Correction: Sub-nL thin-film differential scanning calorimetry chip for rapid thermal analysis of liquid samples.

Correction for 'Sub-nL thin-film differential scanning calorimetry chip for rapid thermal analysis of liquid samples' by Sheng Ni et al., Lab Chip, 2023, 23, 1926-1934, https://doi.org/10.1039/D2LC01094A.

Sub-nL thin-film differential scanning calorimetry chip for rapid thermal analysis of liquid samples.

Differential scanning calorimetry (DSC) is a popular thermal analysis technique. The miniaturization of DSC on chip as thin-film DSC (tfDSC) has been pioneered for the analysis of ultrathin polymer films at temperature scan rates and sensitivities far superior to those attainable with DSC instruments. The adoption of tfDSC chips for the analysis of liquid samples is, however, confronted with various issues including sample evaporation due to the lack of sealed enclosures. Although the subsequent integration of enclosures has been demonstrated in various designs, rarely did those designs exceed the scan rates of DSC instruments mainly because of their bulky features and requirement for exterior heating. Here, we present a tfDSC chip featuring sub-nL thin-film enclosures integrated with resistance temperature detectors (RTDs) and heaters. The chip attains an unprecedented sensitivity of 11 V W-1 and a rapid time constant of 600 ms owing to its low-addenda design and residual heat conduction (∼6 µW K-1). We present results on the phase transition of common liquid crystals which we leverage to calibrate the RTDs and characterize the thermal lag with scan rates up to 900 °C min-1. We then present results on the heat denaturation of lysozyme at various pH values, concentrations, and scan rates. The chip can provide excess heat capacity peaks and enthalpy change steps without much alteration induced by the thermal lag at elevated scan rates up to 100 °C min-1, which is an order of magnitude faster than those of many chip counterparts.

Improvement of the signal to noise ratio for fluorescent imaging in microfluidic chips.

Microfluidics systems can be fabricated in various ways using original silicon glass systems, with easy Si processing and surface modifications for subsequent applications such as cell seeding and their study. Fluorescent imaging of cells became a standard technique for the investigation of cell behavior. Unfortunately, high sensitivity fluorescent imaging, e.g., using total internal reflection fluorescence (TIRF) microscopy, is problematic in these microfluidic systems because the uneven surfaces of the silicon channels' bottoms affect light penetration through the optical filters. In this work, we study the nature of the phenomenon, finding that the problem can be rectified by using a silicon-on-insulator (SOI) substrate, defining the channel depth by the thickness of the top Si layer, and halting the etching at the buried SiO2 layer. Then the fluorescent background signal drops by = 5 times, corresponding to the limit of detection drop from = 0.05 mM to = 50 nM of fluorescein. We demonstrate the importance of a flat surface using TIRF-based single-molecule detection, improving the signal to a noise ratio more than 18 times compared to a conventional Si wafer. Overall, using very high-quality SOI substrates pays off, as it improves the fluorescence image quality due to the increase in signal-to-noise ratio. Concerning the cost of microfluidic device fabrication-design, mask fabrication, wafer processing, and device testing-the initial SOI wafer cost is marginal, and using it improves the system performance.

An image-to-answer algorithm for fully automated digital PCR image processing.

The digital polymerase chain reaction (dPCR) is an irreplaceable variant of PCR techniques due to its capacity for absolute quantification and detection of rare deoxyribonucleic acid (DNA) sequences in clinical samples. Image processing methods, including micro-chamber positioning and fluorescence analysis, determine the reliability of the dPCR results. However, typical methods demand high requirements for the chip structure, chip filling, and light intensity uniformity. This research developed an image-to-answer algorithm with single fluorescence image capture and known image-related error removal. We applied the Hough transform to identify partitions in the images of dPCR chips, the 2D Fourier transform to rotate the image, and the 3D projection transformation to locate and correct the positions of all partitions. We then calculated each partition's average fluorescence amplitudes and generated a 3D fluorescence intensity distribution map of the image. We subsequently corrected the fluorescence non-uniformity between partitions based on the map and achieved statistical results of partition fluorescence intensities. We validated the proposed algorithms using different contents of the target DNA. The proposed algorithm is independent of the dPCR chip structure damage and light intensity non-uniformity. It also provides a reliable alternative to analyze the results of chip-based dPCR systems.

Synthesis and Structure of Oxygen Deficient Lead-Technetium Pyrochlore, the First Example of a Valence V Technetium Oxide.

The structure of lead-technetium pyrochlore has been refined in space group F d 3 ¯ m with a = 10.36584(2) Å using a combination of synchrotron X-ray and neutron powder diffraction data and confirmed via Electron Diffraction. The oxide is found to be oxygen deficient with a stoichiometry of Pb2Tc2O7-d. Displacive disorder of the Pb cations is evident from the refinements, as has been observed in Bi2Tc2O7-d. X-ray absorption spectroscopic measurements at the Tc K-edge demonstrate the valence of the Tc is greater than 4.0 as anticipated from the refined oxygen stoichiometry. Raman spectroscopy confirms the presence of disorder leading us to conclude that this pyrochlore is the first example of a valence V technetium oxide.

Design and development of a new type of phimosis dilatation retractor for children.

BACKGROUND: Phimosis is one of the most common diseases in children. Early selection of appropriate treatment for phimosis in children is beneficial to the development of their reproductive organs and significantly improves the prognosis of phimosis in children. Although traditional circumcision is the most widely used, it has many disadvantages, including postoperative bleeding and incision infection, pain, obvious scars on the surgical incision, and unsatisfactory appearance. In addition, there is much controversy regarding treatment options and timing at home and abroad. Surgical procedures such as circumcision and cerclage for children with excessively long foreskin will greatly affect the normal life of children after the operation. Young children need general anesthesia, but this anesthesia carries a great risk. AIM: To design a new children phimosis dilatation retractor for children phimosis. METHODS: The children phimosis was dilated with an elastic dilation frame, in order to expand the foreskin mouth and expose the penis head, and after that, the phimosis was cured. RESULTS: A new type of phimosis dilatation retractor was designed, which can gently dilate the prepuce at multiple angles and in multiple directions at the same time. It has obtained the national patent for clinical application. CONCLUSION: The phimosis dilatation retractor based on the principle of elastically expanding the prepuce can achieve the purpose of expanding the phimosis. The clinical application shows that the effect of the children phimosis retractor is significant, which is worth promoting.

Multiplexed digital polymerase chain reaction as a powerful diagnostic tool.

The digital polymerase chain reaction (dPCR) multiplexing method can simultaneously detect and quantify closely related deoxyribonucleic acid sequences in complex mixtures. The dPCR concept is continuously improved by the development of microfluidics and micro- and nanofabrication, and different complex techniques are introduced. In this review, we introduce dPCR techniques based on sample compartmentalization, droplet- and chip-based systems, and their combinations. We then discuss dPCR multiplexing methods in both laboratory research settings and advanced or routine clinical applications. We focus on their strengths and weaknesses with regard to the character of biological samples and to the required precision of such analysis, as well as showing recently published work based on those methods. Finally, we envisage possible future achievements in this field.

PCR past, present and future.

PCR has become one of the most valuable techniques currently used in bioscience, diagnostics and forensic science. Here we review the history of PCR development and the technologies that have evolved from the original PCR method. Currently, there are two main areas of PCR utilization in bioscience: high-throughput PCR systems and microfluidics-based PCR devices for point-of-care (POC) applications. We also discuss the commercialization of these techniques and conclude with a look into their modifications and use in innovative areas of biomedicine. For example, real-time reverse transcription PCR is the gold standard for SARS-CoV-2 diagnoses. It could also be used for POC applications, being a key component of the sample-to-answer system.

The vision of point-of-care PCR tests for the COVID-19 pandemic and beyond.

Infectious diseases, such as the most recent case of coronavirus disease 2019, have brought the prospect of point-of-care (POC) diagnostic tests into the spotlight. A rapid, accurate, low-cost, and easy-to-use test in the field could stop epidemics before they develop into full-blown pandemics. Unfortunately, despite all the advances, it still does not exist. Here, we critically review the limited number of prototypes demonstrated to date that is based on a polymerase chain reaction (PCR) and has come close to fulfill this vision. We summarize the requirements for the POC-PCR tests and then go on to discuss the PCR product-detection methods, the integration of their functional components, the potential applications, and other practical issues related to the implementation of lab-on-a-chip technologies. We conclude our review with a discussion of the latest findings on nucleic acid-based diagnosis.

IoT PCR for pandemic disease detection and its spread monitoring.

During infectious disease outbreaks, the centers for disease control need to monitor particular areas. Considerable effort has been invested in the development of portable, user-friendly, and cost-effective systems for point-of-care (POC) diagnostics, which could also create an Internet of Things (IoT) for healthcare via a global network. However, at present IoT based on a functional POC instrument is not available. Here we show a fast, user-friendly, and affordable IoT system based on a miniaturized polymerase chain reaction device. We demonstrated the system's capability by amplification of complementary deoxyribonucleic acid (cDNA) of the dengue fever virus. The resulting data were then automatically uploaded via a Bluetooth interface to an Android-based smartphone and then wirelessly sent to a global network, instantly making the test results available anywhere in the world. The IoT system presented here could become an essential tool for healthcare centers to tackle infectious disease outbreaks identified either by DNA or ribonucleic acid.

Rapid Characterization of Biomolecules' Thermal Stability in a Segmented Flow-Through Optofluidic Microsystem.

Optofluidic devices combining optics and microfluidics have recently attracted attention for biomolecular analysis due to their high detection sensitivity. Here, we show a silicon chip with tubular microchannels buried inside the substrate featuring temperature gradient (∇T) along the microchannel. We set up an optical fluorescence system consisting of a power-modulated laser light source of 470 nm coupled to the microchannel serving as a light guide via optical fiber. Fluorescence was detected on the other side of the microchannel using a photomultiplier tube connected to an optical fiber via a fluorescein isothiocyanate filter. The PMT output was connected to a lock-in amplifier for signal processing. We performed a melting curve analysis of a short dsDNA - SYBR Green I complex with a known melting temperature (TM) in a flow-through configuration without gradient to verify the functionality of the proposed detection system. We then used the segmented flow configuration and measured the fluorescence amplitude of a droplet exposed to ∇T of ≈ 2.31 °C mm-1, determining the heat transfer time as ≈ 554 ms. The proposed platform can be used as a fast and cost-effective system for performing either MCA of dsDNAs or for measuring protein unfolding for drug-screening applications.

Recent advances in lab-on-a-chip technologies for viral diagnosis.

The global risk of viral disease outbreaks emphasizes the need for rapid, accurate, and sensitive detection techniques to speed up diagnostics allowing early intervention. An emerging field of microfluidics also known as the lab-on-a-chip (LOC) or micro total analysis system includes a wide range of diagnostic devices. This review briefly covers both conventional and microfluidics-based techniques for rapid viral detection. We first describe conventional detection methods such as cell culturing, immunofluorescence or enzyme-linked immunosorbent assay (ELISA), or reverse transcription polymerase chain reaction (RT-PCR). These methods often have limited speed, sensitivity, or specificity and are performed with typically bulky equipment. Here, we discuss some of the LOC technologies that can overcome these demerits, highlighting the latest advances in LOC devices for viral disease diagnosis. We also discuss the fabrication of LOC systems to produce devices for performing either individual steps or virus detection in samples with the sample to answer method. The complete system consists of sample preparation, and ELISA and RT-PCR for viral-antibody and nucleic acid detection, respectively. Finally, we formulate our opinions on these areas for the future development of LOC systems for viral diagnostics.

Tailoring exchange bias in ferro/antiferromagnetic FePt3 bilayers created by He+ beams.

We report on artificial exchange bias created in a continuous epitaxial FePt3 film by introducing chemical disorder using a He+ beam, which features tailorable exchange bias strength through post-irradiation annealing. By design, the ferromagnetic (FM)/antiferromagnetic (AF) heterostructure exhibits stratified degrees of chemical order; however, the chemical composition and stoichiometry are invariant throughout the film volume. This uniquely allows for a consideration purely of the magnetic exchange across the FM/AF interface without the added hindrance of structural boundary parameters which inherently affect exchange bias quality. Annealing at 840 K results in the strongest exchange biased system, which displays a cross-sectional morphology of fine (<10 nm) domain structure composed of both of chemically ordered and chemically disordered domains. A magnetic model developed from fitting the characteristic polarised neutron reflectometry spectral features reveals that dual interactions can be attributed to the observed exchange bias: magnetic coupling at the FM/AF interface and also between neighbouring FM (chemically disordered) and AF (chemically ordered) domains within the nominally FM layer. Our results indicate that exchange bias is hindered at interfaces which are both chemically and magnetically perfect, while annealing can be used to balance the volume proportions of interfacial FM and AF domains to enhance the magnetic interface roughness for customisable exchange bias in mono-stoichiometric FM/AF heterostructures crafted by ion beams.

Direct Measurement of the Intrinsic Sharpness of Magnetic Interfaces Formed by Chemical Disorder Using a He+ Beam.

Using ion beams to locally modify material properties and subsequently drive magnetic phase transitions is rapidly gaining momentum as the technique of choice for the fabrication of magnetic nanoelements. This is because the method provides the capability to engineer in three dimensions on the nanometer length scale. This will be an important consideration for several emerging magnetic technologies (e.g., spintronic devices and racetrack and random-access memories) where device functionality will hinge on the spatial definition of the incorporated magnetic nanoelements. In this work, the fundamental sharpness of a magnetic interface formed by nanomachining FePt3 films using He+ irradiation is investigated. Through careful selection of the irradiating ion energy and fluence, room-temperature ferromagnetism is locally induced into a fractional volume of a paramagnetic (PM) FePt3 film by modifying the chemical order parameter. A combination of transmission electron microscopy, magnetometry, and polarized neutron reflectometry measurements demonstrates that the interface over which the PM-to-ferromagnetic modulation occurs in this model system is confined to a few atomic monolayers only, while the structural boundary transition is less well-defined. Using complementary density functional theory, the mechanism for the ion-beam-induced magnetic transition is elucidated and shown to be caused by an intermixing of Fe and Pt atoms in antisite defects above a threshold density.

A reliable and highly efficient exfoliation method for water-dispersible MoS2 nanosheet.

Since the pioneering work on exfoliated single-layer graphene, layered inorganic nanosheet materials have been widely explored due to their unusual properties with potential applications in energy devices and optical electronics. Among these layered inorganic nanosheets, two-dimensional thin MoS2nanosheets show extraordinary properties such as the presence of a direct bandgap, magnetism, superconductivity and ferroelectricity. Over the past few years, solution-processed exfoliation methods of layered materials have been extensively studied; most of the exfoliation processes employ organic solvents or use surfactants as well as other functionalization agents. Although pure water is considered as an ideal solvent, however, it is generally believed stable dispersions of water could not be achieved due to poor solubility MoS2 in water. Thus, there are very limited studies for developing of water based MoS2 dispersions. Here we introduce a facile, green and reliable exfoliation method for producing water-dispersible MoS2 nanosheet without surfactant. Pure water was used as a solvent and this exfoliation process was achieved by thinning the bulk MoS2 by mechanical force between sandpapers and dispersing it through probe sonication in water. The exfoliated single or few-layered MoS2 nanosheets were characterized by TEM and SEM images. The lateral dimensions of the nanosheets were around 500 nm to 5 µm, the same range as obtained in the organic solvents as reported. Zeta potential measurements indicated that electrical charges may be responsible for the stabilization of the dispersions. Overall, it is concluded that with this exfoliation strategy, water can be used as a useful dispersible solvent for MoS2 nanosheets. Although the stability of the dispersions may not be as high as in organic solvents, the present method could be employed for a number of applications where the dispersions can be produced on site and organic solvents are not desirable.

The Effect of Milling Time on the Microstructural Characteristics and Strengthening Mechanisms of NiMo-SiC Alloys Prepared via Powder Metallurgy.

A new generation of alloys, which rely on a combination of various strengthening mechanisms, has been developed for application in molten salt nuclear reactors. In the current study, a battery of dispersion and precipitation-strengthened (DPS) NiMo-based alloys containing varying amounts of SiC (0.5-2.5 wt %) were prepared from Ni-Mo-SiC powder mixture via a mechanical alloying (MA) route followed by spark plasma sintering (SPS) and rapid cooling. Neutron Powder Diffraction (NPD), Electron Back Scattering Diffraction (EBSD), and Transmission Electron Microscopy (TEM) were employed in the characterization of the microstructural properties of these in-house prepared NiMo-SiC DPS alloys. The study showed that uniformly-dispersed SiC particles provide dispersion strengthening, the precipitation of nano-scale Ni3Si particles provides precipitation strengthening, and the solid-solution of Mo in the Ni matrix provides solid-solution strengthening. It was further shown that the milling time has significant effects on the microstructural characteristics of these alloys. Increased milling time seems to limit the grain growth of the NiMo matrix by producing well-dispersed Mo2C particles during sintering. The amount of grain boundaries greatly increases the Hall-Petch strengthening, resulting in significantly higher strength in the case of 48-h-milled NiMo-SiC DPS alloys compared with the 8-h-milled alloys. However, it was also shown that the total elongation is considerably reduced in the 48-h-milled NiMo-SiC DPS alloy due to high porosity. The porosity is a result of cold welding of the powder mixture during the extended milling process.

Collection and storage of urine specimens for measurement of urolithiasis risk factors.

OBJECTIVE: To evaluate how different methods for storage and preservation of urine samples affected the outcome of analysis of risk factors for stone formation. METHODS: Spot urine samples were collected from 21 healthy volunteers. Each fresh urine sample was divided into ten 10-mL aliquots: 2 without preservative, 2 with thymol, 2 with toluene, 2 with hydrochloric acid (HCl), and 2 with sodium azide. One sample of each pair was stored at 4 °C and the other at room temperature. The concentrations of calcium, magnesium, sodium, phosphate, urate, oxalate, citrate, and pH in each urine sample were analyzed immediately after collection (0 hour) and after 24 and 48 hours. RESULTS: There were no significant differences in calcium, oxalate, magnesium, phosphate, sodium, urate or pH (without acidification) between samples with different preservation methods (P >.05). Urinary citrate, however, was significantly lower in the urine collected with HCl than when other preservatives were used, both at room temperature and at 4 °C. Urine pH was significantly higher after 48 hours than after 24 hours, whether the samples were stored at room temperature or at 4 °C. CONCLUSION: Antibacterial preservatives (eg, thymol or toluene) can be recommended as preservatives for 24-hour urine collections. Ideally, the samples should be stored at 4 °C. When HCl is used as a preservative, it seems essential to neutralize the samples before analysis. This is particularly obvious with the chromatographic method used for analysis of citrate that was used in this study.

Safety and efficacy of minimally invasive percutaneous nephrolithotomy in treatment of calculi in horseshoe kidneys.

OBJECTIVE: To evaluate the safety and efficacy of minimally invasive percutaneous nephrolithotomy (MPCNL) in horseshoe kidneys (HKs) with calculi. MATERIALS AND METHODS: From 2006 to 2012, 35 renal units in 32 patients with calculi in HKs underwent MPCNL. Patients and stone characteristics, stone-free rates (SFR), and complications were evaluated. The composition of the stones obtained from operation was also analyzed by infrared spectroscopy. RESULTS: The average age of patients was 38.2±7.3 years (range 14-72). The mean stone burden was 657±510.9 mm(2) (range 134.7-2460.1). The mean operative time was 93.4±17.6 minutes (53-152). The most popular access site was upper pole access (35/42, 83.3%). The SFR after initial MPCNL was 82.9% (29/35 renal units). Second-stage MPCNL was performed in 5 renal units, with a 91.4% (32/35 renal units) final SFR. Minor complications (Clavien grades I and II) were seen in six patients, and urosepsis requiring intensive care unit management in one (Clavien grade IVa). All were treated successfully. CONCLUSION: MPCNL is a safe and effective treatment modality in HK stones with acceptable results, which was compatible to a normal anatomy kidney. However, further studies with a larger sample size are required.

The characteristics of the stone and urine composition in Chinese stone formers: primary report of a single-center results.

OBJECTIVE: To assess urine composition in Chinese patients with urolithiasis. METHODS: Five hundred seven Chinese patients with urolithiasis from our center in southern China were included in this study. Analysis of stone composition was performed using infrared spectrometry. From all patients, 24-hour urine samples were collected for analysis of urinary variables. Some ion activity product risk indices were also calculated. RESULTS: The major stone constituents in the 507 analyzed stones were as follows: calcium oxalate (78.3%), infection stone components (14.6%), uric acid (3.6%), and calcium phosphate (3.4%). Only 1 stone was composed of cystine (0.2%). Of all patients, 504 (99.4%) had 1 or several urinary metabolic abnormalities. Hypocitraturia was recorded in 93.9%, high sodium excretion in 58.6%, small urine volume in 45.6%, hyperoxaluria in 31.0%, hypercalciuria in 26.0%, hyperuricosuria in 19.3%, and hyperphosphaturia in 2.8%. Moreover, high sodium excretion was more frequent in men than women (59.2% vs 49.3%, P = .027), whereas hypercalciuria was more common in women (34.5% vs 20.4%, P <.001). High levels of urine sodium (187.7 ± 86.9 vs 179.8 ± 107.7 mmol/24h, P = .038) and phosphate (18.26 ± 8.36 vs 15.69 ± 11.14 mmol/24h, P <.001) were found in men than in women. Infection stones were significantly (P <.004) more common in women. Compared with noninfection stone formers, the occurrence of hypomagnesuria (P = .040) was more common in patients with infection stones. CONCLUSION: The results of urinary risk factors for stone formation in this study might serve as a basis for design of recurrence prevention. It is of interest to note that some of the demonstrated abnormalities differ from that in reports from other countries.

Expression of PARP-1 and its active polymer PAR in prostate cancer and benign prostatic hyperplasia in Chinese patients.

BACKGROUND AND AIMS: Aberrant expression of PARP-1 has been reported in various human malignancies and was involved in the progression and metastasis of cancers. However, little is known about PARP-1 expression in prostate cancer (PCa). This study aimed to investigate the expression of PARP-1 and its active polymer poly(ADP-ribose) (PAR) in PCa and benign prostatic hyperplasia (BPH) tissues from Chinese patients. METHODS: The expression of PARP-1 and PAR in PCa and benign prostate hyperplasia tissues was assessed by immunohistochemistry in 78 PCa patients and 49 BPH patients. The relationship between the expression of PARP-1 or PAR and clinicopathological parameters in PCa patients was also analyzed. RESULTS: Both the positive and strong positive expression rates of PARP-1 in PCa tissues were significantly higher than those in BPH tissues. Although spearman correlations analysis showed the over-expression of PARP-1 and PAR in PCa tissues was not correlated with age, serum PSA level and Gleason scores (GS), an increasing trend was observed between over-expression of PARP-1 or PAR and the PSA levels (TPSA >20 vs TPSA ≤20) or GS grade (GS ≥8 vs GS ≤6). CONCLUSION: PARP-1 and PAR expression is markedly elevated in PCa than that in BPH tissues, which may implicate that PARP-1 and PAR are involved in the development of PCa, and the possible expansion in the use of poly(ADP-ribose) polymerase inhibitors for targeting therapy of PCa in select patients alone or combined with chemotherapy or radiation.