Index Properties Research Articles

A Comprehensive Review of Opportunities of Nanomaterials in Stabilization and Construction Industry

Nanomaterials can be defined as materials possessing, at minimum, one external dimension measuring 1-100nm. Nanomaterials can occur naturally, be created as the by-products of combustion reactions, or be produced purposefully through engineering to perform a specialized function. These materials can have different physical and chemical properties to their bulkform counterparts. Considering these particle sizes, a new approach is proposed to use the nanoparticles in the geotechnical engineering to understand the nature of soil as nanoparticles will interact with soil particles more efficiently due to the advantage of their size i.e. 1nm to 100nm. As the new construction sites has been significantly increased in the area of poorquality ground several new approaches of stabilizing the soil underneath are introduced and one of these techniques are using the nanoparticles to improve the index properties of soil as well as strength of soil so that desired stability can be achieved. Different types of nanomaterials which can be used for the purpose of stabilization of soil are SiO¬2, TiO2, Al2O3. This paper also addresses the use of nanomaterials in housing construction, comparing their influence at the technical-structural level. Materials such as titanium dioxide, carbon nanotubes, nano silica, nanocellulose, nano alumina, and nano clays were analyzed. It was obtained that these nanomaterials can improve the structural, thermal, and functional properties of construction materials. In addition, they are related to increased durability, increased mechanical strength (>20 %), reduced thermal conductivity, and self-cleaning capability. Therefore, the use of nanomaterials promises to improve the sustainability and efficiency of housing construction

Maternal insulinemic and inflammatory dietary patterns and risk of child neurodevelopmental delay.

Our aim was to assess the risk of higher insulinemic, inflammatory, and hyperglycemia potential in the diet during pregnancy with child neurodevelopmental delay. We enrolled 7,438 pregnant women participating in a prospective cohort study. The food frequency questionnaire was used to evaluate the empirical dietary index for hyperinsulinemia (EDIH), empirical dietary inflammatory pattern (EDIP), glycemic index (GI), and glycemic load (GL) during mid-pregnancy. Child neurodevelopmental assessment was conducted at 6-36 months postpartum using the Denver Developmental Screening Test-II (DDST-II) scale, and the Gesell Developmental Diagnosis Scale (GDDS) was administered to assess children who did not meet the criteria for passing the DDST-II screening. We documented 540 incident child neurodevelopmental delay cases over 7,438 pregnant women (median follow-up: 2 years). Pregnant women exhibiting the high levels of hyperinsulinemic or proinflammatory components, or GI encountered an elevated risk of child neurodevelopmental delay; HRs (95% CI) comparing highest to lowest dietary index quintiles were EDIH 1.48 (1.07,2.04; P trend = 0.017), EDIP 1.39 (1.05,1.84; P trend = 0.019) and GI 1.36 (1.02,1.81; P trend = 0.038). In sex-stratified analyses, these results remained significant only in boys (P trend = 0.018 for EDIH, P trend = 0.028 for EDIP, P trend = 0.029 for GI). The performance of combined model of EDIH and EDIP for boys is comparable to that of the combined model of EDIH, EDIP, and GI to assess the risk of neurodevelopmental delay (AUC [area under curve] 0.801 vs. AUC 0.830). Both values are higher than the AUC values achieved by models using either set of indicators individually. Our findings suggest that maternal consumption of diets with high insulinemic, inflammatory, or glycemic index properties may be associated with neurodevelopmental delays in children, particularly in boys. Higher insulinemic and inflammatory potentials in maternal diet may forecast neurodevelopmental delay in boys.

Properties of the forgotten index in bipolar fuzzy graphs and applications.

Topological indices are the numbers that remain constant under graph automorphism. Topological indices describe a network's connectivity, structure, and topological characteristics. These indices have many applications in crisp graphs. However, in many cases, it is observed that some situations can't be described using the idea of crisp graphs. So, to overcome this issue, the need to define topological indices for fuzzy and bipolar fuzzy graphs arises. The F-index, or the Forgotten Index, is a significant topological index. A bipolar fuzzy graph with two opposite-sided opinions of both the edges and vertices measures the impreciseness or uncertainties of the edges and vertices along the positive and negative sides. In this article, we have presented the Forgotten Index for bipolar fuzzy graphs. Then, we have proved some theorems regarding the F-index of numerous types of bipolar fuzzy graphs, such as regular bipolar fuzzy graphs, complete bipolar fuzzy graphs, etc., the bounds of the F-index in bipolar fuzzy graphs, and the relationships of the F-index with other topological indices in bipolar fuzzy graphs. We have applied the proposed topological index, the F-index for bipolar fuzzy graphs, to matrimonial websites to find potential life partners based on compatibility and discussed the application of the Forgotten Index in gene regulatory networks.

Titanium Dioxide: A Versatile Earth‐Abundant Optical Material for Photovoltaics

AbstractTitanium dioxide (TiO2) has long been receiving attention as a promising material for enhancing the performance of photovoltaic devices due to its tunable optoelectronic properties. This paper reviews the utilization of TiO2 in recent photovoltaic applications, focusing primarily on its role as an optical material. The fundamental properties of TiO2 are reviewed, such as its wide bandgap and unique property of tunable refractive index. Furthermore, various strategies are discussed to harness the fundamental properties of TiO2 to improve light absorption and charge carrier generation within various photovoltaic devices. Overall, the pivotal role of TiO2 as an Earth‐abundant and non‐critical optical material is highlighted for future advances in the power conversion efficiency and viability of photovoltaic technologies, paving the way for future research and developments aimed at achieving sustainable and cost‐effective solar energy conversion.

Exploring the interplay between body mass index and passive muscle properties in relation to grip strength and jump performance in female university students.

Women typically have a higher body fat content than men. Fat accumulation is associated with muscle weakness and alterations in mechanical properties. This study aims to determine the relationship between BMI and weight status with the mechanical properties of muscle and tendon. It was hypothesized that the stiffness and tone of the forearm muscle and Achilles tendon would be correlated with weight status and BMI. A cross-sectional study was conducted with 136 female university students. Grip strength was assessed using a dynamometer, body composition was analyzed through bioimpedance, and countermovement jump performance was evaluated with a force platform. Stiffness and tone were measured using the MyotonPro device. ANOVA was used to compare grip strength and countermovement jump performance according to body composition. The Pearson correlation coefficient was used to examine bivariate associations. Relative grip strength decreased with an increase in fat content, while forearm muscle stiffness and tone decreased with rising weight status and BMI. Stiffness of the Achilles tendon increased with an increase in fat content and showed a significant positive correlation with BMI. Multiple regression analysis revealed a weak correlation between BMI, body composition, and stiffness of the forearm muscles. The results of this study support the notion that the stiffness of the forearm muscles and Achilles tendon is correlated with BMI in young adult women. Furthermore, an increase in body fat percentage is linked to a decrease in mechanical properties and poorer muscle function.

Understanding the Role of Surface Chemistry in Nanocellulose Kink Formation: A Case Study of TEMPO-Mediated Oxidation.

This study found that the sources of cellulose have a significant effect on the parameters related to the kinks present in nanocellulose. During nanocellulose preparation, 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation induced partial depolymerization on whole cellulose and made the amorphous regions more susceptible to consequent mechanical treatment irrespective of cellulose sources. However, plant cellulose microfibrils were prone to break into shorter nanocellulose with fewer kinks, while bacterial and tunicate cellulose were more likely to bend rather than break, thus leading to the generation of more kinks. The kinks did not show significant effects on the size, crystallinity index, and thermal properties of nanocellulose for each cellulose source, though the kink numbers were positively related to the mechanical performance of nanocellulose. Collectively, this study elucidated the kink formation mechanisms and clarified the effects of kinks on nanocellulose performance, thus providing new insights into understanding the source and behaviors of microdefects present in nanocellulose.

Enhanced edge - intrude triangle metamaterial absorber with polarization insensitivity for S, C, X and Ku band applications

This paper presents a novel metamaterial absorber designed to function effectively across the S, C, X, and Ku frequency bands (2–18 GHz). The unit cell of the metamaterial absorber is derived from an edge-intruded triangular structure, exhibiting multiple resonances. It is thoughtfully designed to achieve fourfold symmetry, ensuring polarization insensitivity. The proposed structure, fabricated on an FR4 substrate with a metallic ground plane, demonstrates exceptional absorption peaks at 2.5 GHz (97%), 3.4 GHz (96.5%), 5.2 GHz (99%), 9.07 GHz (98.8%), 12 GHz (98.1%), 13.66 GHz (89.1%), and 16 GHz (98.9%). The absorber’s four-fold symmetric design ensures polarization insensitivity, while its ultra-thin profile (0.013λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda$$\\end{document}) offers several practical benefits. By harnessing the unique properties of near-zero refractive index (NZRI) metamaterials, this absorber has the capability for precise control over electromagnetic waves. Its outstanding performance and versatility position it as a strong candidate for applications such as wavefront shaping, beam steering, sensing, and electromagnetic cloaking.

Comparative Dissolution Study of Ciprofloxacin Hydrochloride-sustained Release Tablets by Using Carbopol-934 and Guar Gum Polymers

Aims: This study aimed to identify the potential release of the drug from the tablet dosage form using Carbopol-934 and Guar Gum polymers at different concentration ratios. Objective: The objective of this study was to determine the cumulative percentage of ciprofloxacin hydrochloride released from different polymers. Method: We formulated ciprofloxacin hydrochloride sustained-release tablets with Carbopol-934 and Guar gum using the wet granulation method. For the formulation of sustained-release ciprofloxacin hydrochloride tablets, both polymers were mixed in varying ratios. The tablets were examined for pre-formulation studies, including the angle of repose, bulk density, compressibility index, and physiological properties, such as variations in weight, friability, and drug content. For postformulation studies, such as the in vitro study, the in vitro release of the drugs was evaluated in a phosphate buffer solution (pH 7.4) for 8 h. However, the physiological properties of ciprofloxacin hydrochloride tablets were limited due to their liberality. Results: The tablets containing guar gum (Batches B-I and B-II) showed better drug content than other polymer-based batches, such as Carbopol-934 (Batch A-I, A-II) and a mixture of both polymer Carbopol-934 and Guar gum (Batch C-I, C-II). Sustained drug release was observed in the guar gum polymer-based tablets (Batch B-II). It was observed that the dissolution profile of ciprofloxacin hydrochloride tablets formed using different polymers showed an increase in the polymer ratio, which can be related to the increase in drug release. Conclusion: From this study, we can conclude that the ciprofloxacin hydrochloride drug release percentage was maximum when guar gum polymer was used in the tablet dosage form.

Assessing Alterations of Rainfall Variability Under Climate Change in Zengwen Reservoir Watershed, Southern Taiwan

This study aims to detect changes in rainfall variability caused by climate change for various scenarios in the CMIP6 (Coupled Model Intercomparison Project Phase 6) multi-model ensemble. Projected changes in rainfall unevenness in terms of different timescale indices using three categories, namely WD50 (number of wettest days for half annual rainfall), SI (seasonality index), and DWR (ratio of dry-season to wet-season rainfall) are analyzed in Zengwen Reservoir watershed, southern Taiwan over near future (2021–2040) and midterm future (2041–2060) relative to the baseline period (1995–2014) under SSP2-4.5 and SSP5-8.5 scenarios. The projected rainfall for both baseline and future periods is derived from 25 GCMs (global climate models). The results indicate that noticeably deteriorated rainfall unevenness is projected in the Zengwen Reservoir watershed over future periods, which include decreased WD50, increased SI, and decreased DWR. Though there were noticeable differences in the rainfall projections by the different GCMs, the overall consensus reveals that uncertainties in future rainfall should not be ignored. In addition, WD50 has the greatest deviated relative change in mean, which implies that the short-timescale rainfall unevenness index is easily affected by climate change in the study area. Distributional changes in rainfall unevenness determined by simultaneously considering alterations in relative changes in mean and standard deviation indicated that there was no single dominant category. However, the top two categories, with summed frequencies exceeding 0.5, characterize different properties of rainfall unevenness indices. The top two categories of WD50 and SI commonly have decreased mean and increased mean, respectively, but nearly equal frequencies of the top two categories in DWR exhibit opposite variations. The proposed rainfall unevenness change detection approach provides a better understanding of the impacts of climate change on rainfall unevenness, which is useful for preparing adaptive mitigation measures for coping with disasters induced by climate change.

Foundation Model Study on Inorganic and Biopolymer Nano Additives Treated Soil—A Step Forward in Nano Additive Soil Stabilization

For almost a decade, various studies have been carried out to prove the suitability of nano additives in enhancing the geotechnical properties of soil. Yet, this line of research is still in its elementary stage, restricting itself to laboratory tests to determine soil’s index and engineering properties blended with varying dosages of nano additives. In other words, research on practical applications of nano additives for soil stabilization is scarce. The present work attempts to investigate the suitability of three different nanomaterials as a load-bearing stratum for shallow foundations. The nano additives were chosen in such a way that each of them is from a different origin. One of them is nano calcium carbonate (inorganic) whereas the other two are nano-sized varieties of natural biopolymers, namely nano chitosan (crustacean-based) and nano carboxymethyl cellulose (plant-based). A series of laboratory tests were initially conducted to determine the strength of all three nano-additive-treated soils at different dosages, which were investigated for 180 days to ensure their long-term performance. This was followed by a foundation model study on untreated soil and on soil treated with optimal dosages of nano additives. The results were validated using finite element software followed by a parametric study to optimize the depth of soil stabilization. It was observed that all three nano additives exhibited a better performance when the top layer had the optimal dosage and the subsequent layers had a relatively lesser dosage.

Laboratory Study on Synthesis of Geopolymer Fly ash sand

Abstract Sand is a naturally occurring resource that’s often employed in the field of civil engineering. Natural river sand is become harder to come by as a result of increased building activity. This is leading to several environmental issues, including erosion, landslides, tsunamis, river bank scoring, etc. Therefore, the creation of an alternate granular material is required to meet the required demand for natural river sand Geopolymers are utilized as an alternative binder material since they are three-dimensional alumina silicate frameworks with extremely high mechanical strength. Although the direct application of fly is widely recognized in practice, fly ash granule production and its applications are not. This artificial sand is being created utilizing fly ash, industrial waste, and a laboratory-scale disc granulator that uses geopolymerization. byproduct with different NaOH molarities and Na2SiO3 alkaline binders. This study’s primary goal is to create fly ash sand (GPS) and evaluate it using an index and engineering properties of river sand that is naturally occurring. These properties include water absorption, specific surface area, optimal and maximum dry density, grain size distribution, angle of shearing resistance, permeability, and more, in addition to geoenvironmental characteristics like pH, EC, and TDS. The findings indicated that GPS can be utilized as a building material in place of NRS since it interprets the same qualities as that of natural river sand.

Core prominence as a signature of restarted jet activity in the LOFAR radio-galaxy population

Context. Recurrent phases of dormancy and activity occur in the supermassive black holes in active galactic nuclei. Characterizing the duty cycles of this process is crucial in understanding the impact of the energy released on the host galaxies, and their evolution. However, it is challenging to identify sources in the quiescent and restarted phases. Aims. Our goal is to identify and characterize a substantial sample of radio galaxies in a restarted phase and explore the idea of core prominence as a signature of restarted activity. We expand our prior study of identifying restarted sources from a 30 deg2 area in the Lockman Hole to a larger 424 deg2 region in the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) extragalactic field using a sample of core-dominated radio galaxies selected visually. Methods. We used the 144 MHz LOFAR survey images of the HETDEX field to identify galaxies with restarting jets. By assessing diverse selection criteria including radio core dominance along with low surface brightness extended emission, spectral index properties (e.g., steep or inverted spectra of a core and an ultra-steep spectrum of extended emission), and morphology, we found 69 candidate restarted radio galaxies in the HETDEX field. Results. The restarted candidates show a diverse intrinsic morphology, spanning from FRI, FRII, core-with-halo, to asymmetric forms, feasibly proposing different progenitors. Within these 69 restarted candidates, we identified a subset of nine galaxies characterized by ultra-steep spectrum extended emission combined with high radio core prominence, representing previous and current epochs of jet activity. We interpret our findings for this small subset as support for a model in which the switch-on and switch-off mechanism happens with a relatively fast duty cycle in these sources. We found a peculiar case, J131728.61+561544.8, which appears to have altered its jet orientation, possibly due to changes in the angular momentum or spin of its supermassive black hole, interactions with surrounding material, and/or variations in the magnetic flux threading its accretion disk. Conclusions. The restarted candidates span a range of radio luminosities from log10(L144 MHz/WHz−1) = 23.24 to log10(L144 MHz/WHz−1) = 26.80, and linear sizes between 88 and 1659 kpc at 144 MHz, with 16 sources identified as giant radio galaxies with sizes exceeding 0.7 Mpc. The total stellar content of restarted sources is consistent with massive elliptical galaxies, with at least 17% inhabiting cluster environments. Our findings at z < 0.4 suggest that many restarting radio galaxies are not found in rich cluster environments, aligning with the environmental properties of the broader radio-galaxy population. The present study confirms the core prominence as an effective parameter for selecting candidate restarted radio sources.

Variations in Water Quality Index and Physicochemical Properties of Surface Water and Bottom Sediments of Selected Coastal Beaches of Niger Delta, Southern Nigeria

Variations in Water Quality Index and Physicochemical Properties of Surface Water and Bottom Sediments of Selected Coastal Beaches of Niger Delta, Southern Nigeria

Contributions to Generalized Oscillation Theory of Linear Hamiltonian Systems

In this paper we present several new contributions to the oscillation theory of linear differential equations, in particular of linear Hamiltonian systems, when the traditional Legendre condition is absent. Following our recent work (Discrete Contin. Dyn. Syst. 43(12):4139–4173, 2023), we introduce the multiplicity of a generalized right focal point and derive the corresponding local Sturmian separation theorem. We also examine the relation between the existence of finitely many generalized right focal points, or in the special case the nonexistence of generalized right focal points, with the Legendre condition. As the main tools we use new notions of the minimal multiplicities at a given point and the dual comparative index — an object from matrix analysis or differential geometry (Maslov index theory). Furthermore, we study local limit properties of the dual comparative index and the comparative index and apply them for deriving new oscillation results phrased in terms of the generalized right and left focal points. The investigation of the interplay between generalized right and left focal points leads to conditions characterizing the situation, when in the local Sturmian separation theorem the corresponding multiplicities attain the minimal possible value. This also provides a generalization of the concepts of the right and left proper focal point defined by Kratz (Analysis 23(2):163–183, 2003) and Wahrheit (Int. J. Differ. Equ. 2(2):221–244, 2007) to the setting, which does not impose the Legendre condition. The results are new even for completely controllable linear Hamiltonian systems, including the Sturm–Liouville differential equations of arbitrary even order.

Skip index: Supporting efficient inter-block queries and query authentication on the blockchain

Decentralized applications, the driving force behind the new Web3 paradigm, require continuous access to blockchain data. Their adoption, however, is hindered by the constantly increasing size of blockchains and the sequential scan nature of their read operations, which introduce a clear inefficiency bottleneck. Also, the growing amount of data recorded on the blockchain makes resource-constrained light nodes dependent on untrusted full nodes for fetching information, with a consequent need for query authentication protocols ensuring result integrity. Motivated by these reasons, in this paper we propose the skip index, an indexing data structure that allows users to quickly retrieve information simultaneously from multiple blocks of a blockchain. Our solution is also designed to be used as an authenticated data structure to guarantee the integrity of query results for light nodes. We discuss the theoretical properties of skip indices, propose efficient algorithms for their construction and querying, and detail their computational complexity. Finally, we assess the effectiveness of our proposal through an experimental evaluation on the Ethereum blockchain. As a reference use case, we focus on the popular CryptoKitties application and simulate a scenario where users seek to retrieve the events generated by the service. Our experimental results suggest that the use of skip indices offers a constant multiplicative speedup, thanks to search times that are at most logarithmic within a chosen search window. This allows to reduce the number of visited blocks by up to two orders of magnitude if compared to the naive sequential approach currently in use.

A facile sunflower pectin gel foam for liquid fuel fire suppression with ReaxFF characterisation on its char-enhancing ability

A biomass fire suppression gel foam (FSGF) with outstanding thermal stability and fire resistance performance was synthesised to improve the flame retardancy of foam agents on liquid fuel fires. The foam comprehensive index, microstructure, thermal stability, fire resistance and extinguishing properties of the FSGF were benchmarked against aqueous film-forming foam (AFFF). Subsequently, reactive forcefield (ReaxFF) molecular dynamics (MD) simulations were performed on the FSGF to study the thermokinetic properties. Based on the experimental results, a porosity layer was found on the external film of FSGF, which enhanced the thermal stability of the foam. The gelling mechanism of the foam is the formation of an O–Ca–O bond. Through MD simulations it was discovered that the remained calcium oxide/hydroxide species when deposited on fuel surfaces would promote char formation as they capture H/O atoms via dehydration. Alternatively, the foam showed better thermal stability than that of AFFF due to a lower weight loss rate and longer collapse time. The extinguishing performance tests demonstrated that the fire extinguishing time and resistance time of FSGF respectively are 72 s and 801 s, showing a significant potential to suppress the re-ignition of tank fires.

Uncertainty reduction in MASW inversion and ground response analysis using a-priori information

Multi-channel analysis of surface waves (MASW) method is commonly used for estimating the shear wave velocity (Vs) profile of soil and subsequent ground response analysis (GRA). However, the uncertainties from inversion non-uniqueness in MASW testing and the absence of soil type information in GRA can undermine their accuracy and affect seismic designs. Incorporating a-priori information from geotechnical investigations can be a potential solution, but its effectiveness in MASW testing is not well understood. This study aims to quantify the uncertainty reduction achieved by incorporating a-priori information in MASW testing and GRA. Extensive numerical simulations of MASW and GRA for nine idealized soil profiles were carried out. Subsequently, the findings were validated by carrying out field testing with and without a-priori information. The a-priori information included number and thickness of soil layers, soil type and index properties. The findings demonstrate that incorporating a-priori information significantly reduces inversion uncertainty in MASW and GRA, enhancing the reliability and accuracy of the analyses. This work provides a quantitative assessment of uncertainty reduction using a-priori information for different possible site and earthquake scenarios. The findings have important implications for design of earthquake-resistant structures and for improving the safety of people and infrastructure in earthquake-prone areas.

Some basic mathematical properties of the misbalance hadeg index of graphs

Some basic mathematical properties of the misbalance hadeg index of graphs

Tensile strength and durability performances-based evaluation of 3D-printed and mold-cast fibrous geopolymer composites produced at various alkaline activator combinations

This study aimed to investigate the effects of the sodium silicate-to-sodium hydroxide ratio, SH molarity, and carbon fiber volume fraction on the tensile strength and durability properties of mold-cast and 3D-printed geopolymer composites, including flexural and splitting tensile strengths, ultrasonic pulse velocity, water absorption, sorptivity index, and chloride penetration properties. For that purpose, the ground-granulated blast furnace slag and fly ash were employed as alumino-silicate-rich raw material. In order to activate the alumino-silicate-rich raw material, two sodium silicate/sodium hydroxide ratios of 1 and 2 and three sodium hydroxide molarities of 8M, 10M, and 12M were designated. Furthermore, carbon fiber was incorporated into the geopolymer composites at three volume fractions: 0 %, 0.3 %, and 0.6 %. In total, 18 nonfibrous and fibrous geopolymer composites were manufactured in two different ways: mold-cast and 3D-printed. The findings demonstrated that the strength and durability characteristics of 3D-printed specimens were inferior to those of mold-cast specimens, attributed to the presence of weak interfacial bonds between layers. It has been observed that the incorporation of carbon fiber has the effect of improving tensile strength performance. Nevertheless, the addition of carbon fiber led to a slight decrease in UPV values, and an increase in water absorption and sorptivity index values. Also, it adversely influenced the chloride penetration of geopolymer composites. The findings of the study also indicated that increasing the sodium hydroxide molarity had a positive impact on the strength and durability properties of the composites. Nevertheless, it was observed that increasing the sodium silicate-to-sodium hydroxide ratio led to a decrease in both tensile strength and durability performances. Additionally, the microstructure of the geopolymer composites was analyzed using scanning electron microscope (SEM) images.

Topological Edge Spectrum Along Curved Interfaces

Abstract We prove that if the boundary of a topological insulator divides the plane into two regions, each containing arbitrarily large balls, then it acts as a conductor. Conversely, we construct a counterexample to show that topological insulators that fit within strips do not need to admit conducting boundary modes. This constitutes a new setup where the bulk-edge correspondence is violated. Our proof relies on a seemingly paradoxical and underappreciated property of the bulk indices of topological insulators: they are global quantities that can be locally computed.