Insights into calcific aortic valve stenosis: a comprehensive overview of the disease and advancing treatment strategies.

Aortic valve stenosis is a disease characterized by thickening and narrowing of the aortic valve (AV), most commonly due to calcification, which leads to left ventricular outflow obstruction called calcific aortic valve disease (CAVD). CAVD presents as a progressive clinical syndrome with cardiorespiratory symptoms, often with rapid deterioration. The modern-day pathophysiology of CAVD involves a complex interplay of genetic factors, chronic inflammation, lipid deposition, and valve calcification, with early CAVD stages resembling atherosclerosis. Various imaging modalities have been used to evaluate CAVD, with a recent trend of using advanced imaging to measure numerous AV parameters, such as peak jet velocity. Significant improvements in mortality have been achieved with transcatheter AV repair, but numerous therapeutics and modalities are being researched to delay the progression of CAVD. This article aims to provide a comprehensive review of CAVD, explore recent developments, and provide insights into future treatments with various novel modalities.

Efficacy and outcomes of antiplatelet therapy versus oral anticoagulants in patients undergoing transcatheter aortic valve replacement: a systematic review and meta-analysis.

Background: Recent guidelines suggest that antiplatelet therapy (APT) is the standard of care in the absence of long-term oral anticoagulation (OAC) indications in patients post-transcatheter aortic valve replacement (TAVR). The superiority of one method over the other remains controversial. Materials and methods: Several databases, including MEDLINE, Google Scholar, and EMBASE, were electronically searched. The primary endpoint was the all-cause mortality (ACM) rate. Secondary endpoints included cardiovascular death, myocardial infarction (MI), stroke/TIA, haemorrhagic stroke, bleeding events, systemic embolism, and valve thrombosis in post-TAVR patients receiving APT and oral anticoagulants (OACs). Forest plots were generated using Review Manager version 5.4, with a p value less than 0.05 indicating statistical significance. Subgroup analysis was performed to explore potential sources of heterogeneity. Results: Twelve studies were selected. No significant differences were observed in APT and OAC group for ACM [risk ratio (RR): 0.67; 95% CI:0.45-1.01; P=0.05], cardiovascular death [RR:0.91; 95% CI:0.73-1.14; P=0.42], MI [RR:1.69; 95% CI:0.43-6.72; P=0.46], Stroke/TIA [RR:0.79; 95% CI:0.58-1.06; P=0.12], ischaemic stroke [RR:0.83; 95% CI:0.50-1.37; P=0.47], haemorrhagic stroke [RR:1.08; 95% CI: 0.23-5.15; P=0.92], major bleeding [RR:0.79; 95% CI:0.51-1.21; P=0.28], minor bleeding [RR:1.09; 95% CI: 0.80-1.47; P=0.58], life-threatening bleeding [RR:0.85; 95% CI:0.55-1.30; P=0.45], any bleeding [RR:0.98; 95% CI:0.83-1.15; P=0.78], and systemic embolism [RR:0.87; 95% CI:0.44-1.70; P=0.68]. The risk of valve thrombosis was higher in patients receiving APT than in those receiving OAC [RR:2.61; 95% CI:1.56-4.36; P =0.0002]. Conclusions: Although the risk of valve thrombosis increased in patients receiving APT, the risk of other endpoints was comparable between the two groups.

Management of pediatric blunt abdominal trauma with split liver or spleen injuries: a retrospective study.

BACKGROUND: Blunt abdominal trauma is a prevailing cause of pediatric morbidity and mortality. It constitutes the most frequent type of pediatric injuries. Contrast-enhanced sonography (CEUS) and contrast-enhanced computed tomography (CECT) are considered pivotal diagnostic modalities in hemodynamically stable patients. AIM: To report the experience in management of pediatric split liver and spleen injuries using CEUS and CECT. PATIENTS AND METHODS: This study included 246 children who sustained blunt abdominal trauma, and admitted and treated at three tertiary hospitals in the period of 5 years. Primary resuscitation was offered to all children based on the advanced trauma and life support (ATLS) protocol. A special algorithm for decision-making was followed. It incorporated the FAST, baseline ultrasound (US), CEUS, and CECT. Patients were treated according to the imaging findings and hemodynamic stability. RESULTS: All 246 children who sustained a blunt abdominal were studied. Patients' age was 10.5 ± 2.1. Road traffic accidents were the most common cause of trauma; 155 patients (63%). CECT showed the extent of injury in 153 patients' spleen (62%) and 78 patients' liver (32%), while the remaining 15 (6%) patients had both injuries. CEUS detected 142 (57.7%) spleen injury, and 67 (27.2%) liver injury. CONCLUSIONS: CEUS may be a useful diagnostic tool among hemodynamically stable children who sustained low-to-moderate energy isolated blunt abdominal trauma. It may be also helpful for further evaluation of uncertain CECT findings and follow-up of conservatively managed traumatic injuries.

Primary hydatid cyst of the kidney revealed by hydatiduria: A case report.

Hydatid disease is frequent in endemic regions especially in sheep farming areas. Kidneys are uncommonly affected (2%-4%). We report a case of right renal colic with hydatiduria revealing a primary renal hydatid cyst ruptured in the mid calyx proved by computed tomography scan and laboratory testing. A kidney sparing surgery was performed by excision of the protruding dome and suturing of the fistula without any postoperative complication. This case emphasizes on further studies to define a standard treatment modality for renal hydatidoses.

[Correlation between detrusor thickness, intravesical prostatic protrusion and maximum urinary flow in the monitoring of benign prostatic hyperplasia]. / Corrélation entre épaisseur du détrusor, index de protrusion prostatique et débit urinaire maximal dans le suivi de l'hypertrophie bénigne de la prostate.

INTRODUCTION: Detrusor thickness (DT) and intravesical prostatic protrusion (IPP) are closely related to bladder outlet obstruction. The aim of our study was to look for correlation between DT, IPP and maximum urinary flow (Qmax). METHODS: It is a prospective, observational study including men over fifty managed for benign prostatic hyperplasia. Low urinary tract symptoms were assessed with the International Prostatic Symptom Score (IPSS). Pelvic ultrasound was performed for all patients measuring prostatic volume, bladder volume, post- void residual, DT and IPP. Uroflowmetry was performed for all patients, Qmax was noted. Qmax equal or less than 15ml/s was considered pathologic. RESULTS: Sixty patients were included for our study. Strong negative correlation was noted between DT, IPP and Qmax (r=-0.59, r=-0.61 respectively). Patients with pathologic Qmax had higher DT and IPP than those with normal Qmax, the difference was significant (P<0.01). Threshold values predicting pathologic Qmax were 3mm for DT and 7mm for IPP. ROC analysis reveals for DT an AUC of 0.84 (95% CI 0.76-0.92) and for IPP an AUC of 0.88 (95% CI 0.80-0.97). CONCLUSION: Detrusor thickness and intravesical prostatic protrusion have strong negative correlation with Qmax. These parameters could be an alternative to Qmax measurement if uroflowmetry is unavailable. LEVEL OF EVIDENCE: Grade B.

Accuracy of shear wave elastography in characterization of thyroid nodules in children and adolescents.

BACKGROUND: Thyroid nodules are an important health problem in children and adolescents. They possess a higher risk of malignancy in comparison to adults. This fact forms a great dilemma for clinicians. The aim of this study was to evaluate the reliability of shear wave elastography (SWE) as a non-invasive technique in the characterization of thyroid nodules in children and adolescents. METHODS: This prospective study included 56 patients with thyroid nodules. All the patients underwent clinical assessment, laboratory investigations, ultrasound, and Doppler examination, followed by an SWE assessment. Statistical analysis was performed and the best cut-off value to differentiate benign from malignant nodules was determined using the ROC curve and AUC. RESULTS: Seventy-two nodules were detected in the examined patients (ages ranged from 11 to 19 years, with mean age of 14.89 ± 2.3 years). Fifty-eight nodules (80.6%) were benign, and fourteen nodules (19.4%) were malignant (histopathologically proved). Highly suspicious criteria for prediction of malignancy by ultrasound and Doppler were hypoechoic echopattern, internal or internal and peripheral vascularity, microcalcifications, taller-than-wide dimensions, irregular outlines, and absence of halo (p < 0.05). The diagnostic performance for their summation was 70.69% sensitivity, 82.8% specificity, 80.45% accuracy, a 63.79% positive predictive value (PPV), and 87.9% negative predictive values (NPV). Regarding SWE, our results showed that 42.2 kPa was the best cut-off value, with AUC = 0.921 to differentiate malignant from benign nodules; the diagnostic performance was 85.71% sensitivity, 94.83% specificity, 93.06% accuracy, 76.9% PPV, and 93.2% NPV. CONCLUSION: Shear wave elastography is a non-invasive technique that can assist in the diagnosis of malignant thyroid nodules among children and adolescents.

Nature and outcome of malignant goiter: a revisit.

INTRODUCTION: the aim of this retrospective study is to review patients with malignant goiter, as regards their nature, demographic characterization, clinical presentation and preoperative histopathological data. METHODS: the study focused on a period of 4 years from December 2015 to January 2019. Patients´ demographic data, clinical presentation, Intra-operative findings, Pre and postoperative histopathological staging and grading were all recorded. Postoperative follow up whether early or late were also included. RESULTS: a total of 100% (n = 65) patients underwent surgery. The female to male ratio was found to be 5:1 (48 females and 17 males). Solitary nodule was the main clinical presentation in 80% (n = 52) of cases while 20% (n = 13) were multinodular swellings. Papillary carcinoma was recorded in 80% (n = 52) of patients while in 15.4% (n =10) of patients were having follicular carcinoma. The remaining 4.6% (n = 3) suffered of lymphoma; no medullary or anaplastic tumors were reported. CONCLUSION: thyroid cancer is the most commonly encountered endocrinal malignancy at our institute. Fine Needle Aspiration Cytology (FNAC) showed a high percentage of reliability in diagnosing thyroid cancer among our series. It is recommended to adapt this technique in initial screening of goiter patients in our local setting.

Operative management of non-iatrogenic pediatric and adolescence peripheral arterial trauma: An experience from a resource challenged setting.

OBJECTIVES: To evaluates the management and outcome of non-iatrogenic pediatric and adolescence extremity arterial injuries in a resource-challenged setting. METHODS: A retrospective study of the surgical management for non-iatrogenic extremity arterial trauma in pediatric and adolescence during the period from January 2008 to December 2015. This study was performed in two different countries at tertiary referral university and teaching hospitals having a specialized emergency and trauma centers. A thorough study of each patient record was collected from these centers including, the original demographic data and their clinical presentations. Operative data of each patient was also reported. RESULTS: During the 8-year period of the study, 149 pediatric and adolescent extremity arterial trauma patients were treated. They were 93.3% male, and 6.7% female, respectively. The age ranged from 2 to 18 years with a mean of 10.25 ± 4.05 years. Lower extremity arterial trauma was recorded in 51%, while 49% were having upper extremity injuries. Primary repair with end-to-end vascular anastomosis was performed in 51.7%, while an interposition reversed saphenous vein graft was performed in 48.3%. The operative procedures were performed by an experienced vascular surgeon and well-trained pediatric surgeons and general surgeons. Pseudoaneurysms was recorded in 9% of cases. Fasciotomy was performed in 15% of cases. CONCLUSION: Treatment of pediatric and adolescent extremity arterial injuries with primary end-to-end vascular anastomoses or with the use of an interposition reversed saphenous vein graft is a reliable, feasible, and more cost-effectiveness technique with good results. Moreover, it should be adopted for all vascular trauma patients, whenever possible.

Laparoscopy as a Primary Investigatory Tool in Pediatric Abdominal Masses.

BACKGROUND: Management of abdominal masses still pose a major challenge for pediatrician and surgeons with many controversy as regards the best investigatory tools. AIM OF THE WORK: This study was designated to evaluate the role of diagnostic laparoscopy in investigating equivocal pediatric masses that had undergone other imaging modalities. PATIENTS AND METHODS: A combined prospective and retrospective multicenter study over a period of 12 years from January 2005 to December 2016 was undertaken. This study included all children aged from 3 months to 15 years. Those having a documented diagnosis through other imaging modalities such as sonographic and/or computed tomography (CT) guided biopsy were excluded. All patients underwent multiport diagnostic laparoscopy for biopsy of the mass. All specimens were histologically assessed basically using Hematoxylin and Eosin (H and E) staining; some specimens had been immunohistochemically studied. RESULTS: One hundred and thirty-two patients were recruited in the study. They were 69 males and 63 females with a male to female ratio of1.1:1. The age ranged from 3 months up to 15 years with the mean age of 2.7 ± 0.8 years. Out of the total studied group, 54 patients were diagnosed with neuroblastoma (40.9%), while 66 (50%) were having nephroblastoma. The remaining 12 (9.1%) were having non-Hodgkin's abdominal lymphoma. Not all patients showed any complication related to the procedure. The mean follow up period was 3.6 years. Most of the cases (n=121) despite having a different diagnosis, were clinically staged as grade I to grade II (91.7%). Neither intraoperative nor postoperative complications were recorded during this technique. The mean operative time was 72 mins ± 20 in the earliest group; yet, it has declined to be 32 ± 12 minutes in the latest group due to the advancement of the learning curve. CONCLUSION: Laparoscopy is accurate and safe for investigating pediatric solid abdominal masses. It should be used as the sole tool for biopsy of solid abdominal tumors in pediatrics.

Reliability of sonoelastography in predicting pediatric cervical lymph node malignancy.

PURPOSE: Controversy exists as regards the best non-invasive diagnostic tool for pediatric cervical lymphadenopathy. The current work aimed to evaluate the reliability, sensitivity, specificity, and accuracy of sonoelastography in diagnosing benign and/or malignant pediatric cervical lymphadenopathy. METHODS: Prospective study took place over a period of 4 years from January 2013 to December 2016. A total of 177 lymph nodes (LNs) in 128 children with an age ranging from 11 months to 12 years were recruited in this study. Patients were 77 males and 51 females with a ratio of 3:2. All patients underwent a thorough history taking and clinical examination of the neck focusing on the cervical lymph nodes. After that, a B-mode sonography, Color Doppler ultrasound, and Sonoelastography were performed. Elastographic patterns of 1-5 were evaluated, whereas patterns of 3-5 (firm to hard) were suspected to have a malignant nature. Sonographic-guided aspiration cytology took place in 107 lymph nodes and excisional biopsy in 102 lymph nodes, whereas 13 lymph nodes responded adequately to conservative treatment. They proved to be benign reactive hyperplasia. RESULTS: The majority of LNs (87%) were of the malignant type that showed an elastographic pattern of 3-5. The same patterns were observed in only 6 (3.4%) of the benign LNs. Sonoelastography showed a sensitivity of 85.9%, specificity of 100%, PPV of 100%, NPV of 75.96%, and overall accuracy of 90.23% in distinguishing benign from malignant lymph nodes. Using the B-Mode ultrasound, an abnormal hilum was seen in 75%. The accuracy of color Doppler US reached 82.7%. CONCLUSIONS: Sonoelastography may be superior to other US modalities in elucidating different cervical lymph node biopsy helping to distinguish benign from malignant lesions. This may replace the lymph node biopsies in the future. Moreover, its use in the follow-up of patients with cervical malignancies may reduce the number of future biopsies. Further studies with more patients may be needed for a better assessment of results.

Clinical outcome and toxicity evaluation of simultaneous integrated boost pelvic IMRT/VMAT at different dose levels combined with androgen deprivation therapy in prostate cancer patients.

BACKGROUND: The role of dose escalation in patients receiving long-term androgen deprivation therapy (ADT) is still a controversial issue. The aim of the current study was to evaluate whether dose escalation for ≥76-80 Gy had any advantage in terms of biochemical disease-free survival (BDFS), distant metastasis-free survival (DMFS), or overall survival outcomes over the dose levels from 70 to <76 Gy. PATIENTS AND METHODS: The study included a cohort of 24 patients classified with high- and intermediate-risk localized prostate cancer. All patients received ADT, starting at 4-6 months before radiation therapy and continued for a total period of 12-24 months in high-risk patients. The treatment plan was given in two phases. In the first phase, the nodal planning target volume (PTV) and the prostate PTV received 48.6 and 54 Gy, respectively, over 27 fractions. The treatment was applied through intensity-modulated radiation therapy or volumetric modulated arc therapy with a simultaneous integrated boost technique. RESULTS: More than half of the patients were in T3-T4 stage, 79.1% of the patients were in the high-risk category, and all patients received ADT. The rate of acute grade II gastrointestinal and genitourinary toxicities in all patients were 41.7% and 62.5%, respectively. The rate of freedom from grade II rectal toxicity at 2 years was 89% and 83% for patients treated with dose levels <76 and ≥76 Gy, respectively. The rate of BDFS at 2 years was 90% and 85% for doses <76 and ≥76 Gy, respectively. The DMFS at 2 years was 100% and 76% for dose levels <76 and ≥76 Gy, respectively. CONCLUSION: In the current study, there were no significant differences in the BDFS and DMFS between patients treated with a dose of <76 and ≥76 Gy, including elective pelvic lymph nodes irradiation combined with ADT.

Second-line panitumumab as a triweekly dose for patients with wild-type KRAS exon 2 metastatic colorectal cancer: a single-institution experience.

OBJECTIVE: Panitumumab administered as monotherapy in colorectal cancer (CRC) has shown response and disease stabilization rates of approximately 30%. The current study aimed to evaluate the progression-free survival (PFS) and overall survival (OS) of patients with metastatic colorectal cancer (mCRC) treated with panitumumab every 3 weeks as a second line treatment. METHODS: This study is a retrospective analysis of 18 patients, aged more than 18 years, with wild-type KRAS exon 2 mCRC treated with panitumumab as a second-line single agent after progression on first-line chemotherapy. RESULTS: The median number of courses received was 10 (range, 4-29), and the median duration of treatment was 30 weeks (range, 12-96 weeks). After a median follow-up period of 13 months, the median PFS was 6 months (range, 4.3-7.7 months) and the median OS was 11 months (range, 7.4-14.5 months). The median PFS was 4 months for patients with < grade 2 skin toxicity and 6 months (range, 4.5-7.5 months) for patients with ≥grade 2 skin rash (P=0.05). The median OS was 9 months (range, 6.4-11.5 months) and 14 months (range, 11.6-16.3 months) for the two groups of patients (P=0.002). CONCLUSIONS: Panitumumab given every 3 weeks is effective and well tolerated in patients with advanced CRC that progressed after standard chemotherapy.

Induction FOLFOX followed by preoperative hyperfractionated radiotherapy plus bolus 5-fluorouracil in locally advanced rectal carcinoma: single arm phase I-II study.

Induction chemotherapy has many benefits of in locally advanced rectal cancer (LARC); one of these is the better control of distant failure. Hyperfractionated radiotherapy (HFRT) is new approach still on evaluation in preoperative setting of rectal cancer. We aimed to evaluate the efficacy of induction FOLFOX followed by HFRT in LARC. From September 2011 to December 2013, 27 patients with LARC were enrolled in this prospective, phase I-II study. Induction FOLFOX bolus was given for two cycles followed by HFRT (1.5 Gy twice day for 30 fractions over 3 weeks for a total of 45 Gy). 5-fluorouracil (5-FU) bolus was administrated during first and last 3 days of radiotherapy. Surgical resection was performed in 4-5 weeks further and followed by adjuvant FOLFOX bolus regimen. Twenty-one (77.8 %) patients were males and 22. 2 % of patients were females, and the median age at diagnosis was 46 years. Low sited tumor was the most presenting site (55.6 %). Clinically positive lymph nodes were presented in 70.4 % of patients. Twenty patients (74.1 %) underwent sphincter sparing procedure. Pathological complete response (pCR) was achieved in seven patients (25.9 %). Tumor and nodal downstaging were recorded in (70.3 %) and (42.1 %) of patients, respectively. Acute and late toxicities were in acceptable range. Two-year disease-free survival was 70.2 %, and overall survival was 87.5 %. Induction FOLFOX followed by HFRT and concurrent 5-FU improves pCR in LARC, and this combination was feasible with acceptable toxicity. Further evaluations are mandatory for this new approach.

Initial Surgery in Tailoring Treatment for Children With Stage II and III Wilms' Tumor: An Experience From Resource Challenged Settings.

BACKGROUND: Although Wilms' tumor (WT) is ranked first among primary childhood's renal neoplasm, controversy still exists regarding the best approach for its management. The study aimed at evaluating the role of initial surgery in treatment of stage II and III pediatric WT as a part of the short administration schedule as in National Wilms' Tumor Study (NWTS)-4 and evaluating its effectiveness compared to the long administration schedule. METHODS: The study included 30 children who were primarily diagnosed as stage II and III WT. They were divided into two equal groups. Group I (n = 15) included those children who had undergone neoadjuvant chemotherapy followed by surgery and postoperative chemotherapy, while group II (n = 15) included those children who had undergone primary surgery as an initial management followed by chemotherapy. After a mean postoperative follow-up period of 14 ± 5 months, clinical and radiological evaluation was performed to all patients. RESULTS: In group I, 10 patients were preoperatively diagnosed as stage II and five patients as stage III while in group II, 11 patients were proved to be stage II and four patients were stage III. After a follow-up period, clinical and radiological evaluation using CT was performed to all patients. In patients with stage II, evidence of recurrence was noted in three patients of group I whereas no patient showed any evidence of recurrence in group II. In patients with stage III, rebound increase in size was seen in two patients in group I and only one patient in group II. CONCLUSIONS: Initial surgical intervention with appropriate adjuvant therapy has better outcomes than the neoadjuvant chemotherapy and delayed surgery for children primarily diagnosed as stage II and III WT. Moreover, it may act as a short administration schedule for the treatment as it is not less effective than the long administration schedule and can be administered at a substantially lower total treatment cost.

Examination under anesthesia for management of impalpable undescended testis: a traditional technique revisited.

BACKGROUND: Many new tools for management of impalpable testes have emerged during the last few years, yet, not many studies have compared them to the traditional ways of managing this problem. This work aims to reiterate the importance of the physical examination under general anesthesia prior to the surgical procedure in order to decide the best surgical approach for patients with impalpable undescended testis, especially in developing countries where expensive investigations are at premium. PATIENTS AND METHODS: The study included boys who were treated consecutively and recorded prospectively from 2000 to 2010. Examination under anesthesia (EUA) was performed during the study period. Those in whom the testes were palpable underwent the standard orchiopexy procedure. In those boys where EUA failed to detect the testes, laparoscopy or extended inguinal exploration was carried out, and the testes were treated accordingly. RESULTS: On initial clinical evaluation at the outpatient clinic, 545 boys were recorded to have impalpable testes. Undescended testis was unilateral in 529 boys and bilateral in 16 boys. However, on examination under anesthesia only 189 (34.7 %) were impalpable. Among boys in whom the testes were palpable after EUA, 38 had small-size testes, 18 had normal size, and the remaining 300 boys had a sac or cord-like structure. CONCLUSIONS: Meticulous EUA facilitates the accurate diagnosis and planning of the surgical approach to patients with an impalpable testis and should remain part of the surgeon's skill set. It is an inexpensive initial evaluation tool that may help in saving hospital resources, especially in developing countries.

Sodium terbium(III) polyphosphate.

Single crystals of the title compound, NaTb(PO(3))(4), were obtained by solid-state reaction. This compound belongs to type II of long-chain polyphosphates with the general formula A(I)B(III)(PO(3))(4). It is isotypic with the NaNd(PO(3))(4) and NaEr(PO(3))(4) homologues. The crystal structure is built up of infinite crenelated chains of corner-sharing PO(4) tetra-hedra with a repeating unit of four tetra-hedra. These chains, extending parallel to [100], are linked by isolated TbO(8) square anti-prisms, forming a three-dimensional framework. The Na(+) ions are located in channels running along [010] and are surrounded by six oxygen atoms in a distorted octa-hedral environment within a cut-off distance <2.9 Å.

KPr(PO(3))(4).

Single crystals of the title compound, potassium praseodymium(III) polyphosphate, were obtained by solid-state reaction. The monoclinic non-centrosymmetric structure is isotypic with all other KLn(PO(3))(4) analogues from Ln = La to Er, inclusive. The crystal structure of these long-chain polyphosphates is built up from infinite crenelated polyphosphate chains of corner-sharing PO(4) tetra-hedra with a repeating unit of four tetra-hedra. These chains, running along [100], are arranged in a pseudo-tetra-gonal rod packing and are further linked by isolated PrO(8) square anti-prisms [Pr-O = 2.3787 (9)-2.5091 (8) Å], forming a three-dimensional framework. The K(+) ions reside in channels parallel to [010] and exhibit a highly distorted coordination sphere by eight O atoms at distances ranging from 2.7908 (9) to 3.1924 (11) Å.

The type IV polymorph of KEu(PO(3))(4).

Single crystals of KEu(PO(3))(4), potassium europium(III) polyphosphate, were obtained by solid-state reactions. This monoclinic form is the second polymorph described for this composition and belongs to type IV of long-chain polyphosphates with general formula A(I)B(III)(PO(3))(4). It is isotypic with its KEr(PO(3))(4) and KDy(PO(3))(4) homologues. The crystal structure is built of infinite helical chains of corner-sharing PO(4) tetra-hedra with a repeating unit of eight tetra-hedra. These chains are further linked by isolated EuO(8) square anti-prisms, forming a three-dimensional framework. The K(+) ions are located in pseudo-hexa-gonal channels running along [01] and are surrounded by nine O atoms in a distorted environment.

beta-casein and symmetrical triblock copolymer (PEO-PPO-PEO and PPO-PEO-PPO) surface properties at the air-water interface.

A comparison of beta-casein and symmetrical triblock copolymer (PEO-PPO-PEO and PPO-PEO-PPO) adsorption layer properties at the air-water interface has been carried out by bubble tensiometry and ellipsometry. It has been verified that the equation of state parameters (pi approximately gamma(y)) obtained from surface pressure (pi) and ellipticity in Brewster conditions (rhoB), which is proportional to the surface concentration (gamma) data, are the same as those obtained from dilational modulus epsilon and pi data. These two consistent approaches give further support to the theoretical model of block copolymers which has been previously developed for protein adsorption at fluid interfaces. It is shown that the interfacial behavior of the copolymer adsorption layer changes strongly as a function of the length of the hydrophilic and hydrophobic block sequences. The theoretical model may be used for the interpretation of the adsorption properties of the synthetic copolymers only when the size of the blocks is large enough. In the case of block copolymers, the coil is in a self-avoiding walk conformation (y = 3) whatever the temperature, while in the case of beta-casein, the polypeptide chain is partly collapsed at room temperature due to thermolabile noncovalent bonds. At the end of the first semidilute regime, there is clear evidence for a crossover toward a second semidilute regime for synthetic copolymers as well as for beta-casein but it is presently only partially characterized.