Analyzing tiger interaction and home range shifts using a time-geographic approach.

BACKGROUND: Interaction through movement can be used as a marker to understand and model interspecific and intraspecific species dynamics, and the collective behavior of animals sharing the same space. This research leverages the time-geography framework, commonly used in human movement research, to explore the dynamic patterns of interaction between Indochinese tigers (Panthera tigris corbeti) in the western forest complex (WEFCOM) in Thailand. METHODS: We propose and assess ORTEGA, a time-geographic interaction analysis method, to trace spatio-temporal interactions patterns and home range shifts among tigers. Using unique GPS tracking data of tigers in WEFCOM collected over multiple years, concurrent and delayed interaction patterns of tigers are investigated. The outcomes are compared for intraspecific tiger interaction across different genders, relationships, and life stages. Additionally, the performance of ORTEGA is compared to a commonly used proximity-based approach. RESULTS: Among the 67 tracked tigers, 42 show concurrent interactions at shared boundaries. Further investigation of five tigers with overlapping home ranges (two adult females, a male, and two young male tigers) suggests that the mother tiger and her two young mostly stay together before their dispersal but interact less post-dispersal. The male tiger increases encounters with the mother tiger while her young shift their home ranges. On another timeline, the neighbor female tiger mostly avoids the mother tiger. Through these home range dynamics and interaction patterns, we identify four types of interaction among these tigers: following, encounter, latency, and avoidance. Compared to the proximity-based approach, ORTEGA demonstrates better detects concurrent mother-young interactions during pre-dispersal, while the proximity-based approach misses many interactions among the dyads. With larger spatial buffers and temporal windows, the proximity-based approach detects more encounters but may overestimate the duration of interaction. CONCLUSIONS: This research demonstrates the applicability and merits of ORTEGA as a time-geographic based approach to animal movement interaction analysis. We show time geography can develop valuable, data-driven insights about animal behavior and interactions. ORTEGA effectively traces frequent encounters and temporally delayed interactions between animals, without relying on specific spatial and temporal buffers. Future research should integrate contextual and behavioral information to better identify and characterize the nature of species interaction.

Competitive interactions and coexistence of sympatric flagship carnivores in Asia.

Understanding the competition and coexistence of flagship carnivores is key to creating strategies for their conservation in the face of global carnivore declines. Although studies exploring the dynamics and competition between tigers (Panthera tigris) and leopards (P. pardus) span decades, there is a lack of understanding regarding the factors that influence their coexistence mechanisms on a broad scale, as well as the drivers determining their exploitative and interference competition. We gathered a comprehensive list of research papers among which 36 papers explored the interspecific interactions between tigers and leopards and tested the influence of biotic and abiotic factors on the coexistence mechanisms along three dimensions using multiple response variables regression models; we also tested the influence of ecological drivers determining the exploitative or interference competition between tigers and leopards. Elevation and ungulate density were the most important predictors in regulating the coexistence mechanisms. Tigers and leopards exhibited more positive relations/higher overlaps as elevation increased in the spatial niche. In addition, they showed a higher dietary overlap in the prey-rich regions. We determined that interference competition between tigers and leopards was less frequently observed in habitats with dense tree cover and homogeneous vegetation structures. Meanwhile, studies with multiple metrics would promote the detection of interference competition. Our study provides new insight into the competitive interactions and coexistence mechanisms of tigers and leopards on a broad scale. Policy-makers and managers should pay more attention to the factors of elevation, prey abundance, and habitat structures for the conservation of tigers and leopards.

An assessment of bacterial contamination of indirect ophthalmoscopes and condensing lenses used in clinical practice: A multi-center study.

PURPOSE: To investigate bacterial contamination of indirect ophthalmoscopes and condensing lenses used in three UK veterinary referral centers, and the impact of an implemented cleaning protocol. METHODS: Bacteriology samples from 10 indirect ophthalmoscopes and 10 condensing lenses were taken at each center (n = 30 T0), before initiating one of three cleaning frequencies (every 2 weeks/once weekly/daily) for 28 days. The most contaminated indirect ophthalmoscope and condensing lens from each center were re-sampled 30 min prior to (T1; n = 9) and 30 min after (T2; n = 9) the final clean. Sensitivity testing was completed using MIC. RESULTS: Seventy-three isolates representing 15 different bacterial populations (genus/species) were cultured from 36 of 48 (75%) swabs tested. The most frequently cultured isolates were Staphylococcus spp. 30%, Micrococcus 22%, and Bacillus 14%. Pseudomonas aeruginosa, Pantoea, and Staphylococcus pseudintermedius demonstrated resistance to >50% of antibiotics against which they were tested. Eighty-three percent of T0 samples (54 isolates across 11 species, median 2 isolates/swab), all T1 samples (15 isolates across 8 species, median 2 isolates/swab), and 22% of T2 samples (4 isolates across 4 species, median 0 isolates/swab) were contaminated. Head contact points were most contaminated irrespective of time point. A T1 sample was 57 times more likely (95% CI: 2.4-1376) to have a positive culture than a T2 sample (p = .01). CONCLUSIONS: Baseline contamination was high, representing a potential source of nosocomial infection in ophthalmic patients and handlers of diagnostic equipment. No center implemented a cleaning protocol prior to this study. Routine cleaning reduces bacterial contamination.

Addressing the impact of canine distemper spreading on an isolated tiger population in northeast Asia.

The continuation of the isolated Amur tiger (Panthera tigris altaica) population living along the China-Russia border is facing serious challenges due to factors such as its small size (including 38 individuals) and canine distemper virus (CDV). We use a population viability analysis metamodel, which consists of a traditional individual-based demographic model linked to an epidemiological model, to assess options for controlling the impact of negative factors through domestic dog management in protected areas, increasing connectivity to the neighboring large population (including more than 400 individuals), and habitat expansion. Without intervention, under inbreeding depression of 3.14, 6.29, and 12.26 lethal equivalents, our metamodel predicted the extinction within 100 years is 64.4%, 90.6%, and 99.8%, respectively. In addition, the simulation results showed that dog management or habitat expansion independently will not ensure tiger population viability for the next 100 years, and connectivity to the neighboring population would only keep the population size from rapidly declining. However, when the above three conservation scenarios are combined, even at the highest level of 12.26 lethal equivalents inbreeding depression, population size will not decline and the probability of extinction will be <5.8%. Our findings highlight that protecting the Amur tiger necessitates a multifaceted synergistic effort. Our key management recommendations for this population underline the importance of reducing CDV threats and expanding tiger occupancy to its former range in China, but re-establishing habitat connectivity to the neighboring population is an important long-term objective.

Contributions of distemper control and habitat expansion to the Amur leopard viability.

The Amur leopard (Panthera pardus orientalis) is a critically endangered top predator that struggles on the brink of extinction due to threats such as canine distemper virus (CDV), habitat loss, and inbreeding depression. Here we develop a viability analysis metamodel that combines a traditional individual-based demographic model with an epidemiological model to assess the benefits of alternative population management actions in response to multiple distinct threats. Our results showed an extinction risk of 10.3%-99.9% if no management actions were taken over 100 years under different levels of inbreeding depression. Reducing the risk of CDV infection in Amur leopards through the low-coverage vaccination of leopards and the management of sympatric domestic dogs could effectively improve the survival probability of the leopard population, and with habitat expansion added to these management measures, the population expanded further. Our findings highlight that protecting the Amur leopard necessitates a multifaceted synergistic effort, and controlling multiple threats together may significantly escalate overall viability of a species, especially for small-isolated threatened population. More broadly, our modeling framework could offer critical perspectives and scientific support for conservation planning, as well as specific adaptive management actions for endangered species around the world.

Paper spray ionization-high-resolution mass spectrometry (PSI-HRMS) of peroxide explosives in biological matrices.

Mitigation of the peroxide explosive threat, specifically triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD), is a priority among the law enforcement community, as scientists and canine (K9) units are constantly working to improve detection. We propose the use of paper spray ionization-high-resolution mass spectrometry (PSI-HRMS) for detection of peroxide explosives in biological matrices. Occurrence of peroxide explosives and/or their metabolites in biological samples, obtained from urine or blood tests, give scientific evidence of peroxide explosives exposure. PSI-HRMS promote analysis of samples in situ by eliminating laborious sample preparation steps. However, it increases matrix background issues, which were overcome by the formation of multiple alkali metal adducts with the peroxide explosives. Multiple ion formation increases confidence when identifying these peroxide explosives in direct sample analysis. Our previous work examined aspects of TATP metabolism. Herein, we investigate the excretion of a TATP glucuronide conjugate in the urine of bomb-sniffing dogs and demonstrate its detection using PSI from the in vivo sample.

In vitro metabolism of HMTD and blood stability and toxicity of peroxide explosives (TATP and HMTD) in canines and humans.

Triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) are prominent explosive threats. Mitigation of peroxide explosives is a priority among the law enforcement community, with canine (K9) units being trained to recognise the scent of peroxide explosives. Herein, the metabolism, blood distribution, and toxicity of peroxide explosives are investigated.HMTD metabolism studies in liver microsomes identified two potential metabolites, tetramethylene diperoxide diamine alcohol aldehyde (TMDDAA) and tetramethylene peroxide diamine dialcohol dialdehyde (TMPDDD).Blood stability studies in dogs and humans showed that HMTD was rapidly degraded, whereas TATP remained for at least one week.Toxicity studies in dog and human hepatocytes indicated minimum cell death for both TATP and HMTD.

Weights of gaur (Bos gaurus) and banteng (Bos javanicus) killed by tigers in Thailand.

The primary prey of tigers across much of South-East Asia has been depleted, reducing the ability of already limited habitat to support tigers. To better understand the extent to which two of the largest prey species, gaur (Bos gaurus) and banteng (Bos javanicus), contribute to the tiger's diet, we estimated the average size of these species killed by tigers. This information is needed to more accurately calculate biomass of these species in the tiger's diet and to devise strategies to increase tiger carrying capacity where habitat is fragmented and limited in west-central Thailand. We used temporally clumped locations of 24 satellite radio-collared tigers to identify their kill sites and obtained mandibles from 82 gaur and 79 banteng. Kills were aged by teeth eruption sequence, sectioning the M1 molar and counting cementum annuli. Of all gaur killed, 45.2% were adults; of all banteng killed, 55.7% were adults. The average weight of banteng killed was 423.9 kg, which was similar to the 397.9 kg average weight for gaur. The mean weight of both prey species is 3.5-4.5 times greater than the predicted 1:1 preferred prey to predator ratio. In the absence of medium-sized prey, killing these larger animals may be especially critical for female tigers provisioning nearly independent young when male offspring are already larger than the mother. This is the first study to present data on the average weights of gaur and banteng killed in South-East Asia, and these results suggest that these are key prey species to target in tiger prey recovery efforts.

Binge Drinking among Economically Disadvantaged African American Older Adults with Diabetes.

Purpose. This study investigated the effect of demographic, socioeconomic, and psychological factors as well as the role of health determinants on alcohol consumption and binge drinking among economically disadvantaged African American older adults with type 2 diabetes mellites (T2DM). Methods. This survey recruited 231 African Americans who were older adults (age 65+ years) and had T2DM. Participants were selected from economically disadvantaged areas of South Los Angeles. A structured face-to-face interview was conducted to collect data on demographic factors, objective and subjective socioeconomic status (SES) including education and financial difficulty, living arrangement, marital status, health, and drinking behaviors (drinking and binge drinking). Results. Age, gender, living alone, pain, comorbid conditions, and smoking were associated with drinking/binge drinking. Male gender, pain, and being a smoker were associated with higher odds of drinking/binge drinking, while individuals with more comorbid medical conditions had lower odds of binge drinking. Conclusion. In economically constrained urban environments, gender, pain, and smoking but not age, SES, depression, and health may predict binge drinking for African American older adults with T2DM. African Americans older adult men with T2DM with comorbid pain should be screened for binge drinking.

Chronic Respiratory Disease and Health-Related Quality of Life of African American Older Adults in an Economically Disadvantaged Area of Los Angeles.

Background. Most of the attention of policy makers, program planners, clinicians, and researchers in the area of physical health disparities among African American older adults has been traditionally focused on cardiometabolic disease and cancer. Among a long list of chronic medical conditions, chronic respiratory conditions (CRCs), such as asthma, chronic bronchitis, and emphysema, have received less attention. Purpose. This study investigated whether CRCs contribute to physical and mental health-related quality of life (HRQoL) of African American older adults who live in economically disadvantaged urban areas, and whether these effects are due to demographic factors, socioeconomic status (SES), health behaviors, and comorbid medical and mental conditions. Methods. This community-based study recruited 617 African American older adults (age ≥ 65 years) from Service Planning Areas (SPA) 6, an economically disadvantaged area in South Los Angeles. Structured face-to-face interviews were used to collect data on demographic factors (age and gender), SES (educational attainment and financial difficulty), living arrangements, marital status, health behaviors (cigarette smoking and alcohol drinking), health (CRC, number of comorbid medical conditions, depressive symptoms, and pain intensity), and physical and mental HRQoL (Physical and Mental Component Summary Scores; PCS and MCS; SF-12). Linear regressions were used to analyze the data. Results. The presence of CRCs was associated with lower PCS and MCS in bivariate analysis. The association between CRCs and PCS remained significant above and beyond all confounders. However, the association between CRCs and MCS disappeared after controlling for confounders. Conclusion. For African American older adults living in economically disadvantaged urban areas, CRCs contribute to poor physical HRQoL. Evaluation and treatment of CRCs in African American older adults may be a strategy for reduction of disparities in HRQoL in this population. As smoking is the major modifiable risk factor for CRCs, there is a need to increase accessibility of smoking cessation programs in economically disadvantaged urban areas. More research is needed on the types, management, and prognosis of CRCs such as asthma, chronic bronchitis, and emphysema in African American older adults who reside in low-income and resource limited urban areas.

Emergency Department Utilization among Underserved African American Older Adults in South Los Angeles.

Objectives: Using the Andersen's Behavioral Model of Health Services Use, we explored social, behavioral, and health factors that are associated with emergency department (ED) utilization among underserved African American (AA) older adults in one of the most economically disadvantaged urban areas in South Los Angeles, California. Methods: This cross-sectional study recruited a convenience sample of 609 non-institutionalized AA older adults (age ≥ 65 years) from South Los Angeles, California. Participants were interviewed for demographic factors, self-rated health, chronic medication conditions (CMCs), pain, depressive symptoms, access to care, and continuity of care. Outcomes included 1 or 2+ ED visits in the last 12 months. Polynomial regression was used for data analysis. Results: Almost 41% of participants were treated at an ED during the last 12 months. In all, 27% of participants attended an ED once and 14% two or more times. Half of those with 6+ chronic conditions reported being treated at an ED once; one quarter at least twice. Factors that predicted no ED visit were male gender (OR = 0.50, 95% CI = 0.29-0.85), higher continuity of medical care (OR = 1.55, 95% CI = 1.04-2.31), individuals with two CMCs or less (OR = 2.61 (1.03-6.59), second tertile of pain severity (OR = 2.80, 95% CI = 1.36-5.73). Factors that predicted only one ED visit were male gender (OR = 0.45, 95% CI = 0.25-0.82), higher continuity of medical care (OR = 1.39, 95% CI = 1.01-2.15) and second tertile of pain severity (OR = 2.42, 95% CI = 1.13-5.19). Conclusions: This study documented that a lack of continuity of care for individuals with multiple chronic conditions leads to a higher rate of ED presentations. The results are significant given that ED visits may contribute to health disparities among AA older adults. Future research should examine whether case management decreases ED utilization among underserved AA older adults with multiple chronic conditions and/or severe pain. To explore the generalizability of these findings, the study should be repeated in other settings.

Cigarette Smoking among Economically Disadvantaged African-American Older Adults in South Los Angeles: Gender Differences.

The current study aims to explore gender differences in the risk of cigarette smoking among African-American (AA) older adults who live in economically disadvantaged urban areas of southern Los Angeles. This cross-sectional study enrolled 576 older AA adults (age range between 65 and 96 years) who were residing in Service Planning Area 6 (SPA 6), one of the most economically challenged areas in southern Los Angeles. All participants had cardiometabolic disease (CMD). Data were collected using structured face-to-face interviews. Demographic factors (age and gender), socioeconomic status (educational attainment and financial difficulty), health (number of comorbid medical conditions and depressive symptoms), and health behaviors (current alcohol drinking and current smoking) were measured. Logistic regressions were used to analyze the data without and with interaction terms between gender and current drinking, depressive symptoms, and financial difficulty. AA men reported more smoking than AA women (25.3% versus 9.3%; p < 0.05). Drinking showed a stronger association with smoking for AA men than AA women. Depressive symptoms, however, showed stronger effects on smoking for AA women than AA men. Gender did not interact with financial difficulty with regard to current smoking. As AA older men and women differ in psychological and behavioral determinants of cigarette smoking, gender-specific smoking cessation interventions for AA older adults who live in economically deprived urban areas may be more successful than interventions and programs that do not consider gender differences in determinants of smoking. Gender-tailored smoking cessation programs that address drinking for AA men and depression for AA women may help reduce the burden of smoking in AA older adults in economically disadvantaged urban areas. Given the non-random sampling, there is a need for replication of these findings in future studies.

Impact of prey occupancy and other ecological and anthropogenic factors on tiger distribution in Thailand's western forest complex.

Despite conservation efforts, large mammals such as tigers (Panthera tigris) and their main prey, gaur (Bos gaurus), banteng (Bos javanicus), and sambar (Rusa unicolor), are highly threatened and declining across their entire range. The only large viable source population of tigers in mainland Southeast Asia occurs in Thailand's Western Forest Complex (WEFCOM), an approximately 19,000 km2 landscape of 17 contiguous protected areas.We used an occupancy modeling framework, which accounts for imperfect detection, to identify the factors that affect tiger distribution at the approximate scale of a female tiger's home range, 64 km2, and site use at a scale of 1-km2. At the larger scale, we estimated the proportion of sites at WEFCOM that were occupied by tigers; at the finer scale, we identified the key variables that influence site-use and developed a predictive distribution map. At both scales, we examined key anthropogenic and ecological factors that help explain tiger distribution and habitat use, including probabilities of gaur, banteng, and sambar occurrence from a companion study.Occupancy estimated at the 64-km2 scale was primarily influenced by the combined presence of all three large prey species, and 37% or 5,858 km2 of the landscape was predicted to be occupied by tigers. In contrast, site use estimated at the scale of 1 km2 was most strongly influenced by the presence of sambar.By modeling occupancy while accounting for imperfect probability of detection, we established reliable benchmark data on the distribution of tigers in WEFCOM. This study also identified factors that limit tiger distributions; which managers can then target to expand tiger distribution and guide recovery elsewhere in Southeast Asia.

Commentary: Campylobacter and Hemolytic Uremic Syndrome.

There are reports in the literature stating that Campylobacter infections can cause hemolytic uremic syndrome (HUS); however, a mechanism for how Campylobacter induces HUS has not been proposed by investigators. The most common bacterial inducer of HUS is the Shiga toxin-producing Escherichia coli (STEC), and a few cases of HUS are induced by an invasive Shigella dysenteriae or Streptococcus pneumoniae infection. Campylobacter spp. have not been shown to produce Shiga toxin (Stx) nor do they possess genetic elements capable of producing a Stx-like toxin. The neuraminidase associated with pneumococcal HUS has not been observed in Campylobacter. Therefore, in the absence of a well-defined toxic mechanism, it not clear that Campylobacter actually causes HUS.

Genome-Wide Evolutionary Analysis of Natural History and Adaptation in the World's Tigers.

No other species attracts more international resources, public attention, and protracted controversies over its intraspecific taxonomy than the tiger (Panthera tigris) [1, 2]. Today, fewer than 4,000 free-ranging tigers survive, covering only 7% of their historical range, and debates persist over whether they comprise six, five, or two subspecies [3-6]. The lack of consensus over the number of tiger subspecies has partially hindered the global effort to recover the species from the brink of extinction, as both captive breeding and landscape intervention of wild populations increasingly require an explicit delineation of the conservation management units [7]. The recent coalescence to a late Pleistocene bottleneck (circa 110 kya) [5, 8, 9] poses challenges for detecting tiger subspecific morphological traits, suggesting that elucidating intraspecific evolution in the tiger requires analyses at the genomic scale. Here, we present whole-genome sequencing analyses from 32 voucher specimens that resolve six statistically robust monophyletic clades corresponding to extant subspecies, including the recently recognized Malayan tiger (P. tigris jacksoni). The intersubspecies gene flow is very low, corroborating the recognized phylogeographic units. We identified multiple genomic regions that are candidates for identifying the adaptive divergence of subspecies. The body-size-related gene ADH7 appears to have been strongly selected in the Sumatran tiger, perhaps in association with adaptation to the tropical Sunda Islands. The identified genomic signatures provide a solid basis for recognizing appropriate conservation management units in the tiger and can benefit global conservation strategic planning for this charismatic megafauna icon.

Potentially inappropriate medication use among hypertensive older African-American adults.

BACKGROUND: Inappropriate use of medications, particularly among minority older adults with co-morbidity, remains a major public health concern. The American Geriatrics Society (AGS) reports that Potentially Inappropriate Medication (PIM) continues to be prescribed for older adults, despite evidence of poor outcomes. The main objective of this study was to examine the prevalence of PIM use among underserved non-institutionalized hypertensive older African-American adults. Furthermore, this study examines potential correlations between PIM use and the number and type of chronic conditions. METHODS: This cross-sectional study is comprised of a convenience sample of 193 hypertensive non-institutionalized African-American adults, aged 65 years and older recruited from several senior housing units located in underserved areas of South Los Angeles. The updated 2015 AGS Beers Criteria was used to identify participants using PIMs. RESULTS: Almost one out of two participants had inappropriate medication use. While the average number of PIMs taken was 0.87 drugs, the range was from one to seven medications. Almost 23% of PIMs were due to drugs with potential drug-drug interactions. The most common PIM was the use of proton pump inhibitors (PPI) and Central Nervous System (CNS) active agents. Nearly 56% of PIMs potentially increased the risk of falls and fall-associated bone fractures. The use of PIMs was significantly higher among participants who reported a higher number of chronic conditions. Nearly 70% of participants with PIM use reported suffering from chronic pain. CONCLUSIONS: The major reason for high levels of polypharmacy, PIMs, and drug interactions is that patients suffer from multiple chronic conditions. But it may not be possible or necessary to treat all chronic conditions. Therefore, the goals of care should be explicitly reviewed with the patient in order to determine which of the many chronic conditions has the greatest impact on the life goals and/or functional priorities of the patient. Those drugs that have a limited impact on the patient's functional priorities and that may cause harmful drug-drug interactions can be reduced or eliminated, while the remaining medications can focus on the most important functional priorities of the patient.

Using Gas Phase Reactions of Hexamethylene Triperoxide Diamine (HMTD) to Improve Detection in Mass Spectrometry.

Our efforts to lower the detection limits of hexamethylene triperoxide diamine (HMTD) have uncovered previously unreported gas-phase reactions of primary and secondary amines with one of the six methylene carbons. The reaction occurs primarily in the atmospheric pressure chemical ionization (APCI) source and is similar to the behavior of alcohols with HMTD [1]. However, unlike alcohols, the amine reaction conserves the hydrogen peroxide on the intact product. Furthermore, with or without amines, HMTD is oxidized to tetramethylene diperoxide diamine dialdehyde (TMDDD) in a temperature-dependent fashion in the APCI source. Synthesized TMDDD forms very strong adducts (not products) to ammonium and amine ions in the electrospray ionization (ESI) source. Attempts to improve HMTD detection by generating TMDDD in the APCI source with post-column addition of amines were not successful. Signal intensity of the solvent related HMTD product in methanol, [HMTD+MeOH2-H2O2]+ (m/z 207.0975), was understandably related to the amount of methanol in the HMTD environment as it elutes into the source. With conditions optimized for this product, the detection of 100 pg on column was accomplished with a robust analysis of 300 pg (1.44 pmol) routinely performed on the Orbitrap mass spectrometers. Graphical Abstract ᅟ.

Reactions of Organic Peroxides with Alcohols in Atmospheric Pressure Chemical Ionization-the Pitfalls of Quantifying Triacetone Triperoxide (TATP).

Over the last several decades, mass spectrometry has become one of the principle methods for compound identification and quantification. While for analytical purposes, fragments which are not fully characterized in terms of origin and intensity as a function of experimental conditions have been used, understanding the nature of those species is very important. Herein we discuss such issues relative to triacetone triperoxide (TATP) and its frequently observed fragment at m/z 89. This "fragment" has been identified as the gas-phase reaction product of TATP with one or two methanol molecules/ions. Additionally, the origin and conditions of other fragments at m/z 91, 75, and 74 associated with TATP will be addressed. Similar analytical issues associated with other multi-peroxide organic compounds [hexamethylene triperoxide diamine (HMTD), methyl ethyl ketone peroxides (MEKP)] will also be discussed. Solution storage conditions for TATP, HMTD, and tetramethylene diperoxide diamine dialdehyde have been determined. Graphical Abstract ᅟ.

Characterizing the Performance of Pipe Bombs.

Pipe bombs of steel or PVC fragment in reproducible patterns when similarly configured. The power of the explosion correlates with number, mass, and size of the fragments recovered, where a large number of small, low-mass fragments indicate a high-power event and vice versa. In discussing performance, describing pipe fragmentation pattern by fragment weight distribution mapping (FWDM) or fragment surface area distribution mapping (FSADM) was useful. When fillers detonated, detonation velocities of ~4.4 mm/µs were measured. In such cases, side walls of the pipe were thrown first; the average fragment velocity was ~1000 km/s. In deflagrations, the end cap was first thrown; fragment velocities were only ~240 km/s. Blast overpressures varied; at 10 feet, 2 × 12 inch steel pipes containing ~550 g of detonable mixture produced overpressures of 5-6 psi; similar nondetonating pipes produced less than 2 psi. Maximum fragment throw distances were 250-300 m, with an average of ~100 m.

Acetonitrile Ion Suppression in Atmospheric Pressure Ionization Mass Spectrometry.

Efforts to analyze trace levels of cyclic peroxides by liquid chromatography/mass spectrometry gave evidence that acetonitrile suppressed ion formation. Further investigations extended this discovery to ketones, linear peroxides, esters, and possibly many other types of compounds, including triazole and menadione. Direct ionization suppression caused by acetonitrile was observed for multiple adduct types in both electrospray ionization and atmospheric pressure chemical ionization. The addition of only 2% acetonitrile significantly decreased the sensitivity of analyte response. Efforts to identify the mechanism were made using various nitriles. The ion suppression was reduced by substitution of an acetonitrile hydrogen with an electron-withdrawing group, but was exacerbated by electron-donating or steric groups adjacent to the nitrile. Although current theory does not explain this phenomenon, we propose that polar interactions between the various functionalities and the nitrile may be forming neutral aggregates that manifest as ionization suppression. Graphical Abstract ᅟ.