Exchange-bias and magnetic anisotropy fields in core-shell ferrite nanoparticles

Exchange bias properties of MnFe\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document}2O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_4$$\end{document}4@\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma$$\end{document}γ–Fe\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document}2O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_3$$\end{document}3 core–shell nanoparticles are investigated. The measured field and temperature dependencies of the magnetization point out a well-ordered ferrimagnetic core surrounded by a layer with spin glass-like arrangement. Quasi-static SQUID magnetization measurements are presented along with high-amplitude pulse ones and are cross-analyzed by comparison against ferromagnetic resonance experiments at 9 GHz. These measurements allow one to discern three types of magnetic anisotropies affecting the dynamics of the magnetic moment of the well-ordered ferrimagnetic NP’s core viz. the easy-axis (uniaxial) anisotropy, the unidirectional exchange-bias anisotropy and the rotatable anisotropy. The uniaxial anisotropy originates from the structural core–shell interface. The unidirectional exchange-bias anisotropy is associated with the spin-coupling at the ferrimagnetic/spin glass-like interface; it is observable only at low temperatures after a field-cooling process. The rotatable anisotropy is caused by partially-pinned spins at the core/shell interface; it manifests itself as an intrinsic field always parallel to the external applied magnetic field. The whole set of experimental results is interpreted in the framework of superparamagnetic theory, i.e., essentially taking into account the effect of thermal fluctuations on the magnetic moment of the particle core. In particular, it is found that the rotatable anisotropy of our system is of a uniaxial type.

Dichotomy between Attractive and Repulsive Tomonaga-Luttinger Liquids in Spin Ladders

We present a direct NMR method to determine whether the interactions in a Tomonaga-Luttinger liquid (TLL) state of a spin-1/2 Heisenberg antiferromagnetic ladder are attractive or repulsive. For the strong-leg spin ladder compound (C_{7}H_{10}N)_{2}CuBr_{4} we find that the isothermal magnetic field dependence of the NMR relaxation rate T_{1}^{-1}(H) displays a concave curve between the two critical fields bounding the TLL regime. This is in sharp contrast to the convex curve previously reported for a strong-rung ladder, (C_{5}H_{12}N)_{2}CuBr_{4}. We show that the concavity and the convexity of T_{1}^{-1}(H), which is a fingerprint of spin fluctuations, directly reflect the attractive and repulsive fermionic interactions in the TLL, respectively. The interaction sign is alternatively determined from an indirect method combining bulk magnetization and specific heat data.

Step-scan time-domain terahertz magneto-spectroscopy

We present a novel approach for terahertz time-domain spectroscopy of magneto-optic phenomena. The setup used in this work combines a tabletop pulsed magnet and a standard terahertz time-domain spectroscopy system. The approach is based on repetitive operation of the pulsed magnet and step-wise increment of the delay time of the time-domain spectroscopy system. The method is demonstrated by plotting the magneto-transmission spectra of linearly polarized THz pulses through the hole gas of a Ge sample and the electron gas of GaAs, InSb and InAs samples. Cyclotron resonance spectra are displayed in the frequency range from 200 GHz to 2 THz and for a magnetic field up to 6 T. The GaAs spectra are analyzed in more detail using simulations based on the Drude model.

Le lambeau antérolatéral de cuisse. Étude rétrospective

The anterolateral thigh flap is a cutaneous or fasciocutaneous perforator flap, extensively used in China, Japan, Taiwan (Demirkan et al., 2000; Kimata et al., 1997; Koshima et al., 1993; Luo et al., 1999) but infrequently in Europe, probably because of variations in origin and course of the cutaneous perforators rending its use apparently less reliable. This study is about 13 anterolateral thigh flaps performed between November 1, 1998, and December 30, 2002, on 13 patients, four women, nine men. Among these 13 flaps, 11 were free flaps, two were pedicled flaps. The surgical procedure was decided because of loss of soft tissue localised in: floor of the mouth (2 flaps), limb (9 flaps), inguinal-illiac region (2 flaps). The mean age of patients was 47.7 years (ext. 23 years and 69 years). The quality of the result was evaluated by the surgeon as good or very good, fair or bad. The function of the donor site was evaluated by questionnaire of the patient and physical examination of knee extension. Three free flaps were re-explored because of venous thrombosis, one of them necrosed. No functional impairment was found. The result was evaluated by the surgeon as good or very good in 11 cases, fair for one case, "bad" in the case were the flap was lost. The results of the reconstructive procedure using the anterolateral thigh flap are satisfying. This flap is reliable if the surgical technique is strictly applied.

[Anterolateral thigh free flap. Surgical technique]

The anterolateral thigh free flap is a cutaneous or fasciocutaneous flap vascularised by one or several perforating arteries arising from the descending branch of the lateral circonflex femoral artery. Venous drainage occurs via the perforators or a similar route to the deep femoral system or the femoral vein. This flap is commonly used in Asia (China, Japan) where for certain teams, it replaces the classical radial forearm flap or the rectus abdominis myocutaneous flap for the reconstruction of head and neck defects after tumor ablation. We briefly describe the anatomy and vascularization of this flap and present the harvesting technique as well as the properties of the flap.

Telomerase activity and clinical progression in chronic lymphoproliferative disorders of B-cell lineage

The activation of telomerase, which specifically occurs in neoplastic cells to avoid telomere attrition at each cell division, is a necessary event in tumorigenesis. The evidence that telomerase is also present in normal B cells at different levels according to their differentiation and activation state makes the study of telomerase activity in B cell tumors particularly interesting. This review summarizes data concerning telomerase activity in chronic lymphoproliferative disorders of B-cell lineage (B-CLD), making suggestions regarding B-cell development and B-cell tumor histogenesis. The role of telomerase activity as a potential prognostic marker, as well as a target of new antineoplastic strategies is discussed.

Human immunodeficiency virus type 1 modulates telomerase activity in peripheral blood lymphocytes

The effect of human immunodeficiency virus type 1 (HIV-1) on telomerase activity in peripheral blood lymphocytes (PBL) was examined. Telomerase is an enzyme that is involved in mechanisms that control cell life span and replicative potential. HIV-1 reduced telomerase activity in in vitro-infected PBL and impaired enzyme activation upon cell stimulation. Telomerase activity was significantly lower in PBL from 23 HIV-1-infected patients than in PBL from healthy donors and significantly increased during highly active antiretroviral therapy (HAART) in 10 patients who had both a virological and an immunological response and in 5 and 8 patients with a virological or an immunological response, respectively. Further analyses of fractionated cells revealed that telomerase activity increased mainly in CD4(+) lymphocytes. Overall, these findings demonstrate that HIV-1 infection down-modulates telomerase activity and suggest that both the HIV-1 decline and immunorestoration in response to HAART contribute to increased telomerase activity in CD4(+) lymphocytes.

[The facial artery-buccinator musculo-mucosal flap for reconstruction of the palate]

Since may 1999, 5 facial artery musculo-mucosal (FAMM) flaps have been used for mucosal reconstruction of the top of the mouth. The FAMM flap, first described by Pribaz in 1993 is a modification of the naso-labial cutaneous flap. The flap can be inferiorly based on the facial vessels (orthograde flow) or superiorly based (retrograde flow). It can easily reconstruct palate, alveolus and soft palate defects. The are of rotation has its pivot point inferiorly at the retromolar trigone, superiorly at the gingival labial sulcus. The FAMM flap has been used for 2 palatal fistula after facial blast injuries and 1 secondary cleft palate surgery. For the cleft palate surgery an Lefort 1 osteotomy with iliac crest graft was associated. All the flap but one survive with primary healing. One partial necrosis was noted but spontaneously healed secondarily. The FAMM flap is a reliable flap for mucosal reconstructions of the top of the mouth. The flap dissection is easy and the donor site morbidity is low.

Telomerase activity in chronic lymphoproliferative disorders of B-cell lineage

The progressive shortening of telomeres at each cell division is a key mechanism in controlling cell proliferative capacity. The activation of telomerase, a reverse transcriptase that extends telomere length, potentially leads to unlimited cell proliferation, and is believed to play a critical role in the neoplastic process. High levels of telomerase activity have been demonstrated in almost all solid tumours; however, little data is available concerning its expression in chronic B-cell neoplasms. By using a quantitative polymerase chain reaction-based method we quantified telomerase activity in normal B lymphocytes, and in various B-cell malignancies, including chronic lymphocytic leukaemia (CLL), mantle cell lymphoma (MCL) and hairy cell leukaemia (HCL). Compared to normal B cells, which expressed very low levels of telomerase activity, malignant cells from most of the patients showed a significant increase in telomerase activity, with highest values observed in HCL samples. Moreover, among the CLL and HCL cases, significantly higher levels of telomerase activity were found in patients with progressive disease at 1 year follow-up versus patients with stable disease. These data suggest that telomerase activity might correlate with disease progression.

Serratus anterior free fascial flap for dorsal hand coverage

Reconstruction of the dorsal surface of hand defects requires thin, pliable, well-vascularized tissue with a gliding surface for the extensor tendon course. Fasciocutaneous or fascial flaps are the two surgical options. Fascial flaps present the advantages of thinness and low donor site morbidity. The authors present 4 cases of serratus anterior free fascial flap (SAFFF) used to cover the dorsum of the hand. The SAFFF with skin graft has many advantages for a fascial flap: long, constant vascular pedicle; very thin, well-vascularized tissue; low donor site morbidity; and the possibility of simultaneous donor and recipient site dissection. Furthermore, it can be associated with other flaps of the subscapular system for complex reconstructions. Of the 4 observations described, 2 used associated flaps, 1 used the SAFFF with a latissimus dorsi flap, and 1 used a scapular bone flap with the SAFFF. One flap was lost due to an electrical lesion to the forearm vessels.

[Serratus anterior muscle flap: indications and sequelae. 26 cases and review of the literature]

The authors report their experience of the use of the serratus anterior flap. Between 1992 and 1997, this flap was used for 14 head and neck and 11 limb and 1 intra-thoracic reconstructions. Twelve patients were examined for functional evaluation of the donor site. When only 2 or 3 slips are raised donor site morbidity is limited to moderate winging of the scapula with no functional disorders. Because of its thinness, and the length and diameter of the vascular pedicle, the serratus anterior flap is our favourite option for small wounds of the distal limb or composite and large defects in association with flaps of the subscapular system.

[The principle of Colson's flap applied to facial reconstruction]

Reconstruction of facial skin defects after cancer surgery or trauma with conventional flaps can give a poor cosmetic result when a thick flap is used to replace thin skin. The thickness of the flap can be a disadvantage to replacing a thin skin. Defatting the flap can resolve these situations, using the principle of Colson's flap. This operative procedure is safe, and improves the cosmetic results. The authors report a series of 21 full-thickness skin defects located at the junction of two or three regional units. The defects were repaired with total or partial undermining flap (frontal, nasoiabial, cheek flaps). The viability of these reconstructions was perfect and the cosmetic results fairly esthetic in comparison with conventional flaps.

[Forum on tissue expansion. Breast reconstruction by expansion in a young woman with sequelae of thoracic amniotic disease. Apropos of a case]

Amniotic disease or congenital skin sulci disease is a clinical entity covering a broad spectrum of malformations, usually involving the limbs, skull and face. This malformation is exceptional in the thorax. The authors report the case of a 22 year old woman with sequelae of thoracic amniotic disease, consisting of unilateral mammary aplasia, atrophy of the pectoralis major and latissimus dorsi muscles and deformity of the homolateral thoracic skeleton. They describe the breast reconstruction performed by tissue expansion in this patient.

[Facial injuries caused by firearms. Practical approach in emergencies]

Firearm injuries to the face are often a disconcerting clinical problem for the non specialized surgeon. The aim of this article is to de-mystify this emergency situation, which is common in Maxillo-facial units, and requires rigorous management and respect of well established general surgical principles. The authors subsequently review the need for secondary repair by a maxillo-facial and plastic surgeon.