Homeland Security Research Articles

Exciton-harvesting enabled efficient charged particle detection in zero-dimensional halides

Materials for radiation detection are critically important and urgently demanded in diverse fields, starting from fundamental scientific research to medical diagnostics, homeland security, and environmental monitoring. Low-dimensional halides (LDHs) exhibiting efficient self-trapped exciton (STE) emission with high photoluminescence quantum yield (PLQY) have recently shown a great potential as scintillators. However, an overlooked issue of exciton-exciton interaction in LDHs under ionizing radiation hinders the broadening of its radiation detection applications. Here, we demonstrate an exceptional enhancement of exciton-harvesting efficiency in zero-dimensional (0D) Cs3Cu2I5:Tl halide single crystals by forming strongly localized Tl-bound excitons. Because of the suppression of non-radiative exciton-exciton interaction, an excellent α/β pulse-shape-discrimination (PSD) figure-of-merit (FoM) factor of 2.64, a superior rejection ratio of 10−9, and a high scintillation yield of 26 000 photons MeV−1 under 5.49 MeV α-ray are achieved in Cs3Cu2I5:Tl single crystals, outperforming the commercial ZnS:Ag/PVT composites for charged particle detection applications. Furthermore, a radiation detector prototype based on Cs3Cu2I5:Tl single crystal demonstrates the capability of identifying radioactive 220Rn gas for environmental radiation monitoring applications. We believe that the exciton-harvesting strategy proposed here can greatly boost the applications of LDHs materials.

(Invited) Advancement in Electrosynthesis of Fuels and Chemicals Using H2O and/or CO2 and N2 at Intermediate Temperatures at Idaho National Laboratory

Fuels and commodity chemicals make up a significant share of the potential energy savings opportunities for decarbonized economy and society. New innovative technologies are needed that can reduce the amount of energy and carbon intensity currently required to produce the key fuels and chemicals or associated building blocks. Electrochemistry is playing an increasingly important role in manufacturing as we reduce energy use and address uncertain supply chains driven by industrial electrification. In comparison to processes driven by heat and pressure, electrochemically driven synthesis of fuels and chemicals provides unique opportunities for selective reactions and separations offering increased flexibility to manufacturing. As one of DOE’s premier multi-program energy research laboratories, Idaho National Laboratory’s (INL) mission is to ensure the nation’s energy security with safe, competitive and sustainable energy systems and unique national and homeland security capabilities. INL’s initiative, integrated energy systems (IES) provides carbon-free nuclear and renewable energy for downstream use in manufacturing and transportation. The manufacturing component of IES focuses on integrating clean, carbon-free electrons with waste/renewable heat and includes both manufacturing of electrochemical devices and implementing them in energy-efficient processes. In this talk, we will provide representative examples for the pillar of energy to molecules and materials (E2M2) by utilizing the protonic ceramic electrochemical cells/membrane reactors (PCEC/PCEMR). The electrochemical route using PCEC/PCEMR offers a solution of process intensification and low carbon intensity. We will also share our cost perspective when compared to other lower and higher temperature counterparts.

Measuring Transparency of State and Local Offices of Inspector General

Inspectors general are the independent government watchdogs tasked with combating fraud, waste, abuse, and corruption, and promoting efficiency and effectiveness of the agencies, programs, and jurisdictions they oversee. Unlike federal inspectors general, state and local inspectors general are not required to adhere to the reporting requirements of the federal Inspector General Act of 1978, which raises questions on their activities. To date, there is limited research on state and local inspectors general given their substantial differences in reporting requirements, content, and publication. The author brings attributes from Stohl’s Information Visibility Scale and the Department of Homeland Security Office of Inspector General Transparency Act to develop a 5-point scale to measure transparency of state and local offices of inspector general. This analysis finds 53% out of 116 state and local offices are very or extremely transparent while the remaining 47% are moderately to not transparent at all. The author recommends amendments to state and local inspector general statutes and their reporting methods to improve transparency within the inspection and oversight profession.

Agile Inverse Design of Polarization-Independent Multi-Functional Reconfiguration Metamaterials Based on Doped VO2.

Increasing attention is being paid to the application potential of multi-functional reconfigurable metamaterials in intelligent communication, sensor networks, homeland security, and other fields. A polarization-independent multi-functional reconfigurable metasurface based on doped vanadium dioxide (VO2) is proposed in this paper. It can be controlled to switch its function among three working modes: electromagnetically induced absorption (EIA), electromagnetically induced transparency (EIT), and asymmetrical absorption. In addition, deep learning tools have greatly accelerated the design of relevant devices. Such devices and the method proposed in this paper have important value in the field of intelligent reconfigurable metamaterials, communication, and sensing.

MBSE Analysis & Update of U.S. Infrastructure Data Taxonomy (IDT) Using U.S. National Critical Functions (NCFs)

AbstractIn this paper, we will demonstrate the application of Model‐Based Systems Engineering (MBSE) tools and techniques we have used to assist the U.S. Department of Homeland Security (DHS) / Cybersecurity Infrastructure Security Agency (CISA) in analysis of open‐source Infrastructure Data Taxonomy (IDT) data to analyze and contribute to the updates required for their IDT. We will show how we have used Functional Analysis, Logical Structure Taxonomies, and MBSE tools to analyze the IDT alongside the DHS National Critical Functions (NCFs) to recommend and improve these updates for their IDT. We have also proposed updates to the NCFs themselves where obvious improvements could be made. Our future recommendations are to continue this effort as a team of INCOSE Critical Infrastructure Protection and Recovery (CIPR) team members, along with other INCOSE Working Groups (WGs), and to explore other use cases based on this model data, as well as inviting other Subject Matter Experts (SMEs) to assist in the enhancements. This modeling effort demonstrated the use of these MBSE tools while working together with other organizations to enable improvements to the Critical Infrastructure (CI) space leveraging systems theory & thought leadership. We will outline further avenues for exploration using this provided MBSE capability in multiple areas that could be useful to the DHS, and will discuss a potential longer‐term engagement with DHS in an annual challenge. This challenge similar to those led by multiple other projects will include collaborations with universities and other CI / CIPR entities interested in this modeling of the CI space. Other opportunities to extend the model further include, but are not limited to security / cybersecurity, operational, and services modeling use cases, involving Industrial Control Systems (ICS) and much more. We have shown how these tools are effective and efficient for use in the water / wastewater sector, but will also yield similar benefits when applied across all identified sectors and across the international community as well (i.e., transportation, telecommunications, etc.). Interestingly we have seen in our initial analyses that the various taxonomies across sectors, subsectors, segments, subsegments, and assets vary slightly between regions and countries internationally for various reasons.

Sr(II) based one-dimensional coordination polymer as an efficient optical sensor for the detection of nitroaromatic explosives in aqueous medium

The detection of explosive materials holds significant importance due to their profound impact on various aspects such as environmental and biological systems, homeland security, and forensic investigations. Metal-organic frameworks (MOFs) and coordination polymers (CPs) have emerged as promising candidates for the selective and sensitive detection of small molecules. In this study, we synthesized a novel oxydiacetic acid functionalized strontium (II) coordination polymer, termed SDGA, using a cost-effective method known as the gel diffusion technique. The crystal structure, characterization, thermal stability, and photoluminescence properties of SDGA were thoroughly investigated by using single crystal X-ray diffraction, FTIR, UV–visible, TG/DTG, and fluorescence spectroscopy. The results revealed that SDGA crystallizes in a monoclinic crystal system with the P21/c space group. SDGA exhibits an emission peak at 340 nm under an excitation wavelength of 301 nm, attributed to the inter-ligand n-π* transition. Leveraging this photoluminescence behaviour, sensing experiments were conducted to detect nitrobenzene and p-nitrophenol within a concentration range of 0-10−20 M. The results indicate a decrease in fluorescence intensity with increasing concentrations of nitrobenzene and p-nitrophenol, indicative of a ‘turn-off’ mechanism.

New Mini Neutron Tubes with Multiple Applications

Recent experimental investigations have demonstrated that a substantial amount of H−/D− ions can be formed by thermal desorption processes. Based on these new findings, new mini axial and coaxial-type neutron tubes have been developed for the production of high or low-energy neutrons via the d-d, d-10B, d-7Li or p-7Li nuclear reactions. By operating these mini neutron tubes with a high frequency AC high-voltage supply, short pulses of high intensity neutron beams can be generated. Multiple applications, such as carbon and well logging, neutron imaging, cancer therapy, medical isotope production, fission reactor start-up, fusion reactor material evaluation, homeland security and space exploration can be performed with the subcompact neutron generator system. It is shown that the performance of these new mini neutron tubes can exceed those of the conventional plasma-based neutron sources.

A versatile internal filtration effect-based ratiometric probe for fluorescence and naked eye sensing of 2,2′,4,4′,6,6′-hexanitrostilbene

2,2′,4,4′,6,6′-hexanitrostilbene (HNS) detection is an essential issue in homeland security screening and environment monitoring. Herein, Mn doped ZnS quantum dots (QDs), ethanolamine (EA) and dansyl hydrazine (DNSH) were proposed as ratiometric probes (DNQDs) for fluorescent (FL), visual FL (VFL), and naked-eye-based visual (NEBV) detection of HNS on surfaces and in water. The amino-HNS complex was formed due to the reaction between HNS and EA after adding HNS into DNQDs. The complex could quench the FL emission of the QDs and DNSH with different rates because of the internal filtration effect. HNS sensing was acquired by comparing the ratio change between their FL intensities. Meanwhile, DNQDs could be used for NEBV sensing of HNS by recognizing the orange-red colored complex. DNQDs demonstrated a good sensitivity: the lowest detectable concentrations/amounts of FL, VFL, and NEBV methods for HNS in water were 0.025, 2.5, and 5 mg/L, and those of VFL and NEBV methods for HNS on surfaces were 0.64 and 1.59 μg/mm2, respectively. Finally, DNQDs were successfully utilized for HNS detection on palm and travel bag surfaces as well as in environmental water. DNQDs-based approaches might be a promising potential for HNS analysis owing to the high sensitivity and versatility.

A native herbaceous community exerts a strong allelopathic effect on the woody range-expander Betula fruticosa

Abstract Biological invasions by alien and range-expanding native plant species can suppress native plants through allelopathy. However, the homeland security hypothesis suggests that some native plants can resist invasion by producing allelopathic compounds that inhibit the growth of invasive plants. Most research has focused on allelopathic interactions between individual native and invasive plant species, with less emphasis on how allelopathy helps entire native communities resist invasions. Additionally, limited knowledge exists about allelopathic interactions between range-expanding native species and recipient native communities, and their influence on invasion success. To bridge this knowledge gap, we conducted two greenhouse competition experiments to test reciprocal allelopathic effects between a native woody range-expanding species, Betula fruticosa, and a community of four native herbaceous species (Sanguisorba officinalis, Gentiana manshurica, Sium suave and Deyeuxia angustifolia) in China. We assessed whether B. fruticosa and the native community differed in their competitive effects and responses, and whether these were influenced by activated carbon, which neutralizes allelochemicals in the soil. Activated carbon reduced the suppressive effects of the native community on the above-ground biomass of B. fruticosa, which indicates that the native community exerted a strong allelopathic effect on B. fruticosa. In contrast, activated carbon only marginally enhanced the suppressive effects of B. fruticosa on the native community, which indicates that allelopathy is not the primary mechanism by which B. fruticosa exerts its suppression. Overall, these findings support the homeland security hypothesis and suggest that biotic resistance from the native herbaceous community may limit the invasion success of the woody range-expander B. fruticosa.

2D material-based surface plasmon resonance biosensors for applications in different domains: an insight.

The design of surface plasmon resonance (SPR) sensors has been greatly enhanced in recent years by the advancements in the production and integration of nanostructures, leading to more compact and efficient devices. There have been reports of novel SPR sensors having distinct nanostructures, either as signal amplification tags like gold nanoparticles (AuNPs) or as sensing substrate-like two-dimensional (2D) materials including graphene, transition metal dichalcogenides (TMDCs), MXene, black phosphorus (BP), metal-organic frameworks (MOFs), and antimonene. Such 2D-based SPR biosensors offer advantages over conventional sensors due to significant increases in their sensitivity with a good figure of merit and limit of detection (LOD). Due to their atomically thin structure, improved sensitivity, and sophisticated functionalization capabilities, 2D materials can open up new possibilities in the field of healthcare, particularly in point-of-care diagnostics, environmental and food monitoring, homeland security protection, clinical diagnosis and treatment, and flexible or transient bioelectronics. The present study articulates an in-depth analysis of the most recent developments in 2D material-based SPR sensor technology. Moreover, in-depth research of 2D materials, their integration with optoelectronic technology for a new sensing platform, and the predicted and experimental outcomes of various excitation approaches are highlighted, along with the principles of SPR biosensors. Furthermore, the review projects the potential prospects and future trends of these emerging materials-based SPR biosensors to advance in clinical diagnosis, healthcare biochemical, and biological applications.

Bright Innovations: Review of Next-Generation Advances in Scintillator Engineering.

This review focuses on modern scintillators, the heart of ionizing radiation detection with applications in medical diagnostics, homeland security, research, and other areas. The conventional method to improve their characteristics, such as light output and timing properties, consists of improving in material composition and doping, etc., which are intrinsic to the material. On the contrary, we review recent advancements in cutting-edge approaches to shape scintillator characteristics via photonic and metamaterial engineering, which are extrinsic and introduce controlled inhomogeneity in the scintillator's surface or volume. The methods to be discussed include improved light out-coupling using photonic crystal (PhC) coating, dielectric architecture modification producing the Purcell effect, and meta-materials engineering based on energy sharing. These approaches help to break traditional bulk scintillators' limitations, e.g., to deal with poor light extraction efficiency from the material due to a typically large refractive index mismatch or improve timing performance compared to bulk materials. In the Outlook section, modern physical phenomena are discussed and suggested as the basis for the next generations of scintillation-based detectors and technology, followed by a brief discussion on cost-effective fabrication techniques that could be scalable.

Beyond Chinese Spy Balloons: Why We Need to Teach East Asian Studies in U.S. Homeland Security and Emergency Preparedness Programs

Abstract This article argues for the inclusion of more East Asia-focused content, particularly regarding China and North Korea, in homeland security and emergency preparedness (HSEP) undergraduate curricula. It contends that current programs overemphasize the post-9/11 counterterrorism paradigm while neglecting state-level threats, especially from China as an ascendant geopolitical rival. China poses multifaceted challenges through cyberattacks, intellectual property theft, economic coercion, and potential military contingencies, such as invading Taiwan. North Korea's nuclear program and cyber activities also jeopardize U.S. homeland security. To prepare future professionals, the article recommends adding a “state actor threats” core subject matter area covering the histories, cultures, and political dynamics underlying these nations’ antagonistic policies. Cultivating deeper cultural competency about U.S. strategic competitors in East Asia is crucial for bolstering national security. Holistic education reform is needed to align HSEP programs with contemporary global geopolitical realities beyond traditional terrorism subjects.

Rapid and reliable ratiometric fluorescence detection of nitro explosive 2,4,6-trinitrophenol based on a near infrared (NIR) luminescent Zn(II)-Nd(III) nanoring

Rapid and quantitative detection of 2,4,6-trinitrophenol (TNP) is very crucial for homeland security, military application, and environment protection. Herein, a nine-metal Zn(II)-Nd(III) nanoring 1 with a diameter of 2.3 nm was constructed by the use of a long-chain Schiff base ligand, which shows ratiometric fluorescence response to TNP with high selectivity and sensitivity. The fluorescence sensing behavior of 1 to TNP is expressed by a first-order equation I1060nm/I560nm = -0.0128*[TNP] + 0.9723, which can be used to quantitatively analyze TNP concentrations in solution. The limits of detection (LODs) to TNP based on the ligand-centered (LC) and Nd(III) emissions of 1 are 5.93 μM and 3.18 μM, respectively. The fluorescence response mechanism to TNP is attributed to the competitive absorption effect and photoinduced electron transfer (PET). The luminescence quenching of 1 is dominated by static process.

A canine model to evaluate the effect of exercise intensity and duration on olfactory detection limits: the running nose.

Detection canines serve critical roles to support the military, homeland security and border protection. Some explosive detection tasks are physically demanding for dogs, and prior research suggests this can lead to a reduction in olfactory detection sensitivity. To further evaluate the effect of exercise intensity on olfactory sensitivity, we developed a novel olfactory paradigm that allowed us to measure olfactory detection thresholds while dogs exercised on a treadmill at two different exercise intensities. Dogs (n = 3) showed a decrement in olfactory detection for 1-bromooctane at 10-3 (v/v) dilutions and lower under greater exercise intensity. Dogs' hit rate for the lowest concentration dropped from 0.87 ± 0.04 when walking at low intensity to below 0.45 ± 0.06 when trotting at moderate intensity. This decline had an interaction with the duration of the session in moderate intensity exercise, whereby dogs performed near 100% detection in the first 10 min of the 8 km/h session, but showed 0% detection after 20 min. Hit rates for high odor concentrations (10-2) were relatively stable at both low (1 ± 0.00) and moderate (0.91 ± 0.04) exercise intensities. The paradigm and apparatus developed here may be useful to help further understand causes of operationally relevant olfactory detection threshold decline in dogs.

Rapid standoff spectroscopic characterization of plastic waste using quartz tuning fork

Standoff molecular identification of chemicals finds immense applications in homeland security, forensic investigation and plastic recycling industries. Although, standoff detection using mid-infrared radiation offers excellent molecular selectivity, sensitive detection of mid-IR radiation using inexpensive detectors is a challenge. In the present work, we show commercially available inexpensive Quartz Tuning Fork (QTF) can be effectively used for rapid standoff detection of solid samples using mid-IR radiation. In this method, a plastic sample placed 40 cm away was excited with tunable infrared (IR) radiation pulsed at the resonance frequency of the QTF. The IR radiation scattered off the plastic sample was used for exciting the QTF into resonance. Plotting the QTF resonant amplitude as a function of irradiating IR wavelength represents the unique IR spectrum of the plastic sample under study. The resolution of spectra recorded using QTF was found to be superior to those collected with ATR-FTIR and the technique based on QTF was 103 times faster than microcantilever-based photothermal deflection techniques. By combining simple machine learning algorithms with QTF standoff resonance IR spectra, various plastic samples can be effectively classified with 100% accuracy. Also, this technique was found to be capable of identifying black plastics without any further sample preparation requirements.

Risk communication and large language models

AbstractThe widespread embrace of Large Language Models (LLMs) integrated with chatbot interfaces, such as ChatGPT, represents a potentially critical moment in the development of risk communication and management. In this article, we consider the implications of the current wave of LLM‐based chat programs for risk communication. We examine ChatGPT‐generated responses to 24 different hazard situations. We compare these responses to guidelines published for public consumption on the US Department of Homeland Security's Ready.gov website. We find that, although ChatGPT did not generate false or misleading responses, ChatGPT responses were typically less than optimal in terms of their similarity to guidances from the federal government. While delivered in an authoritative tone, these responses at times omitted important information and contained points of emphasis that were substantially different than those from Ready.gov. Moving forward, it is critical that researchers and public officials both seek to harness the power of LLMs to inform the public and acknowledge the challenges represented by a potential shift in information flows away from public officials and experts and towards individuals.

Marriage Equality and the Transnational Flow of Skilled Labor: The Impact of Same-Sex Marriage Legalization in the United States on the Inflow of Skilled Labor

This paper examines the impact on skilled labor migration to the United States of same-sex marriage legalization in European countries and US federal recognition of foreign same-sex marriages. Analyzing US Department of Homeland Security data, we find that European legalization decreased skilled labor admissions to the United States by 22 percent, most notably after six years. However, US recognition of foreign same-sex marriages mitigated this effect post-2013, indicating that such legalizations facilitate skilled labor movement between nations.

Implementation of a COVID-19 Closed/Open POD Partnership: A Creative Professional Practice Exemplar for Occupational and Environmental Health Nurses.

For more than 15 years, the U.S. Centers for Disease Control and Prevention has recommended that all community agencies and workplace environments create structured communication and collaborative plans for emergency or disaster events (2008). This recommendation is aligned with the U.S. Department of Homeland Security's (2022) National Infrastructure Protection Plan. The Coronavirus Disease 2019 (COVID-19) pandemic ultimately demonstrated the importance of having organized plans and processes in place for the effective and rapid dispensing of medical countermeasures (MCMs) to the general populace. Occupational and environmental health nurses (OHNs) can utilize examples of successful MCM dispensing programs and adjust details to fit individual organizational needs. This report examines a closed point of dispensing (Closed POD) mass vaccination program as a guide for designing successful workplace partnerships. Closed PODs are public or private sites that have set up a memorandum of understanding (MOU) with local health authorities to dispense MCMs to their populations during a public health emergency. The desired outcome of a closed POD agreement is the facilitation of employee health and safety, as well as enabling workplace continuity of operations. OHNs will play a pivotal role in any future disaster or emergency event. Because OHNs understand the critical need for anticipatory planning, they are in a prime position to drive the creation and implementation of a closed POD partnership between their workplace and their local health department.

Low‐Dimensional Metal Halide for High Performance Scintillators

AbstractInorganic scintillators play a pivotal role in diverse fields like medical imaging, nondestructive detection, homeland security, and high‐energy physics. However, traditional inorganic scintillators encounter challenges such as high fabrication costs and low light yield. Recently, low‐dimensional metal halide scintillators (LDMHS) have witnessed rapid progress, owing to their distinctive crystal structure and superior radioluminescence performance. Herein, an overview of recent advancements and proposed instructive pathways for achieving high‐performance LDMHS is provided. First, the scintillation physical mechanism and emphasis on the essential requirements of scintillators for diverse applications are elucidated. Furthermore, LDMHS are classified according to B‐site cations, and their respective characteristics and recent advancements are introduced. This encompasses the understanding of structure‐property relationships and the routes and rules for optimizing scintillation performance. Finally, the persisting challenges in this burgeoning field and proposed potential research directions for future exploration are discussed.

Assimilation: How Post-9/11 Government Tactics Have Hindered Muslims From Socioeconomic Integration

The devastating attacks of 9/11 left life-changing impacts on how the world viewed national security. The United States, at its epicenter, formally overhauled its government strategies and approaches in assured attempts to prevent such occurrences ever again. Thus, the establishment of the Department of Homeland Security and the implementation of policies reflected new behaviors towards individuals from certain religious or geographic background. While successfully eliminating the recurrence of terrorist attacks of such scale, these extreme approaches vociferosly affected the United States’ Muslim population —many whom have immigrated in pursuit of the ‘American Dream’— from integrating into society. This paper seeks to establish that post-9/11 policies have perpetuated anti-Muslim bias in the minds of the American people, thus impacting the Muslim population’s ability to integrate into society: measured by sections of Milton Gordon’s assimilation theory. Muslim-Americans are vulnerable to unjust constraints or responsibility for the extremist few, all by a governing body established to serve the interests of all its citizens. Studying the extent these tactics have affected Muslim-Americans highlight limitations of the justice system and reveal calls to action where adequate support should be given. Publicly isolating people ties a negative connotation to their existence, which can cause wider society to disassociate themselves from isolated individuals.