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1.
Phys Chem Chem Phys ; 18(14): 9758-69, 2016 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-27003320

RESUMO

The properties of nanomaterials are highly dependent on their size, morphology, crystal phase, etc., which in turn depend on the method of synthesis. We report here the electrical and magnetic characterisation of sonochemically synthesized Fe(3+) doped nano BaTiO3 samples. The dopant ion concentration has been optimized and the coexistence of ferromagnetism and ferroelectricity has been observed in the sample. With increase in Fe(3+) doping from 0 to 20 mol%, a gradual phase change from tetragonal to hexagonal occurred in these sonochemically synthesized BaTiO3 nanomaterials. Below 15 mol% Fe concentration the material displays ferroelectric behaviour with the absence of any magnetic ordering, while at an Fe concentration of ∼15 mol% the material exhibits both room temperature ferromagnetism and ferroelectricity. Ferromagnetism as well as relaxor type behaviour has been observed in the BaTiO3:Fe(3+)(20%) sample. We have studied the ferromagnetic and ferroelectric ordering in these sonochemically synthesized Fe(3+) doped BaTiO3 nanomaterials and have tried to correlate the results with their crystal structure and morphology. The origin of ferromagnetism in these materials has been attributed to both intrinsic as well as extrinsic factors.

2.
J Nanosci Nanotechnol ; 16(3): 2453-63, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27455655

RESUMO

In view of potential biomedical application of the noble metal nanoparticles, we report a size controlled yet simple and green synthesis of resveratrol stabilized silver and gold nanoparticles having low polydispersity of size. Here, resveratrol plays two simultaneous roles, reducing the metal ions and providing efficient capping of the small nanoparticles. This gives rise to specific size of silver and gold nanoparticles at specific ratios of metal to resveratrol. The particles have been characterized by XRD and transmission electron microscopy. The nanoparticle sols are stable for months. The UV Visible absorption spectra of the silver sol show the plasmon peak of spherical nanoparticles, presence of which is further reflected in the TEM images. Size of the silver particles obtained is in between 11 to 21 nm depending on the ratio of resveratrol to metal ion used. Resveratrol capped silver nanoparticles exhibit high antibacterial activity against Gram negative wild type E coli BW (25113). The minimum inhibitory concentration (MIC) of nano-silver against the bacterium has been estimated to be 6.48 µg/ml, which is significantly lower than that reported in some earlier as well as recent publications. Reaction of gold ions with resveratrol, on the other hand, produces gold nanoparticles of sizes varying from 7 to 29 nm at different ratios of resveratrol to the metal ions. Particles with higher size and aspect ratio are formed at lower concentration of the capping agent whereas particles with very small size and pseudo-spherical morphology are formed at higher capping concentration. Difference in the formation kinetics of silver and gold nanoparticles has been attributed to the different growth mechanisms in the two cases. Possible modes of anchorage of resveratrol to silver nanoparticles have been investigated using surface enhanced resonance Raman spectroscopy (SERS) which shows that the silver nanoparticles are capped by resveratrol molecule primarily through O-Ag linkages of the p-OH aromatic ring. This, in turn, demonstrates the feasibility of using these nanoparticles as SERS templates.


Assuntos
Antibacterianos/farmacologia , Ouro/química , Nanopartículas Metálicas , Prata/química , Estilbenos/farmacologia , Escherichia coli/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Transmissão , Resveratrol , Espectrofotometria Ultravioleta , Análise Espectral Raman , Estilbenos/química , Difração de Raios X
3.
J Orthop Case Rep ; 14(6): 113-117, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38910988

RESUMO

Introduction: Giant cell tumors (GCT) are a relatively uncommon type of non-cancerous bone growth, representing around 4-10% of all bone tumors. These tumors tend to exhibit local aggressiveness and are typically prevalent in individuals between 20 and 40 years old. Commonly observed locations for GCT include the distal femur, proximal tibia, and the distal end of the radius. However, occurrences at the distal end of the ulna are rare, accounting for only 0.45-3.2% of cases. Case Report: In this instance, we present the case of a 36-year-old male diagnosed with a GCT specifically located in the left distal ulna. Our approach involved managing the patient through the complete removal (en-bloc resection) of the distal ulna. Following this, we performed an extensor carpi ulnaris (ECU) tenodesis to stabilize the proximal stump. After 2-year follow-up, the patient exhibited positive outcomes, displaying satisfactory wrist joint mobility and functionality without any signs of tumor recurrence. Conclusion: This case emphasizes the effectiveness of wide resection as a viable treatment for huge GCTs in the distal ulna. Utilizing tenodesis with the tendon of ECU significantly contributes to stabilizing the ulnar stump, leading to improved wrist function.

4.
Cureus ; 16(5): e60333, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38883054

RESUMO

Neglected shoulder dislocation is a relatively rare occurrence characterized by structural changes in bone and soft tissue. Surgical intervention is often necessary, yet no universally accepted treatment approach exists, presenting a challenging clinical scenario. A 45-year-old female presented with an eight-month-old neglected anterior shoulder dislocation, compounded by a Hill-Sachs lesion from a previous fall. Treatment comprised open reduction in conjunction with the Latarjet procedure. Regular follow-up evaluations were conducted over three years post-surgery, revealing satisfactory outcomes including good range of motion, bony union, and absence of dislocation episodes. Managing neglected shoulder dislocations, particularly those with significant bone defects, poses unique challenges involving soft tissue contracture, bone loss, and associated fractures. Despite these complexities, open reduction combined with the Latarjet procedure demonstrated a high success rate in preventing further shoulder dislocation, albeit with a persistent risk of shoulder joint osteoarthritis.

5.
Cureus ; 16(5): e59807, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38846186

RESUMO

Synovial chondromatosis is a rare condition characterized by benign metaplasia of the synovial membrane, leading to nodular growths within the joint space. We present the case of a 58-year-old woman with persistent pain and stiffness in her right elbow, ultimately diagnosed with synovial chondromatosis. Examination revealed joint effusion, tenderness, and restricted range of motion, with palpable loose bodies and ulnar nerve symptomatology. X-ray confirmed the diagnosis. Open synovectomy was performed, with meticulous attention to ulnar nerve protection and decompression. Postoperative care included analgesics, anti-inflammatories, and physiotherapy. Synovial chondromatosis of the elbow requires prompt diagnosis and surgical intervention to alleviate symptoms and prevent complications. Prognosis is favorable with complete removal of the affected tissue. Ulnar nerve palsy should be carefully addressed during surgical management.

6.
Cureus ; 16(5): e60294, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38872661

RESUMO

Myositis ossificans (MO) is a benign condition where bone forms within muscles due to increased activity of the periarticular tissues. Trauma is the most common cause. Nontraumatic MO is exceedingly rare. We present a rare instance of nontraumatic MO affecting the hip in a 32-year-old patient. The patient had a known case of seizure disorder and also had a history of a cerebrovascular accident (CVA). Despite the absence of trauma or known predisposing factors, the patient developed a sizable mass in the left hip, causing pain and restricted range of motion (ROM). Surgical excision of the mass was successful, resulting in complete removal and subsequent improvement in hip function and pain relief during postoperative recovery. Histopathological examination confirmed the diagnosis of MO. The patient's ROM normalized, and there were no signs of recurrence at the one-year follow-up. This case highlights the importance of recognizing MO in hip pain cases without trauma. Timely surgery through the approach described effectively removes the mass, preventing recurrence without compromising vital structures. It showcases a successful multidisciplinary approach for rare musculoskeletal conditions, offering valuable insights into similar cases.

7.
J Orthop Case Rep ; 14(3): 136-140, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38560311

RESUMO

Introduction: An aneurysmal bone cyst (ABC) is an unusual, non-cancerous bone lesion that is characterized by its lytic (causing bone loss), hemorrhagic, and expanding nature. ABCs are relatively rare, making up only 1% of all bone tumors. These cysts are typically found in long bones and the spine but are very rarely seen in the metatarsal bones, making such occurrences quite uncommon. Case Report: In this case report, we present a case of ABC of the 3rd metatarsal in a 26-year-old female with complaints of long-standing foot pain and gradually increasing swelling of the dorsum of the foot. After radiological evaluation, she had undergone histopathological evaluation. An en bloc resection of the metatarsal along with the tumor mass was performed and the gap was replaced with an ipsilateral fibular strut graft. Histopathological examination of the resected tissue was suggestive of ABC without any evidence of malignancy. At the end of 1 year of follow-up, she is now completely pain free with intact rom of foot and ankle. Conclusion: The present study aims to describe a case of ABC of the metatarsal, a condition that not only poses a diagnostic dilemma but also constitutes a challenge in the management of lesion.

8.
Cureus ; 16(4): e58455, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38765375

RESUMO

Cerclage wiring and tension band wiring are commonly utilized in orthopedic surgeries for patellar fractures, but wire breakage is a recognized complication. This report presents a rare case where a broken cerclage wire exhibited intraarticular intracapsular migration, prompting open removal adjacent to the medial femoral condyle after unsuccessful attempts at arthroscopic extraction. A 50-year-old male with a history of patellar fracture fixation using cerclage and tension band wiring, presented with persistent knee pain and restricted motion. Radiographs revealed a united patellar fracture with a broken cerclage wire, and 3D CT pinpointed the wire fragment in the posterior knee compartment. Arthroscopic removal attempts through standard portals were ineffective, leading to a subsequent open removal via a Burk and Schaffer approach. Intraoperative fluoroscopy guided the thorough dissection, exposing the broken wire deep within the joint capsule, proximal to the intercondylar notch and adjacent to the medial femoral condyle. Meticulous extraction mitigated potential risks of cartilage and neurovascular damage. Follow-up imaging confirmed successful wire removal, and the patient experienced satisfactory functional recovery without significant complications. This case highlights the rare occurrence of intraarticular intracapsular migration of a broken cerclage wire and underscores the importance of timely removal to mitigate risks of cartilage and neurovascular damage. While arthroscopic removal is generally successful, cases of failure may necessitate open extraction, particularly when the wire is located posteriorly. The described approach, assisted by intraoperative fluoroscopy, proved effective in safely removing the broken wire and ensuring optimal patient outcomes.

9.
BMJ Case Rep ; 17(5)2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38782442

RESUMO

The treatment of acute heel pad avulsion differs significantly from managing other soft tissue injuries due to its unique soft tissue structure. This case report outlines a scenario involving a male in his 20s who suffered heel pad avulsion without a calcaneal fracture but with an ipsilateral medial malleolus fracture after a twisting injury to the ankle caused by a road traffic accident. Immediate action was taken within 24 hours of the injury, involving thorough debridement of the wound, fixation to the calcaneum using multiple K-wires, primary suturing and internal fixation of the medial malleolus with two cannulated cancellous screws. Postoperative care included PRP (platelet-rich plasma) injections into the wound twice, removal of K-wires after 6 weeks and allowing walking with full weight bearing after 8 weeks. A year later, the wound had completely healed, and the patient was comfortably walking pain-free with full weight-bearing capabilities.


Assuntos
Fios Ortopédicos , Fixação Interna de Fraturas , Plasma Rico em Plaquetas , Humanos , Masculino , Fixação Interna de Fraturas/métodos , Calcanhar/lesões , Lesões dos Tecidos Moles/terapia , Desbridamento/métodos , Calcâneo/lesões , Adulto Jovem , Traumatismos do Pé/terapia , Traumatismos do Pé/cirurgia , Resultado do Tratamento
10.
J Orthop Case Rep ; 14(2): 160-164, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38420226

RESUMO

Introduction: The recent surge in joint replacement surgeries in India, particularly total knee and hip replacements, is notable. The majority of patients undergoing these procedures suffered from knee osteoarthritis or femoral head avascular necrosis. However, this increase in joint replacements has also led to a rise in periprosthetic joint infections (PJI), a severe and costly complication. PJI is responsible for 25% of total knee arthroplasty failures and 15% of total hip arthroplasty failures. Various risk factors, such as diabetes, fractures, and arthritis, are associated with PJI development. Bacterial infections, notably Staphylococcus species, are the primary cause of PJI, but rare fungal infections are often caused by Candida and Aspergillus. There is a lack of clinical trials and limited knowledge about the prevalence and treatment of fungal PJIs. Case Report: This report presents a unique case of delayed PJI caused by Candida albicans in an otherwise healthy patient. Conclusion: This case report emphasizes the need for further research and standardized treatment guidelines. Treatment typically involves a two-stage revision with extended antifungal therapy. The optimal duration of antifungal treatment remains uncertain.

11.
Cureus ; 16(5): e60239, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38872693

RESUMO

Background This study investigates the functional outcomes of single-bundle arthroscopic anterior cruciate ligament (ACL) reconstruction, comparing the use of two distinct graft sources: peroneus longus (PL) graft and hamstring graft. The choice of graft material in ACL reconstruction is crucial for optimal postoperative results, and this study aims to contribute valuable insights into the comparative efficacy of these two graft types. Method This open-label randomized comparative study involved a carefully selected cohort of patients undergoing single-bundle arthroscopic ACL reconstruction. Participants were randomly assigned to either the PL graft group or the hamstring graft group. Surgical procedures were conducted using standardized techniques, and postoperative rehabilitation protocols were closely monitored. Functional outcomes, including range of motion, stability, and patient-reported measures, were assessed at predefined intervals to ensure comprehensive data collection. Results The study underscores significant demographic and clinical factors in ACL reconstruction outcomes. Participants were predominantly aged 17-30 years (58.33%) with a mean age of 29.27 years and exhibited a male predominance (80.56%). Common complaints included knee pain and instability, primarily due to falls from bikes (55.56%) or sports-related trauma (44.44%). Notably, PL grafts demonstrated advantages over hamstring grafts, with longer mean length (10.11 mm vs. 8.77 mm, p=0.0001) and shorter operation times. Visual analog scale (VAS), International Knee Documentation Committee (IKDC), and Tegner Lysholm scores show no significant differences between grafts over the period of time. There is no notable foot eversion weakness or significant donor site morbidity after the PL graft harvest. Hamstring graft cases exhibit a higher incidence of altered sensation and muscle atrophy, suggesting the potential benefits of PL grafts for improved surgical outcomes. Conclusions Graft comparisons favored PL grafts due to longer length, and functional outcome assessments between the two graft types. However, foot and ankle strength assessments revealed fluctuations in strength recovery with PL grafts, highlighting the need for tailored rehabilitation. Thigh circumference variations suggested potential muscle atrophy in the hamstring graft group, along with reported paresthesia in the ipsilateral proximal leg. In conclusion, PL grafts offer potential advantages for ACL surgery, but ongoing monitoring and specialized rehabilitation are crucial.

12.
J Orthop Case Rep ; 14(6): 108-112, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38910997

RESUMO

Introduction: Osteoblastoma is an uncommon benign bone tumor characterized by the formation of osteoid tissue, occurring more frequently in men than in women. It is often associated with osteoid osteoma and can be found at various locations in the skeleton, although it is rare in the sacrum. Typically, these lesions involve the posterior elements of the spine, including the pedicle and the lamina. We would like to present a case of sacral osteoblastoma, clinically presenting as lumbar radiculopathy, which was treated at our institute. Case Report: A 23-year-old male presented to us with left gluteal pain radiating to the left lower limb pain for 2 years. He had multiple consultations elsewhere and was being treated as a probable case of a lumbar disc lesion with left lower limb radiculopathy. X-rays appeared normal. Magnetic resonance imaging of the lumbar spine and pelvis revealed a T2 hyperintense lesion affecting the posterior elements of S3, compressing the nerve roots. Computed tomography (CT) was a better investigation modality for osteoblastoma. En bloc excision and curettage were performed, and the histopathological analysis confirmed the diagnosis of osteoblastoma. The patient had immediate relief of symptoms postoperatively with no complications. At 2-year follow-up, the patient had no evidence of recurrence on a follow-up CT scan. Conclusion: Osteoblastomas predominantly occur in the spine, with rare instances in the sacrum. Treatment typically involves en bloc excision. Confusing clinical presentation may delay diagnosis, resulting in persistent morbidity.

13.
J Orthop Case Rep ; 14(3): 73-77, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38560317

RESUMO

Introduction: ?Introduction: Periosteal chondromas are rare, slow-growing, benign cartilaginous tumors arising from the cortical surface of the bone, beneath the periosteal membrane. Typically affect young males, the most common site being the proximal humerus. There have been no reported cases of periosteal chondroma of the talus in the literature. Case Report: A 9-year-old Indian boy presented with a 1.5-year history of atraumatic right ankle pain and swelling, exacerbated by walking, with limited dorsiflexion. Physical examination revealed a firm, painless swelling on the anterior ankle's talar region, accompanied by equinus deformity. Radiography displayed osseous masses on the anterior talus. Magnetic resonance imaging indicated well-defined osseous growths originating from the talus's anterior aspect, likely osteochondromas, with adjacent osseous fragments in the tibiotalar joint, suggestive of loose bodies, supporting a clinical diagnosis of synovial chondromatosis. Surgical excision revealed whitish, hard, irregular tissue, confirmed as periosteal chondroma on histopathology. After 6 months, the patient is pain-free with unrestricted movement and no clinical or radiological signs of recurrence. Conclusion: This case report presents a unique instance of previously unreported talus periosteal chondroma, adding novelty to medical literature. It details the diagnostic challenges and its intricacies. It provides a comprehensive overview of clinical presentation, imaging and histopathological findings, differentials and provisional diagnosis, surgical approach, and post-operative outcomes. The successful surgical management, along with the specific details of the surgical procedure (anteromedial approach, excision, and curettage), adds practical insights for orthopedic surgeons and contributes to the existing knowledge on treatment strategies for talus periosteal chondroma. This report will serve as an excellent educational resource.

14.
Cureus ; 16(3): e56772, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38650804

RESUMO

A 45-year-old woman complained of left wrist pain and swelling for two years accompanied by limited dorsiflexion. Plain X-rays revealed an abnormal bony mass in the carpal bones, further evaluated using computed tomography and magnetic resonance imaging. Upon confirmation of the benign nature surgical excisional biopsy of the lesion, the histopathology confirmed the diagnosis of Bizarre parosteal osteochondromatous proliferation (BPOP). The patient has remained pain-free and actively involved in her routine for the past two years. BPOP, affecting the carpal bones of the hand, are exceptionally rare occurrence. Attentive preoperative evaluation helps in diagnosis and to initiate measures to avoid recurrence.

15.
J Orthop Case Rep ; 14(4): 13-17, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38681929

RESUMO

Introduction: Introduction: Pellegrini-Stieda syndrome, characterized by medial collateral ligament (MCL) calcification or ossification, often follows a history of trauma. While rare, its distinct radiographic features pose diagnostic challenges. Conservative treatments are effective for many, but surgical intervention is necessary when they fail. Case Report: A 31-year-old male with knee pain and stiffness, an inability to extend his knee, and a fixed flexion deformity. Radiological examinations confirmed heterotopic ossification along the MCL, indicating post-traumatic Pellegrini-Stieda syndrome. Despite 3 months of conservative treatment, the patient's pain persisted, leading to surgical excision. The surgical approach involved diagnostic arthroscopy, revealing arthritic changes and adhesions. Arthroscopic adhesiolysis and open excision of the ossified mass significantly improved the patient's range of motion. Histopathological examination confirmed heterotopic bone formation. Follow-up appointments at 1, 3, and 6 months showed a pain-free and mobile knee joint, with the Pellegrini-Stieda lesion disappearing from radiographs. Conclusion: This case underscores the effectiveness of surgical intervention for refractory Pellegrini-Stieda syndrome, offering hope for improved patient outcomes and highlighting the importance of early diagnosis and tailored treatment in managing this rare condition.

16.
J Orthop Case Rep ; 14(2): 112-116, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38420228

RESUMO

Introduction: Osteomyelitis is one of the most common infectious complications in people with sickle cell disease (SCD). The most common infecting organisms in SCD are the Salmonella species and Staphylococcus aureus; Streptococcus pneumoniae and Bacteroides species have also been described, however, osteomyelitis attributable to infection with hypervirulent Klebsiella spp. is a rare entity. We describe our experience with a rare presentation of multifocal bilateral symmetrical ulna and fibula osteomyelitis in a patient with SCD due to Klebsiella bacteremia with 1-year follow-up. Case Report: A 25-year-old female known SCD since childhood who underwent treatment for dengue at our hospital had her blood cultures positive for Klebsiella, following which she was treated with appropriate antibiotics. Two weeks following the asymptomatic period patient presented with complaints of pain over the bilateral forearm and legs. The patient was evaluated for laboratory parameters and plain radiograph of the bilateral forearm and bilateral legs. The radiological features were suggestive of osteomyelitis, showing "Bilaterally symmetrical involvement." Laboratory parameters erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were found raised. The patient was planned for biopsy and debridement of the lesion from the right ulna. The culture from the biopsy showed growth of Klebsiella sp. and was sensitive to co-trimoxazole. The patient was started on co-trimoxazole for 6 weeks and had a significant clinical improvement in the form of subsidence of pain, normalization of the blood counts along with the acute phase reactants (ESR, CRP). Conclusion: Our case contributes to the growing awareness of the unusual manifestations of this serious disease and the rarity of bilateral symmetrical involvement. Our case highlights the importance of clinician awareness, manifestations, and management of Klebsiella sp. hypervirulent strains.

17.
Cureus ; 15(3): e35764, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37025731

RESUMO

INTRODUCTION: Plantar fasciitis is a debilitating clinical condition and is one of the most common causes of heel pain. The risk factors include frequent and prolonged running, obesity, a sedentary lifestyle, work-related weight bearing, and inappropriate footwear. Ultrasonography being a non-invasive, cost-effective, and easily available modality is a useful adjunct in the diagnosis. METHODS: A prospective observational study was conducted among 30 patients with unilateral plantar fasciitis. The diagnosis was based on history and examination. Heel pad thickness and plantar fascia thickness were recorded using ultrasonography. RESULTS: The ultrasonography results showed increased plantar fascia and heel pad thickness in the affected limb with plantar fasciitis than the normal one (p<0.001). The BMI was positively correlated with the heel pad thickness (p<0.05). The receiver operating characteristic (ROC) curve showed 90% sensitivity and 60% specificity for heel pad thickness (p<0.001). CONCLUSIONS: Ultrasonography is a sensitive and specific tool to identify patients with plantar fasciitis.

18.
J Orthop Case Rep ; 13(1): 87-91, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37143562

RESUMO

Introduction: Coracoid fracture occurs with shoulder instability due to direct humeral head impaction. Incidence coracoid fracture with shoulder dislocation is rare amounts to 0.8-2%. We encountered clinical challenge of unique combination of both shoulder instability and coracoid fracture. This technical note will describe the treatment of the same. Case Report: A 23-year-old male suffering from recurrent shoulder dislocation sustained coracoid fracture. Further evaluation showed glenoid defect of 25%. Magnetic resonance study showed on track lesion with Hill-Sach lesion of 9 mm, labral defect anteriorly with no associated rotator cuff tear. The patient was managed with open Latarjet procedure with fracture coracoid fragment with conjoint tendon as graft. Conclusion: Our purpose of reporting this technical note is to provide an option of dealing both instability and coracoid fracture in single sitting and usage of coracoid fractured fragment as an excellent graft of choice in acute presentation. However, certain limitations such as adequacy of graft in size and shape do exist operating surgeon which must be aware of the same.

19.
Angew Chem Int Ed Engl ; 48(25): 4602-4, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19444845

RESUMO

Quite sublime: Thin-layer fabrication of unsublimable large polycyclic aromatic hydrocarbons (PAHs) by pulsed laser deposition was used to prepare samples for scanning tunneling microscopy. Giant PAHs with up to 222 carbon atoms can be visualized-a size that was previously not possible because of the lack of suitable deposition methods.

20.
J Nanosci Nanotechnol ; 8(8): 4106-10, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19049184

RESUMO

ZnO nanotetrapods have been obtained in large quantities by carbothermal reduction of ZnO powder. These were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, UV-visible spectroscopy and photoluminescence. Electron microscopy revealed that the overall size of the tetrapods is 1.5-2 microm and legs are 30-50 nm in diameter. The size of tetrapods as well as diameter of the legs was found to increase with deposition temperature. Photoluminescence spectra revealed that green emission originating from oxygen vacancies overwhelmed that of the near-band-edge ultraviolet peak. A band gap of 3.27 eV was calculated from optical absorption spectra which agreed well with that estimated from PL spectra. Gas sensing properties of tetrapods were investigated and these were found to be 5 times more sensitive to H2S gas at room temperature in comparison to ZnO bulk polycrystalline material.

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