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A previously unreported series of hexagonal-perovskite-based Rb-oxoiridates, Rb 5 Ir 2 O 9 , Rb 7 Ir 3 O 12 , and Rb 12 Ir 7 O 24 , have been synthesized and structurally analyzed via N 2 -protected single-crystal X-ray diffraction (SC-XRD). These materials exhibit different 1D Ir n O 3( n +1) chain fragments along their c axes. IrO 6 octahedra and RbO x ( x = 6, 8, and 10) polyhedra are their basic building blocks. The IrO 6 octahedra are linked via face-sharing, forming Ir 2 O 9 dimers, Ir 3 O 12 trimers, and Ir 7 O 24 heptamers. The nonmagnetic RbO x ( x = 6, 8, and 10) polyhedra serve as both bridging units and spacers. Temperature-dependent SC-XRD shows all three to display positive thermal expansion and rules out structural transitions from their triangular symmetries down to 100 K. Density functional theory results suggest semiconducting-like behavior for the title compounds. The flatness of the electronic bands and our structural analysis are of potential interest for understanding and designing 1D quantum materials.

In lead(II) halide compounds including virtually all lead halide perovskites, the Pb 2+ 6s lone pair results in distorted octahedra, in accordance with the pseudo-Jahn-Teller effect, rather than generating hemihedral coordination polyhedra. Here, in contrast, we report the characterization of an organic-inorganic hybrid material consisting of one-dimensional edge-sharing chains of Pb-Br square pyramids, separated by [Mn(DMF) 6 ] 2+ (DMF = dimethylformamide) octahedra. Molecular orbital analysis and density-functional theory calculations indicate that square pyramidal coordination about Pb 2+ results from the occupancy of the empty ligand site by a Pb 2+ lone pair that has both s and p orbital character rather than the exclusively 6s lone pair. These results demonstrate that a Pb 2+ lone pair can be exploited to behave like a ligand in lead halide compounds, greatly expanding the realm of possible lead halide materials to include extended solids with nonoctahedral coordination environments.

While elemental substitution is the most common way of tuning properties in solid state compounds, this approach can break down in fantastic ways when the stability range of a structure type is exceeded. In this article, we apply the Frustrated and Allowed Structural Transitions (FAST) principle to understand how structural complexity, in this case incommensurate modulations, can emerge at the composition limits of one common intermetallic framework, the BaAl 4 type. While the Dy-Ga binary intermetallic system contains no phases related to the BaAl 4 archetype, adding Cu to form a ternary system creates a composition region that is rich in such phases, including some whose structures remain unknown. We begin with an analysis of electronic and atomic packing issues faced by the hypothetical BaAl 4 -type phase DyGa 4 and a La 3 Al 11 -type variant (in which a fraction of Ga 2 pairs are substituted by single Ga atoms). Through an inspection of its electronic density of states (DOS) distribution and DFT-Chemical Pressure (CP) scheme, we see that the stability of BaAl 4 -type DyGa 4 is limited by an excess of electrons and overly large coordination environments around the Dy atoms, with the latter factor being particularly limiting. The inclusion of Cu into the system is anticipated to soothe both issues through the lowering of the valence electron count and the release of positive CPs between atoms surrounding the Dy atoms. With this picture in mind, we then move to an experimental investigation of the Dy-Cu-Ga system, elucidating the structure of Dy(Cu 0.18 Ga 0.82 ) 3.71(1) . In this compound, the BaAl 4 type is subject to a 2D incommensurate modulation ( q 1 = 0.31 a* + 0.2 b* , q 2 = 0.31 a* - 0.2 b* ), which can be modeled in the (3+2)D superspace group Pmmm ( αβ 0)000( α-β 0)000. The resulting structure solution contains blocks of the La 3 Al 11 type, with the corners of these domains serving to shrink the Dy coordination environments. These results highlight how the addition of a well-chosen third element to a binary system with a missing-but plausible-compound (BaAl 4 -type DyGa 4 ) can bring it to the cusp of stability with intriguing structural consequences.

Incommensurate order, in which two or more mismatched periodic patterns combine to make a long-range ordered yet aperiodic structure, is emerging as a general phenomenon impacting the crystal structures of compounds ranging from alloys and nominally simple salts to organic molecules and proteins. The origins of incommensurability in these systems are often unclear, but it is commonly associated with relatively weak interactions that become apparent only at low temperatures. In this article, we elucidate an incommensurate modulation in the intermetallic compound PdBi that arises from a different mechanism: the controlled increase of entropy at higher temperatures. Following the synthesis of PdBi, we structurally characterize two low-temperature polymorphs of the TlI-type structure with single crystal synchrotron X-ray diffraction. At room temperature, we find a simple commensurate superstructure of the TlI-type structure (comm-PdBi), in which the Pd sublattice distorts to form a 2D pattern of short and long Pd-Pd contacts. Upon heating, the structure converts to an incommensurate variant (incomm-PdBi) corresponding to the insertion of thin slabs of the original TlI type into the superstructure. Theoretical bonding analysis suggests that comm-PdBi is driven by the formation of isolobal Pd-Pd bonds along shortened contacts in the distorted Pd network, which is qualitatively in accord with the 18- n rule but partially frustrated by the population of competing Bi-Bi bonding states. The emergence of incomm-PdBi upon heating is rationalized with the DFT-Cemical Pressure (CP) method: the insertion of TlI-type slabs result in regions of higher vibrational freedom that are entropically favored at higher temperatures. High-temperature incommensurability may be encountered in other materials when bond formation is weakened by competing electronic states, and there is a path for accommodating defects in the CP scheme.

To the experienced molecular chemist, predicting the geometries and reactivities of a system is an exercise in balancing simple concepts such as sterics and electronics. In this Article, we illustrate how recent theoretical developments can give this combination of concepts a similar predictive power in intermetallic chemistry through the anticipation and discovery of structural complexity in the nominally MnP-type compound IrSi. Analysis of the bonding scheme and DFT-Chemical Pressure (CP) distribution of the reported MnP-type structure exposes issues pointing toward new structural behavior. The placement of the Fermi energy below an electronic pseudogap indicates that this structure is electron-poor, an observation that can be traced via the 18- n rule to the structure's Ir-Ir connectivity. In parallel with this, the structure's CP scheme highlights facile paths of atomic motion that could enable a structural response to this electronic deficiency. Combined, these analyses suggest that IrSi may adopt a more complex structure than previously recognized. Through synthesis and detailed structural investigation of this phase, we confirm this prediction: single-crystal X-ray diffraction reveals an incommensurately modulated structure with the (3+1)D superspace group P 2 1 / n (0 βγ )00 and q ≈ -0.22 b* + 0.29 c* . The structural modulations increase the average number of Ir-Ir bonds to nearly match the 18- n expectations of the phase through Ir-Ir trimerization along negative CPs with the incommensurability arising from the difficulty of contracting and stretching the Ir-Ir contacts in a regular pattern without expanding the structure along directions of negative Si-Si CP. Integrating these results with prior analyses of related systems points to a simple guideline for materials design, the Frustrated and Allowed Structural Transitions (FAST) principle: the ease with which competing structural phenomena can be experimentally realized is governed by the degree to which they are supported by the coordination of the atomic packing and electronic factors.

The structures and properties of intermetallic phases are intimately connected to electron count; unfavorable electron counts can result in structural rearrangements or new electrical or magnetic behavior when no such transformation is available. The compound PtGa 2 appears to teeter on the border between these two scenarios with its two polymorphs: a cubic fluorite type form (c-PtGa 2 ) and a complex tetragonal superstructure (t-PtGa 2 ) whose Pt-Pt connectivity aligns with the 18- n electron counting rule. Here, we investigate the factors underlying this polymorphism. Electronic structure calculations show that the transition to t-PtGa 2 opens a pseudogap at the Fermi energy that can be traced to Pt-Pt isolobal bond formation, in line with the 18- n bonding scheme. Conversely, DFT-chemical pressure (CP) analysis reveals a network of positive local pressures along Pt-Ga contacts, requiring that the c-PtGa 2 to t-PtGa 2 transition follows tightly concerted atomic motions. Experimentally, a series of samples with varying Pt:Ga ratios were synthesized to examine the stability ranges of the polymorphs. Ga-poor samples yield exclusively the cubic polymorph over the full range of temperatures studied, which can be correlated to the enhanced incorporation of interstitial Pt atoms (at points of negative pressure in the CP scheme). At more Ga-rich compositions, however, t-PtGa 2 emerges as a low-temperature form. In these samples, the t-PtGa 2 to c-PtGa 2 transition is found to be reversible, but with a large hysteresis that in single crystals can exceed 100 °C. Together, the theoretical and experimental results indicate that the c-PtGa 2 phase is buttressed at its unfavorable electron count by the interstitial atoms and networks of positive CPs that restrict atomic motion, suggesting more general strategies for achieving exotic electronic structures in intermetallic materials.

This paper reports the results of a series of 5 patients who underwent closure of persistent bronchopleural fistula using extrathoracic muscle flaps over a 6-year period. All patients had failed more conservative treatment. The surgeries were one- or two-stage procedures performed with the collaboration of cardiovascular and reconstructive surgical staffs. There were no associated mortalities. The muscle flaps utilized were the latissimus dorsi, serratus anterior, pectoralis major, pectoralis minor, and trapezius. The results have been encouraging and allowed the complete closure of the bronchopleural fistula in the majority of patients. The authors present the best management of this serious disease, as well as its pathophysiology and clinical aspects.

Background: Correction of partial anomalous pulmonary venous connection to the superior vena cava (SVC) is often complicated by sinus node dysfunction and occasional pacemaker insertion., Methods: Between 1964 and 1994 40 patients, ranging from 14 months to 52 years old, underwent an operative approach designed to minimize trauma to the sinus node and its blood supply. The SVC was transected and oversewn above the highest anomalous vein. The anomalous pulmonary veins were redirected across a sinus venosus atrial septal defect (33 patients) or a surgically created atrial septal defect (7 patients) into the left atrium. The atrial septal defect rim was coapted to the intracardiac SVC orifice in 23 patients. An intracardiac baffle was used in 17 patients. The cephalad SVC stump was anastomosed to the right atrial appendage. The origin of the pulmonary veins draining into the SVC was right upper lobe (all patients), right middle lobe (33 patients), and the entire right lung (9 patients)., Results: One 31-year-old woman died of severe pulmonary hypertension. An early technical error resulted in one symptomatic SVC obstruction. All patients remained well over follow-up (6 months to 30 years), without residual intracardiac defects. Sick sinus syndrome developed late in only 1 patient (2.5%). No patient has required a pacemaker., Conclusions: The very low incidence of late arrhythmias with cavoatrial reconstruction is most encouraging.

Early surgical intervention for atrial myxomas mitigates morbidity and usually offers cure. The operative approach to resect these tumors is controversial. The purpose of this study was to review our experience with the biatrial approach between 1964 and 1994. The location of the myxoma was left atrium in 17 and right atrium in 3. Mean preoperative New York Heart Association functional classification was 2.7. Surgical approach to the tumor was biatrial in all patients. There were no perioperative strokes, myocardial infarctions, or deaths. Mean follow-up was 7.5 years (range, 2 mo to 27 years) with a postoperative New York Heart Association functional classification of 1.4. One late death occurred, which was unrelated to the myxoma. Advantages of biatrial approach include (1) definition of tumor pedicle by direct visualization, (2) minimal manipulation of the tumor, (3) adequate margins of excision, (4) inspection of all heart chambers, and (5) secure closure of the atrial septal defect. Long-term follow-up demonstrates the efficacy of this operative approach to atrial myxomas.

We analyzed our experience at a university medical center from 1977 to 1990 to assess our success in using esophagoscopy and related treatments for removing esophageal impactions. There were 157 episodes of impaction in 150 patients, consisting of 39 pediatric and 111 adult patients. In the pediatric cases, foreign bodies were most often the cause of impaction, while adult cases were usually caused by food or bones. Esophagoscopy was performed successfully in 32 of 34 pediatric patients in which it was attempted; there was only one complication. Other forms of therapy that were infrequently tried met with variable results. Esophagoscopy was successful in removing the impaction in 104 of 109 attempts in adults. Two perforations occurred, with one resulting in death. Various other methods achieved success in the remaining patients. The data suggest that esophageal impaction can be treated successfully by endoscopy with very low morbidity and mortality.

Mutations in the gene coding for the p53 tumor suppressor protein are common in a variety of human cancers. To assess the role of a putative mutated p53 protein in human lung cancer, a monoclonal antibody recognizing it was used in an immunoperoxidase detection system. A total of 114 cases of Stage I and II adenocarcinomas and squamous cell carcinomas were studied. The staining pattern was always intranuclear and heterogeneous. When the median or mean survival time was compared between cases, p53 accumulation had a statistically significant negative prognostic value. This was supported by a Kaplan-Meier survival plot of p53 producers and nonproducers. In 7 of 24 Stage II cases that were negative for p53 in the primary tumor, metastatic regional lymph nodes were p53-positive. These latter cases had greatly reduced survival times. Thus, p53 accumulation in primary tumors (and regional lymph nodes) may identify a subgroup of lung cancer patients with a prognosis of more aggressive disease.

Despite appropriate antibiotics and pleural drainage, the condition of some children with empyema fails to improve. In a 5-year period, 10 children ranging in age from 2 to 16 years underwent lung decortication for a refractory, symptomatic empyema, which had developed 3 to 5 weeks after an initial pneumonic infiltrate. Responsible organisms included beta-hemolytic streptococci, Haemophilus influenzae, or Streptococcus pneumoniae in 6 children. Negative cultures were found in 4 children. The initial computed tomographic scan of the chest in 4 of 8 patients showed more than 75% limitation of lung expansion by the contents of the empyema cavity. In 4 other patients, an extensive pleural peel was seen on initial computed tomographic scan of the chest. Several studies also showed cystic lesions in the collapsed lung. Multiple computed tomographic scans in 3 patients confirmed the lack of clinical and chest roentgenographic improvement with conservative therapy. At decortication in each, the visceral and parietal pleural peel was completely removed, freeing the trapped lung. Two patients also had a concomitant lobectomy for a necrotic right upper lobe (1 patient) and left lower lobe (1). Clinical improvement was marked, with return of temperature, white blood cell count, and appetite to normal. Postoperative morbidity was minimal. Analysis of these patients in whom traditional conservative therapy failed suggested that the initial management during the early exudative phase was often delayed and was not aggressive enough from the standpoint of pleural drainage.(ABSTRACT TRUNCATED AT 250 WORDS)

After Norwood's initial report of successful first-stage palliation of hypoplastic left heart syndrome in neonates, the occurrence of distal aortic obstructions, shunt problems, and late deaths have led to modifications in the surgical technique. Between January 1986 and December 1987, 12 neonates from three to 16 days old underwent stage I palliation with the same objectives. An open atrial septectomy was always performed. The pulmonary artery bifurcation was transected from the main pulmonary artery and closed with an aortic homograft patch. The aortotomy was begun 2 cm below the patent ductus arteriosus insertion and extended across the transverse arch and down the ascending aorta. The neoaorta was constructed using the hypoplastic ascending aorta-transverse aortic arch, the main pulmonary artery, and an aortic homograft augmentation patch. The homograft is hemostatic and pliable, and molds well in forming the neoaorta. A 4-mm shunt was inserted between the right innominate artery and the right pulmonary artery in 5 patients and the neoaorta and the pulmonary artery bifurcation patch in 7 patients. The early systemic oxygen saturation was optimized at 75% to 80% with hyperventilation, high concentration of inspired oxygen, sodium bicarbonate, and the frequent use of vasopressors to maintain an arterial blood pressure of 65 to 75 mm Hg. Two patients (17%) died early after operation; 1 had severe right ventricular dysfunction and both had severe tricuspid regurgitation. There were 2 late deaths at 7 and 13 months, of sepsis and hypoxia. The 8 survivors (67%) continue to do well over follow-up. The preoperative tricuspid regurgitation has remained stable in 3 survivors and disappeared in 2 survivors.(ABSTRACT TRUNCATED AT 250 WORDS)

Partial anomalous pulmonary venous connection to the right side of the heart often complicates surgery for atrial septal defects. Between 1964 and 1987, 39 patients, ranging from 2 to 52 years old, underwent repair of partial anomalous pulmonary venous connection. At least one anomalous pulmonary vein arose from the right upper lobe in 38 patients and right middle lobe in 30 patients and connected to the superior vena cava in 28 patients and the right atrium only in 11 patients. An atrial septal defect was present in 32 patients (82%). Patients who had partial anomalous pulmonary venous connection to the superior vena cava-right atrium junction, the right atrium or both were treated by septal translocation (two patients) or patch redirection of the anomalous pulmonary venous flow to the left atrium through a native atrial septal defect (eight patients) or a surgically created atrial septal defect in two patients with intact atrial septum. For partial anomalous pulmonary venous connection to the high superior vena cava (27 patients), the superior vena cava was transected and oversewn above the anomalous veins. The anomalous pulmonary venous flow was redirected through the proximal superior vena cava into the left atrium across a sinus venous atrial septum defect (22 patients) or a surgically created atrial septal defect in five patients with intact atrial septum. The atrial septal defect was coapted to the intracardiac orifice of the superior vena cava, and the distal superior vena cava was anastomosed to the right atrial appendage. One 31-year-old woman with severe pulmonary hypertension died early and was the only death in the series. A technical error early in the series resulted in one symptomatic superior vena cava obstruction. Only one patient remains in sick sinus syndrome late. All patients remain well over long follow-up (1 to 24 years). Postoperative catheterization or echocardiography has revealed no intracardiac defects, pulmonary venous obstruction, or superior vena cava obstruction (except the one technical error). Correction of partial anomalous pulmonary venous connection should be individualized according to the site of connection of the anomalous pulmonary veins and the location of the atrial defect to minimize undesirable postoperative sequelae often associated with other methods of repair.

The records of all 380 adult patients receiving cardiac pacemakers at West Virginia University in the 15-year period ending January 1, 1977, were reviewed. The five-year survival rate was 58 per cent and the 10 year, 38 per cent with a median survival of 74 months. Life expectancy approached life-table curves if the mortality during the initial year was ignored. Although the younger patients lived the longest, their expected survival was reduced more than in the older patients. The need for a pacemaker in a young person implies serious life-shortening consequences. Unlike reports in the literature, patients with sinoatrial disease fared worse than those with A-V block.

Acute ischemia of the upper limb is commonly caused by trauma and embolic arterial occlusion. However, primary atherosclerotic thrombosis is found infrequently and concern regarding its incidence, recognition, and treatment prompted a review of our clinical experience. Of 36 patients with acute ischemia of the upper limb, 17 (47.2 per cent) had embolic occlusion, 9 (25 per cent) iatrogenic thrombosis in the brachial artery, and 10 (27.8 per cent) primary arterial thrombosis. Of the total group, noncardiac arterial emboli (two patients) and primary atherosclerotic thrombosis (six patients) accounted for 8 of 36 (22.2 per cent) ischemic limbs. Including 2 additional patients who had atherosclerotic thrombosis associated with trauma, the total number represented 10 of 36 (27.8 per cent). An aggressive approach to the undiagnosed patient with acute ischemia of the upper limb is warranted, including the use of arteriography in most cases. In patients with iatrogenic thrombosis in the brachial artery, we believe that the routine use of intraoperative arteriograms may improve the operative results.

Young age, low weight, and the requirement for transannular patch reconstruction of the right ventricular outflow tract (RVOT) are thought to adversely affect intracardiac repair of tetralogy of Fallot. Forty patients underwent complete repair between January, 1984, and January, 1987. Only infants with pulmonary atresia, complete atrioventricular canal, or coronary artery anomalies were shunted initially. The malalignment ventricular septal defect was closed with a Dacron patch. Infundibular resection was minimized. All atrial communications were left open. Thirty-four patients (85%) had a transannular RVOT patch, and 2 patients (5%) had a nontransannular patch. All 10 infants weighing 3.4 to 9.6 kg had a transannular RVOT patch at 7 weeks to 12 months of age. An RVOT patch was used in 26 of 30 children operated on between 1 and 6 years of age (median age, 24 months). No patient undergoing intracardiac repair died. Postoperative RVOT pullback gradients were between 0 and 35 mm Hg (mean, 18.5 mm Hg). Postoperative pulmonary artery saturation (mean, 73%) did not reveal any residual ventricular septal defect. The right ventricular/arterial pressure ratio was always less than 0.6 (mean, 0.4). All children are doing well at follow-up from two to 37 months. Serial echocardiograms reveal no residual ventricular septal defect and only 1 moderate RVOT gradient. Follow-up cardiac catheterization in 15 patients revealed no residual ventricular septal defect and RVOT gradients between 5 and 35 mm Hg. The right ventricular/left ventricular pressure ratio was always less than 0.6 (mean, 0.48). The early and late results justify continued primary repair of tetralogy of Fallot in symptomatic children, regardless of age or weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Intralobar pulmonary sequestration is an uncommon but distinct clinical entity that may be the unrecognized cause of recurrent pulmonary infections. Between 1967 and 1987, 10 patients, ranging in age from 5 to 39 years, were found to have an intralobar sequestration. Nine patients (90%) had a history of recurrent pulmonary infections, chronic cough, and intermittent fevers. One patient was asymptomatic. Many patients had been treated with antibiotics on numerous occasions. The delay in diagnosis varied between 3 months and 7 years (mean delay, 1.5 years). The chest roentgenogram was abnormal in all patients. The intralobar sequestration was present in the left lower lobe in 7 patients and the right lower lobe in 3 patients. Bronchography was abnormal in 4 patients in whom it was done. Bronchoscopy was performed in 7 patients, but it was only helpful in excluding other diagnoses. Preoperative thoracic arteriography in 9 patients visualized the systemic arterial supply from the thoracic or abdominal aorta to the intralobar sequestration and helped prevent any catastrophic surgical bleeding. A lobectomy was performed in 9 patients and a segmentectomy in 1 patient without morbidity or mortality. In patients with recurrent infections in the same lower lobe, a high index of suspicion for an intralobar sequestration should prompt early diagnostic arteriography and, if confirmed, early operative intervention.

From 1960 to 1978, 80 patients from 2 weeks to 49 years of age underwent operations for coarctation of the aorta. Twelve patients were under 3 months old, and 68 were older. All of the infants presented with congestive heart failure and multiple cardiac defects. In the older patients, hypertension was the most common presenting symptom; 14 were asymptomatic. All patients under 3 months old received primary correction. Seven (58%) died of complications associated with other cardiac anomalies. In the older group, there was 59 primary reconstructions, six interposition grafts, and three other procedures. There were two deaths in this group. There were three re-explorations, two for bleeding and one for false aneurysm at the suture line. Seven older patients exhibited paradoxical hypertension: three developed abdominal symptoms and two required laparotomy. Three patients originally operated on during infancy developed recurrent coarctation with reoperation in two. Nine of the older patients had chronic hypertension, all of whom were operated on after age 15. Surgical correction of coarctation in infants carries a high mortality rate secondary to associated defects. The operative mortality rate in older patients is minimal, and correction should be undertaken early to prevent the long-standing complications of hypertension.

A controlled prospective study of forty-two patients shows it is feasible to correct gastroesophageal reflux complicating sliding hiatal hernia by modifying Allison's repair, using the technic of vertical mattress sutures and Dacron pledgets to approximate the crura and reattach the esophagus to the narrowed hiatus. There was no operative mortality and minimal morbidity. The follow-up period ranges from six to eighty-two months (mean, 38.5 months). One recurrence was noted clinically and verified by esophagogram, esophagoscopy, and motility studies. The remainder have no symptoms of gastroesophageal reflux, and no recurrence has been seen on repeat esophagograms.

The surgical management of 15 patients with partial anomalous pulmonary venous connection (PAPVC) to the high superior vena cava (SVC) is described. This new technique redirects the anomalous pulmonary venous flow into the left atrium through the cardiac end of the SVC, transected and oversewn above the anomalous pulmonary vein or veins, by coaptation of the atrial septal defect (or of the surgically created septal defect in patients with an intact atrial septum) to the intracardiac orifice of the SVC. Normal SVC-right atrial flow is reconstituted by atriocavoplasty to the cephalad portion of the transected SVC. A 31-year-old woman with severe pulmonary hypertension died early in the series; this was the only death. Surviving patients enjoy full activity. Except for one symptomatic SVC obstruction due to technical error (since relieved), this technique has achieved total correction of these congenital defects with marked reduction in the undesirable postoperative sequelae often associated with other methods of repair.