Carbon footprint and cost reduction by endoscopic grading of gastric intestinal metaplasia using narrow-band imaging.

BACKGROUND AND AIM: Gastric intestinal metaplasia (GIM) is a high-risk factor for the development of gastric cancer. Narrow-band imaging (NBI) enables endoscopic grading of GIM (EGGIM). In the era of climate change, gastrointestinal endoscopists are expected to reduce greenhouse gas emissions and medical waste. Based on the diagnostic performance of NBI endoscopy, this study measured the environmental impact and reduced cost of implementing EGGIM during gastroscopy. METHODS: Using NBI endoscopy in 242 patients, EGGIM classification and operative link on GIM (OLGIM) staging were prospectively performed in five different areas (lesser and greater curvatures of the corpus and antrum, and the incisura angularis). We estimated the environmental impact and cost reduction of the biopsy procedures and pathological processing if EGGIM were used instead of OLGIM. RESULTS: The diagnostic accuracy of NBI endoscopy for GIM was 93.0-97.1% depending on the gastric area. When a high EGGIM score ≥ 5 was the cut-off value for predicting OLGIM stages III-IV, the area under the curve was 0.862, sensitivity was 81.9%, and specificity was 90.4%. The reduction in the carbon footprint by EGGIM was -0.4059 kg carbon dioxide equivalents per patient, equivalent to 1 mile driven by a gasoline-powered car. The cost savings were calculated to be $47.36 per patient. CONCLUSIONS: EGGIM is a reliable method for identifying high-risk gastric cancer patients, thereby reducing the carbon footprint and medical costs in endoscopy practice.

Femtosecond-resolution optical pulse interleaving time error detector.

Pulse repetition rate multiplier (PRRM) is an essential component of microwave photonics systems, designed not only to alleviate photodiode saturation but also to provide more frequent pulses. However, the presence of interleaving time errors is known to compromise the advantages of PRRM. In this study, we present a high-sensitivity detection method for identifying these time errors using an electro-optic sampling-based timing detector (EOS-TD). We utilize two EOS-TDs: one for generating precise timing ruler signals and the other as a high-precision timing detector. In comparison to the conventional power ratio comparison method, our approach demonstrates sensitivity improvement by two orders of magnitude. This enhancement facilitates the measurement of femtosecond-level time errors. By enabling higher pulse rates while maintaining the ultralow jitter, this method can be useful for building higher-speed photonic systems.

Resection speed of endoscopic submucosal dissection according to the location of gastric neoplasia: a learning curve using cumulative sum analysis.

BACKGROUND: There is few study evaluating the relationship between endoscopic submucosal dissection (ESD) resection speed and the lesion characteristics of gastric neoplasia. We investigated the learning curve of consecutive ESDs using cumulative sum (CUSUM) analysis. METHODS: A total of 356 ESDs performed by a single endoscopist were grouped chronologically into three learning periods. The ESD procedure was defined to be fast when resection speed was > 9.0 cm2/hour. The CUSUM method was used to assess the number of ESDs required for achieving proficiency and mastery. RESULTS: Mean resection speed was significantly faster in Phase III (15.1 cm2/hour) compared to those in Phase I (9.3 cm2/hour) and II (11.4 cm2/hour) (p < 0.001). Tumors in the stomach's upper and middle third location were significantly associated with difficulty in attaining the fast resection speed (odds ratios, 0.05 and 0.36) compared to the lower third location. The number of ESDs required to achieve a competency for fast resection was 15 for tumors in the lower third of the stomach and 98 for those in the upper/middle third location, respectively. In the lower third location of the tumor, the CUSUM curve revealed that 75 cases were needed to achieve proficiency and 174 cases to achieve mastery. However, mastery was not achieved in ESD for the upper/middle third tumor during the study period. CONCLUSION: The time required to achieve relevant competency in gastric ESD depends on the tumor location.

Spontaneous Folding Growth of Graphene on h-BN.

Graphene has been the subject of much research, with structural engineering frequently used to harness its various properties. In particular, the concepts of graphene origami and kirigami have inspired the design of quasi-three-dimensional graphene structures, which possess intriguing mechanical, electronic, and optical properties. However, accurate controlling the folding process remains a big challenge. Here, we report the discovery of spontaneous folding growth of graphene on the h-BN substrate via adopting a simple chemical vapor deposition method. Folded edges are formed when two stacked graphene layers share a joint edge at a growth temperature up to 1300 °C. Using first-principles density functional theory calculations, the bilayer graphene with folded edges is demonstrated to be more stable than that with open edges. Utilizing this novel growth mode, hexagram bilayer graphene containing entirely sealed edges is eventually realized. Our findings provide a route for designing graphene devices with a new folding dimension.

Formation Mechanism of Chemically Precompressed Hydrogen Clathrates in Metal Superhydrides.

Recently, the experimental discovery of high-Tc superconductivity in compressed hydrides H3S and LaH10 at megabar pressures has triggered searches for various superconducting superhydrides. It was experimentally observed that thorium superhydrides, ThH10 and ThH9, are stabilized at much lower pressures than LaH10. Based on first-principles density functional theory calculations, we reveal that the isolated Th frameworks of ThH10 and ThH9 have relatively more excess electrons in interstitial regions than the La framework of LaH10. Such interstitial excess electrons easily participate in the formation of the anionic H cage surrounding the metal atom. The resulting Coulomb attraction between cationic Th atoms and anionic H cages is estimated to be stronger than the corresponding one of LaH10, thereby giving rise to larger chemical precompressions in ThH10 and ThH9. Such a formation mechanism of H clathrates can also be applied to other superhydrides such as CeH9, PrH9, and NdH9. Our findings demonstrate that interstitial excess electrons in the isolated metal frameworks of high-pressure superhydrides play an important role in generating the chemical precompression of H clathrates.

Scoring model for discriminating gastric cancer risk in patients with negative serum pepsinogen and anti-Helicobacter pylori antibody results.

BACKGROUND: The ABC test measures serum pepsinogen and anti-Helicobacter pylori IgG antibody levels to predict precancerous conditions in the stomach and gastric cancer. However, a limitation of this test is that the gastric cancer risk is not negligible in patients with a negative result. METHODS: Based on their ABC results, 1157 patients were classified into Groups A (n = 392), B (n = 479), C (n = 247), and D (n = 39). In Group A, 24.2% of patients had atrophic gastritis and/or intestinal metaplasia and had thus been incorrectly assigned to Group A. Patients in Group A were then assigned to derivation (n = 236) and validation (n = 156) cohorts by 3:2 random sampling. Logistic regression analyses were performed to identify the factors discriminating between a correct (true) and incorrect (false) Group A classification. RESULTS: A 4-point discriminative model was constructed based on a high-negative H. pylori IgG antibody titer and the patient's age (50-64 and ≥65 years). The areas under the receiver operating characteristic curve for the derivation and validation cohorts were 0.868 and 0.894, respectively. In the validation cohort, the addition of a discriminative model score ≥2 to the ABC method showed a similar accuracy for predicting gastric cancer risk compared with the ABC method alone (93.8% vs. 92.4%). CONCLUSION: The 4-point discriminative model may help identify patients with a normal serological test who are nonetheless at risk of developing gastric cancer.

Ferromagnetic Weyl Fermions in Two-Dimensional Layered Electride Gd_{2}C.

Recently, two-dimensional layered electrides have emerged as a new class of materials which possess anionic electrons in the interstitial spaces between cationic layers. Here, based on first-principles calculations, we discover a time-reversal-symmetry-breaking Weyl semimetal phase in a unique two-dimensional layered ferromagnetic (FM) electride Gd_{2}C. It is revealed that the crystal field mixes the interstitial electron states and Gd-5d orbitals near the Fermi energy to form band inversions. Meanwhile, the FM order induces two spinful Weyl nodal lines (WNLs), which are converted into multiple pairs of Weyl nodes through spin-orbit coupling. Further, we not only identify Fermi-arc surface states connecting the Weyl nodes but also predict a large intrinsic anomalous Hall conductivity due to the Berry curvature produced by the gapped WNLs. Our findings demonstrate the existence of Weyl fermions in the room-temperature FM electride Gd_{2}C, therefore offering a new platform to investigate the intriguing interplay between electride materials and magnetic Weyl physics.

Narrowband imaging with near-focus magnification for discriminating the gastric tumor margin before endoscopic resection: A prospective randomized multicenter trial.

BACKGROUND AND AIM: This study investigated the usefulness of near-focus narrowband imaging (NF-NBI) for determining gastric tumor margins compared with indigo carmine chromoendoscopy (ICC) before endoscopic submucosal dissection (ESD). METHODS: This prospective randomized controlled trial was conducted at seven teaching hospitals in Korea. Patients with gastric adenoma or differentiated adenocarcinoma undergoing ESD were enrolled and randomly assigned to the NF-NBI or ICC group. A marking dot was placed on the most proximal margin of the tumor before ESD. The primary endpoint was delineation accuracy, which was defined as presence of marking dots within 1 mm of the tumor margin under microscopic observation. RESULTS: A total of 200 patients in the NF-NBI group and 195 patients in the ICC group were included. The delineation accuracy rate was 84.5% in the NF-NBI group and 81.0% in the ICC group (P = 0.44). However, the distance from the marking dot to the margin of the tumor was significantly shorter in the NF-NBI group than in the ICC group (0.8 ± 0.8 vs 1.2 ± 1.3 mm, P < 0.01). Even after adjustment of other clinicopathological factors that are associated with difficulty of tumor delineation, NF-NBI did not show significant association with accurate delineation (odds ratio of 0.86, P = 0.60). CONCLUSIONS: This prospective multicenter study showed that NF-NBI is not superior to ICC in terms of accurately delineating gastric tumors (NCT02661945).

Analysis of factors associated with recovery of the serum pepsinogen ratio after Helicobacter pylori eradication: a long-term follow-up study in Korea.

Objective: Serum levels of pepsinogen (PG) are related to Helicobacter pylori-induced inflammation of the gastric mucosa. This study aimed to examine the influence of H. pylori eradication on serum PG, analyze its associated factors, and evaluate the long-term outcomes.Methods: H. pylori-positive patients who underwent gastroscopy and serum PG measurement were enrolled in a single academic hospital. After H. pylori eradication, the measurement of serum PG level was performed. Recovery of serum PG I/II ratio was defined as a PG I/II ratio after eradication of >3.0 in patients with a PG I/II ratio ≤ 3.0 before eradication. Follow-up involved serum PG measurement and gastroscopy with a rapid urease test annually.Results: In all, 327 patients were eligible for study inclusion. Compared to those before H. pylori eradication, serum PG I (74.9 vs. 44.3 ng/mL, p < .001) and PG II (25.4 vs. 9.1 ng/mL, p < .001) levels significantly decreased after successful eradication. In addition, there was a significant increase in serum PG I/II ratio after eradication (3.07 vs. 4.98, p < .001). In multivariate analyses, the following were independently associated with failed recovery of serum PG I/II ratio despite successful eradication: age ≥ 60 years (odds ratio [OR] = 0.231, 95% confidence interval [CI] = 0.084-0.629, p = .004) and severe gastric atrophy (OR = 0.156, 95% CI = 0.055-0.440, p < .001).Conclusions: Recovery of serum PG I/II ratio after H. pylori eradication may be achieved in H. pylori-infected patients aged <60 years without severe gastric atrophy.

Development and comparison of two H5N8 influenza A vaccine candidate strains.

Avian influenza viruses circulating in birds have caused outbreaks of infection in poultry and humans, thereby threatening public health. Recently, a highly pathogenic avian influenza (HPAI) virus (H5N8) of clade 2.3.4.4 emerged in Korea and other countries and caused multiple outbreaks in domestic and wild birds, with concerns for human infection. To combat HPAI viral infections, novel vaccines are likely to be the most effective approach. Therefore, in this study, we generated H5N8 vaccine candidate viruses based on a Korean isolate (A/broiler duck/Korea/Buan2/2014). The vaccine candidate viruses were 2:6 reassortants expressing the two surface glycoproteins of A/broiler duck/Korea/Buan2/2014 on an A/Puerto Rico/8/34 (PR8) backbone generated by using an eight-plasmid-based reverse genetics system with or without replacement of the multi-basic amino acid cleavage motif (MBCM, a crucial pathogenic factor in HPAI virus) with a bi-basic amino acid cleavage motif (BBCM) in their HA. An H5N8 vaccine candidate virus containing the BBCM showed attenuated pathogenesis in embryonated eggs and exhibited less virulence in the infected mice compared with the wild H5N8 virus containing an MBCM. Vaccination with an inactivated preparation of the vaccine candidate virus protected mice from lethal H5N8 viral challenge. This is the first report of the development and evaluation of H5N8 vaccine strains (with an MBCM or BBCM) of HA clade 2.3.4.4 as vaccine candidates. Our findings suggest that H5N8 strains with a BBCM instead of an MBCM might be considered for H5N8 vaccine seed virus development or as a reference vaccine against H5N8 viral strains.

Cost-effectiveness of a tailored Helicobacter pylori eradication strategy based on the presence of a 23S ribosomal RNA point mutation that causes clarithromycin resistance in Korean patients.

BACKGROUND AND AIM: The Helicobacter pylori eradication rate using conventional triple therapy has decreased due to clarithromycin (CAM) resistance in H. pylori. Recently, dual priming oligonucleotide (DPO)-based multiplex polymerase chain reaction (PCR) can be used to detect H. pylori and point mutations in the 23S ribosomal RNA gene causing CAM resistance. This study aimed to evaluate the success rate and cost-effectiveness of tailored H. pylori eradication using DPO-PCR. METHODS: The H. pylori-positive patients diagnosed by a rapid urease test or DPO-PCR were enrolled from a single academic hospital. The patients with positive rapid urease test results received a CAM-based triple regimen. In the tailored therapy group that underwent DPO-PCR testing, patients with A2142G and/or A2143G point mutations were treated with a bismuth-containing quadruple regimen. The cost-effectiveness of H. pylori eradication success was evaluated according to the average cost per patient and the incremental cost-effectiveness ratio. RESULTS: A total of 243 patients were allocated to the triple therapy group and 124 patients to the tailored therapy group. The first-line eradication rate of H. pylori was significantly higher in the tailored therapy group than in the conventional triple therapy group (92.7% vs 76.5%, P < 0.001). The average costs per patient for tailored therapy were $307.37 and $299.59 for first-line and second-line treatments, respectively. Compared with triple therapy, the incremental cost-effectiveness ratios of tailored therapy were $3.96 and -$3.81 per patient for first-line and second-line treatments, respectively. CONCLUSION: In Korea, tailored H. pylori eradication using DPO-PCR may be more cost-effective than conventional triple therapy.

Flatbands and Emergent Ferromagnetic Ordering in Fe_{3}Sn_{2} Kagome Lattices.

A flatband representing a highly degenerate and dispersionless manifold state of electrons may offer unique opportunities for the emergence of exotic quantum phases. To date, definitive experimental demonstrations of flatbands remain to be accomplished in realistic materials. Here, we present the first experimental observation of a striking flatband near the Fermi level in the layered Fe_{3}Sn_{2} crystal consisting of two Fe kagome lattices separated by a Sn spacing layer. The band flatness is attributed to the local destructive interferences of Bloch wave functions within the kagome lattices, as confirmed through theoretical calculations and modelings. We also establish high-temperature ferromagnetic ordering in the system and interpret the observed collective phenomenon as a consequence of the synergetic effect of electron correlation and the peculiar lattice geometry. Specifically, local spin moments formed by intramolecular exchange interaction are ferromagnetically coupled through a unique network of the hexagonal units in the kagome lattice. Our findings have important implications to exploit emergent flat-band physics in special lattice geometries.

Impact of patient audiovisual re-education via a smartphone on the quality of bowel preparation before colonoscopy: a single-blinded randomized study.

BACKGROUND AND AIMS: Education on preparation is essential for successful colonoscopy. This study aimed to evaluate the impact of audiovisual (AV) re-education via a smartphone on bowel preparation quality before colonoscopy. METHODS: A prospective, endoscopist-blinded, randomized, controlled study was performed. Patients who underwent colonoscopy with 3 purgatives, including 4 L of polyethylene glycol (4-L PEG), 2 L of PEG with ascorbic acid (2-L PEG/Asc), and sodium picosulfate with magnesium citrate (SPMC), were enrolled and randomized into the AV re-education via smartphone group (AV group, n = 160) and a control group (n = 160). The primary outcome was the quality of the bowel preparation according to the Boston Bowel Preparation Scale (BBPS). The secondary outcomes included instruction adherence using adherence score (AS) and patient satisfaction with education using a visual analog scale (VAS). RESULTS: A total of 283 patients (AV group, n = 139; control group, n = 144) were analyzed per protocol. The mean BBPS (7.53 vs 6.29, P < .001) and the proportion with adequate preparation were higher in the AV group. The mean BBPS of the AV group was significantly higher than that of the control group for the 2-L PEG/Asc and SPMC preparations, but not for the 4-L PEG preparation. The mean AS and the mean VAS score were all significantly higher in the AV group. Among the 3 purgatives, the mean AS was lowest in the 4-L PEG group (P = .041). CONCLUSIONS: AV re-education via smartphone was easy and convenient, and enhanced preparation quality, patient adherence to instructions, and patient satisfaction.

The Nature of Bonding in Bulk Tellurium Composed of One-Dimensional Helical Chains.

Bulk tellurium (Te) is composed of one-dimensional (1D) helical chains which have been considered to be coupled by van der Waals (vdW) interactions. However, on the basis of first-principles density functional theory calculations, we here propose a different bonding nature between neighboring chains: i.e., helical chains made of normal covalent bonds are connected together by coordinate covalent bonds. It is revealed that the lone pairs of electrons of Te atoms participate in forming coordinate covalent bonds between neighboring chains, where each Te atom behaves as both an electron donor to neighboring chains and an electron acceptor from neighboring chains. This ligand-metal-like bonding nature in bulk Te results in the same order of bulk moduli along the directions parallel and perpendicular to the chains, contrasting with the large anisotropy of bulk moduli in vdW crystals. We further find that the electron effective masses parallel and perpendicular to the chains are almost the same as each other, consistent with the observed nearly isotropic electrical resistivity. It is thus demonstrated that the normal/coordinate covalent bonds parallel/perpendicular to the chains in bulk Te lead to a minor anisotropy in structural and transport properties.

Competing Gap Opening Mechanisms of Monolayer Graphene and Graphene Nanoribbons on Strong Topological Insulators.

Graphene is a promising material for designing next-generation electronic and valleytronic devices, which often demand the opening of a bandgap in the otherwise gapless pristine graphene. To date, several conceptually different mechanisms have been extensively exploited to induce bandgaps in graphene, including spin-orbit coupling and inversion symmetry breaking for monolayer graphene, and quantum confinement for graphene nanoribbons (GNRs). Here, we present a multiscale study of the competing gap opening mechanisms in a graphene overlayer and GNRs proximity-coupled to topological insulators (TIs). We obtain sizable graphene bandgaps even without inversion symmetry breaking and identify the Kekulé lattice distortions caused by the TI substrates to be the dominant gap opening mechanism. Furthermore, Kekulé distorted armchair GNRs display intriguing nonmonotonous gap dependence on the nanoribbon width, resulting from the coexistence of quantum confinement, edge passivation, and Kekulé distortions. The present study offers viable new approaches for tunable bandgap engineering in graphene and GNRs.

Mycophenolic mofetil, an alternative antiviral and immunomodulator for the highly pathogenic avian influenza H5N1 virus infection.

Infection with the highly pathogenic avian influenza H5N1 virus results in a high incidence of mortality in humans. Severe complications from infection are often associated with hypercytokinemia. However, current neuraminidase inhibitors (NAIs) have several limitations including the appearance of oseltamivir-resistant H5N1 virus and the inability to completely ameliorate hyper-immune responses. To overcome these limitations, we evaluated the anti-viral activity of mycophenolic mofetil (MMF) against A/Vietnam/1194/2004 (H5N1) virus infection using MDCK cells and mice. The IC50 of MMF (0.94 µM) was comparable to that of zanamivir (0.87 µM) in H5N1 virus-infected MDCK cells based on ELISA. Time-course assays demonstrated that MMF completely inhibited H5N1 viral mRNA replication and protein expression for approximately 8 h after the initiation of treatment. In addition, MMF treatment protected 100% of mice, and lung viral titers were substantially reduced. The anti-viral mechanism of MMF against H5N1 virus infection was further confirmed to depend on the inhibition of cellular inosine monophosphate dehydrogenase (IMPDH) by exogenous guanosine, which inhibits viral mRNA and protein expression. Moreover, IL-1ß, IFN-ß, IL-6, and IP-10 mRNA expression levels were significantly downregulated in MDCK cells with MMF treatment. These results indicated that MMF could represent a novel inhibitor of viral replication and a potent immunomodulator for the treatment of H5N1 virus infection.

Multivalency-Driven Formation of Te-Based Monolayer Materials: A Combined First-Principles and Experimental study.

Contemporary science is witnessing a rapid expansion of the two-dimensional (2D) materials family, each member possessing intriguing emergent properties of fundamental and practical importance. Using the particle-swarm optimization method in combination with first-principles density functional theory calculations, here we predict a new category of 2D monolayers named tellurene, composed of the metalloid element Te, with stable 1T-MoS_{2}-like (α-Te), and metastable tetragonal (ß-Te) and 2H-MoS_{2}-like (γ-Te) structures. The underlying formation mechanism is inherently rooted in the multivalent nature of Te, with the central-layer Te behaving more metal-like (e.g., Mo), and the two outer layers more semiconductorlike (e.g., S). We also show that the α-Te phase can be spontaneously obtained from the magic thicknesses divisible by three layers truncated along the [001] direction of the trigonal structure of bulk Te, and both the α- and ß-Te phases possess electron and hole mobilities much higher than MoS_{2}. Furthermore, we present preliminary but convincing experimental evidence for the layering behavior of Te on HOPG substrates, and predict the importance of multivalency in the layering behavior of Se. These findings effectively extend the realm of 2D materials to group-VI elements.

Factors for improving the diagnostic efficiency of the rapid urease test from the gastric corpus.

OBJECTIVE: This study aimed to evaluate the optimal biopsy site for Helicobacter pylori detection by comparing the results of rapid urease test (RUT) between the gastric corpus and the antrum. METHODS: A biopsy specimen from each subject was obtained from the corpus and from the antrum. For each subject, the two specimens were separately immersed in two different RUT kits. Positive reaction times were measured at 20 minutes and 1, 3, and 24 hours. If either of the two RUT kits showed a positive reaction, H. pylori infection was confirmed. RESULTS: A total of 310 H. pylori-infected subjects were eligible for study inclusion. Compared with the antrum, positive RUT reaction times in the corpus were shorter when the degree of gastric atrophy was moderate or severe (p = .001 and p < .001, respectively). A multivariate analysis revealed that the factors resulting in a faster positive RUT reaction in the corpus were age ≥50 years (odds ratio [OR] = 1.84; 95% confidence interval [CI] = 1.10-3.08; p = .021) and severe gastric atrophy (OR = 2.41; 95% CI = 1.13-5.13; p = .023). Also, severe gastric atrophy was an independent factor associated with positive RUT reaction only in the corpus (OR = 5.12; 95% CI = 1.55-16.88; p = .007). CONCLUSIONS: In subjects aged ≥50 years or with severe gastric atrophy, biopsy of the corpus mucosa optimized the efficiency of H. pylori detection through a faster positive RUT reaction.

Contrasting diffusion behaviors of O and F atoms on graphene and within bilayer graphene.

Chemical modification of graphene with adatoms is of importance for nanoelectronics applications. Based on first-principles density-functional theory calculations including van der Waals interactions, we present a comparative study of the diffusion characteristics of oxygen (O) and fluorine (F) atoms both on graphene and between the layers of bilayer graphene. We find that the calculated diffusion barrier for the O atom increases slightly from 0.81 eV on graphene to 0.85 eV within bilayer graphene, while that for the F atom largely decreases from 0.30 eV on graphene to 0.18 eV within bilayer graphene. Such contrasting behaviors of the O and F diffusions within bilayer graphene can be traced to their different bonding natures: i.e., the O adatom that shows strongly covalent C-O-C bonding on the bridge site of the C-C bond diffuses on one graphene layer with a slight interference of the other layer, while the F adatom that shows semi-ionic F-C bonding on top of a C atom easily diffuses by hopping between two graphene layers by accepting more electron charges from the two layers. The present findings have important implications for the understanding of the diffusion processes of F and O atoms on graphene and within bilayer graphene.

Dimensionality and Valency Dependent Quantum Growth of Metallic Nanostructures: A Unified Perspective.

Quantum growth refers to the phenomena in which the quantum mechanically confined motion of electrons in metallic wires, islands, and films determines their overall structural stability as well as their physical and chemical properties. Yet to date, there has been a lack of a unified understanding of quantum growth with respect to the dimensionality of the nanostructures as well as the valency of the constituent atoms. Based on a first-principles approach, we investigate the stability of nanowires, nanoislands, and ultrathin films of prototypical metal elements. We reveal that the Friedel oscillations generated at the edges (or surfaces) of the nanostructures cause corresponding oscillatory behaviors in their stability, leading to the existence of highly preferred lengths (or thicknesses). Such magic lengths of the nanowires are further found to depend on both the number of valence electrons and the radial size, with the oscillation period monotonously increasing for alkali and group IB metals, and monotonously decreasing for transition and group IIIA-VA metals. When the radial size of the nanowires increases to reach ∼10 Å, the systems equivalently become nanosize islands, and the oscillation period saturates to that of the corresponding ultrathin films. These findings offer a generic perspective of quantum growth of different classes of metallic nanostructures.