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Polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocycles are thought to be widespread throughout the universe, because these classes of molecules are probably responsible for the unidentified infrared bands, a set of emission features seen in numerous Galactic and extragalactic sources. Despite their expected ubiquity, astronomical identification of specific aromatic molecules has proven elusive. We present the discovery of benzonitrile ( c -C 6 H 5 CN), one of the simplest nitrogen-bearing aromatic molecules, in the interstellar medium. We observed hyperfine-resolved transitions of benzonitrile in emission from the molecular cloud TMC-1. Simple aromatic molecules such as benzonitrile may be precursors for polycyclic aromatic hydrocarbon formation, providing a chemical link to the carriers of the unidentified infrared bands., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Purpose: To investigate knee kinematics in response to physical examinations to determine the effect of anterolateral capsular injury and lateral extra-articular tenodesis (LET) in anterior cruciate ligament (ACL)-deficient and -reconstructed knees., Methods: Seven human lower limb cadavers were used in this study (mean age, 60 years; age range, 56-63 years). Physical examinations were performed, including the pivot-shift test, Lachman test, anterior drawer at 90°, and internal and external tibial rotation at 30°, 60°, and 90° of knee flexion. ACL injury and reconstruction and LET, all with and without an injured anterolateral capsule, were investigated. Tibial translation and rotation relative to the femur were measured by an electromagnetic tracking system during the physical examination., Results: Anterior translation of the lateral knee compartment and internal tibial rotation during the pivot-shift test were highest in combined ACL-deficient and anterolateral capsule-deficient knees (12.3 ± 7.4 mm and 16.3° ± 8.5°, respectively). With the presence of an anterolateral capsular injury, a combined ACL reconstruction and LET reduced the anterior translation of the lateral knee compartment during the pivot-shift test significantly (P = .042), whereas anatomic ACL reconstruction did not. Internal tibial rotation displayed overconstraint when a LET was performed, especially when the anterolateral capsule was intact., Conclusions: ACL reconstruction in combination with a LET was able to reduce anterior tibial translation and internal tibial rotation in response to different physical examinations. However, combined ACL reconstruction and LET led to overconstraint of internal tibial rotation when the anterolateral capsule was intact. CLINICAL RELEVANCE: On the basis of our results, LET with ACL reconstruction restores stability in a combined ACL-injured and anterolateral capsule-injured knee. However, LET with ACL reconstruction overconstrains the knee in an isolated ACL injury., (Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Introduction: The purpose of this study is to examine the feasibility and acceptability of incorporating a mobile application, Stay Quit Coach, into an integrated care smoking-cessation treatment protocol for veterans with posttraumatic stress disorder (PTSD)., Methods: Participants included veteran smokers aged 18-69 years with PTSD. The integrated care protocol includes eight weekly PTSD-informed cognitive behavioral therapy sessions for smoking cessation, followed by monthly booster sessions and a prescription for standard smoking-cessation medications if desired. Participants used Stay Quit Coach as desired. Outcome measures at 3-month follow-up included: adherence (sessions attended), 30-day point-prevalence abstinence bioverified with carbon monoxide <6 parts per million, past-30 day mean daily cigarette use, exhaled carbon monoxide, nicotine dependence, and PTSD symptom severity. Repeated outcomes were analyzed with random-intercept linear mixed models. Data were collected in 2015-2016 and analyses were conducted in 2016-2017., Results: Participants (n=20) were 95% male and 5% female; mean age 41.4 (SD=16.2) years. Thirteen participants (65%) attended all scheduled sessions, four (20%) did not adhere to the protocol on schedule, and three (15%) were lost to follow-up. At 3-month follow-up, six of 17 completers (35.3%) had bioverified 30-day point-prevalence abstinence. Nicotine dependence, carbon monoxide levels, and past 30-day cigarette use significantly decreased and PTSD symptoms were unchanged from baseline to follow-up. Participants self-reported using Stay Quit Coach 2.5 (SD=2.2) days/week; 15 of 17 (88.2%) reported using Stay Quit Coach <30 minutes/week; two of 17 (11.8%) reported using Stay Quit Coach 30-60 minutes/week., Conclusions: Although results must be interpreted with caution given the lack of control group and small sample size, findings indicate that integrating Stay Quit Coach into integrated care was feasible and acceptable., (Published by Elsevier Inc.)

Variability in anatomic terminology, dissection protocols, and use of embalmed as opposed to fresh frozen specimens has led to the controversy surrounding the "anterolateral ligament of the knee." Conceptually the complex anatomy of the anterolateral knee is made up of the superficial, middle, deep, and capsulo-osseous layers of the iliotibial band. The anterolateral capsule is deep to these tissues and is directly attached to the lateral meniscus. These structures collectively form the anterolateral complex of the knee. The anterolateral complex in conjunction with the anterior cruciate ligament function to prevent anterolateral rotatory instability of the knee., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The role of the anterolateral complex of the knee in providing static and rotatory knee stability has been a source of renewed interest in the literature. Several studies have established a role of the anterolateral complex in controlling knee rotational stability. Although the objective quantification of knee kinematics and stability has been investigated, understanding of the structural properties of the anterolateral complex is evolving. This article highlights recent evidence pertaining to the structural properties of the anterolateral structures. The biomechanical evaluation of the structural properties of the anterolateral complex of the knee yielded minimal involvement in controlling knee rotational stability., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Introduction: Knee injuries and especially anterior cruciate ligament (ACL) tears are frequent in athletes. Therefore, primary and secondary prevention of sports-related lower limb injuries is an ongoing topic of interest. The aim of present study was to establish guidelines for the prevention of knee and ACL injuries on the basis of evidence-based concepts represented in current literature., Methods: A comprehensive literature review regarding prevention programs for knee and ACL injuries was conducted., Results: Several modifiable and non-modifiable risk factors for knee injuries in athletes have been reported in literature. Referring to the ACL, specific injury mechanisms have been identified and are well understood. In particular, it has been demonstrated that dynamic valgus is one of the most important modifiable risk factors. Simple tests like the drop jump test have shown their efficacy in screening and detecting athletes at risk. There is only few evidence for the preventive effect on knee and ACL injuries by single exercises. However, in order to prevent or correct endangering movement patterns including dynamic valgus, several complex prevention programs have been developed in the past. These prevention programs are included in standard warm-up exercises and are focusing on muscle strength, balance, and proprioception, as well as running and flexibility. It is reported that these training programs can reduce the incidence of knee injuries by up to 27% and ACL injuries by up to 51%., Conclusions: Screening, identification, and correction of endangering movement patterns like the dynamic valgus are the first crucial steps in order to prevent knee and ACL injuries in athletes. Furthermore, jumping, running and flexibility exercises as well as balance and strength training are proven to reduce the incidence of these injuries and should, therefore, be integrated into the regular warm up program. Appropriate complete prevention programs are freely accessible via the Internet and should be adapted to the specific sport disciplines.

Purpose: Posterior horn meniscal tears are commonly found in conjunction with anterior cruciate ligament (ACL) injury. Some believe tears in the posterior meniscocapsular zone, coined ramp lesions, are important to knee stability. The purpose of this study was to determine whether pre-operative MRI evaluation was able to accurately and reproducibly identify ramp lesions., Methods: Three blinded reviewers assessed MRIs twice for the presence of ramp lesions in patients undergoing ACL reconstruction. Sensitivity, specificity, negative predictive value, and positive predictive value for MRI were calculated based on arthroscopic diagnosis of a ramp lesion. Intra-class correlation coefficient was calculated to assess intra- and interobserver reliability of the MRI assessment between the three examiners. Significance was set at p < 0.05., Results: Ninety patients met inclusion criteria (45 males, 45 females, mean age 28.0 years). Thirteen of these patients had arthroscopy-confirmed ramp lesions, while the other 77 had other meniscal pathology. Sensitivity of detecting a ramp lesion on MRI ranged from 53.9 to 84.6%, while specificity was 92.3-98.7%. Negative predictive value was 91.1-97.4%, while positive predictive value was 50.0-90.0%. Inter-rater reliability between three reviewers was moderate at 0.56. The observers had excellent intra-rater reliability ranging from 0.75 to 0.81., Conclusions: This study demonstrates high sensitivity and excellent specificity in detecting meniscal ramp lesions on MRI. Ramp lesions are likely more common and may have greater clinical implications than previously appreciated; the outcomes of untreated lesions must be investigated. Pre-operative identification of ramp lesions may aid clinicians in surgical planning and patient education to improve outcomes by addressing pathology which may have otherwise been missed., Level of Evidence: III.

Background: Isokinetic strength testing is an important tool in the evaluation of the physical capacities of athletes as well as for decision making regarding return to sports after anterior cruciate ligament (ACL) reconstruction in both athletes and the lay population. However, isokinetic testing is time consuming and requires special testing equipment., Hypothesis: A single-jump test, regardless of leg dominance, may provide information regarding knee extension strength through the use of correlation analysis of jump height and peak torque of isokinetic muscle strength., Study Design: Cross-sectional study; Level of evidence, 3., Methods: A total of 169 patients who underwent ACL reconstruction were included in this study. Isokinetic testing was performed on the injured and noninjured legs. Additionally, a single-leg countermovement jump was performed to assess jump height using a jump accelerometer sensor. Extension strength values were used to assess the association between isokinetic muscle strength and jump height., Results: The sample consisted of 60 female (mean age, 20.8 ± 8.3 years; mean weight, 61.7 ± 6.5 kg; mean height, 167.7 ± 5.3 cm) and 109 male (mean age, 23.2 ± 7.7 years; mean weight, 74.6 ± 10.2 kg; mean height, 179.9 ± 6.9 cm) patients. Bivariate correlation analysis showed an association ( r = 0.56, P < .001) between jump height and isokinetic extension strength on the noninvolved side as well as an association ( r = 0.52, P < .001) for the involved side. Regression analysis showed that in addition to jump height (beta = 0.49, P < .001), sex (beta = -0.17, P = .008) and body mass index (beta = 0.37, P < .001) affected isokinetic strength. The final model explained 51.1% of the variance in isokinetic muscle strength, with jump height having the strongest impact (beta = 0.49, P < .001) and explaining 31.5% of the variance., Conclusion: Initial analysis showed a strong association between isokinetic strength and jump height. The study population encompassed various backgrounds, skill levels, and activity profiles, which might have affected the outcome. Even after controlling for age and sex, isokinetic strength was still moderately associated with jump height. Therefore, the jump technique and type of sport should be considered in future research., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: Institutional support for this research was provided by CoRehab.

Background: Significant controversy exists regarding the anterolateral structures of the knee., Purpose: To determine the layer-by-layer anatomic structure of the anterolateral complex of the knee., Study Design: Descriptive laboratory study., Methods: Twenty fresh-frozen cadaveric knees (age range, 38-56 years) underwent a layer-by-layer dissection to systematically expose and identify the various structures of the anterolateral complex. Quantitative measurements were performed, and each layer was documented with high-resolution digital imaging., Results: The anterolateral complex of the knee consisted of different distinct layers, with the superficial and deep iliotibial band (ITB) representing layer 1. The superficial ITB had a distinct connection to the distal femoral metaphysis and femoral condyle (Kaplan fibers), and the deep layers of the ITB were identified originating at the level of the Kaplan fibers proximally. This functional unit, consisting of the superficial and deep ITB, was reinforced by the capsulo-osseous layer of the ITB, which was continuous with the fascia of the lateral gastrocnemius and biceps femoris muscles. These 3 components of the ITB became confluent distally, and the insertion spanned from the Gerdy tubercle anteriorly to the lateral tibia posteriorly on a small tubercle (lateral tibial tuberosity). Layer 3 consisted of the anterolateral capsule, in which 35% (7/20) of specimens had a discreet mid-third capsular ligament., Conclusion: The anterolateral complex consists of the superficial and deep ITB, the capsulo-osseous layer of the ITB, and the anterolateral capsule. The anterolateral complex is defined by the part of the ITB between the Kaplan fibers proximally and its tibial insertion, which forms a functional unit. A discrete anterolateral ligament was not observed; however, the anterolateral ligament described in recent studies likely refers to the capsulo-osseous layer or the mid-third capsular ligament., Clinical Relevance: The anterolateral knee structures form a complex functional unit. Surgeons should use caution when attempting to restore this intricate structure with extra-articular procedures designed to re-create a single discreet ligament., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: Support for this research was received from the Department of Orthopaedic Surgery of the University of Pittsburgh.

Background: Trochlear dysplasia is an important risk factor associated with patellofemoral instability, but it remains difficult to classify with consistency. Currently there is no objective way to quantify the dysplasia. The purpose of this study is to define and quantify objectively the trochlear morphology by volume and length via computed tomography (CT)., Methods: One-hundred control patients (136 knees) were retrospectively reviewed and compared to 36 consecutive patients (72 knees) who were treated surgically for recurrent patellar instability and known trochlear dysplasia based on a lateral radiograph. Trochlear morphology was analyzed from a pre-operative CT and data presented as trochlear sulcus volume trochlear length. To determine where along the trochlear length dysplasia is most variable, the trochlear length was radiographically divided into thirds, volume was quantified along that section and compared to control trochlear., Results: A significant difference in trochlear morphology exists between cohorts, volume (1.98 vs 3.77cm 3 ) and length (31.97 vs 34.66mm) (p<0.05). However, there appears to be a gender based difference in trochlea morphology. The trochlea volumetric analysis between the female cohorts (L: 2.02cm 3 vs. 2.94cm 3 , R: 1.95cm 3 vs. 2.93cm 3 ) demonstrated significantly less volume in instability patients (p<0.001). The proximal third of the trochlear contributed the majority of dysplasia difference determined by comparing mean trochlear volume, 95% of the difference. This difference decreased in distal sections, 53% and 32% respectively., Conclusion: This reproducible technique can be used to quantify the trochlea morphology, in order to describe the severity of a dysplasia., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Exercise has beneficial effects for physical health outcomes and has also been shown to reduce the severity of psychological health symptoms. Recent studies have shown a potentially positive impact of exercise on posttraumatic stress disorder (PTSD). Prominent among those with PTSD, sleep disturbance and nightmares are among the top three PTSD symptoms commonly reported by treatment-seeking Veterans. Regular physical exercise has been consistently associated with better sleep. This study utilized a longitudinal design to explore the relationship between exercise and sleep among Veterans with PTSD symptoms at baseline and one-year follow-up., Materials and Methods: Veterans (n = 76) who served in support of Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn were recruited for this study. Correlations were assessed between PTSD symptoms, sleep, and engagement in exercise at each time point (baseline, one-year follow-up). Regression analyses were conducted to examine the relationship between engagement in exercise at baseline and PTSD symptoms at one-year follow-up, as well as sleep quality at one-year follow-up. Regression models controlled for demographic variables (age and gender), alcohol use, baseline PTSD symptoms, and baseline sleep quality., Results: Multiple regression analyses demonstrated that engagement in exercise at baseline was significantly associated with better sleep quality at one-year follow-up while controlling for age, gender, alcohol use, baseline PTSD symptoms, and baseline sleep quality (β = -0.128, p < 0.05). Multiple regression analyses examining the relationship between engagement in exercise at baseline and PTSD symptoms at one-year follow-up (controlling for age, gender, alcohol use, baseline PTSD symptoms, and baseline sleep quality) did not yield statistically significant results (β = 0.053, p = 0.57)., Conclusion: Results from the present study found that engagement in exercise at baseline was associated with better sleep quality at one-year follow-up. These findings were consistent with the current literature suggesting exercise can have a positive impact on sleep quality. Furthermore, our findings suggest that exercise could be considered as an adjunctive intervention for individuals with PTSD-particularly for those patients whose difficulties with sleep are predominant. Given that exercise is highly accessible and is embedded in the military culture, future research should examine the way in which exercise can be leveraged in PTSD treatment, specifically in ameliorating sleep difficulties. Exercise may also reap demonstrable public health benefits in multiple psychological and physical domains and reduce the psychiatric and medical morbidity and mortality associated with PTSD., (Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.)

Background: The Segond fracture was classically described as an avulsion fracture of the anterolateral capsule of the knee. Recently, some authors have attributed its pathogenesis to the "anterolateral ligament" (ALL). Biomechanical studies that have attempted to reproduce this fracture in vitro have reported conflicting findings., Purpose: To determine the anatomic characteristics of the Segond fracture on plain radiographs and magnetic resonance imaging (MRI), to compare this location with the location of the ALL described in prior radiographic and anatomic publications, and to determine the fracture's attachments to the soft tissue anterolateral structures of the knee., Study Design: Case series; Level of evidence, 4., Methods: A total of 36 anterior cruciate ligament-injured patients with Segond fractures (33 male, 3 female; mean age, 23.2 ± 8.4 years) were enrolled. MRI scans were reviewed to determine the anatomic characteristics of the Segond fracture, including the following: proximal-distal (PD) length, anterior-posterior (AP) width, medial-lateral (ML) width, PD distance to the lateral tibial plateau, AP distance to the Gerdy tubercle (GT), and AP distance from the GT to the posterior aspect of the fibular head. The attachment of the anterolateral structures to the Segond fragment was then categorized as the iliotibial band (ITB) or anterolateral capsule. Interrater reliability of the measurements was determined by calculating the Spearman rank correlation coefficient. MEDLINE, Web of Science, and the Cochrane Library were searched from inception to May 2016 for the following keywords: (1) "Segond fracture," (2) "anterolateral ligament," (3) "knee avulsion," (4) "lateral tibia avulsion," and (5) "tibial plateau avulsion." All studies describing the anatomic location of the Segond fracture and the ALL were included in the systematic review., Results: On plain radiographs, the mean distance of the midpoint of the fracture to the lateral tibial plateau was 4.6 ± 2.2 mm. The avulsed fracture had a mean PD length of 9.2 ± 2.5 mm and a mean ML width of 2.4 ± 1.4 mm. On MRI, the mean distance of the proximal fracture to the tibial plateau was 3.4 ± 1.6 mm. The mean PD length was 8.7 ± 2.2 mm, while the mean AP width was 11.1 ± 2.2 mm. The mean distance between the GT and the center of the fracture was 26.9 ± 3.3 mm, while the mean distance between the GT and the posterior fibular head was 53.9 ± 4.4 mm. The mean distance of the midpoint of the fracture to the tibial plateau was 7.8 ± 2.7 mm, while the center of the fracture was 49.9% of the distance between the GT and the posterior aspect of the fibular head. Analysis of soft tissue structures attached to the fragment revealed that the ITB attached in 34 of 36 patients and the capsule attached in 34 of 36 patients. One patient had only the capsule attached, another had only the ITB attached, and the last showed neither clearly attached. A literature review of 20 included studies revealed no difference between the previously described Segond fracture location and the tibial insertion of the ALL., Conclusion: The results of this study confirmed that while the Segond fracture occurs at the location of the tibial insertion of the ALL, as reported in the literature, MRI was unable to identify any distinct ligamentous attachment. MRI analysis revealed that soft tissue attachments to the Segond fracture were the posterior fibers of the ITB and the lateral capsule in 94% of patients.

The collisions between high-energy ions and solids can result in significant physical and chemical changes to the material. These effects are potentially important for better understanding the chemistry of interstellar and planetary bodies, which are exposed to cosmic radiation and the solar wind, respectively; however, modeling such collisions on a detailed microscopic basis has thus far been largely unsuccessful. To that end, a new model, entitled CIRIS: the Chemistry of Ionizing Radiation in Solids, was created to calculate the physical and chemical effects of the irradiation of solid materials. With the new code, we simulate O 2 ice irradiated with 100 keV protons. Our models are able to reproduce the measured ozone abundances of a previous experimental study, as well as independently predict the approximate thickness of the ice used in that work.

Purpose: The purpose of this study is to compare the clinical outcome of ACL reconstructions in patients older than 40 years of age to younger subjects. It has been hypothesized that patients older than 40 years of age achieve comparable clinical outcomes following acute ACL reconstruction using a hamstring tendon autograft than younger patients., Methods: Patients with an isolated ACL tear without any concomitant injuries and subsequent ACL reconstruction within 48 h from injury were included in this prospective study. According to patients' age, subjects were assigned to two groups: (A) 18-40 years and (B) 40-60 years. Functional outcomes, pain, post-operative radiographs and return to sports were recorded and analysed. The follow-up period was 24 months., Results: A total of 59 patients were included in the study. Group A consisted of 39 patients (14 women, 25 men; median 27 years), group B of 20 patients (12 women, 8 men; median 45 years) respectively. At final follow-up, the Lysholm score showed no significant difference between group A (median 90; range 68-100) and group B (median 94.5; range 63-100) (n.s.). The final Tegner score showed a significant difference between group A (median 6; range 2-9) and group B (median 5.5; range 3-8) (p < 0.05). The mean VAS pain score was 1.3 (range 0-6) in group A and 1 (range 0-7) in group B, respectively (n.s.). Both groups returned to their pre-injury activity level and did not significantly change their activity in respect of pivoting sports and sports frequency at final follow-up (n.s.). According to the IKDC score, all except one of the patients in group A and all patients in group B had a normal or nearly normal final outcome (n.s.)., Conclusion: Patients older than 40 years of age achieve comparable clinical outcomes following acute ACL reconstruction using a hamstring tendon autograft than younger patients., Level of Evidence: Cohort study, Level III.

Purpose: The presence of anterolateral ligament of the knee is still controversial, and some physicians prefer to call this structure anterolateral complex (ALC) to infer plural nature of structures involved. The purpose of this study was to describe the scanning techniques and to classify various sonographic appearances of the tibial-side ALC of the knee in subjects with anterior cruciate ligament (ACL) injury. It was hypothesized that sonographic abnormity of the ALC would be associated with ACL injury history., Methods: Patients with a history of unilateral ACL injury were prospectively recruited, and the ALC was sonographically evaluated. During the evaluation, the lateral femoral epicondyle was visualized in anatomic transverse view first. At this location, the ALC was typically most conspicuous between the short head of the biceps femoris muscle and the posterior and deep aspect of the iliotibial band superficial to the origin of the lateral collateral ligament. The ALC was followed distally to the broad insertion centralizing to the area posterior to Gerdy's tubercle. The appearance of the distal insertion of the ALC was classified based both on echogenicity and on the presence of a Segond fracture as follows: Grade 0: isoechoic to the rest of the ALC, Grade 1: hypoechoic, Grade 2: anechoic, and Grade 3: Segond fracture. The uninjured side was similarly scanned for comparison., Results: A total of 28 patients (13 men; mean age 22.1 ± 8.1 years old with range: 12-44; mean body mass index 25.0 with range: 18.9-39.2) were included in this study. The average time from injury to sonograhpic evaluation was 4 months (range: 2 days to 1 year). Of 28 ACL-deficient knees, 19 were (68%) graded as Grade 0 in the distal insertion of the ALC, 7 (25%) as Grade 1, 1 (3.5%) as Grade 2, and 1 (3.5%) as Grade 3. Contralateral knees showed 25 knees (89%) with Grade 0 and 3 knees (11%) with Grade 1., Conclusion: ACL injury history was associated with a higher incidence of sonographic abnormalities within the distal insertion of the anterolateral complex., Level of Evidence: III.

Injuries to the anterolateral complex of the knee can result in increased rotatory knee instability. However, to diagnose and treat patients with persistent instability properly, surgeons need to understand the multifactorial genesis as well as the complex anatomy of the anterolateral aspect of the knee in its entirety. While recent research focused primarily on one structure (anterolateral ligament-ALL), the purpose of this pictorial essay is to provide a detailed layer-by-layer description of the anterolateral complex of the knee, consisting of the iliotibial band with its superficial, middle, deep, and capsulo-osseous layer as well as the anterolateral joint capsule. This may help surgeons to not only understand the anatomy of this particular part of the knee, but may also provide guidance when performing extra-articular procedures in patients with rotatory knee instability. Level of evidence V.

As the incidence of anterior cruciate ligament (ACL) reconstruction continues to increase, the rate of revision surgery continues to climb. Revision surgery has inherent challenges that must be addressed in order to achieve successful results. The cause of the primary ACL reconstruction failure should be determined, and careful preoperative planning should be performed to address the cause(s) of failure. Each patient undergoing revision surgery should undergo a thorough history and physical examination, receive full length alignment radiographs, lateral radiographs, 45-degree flexion weight-bearing postero-anterior radiographs, and patellofemoral radiographs. 3-dimensional computed topography (CT) scan should be performed to assess tunnel position and widening. Magnetic resonance imaging (MRI) should be used to assess for intra-articular soft tissue pathology. Meniscal tears, meniscal deficiency, anterolateral capsule injuries, bony morphology, age, activity level, connective tissue diseases, infection, graft choice, and tunnel position can all impact the success of ACL reconstruction surgery. Meniscal lesions should be repaired, and in cases of persistent rotatory instability, extra-articular procedures may be indicated. Furthermore, osteotomies may be needed to correct malalignment or excess posterior tibial slope. Depending on the placement and condition of the original femoral and tibial tunnels, revision surgery may be performed in a single procedure or in a staged manner. In most cases, the surgery can be performed in one procedure. Regardless, the surgeon must communicate with the patient openly regarding the implications of revision ACL surgery and the treatment plan should be developed in a shared fashion between the surgeon and the patient.

Purpose: The purpose of the present study is the comparison of acute ACL reconstruction with or without meniscus repair within 48 h after injury and a delayed surgery during the inflammation-free interval. It was hypothesized that acute ACL reconstruction results in inferior patient reported outcomes and higher frequency of range of motion deficits., Methods: The effect of acute (within 48 h) and delayed (during the inflammation-free interval) ACL surgery was prospectively studied on 160 consecutive patients with ACL injury between January 2010 and December 2011. Subgroup analyses were performed to evaluate patients with an additional meniscus repair separately from isolated ACL surgeries. During the study period, partial meniscectomies were recorded to evaluate time dependent meniscus reparability. Patient reported outcomes, objective IKDC and manual stability measurements were documented during the 24-month follow-up period. The Pearson Chi-squared test was used to evaluate objective outcome measures. The Mann-Whitney U test was performed to analyse the results of patient reported outcomes. Statistical significance was set at p < 0.05., Results: For patients who underwent isolated ACL reconstruction, no statistical significant difference was observed at any time point regarding objective and subjective outcome measures. Significantly fewer patients who underwent acute combined ACL reconstruction and meniscus repair had an extension deficit between 3° and 5° at 12 months following surgery (3.7 vs. 22.2 %, p < 0.05). No difference regarding cyclops removal, re-injury of ACL or meniscus was found between the two surgical timing groups. Further, surgical timing did not influence the reparability of the meniscus., Conclusion: An acute ACL reconstruction within 48 h is preferable in highly active patients or competitive athletes., Level of Evidence: Prospective cohort study, Level II.

Purpose: The purpose of the present study was to biomechanically compare three different posterior meniscal root repair techniques. Transtibial fixation of a posterior meniscus root tear (PMRT) combined with an anterior cruciate ligament (ACL) reconstruction via one tunnel only shows similar properties in terms of cyclic loading and load to failure compared with direct anchor fixation., Methods: Twenty-eight porcine knees were randomly assigned to 4 groups (n = 7 each): (1) native posterior meniscal root, (2) suture anchor repair, (3) refixation via a tibial ACL tunnel in combination with an interference screw fixation of the ACL graft, and (4) refixation via a tibial ACL tunnel in combination with an interference screw fixation of the ACL graft with an additional extracortical button fixation. The four groups underwent cyclic loading followed by a load-to-failure testing. Construct elongation during 1000 cycles, dynamic stiffness, attenuation, maximum force during load-to-failure testing, and failure mode were recorded., Results: All reconstructions showed a significant lower maximum load (p < 0.0001) compared with the native meniscal root. The elongation for the transtibial fixation via the ACL tunnel without an additional extracortical backup fixation was significantly higher compared with the suture anchor technique (p < 0.0001). The additional use of a backup fixation led to similar results compared with the anchor repair technique., Conclusion: The transtibial refixation of the meniscal root can be combined with an ACL reconstruction using the same tibial bone tunnel. However, an additional extracortical backup fixation is necessary. This might avoid a slippage of suture material and a failure of meniscus root fixation.

Purpose: Publications describing tendon graft reconstruction for anterior sternoclavicular joint (SCJ) instability are rare and usually refer to small patient numbers. The aim of this study was to systematically review the literature regarding outcomes and complications following tendon graft reconstruction techniques for anterior SCJ instability., Methods: An online database was systematically searched to identify studies on graft reconstruction for anterior SCJ instability. Reported outcome scores were graded as excellent, good, fair and poor to summarize the study results. All reported complications were recorded., Results: Five articles with a total of 80 patients met the inclusion criteria. Reported outcomes were excellent in 10 %, good in 89 % and fair in 1 %. Recurrent instability was found in 10 % of the patients, and 5 % underwent revision surgery due to persistent impairment of shoulder function related to SCJ instability or osteoarthritis., Conclusion: Surgical stabilization techniques for the SCJ using autologous tendon grafts have shown to be safe and reliable and make better patients' pain situation and shoulder function. However, a certain amount of impairment might persist, which needs to be discussed with patients. Severe complications were rare and revision rates were as low as 5 %. Therefore, graft reconstruction techniques should be considered for patients with chronic anterior SCJ instability after a course of failed conservative treatment. This study is valuable for clinicians in daily clinical practice when dealing with this difficult-to-treat pathology and can help surgeons to better predict the clinical outcomes and complications following SCJ graft reconstruction. It should, however, not lead to underestimation of the potential risks of the procedure., Level of Evidence: Systematic review, Level IV.

Purpose: To compare clinical and radiologic results of primary anterior cruciate ligament (ACL) suture anchor repair and microfracturing with anatomic ACL single-bundle reconstruction in patients with acute proximal ACL avulsion tears., Methods: Between January 2010 and December 2013, 420 patients underwent ACL treatment. Forty-one patients were included in this study. The inclusion criteria were as follows: unilateral acute proximal ACL rupture, concomitant meniscus lesions, no previous knee ligament surgery, and no additional ligament injuries or absence of ligament injury of the contralateral knee. Preoperative magnetic resonance imaging confirming a proximal avulsion tear of the ACL was required. Patients had to undergo surgical treatment within 6 weeks after injury. Follow-up examination included Lachman and pivot-shift testing, KT-1000 measurement, and the International Knee Documentation Committee score., Results: At a mean follow-up of 28 months (range, 24 to 31 month), 20 patients in each group were available. A mean KT-1000 arthrometer result of less than 3 mm indicated stability in all patients (P = .269). Three patients had a 1+ Lachman test (P = .072) and 4 patients had a 1+ pivot-shift test in the ACL repair group (P = .342). The International Knee Documentation Committee score results did not differ significantly (P > .99), but there was a significant correlation between poor results and failure rate (P = .001) in the refixation group. The failure rate was 15% in the ACL refixation group and 0% in the reconstruction group (P = .231). Magnetic resonance imaging confirmed homogeneous signal and proper ACL position in 100% of patients in the control group and 86% in the ACL repair group., Conclusions: Proximal refixation of the ACL using knotless suture anchors and microfracturing restores knee stability and results in comparable functional outcomes to a control group treated with single-bundle ACL reconstruction. The results suggest that refixation of the ACL is a feasible treatment option in selected patients., Level of Evidence: Level III, case-control study., (Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the biomechanical stability of a tendon-to-clavicle bone interface fixation of a graft in revision acromioclavicular reconstruction., Methods: Fifteen fresh-frozen cadaveric shoulders were used. All specimens underwent bone density evaluation. For the primary reconstruction, a 5-mm semitendinosus allograft was inserted into a 5-mm bone tunnel at 25 and 45 mm from the lateral end of the clavicle using a 5.5 × 8-mm PEEK (polyether ether ketone) tenodesis screw. Each single graft was fixed in a cryo-clamp and cyclically loaded from 5 to 70 N for 3,000 cycles, followed by load-to-failure testing at a rate of 120 mm/min to simulate the revision case. To simulate tunnel widening, the tunnels of the revision series were over-drilled with an 8-mm drill, and a 5-mm semitendinosus graft with an 8 × 12-mm PEEK tenodesis screw was inserted. Biomechanical testing was then repeated., Results: The bone mineral density analysis showed a significantly higher density at the 45-mm hole compared with the 25-mm hole (P = .001). The ultimate load to failure increased from the 5.5-mm screw to the 8-mm screw at the 45-mm hole position (P = .001). There was no statistically significant difference at the 25-mm hole position (P = .934). No statistical significance for graft elongation comparing the 5.5-mm screw and the 8-mm screw at the 25-mm (P = .156) and 45-mm (P = .334) positions could be found., Conclusions: Comparable biomechanical stability for the tendon-to-bone interface fixation in different clavicular tunnel diameters simulating primary and revision reconstruction was achieved., Clinical Relevance: There is a lack of literature regarding revision acromioclavicular joint reconstruction, but our biomechanical results show comparable stability to primary reconstruction. These data provide support for the use of anatomic acromioclavicular ligament reconstruction in revision cases., (Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

The stem cell as the building block necessary for tissue reparation and homeostasis plays a major role in regenerative medicine. Their unique property of being pluripotent, able to control immune process and even secrete a whole army of anabolic mediators, draws interest. While new arthroscopic procedures and techniques involving stem cells have been established over the last decade with improved outcomes, failures and dissatisfaction still occur. Therefore, there is increasing interest in ways to improve the healing response. MSCs are particularly promising for this task given their regenerative potential. While methods of isolating those cells are no longer poses a challenge, the best way of application is not clear. Several experiments in the realm of basic science and animal models have recently been published, addressing this issue, yet the application in clinical practice has lagged. This review provides an overview addressing the current standing of MSCs in the field of arthroscopic surgery.

Complex organic molecules such as sugars and amides are ubiquitous in star- and planet-forming regions, but their formation mechanisms have remained largely elusive until now. Here we show in a combined experimental, computational, and astrochemical modeling study that interstellar aldehydes and enols like acetaldehyde (CH3CHO) and vinyl alcohol (C2H3OH) act as key tracers of a cosmic-ray-driven nonequilibrium chemistry leading to complex organics even deep within low-temperature interstellar ices at 10 K. Our findings challenge conventional wisdom and define a hitherto poorly characterized reaction class forming complex organic molecules inside interstellar ices before their sublimation in star-forming regions such as SgrB2(N). These processes are of vital importance in initiating a chain of chemical reactions leading eventually to the molecular precursors of biorelevant molecules as planets form in their interstellar nurseries.

Purpose: To biomechanically compare the stability of the coracoid process after an anatomic double-tunnel technique using two 4-mm drill holes or a single-tunnel technique using one 4-mm or one 2.4-mm drill hole., Methods: For biomechanical testing, 18 fresh-frozen cadaveric scapulae were used and randomly assigned to one of the following groups: two 4-mm drill holes (group 1), one 4-mm drill hole (group 2), or one 2.4-mm drill hole (group 3). After standardized coracoid drilling, load was applied to the conjoined tendons at a rate of 120 mm/min and ultimate failure load, along with the failure mode, was recorded., Results: There was no significant difference between groups regarding load to failure. Mean load to failure in group 1 was 392 N; group 2, 459 N; and group 3, 506 N. The corresponding P values were .55, .74, and .20 for group 1 versus group 2, group 2 versus group 3, and group 1 versus group 3, respectively. However, the failure mode for the group with one 4-mm drill hole and the group with two 4-mm drill holes was coracoid fracture, whereas the group with one 2.4-mm drill hole showed 5 tears of the conjoined tendons and only 1 coracoid fracture (P = .015)., Conclusions: Although there was no significant difference regarding load-to-failure testing between groups, the failure mechanism analysis showed that one 2.4-mm drill hole led to less destabilization of the coracoid than one or two 4-mm drill holes., Clinical Relevance: Techniques with small, 2.4-mm drill holes might decrease the risk of severe iatrogenic fracture complications., (Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

There is an ever-increasing need to design better methods to selectively connect two molecules under mild aqueous conditions on a small scale. The process of finding such methods significantly relies on the employment of an appropriate assay. We report here a modular FRET-based assay to monitor such reactions and illustrate how the assay is used to monitor two particular reactions: native chemical ligation (NCL) and oxime ligation. For both reactions we show that by employing appropriately designed probes FRET measurements could be used to monitor the reaction's progress. We additionally demonstrate the usefulness of the developed probe system to study the mechanisms of the ligation reactions, for example, in monitoring the formation of a trimeric intermediate in the NCL reaction. Finally, we demonstrate that FRET measurements conducted in our system allow the quantification of the reaction yield and we show the application of our FRET-based assay to catalyst screening for the oxime ligation.

Background: Recent studies have described the presence of the anterolateral ligament (ALL). However, there is still no consensus regarding the anatomy of this structure with the topic controversially discussed. The aim of this study was to provide an anatomical description of the ligamentous structures on the anterolateral side of the knee with special emphasis on the ALL., Methods: Forty-four human cadaveric knees were dissected to reveal the ALL and other significant structures in the anterolateral compartment of the knee joint. The ALL was defined as a firm structure running in an oblique direction from the lateral femoral epicondyle to a bony insertion at the anterolateral tibia., Results: The ALL was identified in 45.5% (n=20) of the dissected knee joints. The structure originates together with the fibular collateral ligament (45%) or just posterior and proximal to it (55%). The ligament has an extra-capsular, anteroinferior, oblique course to the anterolateral tibia with a bony insertion between Gerdy's tubercle and the fibular head. The ALL had its greatest extend at 60° of knee flexion and maximal internal rotation., Conclusion: The ALL is a firm ligamentous structure in the anterolateral part of the knee present in 45.5% of the cases. Given the course and characteristics of this structure, a function in providing rotational stability by preventing internal rotation of the knee is likely., Clinical Relevance: The ALL might be an important stabilizer in the knee and may play a significant role in preventing excessive internal tibial rotation and subluxation of the knee joint., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Purpose: The purpose of this study was to determine the incidence of the "lateral femoral notch sign" in acute anterior cruciate ligament (ACL) tears and its correlation with lateral meniscal tears., Methods: Lateral plain radiographs and sagittal magnetic resonance images (each performed within 1 month following injury) of 500 patients with acute and arthroscopically confirmed ACL tears were retrospectively evaluated for depth, length and position of the "lateral femoral notch sign". The accompanying bone bruise was measured, as well. The correlation of the lateral femoral notch sign with high-risk and low-risk pivoting activities as well as with a lateral meniscus tear was evaluated., Results: A total of 26.4 % of the patients had a lateral femoral notch sign deeper than 2.0 mm with a mean depth of 2.8 ± 0.8 mm SD. All lateral femoral notches were situated near or slightly posterior to Blumensaat's line. ACL injuries sustained during high-risk pivoting sports were more prone to a lateral femoral notch sign than ACL injuries in low-risk pivoting sports (r = 0.107 vs r = -0.107). Of all patients with a lateral femoral notch sign, 40.2 % also had lateral meniscus tears. The correlation between the presence of the lateral femoral notch sign and lateral meniscus tears was statistically significant (p = 0.004)., Conclusion: In more than one-quarter of patients, plain radiographs may help to establish the diagnosis of an ACL tear. Further, a lateral femoral notch sign greater than 2.0 mm also correlates with lateral meniscus tears. Hence, the lateral femoral notch sign is a useful diagnostic tool in daily clinical practice., Level of Evidence: IV.

Purpose: The purpose of this study was to utilize a novel functional test system to facilitate determining the time of return to sports following ACL reconstruction., Methods: Sixty-nine patients with unilateral ACL reconstruction were included in this pilot study. All the patients performed a standardized test battery consisting of one- and two-legged stability tests, counter movement jumps, speedy jumps, plyometric jumps and a quick feed test. The first test was administered on average 170.7 ± 75.1 days post-operatively, and the retest was administered on average 239.1 ± 79.7 days post-operatively. The values of the subtests were compared with the normative data of healthy gender- and age-matched controls to determine the functional capacities of patients following ACL reconstruction., Results: After the first and second test, 15.9 and 17.4 % of the patients met the criteria for a "return to non-competitive sports". One patient fulfilled the criteria for a "return to competitive sports" after the second test battery. The most limiting factor was a poor LSI value of <90 % if the dominant leg was involved and <80 % if the non-dominant leg was involved., Conclusion: This test battery demonstrates that, in terms of neuromuscular abilities, most patients, compared to healthy controls, are most likely not ready for a safe return to sports, even 8 months post-operatively. This should be considered in the future to determine when it is safe to return to sports and should avoid a premature return to competitive sports., Level of Evidence: III.

Regeneration after surgery can be improved by the administration of anabolic growth factors. However, to locally maintain these factors at the site of regeneration is problematic. The aim of this study was to develop a matrix system containing human mesenchymal stem cells (MSCs) which can be applied to the surgical site and allows the secretion of endogenous healing factors from the cells. Calcium alginate gels were prepared by a combination of internal and external gelation. The gelling behaviour, mechanical stability, surface adhesive properties and injectability of the gels were investigated. The permeability of the gels for growth factors was analysed using bovine serum albumin and lysozyme as model proteins. Human MSCs were isolated, cultivated and seeded into the alginate gels. Cell viability was determined by AlamarBlue assay and fluorescence microscopy. The release of human VEGF and bFGF from the cells was determined using an enzyme-linked immunoassay. Gels with sufficient mechanical properties were prepared which remained injectable through a syringe and solidified in a sufficient time frame after application. Surface adhesion was improved by the addition of polyethylene glycol 300,000 and hyaluronic acid. Humans MSCs remained viable for the duration of 6 weeks within the gels. Human VEGF and bFGF was found in quantifiable concentrations in cell culture supernatants of gels loaded with MSCs and incubated for a period of 6 weeks. This work shows that calcium alginate gels can function as immobilization matrices for human MSCs.

Purpose: Posterior lateral meniscus root tears (PLMRTs) affect the intra-articular pressure distribution in the lateral compartment of the knee. The biomechanical consequences of these injuries are significantly influenced by the integrity of the meniscofemoral ligaments (MFLs). A newly introduced arthroscopic classification system for PLMRTs that takes MFL integrity into account has not yet been clinically applied but may be useful in selecting the optimal method of PLMRT repair., Methods: Prospective ACL reconstruction data were collected. Concomitant injuries of the lateral meniscus posterior horn were classified according to their shape and MFL status. The classifications were: type 1, avulsion of the root; type 2, radial tear of the lateral meniscus posterior horn close to the root with an intact MFL; and type 3, complete detachment of the posterior meniscus horn., Results: Between January 2011 and May 2012, 228 consecutive ACL reconstructions were included. Lateral and medial meniscus tears were identified in 38.2% (n = 87) and 44.7% (n = 102), respectively. Of the 87 lateral meniscus tears, 32 cases had PLMRTs; the overall prevalence of PLMRTs was 14% (n = 32). Two medial meniscus root tears were detected. All PLMRTs were classified according to the classification system described above, and the fixation procedure was adapted to the type of meniscus tear., Conclusion: The PLMRT tear is a common injury among patients undergoing ACL repair and can be arthroscopically classified into three different types. Medial meniscus root tears are rare in association with ACL tears. The PLMRT classification presented here may help to estimate the injury's impact on the lateral compartment and to identify the optimal treatment. These tears should not be overlooked, and the treatment strategy should be chosen with respect to the type of root tear., Level of Evidence: IV.

Studies aiming to understand the physicochemical properties of interstellar dust and the chemical reactions that occur on and in it have traditionally been the preserve of astronomical observation and experimental attempts to mimic astronomically relevant conditions in the laboratory. Increasingly, computational modelling in its various guises is establishing a complementary third pillar of support to this endeavour by providing detailed insights into the complexities of interstellar dust chemistry. Inherently, the basis of computational modelling is to be found in the details (e.g. atomic structure/composition, reaction barriers) that are difficult to probe accurately from observation and experiment. This bottom-up atom-based theoretical approach, often itself based on deeper quantum mechanical principles, although extremely powerful, also has limitations when systems become too large or complex. In this Perspective, after first providing a general background to the current state of observational-based knowledge, we introduce a number of computational modelling methods with reference to recent state-of-the-art studies, in order to highlight the capabilities of such approaches in this field. Specifically, we first outline the use of computational chemistry methods for dust nucleation, structure, and individual reactions on bare and icy dust surfaces. Later, we review kinetic modelling of networks of reactions relevant to dust chemistry and how to take into account quantum tunnelling effects in the low temperature reactions in the interstellar medium. Finally, we point to the future challenges that need to be overcome for computational modelling to provide even more detailed and encompassing perspectives on the nature and reaction chemistry of interstellar dust.

Background: The course of posttraumatic stress disorder (PTSD) is frequently and severely complicated by co-occurring alcohol use disorder (AUD), yet there are few reports of pharmacologic treatments for these comorbid conditions. The objective of this pilot study was to obtain a preliminary assessment of the efficacy and safety of topiramate in reducing alcohol use and PTSD symptoms in veterans with both disorders., Methods: This was a prospective 12-week, randomized, double-blind, placebo-controlled pilot trial of flexible-dose topiramate up to 300 mg/d in 30 veterans with PTSD and AUD. The primary outcome measure was frequency of drinking. Secondary outcomes consisted of other measures of alcohol use and PTSD symptom severity., Results: Within-group analyses showed that topiramate treatment was associated with significant reductions in frequency and amount of alcohol use and alcohol craving from baseline through week 12. Between-group analyses showed that topiramate reduced frequency of alcohol use and alcohol craving significantly more than placebo and tended to reduce drinking amount. Topiramate treatment was also associated with decreased PTSD symptom severity and tended to reduce hyperarousal symptoms compared with placebo. Topiramate transiently impaired learning and memory, with significant recovery by the end of treatment., Conclusions: These preliminary results indicate that in veterans with co-occurring PTSD and AUD, topiramate may be effective in reducing alcohol consumption, alcohol craving, and PTSD symptom severity-particularly hyperarousal symptoms. Topiramate was associated with transient cognitive impairment but was otherwise well tolerated., (Copyright © 2014 by the Research Society on Alcoholism.)

Objective: Video-EEG monitoring in the epilepsy monitoring unit (EMU) is a limited clinical resource. Knowledge of the predicting factors for length of stay (LOS) in the EMU may allow providers to more efficiently utilize EMU bed space., Methods: The records for all consecutive admissions to the EMU at the University of Colorado Hospital between December 1, 2010 and May 31, 2011 (n = 142) were retrospectively reviewed., Results: Univariate analyses focusing on variables known prior to admission showed that EMU LOS (in hours) was not significantly correlated with patient age, number of event types, or number of antiepileptic drugs at admission. Patients who were admitted to the EMU for event characterization had statistically significantly shorter average LOS than patients who had been admitted as a part of a presurgical evaluation. Patients who reported < = 1 seizure per week had a statistically significantly higher average LOS than patients who reported >= 1 seizure per day. These variables were also significantly predictive of total LOS (p < 0.0001 and p = 0.03, respectively) in multivariate analysis., Significance: Pre-admission clinical variables may predict EMU LOS. These factors could be used at the administrative level for maximum EMU resource utilization.

The interdisciplinary science of astrochemistry is 45 years of age, if we pinpoint its origin to have occurred when the first polyatomic molecules were detected in the interstellar gas. Since that time, the field has grown remarkably from an esoteric area of research to one that unites scientists around the globe. Almost 200 different molecules have been detected in the gas-phase of interstellar clouds, mainly by rotational spectroscopy, while dust particles and their icy mantles in colder regions can be probed by vibrational spectroscopy. Astrochemistry is exciting to scientists in a number of different fields. Astronomers are interested in molecular spectra from the heavens because such spectra are excellent probes of the physical conditions where molecules exist, while chemists are interested in the exotic molecules, their spectra, and the unusual chemical processes that produce and destroy them under conditions often very different from those on our home planet. Chemical simulations involving thousands of reactions are now used to calculate concentrations and spectra of interstellar molecules as functions of time. Even biologists share an interest in the subject, because the interstellar clouds of gas and dust, portions of which collapse to form stars and planetary systems, contain organic molecules that may become part of the initial inventory of new planets and may indeed be the precursors of life. An irresistible subject to its practitioners, astrochemistry is proving to be exciting to a much wider audience. In this perspective article, the field is first introduced, and the emphasis is then placed on the three environments in which chemistry occurs in the interstellar medium: the gas phase, the surfaces of bare dust particles, and the ice mantles that cover bare grains in cold dense interstellar clouds. What we do know and what we do not know is distinguished. The status of chemical simulations for a variety of interstellar sources having to do with stellar and planetary evolution is surveyed. An optimistic view of the future of astrochemistry ends the article.

The birth environment of the Sun will have influenced the physical and chemical structure of the pre-solar nebula, including the attainable chemical complexity reached in the disk, important for prebiotic chemistry. The formation and distribution of complex organic molecules (COMs) in a disk around a T Tauri star is investigated for two scenarios: (i) an isolated disk, and (ii) a disk irradiated externally by a nearby massive star. The chemistry is calculated along the accretion flow from the outer disk inwards using a comprehensive network which includes gas-phase reactions, gas-grain interactions, and thermal grain-surface chemistry. Two simulations are performed, one beginning with complex ices and one with simple ices only. For the isolated disk, COMs are transported without major chemical alteration into the inner disk where they thermally desorb into the gas reaching an abundance representative of the initial assumed ice abundance. For simple ices, COMs can efficiently form on grain surfaces under the conditions in the outer disk. Gas-phase COMs are released into the molecular layer via photodesorption. For the irradiated disk, complex ices are also transported inwards; however, they undergo thermal processing caused by the warmer conditions in the irradiated disk which tends to reduce their abundance along the accretion flow. For simple ices, grain-surface chemistry cannot efficiently synthesise COMs in the outer disk because the necessary grain-surface radicals, which tend to be particularly volatile, are not sufficiently abundant on the grain surfaces. Gas-phase COMs are formed in the inner region of the irradiated disk via gas-phase chemistry induced by the desorption of strongly bound molecules such as methanol; hence, the abundances are not representative of the initial molecular abundances injected into the outer disk. These results suggest that the composition of comets formed in isolated disks may differ from those formed in externally irradiated disks with the latter composed of more simple ices.

In this closing article, we first introduce the topics of dust and ice chemistry and their role in astrochemistry. We then discuss the invited contributions and discussions concerning these topics, dividing the papers into groupings by subject: (i) astronomical sources, (ii) basic properties of dust, (iii) processes on bare grains, (iv) processes on and in ice mantles, and (v) complex organic molecules. A sample of poster contributions is included in the text, when they complement the discussion. The article ends with some suggestions for future research.

The pure rotation spectrum of deuterated cyanamide was recorded at frequencies from 118 to 649 GHz, which was complemented by measurement of its high-resolution rotation-vibration spectrum at 8-350 cm(-1). For D2NCN the analysis revealed considerable perturbations between the lowest Ka rotational energy levels in the 0(+) and 0(-) substates of the lowest inversion doublet. The final data set for D2NCN exceeded 3000 measured transitions and was successfully fitted with a Hamiltonian accounting for the 0(+) ↔ 0(-) coupling. A smaller data set, consisting only of pure rotation and rotation-vibration lines observed with microwave techniques was obtained for HDNCN, and additional transitions of this type were also measured for H2NCN. The spectroscopic data for all three isotopic species were fitted with a unified, robust Hamiltonian allowing confident prediction of spectra well into the terahertz frequency region, which is of interest to contemporary radioastronomy. The isotopic dependence of the determined inversion splitting, ΔE = 16.4964789(8), 32.089173(3), and 49.567770(6) cm(-1), for D2NCN, HDNCN, and H2NCN, respectively, is found to be in good agreement with estimates from a simple reduced quartic-quadratic double minimum potential.

An emerging theme in modern astrophysics is the connection between astronomical observations and the underlying physical phenomena that drive our cosmos. Both the mechanisms responsible for the observed astrophysical phenomena and the tools used to probe such phenomena-the radiation and particle spectra we observe-have their roots in atomic, molecular, condensed matter, plasma, nuclear and particle physics. Chemistry is implicitly included in both molecular and condensed matter physics. This connection is the theme of the present report, which provides a broad, though non-exhaustive, overview of progress in our understanding of the cosmos resulting from recent theoretical and experimental advances in what is commonly called laboratory astrophysics. This work, carried out by a diverse community of laboratory astrophysicists, is increasingly important as astrophysics transitions into an era of precise measurement and high fidelity modeling.