Polycrystalline Diamond Micro-Hotplates.

Micro-hotplate structures are increasingly being investigated for use in a host of applications ranging from broadband infra-red sources within absorption-based gas sensors to in situ heater stages for ultra-high-resolution imaging. With devices usually fabricated from a conductive electrode placed on top of a freestanding radiator element, coefficient of thermal expansion (CTE) mismatches between layers and electro-migration within the heating element typically lead to failure upon exceeding temperatures of 1600 K. In an attempt to mitigate such issues, a series of hotplates of varying geometry have been fabricated from a single layer of mechanically robust, high thermal conductivity, and low CTE boron-doped polycrystalline diamond. Upon testing under high vacuum conditions and characterization of the emission spectra, the resulting devices are shown to exhibit a grey-body like emission response and reach temperatures vastly in excess of conventional geometries of up to 2731 K at applied powers of ⩽100 mW. Characterization of the thermalization time meanwhile demonstrates rapid millisecond response times, while Raman spectroscopy reveals the performance of the devices is dictated by cumulative graphitization at elevated temperatures. As such, both diamond and sp2 carbon are shown to be promising materials for the fabrication of next-generation micro-hotplates.

Observation of Imbert-Fedorov shift in monolayer MoS2 via quantum weak measurement.

We report the experimental evidence of the Imbert-Fedorov (IF) shift in monolayer MoS2 for a fundamental Gaussian beam. Using Jones vector formalism, we have shown a novel, to the best of our knowledge, pathway to apply the quantum weak measurement technique for easy and accurate determination of the IF shift. We have revealed the dependence of IF shift over a large range of angles of incidence along with the mode of polarization of the incident light. Our experimental findings via the weak value amplification scheme are in good agreement with the theoretical analysis. The present method is a general one and can also be implemented for other materials to observe such tiny transverse shifts.

Printed oxygen gas sensor using copper-DTDTPA solid electrolyte.

We present a new method for the rapid and cost-effective fabrication of solid electrolyte-based printed potentiometric oxygen sensors working at ambient temperature using Cu-dithiolated diethylene triamine pentaacetic acid complex molecules (Cu-DTDTPA) adsorbed on Grade-1 laboratory filter paper and subsequent 3-D printing of interdigitated electrodes employing silver/silver chloride ink. The decrease in conductivity with time and frequency-dependent impedance response confirms the filter paper adsorbed Cu-DTDTPA as a solid electrolyte. A plausible structure of the Cu-DTDTPA solid electrolyte and its mechanism of reaction with oxygen are presented. A maximum sensitivity of 0.052 mV per %O2, the maximum response time of 1.15 s per %O2, a wide measurement output ranging from 14.55 mV to 17.25 mV for 20%-90% of O2 concentration, a maximum standard deviation of 0.12 mV in output voltage, almost similar trends of the response on temperature, humidity variations and ageing and high selectivity establish the sensor for use in medical ventilator applications, specifically in the COVID19 pandemic.

Ammonium Phosphate as Inhibitor to Mitigate the Corrosion of Steel Rebar in Chloride Contaminated Concrete Pore Solution.

In the present study, different amounts, i.e., 1-3 v/v% of 1 M ammonium phosphate monobasic, were used as an eco-friendly corrosion inhibitor to mitigate the corrosion of steel rebar exposed to simulated concrete pore (SCP) + 3.5 wt% NaCl solution at a prolonged duration. Potentiodynamic polarization results show that as the amount of inhibitor is increased, the corrosion resistance of steel rebar is increased. The steel rebar exposed to 3% inhibitor-containing SCP + 3.5 wt% NaCl solution exhibited nobler corrosion potential (Ecorr), the lowest corrosion current density (icorr), and 97.62% corrosion inhibition efficiency after 1 h of exposure. The steel rebars exposed to 3% inhibitor-containing SCP + 3.5 wt% NaCl solution revealed higher polarization resistance (Rp) and film resistance (Ro) with exposure periods compared to other samples owing to the formation of passive film. The scanning electron microscopy (SEM) of steel rebar exposed to 3% inhibitor-containing SCP + 3.5 wt% NaCl solution showed homogenous and uniform dendritic passive film which covers all over the surface, whereas, bare, i.e., SCP + 3.5 wt% NaCl solution exposed samples exhibited pitting and irregular morphology. Raman spectroscopy results confirm the formation of goethite (α-FeOOH), maghemite (γ-Fe2O3), and iron phosphate (FePO4) as a passive film onto the steel rebar surface exposed to 3% inhibitor-containing SCP + 3.5 wt% NaCl solution. These phases are responsible for the corrosion mitigation of steel rebar which are very protective, adherent, and sparingly soluble.

An Overview on Graphene-Metal Oxide Semiconductor Nanocomposite: A Promising Platform for Visible Light Photocatalytic Activity for the Treatment of Various Pollutants in Aqueous Medium.

Graphene is one of the most favorite materials for materials science research owing to its distinctive chemical and physical properties, such as superior conductivity, extremely larger specific surface area, and good mechanical/chemical stability with the flexible monolayer structure. Graphene is considered as a supreme matrix and electron arbitrator of semiconductor nanoparticles for environmental pollution remediation. The present review looks at the recent progress on the graphene-based metal oxide and ternary composites for photocatalysis application, especially for the application of the environmental remediation. The challenges and perspectives of emerging graphene-based metal oxide nanocomposites for photocatalysis are also discussed.

Air-clad suspended nanocrystalline diamond ridge waveguides.

A hybrid group IV ridge waveguide platform is demonstrated, with potential application across the optical spectrum from ultraviolet to the far infrared wavelengths. The waveguides are fabricated by partial etching of sub-micron ridges in a nanocrystalline diamond thin film grown on top of a silicon wafer. To create vertical confinement, the diamond film is locally undercut by exposing the chip to an isotropic fluorine plasma etch via etch holes surrounding the waveguides, resulting in a mechanically stable suspended air-clad waveguide platform. Optical characterization of the waveguides at 1550 nm yields an average optical loss of 4.67 ± 0.47 dB/mm. Further improvement to the fabrication process is expected to significantly reduce this waveguide loss.

Superconductivity in planarised nanocrystalline diamond films.

Chemical vapour deposition (CVD) grown boron-doped nanocrystalline diamond (B-NCD) is an attractive material for the fabrication of high frequency superconducting nanoelectromechanical systems (NEMS) due to its high Young's modulus. The as-grown films have a surface roughness that increases with film thickness due to the columnar growth mechanism. To reduce intrinsic losses in B-NCD NEMS it is crucial to correct for this surface roughness by polishing. In this paper, in contrast to conventional polishing, it is demonstrated that the root-mean-square (RMS) roughness of a 520 nm thick B-NCD film can be reduced by chemical mechanical polishing (CMP) from 44.0 nm to 1.5 nm in 14 hours without damaging the sample or introducing significant changes to the superconducting transition temperature, [Formula: see text], thus enabling the use of B-NCD films in the fabrication of high quality superconducting NEMS.

Effect of slurry composition on the chemical mechanical polishing of thin diamond films.

Nanocrystalline diamond (NCD) thin films grown by chemical vapour deposition have an intrinsic surface roughness, which hinders the development and performance of the films' various applications. Traditional methods of diamond polishing are not effective on NCD thin films. Films either shatter due to the combination of wafer bow and high mechanical pressures or produce uneven surfaces, which has led to the adaptation of the chemical mechanical polishing (CMP) technique for NCD films. This process is poorly understood and in need of optimisation. To compare the effect of slurry composition and pH upon polishing rates, a series of NCD thin films have been polished for three hours using a Logitech Ltd. Tribo CMP System in conjunction with a polyester/polyurethane polishing cloth and six different slurries. The reduction in surface roughness was measured hourly using an atomic force microscope. The final surface chemistry was examined using X-ray photoelectron spectroscopy and a scanning electron microscope. It was found that of all the various properties of the slurries, including pH and composition, the particle size was the determining factor for the polishing rate. The smaller particles polishing at a greater rate than the larger ones.

A PROSPECTIVE RANDOMIZED COMPARATIVE STUDY TO COMPARE THE HEMODYNAMIC AND METABOLIC STRESS RESPONE DUE TO ENDOTRACHEAL INTUBATION AND I-GEL USAGE DURING LAPAROSCOPIC CHOLECYSTECTOMY.

BACKGROUND: Surgery and endotracheal intubation both causes an increase in metabolic stress response. This is further aggravated during laparoscopic surgeries. In this study we aimed at comparing hemodynamic and metabolic parameters which are reflective of intraoperative stress response while using I-GEL against endotracheal tube (ETT) during laparoscopic cholecystectomy. MATERIAL AND METHODS: This is a prospective randomized comparative study among 64 cases of American Society of Anesthesiologists(ASA) physical status class I and II, undergoing laparoscopic cholecystectomy who were randomly allocated into two groups of 32 each using computer generated random number table. Patients were put under general anesthesia using standard protocol. After anesthesia induction and 20 minutes after induction venous blood samples were obtained for measuring adrenalin, noradrenalin, dopamine and cortisol levels. Hemodynamic and respiratory parameters were recorded at the 1st, 5th, 15th, 30th and 45th minutes after the insertion of airway device. RESULTS: Although there was no significant difference regarding ventilatory parameters there was significant increase in heart rate at 1st and 45th minutes (p = 0.02 and 0.034) respectively and increase in mean arterial pressure at 15th and 30th minutes(p = 0.034 and 0.026) respectively in the ETT group compared to I-GEL group. Stress hormone intergroup analysis revealed significant increase in serum cortisol 20 minutes after induction in ETT group as compared to I-GEL group (p = 0.03). CONCLUSION: I-GEL usage is a suitable, effective and safe alternative to ETT in laparoscopic cholecystectomy patients with lower metabolic stress response.

Silica based polishing of {100} and {111} single crystal diamond.

Diamond is one of the hardest and most difficult to polish materials. In this paper, the polishing of {111} and {100} single crystal diamond surfaces by standard chemical mechanical polishing, as used in the silicon industry, is demonstrated. A Logitech Tribo Chemical Mechanical Polishing system with Logitech SF1 Syton and a polyurethane/polyester polishing pad was used. A reduction in roughness from 0.92 to 0.23 nm root mean square and 0.31 to 0.09 nm rms for {100} and {111} samples respectively was observed.

Delayed Presentation of Mandibular Osteonecrosis Following Herpes Zoster Infection - A Case Report.

Rationale: Apart from the usual presentation of herpes zoster (HZ) infection (HZI), reports of spontaneous teeth exfoliation and osteonecrosis are infrequent and sporadic. Patient Concerns: A 51-year-old male patient presented with spontaneous exfoliation of multiple teeth and subsequent pathological fracture on the right side of the lower jaw after three months of HZI. Diagnosis: Biopsy was taken from the alveolar bone of the oedematous region, which revealed the presence of trabeculae of dead bone with empty lacunae. Intervention: Necrosed part of the alveolar bone was excised under local anaesthesia and antibiotic coverage, which was followed by open reduction and internal fixation of the pathological fracture under general anaesthesia. Outcomes: The patient was followed up for one year without any evidence of recurrences. Take-away Lessons: Presentation of osteonecrosis following HZI is unique but rare and should be diagnosed at the earliest.

Microporous poly- and monocrystalline diamond films produced from chemical vapor deposited diamond-germanium composites.

We report on a novel method for porous diamond fabrication, which is based on the synthesis of diamond-germanium composite films followed by etching of the Ge component. The composites were grown by microwave plasma assisted CVD in CH4-H2-GeH4 mixtures on (100) silicon, and microcrystalline- and single-crystal diamond substrates. The structure and the phase composition of the films before and after etching were analyzed with scanning electron microscopy and Raman spectroscopy. The films revealed a bright emission of GeV color centers due to diamond doping with Ge, as evidenced by photoluminescence spectroscopy. The possible applications of the porous diamond films include thermal management, surfaces with superhydrophobic properties, chromatography, supercapacitors, etc.

Monitoring of the Initial Stages of Diamond Growth on Aluminum Nitride Using In Situ Spectroscopic Ellipsometry.

The high thermal conductivity of polycrystalline diamond makes it ideally suited for thermal management solutions for gallium nitride (GaN) devices, with a diamond layer grown on an aluminum nitride (AlN) interlayer atop the GaN stack. However, this application is limited by the thermal barrier at the interface between diamond and substrate, which has been associated with the transition region formed in the initial phases of growth. In this work, in situ spectroscopic ellipsometry (SE) is employed to monitor early-stage microwave plasma-enhanced chemical vapor deposition diamond growth on AlN. An optical model was developed from ex situ spectra and applied to spectra taken in situ during growth. Coalescence of separate islands into a single film was marked by a reduction in bulk void fraction prior to a spike in sp2 fraction due to grain boundary formation. Parameters determined by the SE model were corroborated using Raman spectroscopy and atomic force microscopy.

Poststroke Grasp Ability Assessment Using an Intelligent Data Glove Based on Action Research Arm Test: Development, Algorithms, and Experiments.

Growing impact of poststroke upper extremity (UE) functional limitations entails newer dimensions in assessment methodologies. This has compelled researchers to think way beyond traditional stroke assessment scales during the out-patient rehabilitation phase. In concurrence with this, sensor-driven quantitative evaluation of poststroke UE functional limitations has become a fertile field of research. Here, we have emphasized an instrumented wearable for systematic monitoring of stroke patients with right-hemiparesis for evaluating their grasp abilities deploying intelligent algorithms. An instrumented glove housing 6 flex sensors, 3 force sensors, and a motion processing unit was developed to administer 19 activities of Action Research Arm Test (ARAT) while experimenting on 20 voluntarily participating subjects. After necessary signal conditioning, meaningful features were extracted, and subsequently the most appropriate ones were selected using the ReliefF algorithm. An optimally tuned support vector classifier was employed to classify patients with different degrees of disability and an accuracy of 92% was achieved supported by a high area under the receiver operating characteristic score. Furthermore, selected features could provide additional information that revealed the causes of grasp limitations. This would assist physicians in planning more effective poststroke rehabilitation strategies. Results of the one-way ANOVA test conducted on actual and predicted ARAT scores of the subjects indicated remarkable prospects of the proposed glove-based method in poststroke grasp ability assessment and rehabilitation.

Efficient Point-of-Care Detection of Uric Acid in the Human Blood Sample with an Enhanced Electrocatalytic Response Using Nanocomposites of Cobalt and Mixed-Valent Molybdenum Sulfide.

This work efficiently detects uric acid (UA) in a human blood sample using cobalt nanoparticle-immobilized mixed-valent molybdenum sulfide on the copper substrate in a point-of-care (PoC) device. The sensor electrode was fabricated by micromachining of Cu clad boards employing an engraver to generate a three-electrode system consisting of working electrode (WE), reference electrode (RE), and counter electrode (CE). The WE was subjected to physical vapor deposition of mixed-valent MoSx layers by a reaction between Mo(CO)6 and H2S at ∼200 °C using a simple setup following which CoNPs were electrochemically deposited. The RE and CE were covered with Ag/AgCl and Ag paste, respectively. A plasma separation membrane acted as the medium of UA/blood serum delivery to the electrodes. The material and electrochemical characterization confirmed that CoNPs over MoSx provided an enlarged electroactive surface for the direct electron transfer to achieve an enhanced electrocatalytic response. The binary combination of CoNPs and MoSx layers over the Cu electrode reduced the charge-transfer resistance by two times, enhanced the surface adsorption by more than two times, and yielded a high diffusion coefficient of 3.46 × 10-3 cm2/s. These interfacial effects facilitated the UA oxidation, leading to unprecedented mA range current density for UA sensing for the PoC device. The electrochemical detection tests in the PoC device revealed a sensitivity of 64.7 µA/µM cm-2, which is ∼50 times higher compared to the latest reported value (1.23 µA/µM cm-2), a high limit of detection of 5 nM, and shelf life of 6 months, confirming the synergistic effect-mediated high sensitivity under PoC settings. Interference tests confirmed no intervention of similar analytes. Tests on blood samples demonstrated a recovery percentage close to 100% in human serum UA, signifying the suitability of the nanocomposite-based sensor and the PoC device for clinical sensing applications.

Nucleation of diamond films on heterogeneous substrates: a review.

Diamond thin films are known to have properties similar to bulk diamond and have applications in both industry and fundamental studies in academia. The high surface energy of diamond makes it extremely difficult to grow diamond films on foreign substrates. Hence, to grow diamond films on non-diamond substrates, a nucleation step is needed. In this review various techniques used for diamond nucleation/seeding will be discussed. At present electrostatic seeding by diamond nanoparticles is the most commonly used seeding technique for nanocrystalline growth. In this technique the substrate is dipped in a nanodiamond solution to form a mono layer of diamond seeds. These seeds when exposed to appropriate conditions grow to form diamond layers. This technique is suitable for most substrates. For heteroepitaxial growth, bias enhanced nucleation is the primary technique. In this technique the substrate is biased to form diamond nuclei in the initial stages of growth. This technique can be used for any conducting flat surface. For growth on ceramics, polishing by diamond grit or electrostatic seeding can be used. Polishing the ceramics with diamond powder leaves small diamond particles embedded in the substrate. These small particles then act as seeds for subsequent diamond growth. Apart from these techniques, chemical nucleation, interlayer driven nucleation and mixed techniques have been discussed. The advantages and disadvantages of individual techniques have also been discussed.

Facile Detection of Blood Creatinine Using Binary Copper-Iron Oxide and rGO-Based Nanocomposite on 3D Printed Ag-Electrode under POC Settings.

Metal nanoparticles have been helpful in creatinine sensing technology under point-of-care (POC) settings because of their excellent electrocatalyst properties. However, the behavior of monometallic nanoparticles as electrochemical creatinine sensors showed limitations concerning the current density in the mA/cm2 range and wide detection window, which are essential parameters for the development of a sensor for POC applications. Herein, we report a new sensor, a reduced graphene oxide stabilized binary copper-iron oxide-based nanocomposite on a 3D printed Ag-electrode (Fe-Cu-rGO@Ag) for detecting a wide range of blood creatinine (0.01 to 1000 µM; detection limit 10 nM) in an electrochemical chip with a current density ranging between 0.185 and 1.371 mA/cm2 and sensitivity limit of 1.1 µA µM-1 cm-2 at physiological pH. Interference studies confirmed that the sensor exhibited no interference from analytes like uric acid, urea, dopamine, and glutathione. The sensor response was also evaluated to detect creatinine in human blood samples with high accuracy in less than a minute. The sensing mechanism suggested that the synergistic effects of Cu and iron oxide nanoparticles played an essential role in the efficient sensing where Fe atoms act as active sites for creatinine oxidation through the secondary amine nitrogen, and Cu nanoparticles acted as an excellent electron-transfer mediator through rGO. The rapid sensor fabrication procedure, mA/cm2 peak current density, a wide range of detection limits, low contact resistance including high selectivity, excellent linear response (R2 = 0.991), and reusability ensured the application of advanced electrochemical sensor toward the POC creatinine detection.

Effect of Chloride Ions Concentrations to Breakdown the Passive Film on Rebar Surface Exposed to L-Arginine Containing Pore Solution.

In the present study, 0.115 M L-arginine (LA) has been used as an eco-friendly inhibitor in simulated concrete pore solutions (SP-0) in order to form passive films on a steel rebar-solution interface until 144 h. Hence, 0.51 (SP-1) and 0.85 M NaCl (SP-2) were added in LA containing SP-0 solution to breakdown the passive film and to initiate corrosion reactions. The electrochemical results show that the charge transfer resistance (Rct) of steel rebar exposed to SP-1 and SP-2 solutions increased with respect to immersion periods. The sample exposed to the SP-2 solution initiated the corrosion reaction at the steel rebar-solution interface after 24 h of NaCl addition and formed pits; on the other hand, the sample without NaCl added, i.e., SP-0, showed agglomeration and dense morphology of corrosion products.

pH-controlled synthesis of sustainable lauric acid/SiO2 phase change material for scalable thermal energy storage.

Lauric acid (LA) has been recommended as economic, eco-friendly, and commercially viable materials to be used as phase change materials (PCMs). Nevertheless, there is lack of optimized parameters to produce microencapsulated PCMs with good performance. In this study, different amounts of LA have been chosen as core materials while tetraethyl orthosilicate (TEOS) as the precursor solution to form silicon dioxide (SiO2) shell. The pH of precursor solution was kept at 2.5 for all composition of microencapsulated LA. The synthesized microencapsulated LA/SiO2 has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The SEM and TEM confirm the microencapsulation of LA with SiO2. Thermogravimetric analysis (TGA) revealed better thermal stability of microencapsulated LA/SiO2 compared to pure LA. PCM with 50% LA i.e. LAPC-6 exhibited the highest encapsulation efficiency (96.50%) and encapsulation ratio (96.15%) through Differential scanning calorimetry (DSC) as well as good thermal reliability even after 30th cycle of heating and cooling process.

3-D printed electrode integrated sensing chip and a PoC device for enzyme free electrochemical detection of blood urea.

Herein we report a novel electrochemical sensing chip and a point-of-care device (PoC) for enzyme-free electrochemical detection of urea in human blood. The electrochemical sensing chip was developed by 3-D printing of conductive Ag ink and subsequent electrodeposition of AuNP-rGO nanocomposite. Material characterization of the sensing chip was conducted to find a plausible mechanism for the electrochemical reaction with urea. Subsequently, the response with varying concentrations of urea in solution and human blood samples was tested. High peak response current (~5 times than that of the highest reported value), low impedance, rapid sensor fabrication procedure, high selectivity towards urea, excellent linear response (R2 = 0.99), high sensitivity of 183 µA mM-1 cm-2, the fast response indicated by high diffusion coefficient, the limit of detection of 0.1 µM, tested shelf life of more than 6 months and recovery rate of >99% ensured the application of the developed sensor chip towards PoC urea detection test kit. A PoC device housing an electronic circuitry following the principles of linear sweep voltammetry and compatible with a sensing chip was developed. A maximum percentage error of 4.86% and maximum RSD of 3.63% confirmed the use of the PoC device for rapid urea measurements in human blood.