Trends in socioeconomic inequality in e-cigarette use among adolescents in South Korea.

INTRODUCTION: The global rise in e-cigarette use among adolescents is alarming, with associated socioeconomic inequalities posing potential public health risks. This study examined trends in the socioeconomic inequality in e-cigarette use among South Korean adolescents to inform future regulatory directions. METHODS: Socioeconomic inequalities in e-cigarette use among Korean adolescents were assessed using data from the Korea Youth Risk Behavior Web-based Survey (KYRBS) from 2011 to 2023. The Concentration Index, a well-established method for measuring health inequalities, was employed. Additionally, this study investigated how the smoking behaviors of family members and friends influence socioeconomic inequality in e-cigarette use among Korean adolescents, using a decomposition analysis. RESULTS: The Concentration Index values showed a clear, fluctuating downward trend over 13 years, from -0.12 (95% CI: -0.13 - -0.10) in 2011 to -0.24 (95% CI: -0.26 - -0.21) in 2023. Decomposition analysis revealed that smoking among peer groups, including friends and siblings, was the primary contributor to socioeconomic inequality in e-cigarette use, followed by maternal smoking. CONCLUSIONS: Socioeconomic inequalities in adolescent e-cigarette use in South Korea are widening, particularly among low socioeconomic status groups. The impact of peer groups on socioeconomic inequalities in e-cigarette use among adolescents is concerning.

The number and position of unsaturated bonds in aliphatic aldehydes affect meat flavorings system: Insights on initial Maillard reaction stage and meat flavor formation from thiazolidine derivatives.

Nonanal, (E)-2-nonenal, (E,E)-2,4-nonadienal, and (E,Z)-2,6-nonadienal were used to study the effect of number and position of the unsaturated bond in aliphatic aldehydes on meat flavorings. Cysteine-Amadori and thiazolidine derivatives were synthesized, identified by UPLC-TOF/MS and NMR, and quantitatively by UPLC-MS/MS. The polyunsaturated aldehydes exhibited higher inhibition than monounsaturated aldehydes, and monounsaturated aldehydes exhibited higher inhibition than saturated aldehydes, mainly manifested by the inhibition of the cysteine-Amadori formation and acceleration of the thiazolidine derivatives formation. The effect of unsaturated bonds position in aliphatic aldehydes on the initial Maillard reaction stage was similar. The cysteine played an important role in catalyzing the reaction of aliphatic aldehydes. A total of 109 volatile compounds derived by heating prepared thiazolidine derivatives degradation were detected by GC-MS. Formation pathways of volatile compounds were proposed by retro-aldol, oxidation, etc. Particularly, a route to form thiazole by the decarboxylation reaction of thiazolidine derivatives which derivatives from formaldehyde reacting with cysteine was proposed.

All-In-One OsciDrop Digital PCR System for Automated and Highly Multiplexed Molecular Diagnostics.

Digital PCR (dPCR) holds immense potential for precisely detecting nucleic acid markers essential for personalized medicine. However, its broader application is hindered by high consumable costs, complex procedures, and restricted multiplexing capabilities. To address these challenges, an all-in-one dPCR system is introduced that eliminates the need for microfabricated chips, offering fully automated operations and enhanced multiplexing capabilities. Using this innovative oscillation-induced droplet generation technique, OsciDrop, this system supports a comprehensive dPCR workflow, including precise liquid handling, pipette-based droplet printing, in situ thermocycling, multicolor fluorescence imaging, and machine learning-driven analysis. The system's reliability is demonstrated by quantifying reference materials and evaluating HER2 copy number variation in breast cancer. Its multiplexing capability is showcased with a quadruplex dPCR assay that detects key EGFR mutations, including 19Del, L858R, and T790M in lung cancer. Moreover, the digital stepwise melting analysis (dSMA) technique is introduced, enabling high-multiplex profiling of seven major EGFR variants spanning 35 subtypes. This innovative dPCR system presents a cost-effective and versatile alternative, overcoming existing limitations and paving the way for transformative advances in precision diagnostics.

Association between exposure to tobacco information through mass media, smoking households and secondhand smoke exposure in adolescents: Survey data from South Korea.

INTRODUCTION: To explore the current situation of exposure of Korean adolescents to secondhand smoke (SHS) in households our study aimed to determine the relationship between family member smoking status, exposure to tobacco information through mass media, and household SHS exposure. METHODS: The present study uses pooled data from the Korean adolescent health behavior online survey conducted in 2015, 2018 and 2021, with 157944 participants. The regression models were used to explore the association between the smoking status of households, and exposure to tobacco information through mass media, and household SHS exposure in adolescents, controlling for potential confounding factors. RESULTS: SHS exposure duration of Korean adolescents in households was 0.88 days per week. The households with smokers including the father (ß=1.087; 95% CI: 1.0-1.126), mother (ß=1.461; 95% CI: 1.379- 1.543), siblings (ß=0.545; 95% CI: 0.493-0.597), grandparents (ß=0.224; 95% CI: 0.174-0.272), and other relatives (ß=0.170; 95% CI: 0.126-0.214), showed a positive association with SHS exposure in adolescents within the household. At the same time, information about anti-smoking ads on television (ß= -0.042; 95% CI: -0.069 - -0.015) and public transportation (ß= -0.031; 95% CI: -0.054 - -0.010), showed a negative association with SHS exposure in adolescents. However, broadcasts, online, and newspaper non-smoking ads were not associated with SHS exposure (p>0.05). In addition, regression models revealed that exposure to cigarette advertising in magazines (ß=0.131; 95% CI: 0.097-0.166), networks (ß=0.151; 95% CI: 0.127-0.175), convenience stores (ß=0.061; 95% CI: 0.035-0.087), and supermarkets (ß=0.133; 95% CI: 0.108-0.158) is associated with SHS exposure in adolescents. Finally, our study showed stronger ties between SHS exposure, family smoking, and tobacco ads in girls. The link between maternal smoking, supermarket ads, and adolescent SHS exposure intensified in 2021 compared to 2015. CONCLUSIONS: Family and media were identified as potential factors associated with SHS exposure in adolescents. Therefore, publicity and education regarding household SHS hazards, and smoking bans in media, can be helpful in protecting adolescents from SHS.

Corrigendum: Association between exposure to tobacco information through mass media, smoking households and secondhand smoke exposure in adolescents: Survey data from South Korea.

[This corrects the article DOI: 10.18332/tid/175705.].

The number and position of unsaturated bonds in aliphatic aldehydes affect the cysteine-glucose Maillard reaction: Formation mechanism and comparison of volatile compounds.

Nonanal, (E)-2-nonenal, (E,E)-2,4-nonadienal, and (E,Z)-2,6-nonadienal were used to reveal the effect of the number and position of unsaturated bond in aliphatic aldehydes on Maillard reaction for the generation of 88 stewed meat-like volatile compounds. The results showed that (E,E)-2,4-nonadienal and (E,Z)-2,6-nonadienal exhibited greater inhibition of the cysteine reaction with glucose than nonanal and (E)-2-nonenal. However, the positions of the unsaturated bonds in aliphatic aldehydes in the Maillard reaction stage were similar. A carbohydrate module labeling approach was used to present the formation pathways of 34 volatile compounds derived from the Maillard reaction with aliphatic aldehyde systems. The number and position of unsaturated bonds in aliphatic aldehydes generate multiple pathways of flavor compound formation. 2-Propylfuran and (E)-2-(2-pentenyl)furan resulted from aliphatic aldehydes. 5-Butyldihydro-2(3H)-furanone and 2-methylthiophene were produced from the Maillard reaction. 2-Furanmethanol, 2-thiophenecarboxaldehyde, and 5-methyl-2-thiophenecarboxaldehyde were derived from the interaction of aliphatic aldehydes and the Maillard reaction. In Particular, the addition of aliphatic aldehydes changed the formation pathway of 2-propylthiophene, thieno[3,2-b]thiophene, and 2,5-thiophenedicarboxaldehyde. Heatmap and PLS-DA analysis could discriminate volatile compound compositions of the five systems and screen the marker compounds differentiating volatile compounds.

A Novel Approach for Apple Freshness Prediction Based on Gas Sensor Array and Optimized Neural Network.

Apple is an important cash crop in China, and the prediction of its freshness can effectively reduce its storage risk and avoid economic loss. The change in the concentration of odor information such as ethylene, carbon dioxide, and ethanol emitted during apple storage is an important feature to characterize the freshness of apples. In order to accurately predict the freshness level of apples, an electronic nose system based on a gas sensor array and wireless transmission module is designed, and a neural network prediction model using an improved Sparrow Search Algorithm (SSA) based on chaotic sequence (Tent) to optimize Back Propagation (BP) is proposed. The odor information emitted by apples is studied to complete an apple freshness prediction. Furthermore, by fitting the relationship between the prediction coefficient and the input vector, the accuracy benchmark of the prediction model is set, which further improves the prediction accuracy of apple odor information. Compared with the traditional prediction method, the system has the characteristics of simple operation, low cost, reliable results, mobile portability, and it avoids the damage to apples in the process of freshness prediction to realize non-destructive testing.

Approximate Bayesian computation design for phase I clinical trials.

In the development of new cancer treatment, an essential step is to determine the maximum tolerated dose in a phase I clinical trial. In general, phase I trial designs can be classified as either model-based or algorithm-based approaches. Model-based phase I designs are typically more efficient by using all observed data, while there is a potential risk of model misspecification that may lead to unreliable dose assignment and incorrect maximum tolerated dose identification. In contrast, most of the algorithm-based designs are less efficient in using cumulative information, because they tend to focus on the observed data in the neighborhood of the current dose level for dose movement. To use the data more efficiently yet without any model assumption, we propose a novel approximate Bayesian computation approach to phase I trial design. Not only is the approximate Bayesian computation design free of any dose-toxicity curve assumption, but it can also aggregate all the available information accrued in the trial for dose assignment. Extensive simulation studies demonstrate its robustness and efficiency compared with other phase I trial designs. We apply the approximate Bayesian computation design to the MEK inhibitor selumetinib trial to demonstrate its satisfactory performance. The proposed design can be a useful addition to the family of phase I clinical trial designs due to its simplicity, efficiency and robustness.

The interaction between self - assembling peptides and emodin and the controlled release of emodin from in-situ hydrogel.

Ion-complementary self-assembling peptides have potential in delivering hydrophobic drugs. This study involved two self-assembling peptides, RADA16-I and RVDV16-I, of which RVDV16-I was a novel self-assembling peptide with different hydrophobic side chains designed from RADA16-I. The purpose of this study was to observe the interaction between different self-assembling peptides and emodin through fluorescence spectrophotometry, CD, SEM and AFM; to construct a preliminary suspension in-situ hydrogel delivery system for emodin with the self-assembling peptides; and to investigate the drug-loading and drug-releasing properties of the self-assembling peptides on emodin. The results showed that both peptides can interact with emodin and the interaction was dominated by hydrophobic interaction. The aqueous solutions of both self-assembling peptides can form relatively stable suspensions with emodin under mechanical stirring, and the suspension can form in-situ hydrogel under physiological condition. In vitro release of emodin from the hydrogels showed a manner of sustained release to some extent. Cell viability studies showed inherent proliferation inhibiting effects of emodin on tumor cells was maintained or enhanced through the in-situ hydrogels. The self-assembling peptides RADA16-I and RVDV16-I had showed promising drug-loading and drug-releasing performance for hydrophobic drugs. It is reasonable to exploit self-assembling peptides as drug carriers for their great potential to improve delivery of hydrophobic drugs.

Assembled Step Emulsification Device for Multiplex Droplet Digital Polymerase Chain Reaction.

Digital PCR is a powerful method for absolute nucleic acid quantification with unprecedented accuracy and precision. To promote the wider use and application of digital PCR, several major challenges still exist, including reduction of cost, integration of the instrumental platform, and simplification of operations. This paper describes a reusable microfluidic device that generates nanoliter droplet arrays based on step emulsification for the on-chip multiplex digital PCR of eight samples simultaneously. The device contains two glass plates that can be quickly assembled with prefilled mineral oil. Droplets are simply generated through the arrays of step emulsification nozzles driven by a single pressure controller and are self-assembled into monolayer droplet arrays in U-shaped chambers. The use of mineral oil eliminates bubble generation; thus, no overpressure is required during thermocycling. Moreover, the device can be reused many times after disassembly and a brief cleaning procedure, which significantly reduces the cost of the device per dPCR assays. The device was able to detect template DNA at concentrations as low as 10 copies/µL with a dynamic range of approximately 4 logs. We applied this device in the quantitative assessment of HER2 copy number variation, which is important for targeted therapy and prognosis of breast cancer. The performance was validated by 16 clinical samples, obtaining similar results to commercial digital PCR. We envision that this low-cost, reusable, and user-friendly device can be broadly used in various applications.

Meat flavor generation from different composition patterns of initial Maillard stage intermediates formed in heated cysteine-xylose-glycine reaction systems.

Volatile compounds formed in model reactions involving synthesized initial Maillard intermediates Gly-Amadori and [13C5]-2-threityl-thiazolidine-4-carboxylic acids ([13C5]-TTCA) in different molar ratios and free cysteine and glycine were investigated by solid-phase microextraction/gas chromatography-mass spectrometry and gas chromatography-olfactometry. The 1:1 ratio composition pattern provided the highest yields of all the sulfur-containing compounds, the potent meaty flavors or their 13C-labeled/unlabeled fractions, indicating a moderate level of glycine relative to cysteine was optimum for maximally yielding meaty flavors in complex meat-like Maillard systems containing cysteine as well as glycine. In addition, the 1:1 ratio composition led to formation of 13C-labeled molecules of some key meaty flavors e.g. 2-furanthiol representing over 70%, indicating TTCA/glycine reaction was better than Gly-Amadori/cysteine to yield meaty flavors. Formation pathways of twenty-nine flavors were elucidated based on the detected isotope distribution patterns. In particular, 2-methyltetrahydrothiophen-3-one, 3-thiophenethiol, 2-ethylthiophene, 2,5-dimethylthiophene, and 5-methylthiophene-2-carboxaldehyde involved a new formation pathway. Thiophene-2-carboxaldehyde and 2-methylthieno[3,2-b]thiophene showed two formation pathways.

Hyphobacterium indicum sp. nov., isolated from deep seawater, and emended description of the genus Hyphobacterium.

A novel aerobic, Gram-stain-negative bacterium, designated strain 2ED5T, was isolated from a deep seawater sample in the north-west Indian Ocean. Cells of the strain were oval- to rod-shaped, and motile by a polar flagellum or sessile by a prostheca. The strain formed creamy white colonies on 2216E marine agar plates. It grew at 10-40 °C (optimum 28 °C) and pH 5.0-8.0 (optimum pH 6.0-7.0). The strain required 1-6 % (w/v) NaCl for growth and grew optimally in the presence of 2-3 % NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain 2ED5T was affiliated with the genus Hyphobacterium in the family Hyphomonadaceae of the class Alphaproteobacteria, sharing 95.1 % similarity at the 16S rRNA gene sequence level with the type strain of Hyphobacterium vulgare, the only species in the genus Hyphobacterium. The major fatty acids of the strain were C18 : 1ω7c and iso-C17 : 1ω9c, and the polar lipids included monoglycosyl diglyceride, sulfoquinovosyl diacylglycerol, glucuronopyranosyl diglyceride, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and an unidentified glycolipid. The strain contained ubiquinone Q-10 as the predominant respiratory quinone. The G+C content of the genomic DNA of the strain was 60.9 mol%. Based on the results of this polyphasic analysis, strain 2ED5T represents a novel species in the genus Hyphobacterium, for which the name Hyphobacterium indicum sp. nov. is proposed. The type strain is 2ED5T (=CGMCC 1.16466T=JCM 32612T).

Aroma Compounds in Chicken Broths of Beijing Youji and Commercial Broilers.

The unique flavor of Beijing Youji (BJY) chicken broth compared with that of commercial broilers (CB) was investigated by solvent-assisted flavor evaporation combined with AEDA/GC-O (aroma extract dilution analysis of gas chromatography-olfactometry), quantitation, and aroma recombination. A total of 71 odorants with almost the same major odorants (≥10 ng/g broth) were found by GC-O in both BJY and CB broths. However, BJY broth had thirty-two more extra odorants than CB broth, indicating the rich fragrance of the former. Aroma recombination and omission experiments demonstrated that 21 versus 17 odorants (with OAV ≥ 1) contributed significantly to BJY and CB broth aromas, respectively. Those key odorants mainly included sulfur-containing compounds and aliphatic aldehydes, such as 2-methyl-3-furanthiol, 3-(methylthio)propanal, ( E, E)-2,4-decadienal, etc. Furthermore, composition analysis of the meat suggested that the better flavor, with rather more odorants, of BJY broth is probably due to higher contents of polyunsaturated fatty acids and water-soluble flavor precursor, including ribose, cysteine, thiamine, etc., present in the BJY meat.

A microfluidic surface-enhanced Raman spectroscopy approach for assessing the particle number effect of AgNPs on cytotoxicity.

Silver nanoparticles (Ag NPs) have well-known antibacterial properties and are widely applied in various medical products and general commodities. Although many studies have addressed the toxicity of Ag NPs to mammalian cells, the direct relationship between the number of Ag NPs in living cells and the corresponding cell toxicity has not yet been explicitly demonstrated. In this work, a simple and reusable microfluidic device composed of a quartz cover slip and a glass plate with etched micro-channel and micro-wells was employed for separating and trapping single living cells. The device was silanized to render the surface hydrophobic. For simplicity, HeLa cells as the model cancer cells were used in the study, which were pipette-loaded into an array of micro wells based on dead-end filling. Surface enhanced Raman spectroscopy (SERS) was then employed to examine the living cancer cells and assessed number and distribution of Ag NPs in the cells. Combined with the cell viability assay, we therefore correlated the number of Ag NPs in the cell with the toxicity to the cell directly.

Virgibacillus indicus sp. nov. and Virgibacillus profundi sp. nov, two moderately halophilic bacteria isolated from marine sediment by using microfluidic streak plates.

Three Gram-variable, moderately halophilic, motile, endospore-forming rods, designated P2-C2T, P3-H5T and P3-B8, were isolated from marine sediment of the Southwest Indian Ocean by using the microfluidic streak plate method. Phylogeny based on 16S rRNA gene sequences showed that strains P2-C2T and P3-H5T formed a robust cluster within the genus Virgibacillus and exhibited 16S rRNA gene similarity levels of 95.3-96.8 and 94.9-96.3 % to the type strains of Virgibacillus species, respectively. The 16S rRNA gene similarity between P2-C2T and P3-H5T was 97.6 %. Strain P3-B8 has an identical 16S rRNA gene sequence to strain P3-H5T. For all the novel strains, the predominant cellular fatty acids were anteiso-C15 : 0 and anteiso-C17 : 0, the main menaquinone was MK-7, and the polar lipid profiles contained diphosphatidylglycerol and phosphatidylglycerol. The genomic DNA G+C contents of strains P2-C2T, P3-H5T and P3-B8 were 38.3, 37.3 and 37.5 mol%, respectively. Combined data from phenotypic and genotypic studies demonstrated that strains P2-C2T and P3-H5T/P3-B8 are representatives of two different novel species of the genus Virgibacillus, for which the name Virgibacillus indicus sp. nov. and Virgibacillusprofundi are proposed. The type strains are P2-C2T (=CGMCC 1.16138T=NBRC 113014T) and P3-H5T (=CGMCC 1.16139T=NBRC 113015T).

High-Internal-Phase Emulsion Tailoring Polymer Amphiphilicity towards an Efficient NIR-Sensitive Bacteria Filter.

Emulsions having a high internal-phase volume fraction­termed as HIPEs for high internal phase emulsions­are in high demand as templates for functional macroporous materials. Designing molecular surfactants with appropriate amphiphilicity plays a critical role in the HIPE preparation. In this study, successful tailoring of the amphiphilicity of the originally hydrophobic block co-polymer of polystyrene-b-polyvinylpyridine (PS-b-P4VP) is reported. In combination with trifluoroacetic acid, less than 5 wt% of the polymer-CF3COOH system is feasible as a surfactant for HIPE preparation; this is lower than the amounts typically needed for commonly used commercial surfactants. Using the HIPEs as templates, well-defined closed- and open-cell macroporous triacrylate-based monoliths are fabricated simply through the adjustment of the ratio of the water phase to oil phase. After coating the resulting macroporous material with polypyrrole nanoparticles, the system can be exploited as an NIR-sensitive filter for bacteria; it not only excludes oversized bacteria, but it also kills the bacteria with the help of NIR-induced heat.

Iron-catalyzed radical oxidative coupling reaction of aryl olefins with 1,3-dithiane.

An alternative method to an iron-catalyzed radical oxidative cross-coupling reaction followed by 2-chloro-1,3-dithiane and aryl olefins for the synthesis of ß-chloro substituent 1,3-dithiane products is presented. The described method has the advantage of mildness of the reaction conditions and tolerates a variety of functional groups. Preliminary mechanistic studies have confirmed the first example of a coupling of 1,3-dithiane with unactivated alkenes that proceeds via an iron-catalyzed oxidative radical intermediate along the reaction pathway.

Forced assembly of water-dispersible carbon nanotubes trapped in paper for cheap gas sensors.

A versatile and readily scalable approach to fabricate a cheap and sensitive paper gas sensor is described. Chemically acidified single-walled carbon nanotubes are assembled in paper, forming continuous sensing arrays with a low detection limit and high detection selectivity for ammonia gas.

Theoretical design and analysis of multivolume digital assays with wide dynamic range validated experimentally with microfluidic digital PCR.

This paper presents a protocol using theoretical methods and free software to design and analyze multivolume digital PCR (MV digital PCR) devices; the theory and software are also applicable to design and analysis of dilution series in digital PCR. MV digital PCR minimizes the total number of wells required for "digital" (single molecule) measurements while maintaining high dynamic range and high resolution. In some examples, multivolume designs with fewer than 200 total wells are predicted to provide dynamic range with 5-fold resolution similar to that of single-volume designs requiring 12,000 wells. Mathematical techniques were utilized and expanded to maximize the information obtained from each experiment and to quantify performance of devices and were experimentally validated using the SlipChip platform. MV digital PCR was demonstrated to perform reliably, and results from wells of different volumes agreed with one another. No artifacts due to different surface-to-volume ratios were observed, and single molecule amplification in volumes ranging from 1 to 125 nL was self-consistent. The device presented here was designed to meet the testing requirements for measuring clinically relevant levels of HIV viral load at the point-of-care (in plasma, <500 molecules/mL to >1,000,000 molecules/mL), and the predicted resolution and dynamic range was experimentally validated using a control sequence of DNA. This approach simplifies digital PCR experiments, saves space, and thus enables multiplexing using separate areas for each sample on one chip, and facilitates the development of new high-performance diagnostic tools for resource-limited applications. The theory and software presented here are general and are applicable to designing and analyzing other digital analytical platforms including digital immunoassays and digital bacterial analysis. It is not limited to SlipChip and could also be useful for the design of systems on platforms including valve-based and droplet-based platforms. In a separate publication by Shen et al. (J. Am. Chem. Soc., 2011, DOI: 10.1021/ja2060116), this approach is used to design and test digital RT-PCR devices for quantifying RNA.

Multiplexed quantification of nucleic acids with large dynamic range using multivolume digital RT-PCR on a rotational SlipChip tested with HIV and hepatitis C viral load.

In this paper, we are working toward a problem of great importance to global health: determination of viral HIV and hepatitis C (HCV) loads under point-of-care and resource limited settings. While antiretroviral treatments are becoming widely available, viral load must be evaluated at regular intervals to prevent the spread of drug resistance and requires a quantitative measurement of RNA concentration over a wide dynamic range (from 50 up to 10(6) molecules/mL for HIV and up to 10(8) molecules/mL for HCV). "Digital" single molecule measurements are attractive for quantification, but the dynamic range of such systems is typically limited or requires excessive numbers of compartments. Here we designed and tested two microfluidic rotational SlipChips to perform multivolume digital RT-PCR (MV digital RT-PCR) experiments with large and tunable dynamic range. These designs were characterized using synthetic control RNA and validated with HIV viral RNA and HCV control viral RNA. The first design contained 160 wells of each of four volumes (125 nL, 25 nL, 5 nL, and 1 nL) to achieve a dynamic range of 5.2 × 10(2) to 4.0 × 10(6) molecules/mL at 3-fold resolution. The second design tested the flexibility of this approach, and further expanded it to allow for multiplexing while maintaining a large dynamic range by adding additional wells with volumes of 0.2 nL and 625 nL and dividing the SlipChip into five regions to analyze five samples each at a dynamic range of 1.8 × 10(3) to 1.2 × 10(7) molecules/mL at 3-fold resolution. No evidence of cross-contamination was observed. The multiplexed SlipChip can be used to analyze a single sample at a dynamic range of 1.7 × 10(2) to 2.0 × 10(7) molecules/mL at 3-fold resolution with limit of detection of 40 molecules/mL. HIV viral RNA purified from clinical samples were tested on the SlipChip, and viral load results were self-consistent and in good agreement with results determined using the Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 Test. With further validation, this SlipChip should become useful to precisely quantify viral HIV and HCV RNA for high-performance diagnostics in resource-limited settings. These microfluidic designs should also be valuable for other diagnostic and research applications, including detecting rare cells and rare mutations, prenatal diagnostics, monitoring residual disease, and quantifying copy number variation and gene expression patterns. The theory for the design and analysis of multivolume digital PCR experiments is presented in other work by Kreutz et al.