Determination of estrogens in human serum using a novel chemical derivatization-assisted liquid chromatography-electrospray ionization-tandem mass spectrometry method.

RATIONALE: Assessing estrogen concentrations in biological systems can provide valuable information on physiological processes, which is crucial for the early diagnosis of many diseases. Because estrogens are present in the human body in low concentrations and in a wide dynamic range, analytical methods with high sensitivity and specificity are required for their determination in complex biological matrices. METHODS: To discover an appropriate derivatization reagent for estrogen mass spectrometry (MS) analysis, we compared five sulfonyl chloride derivatization reagents, namely 3-methyl-8-quinolinesulfonyl chloride (MQSCl) and 8-quinolinesulfonyl chloride (QSCl), 1-methyl-1H-pyrazole-4-sulfonyl chloride, 1,2-methyl-imidazole-5-sulfonyl chloride, and dansyl chloride. By selecting the derivatization reagent with the best performance, we developed and validated a novel chemical derivatization-assisted-liquid chromatography-electrospray ionization-tandem mass spectrometry (CD-LC-ESI-MS/MS) method to simultaneously determine the concentrations of estrone, estradiol, and estriol (E1, E2, and E3) in human serum. RESULTS: It was found that among the five investigated reagents, MQSCl-derivatized estrogens presented the highest sensitivity using LC-ESI-MS/MS. Based on this discovery, MQSCl was chosen to derivatize the analyzed estrogens to assist LC-ESI-MS/MS analysis. The limit of quantification of E1, E2, and E3 was measured as 2.7, 4.6, and 5.1 pg/mL, respectively. Inter- and intra-day precision, expressed as the coefficient of variation, was shown to be lower than 13.2% for all concentrations. The mean recovery was 72.4% overall, with good reproducibility at low, medium, and high concentrations in the calibration range. CONCLUSIONS: The developed method was successfully applied to the quantitative determination of estrogens in clinical human serum from pediatric and adult women, demonstrating the suitability of estrogen analysis in the biological matrix at low concentration (pg/mL).

Identification of Chemical Vapor Mixture Assisted by Artificially Extended Database for Environmental Monitoring.

A fully integrated sensor array assisted by pattern recognition algorithm has been a primary candidate for the assessment of complex vapor mixtures based on their chemical fingerprints. Diverse prototypes of electronic nose systems consisting of a multisensory device and a post processing engine have been developed. However, their precision and validity in recognizing chemical vapors are often limited by the collected database and applied classifiers. Here, we present a novel way of preparing the database and distinguishing chemical vapor mixtures with small data acquisition for chemical vapors and their mixtures of interest. The database for individual vapor analytes is expanded and the one for their mixtures is prepared in the first-order approximation. Recognition of individual target vapors of NO2, HCHO, and NH3 and their mixtures was evaluated by applying the support vector machine (SVM) classifier in different conditions of temperature and humidity. The suggested method demonstrated the recognition accuracy of 95.24%. The suggested method can pave a way to analyze gas mixtures in a variety of industrial and safety applications.

Polarization- and Electrode-Optimized Polyvinylidene Fluoride Films for Harsh Environmental Piezoelectric Nanogenerator Applications.

While piezoelectric nanogenerators have demonstrated the effective conversion of tiny mechanical vibrations to electricity, their performances are rarely examined under harsh environmental conditions. Here, a multilayered polyvinylidene fluoride (PVDF) film-based piezoelectric nanogenerator (ML-PENG) is demonstrated to generate considerable and stable power outputs even at extremely low temperatures and pressures, and under strong UV. Up-/down-polarized PVDF films are alternately stacked, and Ag electrodes are intercalated between the two adjacent films. At -266 °C and 10-5  Torr, the ML-PENG generates an open-circuit voltage of 1.1 V, a short-circuit current density of 8 nA cm-2 , and a power density of 4.4 nW cm-2 . The piezoelectric outputs are quite stable against prolonged illumination of UV, large temperature- and pressure-variations, and excessive mechanical vibrations. The piezoelectric power density is greatly enhanced above the freezing and glass transition temperatures of PVDF and recorded to be 10, 105, and 282 nW cm-2 at -73, 0, and 77 °C, respectively. The ML-PENG generates sufficient power to operate five light-emitting diodes by harvesting biomechanical energy under simulated Martian conditions. This work suggests that polarization- and electrode-optimized ML-PENG can serve as a reliable and economic power source in harsh and inaccessible environments like polar areas of Earth and extraterrestrial Mars.

Metal Oxide Nanorods-Based Sensor Array for Selective Detection of Biomarker Gases.

The breath gas analysis through gas phase chemical analysis draws attention in terms of non-invasive and real time monitoring. The array-type sensors are one of the diagnostic methods with high sensitivity and selectivity towards the target gases. Herein, we presented a 2 × 4 sensor array with a micro-heater and ceramic chip. The device is designed in a small size for portability, including the internal eight-channel sensor array. In2O3 NRs and WO3 NRs manufactured through the E-beam evaporator's glancing angle method were used as sensing materials. Pt, Pd, and Au metal catalysts were decorated for each channel to enhance functionality. The sensor array was measured for the exhaled gas biomarkers CH3COCH3, NO2, and H2S to confirm the respiratory diagnostic performance. Through this operation, the theoretical detection limit was calculated as 1.48 ppb for CH3COCH3, 1.9 ppt for NO2, and 2.47 ppb for H2S. This excellent detection performance indicates that our sensor array detected the CH3COCH3, NO2, and H2S as biomarkers, applying to the breath gas analysis. Our results showed the high potential of the gas sensor array as a non-invasive diagnostic tool that enables real-time monitoring.

Cellular Auxetic Structures for Mechanical Metamaterials: A Review.

Recent advances in lithography technology and the spread of 3D printers allow us a facile fabrication of special materials with complicated microstructures. The materials are called "designed materials" or "architectured materials" and provide new opportunities for material development. These materials, which owing to their rationally designed architectures exhibit unusual properties at the micro- and nano-scales, are being widely exploited in the development of modern materials with customized and improved performance. Meta-materials are found to possess superior and unusual properties as regards static modulus (axial stress divided by axial strain), density, energy absorption, smart functionality, and negative Poisson's ratio (NPR). However, in spite of recent developments, it has only been feasible to fabricate a few such meta-materials and to implement them in practical applications. Against such a backdrop, a broad review of the wide range of cellular auxetic structures for mechanical metamaterials available at our disposal and their potential application areas is important. Classified according to their geometrical configuration, this paper provides a review of cellular auxetic structures. The structures are presented with a view to tap into their potential abilities and leverage multidimensional fabrication advances to facilitate their application in industry. In this review, there is a special emphasis on state-of-the-art applications of these structures in important domains such as sensors and actuators, the medical industry, and defense while touching upon ways to accelerate the material development process.

Self-Powered Chemical Sensing Driven by Graphene-Based Photovoltaic Heterojunctions with Chemically Tunable Built-In Potentials.

Ultralow power chemical sensing is essential toward realizing the Internet of Things. However, electrically driven sensors must consume power to generate an electrical readout. Here, a different class of self-powered chemical sensing platform based on unconventional photovoltaic heterojunctions consisting of a top graphene (Gr) layer in contact with underlying photoactive semiconductors including bulk silicon and layered transition metal dichalcogenides is proposed. Owing to the chemically tunable electrochemical potential of Gr, the built-in potential at the junction is effectively modulated by absorbed gas molecules in a predictable manner depending on their redox characteristics. Such ability distinctive from bulk photovoltaic counterparts enables photovoltaic-driven chemical sensing without electric power consumption. Furthermore, it is demonstrated that the hydrogen (H2 ) sensing properties are independent of the light intensity, but sensitive to the gas concentration down to the 1 ppm level at room temperature. These results present an innovative strategy to realize extremely energy-efficient sensors, providing an important advancement for future ubiquitous sensing.

Ionic-Activated Chemiresistive Gas Sensors for Room-Temperature Operation.

The development of high performance gas sensors that operate at room temperature has attracted considerable attention. Unfortunately, the conventional mechanism of chemiresistive sensors is restricted at room temperature by insufficient reaction energy with target molecules. Herein, novel strategy for room temperature gas sensors is reported using an ionic-activated sensing mechanism. The investigation reveals that a hydroxide layer is developed by the applied voltages on the SnO2 surface in the presence of humidity, leading to increased electrical conductivity. Surprisingly, the experimental results indicate ideal sensing behavior at room temperature for NO2 detection with sub-parts-per-trillion (132.3 ppt) detection and fast recovery (25.7 s) to 5 ppm NO2 under humid conditions. The ionic-activated sensing mechanism is proposed as a cascade process involving the formation of ionic conduction, reaction with a target gas, and demonstrates the novelty of the approach. It is believed that the results presented will open new pathways as a promising method for room temperature gas sensors.

A Ru-Pt alloy electrode to suppress leakage currents of dynamic random-access memory capacitors.

Rutile TiO2, a high temperature phase, has attracted interest as a capacitor dielectric in dynamic random-access memories (DRAMs). Despite its high dielectric constant of >80, large leakage currents caused by a low Schottky barrier height at the TiO2/electrode interface have hindered the use of rutile TiO2 as a commercial DRAM capacitor. Here, we propose a new Ru-Pt alloy electrode to increase the height of the Schottky barrier. The Ru-Pt mixed layer was grown by atomic layer deposition. The atomic ratio of Ru/Pt varied in the entire range from 100 at.% Ru to 100 at.% Pt. Rutile TiO2 films were inductively formed only on the Ru-Pt layer containing ≤43 at.% Pt, while anatase TiO2 films with a relatively low dielectric constant (∼40) were formed at Pt compositions > 63 at.%. The Ru-Pt (40-50 at.%) layer also attained an increase in work function of ∼0.3-0.4 eV, leading to an improvement in the leakage currents of the TiO2/Ru-Pt capacitor. These findings suggested that a Ru-Pt layer could serve as a promising electrode for next-generation DRAM capacitors.

Highly Sensitive Sensors Based on Metal-Oxide Nanocolumns for Fire Detection.

A fire detector is the most important component in a fire alarm system. Herein, we present the feasibility of a highly sensitive and rapid response gas sensor based on metal oxides as a high performance fire detector. The glancing angle deposition (GLAD) technique is used to make the highly porous structure such as nanocolumns (NCs) of various metal oxides for enhancing the gas-sensing performance. To measure the fire detection, the interface circuitry for our sensors (NiO, SnO2, WO3 and In2O3 NCs) is designed. When all the sensors with various metal-oxide NCs are exposed to fire environment, they entirely react with the target gases emitted from Poly(vinyl chlorides) (PVC) decomposed at high temperature. Before the emission of smoke from the PVC (a hot-plate temperature of 200 °C), the resistances of the metal-oxide NCs are abruptly changed and SnO2 NCs show the highest response of 2.1. However, a commercial smoke detector did not inform any warning. Interestingly, although the NiO NCs are a p-type semiconductor, they show the highest response of 577.1 after the emission of smoke from the PVC (a hot-plate temperature of 350 °C). The response time of SnO2 NCs is much faster than that of a commercial smoke detector at the hot-plate temperature of 350 °C. In addition, we investigated the selectivity of our sensors by analyzing the responses of all sensors. Our results show the high potential of a gas sensor based on metal-oxide NCs for early fire detection.

Evaluation of Urinary Indices for Albuminuria and Proteinuria in Patients with Chronic Kidney Disease.

BACKGROUND/AIMS: Either protein-to-creatinine ratio (PCR) or albumin-to-creatinine ratio (ACR) can be adopted for estimation of proteinuria in patients with chronic kidney disease (CKD). Estimated protein excretion rate (ePER) and estimated albumin excretion rate (eAER) may be superior to ACR and PCR. Reports show that urine albumin-to-protein ratio (APR) may be useful in detecting tubular proteinuria, but should be compared with urine protein electrophoresis (PEP). METHODS: Both 24-h urine and spot urine were collected from 77 stable CKD patients for measurement of albumin, protein, and creatinine, and PEP. Based on MDRD and CKD-EPI equations, ePERMDRD, ePERCKD-EPI, eAERMDRD and eAERCKD-EPI were calculated to estimate daily proteinuria and albuminuria. Glomerular CKD was defined by clinical and/or pathological evidence. RESULTS: ACR correlated significantly with PCR. However, microalbuminuria was present in patients without pathologic proteinuria. Twenty-four-hour urine albumin correlated better with eAERMDRD and eAERCKD-EPI than ACR, and 24-h urine protein correlated better with ePERMDRD and ePERCKD-EPI than PCR. APR significantly but not well correlated with the albumin fraction in urine PEP. The albumin fraction obtained from urine PEP was significantly higher in patients with glomerulopathy than those with non-glomerular CKD, whereas there were no differences in APR between groups. In contrast with APR, the albumin fraction in urine PEP was independently associated with glomerular CKD. CONCLUSIONS: Both PCR and ACR are useful in evaluation of proteinuria. In quantifying daily proteinuria and albuminuria, ePER and eAER are superior to PCR and ACR, respectively. Compared with APR, urine PEP is more useful in diagnosing glomerular proteinuria.

Control of the initial growth in atomic layer deposition of Pt films by surface pretreatment.

The controllability of the nucleation behavior of Pt in atomic layer deposition (ALD) by surface pretreatments with H2O, H2S, and NH3 was investigated. The H2O pretreatment on SiO2 and TiO2 surfaces had little effect on the nucleation of Pt. The H2S pretreatment on the SiO2 and TiO2 surfaces significantly delayed the nucleation of Pt on them, while the NH3 pretreatment on the TiO2 surface led to fluent nucleation of Pt. In particular, a continuous Pt film was successfully formed even at an ultrathin thickness of approximately 2.2 nm by NH3 pretreatment. This work suggests that the pretreatment with H2S and NH3 is an efficient way to control the nucleation of Pt in ALD without the support of any reactive species, such as plasma or O3. Such a strategy enables the easy control of the size and distribution density of Pt nanoparticles for a wide range of applications.

High-efficiency large-bandgap material for polymer solar cells.

High-molecular-weight conjugated polymer HD-PDFC-DTBT with N-(2-hexyldecyl)-3,6-difluorocarbazole as the donor unit, 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit, and thiophene as the spacer is synthesized by Suzuki polycondensation. HD-PDFC-DTBT shows a large bandgap of 1.96 eV and a high hole mobility of 0.16 cm(2) V(-1) s(-1) . HD-PDFC-DTBT:PC71 BM-based inverted polymer solar cells (PSCs) give a power conversion efficiency (PCE) of 7.39% with a Voc of 0.93 V, a Jsc of 14.11 mA cm(-2) , and an FF of 0.56.

Prognostic Significance of 1-Year Serum Albumin Levels Within the Normal Range After Kidney Transplantation.

Hypoalbuminemia is associated with poor outcomes in kidney transplantation (KT). However, what level is optimal in serum albumin is not clear for the long-term prognosis. To determine whether the long-term outcomes are different even between the normal ranges of serum albumin after KT, we analyzed data from 404 renal allograft recipients whose 1-year post-transplant serum albumin levels were within the normal limits (3.5-5.5 g/dL). During a follow-up of 122 ± 56 months, 97 graft losses, 20 patient deaths, and 50 cardiovascular (CV) events occurred. Based on 1-year serum albumin levels, the patients were divided into high normal (≥4.6 g/dL, n = 209) and low normal (<4.6 g/dL, n = 195) groups. Kaplan-Meier analyses revealed that the low normal group had poorer allograft survival (P = 0.01), patient survival (P < 0.001), and CV event-free survival (P < 0.001) than the high normal group. Cox regression analysis confirmed that 1-year serum albumin was inversely associated with the risk of graft loss (hazard ratio [HR] 0.414, 95% confidence interval [CI] 0.200-0.856), patient death (HR 0.097, 95% CI 0.019-0.484), and CV events (HR 0.228, 95% CI 0.074-0.702). In conclusion, a relatively low 1-year post-transplant serum albumin level within the normal limits (<4.6 g/dL) significantly predicts poor long-term outcomes.

Association between a change in donor kidney function and long-term allograft outcomes in kidney transplant recipients.

Reserve capacity of donated kidney may be an important determinant of allograft survival in kidney transplantation (KT). Here, we investigate change in estimated glomerular filtration rate of donor kidney (ΔeGFR(Donor)) over 30 days after KT as a predictor of the allograft function. A total of 222 recipients were divided into two groups according to ΔeGFR(Donor) as follows: Group I (n = 110), ΔeGFR(Donor) ≥ -25%; Group II (n = 112), ΔeGFR(Donor) < -25%. Three years after KT, Group I had a higher eGFR(Recipient) than Group II (55 ± 21 vs. 47 ± 22 mL/min/1.73 m2, P < 0.05). However, no differences in eGFR(Recipient) were detected between the two groups after 10 years. Linear regression analysis showed that ΔeGFR(Donor) was significantly associated with the eGFR(Recipient) at 3 years post-transplantation, but not at 10 years post-transplantation. In Kaplan-Meier analysis, Group I had a greater dialysis-free survival rate than Group II at the 10-year follow-up (84% vs. 76%, P < 0.05). However, no difference in overall survival rate between groups was detected. In the multivariate-adjusted Cox proportional-hazard model, ΔeGFR(Donor) was independently associated with future allograft loss (hazard ratio 0.973; 95% confidence interval 0.949-0.999). These results suggest that larger recovery of donor kidney function after KT donation is associated with better short/intermediate-term allograft outcomes. Follow-up assessment of donor kidney function may be useful to monitor KT recipients at risk for allograft loss.

Highly Sensitive H2S Sensor Based on the Metal-Catalyzed SnO2 Nanocolumns Fabricated by Glancing Angle Deposition.

As highly sensitive H2S gas sensors, Au- and Ag-catalyzed SnO2 thin films with morphology-controlled nanostructures were fabricated by using e-beam evaporation in combination with the glancing angle deposition (GAD) technique. After annealing at 500 °C for 40 h, the sensors showed a polycrystalline phase with a porous, tilted columnar nanostructure. The gas sensitivities (S = Rgas/Rair) of Au and Ag-catalyzed SnO2 sensors fabricated by the GAD process were 0.009 and 0.015, respectively, under 5 ppm H2S at 300 °C, and the 90% response time was approximately 5 s. These sensors showed excellent sensitivities compared with the SnO2 thin film sensors that were deposited normally (glancing angle = 0°, S = 0.48).

Planar conjugated polymers containing 9,10-disubstituted phenanthrene units for efficient polymer solar cells.

Four novel conjugated polymers (P1-4) with 9,10-disubstituted phenanthrene (PhA) as the donor unit and 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit are synthesized and characterized. These polymers are of medium bandgaps (2.0 eV), low-lying HOMO energy levels (below -5.3 eV), and high hole mobilities (in the range of 3.6 × 10(-3) to 0.02 cm(2) V(-1) s(-1) ). Bulk heterojunction (BHJ) polymer solar cells (PSCs) with P1-4:PC71 BM blends as the active layer and an alcohol-soluble fullerene derivative (FN-C60) as the interfacial layer between the active layer and cathode give the best power conversion efficiency (PCE) of 4.24%, indicating that 9,10-disubstituted PhA are potential donor materials for high-efficiency BHJ PSCs.

A ferroelectric photocatalyst for enhancing hydrogen evolution: polarized particulate suspension.

A particle-based photocatalyst with a permanent internal field prepared by a corona poling method is presented as a novel approach to enhance the hydrogen evolution reaction in a particulate-suspension system. Photocatalytic activity of K0.5Na0.5NbO3 was significantly improved by 7.4 times after the polarization.

Effect of mycophenolic acid on cyclosporin A-induced fibronectin expression in rat mesangial cells.

This study was undertaken to determine if mycophenolic acid (MPA) inhibits the profibrotic action of cyclosporin A (CsA) and, if so, to determine the molecular mechanisms involved. The effect of MPA treatment on CsA-induced signaling through the transforming growth factor-ß (TGF-ß)/Smad pathway was evaluated by immunoblot analysis in cultured primary rat mesangial cells. Treatment of cells with 1 µmol/l MPA did not significantly decrease the CsA-induced expression of TGF-ß(1), but partially reversed the increases in Smad3 phosphorylation and fibronectin (FBN) production, and increased Smad7 expression. These results suggest that MPA may ameliorate CsA-induced FBN production by modulating the Smad signaling pathway. This study provides evidence that MPA can attenuate CsA-induced renal injury after kidney transplantation.

An Artificial Olfactory System Based on a Chemi-Memristive Device.

Technologies based on the fusion of gas sensors and neuromorphic computing to mimic the olfactory system have immense potential. However, the implementation of neuromorphic olfactory systems remains in a state of infancy because conventional gas sensors lack the necessary functions. Therefore, this study proposes a hysteretic "chemi-memristive gas sensor" based on oxygen vacancy chemi-memristive dynamics that differ from that of conventional gas sensors. After the memristive switching operation, the redox reaction with the external gas molecules is enhanced, resulting in the generation and elimination of oxygen vacancies that induce rapid current changes. In addition, the pre-generated oxygen vacancies enhance the post-sensing properties. Therefore, fast responses, short recovery times, and hysteretic gas response are achieved by the proposed sensor at room temperature. Based on the advantageous functionality of the sensor, device-level olfactory systems that can monitor the history of input gas stimuli are experimentally demonstrated as a potential application. Moreover, analog conductance modulation induced by oxidizing and reducing gases enables the conversion of external gas stimuli into synaptic weights and hence the realization of typical synaptic functionalities without an additional device or circuit. The proposed chemi-memristive device represents an advance in the bioinspired technology adopted in creating artificial intelligence systems.