing CO₂ molecules to be relatively slowly transported by the adsorption properties in the polymer matrix. The chemical properties and coordinative interaction for PVP/CuO/p-BQ composite membrane were measured by FT-IR spectroscopy, thermogravimetric analysis, UV-vis, scanning electron microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy.

NaCl Ionization-Based Moisture Sensor Prepared by Aerosol Deposition for Monitoring Respiratory Patterns

A highly polarizable moisture sensor with multimodal sensing capabilities has great advantages for healthcare applications such as human respiration monitoring. We introduce an ionically polarizable moisture sensor based on NaCl/BaTiO₃ composite films fabricated using a facile aerosol deposition (AD) process. The proposed sensing model operates based on an enormous NaCl ionization effect in addition to natural moisture polarization, whereas all previous sensors are based only on the latter. We obtained an optimal sensing performance in a 0.5 µm-thick layer containing NaCl-37.5 wt% by manipulating the sensing layer thickness and weight fraction of NaCl. The NaCl/BaTiO₃ sensing layer exhibits outstanding sensitivity over a wide humidity range and a fast response/recovery time of 2/2 s; these results were obtained by performing the one-step AD process at room temperature without using any auxiliary methods. Further, we present a human respiration monitoring system using a sensing device that provides favorable and stable electrical signals under diverse respiratory scenarios.

Effects of Mg, Ca, Sr, and Ba Dopants on the Performance of La2O3 Catalysts for the Oxidative Coupling of Methane

Oxidative coupling of methane (OCM) is a reaction to directly convert methane into high value-added hydrocarbons (C₂₊) such as ethylene and ethane using molecular oxygen and a catalyst. This work investigated lanthanum oxide catalysts for OCM, which were promoted with alkaline-earth metal oxides (Mg, Ca, Sr, and Ba) and prepared by the solution-mixing method. The synthesized catalysts were characterized using X-ray powder diffraction, CO₂-programmed desorption, and X-ray photoelectron spectroscopy. The comparative performance of each promoter showed that promising lanthanum-loaded alkaline-earth metal oxide catalysts were La-Sr and La-Ba. In contrast, the combination of La with Ca or Mg did not lead to a clear improvement of C₂₊ yield. The most promising LaSr50 catalyst exhibited the highest C₂₊ yield of 17.2%, with a 56.0% C₂₊ selectivity and a 30.9% CH₄ conversion. Catalyst characterization indicated that their activity was strongly associated with moderate basic sites and surface-adsorbed oxygen species of O₂ ^-. Moreover, the catalyst was stable over 25 h at a reactor temperature of 700 °C.

Fabrication of an electrochemical biosensor composed of multi-functional Ag ion intercalated DNA four-way junctions/rhodium nanoplate heterolayer on a micro-gap for C-reactive protein detection in human serum

As inflammation plays a role in the pathogenesis of acute coronary syndromes, C-reactive protein (CRP) can be used as a biomarker. To detect CRP precisely, the authors prepared a CRP electrochemical biosensor consisting of an eight Ag ion-intercalated multifunctional DNA four-way junction (MF-DNA-4WJ) and a porous rhodium nanoparticle (pRhNP) heterolayer on a micro-gap electrode. To increase conductivity, we used eight Ag⁺ ion-inserted DNA four-way junctions through a C-C mismatch. Each DNA 4WJ was designed to have the CRP aptamer sequence, an anchoring region (thiol group), and two of four C-C mismatch regions at the end of the fragments. After an annealing step, the MF-DNA-4WJ assembly configuration and selective binding of CRP were confirmed through native TBM-PAGE (Tris-borate-magnesium chloride-polyacrylamide gel electrophoresis). The Au micro-gap electrode was fabricated to load 5 μl of the sample, and this was performed during eight experiments on one chip to establish the accuracy of the data. Then, pRhNPs were immobilized on a Au micro-gap electrode using cysteamine. To confirm the electrochemical properties, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted. The durability of pRhNPs was confirmed through CV. To test the sensing performance of the prepared CRP biosensor, the limit of detection (LOD) and selectivity tests were conducted using EIS. The results indicated that charge transfer resistance (R_ct) can be used efficiently to probe these interactions within the variable CRP concentration range, from 1 pM to 100 nM (0.23 ng L^-1-23 μg L^-1). The LOD of this sensor was 0.349 pM (0.08 ng L^-1) (at S/N = 3). As a result of diluting the CRP to the same concentration range in a 20% human serum sample, the LOD was 3.55 fM (0.814 pg L^-1) (at S/N = 3).

Silver Nanowire Network Hybridized with Silver Nanoparticle-Anchored Ruthenium Oxide Nanosheets for Foldable Transparent Conductive Electrodes

Facile strategies in flexible transparent conductive electrode materials that can sustain their electrical conductivities under 1 mm-scale radius of curvature are required for wider applications such as foldable devices. We propose a rational design as well as a fabrication process for a silver nanowire-based transparent conductive electrode with low sheet resistance and high transmittance even after prolonged cyclic bending. The electrode is fabricated on a poly(ethylene terephthalate) film through the hybridization of silver nanowires with silver nanoparticles-anchored RuO₂ nanosheets. This hybridization significantly improves the performance of the silver nanowire network under severe bending strain and creates an electrically percolative structure between silver nanowires and RuO₂ nanosheets in the presence of anchored silver nanoparticles on the surface of RuO₂ nanosheets. The resistance change of this hybrid transparent conductive electrode is 8.8% after 200,000 bending cycles at a curvature radius of 1 mm, making it feasible for use in foldable devices.

Determining the value of TB active case-finding: current evidence and methodological considerations

Active case-finding (ACF) is an important component of the End TB Strategy. However, ACF is resource-intensive, and the economics of ACF are not well-understood. Data on the costs of ACF are limited, with little consistency in the units and methods used to estimate and report costs. Mathematical models to forecast the long-term effects of ACF require empirical measurements of the yield, timing and costs of case detection. Pragmatic trials offer an opportunity to assess the cost-effectiveness of ACF interventions within a 'real-world´ context. However, such analyses generally require early introduction of economic evaluations to enable prospective data collection on resource requirements. Closing the global case-detection gap will require substantial additional resources, including continued investment in innovative technologies. Research is essential to the optimal implementation, cost-effectiveness, and affordability of ACF in high-burden settings. To assess the value of ACF, we must prioritize the collection of high-quality data regarding costs and effectiveness, and link those data to analytical models that are adapted to local settings.

Fabrication of Electrochemical Influenza Virus (H1N1) Biosensor Composed of Multifunctional DNA Four-Way Junction and Molybdenum Disulfide Hybrid Material

The outbreak of the influenza virus (H1N1) has symptoms such as coughing, fever, and a sore throat, and due to its high contagious power, it is fatal to humans. To detect H1N1 precisely, the present study proposed an electrochemical biosensor composed of a multifunctional DNA four-way junction (4WJ) and carboxyl molybdenum disulfide (carboxyl-MoS2) hybrid material. The DNA 4WJ was constructed to have the hemagglutinin aptamer on the head group (recognition part); each of the two arms has four silver ions (signal amplification part), and the tail group has an amine group (anchor). This fabricated multifunctional DNA 4WJ can specifically and selectively bind to hemagglutinin. Moreover, the carboxyl-MoS2 provides an increase in the sensitivity of this biosensor. Carboxyl-MoS2 was immobilized using a linker on the electrode, followed by the immobilization of the multifunctional 4WJ on the electrode. The synthesis of carboxyl-MoS2 was confirmed by field emission scanning electron microscopy (FE-SEM), and the surface of the electrode was confirmed by atomic force microscopy. When H1N1 was placed in the immobilized electrode, the presence of H1N1 was confirmed by electrochemical analysis (cyclic voltammetry, electrochemical impedance spectroscopy). Through selectivity tests, it was also possible to determine whether this sensor responds specifically and selectively to H1N1. We confirmed that the biosensor showed a linear response to H1N1, and that H1N1 could be detected from 100 nM to 10 pM. Finally, clinical tests, in which hemagglutinin was diluted with human serum, showed a similar tendency to those diluted with water. This study showed that the multi-functional DNA 4WJ and carboxyl-MoS2 hybrid material can be applied to a electrochemical H1N1 biosensor.

Ultrasonic assisted exfoliation for efficient production of RuO2 monolayer nanosheets

RuO2 monolayer nanosheets can be easily synthesized by an ultrasonic assisted exfoliation process.

Recent Development of Aptasensor for Influenza Virus Detection

In nowadays, we have entered the new era of pandemics and the significance of virus detection deeply impacts human society. Viruses with genetic mutations are reported nearly every year, and people have prepared tools to detect the virus and vaccines to ensure proper treatments. Influenza virus (IV) is one of the most harmful viruses reporting various mutations, sub-types, and rapid infection speed for humans and animals including swine and poultry. Moreover, IV infection presents several harmful symptoms including cough, fever, diarrhea, chills, even causing death. To reduce the IV-induced harm, its proper and rapid detection is highly required. Conventional techniques were used against various IV sub-types including H1N1, H3N2, and H5N1. However, some of the techniques are time-consuming, expensive, or labor-intensive for detecting IV. Recently, the nucleic acid-based aptamer has gained attention as a novel bioprobe for constructing a biosensor. In this review, the authors discuss the recent progress in aptasensors for detecting IV in terms of an electrochemical and an optical biosensor.

Recent Advances in Biomolecule-Nanomaterial Heterolayer-Based Charge Storage Devices for Bioelectronic Applications

With the acceleration of the Fourth Industrial Revolution, the development of information and communications technology requires innovative information storage devices and processing devices with low power and ultrahigh stability. Accordingly, bioelectronic devices have gained considerable attention as a promising alternative to silicon-based devices because of their various applications, including human-body-attached devices, biomaterial-based computation systems, and biomaterial-nanomaterial hybrid-based charge storage devices. Nanomaterial-based charge storage devices have witnessed considerable development owing to their similarity to conventional charge storage devices and their ease of applicability. The introduction of a biomaterial-to-nanomaterial-based system using a combination of biomolecules and nanostructures provides outstanding electrochemical, electrical, and optical properties that can be applied to the fabrication of charge storage devices. Here, we describe the recent advances in charge storage devices containing a biomolecule and nanoparticle heterolayer including (1) electrical resistive charge storage devices, (2) electrochemical biomemory devices, (3) field-effect transistors, and (4) biomemristors. Progress in biomolecule-nanomaterial heterolayer-based charge storage devices will lead to unprecedented opportunities for the integration of information and communications technology, biotechnology, and nanotechnology for the Fourth Industrial Revolution.

Synthesis of Value-Added Chemicals via Oxidative Coupling of Methanes over Na2WO4-TiO2-MnO x /SiO2 Catalysts with Alkali or Alkali Earth Oxide Additives

Na₂WO₄-TiO₂-MnO _x /SiO₂ (SM) catalysts with alkali (Li, K, Rb, Cs) or alkali earth (Mg, Ca, Sr, Ba) oxide additives, which were prepared using incipient wetness impregnation, were investigated for oxidative coupling of methane (OCM) to value-added hydrocarbons (C₂₊). A screening test that was performed on the catalysts revealed that SM with Sr (SM-Sr) had the highest yield of C₂₊. X-ray photoelectron spectroscopy analyses indicated that the catalysts with a relatively low binding energy of W 4f_7/2 facilitated a high CH₄ conversion. A combination of crystalline MnTiO₃, Mn₂O₃, α-cristobalite, Na₂WO₄, and TiO₂ phases was identified as an essential component for a remarkable improvement in the activity of the catalysts in the OCM reaction. In attempts to optimize the C₂₊ yield, 0.25 wt % Sr onto SM-Sr achieved the highest C₂₊ yield at 22.9% with a 62.5% C₂₊ selectivity and a 36.6% CH₄ conversion. A stability test of the optimal catalyst showed that after 24 h of testing, its activity decreased by 18.7%.

Novel Hybrid Conductor of Irregularly Patterned Graphene Mesh and Silver Nanowire Networks

We prepared the hybrid conductor of the Ag nanowire (NW) network and irregularly patterned graphene (GP) mesh with enhanced optical transmittance (~98.5%) and mechano-electric stability (ΔR/R_o: ~42.4% at 200,000 (200k) cycles) under 6.7% strain. Irregularly patterned GP meshes were prepared with a bottom-side etching method using chemical etchant (HNO₃). The GP mesh pattern was judiciously and easily tuned by the regulation of treatment time (0–180 min) and concentration (0–20 M) of chemical etchants. As-formed hybrid conductor of Ag NW and GP mesh exhibit enhanced/controllable electrical-optical properties and mechano-electric stabilities; hybrid conductor exhibits enhanced optical transmittance (TT = 98.5%) and improved conductivity (ΔR_s: 22%) compared with that of a conventional hybrid conductor at similar TT. It is also noteworthy that our hybrid conductor shows far superior mechano-electric stability (ΔR/R_o: ~42.4% at 200k cycles; TT: ~98.5%) to that of controls (Ag NW (ΔR/R_o: ~293% at 200k cycles), Ag NW-pristine GP hybrid (ΔR/R_o: ~121% at 200k cycles)) ascribed to our unique hybrid structure.

Resource implications of the latent tuberculosis cascade of care: a time and motion study in five countries

BACKGROUND

The End TB Strategy calls for global scale-up of preventive treatment for latent tuberculosis infection (LTBI), but little information is available about the associated human resource requirements. Our study aimed to quantify the healthcare worker (HCW) time needed to perform the tasks associated with each step along the LTBI cascade of care for household contacts of TB patients.

METHODS

We conducted a time and motion (TAM) study between January 2018 and March 2019, in which consenting HCWs were observed throughout a typical workday. The precise time spent was recorded in pre-specified categories of work activities for each step along the cascade. A linear mixed model was fit to estimate the time at each step.

RESULTS

A total of 173 HCWs in Benin, Canada, Ghana, Indonesia, and Vietnam participated. The greatest amount of time was spent for the medical evaluation (median: 11 min; IQR: 6-16), while the least time was spent on reading a tuberculin skin test (TST) (median: 4 min; IQR: 2-9). The greatest variability was seen in the time spent for each medical evaluation, while TST placement and reading showed the least variability. The total time required to complete all steps along the LTBI cascade, from identification of household contacts (HHC) through to treatment initiation ranged from 1.8 h per index TB patient in Vietnam to 5.2 h in Ghana.

CONCLUSIONS

Our findings suggest that the time requirements are very modest to perform each step in the latent TB cascade of care, but to achieve full identification and management of all household contacts will require additional human resources in many settings.

Silver Nanowire Networks: Mechano-Electric Properties and Applications

With increasing technological demand for portable electronic and photovoltaic devices, it has become critical to ensure the electrical and mechano-electric reliability of electrodes in such devices. However, the limited flexibility and high processing costs of traditional electrodes based on indium tin oxide undermine their application in flexible devices. Among various alternative materials for flexible electrodes, such as metallic/carbon nanowires or meshes, silver nanowire (Ag NW) networks are regarded as promising candidates owing to their excellent electrical, optical, and mechano-electric properties. In this context, there have been tremendous studies on the physico-chemical and mechano-electric properties of Ag NW networks. At the same time, it has been a crucial job to maximize the device performance (or their mechano-electric performance) by reconciliation of various properties. This review discusses the properties and device applications of Ag NW networks under dynamic motion by focusing on notable findings and cases in the recent literature. Initially, we introduce the fabrication (deposition process) of Ag NW network-based electrodes from solution-based coating processes (drop casting, spray coating, spin coating, etc.) to commercial processes (slot-die and roll-to-roll coating). We also discuss the electrical/optical properties of Ag NW networks, which are governed by percolation, and their electrical contacts. Second, the mechano-electric properties of Ag NW networks are reviewed by describing individual and combined properties of NW networks with dynamic motion under cyclic loading. The improved mechano-electric properties of Ag NW network-based flexible electrodes are also discussed by presenting various approaches, including post-treatment and hybridization. Third, various Ag NW-based flexible devices (electronic and optoelectronic devices) are introduced by discussing their operation principles, performance, and challenges. Finally, we offer remarks on the challenges facing the current studies and discuss the direction of research in this field, as well as forthcoming issues to be overcome to achieve integration into commercial devices.

Fabrication of Electrochemical-Based Bioelectronic Device and Biosensor Composed of Biomaterial-Nanomaterial Hybrid

The field of bioelectronics has paved the way for the development of biochips, biomedical devices, biosensors and biocomputation devices. Various biosensors and biomedical devices have been developed to commercialize laboratory products and transform them into industry products in the clinical, pharmaceutical, environmental fields. Recently, the electrochemical bioelectronic devices that mimicked the functionality of living organisms in nature were applied to the use of bioelectronics device and biosensors. In particular, the electrochemical-based bioelectronic devices and biosensors composed of biomolecule-nanoparticle hybrids have been proposed to generate new functionality as alternatives to silicon-based electronic computation devices, such as information storage, process, computations and detection. In this chapter, we described the recent progress of bioelectronic devices and biosensors based on biomaterial-nanomaterial hybrid.

Fabrication of Troponin I Biosensor Composed of Multi-Functional DNA Structure/Au Nanocrystal Using Electrochemical and Localized Surface Plasmon Resonance Dual-Detection Method

In the present study, we fabricated a dual-mode cardiac troponin I (cTnI) biosensor comprised of multi-functional DNA (MF-DNA) on Au nanocrystal (AuNC) using an electrochemical method (EC) and a localized surface plasmon resonance (LSPR) method. To construct a cTnI bioprobe, a DNA 3 way-junction (3WJ) was prepared to introduce multi-functionality. Each DNA 3WJ arm was modified to possess a recognition region (Troponin I detection aptamer), an EC-LSPR signal generation region (methylene blue: MB), and an anchoring region (Thiol group), respectively. After an annealing step, the multi-functional DNA 3WJ was assembled, and its configuration was confirmed by Native-TBM PAGE for subsequent use in biosensor construction. cTnI was also expressed and purified for use in biosensor experiments. To construct an EC-LSPR dual-mode biosensor, AuNCs were prepared on an indium-tin-oxide (ITO) substrate using an electrodeposition method. The prepared multi-functional (MF)-DNA was then immobilized onto AuNCs by covalent bonding. Field emission scanning electron microscope (FE-SEM) and atomic force microscopy (AFM) were used to analyze the surface morphology. LSPR and electrochemical impedance spectroscopy (EIS) experiments were performed to confirm the binding between the target and the bioprobe. The results indicated that cTnI could be effectively detected in the buffer solution and in diluted-human serum. Based on the results of these experiments, the loss on drying (LOD) was determined to be 1.0 pM in HEPES solution and 1.0 pM in 10% diluted human serum. Additionally, the selectivity assay was successfully tested using a number of different proteins. Taken together, the results of our study indicate that the proposed dual-mode biosensor is applicable for use in field-ready cTnI diagnosis systems for emergency situations.

Label-free localized surface plasmon resonance biosensor composed of multi-functional DNA 3 way junction on hollow Au spike-like nanoparticles (HAuSN) for avian influenza virus detection

In the present study, we fabricated a label-free avian influenza (AIV H5N1) detection biosensor composed of a multi-functional DNA 3 way-Junction (3 W J) on a hollow Au spike-like nanoparticle (hAuSN) using a localized surface plasmon resonance (LSPR) method. To construct the multi-functional DNA (MF-DNA) as a bioprobe, the 3 W J was introduced. The proposed AIV detection bioprobe should contain three functionalities: target recognition, signal amplification, and connection to substrate. To achieve this goal, each piece of the DNA 3 W J was tailored to a hemagglutinin (HA) binding aptamer, FAM dye and thiol group, respectively. The assembly of each DNA 3 W J functional fragment was then confirmed by TBM-Native PAGE. Moreover, the hAuSN was immobilized on the indium-tin-oxide (ITO) substrate for LSPR measurement. The DNA 3 W J was immobilized onto the hAuSN electrode through the thiol-group of DNA 3 W J. The fabricated DNA 3 W J/hAuSN heterolayer on the ITO substrate was investigated by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). LSPR experiments were conducted to confirm HA protein binding to the DNA 3 W J/ hAuSN -modified electrode. The proposed biosensor can detected the HA protein in PBS buffer (LOD: 1 pM) as well as in the diluted chicken serum (LOD: 1 pM). The present study details a label-free, simple fabrication method consisted of DNA 3 W J/ hAuSN heterolayer that uses easy-to-tailor elements to detect not only AIV but also various viruses detection platform easily.

Cost-effectiveness of contact screening strategies for tuberculosis among high-school adolescents in South Korea

BACKGROUND

Effective latent tuberculous infection (LTBI) control among adolescents is a critical component of tuberculosis (TB) elimination in Korea.

OBJECTIVE

To compare the cost-effectiveness of the following contact screening strategies for LTBI among high-school adolescents after TB outbreaks: QuantiFERON®-TB Gold In-Tube (QFT-GIT), the tuberculin skin test (TST), or TST/QFT-GIT (two-step strategy).

METHOD

The costs of post-TB outbreak screening strategies were calculated using a mixed (top-down and bottom-up) cost analysis method and expressed in 2015 US dollars. Cost-effectiveness was evaluated using a decision analysis model from the health system perspective, comparing cumulative health care costs and the total number of TB cases averted.

RESULTS

In a hypothetical cohort of 1000 students, screening using the TST-alone strategy averted 1.6 TB cases at a total cost of US$52 566. The QFT-GIT-alone strategy helped avert 2.0 TB cases, but was associated with a much higher total cost (US$108 435), resulting in an incremental cost-effectiveness ratio of US$140 933/TB case averted. The two-step TST/QFT-GIT strategy was worse than the TST-alone strategy, averting 1.3 TB cases at US$75 267.

CONCLUSION

The TST-alone strategy was the most cost-effective; the QFT-GIT-alone strategy averted the greatest number of TB cases but incurred the highest cost in contact investigation for school TB outbreaks.

Costs and operation management of community outreach program for tuberculosis in tribal populations in India

Objective

To evaluate costs of an active case finding (ACF) program with tuberculosis (TB) treatment delivery and monitoring, which targeted a rural tribal population in India.

Method

A time and motion study was conducted to evaluate operations and workload. Costs from the program perspective were assessed using both the bottom-up and top-down costing methods, exclusive of routine TB care costs. The impact of ACF on routine TB laboratory workloads was measured based on the changes in available staff time per smear at nine designated microscopy centers before and after program implementation.

Results

A majority (53.2%) of the community health-care worker's time was spent in traveling to communities, with an average of 22 TB patients (95% CI 19.14-24.94) seen per day per person. Costs (at 2015 $US rates) were US$1.85-US$2.42 per patient screened and submitting sputum, US$2.51-US$4.74 per person diagnosed with TB, and US$22.52-US$34.13 per TB patient completing treatment. Total smear volumes increased significantly after the ACF program, with more than a 15% reduction in available staff time per sputum smear test in most laboratories.

Conclusion

This low-cost, ACF program has the potential to be highly cost-effective in addressing gaps in TB care problems in rural India.

Thermally Robust Porous Bimetallic (Ni xPt1- x) Alloy Mesocrystals within Carbon Framework: High-Performance Catalysts for Oxygen Reduction and Hydrogenation Reactions

Thermally stable porous bimetallic (Ni _xPt_{1- x}) alloy mesocrystals within a carbon framework are produced via an aerosol-assisted process for high-performance catalysts for the oxygen reduction reaction (ORR) and hydrogenation. The porous Ni _xPt_{1- x} alloy has a robust composite of alloy nanoparticles with an adjustable composition and a porous carbon skeleton. Porous Ni _xPt_{1- x} alloys exhibit high thermal stability, retaining their crystalline structure and morphology at 550 °C for 6 h, as observed in thermal treatment tests under various conditions (time, temperature, and atmosphere). The porous Ni _xPt_{1- x} alloy as a catalyst for the hydrogenation of propylene has high conversion efficiency (>80%) and low activation energy ( E_a < 20 kJ/mol) at ≥80 °C through the suitable control of the element composition and a pore structure. As a catalyst for the ORR, the catalytic activity of the porous Ni _xPt_{1- x} alloy is superior to that of conventional Pt/C (0.115 mA) (0.853 mA/cm_Pt² at 0.9 V/cm_Pt²). This is attributed to the homogeneous alloying of the metal components (Ni and Pt) and the increased accessibility of the reactants to the catalyst, resulting from the unique morphology of the porous Ni _xPt_{1- x} alloy, i.e., hierarchical structure with high porosity.

Minimized Volume Expansion in Hierarchical Porous Silicon upon Lithiation

Silicon (Si) remains one of the most promising anode materials for next-generation lithium-ion batteries (LIBs). The key challenge for Si anodes is the huge volume change during lithiation-delithiation cycles that leads to electrode pulverization and rapid capacity fading. Here, we report a hierarchical porous Si (hp-Si) with a tailored porous structure [tunable primary pores (20-200 nm) and secondary nanopores (∼3-10 nm)] that can effectively minimize the volume expansion. An in situ transmission electron microscopy (TEM) study revealed that the hp-Si material with the same porosity but larger primary pores can more effectively accommodate lithiation-induced volume expansion, giving rise to a much reduced apparent volume expansion on both material and electrode levels. Chemomechanical modeling revealed that because of the different relative stiffnesses of the lithiated and unlithiated Si phases, the primary pore size plays a key role in accommodating the volume expansion of lithiated Si. The higher structural stability of the hp-Si materials with larger primary pores also maintains the fast diffusion channels of the connective pores, giving rise to better power capability and capacity retention upon electrochemical cycling. Our findings point toward an optimized hp-Si material with minimal volume change during electrochemical cycling for next-generation LIBs.

CO₂ Separation Membranes Consisting of Ionic Liquid/CdO Composites

CdO nanoparticles were utilized in the fabrication of a composite membrane containing the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM+BF-4) for CO2 separation. The use of BMIM+BF-4containing CdO nanoparticles as a CO2 separator greatly improved separation performance. The ideal selectivity for CO2/N2 was 32.5 with a CO2 permeance of 57.1 GPU when CdO 4 liquid. The enhanced separation performance nanoparticles were incorporated into the BMIM+BF-4and the was attributed to increased CO2 solubility facilitated by both the free ions in BMIM+BF-4 oxide layer of the CdO nanoparticle. The CdO nanoparticles were identified with transmission electron microscopy and the physical and chemical properties of the membranes were investigated using scanning electron microscopy, Raman spectroscopy and TGA. Interestingly, we found a correlation between CO2 permeance and electronegativity differences between the metal and oxygen for CO2 separation membrane. The electronegativity differences between the metal and oxygen was ZnO (1.79) > CdO (1.75) > CuO (1.54) > AgO (1.51). The order of CO2 permeance was ZnO in BMIM+BF-4 (101 GPU) > CdO in BMIM+BF-4 (57.1 GPU) > CuO in BMIM+BF-4 (52.4 GPU) > AgO in BMIM+BF-4 (14.1 GPU).

Novel Flexible Transparent Conductive Films with Enhanced Chemical and Electromechanical Sustainability: TiO2 Nanosheet-Ag Nanowire Hybrid

Flexible transparent conductive films (TCFs) of TiO₂ nanosheet (TiO₂ NS) and silver nanowire (Ag NW) network hybrid were prepared through a simple and scalable solution-based process. The as-formed TiO₂ NS-Ag NW hybrid TCF shows a high optical transmittance (TT: 97% (90.2% including plastic substrate)) and low sheet resistance (R_s: 40 Ω/sq). In addition, the TiO₂ NS-Ag NW hybrid TCF exhibits a long-time chemical/aging and electromechanical stability. As for the chemical/aging stability, the hybrid TCF of Ag NW and TiO₂ NS reveals a retained initial conductivity (ΔR_s/R_s < 1%) under ambient oxidant gas over a month, superior to that of bare Ag NW (ΔR_s/R_s > 4000%) or RuO₂ NS-Ag NW hybrid (ΔR_s/R_s > 200%). As corroborated by the density functional theory simulation, the superb chemical stability of TiO₂ NS-Ag NW hybrid is attributable to the unique role of TiO₂ NS as a barrier, which prevents Ag NW's chemical corrosion via the attenuated adsorption of sulfidation molecules (H₂S) on TiO₂ NS. With respect to the electromechanical stability, in contrast to Ag NWs (ΔR/R₀ ∼ 152.9%), our hybrid TCF shows a limited increment of fractional resistivity (ΔR/R₀ ∼ 14.4%) after 200 000 cycles of the 1R bending test (strain: 6.7%) owing to mechanically welded Ag NW networks by TiO₂ NS. Overall, our unique hybrid of TiO₂ NS and Ag NW exhibits excellent electrical/optical properties and reliable chemical/electromechanical stabilities.

A graphene mesh as a hybrid electrode for foldable devices

A graphene mesh with arrays of micro-holes was fabricated on a polymer substrate using photolithography for use as an electrode in flexible devices. The optimal mesh structure with high optical transmittance and electrical conductivity was designed using a finite element method, in which the conductivity of the mesh was simulated as a function of structure, size, and periodicity of the hole array. The sheet resistance of the graphene mesh was lowered to that of a graphene monolayer by chemical doping and found to be 330 Ω Sq^-1 at 98.5% transparency. The figure of merit of the doped graphene mesh was calculated to be 106 at 98% transmittance, a value that has not yet been reported for any conventional transparent electrode material. Due to strong bonding between the polymer and substrate, the hybrid electrode composed of a silver nanowire (AgNW)/graphene mesh coated with an over-coating layer exhibited more stable electrical characteristics during mechanical fatigue deformation compared to a hybrid film composed of a AgNW/graphene sheet. The AgNW/graphene sheet underwent breakdown at less than 20 000 cycles in cyclic bending tests with 6.5% strain, but the AgNW/graphene mesh showed a 38% increase in resistance at 20 000 cycles and no breakdown even at 100 000 cycles. Therefore, in this study, we propose a hybrid structure composed of a AgNW/graphene mesh, which is optically and mechanically superior to AgNW/graphene sheets, and therefore suitable for application as a transparent electrode in foldable devices with long-term stability.

Correction: Direct characterization of graphene doping state by in situ photoemission spectroscopy with Ar gas cluster ion beam sputtering

Correction for ‘Direct characterization of graphene doping state by in situ photoemission spectroscopy with Ar gas cluster ion beam sputtering’ by Dong-Jin Yun et al., Phys. Chem. Chem. Phys., 2018, 20, 615–622.

Direct characterization of graphene doping state by in situ photoemission spectroscopy with Ar gas cluster ion beam sputtering

On the basis of an in situ photoemission spectroscopy (PES) system, we propose a novel, direct diagnosis method for the characterization of graphene (Gr) doping states at organic semiconductor (OSC)/electrode interfaces. Our in situ PES system enables ultraviolet/X-ray photoelectron spectroscopy (UPS/XPS) measurements during the OSC growth or removal process. We directly deposit C₆₀ films on three different p-type dopants-gold chloride (AuCl₃), (trifluoromethyl-sulfonyl)imide (TFSI), and nitric acid (HNO₃). We periodically characterize the chemical/electronic state changes of the C₆₀/Gr structures during their aging processes under ambient conditions. Depositing the OSC on the p-type doped Gr also prevents severe degradation of the electrical properties, with almost negligible transition over one month, while the p-type doped Gr without an OSC changes a lot following one month of aging. Our results indicate that the chemical/electronic structures of the Gr layer are completely reflected in the energy level alignments at the C₆₀/Gr interfaces. Therefore, we strongly believe that the variation of energy level alignments at the OSC/graphene interface is a key standard for determining the doping state of graphene after a certain period of aging.

Mechanically Robust Magnetic Carbon Nanotube Papers Prepared with CoFe2O4 Nanoparticles for Electromagnetic Interference Shielding and Magnetomechanical Actuation

The introduction of inorganic nanoparticles into carbon nanotube (CNT) papers can provide a versatile route to the fabrication of CNT papers with diverse functionalities, but it may lead to a reduction in their mechanical properties. Here, we describe a simple and effective strategy for the fabrication of mechanically robust magnetic CNT papers for electromagnetic interference (EMI) shielding and magnetomechanical actuation applications. The magnetic CNT papers were produced by vacuum filtration of an aqueous suspension of CNTs, CoFe₂O₄ nanoparticles, and poly(vinyl alcohol) (PVA). PVA plays a critical role in enhancing the mechanical strength of CNT papers. The magnetic CNT papers containing 73 wt % of CoFe₂O₄ nanoparticles exhibited high mechanical properties with Young's modulus of 3.2 GPa and tensile strength of 30.0 MPa. This magnetic CNT paper was successfully demonstrated as EMI shielding paper with shielding effectiveness of ∼30 dB (99.9%) in 0.5-1.0 GHz, and also as a magnetomechanical actuator in an audible frequency range from 200 to 20 000 Hz.

Isolated, well-defined organovanadium(iii) on silica: single-site catalyst for hydrogenation of alkenes and alkynes

Well-defined, isolated, single-site organovanadium(iii) catalyst on SiO₂ for unprecedented liquid- and gas-phase hydrogenation of alkenes and alkynes under mild conditions.

Facile synthesis of a mesostructured TiO2–graphitized carbon (TiO2–gC) composite through the hydrothermal process and its application as the anode of lithium ion batteries

A mesostructured TiO₂–graphitic carbon (TiO₂–gC) composite was synthesized through a simple and scalable one-step hydrothermal method, exhibiting high capacity, advanced rate capability and a very stable cycle life.

Treatment of pseudohypoparathyroidism with 1 alpha-hydroxyvitamin D3

A maintenance dosis of 2 microgram/day of 1 alpha-OH-D3 could keep the level of serum calcium normal in all 5 cases with pseudohypoparathyroidism, in contrast with 4.0 +/- 1.26 microgram/day needed for the 11 cases with hypoparathyroidism (8 idiopathic and 3 postoperative). The conspicuous effect of 1 alpha-OH-D3 on pseudohypoparathyroidism is likely to be attributed to the fact that the unresponsiveness of bone tissue to parathyroid hormone is corrected by the action of active vitamin D.

Porous spherical carbon/sulfur nanocomposites by aerosol-assisted synthesis: the effect of pore structure and morphology on their electrochemical performance as lithium/sulfur battery cathodes

Porous spherical carbons (PSCs) with tunable pore structure (pore volume, pore size, and surface area) were prepared by an aerosol-assisted process. PSC/sulfur composites (PSC/S, S: ca.59 wt %) were then made and characterized as cathodes in lithium/sulfur batteries. The relationships between the electrochemical performance of PSC/S composites and their pore structure and particle morphology were systematically investigated. PSC/S composite cathodes with large pore volume (>2.81 cm(3)/g) and pore size (>5.10 nm) were found to exhibit superior electrochemical performance, likely due to better mass transport in the cathode. In addition, compared with irregularly shaped carbon/sulfur composite, the spherical shaped PSC/S composite showed better performance due to better electrical contact among the particles.