Resonant Inelastic X-Ray Scattering Reveals Hidden Local Transitions of the Aqueous OH Radical.

Resonant inelastic x-ray scattering (RIXS) provides remarkable opportunities to interrogate ultrafast dynamics in liquids. Here we use RIXS to study the fundamentally and practically important hydroxyl radical in liquid water, OH(aq). Impulsive ionization of pure liquid water produced a short-lived population of OH(aq), which was probed using femtosecond x-rays from an x-ray free-electron laser. We find that RIXS reveals localized electronic transitions that are masked in the ultraviolet absorption spectrum by strong charge-transfer transitions-thus providing a means to investigate the evolving electronic structure and reactivity of the hydroxyl radical in aqueous and heterogeneous environments. First-principles calculations provide interpretation of the main spectral features.

Hydrolysed egg displays strong decrease in allergenicity and is well tolerated by egg-allergic patients.

Food allergies are believed to be on the rise, and currently, management relies on the avoidance of the food. Hen's egg allergy is after cow's milk allergy the most common food allergy; eggs are used in many food products and thus difficult to avoid. A technological process using a combination of enzymatic hydrolysis and heat treatment was designed to produce modified hen's egg with reduced allergenic potential. Biochemical (SDS-PAGE, Size exclusion chromatography and LC-MS/MS) and immunological (ELISA, immunoblot, RBL-assays, animal model) analysis showed a clear decrease in intact proteins as well as a strong decrease of allergenicity. In a clinical study, 22 of the 24 patients with a confirmed egg allergy who underwent a double-blind food challenge with the hydrolysed egg remained completely free of symptoms. Hydrolysed egg products may be beneficial as low-allergenic foods for egg-allergic patients to extent their diet.

Attosecond-pump attosecond-probe x-ray spectroscopy of liquid water.

Attosecond-pump/attosecond-probe experiments have long been sought as the most straightforward method for observing electron dynamics in real time. Although there has been much success with overlapped near-infrared femtosecond and extreme ultraviolet attosecond pulses combined with theory, true attosecond-pump/attosecond-probe experiments have been limited. We used a synchronized attosecond x-ray pulse pair from an x-ray free-electron laser to study the electronic response to valence ionization in liquid water through all x-ray attosecond transient absorption spectroscopy (AX-ATAS). Our analysis showed that the AX-ATAS response is confined to the subfemtosecond timescale, eliminating any hydrogen atom motion and demonstrating experimentally that the 1b1 splitting in the x-ray emission spectrum is related to dynamics and is not evidence of two structural motifs in ambient liquid water.

Considerations for realistic atmospheric environments: An application to corrosion testing.

Measured salt compositions in dust collected over roughly the last decade from surfaces of in-service stainless-steel alloys at four locations around the United States are presented, along with the predicted brine compositions that would result from deliquescence of these salts. The salt compositions vary greatly from ASTM seawater and from laboratory salts (i.e., NaCl or MgCl2) commonly used on corrosion testing. The salts contained relatively high amounts of sulfates and nitrates, evolved to basic pH values, and exhibited deliquescence relative humidity values (RH) higher than seawater. Additionally, inert dust in components were quantified and considerations for laboratory testing are presented. The observed dust compositions are discussed in terms of the potential corrosion behavior and are compared to commonly used accelerated testing protocols. Finally, ambient weather conditions and their influence on diurnal fluctuations in temperature (T) and RH on heated metal surfaces are evaluated and a relevant diurnal cycle for laboratory testing a heated surface has been developed. Suggestions for future accelerated tests are proposed that include exploration of the effects of inert dust particles on atmospheric corrosion, chemistry considerations, and realistic diurnal fluctuations in T and RH. Understanding mechanisms in both realistic and accelerated environments will allow development of a corrosion factor (i.e., scaling factor) for the extrapolation of laboratory-scale test results to real world applications.

Physical and chemical properties of sea salt deliquescent brines as a function of temperature and relative humidity.

Thermodynamic modeling has been used to predict chemical compositions of brines formed by the deliquescence of sea salt aerosols. Representative brines have been mixed, and physical and chemical properties have been measured over a range of temperatures. Brine properties are discussed in terms of atmospheric corrosion of austenitic stainless steel, using spent nuclear fuel dry storage canisters as an example. After initial loading with spent fuel, during dry storage, the canisters cool over time, leading to increased surface relative humidities and evolving brine chemistries and properties. These parameters affect corrosion kinetics and damage distributions, and may offer important constraints on the expected timing, rate, and long-term impacts of canister corrosion.

Revealing the exciton fine structure of PbSe nanocrystal quantum dots using optical spectroscopy in high magnetic fields.

We measure the photoluminescence lifetime τ of excitons in colloidal PbSe nanocrystals (NCs) at low temperatures to 270 mK and in high magnetic fields to 15 T. For all NCs, τ increases sharply below 10 K but saturates by 500 mK. In contrast to the usual picture of well-separated "bright" and "dark" exciton states (found, e.g., in CdSe NCs), these dynamics fit remarkably well to a system having two exciton states with comparable--but small--oscillator strengths that are separated by only 300-900 µeV depending on NC size. Importantly, magnetic fields reduce τ below 10 K, consistent with field-induced mixing between the two states. Magnetic-circular dichroism studies reveal exciton g factors from 2-5, and magnetophotoluminescence shows >10% circularly polarized emission.

Observation of the fastest chemical processes in the radiolysis of water.

Elementary processes associated with ionization of liquid water provide a framework for understanding radiation-matter interactions in chemistry and biology. Although numerous studies have been conducted on the dynamics of the hydrated electron, its partner arising from ionization of liquid water, H2O+, remains elusive. We used tunable femtosecond soft x-ray pulses from an x-ray free electron laser to reveal the dynamics of the valence hole created by strong-field ionization and to track the primary proton transfer reaction giving rise to the formation of OH. The isolated resonance associated with the valence hole (H2O+/OH) enabled straightforward detection. Molecular dynamics simulations revealed that the x-ray spectra are sensitive to structural dynamics at the ionization site. We found signatures of hydrated-electron dynamics in the x-ray spectrum.

X-ray absorption spectroscopy of liquid methanol microjets: bulk electronic structure and hydrogen bonding network.

We have measured the X-ray absorption (XA) spectrum of liquid (298 K) methanol at the oxygen and carbon K edges. The 4a(1) orbital at the O K edge exhibits a pronounced sensitivity to the formation of intermolecular hydrogen bonds, with significant differences observed between the vapor and bulk spectra, whereas the C K edge reveals only subtle corresponding spectral changes. Comparison with DFT computed spectra of model methanol clusters indicates that the bulk liquid comprises long chains (n > 6) and rings of hydrogen-bonded monomers.

Tap water scald burns in children.

Tap water scald burns account for 7% to 17% of all childhood scald burns that require hospitalization. Often the burns are severe and disabling. Toddlers and preschool children are the most frequent victims. In 45% of the injuries, the unsupervised victim or peer turned on the tap water; in 28% the cause was abuse. Eighty percent of the homes tested had unsafe bathtub water temperatures of 54 C (130 F) or greater, exposing the occupants to the risk of full-thickness scald with 30-second exposure to hot water. Such burns may be prevented passively by limiting household water temperatures to less than 52 C (125 F). New water heaters could be preset at this temperature and families could be taught to turn down the temperature on existing units.

Limited surgery for lower-segment Hirschsprung's disease.

OBJECTIVE: To determine if rectal myectomy is an effective treatment for a specific group of patients with Hirschsprung's disease. DESIGN: Retrospective series with follow-up of 6 to 132 months (mean follow-up, 37.1 months). SETTING: Children's hospital. PATIENTS: Fourteen children aged 2 to 14 years with chronic constipation and nondiagnostic barium enema contrast study findings. INTERVENTION: Posterior rectal myectomy. MAIN OUTCOME MEASURES: Laxative use, frequency of stools, incidence of soiling or incontinence, and patient's assessment of improvement. RESULTS: The conditions of all 14 patients improved regardless of the presence of ganglion cells in the myectomy specimen; there were six excellent, six good, and two fair assessments. laxatives were used intermittently by seven of 14 patients. No patients complained of incontinence or soiling. CONCLUSIONS: Rectal myectomy is an effective, less-extensive operation that should be considered for older children with Hirschsprung's disease.

Foreign bodies within a Meckel's diverticulum.

Although complications of Meckel's diverticula are relatively common, there has not been a reported case, to our knowledge, of foreign bodies impacted within a Meckel's diverticulum. We report herein a case of a 2-year-old child who had two pennies trapped in a Meckel's diverticulum. This case demonstrates that foreign objects in the right lower quadrant that do not progress may be impacted in a Meckel's diverticulum.

Diagnosis and treatment of splenic fungal abscesses in the immune-suppressed patient.

In an 18-month period candidal splenic abscesses were diagnosed and treated in eight patients. Predisposing factors consisted of recent exposure to cytotoxic chemotherapy, long-term use of prednisone, neutropenia, antibiotic therapy for greater than three weeks, and gastrointestinal tract colonization with Candida. The patients had a clinical profile of nontoxic appearance with a temperature of more than 38.5 degrees C that was unresponsive to antibiotics, pain and tenderness over the upper abdominal quadrants, focal defects visualized on ultrasound and/or computed tomographic scans, and an elevated alkaline phosphatase level. Candida infection was confirmed by histologic examination of the liver and/or spleen in all patients. Diagnosis was made by percutaneous biopsy in one patient and exploratory laparotomy in seven. Five patients had splenectomy and antifungal drugs. In three patients the fungal abscesses resolved with amphotericin B therapy alone. Seven of eight patients were cured of their splenic abscesses, and five of eight were long-term survivors.

Delayed primary repair of esophageal atresia with tracheoesophageal fistula: is it worth the wait?

OBJECTIVE: To characterize a successful approach to the management of infants with long-gap esophageal atresia (EA) with tracheoesophageal fistula (TEF), significant prematurity with respiratory distress syndrome (RDS), or both, so as to preserve the native esophagus. DESIGN: A review of the medical records and office charts of a cohort of patients with EA and TEF. SETTING: A tertiary care children's hospital affiliated with a major university. PATIENTS: A total of 118 children with EA and TEF admitted from February 1986 through December 1996. All of the patients diagnosed as having EA and TEF during this period were included. INTERVENTION: Of the 118 infants, 88 received primary repair of EA and TEF within 48 hours of birth. An additional 23 children had the TEF divided and a gastrostomy placed secondary to (1) severe RDS and prematurity (n = 6), (2) long-gap EA (gap length > 4 cm or the upper pouch above the thoracic inlet (n = 10), or (3) associated cardiac defects (n = 7). Delayed primary EA repair was done when the RDS resolved or the gap length was 2 cm or less. MAIN OUTCOME MEASURES: Successful anastomosis of native esophagus. Comparison of incidence of gastroesophageal reflux, anastomotic complications, or survival between groups undergoing primary or delayed repair. RESULTS: Primary EA was accomplished in 88 patients. Delayed EA was successfully accomplished in 18 of the 19 surviving patients within 5 months, thereby preserving the native esophagus in all surviving infants. There was no difference in anastomotic complications, gastroesophageal reflux, or survival when the delayed group was compared with those who had a primary repair. CONCLUSIONS: Using delayed EA repair, all children with EA and TEF, regardless of gap length, can have their esophagus preserved. The primary cause of mortality was the association of a severe cardiac anomaly with EA and TEF.

Denaturation behaviour of DNA-protein-complexes detected in situ in metaphase chromosomes in suspension by Hoechst 33258 fluorescence.

The denaturation behaviour of DNA-protein complexes in metaphase chromosomes in suspension was analysed in situ by Hoechst 33258 fluorescence. The results indicate that due to the stability of the dye molecule and the product of the molecular extinction coefficient and the quantum yield at different temperatures, Hoechst 33258 is a suitable probe for the detection of double-stranded DNA. Thus, it is possible to monitor the concentration of double-stranded DNA in a suspension by measuring the total fluorescence intensity. The fluorescence denaturation profiles of DNA (calf thymus) were found to be comparable to absorption measurements. The decrease in fluorescence of metaphase chromosomes in suspension with increasing temperature may therefore be used to detect conformational changes of DNA in situ.

Surgical management of life-threatening and disfiguring sequelae of fulminant meningococcemia.

In recent years, because of prompt diagnosis and effective, aggressive resuscitation, the majority of infants and children with fulminant meningococcemia are surviving. From 1974 through 1984, 135 patients with this diagnosis were treated, and 126 of them survived. Although a purpuric skin rash developed in almost all of these patients initially, in eight of them it progressed to multiple confluent areas of cutaneous gangrene, usually associated with extensive necrosis of underlying subcutaneous fat, fascia, skeletal muscle, and even bone. Tissue necrosis seemed to be most extensive in regions of reduced blood flow, such as the extremities, but it almost never followed a pattern of anatomic vascular distribution. A most significant microscopic finding was the presence of multiple fibrin thrombi in vessels, often in close proximity with the foci of tissue necrosis. Five children who ranged in age from 6 months to 12 years required operation. Initially, all surface wounds were treated like full-thickness burns with silver sulfadiazene (Silvadene) dressings. Once the patient's condition had stabilized and the extent of tissue necrosis was apparent, all necrotic tissue was excised and the resulting wounds were temporarily covered with biologic dressings to assure a clean, viable base for skin grafting. Because the resulting quality of life postoperatively in all five surviving patients has been satisfactory, we recommend an aggressive surgical approach in patients with fulminating meningococcemia, despite what may initially appear to be devastating and even lethal complications of this disease.

Surgical management of multiple intestinal atresias.

The unusual problem of multiple intestinal atresias associated with jejunal atresia has been reviewed and seven cases have been summarized. Maintaining maximal bowel length without jeopardizing the patient is of utmost importance. The shish kebob technique has been illustrated in a patient with 15 obstructions. The other cases include one patient with the apple peel deformity and two with atresias associated with gastroschisis. Although these children are small in general, they are bright and otherwise healthy. The 90 percent mortality reported previously has been reversed by a combination of techniques and lessons learned from the leaders in pediatric surgery.

Hemodilution anesthesia: a valuable aid to major cancer surgery in children.

Since 1974, 25 children had 27 major cancer operations with the aid of hemodilution anesthesia. This includes operations for Wilms' tumors, liver tumors, adrenal tumors, pancreatic tumors, ovarian tumors, and resection of metastatic thoracoabdominal tumors. With the use of this method, operative blood loss has been greatly reduced and operative technique improved. At the beginning of surgery, whole blood is removed from the patient and replaced with three times the volume of a balanced electrolyte solution to maintain intravascular volume. After the time of significant blood loss has ceased, the patient's own blood is returned and diuresis stimulated with furosimide to remove the infused electrolyte solution. Hypothermia, allowing the temperature to drift down to just below 32 degrees C, helps protect vital organs against hypoxia and arterial hypotension to a mean of 50 torr systolic pressure is well tolerated and further reduces blood loss. Adequate tissue oxygenation can be maintained safely during hemodilution to a hematocrit value of 14 percent. Use of bank blood transfusion was necessary in only 6 of 25 patients. It was given when the calculated postoperative hematocrit value would be less than 30 percent. The diluted blood lost during surgery has a low red blood cell volume per milliliter and each milliliter lost depletes the total red blood cell volume by a lesser amount. Also, the ease and speed of surgery may be facilitated by the nearly bloodless operative field. Provided respiratory support is maintained, these children showed only minor clinical effects from this large fluid infusion. The majority of patients who are Jehovah's Witnesses accept this technique with the modification that we keep the blood moving and in direct contact with the patient's vascular system. Carefully planned and meticulously applied short-term hemodilution anesthesia provides a safe method for minimizing operative blood loss and reduces the difficulty of major cancer surgery in children.

Necrotizing enterocolitis in term neonates.

Necrotizing enterocolitis (NEC) is usually a disease of premature infants, but occasionally it affects the term neonate. A 5-year review of NEC at Children's Hospital and Medical Center identified the unique features of this disease in the term neonate. Eighty-one patients with NEC were treated between January 1984 and May 1989. Ten full-term neonates with gestational age greater than 38 weeks were identified for study. Charts were reviewed for recognized risk factors, clinical course, surgical intervention, and outcome. Ninety percent had a birth weight greater than or equal to 2.7 kg, and all were above 2.1 kg. NEC developed early in this group, with onset of disease in the first 48 hours of life in 50% of the group and within the first 4 days of life in 90%. The recognized risk factors of asphyxia, hypoglycemia, polycythemia, and respiratory distress were absent in 60%. Seven of 10 patients required exploratory laparotomy, whereas 3 of 10 required only medical treatment. Indications for operation were perforation in three patients, peritonitis in three patients, and mass in one patient. All patients requiring operations had severe colonic disease, with perforation of the colon in five of seven and full-thickness necrosis without perforation in two of seven. Two patients required total abdominal colectomy. Only one patient with perforated meconium ileus and associated NEC had small bowel involvement. This patient was the only mortality of the group. Subsequent intestinal continuity was restored in all surviving patients with no late complications. Two patients required resection of additional NEC strictures prior to reanastomosis. Of the three medically treated patients, none required subsequent operation for colonic stricture. Our experience indicates that the presentation, clinical course, and operative findings in full-term neonates with NEC differ from those encountered in the premature infant with NEC.

Early recognition of neonatal abdominal wall necrotizing fasciitis.

Necrotizing fasciitis (NF) of the abdominal wall occurring in newborns is associated with a 50% mortality rate. Improved survival requires early diagnosis followed by aggressive surgical débridement. During a 10-year period, we treated 7 infants who developed NF. During the same period, 32 infants were admitted with omphalitis that did not progress to NF. The patients with omphalitis and those with NF were compared. Tachycardia, abnormal white blood cell counts, induration, and violaceous skin discoloration were seen exclusively in the NF patients. Polymicrobial infections were documented in 28% of the omphalitis patients and 86% of the NF patients. All omphalitis patients survived, whereas 5 of 7 (71%) NF patients died. Adjuvant hyperbaric oxygen therapy was used for 4 infants with NF, 2 of whom survived (50%). NF is a highly morbid disease, that can be distinguished from other infant abdominal wall infections by the skin changes, white blood cell counts, heart rate, and microbiologic results. Prompt diagnosis of NF improves survival when combined with aggressive surgical débridement.

Improved three-year disease-free survival in osteogenic sarcoma.

Of 41 consecutive patients with newly diagnosed osteogenic sarcoma admitted to the Children's Orthopedic Hospital and Medical Center in Seattle, Washington, between 1952 and 1977, 19 treated before 1973 did not receive adjunctive chemotherapy (histological group) whereas after 1972 22 have been so treated (chemotherapy group). Chemotherapy consisted primarily of high doses of methotrexate and adriamycin for 16 months after surgical treatment. Patients in the historical group have been observed for a minimum of nine years (six patients) or until death (13 patients). The 13 surviving patients in the chemotherapy group have been followed for a minimum of three years (median five years) and all 12 disease-free patients have been off therapy for between one and a half and five and a half years (median three years). Overall, the chemotherapy group has had a significant increase in both survival (p = 0.03) and disease-free survival (P = 0.02) compared to the historical group. In 35 patients with localised disease at diagnosis, the three-year disease-free survival and the three-year survival rates were 18 per cent and 41 per cent respectively in the historical group, and 67 per cent and 78 per cent (life table estimates) respectively in the chemotherapy group. With adjunctive chemotherapy only one of the seven patients developing pulmonary metastases did so later than nine months after diagnosis. The superior results in the chemotherapy group could not be accounted for by differences in age, sex, presence of metastases at diagnosis, histopathology, location of primary tumour, type of initial or subsequent surgical treatment, or the use of standard or computerised lung tomography. Although the use of historical controls in this study does not exclude other changes as contributing to the observed improvement in outcome, our data support the contention that adjunctive chemotherapy improves both the disease-free survival and the overall survival of patients with osteosarcoma and rarely delays the onset of recurrent or metastatic disease.