Buoyancy-Driven Micro/-Nanomotors: From Fundamentals to Applications.

The progression of self-powered micro/-nanomotors (MNMs) has rapidly evolved over the past few decades, showing applications in various fields such as nanotechnology, biomedical engineering, microfluidics, environmental science, and energy harvesting. Miniaturized MNMs transduce chemical/biochemical energies into mechanical motion for navigating through complex fluidic environments with directional control via external forces fields such as magnetic, photonic, and electric stimuli. Among various propulsion mechanisms, buoyancy-driven MNMs have received noteworthy recognition due to their simplicity, efficiency, and versatility. Buoyancy force-driven motors harness the principles of density variation-mediated force to overcome fluidic resistance to navigate through complex environments. Restricting the propulsion in one direction helps to control directional movement, making it more efficient in isotropic solutions. The changes in pH, ionic strength, chemical concentration, solute gradients, or the presence of specific molecules can influence the motion of buoyancy-driven MNMs as evidenced by earlier reports. This review aims to provide a fundamental and detailed analysis of the current state-of-the-art in buoyancy-driven MNMs, aiming to inspire further research and innovation in this promising field.

Effect of Target Power on Microstructure, Tribological Performance and Biocompatibility of Magnetron Sputtered Amorphous Carbon Coatings.

The tribological properties and preosteoblast behavior of an RF magnetron-sputtered amorphous carbon coating on a Si (100) substrate were evaluated. The graphite target power was varied from 200 to 500 W to obtain various coating structures. The amorphous nature of the coatings was confirmed via Raman analysis. The contact angle also increased from 58º to 103º, which confirmed the transformation of the a-C surface from a hydrophilic to hydrophobic nature with an increasing graphite target power. A minimum wear rate of about 4.73 × 10-8 mm3/N*mm was obtained for an a-C coating deposited at a 300 W target power. The 300 W and 400 W target power coatings possessed good tribological properties, and the 500 W coating possessed better cell viability and adhesion on the substrate. The results suggest that the microstructure, wettability, tribological behavior and biocompatibility of the a-C coating were highly dependent on the target power of the graphite. A Finite Element Analysis (FEA) showed a considerable increase in the Von Mises stress as the mesh size decreased. Considering both the cell viability and tribological properties, the 400 W target power coating was identified to have the best tribological property as well as biocompatibility.

Investigation on Physico Chemical and X-ray Shielding Performance of Zinc Doped Nano-WO3 Epoxy Composite for Light Weight Lead Free Aprons.

This report addresses a way to reduce the usage of highly toxic lead in diagnostic X-ray shielding by developing a cost-effective, eco-friendly nano-tungsten trioxide (WO3) epoxy composite for low-weight aprons. Zinc (Zn)-doped WO3 nanoparticles of 20 to 400 nm were synthesized by an inexpensive and scalable chemical acid-precipitation method. The prepared nanoparticles were subjected to X-ray diffraction, Raman spectroscopy, UV-visible spectroscopy, photoluminescence, high-resolution-transmission electron microscope, scanning electron microscope, and the results showed that doping plays a critical role in influencing the physico-chemical properties. The prepared nanoparticles were used as shielding material in this study, which were dispersed in a non-water soluble durable epoxy resin polymer matrix and the dispersed materials were coated over a rexine cloth using the drop-casting method. The X-ray shielding performance was evaluated by estimating the linear attenuation coefficient (µ), mass attenuation coefficient (µm), half value layer (HVL), and X-ray percentage of attenuation. Overall, an improvement in X-ray attenuation in the range of 40-100 kVp was observed for the undoped WO3 nanoparticles and Zn-doped WO3 nanoparticles, which was nearly equal to lead oxide-based aprons (reference material). At 40 kVp, the percentage of attenuation of 2% Zn doped WO3 was 97% which was better than that of other prepared aprons. This study proves that 2% Zn doped WO3 epoxy composite yields a better particle size distribution, µm, and lower HVL value and hence it can be a convenient lead free X-ray shielding apron.

N-substituted CQDs impregnated by Fe3O4 heterostructure: Bifunctional catalyst for electro-catalytic and photo-catalytic detection of an environmental hazardous organic pollutant.

ortho-Nitroaniline (o-NA) compounds are deemed to be a strongly toxic pollutant in nature and potentially carcinogenic; however, they are frequently utilized to synthesize dyes, pesticides, medicines, fungicides, pigments, and other organic chemicals. Their detection in an aqueous medium is fundamentally required to avoid the potential hazardous being created by these compounds. In this study, a novel sensor based on an Iron oxide (Fe3O4) containing highly dispersed nitrogen-doped carbon quantum dots (N-CQDs@Fe3O4 NFs) was demonstrated for the electrochemical detection of o-NA using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. N-CQDs@Fe3O4 NFs were synthesized by hydrothermal method and studied by various analytical and spectroscopy techniques, which collectively reveal that the as-prepared composite has superior physical and chemical properties. The DPV study indicated that the o-NA sensor had a good limit of detection, linear range, and sensitivity in the range of 1.2 nm, 0.03-386.84 µM, and 36.5575 µA µM-1 cm-2, respectively, along with the sensor showed superior sensitivity when compared to the previously reported modified electrodes. Further, N-CQD/Fe3O4 NFs worked as heterogeneous catalysts for the photocatalytic reduction of o-NA to o-phenylenediamine (o-PD) in an aqueous medium. The reaction was examined under UV-Visible spectroscopy, and the complete photocatalytic reduction was observed for the N-CQD/Fe3O4 NFs in about 6 min with 96% as compared to other control samples; thus, authenticating the superiority of the synthesized composite in rendering the real-time applications.

Assessment of the Synergetic Performance of Nanostructured CeO2-SnO2/Al2O3 Mixed Oxides on Automobile Exhaust Control.

In order to control diesel exhaust emission, CeO2-SnO2/Al2O3 (CTA) mixed oxides were prepared and coated on perforated stainless steel (SS) filter plates, and the catalytic activities were analyzed in this work. The CeO2-SnO2 (different compositions of Ce/Sn-2:8; 1:1; 8:2) composites and Al2O3 were prepared separately via a co-precipitation approach, and CeO2-SnO2/Al2O3 (CTA) mixed oxides were attained by mechanical mixing of 75 wt% CeO2-SnO2 composites with 25 wt% Al2O3. X-ray diffraction (XRD) and Raman spectroscopy were performed for all three CeO2-SnO2/Al2O3 (CTA) mixed oxides; the CeO2-SnO2/Al2O3 (Ce/Sn-1:1) sample confirmed the presence of cubic and tetragonal mixed faces, which enhances the redox nature (catalytic activities). Various characterizations such as high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) analysis, X-ray photoelectron spectroscopy (XPS), and a scanning electron microscope (SEM) were employed on CeO2-SnO2/Al2O3 (Ce/Sn-1:1) sample to investigate the structural, textural, compositional, and morphological properties. The CeO2-SnO2/Al2O3 (Ce/Sn-1:1) sample was coated on a perforated stainless steel (SS) filter plate via a simple, cost-effective, and novel method, and an exhaust emission test for various compression ratios (CR), injection pressure (IP), and load (L) was completed using an AVL Digas analyzer. The CeO2-SnO2/Al2O3 (Ce/Sn-1:1) sample, with a size of 10.22 nm and a high surface area of about 73 m2 g-1, exhibit appreciable catalytic properties.

Synergistic Effect of Reinforced Multiwalled Carbon Nanotubes and Boron Nitride Nanosheet-Based Hybrid Piezoelectric PLLA Scaffold for Efficient Bone Tissue Regeneration.

Electrospun poly(l-lactic acid) nanofibers (PLLANFs) have been receiving considerable attention in bone tissue engineering (BTE) due to their tunable biodegradability and remarkable in vitro and in vivo biocompatibility. However, deterioration in the mechanical strength of PLLANFs during the regeneration process leads to low osteoinductive performances. Additionally, their high hydrophobicity and limited piezoelectric properties have to be addressed concerning BTE. Herein, we report an efficient approach for fabricating high-performance PLLANF hybrid scaffolds for BTE by reinforcing amphiphilic triblock copolymer pluronic F-127 (PL)-functionalized nanofillers (PL-functionalized carboxylated multiwalled carbon nanotubes (PL-cMWCNTs) and PL-functionalized exfoliated boron nitride nanosheets (PL-EBN)). The synergistic reinforcement effect from one-dimensional (1D) electrically conducting PL-cMWCNTs and two-dimensional (2D) piezoelectric PL-EBN was remarkable in PLLANFs, and the obtained PL-Hybrid (PL-cMWCNTs + PL-EBN) reinforced scaffolds have outperformed the mechanical strength, wettability, and piezoelectric performances of pristine PLLANFs. Consequently, in vitro biocompatibility results reveal the enhanced proliferation of MC3T3-E1 cells on PL-Hybrid nanofiber scaffolds. Furthermore, the ALP activity, ARS staining, and comparable osteogenic gene expression results demonstrated significant osteogenic differentiation of MC3T3-E1 cells on PL-Hybrid nanofiber scaffolds than on the pristine PLLANF scaffold. Thus, the reported approach for constructing high-performance piezoelectric biodegradable scaffolds for BTE by the synergistic effect of PL-cMWCNTs and PL-EBN holds great promise in tissue engineering applications.

An mm-sized biomimetic directional microphone array for sound source localization in three dimensions.

Fly Ormia ochracea ears have been well-studied and mimicked to achieve subwavelength directional sensing, but their efficacy in sound source localization in three dimensions, utilizing sound from the X-, Y-, and Z-axes, has been less explored. This paper focuses on a mm-sized array of three Ormia ochracea ear-inspired piezoelectric MEMS directional microphones, where their in-plane directionality is considered a cue to demonstrate sound source localization in three dimensions. In the array, biomimetic MEMS directional microphones are positioned in a 120° angular rotation; as a result, six diaphragms out of three directional microphones keep a normal-axis relative to the sound source at six different angles in the azimuth plane starting from 0° to 360° in intervals of ±30°. In addition, the cosine-dependent horizontal component of the applied sound gives cues for Z-axis directional sensing. The whole array is first analytically simulated and then experimentally measured in an anechoic chamber. Both results are found to be compliant, and the angular resolution of sound source localization in three dimensions is found to be ±2° at the normal axis. The resolution at the azimuth plane is found to be ±1.28°, and the same array shows a ± 4.28° resolution when sound is varied from the elevation plane. Looking at the scope within this area combined with the presented results, this work provides a clear understanding of sound source localization in three dimensions.

Grape Seed Extract Assisted Synthesis of Dual-Functional Anatase TiO2 Decorated Reduced Graphene Oxide Composite for Supercapacitor Electrode Material and Visible Light Photocatalytic Degradation of Bromophenol Blue Dye.

The grape extract is a potential natural reducing agent because of its high phenolic content. The extracts of seeds, skin, and pulp of grape were prepared by digestion, grinding, and soxhlet methods and used for reducing graphene oxide (GO). The reduced GO made using the soxhlet extract of grape seed (GRGO) was hydrothermally treated with titanium dioxide (TiO2) for the synthesis of GRGO-TiO2 nanocomposite. The X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV-vis, photoluminescence, and Raman spectra studies further confirmed the formation of GRGO and the GRGO-TiO2 hybrid. Scanning electron microscope and transmission electron microscope studies showed the decoration of spherical TiO2 particles (<100 nm) on the few-layered GRGO sheets. The GRGO-TiO2 hybrid was explored as a working electrode for supercapacitors and visible light photocatalyst for water decontamination. GRGO-TiO2 showed higher specific capacitance (175 F g-1) than GRGO (150 F g-1) and TiO2 (125 F g-1) in an aqueous electrolyte. GRGO-TiO2 exhibited 83.6% capacitance retention even after 2000 cycles, indicating the good stability of the material. Further, under visible light irradiation (λ > 400 nm), GRGO-TiO2 showed ∼30% higher photo-oxidation of the bromophenol blue (BPB) dye than TiO2. Also, GRGO-TiO2 decreased the total organic carbon content of BPB from 92 to 18 ppm. Overall, the soxhlet extract of grape seed was found to be a cost-effective reducing agent for the preparation of GRGO, which is a suitable material to be used in supercapacitors and photocatalysis.

Sound source localization by Ormia ochracea inspired low-noise piezoelectric MEMS directional microphone.

The single-tone sound source localization (SSL) by majority of fly Ormia ochracea's ears-inspired directional microphones leaves a limited choice when an application like hearing aid (HA) demands broadband SSL. Here, a piezoelectric MEMS directional microphone using a modified mechanical model of fly's ear has been presented with primary focus to achieve SSL in most sensitive audio bands to mitigate the constraints of traditional SSL works. In the modified model, two optimized rectangular diaphragms have been pivoted by four optimized torsional beams; while the backside of the whole structure has been etched. As a result, the SSL relative to angular rotation of the incoming sound depicts the cosine dependency as an ideal pressure-gradient sensor. At the same time, the mechanical coupling leads the magnitude difference between two diaphragms which has been accounted as SSL in frequency domain. The idea behind this work has been analytical simulated first, and with the convincing mechanical results, the designed bio-inspired directional microphone (BDM) has been fabricated using commercially available MEMSCAP based on PiezoMUMPS processes. In an anechoic chamber, the fabricated device has been excited in free-field sound, and the SSL at 1 kHz frequency, rocking frequency, bending frequency, and in-between rocking and bending frequencies has been found in full compliance with the given angle of incidence of sound. With the measured inter-aural sensitivity difference (mISD) and directionality, the developed BDM has been demonstrated as a practical SSL device, and the results have been found in a perfect match with the given angle of incidence of sound. Furthermore, to facilitate the SSL in noisy environment, the noise has been optimized in all scopes, like the geometry of the diaphragm, supportive torsional beam, and sensing. As a result, the A-weighted noise of this work has been found less than 23 dBA across the audio bands, and the equivalent-input noise (EIN) has been found to be 25.52 dB SPL at 1 kHz frequency which are the lowest ever reported by a similar device. With the developed SSL in broadband-in addition to the lowest noise-the developed device can be extended in some audio applications like an HA device.

Nernst-Planck analysis of reverse-electrodialysis with the thin-composite pore-filling membranes and its upscaling potential.

To properly design reverse electrodialysis (RED) stacks, modeling of ion transport and prediction of power generation on the single RED stack are very important. Currently, the Nernst-Planck equation is widely adopted to simulate ion transport through IEMs. However, applying typical Nernst-Planck equation is not proper to analyze ion transport through the heterogeneous thin-composite pore-filling membrane because of the non-conductive site in the membrane matrix. Herein, we firstly introduced modified Nernst-Planck equation by addressing conductive traveling length (CTL) to simulate the ion transport through the thin-composite pore-filling membranes and the performance of a single RED stack with the same membranes. Also, 100 cell-pairs of RED stacks were assembled to validate modified Nernst-Planck equation according to the flow rate and membrane types. Under the OCV condition, the conductivity of the effluents was measured to validate the modified Nernst-Planck equation, and differences between modeling and experiments were less than 1.5 mS/cm. Theoretical OCV and current density were estimated by using modified Nernst-Planck equation. In particular, hydrophobicity on the surface of the heterogeneous membrane was considered to describe ion transport through the pore-filling membranes. Moreover, power generation from RED stacks was calculated according to the flow rate and the number of cell pairs.

RF magnetron sputtering mediated NiTi/Ag coating on Ti-alloy substrate with enhanced biocompatibility and durability.

Mechanically robust, biocompatible and corrosion resistant Ag doped NiTi (NiTi/Ag) coatings were formed on implant grade commercially pure titanium substrates by R.F. magnetron sputtering. Five samples with varying silver content (0, 1, 3, 7, and 10 at.%) were prepared by controlling the power applied to Ag and NiTi targets. The intensity of X-ray photoelectron spectra peaks corresponding to Ni2p, Ti2p, Ag3d components were found proportional to respective coating compositions. The soft Ag crystallites were decreased the roughness and crystallinity of NiTi/Ag. Among all compositions, NiTi/Ag coating with 3 at.% Ag exhibited lowest friction coefficient (0.1) and wear rate (0.69 × 10-07 mm3/N ∗ mm). Electrochemical corrosion measurements indicated that Ag incorporation increased the corrosion resistance of NiTi. Increase in Ag content shifted Ecorr values in the anodic direction, and reduced the current density by one-order-of-magnitude. When cultured on NiTi/Ag coating with 3 at.% Ag, human dermal fibroblast neonatal cells demonstrated highest cell viability. The fluorescence micrographic image of the immunostained cells showed a well grown actin filament network. Overall, NiTi/Ag coated titanium substrates were found to be a promising orthopedic implant material.

Whole genome sequencing of Gyeongbuk Araucana, a newly developed blue-egg laying chicken breed, reveals its origin and genetic characteristics.

Chicken, Gallus gallus, is a valuable species both as a food source and as a model organism for scientific research. Here, we sequenced the genome of Gyeongbuk Araucana, a rare chicken breed with unique phenotypic characteristics including flight ability, large body size, and laying blue-shelled eggs, to identify its genomic features. We generated genomes of Gyeongbuk Araucana, Leghorn, and Korean Native Chicken at a total of 33.5, 35.82, and 33.23 coverage depth, respectively. Along with the genomes of 12 Chinese breeds, we identified genomic variants of 16.3 million SNVs and 2.3 million InDels in mapped regions. Additionally, through assembly of unmapped reads and selective sweep, we identified candidate genes that fall into heart, vasculature and muscle development and body growth categories, which provided insight into Gyeongbuk Araucana's phenotypic traits. Finally, genetic variation based on the transposable element insertion pattern was investigated to elucidate the features of transposable elements related to blue egg shell formation. This study presents results of the first genomic study on the Gyeongbuk Araucana breed; it has potential to serve as an invaluable resource for future research on the genomic characteristics of this chicken breed as well as others.

Identification of exonic nucleotide variants of the thyroid hormone responsive protein gene associated with carcass traits and Fatty Acid composition in korean cattle.

The thyroid hormone responsive protein (THRSP) gene is a functional gene that can be used to indicate the fatty acid compositions. This study investigates the relationships of exonic single nucleotide polymorphisms (SNPs) in the THRSP gene and fatty acid composition of muscle fat and marbling score in the 612 Korean cattle. The relationships between fatty acid composition and eight SNPs in the THRSP gene (g.78 G>A, g.173 C>T, g.184 C>T, g.190 C>A, g.194 C>T, g.277 C>G, g.283 T>G and g.290 T>G) were investigated, and according to the results, two SNPs (g.78 G>A and g.184 C>T) in exon 1 were associated with fatty acid composition. The GG and CC genotypes of g.78 G>A and g.184 C>T had higher unsaturated fatty acid (UFA) and monounsaturated fatty acid (MUFA) content (p<0.05). In addition, the ht1*ht1 group (Val/Ala haplotype) in a linkage disequilibrium increased MUFAs and marbling scores for carcass traits (p<0.05). As a result, g.78 G>A and g.184 C>T had significantly relationships with UFAs and MUFAs. Two SNPs in the THRSP gene affected fatty acid composition, suggesting that GG and CC genotypes and the ht1*ht1 group (Val/Ala haplotype) can be markers to genetically improve the quality and flavor of beef.

Detection of exonic variants within the melanocortin 1 receptor (MC1R) gene in Black Silky, White Leghorn and Golden duckwing Araucana chicken.

The melanocortin 1 receptor (MC1R) gene can be considered a candidate functional gene for the pigmentation of plumage color. The aim of this study was to investigate the association between the genotype frequencies of g.69 T>C, g.376 G>A and g.427 A>G SNPs within the MC1R gene in Black silky (O), Golden duckwing Araucana (GA) and White Leghorn (W). The CC and AA genotype frequencies of g.69 T>C and g.427 A>G SNPs in White Leghorn (W) were both 1.000, and the TT genotype frequency of the g.69 T>C SNP in Golden duckwing Araucana (GA) was also 1.000. The GG and AA genotype frequencies of g.376 G>A and g.427 A>G SNPs in Black silky (O) were both 0.100. When a haplotype is observed using a combination of markers, a Golden duckwing Araucana (GA) can especially be distinguished when it is a TAG, TGG and TAA type in the SNP combination of the MC1R gene. In case of the CAA types, only White Leghorn (W) could specifically be distinguished. Therefore, three SNPs in MC1R may provide identification in chicken breeds.

Identification of Stearoyl-CoA Desaturase (SCD) Gene Interactions in Korean Native Cattle Based on the Multifactor-dimensionality Reduction Method.

Fat quality is determined by the composition of fatty acids. Genetic relationships between this composition and single nucleotide polymorphisms (SNPs) in the stearoyl-CoA desaturase1 (SCD1) gene were examined using 513 Korean native cattle. Single and epistatic effects of 7 SNP genetic variations were investigated, and the multifactor dimensionality reduction (MDR) method was used to investigate gene interactions in terms of oleic acid (C18:1), mono-unsaturated fatty acids (MUFAs) and marbling score (MS). The g.6850+77 A>G and g.14047 C>T SNP interactions were identified as the statistically optimal combination (C18:1, MUFAs and MS permutation p-values were 0.000, 0.000 and 0.001 respectively) of two-way gene interactions. The interaction effects of g.6850+77 A>G, g.10213 T>C and g.14047 C>T reflected the highest training-balanced accuracy (63.76%, 64.70% and 61.85% respectively) and was better than the individual effects for C18:1, MUFAs and MS. In addition, the superior genotype groups were AATTCC, AGTTCC, GGTCCC, AGTCCT, GGCCCT and AGCCTT. These results suggest that the selected SNP combination of the SCD1 gene and superior genotype groups can provide useful inferences for the improvement of the fatty acid composition in Korean native cattle.

Molecular cloning of vitellogenin cDNA in rockfish (Sebastes schlegeli) and effects of 2,2'4,4'5,5'-hexachlorobiphenyl (PCB 153) on its gene expression.

Many environmental chemicals are known to affect sex steroid production and vitellogenesis through agonistic or antagonistic pathways. To investigate the estrogenic effect of 2,2'4,4'5,5'-hexachlorobiphenyl (PCB 153) on reproductive function, we have constructed a cDNA library and cloned a 320 base sequence encoding a partial VTG mRNA of rockfish (rVTG), Sebastes schlegeli. We have examined the expression level of rVTG mRNA level by northern blot analysis and measured levels of plasma estradiol-17beta (E2) and testosterone (T) by radioimmunoassay (RIA). Plasma concentrations of T in female and male injected with PCB 153 were not significantly different between two dosages of 0.16 mg/kg b.w. and 0.57 mg/kg b.w. However, plasma concentrations of E2 in female fish injected with PCB 153 at 0.16 mg/kg b.w. and 0.57 mg/kg b.w. increased after 12 h and 24 h. An rVTG mRNA transcript of approximately 4.0 kilo bases was extracted from hepatic tissue for northern blot analysis, and the effects of PCB 153 on rVTG mRNA expression in vivo with both male and female juvenile rockfish were examined. The level of rVTG mRNA expression increased only in female rockfish injected with both dose levels of PCB 153 after 48 h of exposure. The results of this study suggest that PCB 153 may produce VTG in female through a synergic effect with E2 resulting in indirect disruption.

Effect on abortion of feeding Korean pine needles to pregnant Korean native cows.

We studied the frequency and timing of abortion and the serum levels of 17beta-estradiol and progesterone in Korean native cows fed pine needles during pregnancy. Fifteen pregnant cows were randomly assigned to groups of 5. The control group was fed a concentrate and rice straw, and the other 2 groups were fed, in addition, either 1.3 or 2.7 kg (dry weight) of Korean pine needles daily, starting at an average of 91 d of gestation and continuing until 245 d of gestation. The health status of the dams and the viability of the fetuses were ascertained by rectal palpation and ultrasound scanning during pregnancy. Simultaneously, blood samples were collected for analysis of serum 17beta-estradiol and progesterone. Two abortions in mid-pregnancy (at 126 and 150 d of gestation) occurred in the group ingesting the higher daily amount of pine needles. Premature parturition occurred at 259 d of gestation in this group and at 241 and 252 d of gestation in the group ingesting the lower daily amount of pine needles. The serum 17beta-estradiol concentration was significantly higher (P < 0.05) at 4 mo of gestation and the serum progesterone level significantly lower (P < 0.05) at 8 mo of gestation in the group ingesting more pine needles daily than in either of the other 2 groups. These results suggest that the ingestion of pine needles may play a role in abortion in Korean native cows by increasing the serum 17beta-estradiol concentration and decreasing the serum progesterone concentration.

Endoscopic ultrasound-guided fine needle aspiration of the pancreas. Diagnostic utility and accuracy.

OBJECTIVE: Endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNAB) is regarded as a safe and reliable procedure for diagnosing and staging of pancreatic neoplasms. This study retrospectively evaluated both the diagnostic utility and accuracy of pancreatic EUS-FNABs and potential cytologic pitfalls when using Diff-Quik stain for on-site evaluation. STUDY DESIGN: Pancreatic EUS-FNABs performed between 1995 and 1998 were identified from the files of the Department of Pathology. All patients were studied via a linear-array ultrasound endoscope with an FNAB device. Immediate evaluation of the specimen by a pathologist using air-dried slides and Diff-Quik stain was done on all cases. An average of five passes (range, three to nine) were performed. Five cytologic categories were identified: nondiagnostic, benign, atypical, suspicious and malignant. EUS disease staging, histologic correlation and clinical follow-up were reviewed. RESULTS: Sixty-nine consecutive pancreative FNABs were evaluated in the study period. The patients comprised 38 females and 31 males with a mean age of 65 years (range, 36-83). Histologic correlation was available on 40 patients, and follow-up was available on the remaining 29. The cytologic diagnoses included: 31 malignant, 8 suspicious, 6 atypical, 20 benign and 4 nondiagnostic. Forty-three cases were true positive, 9 were true negative, 2 were false positive, and 11 were false negative. The overall sensitivity was 80% and specificity was 82%. CONCLUSION: The study showed that cytologic evaluation of pancreatic EUS-FNABs has 80% sensitivity and 82% specificity. False negative diagnosis was usually due to sampling error. A nondiagnostic cytologic diagnosis should be rendered in the absence of adequate sampling of a lesion. On-site cytologic evaluation of EUS-FNABs aids in guaranteeing specimen adequacy, and the pathologist should be trained to evaluate Diff-Quik-stained samples.