Water drops dancing on ice: how sublimation leads to drop rebound.

Drop rebound is a spectacular event that appears after impact on hydrophobic or superhydrophobic surfaces but can also be induced through the so-called Leidenfrost effect. Here we demonstrate that drop rebound can also originate from another physical phenomenon, the solid substrate sublimation. Through drop impact experiments on a superhydrophobic surface, a hot plate, and solid carbon dioxide (commonly known as dry ice), we compare drop rebound based on three different physical mechanisms, which apparently share nothing in common (superhydrophobicity, evaporation, and sublimation), but lead to the same rebound phenomenon in an extremely wide temperature range, from 300 °C down to even below -79 °C. The formation and unprecedented visualization of an air vortex ring around an impacting drop are also reported.

Drop rebound after impact: the role of the receding contact angle.

Data from the literature suggest that the rebound of a drop from a surface can be achieved when the wettability is low, i.e., when contact angles, measured at the triple line (solid-liquid-air), are high. However, no clear criterion exists to predict when a drop will rebound from a surface and which is the key wetting parameter to govern drop rebound (e.g., the "equilibrium" contact angle, θeq, the advancing and the receding contact angles, θA and θR, respectively, the contact angle hysteresis, Δθ, or any combination of these parameters). To clarify the conditions for drop rebound, we conducted experimental tests on different dry solid surfaces with variable wettability, from hydrophobic to superhydrophobic surfaces, with advancing contact angles 108° < θA < 169° and receding contact angles 89° < θR < 161°. It was found that the receding contact angle is the key wetting parameter that influences drop rebound, along with surface hydrophobicity: for the investigated impact conditions (drop diameter 2.4 < D0 < 2.6 mm, impact speed 0.8 < V < 4.1 m/s, Weber number 25 < We < 585), rebound was observed only on surfaces with receding contact angles higher than 100°. Also, the drop rebound time decreased by increasing the receding contact angle. It was also shown that in general care must be taken when using statically defined wetting parameters (such as advancing and receding contact angles) to predict the dynamic behavior of a liquid on a solid surface because the dynamics of the phenomenon may affect surface wetting close to the impact point (e.g., as a result of the transition from the Cassie-Baxter to Wenzel state in the case of the so-called superhydrophobic surfaces) and thus affect the drop rebound.

Autism spectrum disorder and paediatric dentistry: A narrative overview of intervention strategy and introduction of an innovative technological intervention method.

AIM: When treating patients with Autism Spectrum Disorder (ASD) the doctor-patient relationship can be very challenging. The dentist is often forced to work under general anaesthesia or conscious sedation. Children with ASD are patients with an increased risk of caries due to poor oral hygiene, a cariogenic diet and the use of xerostomal drugs. In this work therapeutic strategies used to treat this kind of patients are evaluated and a new method to treat children with ASD is presented in order to increase awareness about this condition in the dental field. METHODS: The Atlas Center (a non-profit organisation in Peurgia, Italy) has developed a software, called paINTeraction, that allows these special children to immerse themselves in a virtual reality with the help of an operator. Through this system the child can explore the dental office (and all its sounds and noises) before the real dental visit, thus connecting to the dental professional, achieving greater compliance and reducing anxiety. CONCLUSION: paINTeraction, with the use of digital technology tools, may be particularly well suited to introduce patients to the therapeutic environment, particularly in the dental setting.

Isolated brain metastasis of malignant choroidal melanoma 27 years after enucleation.

Choroidal melanoma primarily metastasizes to the liver. Isolated extrahepatic metastases have rarely been reported and they generally resulted in death within 6 months. We describe a patient who developed an isolated brain metastasis 27 years after his left eye was enucleated for choroidal melanoma. The metastasis was successfully treated with surgery and radiotherapy. The patient is alive and disease free 3 years after treatment of the metastasis. Posterior location and other clinical and morphologic characteristics of primary choroidal melanoma could explain the unusually long latency of this solitary extrahepatic metastatic disease. Lifelong surveillance to detect early signs of metastasis is mandatory for any patient treated for choroidal melanoma.

Influence of sex, age, and smoking habits on the urinary excretion of D-glucaric acid.

Reference values for urinary D-glucaric acid and the influence of sex, age and smoking habits were evaluated with a low-pH enzymatic method. D-Glucaric acid measured on spot urine samples from 573 healthy subjects gave mean concentrations (mumol/1) and D-glucaric acid/creatinine ratios (mmol/mol creatinine) of 56.1 (+/- 22.9) and 3.05 (+/- 0.99) for males and 53.3 (+/- 20.9) and 3.35 (+/- 0.95) for females. No difference between morning and evening was observed for urinary D-glucaric acid/1 values, but D-glucaric acid/creatinine was higher in the evening samples for both sexes. There was a negative correlation between D-glucaric acid/1 values and age in males but not in females: the decrease of D-glucaric acid concentration was, however, quantitatively very small. Smoking produced a significant increase in D-glucaric acid concentration and in the D-glucaric acid/creatinine ratio for males and also partially for females.

Low-pH method for the enzymatic assay of D-glucaric acid in urine.

The enzymatic methods for measuring D-glucaric acid in urine are based on the conversion of D-glucaric acid into its 1,4-lactone and measurement of inhibition of 1,4-lactone against beta-glucuronidase at pH 5.0. All the enzymatic methods described suffer from the disadvantage of a procedure that is complicated and inherently inaccurate, because the nature of glucaric acid/1,4-lactone equilibrium has not been properly considered in the development of such methods. After elucidating the factors influencing glucaric acid/1,4 lactone equilibrium in more detail, a low-pH enzymatic method has been developed in which the 1,4-lactone is formed in the urine sample by acid boiling at pH 3.8 and assayed at the same pH using beta-glucuronidase from Limpets. This procedure allows the acid/lactone equilibrium to remain stable during both the lactonization step and the enzymatic assay. The coefficient of variation for the proposed method (within-run and between-day precision) was from 4.2 to 8.7. The analytical recovery varied from 92-108%.

Biochemical and morphological observations on rat liver and kidneys six months after intravenous injection of a perfluorocompound emulsion.

The histological appearance of liver and kidneys and the energy metabolism of isolated liver and kidney mitochondria were evaluated in rats 6 months after intravenous administration of 1 ml of a perfluorocompound emulsion. Both liver and kidney specimens showed neither significant histological alteration nor the presence of intracytoplasmic perfluorocompound particles. A substantial depression of the rate of ATP synthesis was observed both in liver and kidney isolated mitochondria (with respect to control mitochondria) although the magnitude of the transmembrane electrical potential was unaltered. The depression of ATP synthesis in mitochondria isolated from perfluorocompound-treated rats appeared then unrelated to the presence of perfluorocompound micelles within the cells, and might result from the interaction of either the perfluorocompound or the emulsifying agent with the mitochondrial ATP synthetase.

Scanning electron microscope study of scalers.

Scanning electron microscopy was used to examine factory-sharpened, dulled, and resharpened scalers. The following observations were made: 1. The factory sharpened scalers exhibited metallic extensions from the lateral surface (wire edges). 2. The machine-resharpened instruments resulted in nonfunctional wire edges from the facial surface. Honing produced an exact meeting of facial and lateral surfaces. 3. Hand sharpening, using an Arkansas stone (grit 500) against the lateral surface away from the cutting edge, effected an exact meeting of the facial and lateral surfaces and no evidence of wire edges. 4. From this study an optimum cutting edge for a scaler is characterized as having a smooth, contiguous meeting of the facial and lateral surfaces free of wire edges. If a wire edge is present, it should be functional.

Cardiac surgery in patients over the age of 80 years.

The risk-benefit relationship of open heart surgery in octogenarians is not well established. Eighty consecutive patients over the age of 80 who underwent cardiac operations under cardiopulmonary bypass were evaluated. Twenty-five patients were in functional class IV, 42 in class III, and 13 in class II. Forty-four patients had only coronary artery bypass grafts (CABG), 12 only aortic valve replacement (AVR), 6 only mitral valve replacement (MVR), 12 CABG and AVR, 4 CABG and MVR, 1 CABG and aneurysmectomy, and 1 had resection of left atrial myxoma. Operative mortality (within 30 days) was 12.5% for the group. Mortality was related to bleeding, left ventricular failure, primary ventricular fibrillation, pulmonary failure, and renal failure. Mortality was higher in patients with (1) advanced functional class, (2) mitral valve replacement, (3) postoperative hemorrhage, and (4) associated pulmonary disease. While a generally conservative approach is recommended for octogenarian patients, many with life-threatening cardiac disease, especially those free of major multisystem illnesses, should not be denied the benefit of surgical treatment.

Sinus node suppression in acute strokes--case reports.

The authors report on 5 patients, 4 of them observed over a period of only two months in one community hospital, who developed profound sinus node suppression in the early phase following acute strokes. This complication resulted in the death of 2; in the remaining 3, it was controlled by electrical cardiac pacing or intravenous atropine. In 3 patients, the strokes were due to subarachnoid hemorrhage, and in 2, they were secondary to vascular occlusion. In at least 4 patients, the prognosis seemed favorable from a neurologic standpoint. Vagally mediated sinus node arrest may, therefore, represent a potentially fatal complication of strokes and may be more frequent than currently appreciated. Continuous monitoring in the early phase of acute strokes and pacemaker therapy may be lifesaving in some patients. This and the general phenomenon of functional failure of the sinus node due to a variety of causes are discussed.

Porocarcinoma detected by fine needle aspiration biopsy of a node metastasis. A case report.

BACKGROUND: Porocarcinomas were first reported by Pinkus and Meherengan in 1963 as uncommon malignant adnexal tumors of the skin characterized by epidermotropism with pagetoid diffusion within the epidermis. CASE: The cytologic findings of an eccrine porocarcinoma lymph node metastasis in a 65-year-old female and histologic features of the skin recurrence are reported. Metastasis was firstly identified by fine needle aspiration biopsy (FNAB) performed on one inguinal lymph node. Cytologically the tumor was characterized by atypical malignant cells showing clear granular or keratinized cytoplasm and vesicular nuclei, with prominent nucleoli, which were irregularly dispersed or forming nests or cords, sometimes harboring central necrosis. The skin metastasis, detected after the cytologic FNAB diagnosis, showed superficial dissemination within the epidermis and dermal invasion. CONCLUSION: Cytologic diagnosis of porocarcinoma metastases by FNAB is important for adequate treatment, but adherence to strict diagnostic criteria is necessary. The tumor cells could be histogenetically related to the intraepidermal duct cells of the eccrine sweat glands, and pagetoid diffusion is considered a sort of homing phenomenon.

Fabrication of a teaching aid for dental soft tissue management and suturing.

A technique for fabrication of a model to aid in teaching surgical management and suturing is presented. The model, which simulates dentition, supporting periodontium, and gingival soft tissue, can be made inexpensively in a dental laboratory.

[Up-date on acute ischemia of the limbs]. / Aggiornamenti in tema di ischemia acuta degli arti.

The authors report their experience in the treatment of acute ischemia of the limbs during the last year. They underline the importance of a right diagnostic and therapeutic treatment particularly in a little hospital, as reported in an algorytm published recently in the literature. They analyze 11 patients, one of them with an embolism of the arm, with a different degree of ischemia. The results are similar to those reported in the literature.

[Acute intestinal ischemia. Review of the literature and personal experience]. / Ischemia intestinale acuta. Revisione della letteratura ed esperienza personale.

The authors report the experience of their surgical department in the diagnosis and treatment of acute arterial mesenteric ischaemia. Their results are similar to those of the literature. Stress is laid on early diagnosis and interest of mesenteric angiography, laparoscopy and color flow ultrasound. Arterial revascularisation must be the surgical aim but the prognosis of acute mesenteric ischaemia remains very severe.

Effect of plasma exchange in a patient with prolonged deep coma from thrombotic thrombocytopenic purpura.

The clinical, laboratory and instrumental data of a patient with thrombotic thrombocytopenic purpura (TTP) are reported in detail, with reference to an articulated therapeutic regimen including plasma exchange, high-dose methylprednisolone and dipiridamole. Particular emphasis is placed on the dramatic improvement obtained with this treatment despite a very delayed diagnosis and prolonged, severe neurological involvement. A short discussion and review of the literature concerning the role of plasma-exchange in the treatment of TTP is reported.

Ovarian teratomas. An analysis of 134 cases.

All ovarian teratomas observed from 1979 to 1989 in the Institute of Pathology University of Padua are revised. Mature and immature teratomas are analyzed separately because of their different prognoses.

[Postoperative pneumonia caused by Candida in 500 lung surgery patients]. / Le polmoniti da Candida in 500 interventi di resezione polmonare.

BACKGROUND: Postoperative infections continue to be one of the most frequent complications in hospitalized patients. The incidence of fungal infection has been steadily rising. While Candida albicans remains the most common yeast species isolated in hospitalized patients, other Candida species have been increasingly isolated. METHODS: From 1996 to 2001, a prospective study of 500 consecutive lung surgery patients treated by the same surgical team was conducted to monitor the number of postoperative infections and to evaluate the epidemiology of bacterial and fungal infections. RESULTS: At least one postoperative infection developed in 18% of patients. Of the 51 patients who developed postoperative pneumonia, 24 underwent microbiological examination of sputum. In 19 of them, the culture yielded isolates of one or more Candida species. Slightly under half of patients (47%) with cultures positive for mycetes received treatment with fluconazole until the clinical infection resolved. The drug was well tolerated by all treated patients. CONCLUSIONS: The incidence of fungal infection has increased also at our center. In 19 of 24 patients with postoperative pneumonia, sputum cultures yielded Candida species isolates. Many factors may be contributing to the rise in fungal infections after surgery. As pneumonia caused by Candida led to a significantly longer length of hospital stay in our case series, we draw attention to the importance of early diagnosis of postoperative mycotic lung disease in order to institute timely and targeted therapy.

[Acute cholecystitis]. / La colecistite acuta.

A review of 360 patients surgically treated for biliary conditions revealed 54 cases of acute cholecystitis. After a report on the aetiopathogenesis, epidemiology, pathological anatomy and clinical aspects of the condition, early surgical treatment as soon as the diagnosis has been confirmed by tests, is recommended.

[Hypoplasia of intra- and extrahepatic bile ducts associated with congenital abnormalities]. / Ipoplasia delle vie biliari intra ed extraepatiche con malformazioni congenite associate.

The present report deals with a patient affected by Alagille's syndrome. The clinical hallmark of this syndrome is chronic cholestasis with ductular and extrahepatic hypoplasia and associated multiple congenital malformations. The diagnosis was made by hepatobiliary scanning with TC99-HIDA, transendoscopic cholangiography and liver biopsy.

Unraveling wetting transition through surface textures with X-rays: liquid meniscus penetration phenomena.

In this report we show that synchrotron X-ray radiography is a powerful method to study liquid-air interface penetration through opaque microtextured surface roughness, leading to wetting transition. We investigate this wetting phenomenon in the context of sessile drop evaporation, and establish that liquid interface sinking into the surface texture is indeed dictated by the balance of capillary and Laplace pressures, where the intrinsically three-dimensional nature of the meniscus must be accounted for. Air bubble entrapment in the texture underneath impacting water drops is also visualized and the mechanisms of post-impact drop evaporation are discussed.