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Cyclotriphosphazene (CP) is a cyclic inorganic compound with the chemical formula N 3 P 3 . This unique molecule consists of a six-membered ring composed of alternating nitrogen and phosphorus atoms, each bonded to two chlorine atoms. CP exhibits remarkable versatility and significance in the realm of materials chemistry due to its easy functionalization via facile nucleophilic substitution reactions in mild conditions as well as intriguing properties of resultant final CP-based molecules or polymers. CP has been served as an important building block for numerous functional materials. This review provides a general and broad overview of the synthesis of CP-based small molecules through nucleophilic substitution of hexachlorocyclotriphosphazene (HCCP), and their applications, including flame retardants, liquid crystals (LC), chemosensors, electronics, biomedical materials, and lubricants, have been summarized and discussed. It would be expected that this review would offer a timely summary of various CP-based materials and hence give an insight into further exploration of CP-based molecules in the future., (© 2024 Wiley-VCH GmbH.)

The electrochemical reduction of nitrogen to produce ammonia is pivotal in modern society due to its environmental friendliness and the substantial influence that ammonia has on food, chemicals, and energy. However, the current electrochemical nitrogen reduction reaction (NRR) mechanism is still imperfect, which seriously impedes the development of NRR. In situ characterization techniques offer insight into the alterations taking place at the electrode/electrolyte interface throughout the NRR process, thereby helping us to explore the NRR mechanism in-depth and ultimately promote the development of efficient catalytic systems for NRR. Herein, we introduce the popular theories and mechanisms of the electrochemical NRR and provide an extensive overview on the application of various in situ characterization approaches for on-site detection of reaction intermediates and catalyst transformations during electrocatalytic NRR processes, including different optical techniques, X-ray-based techniques, electron microscopy, and scanning probe microscopy. Finally, some major challenges and future directions of these in situ techniques are proposed.

A series of conjugated polymers bearing thiophene-based donors and pyromellitic diimide (PMDI) acceptor were prepared, and their electrochromic (EC) properties were studied via using fabricated thin-film EC devices. It was observed that structurally regular alternating polymers with fewer (1 and 2) thiophene donors do not exhibit any EC properties while increasing the number of donors eventually led to the emergence of orange-red-to-green colour switching. On this basis, two more random co-polymers containing higher donor-to-acceptor ratios were synthesized to further improve EC switching properties. The two polymers, which bear a PMDI-to-thiophene ratio of ca. 1 : 7 and 1 : 8, revealed orange red-to-blue colour switching and generally improved optical contrasts and switching speeds in both the visible and near infra-red (NIR) region. In addition, the subtle modulation of polymer colour and hue via variation of the number of thiophene donors was evident through colorimetric study. This work therefore demonstrates the potential and possibility of using the PMDI acceptor unit to construct EC-active conjugated polymers, and considerations for future tuning of colour and switching performances., (© 2024 Wiley-VCH GmbH.)

High-performance electrochromic (EC) and electrofluorochromic (EFC) materials have garnered considerable interest due to their diverse applications in smart windows, optoelectronics, optical displays, military camouflage, etc. While many different EC and EFC polymers have been reported, their preparation often requires multiple steps, and their polymer molecular weights are subjected to batch variation. In this work, we prepared two triphenylamine (TPA)-based and two tetraphenylethylene (TPE)-based derivatives functionalized with terminal styryl groups via direct Suzuki coupling with (4-vinylphenyl)boronic acid and vinylboronic acid pinacol ester. The two novel TPE derivatives exhibited green-yellow aggregation-induced emission (AIE). The EC and EFC properties of pre- and post-thermally treated derivatives spin-coated onto ITO-glass substrates were studied. While all four derivatives showed modest absorption changes with applied voltages up to +2.4 V, retaining a high degree of optical transparency, they exhibited obvious EFC properties with the quenching of blue to yellow fluorescence with I OFF/ON contrast ratios of up to 7.0. The findings therefore demonstrate an elegant approach to preparing optically transparent, heat-induced, cross-linkable styryl-functionalized EFC systems.

Increased use of bioplastics, such as polylactic acid (PLA), helps in reducing greenhouse gas emissions, decreases energy consumption and lowers pollution, but its degradation efficiency has much room for improvement. The degradation rate of electrospun PLA fibers of varying diameters ranging from 0.15 to 1.33 μm is measured during hydrolytic degradation under different pH from 5.5 to 10, and during aerobic biodegradation in seawater supplemented with activated sewage sludge. In hydrolytic conditions, varying PLA fiber diameter had significant influence over percentage weight loss (W %L ), where faster degradation was achieved for PLA fibers with smaller diameter. W %L was greatest for PLA-5 > PLA-12 > PLA-16 > PLA-20, with average W %L at 30.7%, 27.8%, 17.2% and 14.3% respectively. While different pH environment does not have a significant influence on PLA degradation, with W %L only slightly higher for basic environments. Similarly biodegradation displayed faster degradation for small diameter fibers with PLA-5 attaining the highest degree of biodegradation at 22.8% after 90 days. Hydrolytic degradation resulted in no significant structural change, while biodegradation resulted in significant hydroxyl end capping products on the PLA surface. Scanning electron microscopy (SEM) imaging of degraded PLA fibers showed a deteriorated morphology of PLA-5 and PLA-12 fibers with increased adhesion structures and irregularly shaped fibers, while a largely unmodified morphology for PLA-16 and PLA-20., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Converting polystyrene into value-added oxygenated aromatic compounds is an attractive end-of-life upcycling strategy. However, identification of appropriate catalysts often involves laborious and time-consuming empirical screening. Herein, after demonstrating the feasibility of using acridinium salts for upcycling polystyrene into benzoic acid by photoredox catalysis for the first time, we applied low-cost descriptor-based combinatorial in silico screening to predict the photocatalytic performance of a family of potential candidates. Through this approach, we identified a non-intuitive fluorinated acridinium catalyst that outperforms other candidates for converting polystyrene to benzoic acid in useful yields at low catalyst loadings (≤5 mol%). In addition, this catalyst also proved effective with real-life polystyrene waste containing dyes and additives. Our study underscores the potential of computer-aided catalyst design for valorizing polymeric waste into essential chemical feedstock for a more sustainable future., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The discovery of aggregation-induced emission (AIE) phenomenon in 2001 has had a significant impact on materials development across different research disciplines. AIE-active materials have been widely exploited for various applications in optoelectronics, sensing, biomedical, and stimuli-responsive systems, etc. This is made possible by integrating AIE features with other fields of science and engineering, such as nanoscience and nanotechnology. AIE has been extensively employed, particularly for biomedical applications, such as biosensing, bioimaging, and theranostics. However, development of AIE-based nanotechnology for other applications is comparatively less, although there have been increasing research activities in recent years. Given the significance and potential of the marriage between AIE hallmark and nanotechnology in AIE-active materials development, this review article summarizes and showcases the latest research efforts in AIE-based nanomaterials, including nanomaterials synthesis and their nonbiomedical applications, such as sensing, optoelectronics, functional coatings, and stimuli-responsive systems. A perspective on the outlook of AIE-based nanostructured materials and relevant nanotechnology for nonbiomedical applications will be provided, giving an insight into how to design AIE-active nanostructures as well as their applications beyond the biomedical domain.

Hydrochromic materials, which change color in response to moisture, are highly sought-after due to some unique applications such as moisture detection, humidity monitoring, anti-counterfeiting, and sweat-pore mapping. We herein report a new thioxanthene-9-ols/thioxanthylium cations hydrochromic system. The hydrochromic thioxanthylium cations can be generated/regenerated by exposing a chemically stable thioxanthene-9-ol to trifluoroacetic acid (TFA). The intensely colored thioxanthylium cations can be chemically reverted to the colorless thioxanthene-9-ol. Interestingly, the conversion between thioxanthene-9-ol and its cation species was found to be highly reversible in most cases (up to 50 activation-deactivation cycles). The color and moisture-sensitivity of thioxanthylium cations were also validated to be tunable via functionalization of the thioxanthene core with different aliphatic and aromatic groups at its 9 or 2,7-positions. Finally, paper probes were prepared using solution-immersion and inkjet-printing techniques to demonstrate the system's potential applications in humidity sensing and anti-counterfeiting., (© 2022 Wiley-VCH GmbH.)

Transition metal catalysed C-H bond activation chemistry has emerged as an exciting and promising approach in organic synthesis. This allows us to synthesize a wider range of functional molecules and conjugated polymers in a more convenient and more atom economical way. The formation of C-C bonds in the construction of pi-conjugated systems, particularly for conjugated polymers, has benefited much from the advances in C-H bond activation chemistry. Compared to conventional transition-metal catalysed cross-coupling polymerization such as Suzuki and Stille cross-coupling, pre-functionalization of aromatic monomers, such as halogenation, borylation and stannylation, is no longer required for direct arylation polymerization (DArP), which involve C-H/C-X cross-coupling, and oxidative direct arylation polymerization (Ox-DArP), which involves C-H/C-H cross-coupling protocols driven by the activation of monomers' C(sp 2 )-H bonds. Furthermore, poly(annulation) via C-H bond activation chemistry leads to the formation of unique pi-conjugated moieties as part of the polymeric backbone. This review thus summarises advances to date in the synthesis of conjugated polymers utilizing transition metal catalysed C-H bond activation chemistry. A variety of conjugated polymers via DArP including poly(thiophene), thieno[3,4-c]pyrrole-4,6-dione)-containing, fluorenyl-containing, benzothiadiazole-containing and diketopyrrolopyrrole-containing copolymers, were summarized. Conjugated polymers obtained through Ox-DArP were outlined and compared. Furthermore, poly(annulation) using transition metal catalysed C-H bond activation chemistry was also reviewed. In the last part of this review, difficulties and perspective to make use of transition metal catalysed C-H activation polymerization to prepare conjugated polymers were discussed and commented., (© 2021 Wiley-VCH GmbH.)

The recent advancements in thermoelectric materials are largely credited to two factors, namely established physical theories and advanced materials engineering methods. The developments in the physical theories have come a long way from the "phonon glass electron crystal" paradigm to the more recent band convergence and nanostructuring, which consequently results in drastic improvement in the thermoelectric figure of merit value. On the other hand, the progresses in materials fabrication methods and processing technologies have enabled the discovery of new physical mechanisms, hence further facilitating the emergence of high-performance thermoelectric materials. In recent years, many comprehensive review articles are focused on various aspects of thermoelectrics ranging from thermoelectric materials, physical mechanisms and materials process techniques in particular with emphasis on solid state reactions. While bottom-up approaches to obtain thermoelectric materials have widely been employed in thermoelectrics, comprehensive reviews on summarizing such methods are still rare. In this review, we will outline a variety of bottom-up strategies for preparing high-performance thermoelectric materials. In addition, state-of-art, challenges and future opportunities in this domain will be commented.

Using data of 1.4 million non-aggregate, publicly available, private residential property resale transactions for Hong Kong from 1991 to 2015, this paper addresses a public policy question raised by Demsetz from a Coasian angle. It estimates the impact of a less explored but ecologically problematic realm of renovation waste upon change of ownership of property units in a highly commodified property market. The estimate shows the extent and possibly high cost of the government in addressing negative externalities. Informed by the findings, this paper puts forward the recommendation of a prepaid lump sum waste monitoring levy, which is reimbursable upon self-reporting of waste generation. The collected information, when made open to the public, may help market forces to address poor building quality which causes legitimate major renovations and encourage better workmanship for future edifices., Competing Interests: Declaration of Competing Interest The author declares that he has no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In comparison with traditional inorganic electrochromic materials, organic polymers offer advantages such as fast switching speed, flexibility, lightweightness, low cost and nontoxicity, solution-processability, and color tunability. Herein, a series of hyper-branched copolymers are synthesized from triphenylamine and 3,4-ethylenedioxythiophene with different feed ratios via iron(III) chloride (FeCl 3 )-mediated oxidative polymerization. The resultant organic-soluble polymers are easily processable and their corresponding electrochromic devices are found to be stable with limited degradation upon 2500 cycles. In addition to their facile synthesis to achieve solution-processable polymers, studies also show that the polymers exhibit multielectrochromic properties and give rise to five colored states upon oxidative-doping by applying an external voltage between 0 and 2.0 V, providing an interesting example of polymers with unique electrochromic switching among up to five colors, from yellow at the neutral state, to pale green, pale purple, orange, and finally gray., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The increasing prevalence of infectious diseases in recent decades has posed a serious threat to public health. Routes of transmission differ, but the respiratory droplet or airborne route has the greatest potential to disrupt social intercourse, while being amenable to prevention by the humble face mask. Different types of masks give different levels of protection to the user. The ongoing COVID-19 pandemic has even resulted in a global shortage of face masks and the raw materials that go into them, driving individuals to self-produce masks from household items. At the same time, research has been accelerated towards improving the quality and performance of face masks, e.g., by introducing properties such as antimicrobial activity and superhydrophobicity. This review will cover mask-wearing from the public health perspective, the technical details of commercial and home-made masks, and recent advances in mask engineering, disinfection, and materials and discuss the sustainability of mask-wearing and mask production into the future., Competing Interests: The authors declare no conflict of interests., (Copyright © 2020 Ming Hui Chua et al.)

The discovery of the aggregation-induced emission (AIE) phenomenon in the early 2000s not only has overcome persistent challenges caused by traditional aggregation-caused quenching (ACQ), but also has brought about new opportunities for the development of useful functional molecules. Through the years, AIE luminogens (AIEgens) have been widely studied for applications in the areas of biomedical and biological sensing, chemosensing, optoelectronics, and stimuli responsive materials. Particularly in the application of chemosensing, a myriad of novel AIE-based sensors has been developed to detect different neutral molecular, cationic and anionic species, with a rapid detection time, high sensitivity and high selectivity by monitoring fluorescence changes. This review thus summarises the recent development of AIE-based chemosensors for the detection of anionic species, including halides and halide-containing anions, cyanides, and sulphur-, phosphorus- and nitrogen- containing anions, as well as a few other anionic species, such as citrate, lactate and anionic surfactants., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Objective: During the microsurgical clipping of known aneurysms, angiographically occult (AO) aneurysms are sometimes found and treated simultaneously to prevent their growth and protect the patient from future rupture or reoperation. The authors analyzed the incidence, treatment, and outcomes associated with AO aneurysms to determine whether limited surgical exploration around the known aneurysm was safe and justified given the known limitations of diagnostic angiography., Methods: An AO aneurysm was defined as a saccular aneurysm detected using the operative microscope during dissection of a known aneurysm, and not detected on preoperative catheter angiography. A prospective database was retrospectively reviewed to identify patients with AO aneurysms treated microsurgically over a 20-year period., Results: One hundred fifteen AO aneurysms (4.0%) were identified during 2867 distinct craniotomies for aneurysm clipping. The most common locations for AO aneurysms were the middle cerebral artery (60 aneurysms, 54.1%) and the anterior cerebral artery (20 aneurysms, 18.0%). Fifty-six AO aneurysms (50.5%) were located on the same artery as the known saccular aneurysm. Most AO aneurysms (95.5%) were clipped and there was no attributed morbidity. The most common causes of failed angiographic detection were superimposition of a large aneurysm (type 1, 30.6%), a small aneurysm (type 2, 18.9%), or an adjacent normal artery (type 3, 36.9%). Multivariate analysis identified multiple known aneurysms (odds ratio [OR] 3.45, 95% confidence interval [CI] 2.16-5.49, p < 0.0001) and young age (OR 0.981, 95% CI 0.965-0.997, p = 0.0226) as independent predictors of AO aneurysms., Conclusions: Meticulous inspection of common aneurysm sites within the surgical field will identify AO aneurysms during microsurgical dissection of another known aneurysm. Simultaneous identification and treatment of these additional undiagnosed aneurysms can spare patients later rupture or reoperation, particularly in those with multiple known aneurysms and a history of subarachnoid hemorrhage. Limited microsurgical exploration around a known aneurysm can be performed safely without additional morbidity.

Electroluminochromism is an interesting property found in certain classes of molecules and polymers whose photoluminescence can be modulated through the application of an external electrical bias. Unlike electrochromic materials, electroluminochromic counterparts and their applications are comparatively fewer in quantity and are less established. Nonetheless, there prevails an increasing interest in this class of electro-active materials due to their potential applications in optoelectronics, such as smart-displays, and chemical and biological sensing. This review seeks to showcase the different classes of electroluminochromic materials with focus on (i) organic molecules, (ii) transition metal complexes, and (iii) organic polymers. The mechanisms and electroluminochromic performance of these classes of materials are summarized. This review should allow scientists to have a better and deeper understanding of materials design strategies and, more importantly, structure-property relationships and, thus, develops electroluminochromic materials with desired performance in the future.

Objective: In recent years, delivery of cost-effective "essential neurosurgery" in resource-limited communities has been recognized as an indispensable part of health care and a global health priority. The aim of this study was to review outcomes from operative management of spine trauma at a resource-limited government hospital in Phnom Penh, Cambodia, and to provide an epidemiologic report to guide prevention programs., Methods: A retrospective review of a prospective neurosurgical database was performed to identify risk factors for spine trauma and severe spinal cord injury (American Spinal Injury Association A or American Spinal Injury Association B) and to evaluate the cost-effectiveness of surgery for patients treated at Preah Kossamak Hospital for subaxial and thoracolumbar spine trauma from 2013 to 2016., Results: Surgical treatment was provided to 277 patients with cervical or thoracolumbar spine trauma, including 36 facet dislocations and 135 thoracolumbar burst fractures at a cost of $100-$280 per surgery. Six patients (2.2%) required treatment for postoperative wound infection. Reoperation was performed in 8 patients (2.9%) for wrong-level surgery. Failure of short-segment pedicle screw fixation was discovered in 4 patients (7.0%). Neurologic improvement was reported by 64 patients (65.3%) with incomplete spinal cord injury and available long-term follow-up., Conclusions: Affordable neurosurgical care can be provided in a safe and sustainable manner to patients with traumatic spine and spinal cord injuries in resource-limited communities. This supports the call for essential neurosurgery to be made available around the world to individuals from all socioeconomic strata., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Two stable boron dipyrromethene (BODIPY)-based antiaromatic macrocycles, Mc-Fur and Mc-Th, were synthesized through a one-pot Knoevenagel condensation reaction between a BODIPY precursor and furan-2,5-dicarboxaldehyde or thiophene-2,5-dicarboxaldehyde, respectively. 1 H NMR spectroscopic characterization of the two macrocycles supported their highly antiaromatic character. The oxidation properties of the two macrocycles were studied through electron spin resonance spectroscopy and UV/Vis absorption spectrophotometry, which suggested the formation of a stable monoradical cation species on first oxidation followed by an aromatic dicationic species on subsequent oxidation. Both molecules have a nearly planar π-conjugated backbone and show a strong tendency to aggregate in solution due to efficient stacking of the antiaromatic macrocycles. Transient absorption and two-photon absorption (TPA) measurements in solution and aggregated states of the macrocycles revealed that aggregation resulted in large enhancement of TPA cross sections and increased excited-state lifetimes, in accordance with the decrease in the antiaromatic character in the aggregated state., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

OBJECTIVE Renin-angiotensin system (RAS) genetic polymorphisms are thought to play a role in cerebral aneurysm formation and rupture. The Cerebral Aneurysm Renin-Angiotensin System (CARAS) study prospectively evaluated common RAS polymorphisms and their relation to aneurysmal subarachnoid hemorrhage (aSAH). METHODS The CARAS study prospectively enrolled aSAH patients and controls at 2 academic centers in the United States. A blood sample was obtained from all patients for genetic evaluation and measurement of plasma angiotensin-converting enzyme (ACE) concentration. Common RAS polymorphisms were detected using 5' exonuclease (TaqMan) genotyping assays and restriction fragment length polymorphism analysis. RESULTS Two hundred forty-eight patients were screened, and 149 aSAH patients and 50 controls were available for analysis. There was a recessive effect of the C allele of the angiotensinogen ( AGT) C/T single-nucleotide polymorphism (SNP) (OR 1.94, 95% CI 0.912-4.12, p = 0.0853) and a dominant effect of the G allele of the angiotensin II receptor Type 2 ( AT2) G/A SNP (OR 2.11, 95% CI 0.972-4.57, p = 0.0590) on aSAH that did not reach statistical significance after adjustment for potential confounders. The ACE level was significantly lower in aSAH patients with the II genotype (17.6 ± 8.0 U/L) as compared with the ID (22.5 ± 12.1 U/L) and DD genotypes (26.6 ± 14.2 U/L) (p = 0.0195). CONCLUSIONS The AGT C/T and AT2 G/A polymorphisms were not significantly associated with aSAH after controlling for potential confounders. However, a strong trend was identified for a dominant effect of the G allele of the AT2 G/A SNP. Downregulation of the local RAS may contribute to the formation of cerebral aneurysms and subsequent presentation with aSAH. Further studies are required to elucidate the relevant pathophysiology and its potential implication in treatment of patients with aSAH.

Background: The molecular mechanisms underlying cerebral vasospasm and delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) are incompletely understood. We hypothesized that circulating antiangiogenic factors, such as soluble Fms-like tyrosine kinase 1 (sFlt-1) and soluble transforming growth factor β coreceptor, soluble endoglin (sEng), are important markers of their pathophysiology., Methods: We performed a prospective study in patients with aSAH and measured cerebrospinal fluid and serum levels of sFlt-1 and sEng on postbleed day 1 and 6 and correlated levels with incidence and severity of cerebral vasospasm and DCI., Results: Twenty-seven patients with aSAH were enrolled in the study. Severe angiographic vasospasm was present in 14.8% of patients and DCI occurred in 33.3%. Serum sFlt1 levels were increased on postbleed day 6 in patients who developed vasospasm. However, on postbleed day 1, there were no differences in patients who developed vasospasm. Increased serum sFlt-1 levels on postbleed day 1 were found to predict the development of severe angiographic vasospasm with an area under the curve of 0.818 with an optimal cutoff value of 95 pg/mL. Alterations in sFlt1 were not associated with DCI. Serum and cerebrospinal fluid sEng levels did not correlate with vasospasm or DCI., Conclusions: Serum levels of sFlt-1 are increased in patients with aSAH who are at risk for severe vasospasm. Further studies with larger sample sizes are needed to evaluate whether sFlt-1 levels may predict onset of severe vasospasm and DCI., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Stent-assisted coil embolization and flow diversion with the Pipeline embolization device (PED) are both effective endovascular treatment options for ophthalmic segment aneurysms (OSAs) of the internal carotid artery. Here we present a large comparative cohort study., Methods: A multicenter, retrospective cohort comparison study of consecutively treated OSAs was conducted at 2 academic institutions in the United States comparing stent-coiling (between 2007 and 2015) and PED (between 2011 and 2016)., Results: A total of 62 of OSAs were treated with stent-coiling and 106 were treated with the PED. The stent-coiling-treated aneurysms were larger, although the maximum diameter was not significantly different between the 2 groups (P = 0.05). The median duration of follow-up was 22.5 months for the stent-coiling group and 8.7 months for the PED group (P = 0.0002). Complete occlusion at last follow-up was achieved in 75.9% of aneurysms in the stent-coiling group and in 81.1% of aneurysms in the PED group (P = 0.516). The retreatment rate was higher with stent-coiling, but the difference did not reach statistical significance (P = 0.062). A good functional outcome was achieved in 96.6% of patients in the stent-coiling group and in 94.7% of those in the PED group (P = 0.707). The rate of neurologic complications was 4.8% in the stent-coiling group and 9.4% in the PED group (P = 0.376)., Conclusion: Stent-coiling and the PED were equally effective for treating OSAs. There were no significant differences in terms of procedural complications, angiographic, functional, and visual outcomes. PED may be more favorable for multiple adjacent OSAs., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Here we utilized new diagnostic tools in time-dependent density functional theory to explain the trend of intersystem crossing in benzo(bis)-X-diazole based donor-acceptor-donor type molecules. These molecules display a wide range of fluorescence quantum yields and triplet yields, making them excellent candidates for testing the validity of these diagnostic tools. We believe that these tools are cost-effective and can be applied to structurally similar organic chromophores to predict/explain the trends of intersystem crossing, and thus fluorescence quantum yields and triplet yields without the use of complex and expensive multireference configuration interaction or multireference pertubation theory methods.

OBJECTIVE Delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH) occurs in approximately 30% of patients. The Practical Risk Chart was developed to predict DCI based on admission characteristics; the authors seek to externally validate and critically appraise this prediction tool. METHODS A prospective cohort of aSAH patients was used to externally validate the previously published Practical Risk Chart. The model consists of 4 variables: clinical condition on admission, amount of cisternal and intraventricular blood on CT, and age. External validity was assessed using logistic regression. Model discrimination was evaluated using the area under the receiver operating characteristic curve (AUC). RESULTS In a cohort of 125 patients with aSAH, the Practical Risk Chart adequately predicted DCI, with an AUC of 0.66 (95% CI 0.55-0.77). Clinical grade on admission and amount of intracranial blood on CT were the strongest predictors of DCI and clinical vasospasm. The best-fit model used a combination of the Hunt and Hess grade and the modified Fisher scale to yield an AUC of 0.76 (95% CI 0.675-0.85) and 0.70 (95% CI 0.602-0.8) for the prediction of DCI and clinical vasospasm, respectively. CONCLUSIONS The Practical Risk Chart adequately predicts the risk of DCI following aSAH. However, the best-fit model represents a simpler stratification scheme, using only the Hunt and Hess grade and the modified Fisher scale, and produces a comparable AUC.

OBJECTIVE Renin-angiotensin system (RAS) genetic polymorphisms are thought to play a role in cerebral aneurysm formation and rupture. The Cerebral Aneurysm Renin Angiotensin System (CARAS) study prospectively evaluated associations of common RAS polymorphisms and clinical course after aneurysmal subarachnoid hemorrhage (aSAH). METHODS The CARAS study prospectively enrolled aSAH patients at 2 academic centers in the United States. A blood sample was obtained from all patients for genetic evaluation and measurement of plasma angiotensin converting enzyme (ACE) concentration. Common RAS polymorphisms were detected using 5'exonuclease genotyping assays and pyrosequencing. Analysis of associations of RAS polymorphisms and clinical course after aSAH were performed. RESULTS A total of 166 patients were screened, and 149 aSAH patients were included for analysis. A recessive effect of allele I (insertion) of the ACE I/D (insertion/deletion) polymorphism was identified for Hunt and Hess grade in all patients (OR 2.76, 95% CI 1.17-6.50; p = 0.0206) with subsequent poor functional outcome. There was a similar effect on delayed cerebral ischemia (DCI) in patients 55 years or younger (OR 3.63, 95% CI 1.04-12.7; p = 0.0439). In patients older than 55 years, there was a recessive effect of allele A of the angiotensin II receptor Type 2 (AT2) A/C single nucleotide polymorphism (SNP) on DCI (OR 4.70, 95% CI 1.43-15.4; p = 0.0111). CONCLUSIONS Both the ACE I/D polymorphism and the AT2 A/C single nucleotide polymorphism were associated with an age-dependent risk of delayed cerebral ischemia, whereas only the ACE I/D polymorphism was associated with poor clinical grade at presentation. Further studies are required to elucidate the relevant pathophysiology and its potential implication in the treatment of patients with aSAH.

Background: To date, the use of the flow-diverting Pipeline Embolization Device (PED) for small intracranial aneurysms (≤ 7 mm) has been reported only in single-center series., Objective: To evaluate the safety and efficacy of the PED in a multicenter cohort., Methods: Five major academic institutions in the United States provided data on patient demographics, aneurysm features, and treatment characteristics of consecutive patients with aneurysms ≤ 7 mm treated with a PED between 2009 and 2015. Radiographic outcome was assessed with digital subtraction angiography. Clinical outcome was measured with the modified Rankin Scale., Results: The cumulative number of aneurysms ≤ 7 mm treated with PED at the 5 institutions was 149 in 117 patients (age, 54 years [range, 29-87 years]; male to female, 1-5.9). Aneurysms were most commonly located in the paraophthalmic segment (67.1%) of the internal carotid artery. Radiographic outcome at last follow-up was available for 123 aneurysms (82.6%), with a complete occlusion rate of 87%. Thromboembolic and symptomatic procedural complications occurred in 8.7% and 6% of the aneurysms treated, respectively. There was 1 mortality (0.9%) unrelated to the PED procedure. Multivariable logistic regression identified size < 4 mm, balloon angioplasty to open the device, and simultaneous treatment of multiple aneurysms as predictors of procedural complications. Good clinical outcome was achieved in 96% of electively treated patients., Conclusion: In the largest series on PED for small aneurysms to date, data suggest that treatment with the flow-diverting PED is safe and efficacious, with complication rates comparable to those for traditional endovascular techniques., (Copyright © 2016 by the Congress of Neurological Surgeons)

Background: In an era of continued advancements in endovascular treatment of cerebral aneurysms, novel developments concerning microsurgical clipping are sparse. The Lazic aneurysm clip system represents such an advancement. The applier has a malleable shaft and is designed to minimally obstruct the view of the surgical field. The purpose of this study was to illustrate the transition to this new aneurysm clip system in an established cerebrovascular practice., Methods: We retrospectively reviewed all aneurysms treated with microsurgical clipping using the Lazic aneurysm clip system in 1 cerebrovascular practice in the United States from January 2009 to June 2016., Results: Between 2009 and 2016, a total of 973 aneurysms underwent surgical clipping. The Lazic clip system was used in 191 (19.6%) aneurysms (maximum diameter, 5.6 ± 3.8 mm) in 181 patients. The middle cerebral artery was the most frequent location (25.7%) followed by posterior communicating artery (20.9%). There was a continuous increase in the percentage of aneurysms treated with the Lazic clip system from 6% in 2009 to 98% in 2016. The proportion of posterior circulation aneurysms treated with Lazic clips decreased, whereas the middle cerebral artery location increased. There were a total of 11 complications (5.8%), but no instances of clip malfunction., Conclusions: In the largest series to date, the Lazic clip system proved to be safe and efficacious and presents an interesting alternative to established aneurysm clip systems. This study illustrates the transition of an established cerebrovascular practice to the Lazic clip system., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Moyamoya disease is a vascular disorder characterized by progressive stenosis of the internal carotid artery. The presentation, progression, treatment options, and post-operative clinical outcomes for elderly (60 and older) Moyamoya patients have never been reported., Methods: A retrospective analysis of all patients who were diagnosed with Moyamoya disease by the senior authors between 1991 and 2016 was performed. Patients who were 60 years or older at the time of surgery or last follow-up were further evaluated., Results: Seventy patients were diagnosed with probable or definite Moyamoya disease during the study period (1991-2016). Eight patients (11.4 %; six females: two males; median age 63; range, 60-71 years) were found to be 60 years or older at the time of surgery or last follow-up and were included in the study. All patients had a modified Rankin scale (mRS) of either one or two (median 1) pre-operatively. Six patients (75 %) underwent surgical treatment on a total on seven hemispheres. Post-surgery, one patient had an improved mRS score, three had no changes, and two had worsening in their mRS scores. Both patients who did not undergo surgical interventions suffered from intra-parenchymal hemorrhages post-diagnosis., Conclusions: Moyamoya disease is most commonly seen in young and middle-aged patients. Presentation in the elderly (defined as 60 years and older in this study) is rare, and has never been reported in the literature. In this study, both direct and indirect revascularization procedures demonstrated potential benefit in some of these patients, with stabilization of progressive symptoms.

OBJECTIVE Contemporary treatment for paraophthalmic artery aneurysms includes flow diversion utilizing the Pipeline Embolization Device (PED). Little is known, however, about the potential implications of the anatomical relationship of the ophthalmic artery (OA) origin and aneurysm, especially in smaller aneurysms. METHODS Four major academic institutions in the United States provided data on small paraophthalmic aneurysms (≤ 7 mm) that were treated with PED between 2009 and 2015. The anatomical relationship of OA origin and aneurysm, radiographic outcomes of aneurysm occlusion, and patency of the OA were assessed using digital subtraction angiography. OA origin was classified as follows: Type 1, OA separate from the aneurysm; Type 2, OA from the aneurysm neck; and Type 3, OA from the aneurysm dome. Clinical outcome was assessed using the modified Rankin Scale, and visual deficits were categorized as transient or permanent. RESULTS The cumulative number of small paraophthalmic aneurysms treated with PED between 2009 and 2015 at the 4 participating institutions was 69 in 52 patients (54.1 ± 13.7 years of age) with a male-to-female ratio of 1:12. The distribution of OA origin was 72.5% for Type 1, 17.4% for Type 2, and 10.1% for Type 3. Radiographic outcome at the last follow-up (median 11.5 months) was available for 54 aneurysms (78.3%) with complete, near-complete, and incomplete occlusion rates of 81.5%, 5.6%, and 12.9%, respectively. Two aneurysms (3%) resulted in transient visual deficits, and no patient experienced a permanent visual deficit. At the last follow-up, the OA was patent in 96.8% of treated aneurysms. Type 3 OA origin was associated with a lower rate of complete aneurysm occlusion (p = 0.0297), demonstrating a trend toward visual deficits (p = 0.0797) and a lower rate of OA patency (p = 0.0783). CONCLUSIONS Pipeline embolization treatment of small paraophthalmic aneurysms is safe and effective. An aneurysm where the OA arises from the aneurysm dome may be associated with lower rates of aneurysm occlusion, OA patency, and higher rates of transient visual deficits.

Mono-TPE modified POSS molecules, in which the flexible spacers between TPE and POSS moieties control their self-assembly and aggregation, exhibit a unique unadulterated monomer emission in organic solvents as well as an AIE emission in THF/water.

Background: Unruptured intracranial aneurysms (UIAs) are being detected and treated with endovascular techniques at an increasing rate, with little evidence on the optimal imaging follow-up protocol. We performed a survey of academic neurovascular centers in the United States to assess imaging follow-up strategies and costs after endovascular treatment of UIAs., Methods: An online survey on 5-year follow-up strategies of UIAs treated with endovascular techniques was distributed to neurovascular directors of 101 academic neurovascular centers using the American Association of Neurological Surgeons/Congress of Neurological Surgeons Joint Cerebrovascular Section database. An online healthcare marketplace, NewChoiceHealth, was used to calculate costs., Results: Of 33 (32.7%) institutions that responded to the survey, 26 (25.7%) provided data suitable for analysis. Nine (34.6%), 10 (38.5%), 4 (15.4%), and 3 (11.5%) centers were located in the northeastern, southern, midwestern, and western regions of the United States. Total costs of 5-year follow-up imaging after primary coil embolization and stent-assisted coiling procedures were $3391-$32,882. Costs for aneurysms treated with flow diversion were $2788-$46,670. Eighteen (69.2%) institutions performed cerebral angiography at 6-month follow-up after coil embolization and stent-assisted coiling, and 19 (73.1%) institutions performed cerebral angiography 6 months after flow diversion. Of institutions, 20% affirmed that they maintained an identical imaging follow-up regimen after treatment of ruptured aneurysms., Conclusions: There is significant heterogeneity in imaging follow-up strategies and their associated costs. Stratification of patients by risk of recanalization and corresponding adjustment of follow-up imaging may be 1 strategy to limit unnecessary imaging and control costs., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Curative transarterial embolization of noncavernous sinus dural arteriovenous fistulas (dAVFs) is challenging. We sought to evaluate the role of the middle meningeal artery (MMA) in endovascular treatment of these lesions. We performed a retrospective cohort study on patients who underwent transarterial Onyx embolization of a noncavernous sinus dAVFs with contribution from the MMA at a major academic institution in the United States from January 2009 to January 2015. Twenty consecutive patients who underwent transarterial Onyx embolization of a noncavernous sinus dAVF were identified. One patient was excluded as there was no MMA contribution to the dAVF. All of the remaining 19 patients (61.3 ± 13.8 years of age) underwent transarterial embolization through the MMA. Six patients (31.6%) presented with intraparenchymal or subarachnoid hemorrhage from the dAVF. The overall angiographic cure rate was 73.7% upon last follow up. In 71.4% of successfully treated patients transarterial embolization of the MMA alone was sufficient to achieve angiographic cure. When robust MMA supply was present, MMA embolization resulted in angiographic cure even after embolization of other arterial feeders had failed in 92.9% of patients. A robust contribution of the MMA to the fistula was the single most important predictor for successful embolization (P = 0.00129). We attribute our findings to the fairly straight, non-tortuous course of the MMA that facilitates microcatheter access, navigation, and Onyx penetration. Noncavernous sinus dAVF can be successfully embolized with transarterial Onyx through the MMA, as long as supply is robust. A transvenous approach is rarely necessary. Clin. Anat. 29:718-728, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Objective: Neurologic condition at presentation is the most important predictor of morbidity and mortality from aneurysmal subarachnoid hemorrhage (aSAH). To guide management, it is important to identify patients who are at risk of presenting in poor neurologic condition after aSAH., Methods: We retrospectively reviewed medical records and imaging studies for 387 consecutive cases of aSAH that were managed at a major academic neurovascular center in the United States from January 2008 to December 2013. Clinically accessible patient and aneurysm characteristics were evaluated by univariable analysis and multivariable logistic regression to identify predictors of poor neurologic status at presentation., Results: For all aneurysms, multivariable logistic regression identified age (odds ratio [OR], 1.02; 95% confidence interval [CI], 1.00-1.04; P = 0.0129), aneurysm size (≥7 and <10 mm: OR, 1.78; 95% CI, 1.02-3.11; P = 0.0429; ≥10 mm: OR, 3.22; 95% CI, 1.82-5.70; P < 0.0001), and vertebrobasilar junction location (OR, 10.1; 95% CI, 1.93-52.5; P = 0.0060) as independent predictors of poor neurologic condition at presentation. For internal carotid artery (ICA) aneurysms, female gender (OR, 9.21; 95% CI, 1.54-55.1; P = 0.0151), hypertension (OR, 8.67; 95% CI, 1.80-41.7; P = 0.007), and size ≥7 mm (OR, 3.67; 95% CI, 0.852-15.8; P = 0.0807) were predictive of poor neurologic condition at presentation, with a C statistic of 0.842. No association was found between poor neurologic grade at presentation and smoking status or warfarin therapy., Conclusions: Independent predictors of poor neurologic grade were identified for all, ICA, anterior cerebral artery/anterior communicating artery, middle cerebral artery, and posterior circulation aneurysms. A risk prediction chart was constructed using clinically accessible patient and aneurysm characteristics for poor presenting neurologic condition after ICA aneurysm rupture. These factors should be considered when counseling patients with unruptured intracranial aneurysms., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background and Purpose: Despite rapid advancements in intracranial aneurysm management, there is no evidence as of yet that this has translated into improvement in overall prognosis., Methods: We compared 2 periods of aneurysm management, 1998 to 2003 (n=1023 aneurysms) and 2007 to 2013 (n=1499 aneurysms), at a single, high-volume neurovascular center. Our outcome of interest was low or moderate disability (Glasgow Outcome Scale score of 4 or 5) at 6 months or more post treatment., Results: There were significant improvements in outcome for surgical, endovascular, and overall treatment of unruptured (adjusted odds ratio [OR], 2.33; P=0.0091; adjusted OR, 4.40; P=0.0271; and adjusted OR, 2.58; P=0.0008, respectively) and ruptured (adjusted OR, 3.18; P=0.0004; adjusted OR, 3.54; P=0.0001; and adjusted OR, 3.11; P<0.0001, respectively) aneurysms from the first to the second time period. In 2007 to 2013, the proportion of cases with low or moderate disability at 6 months post subarachnoid hemorrhage was 75.6% for surgical clipping and 76.6% for endovascular therapy., Conclusions: We report significantly improved outcomes over time for overall aneurysm management and for multiple patient subgroups, associated with increased usage of endovascular therapy., (© 2016 American Heart Association, Inc.)

The straightforward synthesis of 3,5-di(triphenylethylenyl) BODIPYs 1-3 from the condensation of 2-(triphenylethylenyl) pyrrole with aryl aldehydes are surprisingly found to produce side products that are hydrogenated at one of the two triphenylethylene substituents. It was also observed that the subsequent Scholl type reaction of 1 resulted in a "1,2-migratory shift" of one triphenylethylene substituent in addition to a ring closing reaction. Preliminary investigations, including DFT calculations and isolation of intermediates, were conducted to study these unusual observations on BODIPY chemistry.

Three meso-ester boron dipyrromethene (BODIPY) dyes have been synthesized and functionalized with aggregation-induced emission (AIE)-active tetraphenylethene or triphenylethene moieties. It was found that functionalizing at the different positions of the BODIPY core resulted in the final dye having different emission properties in response to aggregation: from aggregation-induced quenching (ACQ) to being AIE active. X-ray crystallographic analysis was thus performed to provide an explanation for these differences., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: With increasing use of endovascular techniques in the treatment of ruptured and unruptured aneurysms, the issue of obliteration efficacy has become increasingly important. We have previously reported the Aneurysm Recanalization Stratification Scale, which uses accessible predictors including aneurysm-specific factors (size, rupture, and intraluminal thrombosis) and treatment-related features (treatment modality and immediate angiographic result) to predict retreatment risk after endovascular therapy., Objective: To assess the external validity of the Aneurysm Recanalization Stratification Scale., Methods: External validity was assessed in independent cohorts from 4 centers in the United States and Canada where endovascular and open neurovascular procedures are performed, and in a multicenter cohort of 1543 patients. Probability of retreatment stratified by risk score was derived for each center and the combined multicenter cohort., Results: Despite moderate variability in retreatment rate among centers (29.5%, 9.9%, 9.6%, 26.3%, 19.7%, and 18.3%), the Aneurysm Recanalization Stratification Scale demonstrated good predictive value with C-statistics of 0.799, 0.943, 0.780, 0.695, 0.755, and 0.719 for each center and the combined cohort, respectively. Probability of retreatment stratified by risk score for the combined cohort is as follows: -2, 4.9%; -1, 5.7%; 0, 5.8%; 1, 13.1%; 2, 19.2%; 3, 34.9%; 4, 32.7%; 5, 73.2%; 6, 89.5%; and 7, 100.0%., Conclusion: Surgical decision-making and patient-centered informed consent require comprehensive and accessible information on treatment efficacy. The Aneurysm Recanalization Stratification Scale is a valid prognostic index. This is the first comprehensive model that has been developed to quantitatively predict retreatment risk following endovascular therapy.

OBJECT Pediatric patients with sickle cell disease (SCD) and moyamoya syndrome (MMS) are at significant risk for cerebrovascular accidents despite chronic transfusion therapy. Encephaloduroarteriosynangiosis (EDAS) and encephalomyoarteriosynangiosis (EMAS) are additional therapeutic options for these patients. To date, the incidence of complications after and efficacy of EDAS and EMAS in stroke prevention in this population have been described in several institutional case series reports, but no randomized prospective trials have been reported. METHODS The authors retrospectively reviewed the cases of all pediatric patients at the University of Alabama at Birmingham with a history of homozygous hemoglobin S (HbS) and sickle cell/β-thalassemia (SB0 thalassemia) and on chronic transfusion therapy, including 14 patients with MMS who underwent EDAS or EMAS. RESULTS Sixty-two patients with SCD and on chronic transfusion therapy were identified. After exclusion of patients on chronic transfusion therapy for indications other than stroke prevention, 48 patients (77.4%) remained. Of those patients, 14 (29.1%) underwent EDAS or EMAS. Nine (18.8%) and 25 (52.1%) patients were on chronic transfusion therapy for primary or secondary stroke prevention, respectively, but did not undergo EDAS or EMAS. The 14 patients with SCD and radiological evidence of MMS and on chronic transfusion therapy for primary or secondary stroke prevention underwent 21 EDAS or EMAS procedures for progressive vascular disease (92.9% of patients), stroke (71.4%), and/or seizure (7.1%). The mean (± SD) time from initiation of chronic transfusion therapy to EDAS or EMAS was 76.8 ± 58.8 months. Complications included 1 perioperative stroke, 1 symptomatic subdural hygroma, 1 postoperative seizure, and 1 case of intraoperative cerebral edema that required subsequent cranioplasty. Before EDAS or EMAS, the stroke rate was calculated to be 1 stroke per 7.8 patient-years. One additional stroke occurred during the follow-up period (mean follow-up time 33.7 ± 19.6 months), resulting in a post-EDAS/EMAS stroke rate of 1 stroke per 39.3 patient-years, a 5-fold reduction compared with that in the pre-EDAS/EMAS period. The patients' mean pre-EDAS/EMAS HbS level of 29.5% ± 6.4% was comparable to the mean post-EDAS/EMAS HbS level of 25.5% ± 6.1% (p = 0.104). CONCLUSIONS The results of this retrospective case series in a large cohort of pediatric patients with SCD and MMS suggest that EDAS/EMAS provides a stroke-prevention benefit with an acceptably low morbidity rate. Given the combined experience with EDAS and EMAS for this indication at this and other institutions, a prospective clinical trial to assess their efficacy compared with that of chronic transfusion therapy alone is warranted.

Background: With the increasing use of endovascular techniques in the treatment of both ruptured and unruptured intracranial aneurysms, the issue of obliteration efficacy has become increasingly important., Objective: To systematically develop a comprehensive model for predicting retreatment with various types of endovascular treatment., Methods: We retrospectively reviewed medical records that were prospectively collected for 305 patients who received endovascular treatment for intracranial aneurysms from 2007 to 2013. Multivariable logistic regression was performed on candidate predictors identified by univariable screening analysis to detect independent predictors of retreatment. A composite risk score was constructed based on the proportional contribution of independent predictors in the multivariable model., Results: Size (>10 mm), aneurysm rupture, stent assistance, and posttreatment degree of aneurysm occlusion were independently associated with retreatment, whereas intraluminal thrombosis and flow diversion demonstrated a trend toward retreatment. The Aneurysm Recanalization Stratification Scale was constructed by assigning the following weights to statistically and clinically significant predictors: aneurysm-specific factors: size (>10 mm), 2 points; rupture, 2 points; presence of thrombus, 2 points. Treatment-related factors were stent assistance, -1 point; flow diversion, -2 points; Raymond Roy occlusion class 2, 1 point; Raymond Roy occlusion class 3, 2 points. This scale demonstrated good discrimination with a C-statistic of 0.799., Conclusion: Surgical decision making and patient-centered informed consent require comprehensive and accessible information on treatment efficacy. We constructed the Aneurysm Recanalization Stratification Scale to enhance this decision-making process. This is the first comprehensive model that has been developed to quantitatively predict the risk of retreatment after endovascular therapy.

Variations of the anterior cerebral artery-anterior communicating artery complex are commonly identified in aneurysm surgery. An infraoptic course of the anterior cerebral artery is exceedingly rare. Robison first described this anomaly from an anatomic dissection in 1959. A unilateral anomalous infraoptic anterior cerebral artery is more common than anomalies of bilateral infraoptic anterior cerebral arteries. We present the case of an unruptured aneurysm at the anterior communicating artery in a patient with bilateral infraoptic anterior cerebral arteries, identified by computed tomography angiography and verified during surgery. Implications for aneurysm formation and surgical treatment are discussed.

Endospore formation by Bacillus subtilis is a complex and dynamic process. One of the major challenges of sporulation is the assembly of a protective, multilayered, proteinaceous spore coat, composed of at least 70 different proteins. Spore coat formation can be divided into two distinct stages. The first is the recruitment of proteins to the spore surface, dependent on the morphogenetic protein SpoIVA. The second step, known as encasement, involves the migration of the coat proteins around the circumference of the spore in successive waves, a process dependent on the morphogenetic protein SpoVID and the transcriptional regulation of individual coat genes. We provide genetic and biochemical evidence supporting the hypothesis that SpoVID promotes encasement of the spore by establishing direct protein-protein interactions with other coat morphogenetic proteins. It was previously demonstrated that SpoVID directly interacts with SpoIVA and the inner coat morphogenetic protein, SafA. Here, we show by yeast two-hybrid and pulldown assays that SpoVID also interacts directly with the outer coat morphogenetic protein, CotE. Furthermore, by mutational analysis, we identified a specific residue in the N-terminal domain of SpoVID that is essential for the interaction with CotE but dispensable for the interaction with SafA. We propose an updated model of coat assembly and spore encasement that incorporates several physical interactions between the principal coat morphogenetic proteins.

Endospores formed by Bacillus subtilis are encased in a tough protein shell known as the coat, which consists of at least 70 different proteins. We investigated the process of spore coat morphogenesis using a library of 40 coat proteins fused to green fluorescent protein and demonstrate that two successive steps can be distinguished in coat assembly. The first step, initial localization of proteins to the spore surface, is dependent on the coat morphogenetic proteins SpoIVA and SpoVM. The second step, spore encasement, requires a third protein, SpoVID. We show that in spoVID mutant cells, most coat proteins assembled into a cap at one side of the developing spore but failed to migrate around and encase it. We also found that SpoIVA directly interacts with SpoVID. A domain analysis revealed that the N-terminus of SpoVID is required for encasement and is a structural homologue of a virion protein, whereas the C-terminus is necessary for the interaction with SpoIVA. Thus, SpoVM, SpoIVA and SpoVID are recruited to the spore surface in a concerted manner and form a tripartite machine that drives coat formation and spore encasement.