Hidden non-collinear spin-order induced topological surface states

Rare-earth monopnictides are a family of materials simultaneously displaying complex magnetism, strong electronic correlation, and topological band structure. The recently discovered emergent arc-like surface states in these materials have been attributed to the multi-wave-vector antiferromagnetic order, yet the direct experimental evidence has been elusive. Here we report observation of non-collinear antiferromagnetic order with multiple modulations using spin-polarized scanning tunneling microscopy. Moreover, we discover a hidden spin-rotation transition of single-to-multiple modulations 2 K below the Néel temperature. The hidden transition coincides with the onset of the surface states splitting observed by our angle-resolved photoemission spectroscopy measurements. Single modulation gives rise to a band inversion with induced topological surface states in a local momentum region while the full Brillouin zone carries trivial topological indices, and multiple modulation further splits the surface bands via non-collinear spin tilting, as revealed by our calculations. The direct evidence of the non-collinear spin order in NdSb not only clarifies the mechanism of the emergent topological surface states, but also opens up a new paradigm of control and manipulation of band topology with magnetism.

Interface-induced superconductivity in magnetic topological insulators

The interface between two different materials can show unexpected quantum phenomena. In this study, we used molecular beam epitaxy to synthesize heterostructures formed by stacking together two magnetic materials, a ferromagnetic topological insulator (TI) and an antiferromagnetic iron chalcogenide (FeTe). We observed emergent interface-induced superconductivity in these heterostructures and demonstrated the co-occurrence of superconductivity, ferromagnetism, and topological band structure in the magnetic TI layer-the three essential ingredients of chiral topological superconductivity (TSC). The unusual coexistence of ferromagnetism and superconductivity is accompanied by a high upper critical magnetic field that exceeds the Pauli paramagnetic limit for conventional superconductors at low temperatures. These magnetic TI/FeTe heterostructures with robust superconductivity and atomically sharp interfaces provide an ideal wafer-scale platform for the exploration of chiral TSC and Majorana physics.

Ordering of room-temperature magnetic skyrmions in a polar van der Waals magnet

Control and understanding of ensembles of skyrmions is important for realization of future technologies. In particular, the order-disorder transition associated with the 2D lattice of magnetic skyrmions can have significant implications for transport and other dynamic functionalities. To date, skyrmion ensembles have been primarily studied in bulk crystals, or as isolated skyrmions in thin film devices. Here, we investigate the condensation of the skyrmion phase at room temperature and zero field in a polar, van der Waals magnet. We demonstrate that we can engineer an ordered skyrmion crystal through structural confinement on the μm scale, showing control over this order-disorder transition on scales relevant for device applications.

Direct Visualization of Surface Spin-Flip Transition in MnBi_{4}Te_{7}

We report direct visualization of spin-flip transition of the surface layer in antiferromagnet MnBi_{4}Te_{7}, a natural superlattice of alternating MnBi_{2}Te_{4} and Bi_{2}Te_{3} layers, using cryogenic magnetic force microscopy (MFM). The observation of magnetic contrast across domain walls and step edges confirms that the antiferromagnetic order persists to the surface layers. The magnetic field dependence of the MFM images reveals that the surface magnetic layer undergoes a first-order spin-flip transition at a magnetic field that is lower than the bulk transition, in excellent agreement with a revised Mills model. Our analysis suggests no reduction of the order parameter in the surface magnetic layer, implying robust ferromagnetism in the single-layer limit. The direct visualization of surface spin-flip transition not only opens up exploration of surface metamagnetic transitions in layered antiferromagnets, but also provides experimental support for realizing quantized transport in ultrathin films of MnBi_{4}Te_{7} and other natural superlattice topological magnets.

Room-temperature skyrmion lattice in a layered magnet (Fe0.5Co0.5)5GeTe2

Novel magnetic ground states have been stabilized in two-dimensional (2D) magnets such as skyrmions, with the potential next-generation information technology. Here, we report the experimental observation of a Néel-type skyrmion lattice at room temperature in a single-phase, layered 2D magnet, specifically a 50% Co-doped Fe₅GeTe₂ (FCGT) system. The thickness-dependent magnetic domain size follows Kittel's law. The static spin textures and spin dynamics in FCGT nanoflakes were studied by Lorentz electron microscopy, variable-temperature magnetic force microscopy, micromagnetic simulations, and magnetotransport measurements. Current-induced skyrmion lattice motion was observed at room temperature, with a threshold current density, j_th = 1 × 10⁶ A/cm². This discovery of a skyrmion lattice at room temperature in a noncentrosymmetric material opens the way for layered device applications and provides an ideal platform for studies of topological and quantum effects in 2D.

Evaluation of a multiplex flow immunoassay versus conventional assays in detecting autoantibodies in systemic lupus erythematosus

INTRODUCTION

Conventional diagnostic assays are being replaced with automated multiplex assays, but their performance needs to be evaluated. We compared a multiplex flow immunoassay with conventional techniques in the detection of antinuclear antibodies (ANAs) and antibodies to specific extractable nuclear antigens (ENAs) in serum samples from patients with systemic lupus erythematosus.

METHODS

A total of 140 consecutive Chinese patients with systemic lupus erythematosus and 41 healthy controls were included. The automated BioPlex 2200 ANA Screen assay (Bio-Rad Laboratories, Hercules [CA], US) was compared with indirect immunofluorescence. In addition, use of BioPlex 2200 to detect anti-ENA antibodies was compared with in-house assays of countercurrent immunoelectrophoresis (CIEP), enzyme-linked immunosorbent assay (ELISA), and line blot.

RESULTS

The sensitivity and specificity of BioPlex in detecting ANAs (91.4% and 95.1%, respectively) were comparable to those of indirect immunofluorescence (90.7% and 85.4%, respectively). Overall, BioPlex achieved the best agreement with ELISA in detecting anti-ENA antibodies: agreement was >90% for most antibody types (κ=0.79-0.94). In contrast, agreement was poorest with CIEP, ranging from 85.6% (κ=0.33) for anti-Sm antibodies to 93.9% (κ=0.88) for anti-Ro antibodies. Overall, BioPlex and ELISA had the highest sensitivity, whereas CIEP had the highest specificity. In terms of disease association, anti-Sm detected by CIEP had the best positive predictive value and specificity for lupus nephritis.

CONCLUSIONS

In a local lupus cohort, BioPlex showed comparable sensitivity to indirect immunofluorescence in detecting ANAs and comparable performance to ELISA in detecting anti-ENA antibodies. However, CIEP was the best method in terms of disease specificity.

Kinetics and equilibrium adsorption study of selenium oxyanions onto Al/Si and Fe/Si coprecipitates

Inappropriate treatments for the effluents from semiconductor plants might cause the releases and wide distributions of selenium (Se) into the ecosystems. In this study, Al/Si and Fe/Si coprecipitates were selected as model adsorbents as they often formed during the wastewater coagulation process, and the removal efficiency of selenite (SeO₃) and selenate (SeO₄) onto the coprecipitates were systematically examined. The removal efficiency of SeO₃ and SeO₄ was highly related to surface properties of Al/Si and Fe/Si coprecipitates. The surface-attached Al shell of Al/Si coprecipitates shielded a portion of negative charges from the core SiO₂, resulting in a higher point of zero charge than that of Fe/Si coprecipitates. Thus, adsorption of SeO₃/SeO₄ was favorable on the Al/Si coprecipitates. Adsorptions of both SeO₃ and SeO₄ on Al/Si coprecipitates were exothermic reactions. On Fe/Si coprecipitates, while SeO₃ adsorption also showed the exothermic behavior, SeO₄ adsorption occurred as an endothermic reaction. The kinetic adsorption data of SeO₃/SeO₄ on Al/Si and Fe/Si coprecipitates were described well by the pseudo-second-order kinetic model. SeO₄ and SeO₃ adsorption on Fe/Si or Al/Si were greatly inhibited by the strong PO₄ ligand, whereas the weak ligand such as SO₄ only significantly affected SeO₄ adsorption. The weakest complex between SeO₄ and Al was implied by the essentially SeO₄ desorption as SeO₄/PO₄ molar ratios decreased from 0.5 to 0.2. These results were further confirmed by the less SeO₄ desorption (41%) from Fe/Si coprecipitates than that from Al/Si coprecipitates (78%) while PO₄ was added sequentially.

Comparison of Kaposi Sarcoma Risk in Human Immunodeficiency Virus-Positive Adults Across 5 Continents: A Multiregional Multicohort Study

BACKGROUND

We compared Kaposi sarcoma (KS) risk in adults who started antiretroviral therapy (ART) across the Asia-Pacific, South Africa, Europe, Latin, and North America.

METHODS

We included cohort data of human immunodeficiency virus (HIV)-positive adults who started ART after 1995 within the framework of 2 large collaborations of observational HIV cohorts. We present incidence rates and adjusted hazard ratios (aHRs).

RESULTS

We included 208140 patients from 57 countries. Over a period of 1066572 person-years, 2046 KS cases were diagnosed. KS incidence rates per 100000 person-years were 52 in the Asia-Pacific and ranged between 180 and 280 in the other regions. KS risk was 5 times higher in South African women (aHR, 4.56; 95% confidence intervals [CI], 2.73-7.62) than in their European counterparts, and 2 times higher in South African men (2.21; 1.34-3.63). In Europe, Latin, and North America KS risk was 6 times higher in men who have sex with men (aHR, 5.95; 95% CI, 5.09-6.96) than in women. Comparing patients with current CD4 cell counts ≥700 cells/µL with those whose counts were <50 cells/µL, the KS risk was halved in South Africa (aHR, 0.53; 95% CI, .17-1.63) but reduced by ≥95% in other regions.

CONCLUSIONS

Despite important ART-related declines in KS incidence, men and women in South Africa and men who have sex with men remain at increased KS risk, likely due to high human herpesvirus 8 coinfection rates. Early ART initiation and maintenance of high CD4 cell counts are essential to further reducing KS incidence worldwide, but additional measures might be needed, especially in Southern Africa.

Allergy in Hong Kong: an unmet need in service provision and training

Many children in Hong Kong have allergic diseases and epidemiological data support a rising trend. Only a minority of children will grow out of their allergic diseases, so the heavy clinical burden will persist into adulthood. In an otherwise high-quality health care landscape in Hong Kong, allergy services and training are a seriously unmet need. There is one allergy specialist for 1.5 million people, which is low not only compared with international figures, but also compared with most other specialties in Hong Kong. The ratio of paediatric and adult allergists per person is around 1:460 000 and 1:2.8 million, respectively, so there is a severe lack of adult allergists, while the paediatric allergists only spend a fraction of their time working with allergy. There are no allergists and no dedicated allergy services in adult medicine in public hospitals. Laboratory support for allergy and immunology is not comprehensive and there is only one laboratory in the public sector supervised by accredited immunologists. These findings clearly have profound implications for the profession and the community of Hong Kong and should be remedied without delay. Key recommendations are proposed that could help bridge the gaps, including the creation of two new pilot allergy centres in a hub-and-spoke model in the public sector. This could require recruitment of specialists from overseas to develop the process if there are no accredited allergy specialists in Hong Kong who could fulfil this role.

Social obstetrics: non-local expectant mothers admitted through accident and emergency department in a public hospital in Hong Kong

OBJECTIVES

To review the pregnancy outcomes of non-booked, non-local pregnant women delivering in Kwong Wah Hospital via admission to the Accident and Emergency Department 1 year after the announcement by the Hospital Authority to stop antenatal booking for non-eligible persons; and to perform a literature review of local studies about non-eligible person deliveries over the last decade.

DESIGN

Case series.

SETTING

A public hospital in Hong Kong.

PARTICIPANTS

All women who held the People's Republic of China passport or the two-way permit and those non-eligible persons whose spouses were Hong Kong Identity Card holders, who delivered in Kwong Wah Hospital from 1 April 2011 to 31 March 2012.

RESULTS

Overall, 219 women who were non-eligible persons delivered 221 live births during the study period. Compared with the annual statistics of Kwong Wah Hospital in 2011, non-local mothers were of higher parity; more likely to have hypertensive disease (including pre-eclamptic toxaemia), preterm deliveries (ie at <37 weeks), babies needing admission to the special care baby unit, and macrosomic babies (ie weighing >4.0 kg). The rates of induction of labour and caesarean section were lower in this group. There was no significant difference in the maternal and neonatal outcomes between women who had no booking and those who had a booking in another Hospital Authority or private hospital. There were many incidents of near-miss obstetric complications or suboptimally managed obstetric conditions due to lack of well-structured and continuous antenatal care in this group of non-eligible persons.

CONCLUSION

Non-eligible person delivering babies in Hong Kong has become a social obstetrics phenomenon. Despite the introduction of policies, reduction in the number of deliveries (quantity) did not improve the obstetric outcomes (quality). Health care professionals should continue to be prepared for managing the potential near-miss clinical complications in this group of 'travelling mothers'.

Ethyl acetate extract of Chinese medicinal herb Sarcandra glabra induces growth inhibition on human leukemic HL-60 cells, associated with cell cycle arrest and up-regulation of pro-apoptotic Bax/Bcl-2 ratio

Sarcandra glabra (Thunb.) Nakai, colloquially known as Caoshanhu, is a Chinese medicinal herb with reported anti-tumor, anti-inflammatory, anti-viral and non-specific immunoenhancing properties. Although the plant has been clinically used for treating a variety of diseases, its bioactive ingredients are largely unknown and its mode of action has never been investigated. In this study, the anti-tumor property of ethyl acetate (EA) extract of S. glabra was investigated by determining its in vitro growth-inhibitory effects on a panel of human cancer cell lines of different histotypes. Growth inhibition of the EA extract on the cancer cells seemed to be selective, and the leukemic HL-60 was found to be the most responsive after 48 h of treatment (IC50=58 microg/ml). Flow cytometric studies further illustrated that the extract might interfere with DNA replication and thus arrested the cell cycle at S phase in the leukemic cells, followed by DNA fragmentation and loss of phospholipid asymmetry in the plasma membrane after 72 h of treatment. Concurrently, the pro-apoptotic Bax/Bcl-2 ratio was also up-regulated by more than 178% of the control level. All these findings suggested that the extract had initiated apoptosis to kill the leukemic cells. Results from this pioneer study help to establish a scientific foundation for future research and development of the bioactive ingredients in EA extract of S. glabra as efficacious anti-cancer agents.

An easy method to reduce anterior shoulder dislocation: the Spaso technique

OBJECTIVE

To introduce the Spaso technique for reducing anterior shoulder dislocation by reporting the success rate of the Spaso technique performed by junior emergency medicine residents.

DESIGN

Retrospective case series.

SETTING

Urban accident and emergency department.

PARTICIPANTS

Patients with anterior shoulder dislocations.

INTERVENTIONS

The Spaso technique was applied by the emergency medicine residents to reduce anterior shoulder dislocation.

RESULTS

The emergency medicine residents applied the Spaso technique to reduce 16 cases of anterior dislocated shoulder during the study period. The Spaso technique was successful in 14 of 16 cases. The overall success rate was 87.5% (95% CI 60.4, 97.8%). No complications were noted.

CONCLUSION

A new method has been introduced for reduction of anterior shoulder dislocation by reporting the experience of junior residents. The Spaso technique is simple, effective and able to be performed by single operator. Although the sample size was small, the result of the study could provide background information for planning a properly designed randomised controlled trial to evaluate the Spaso technique.

Highly successful long-term outcome of kidney transplantation in Chinese recipients: an enhancing race effect?

We report on 352 cadaveric kidney transplants and 294 living related transplants performed over a 25-yr period among the Chinese population of Hong Kong. There is a marked preference for transplanting male patients, especially from living donors, and we argue that this represents a cultural phenomenon within the Chinese population. The 10-yr graft survivals for related and cadaveric transplants are 86.2% and 67.4%, respectively. These figures are appreciably higher than corresponding figures in Caucasian populations. We show beneficial effects of using cyclosporin A, minimizing the cold ischemia time and avoiding very young and very old donors. There is a clear benefit of transplanting kidneys with zero or one mismatched HLA antigen against the recipient but no stepwise decrease in outcome as the number of mismatched antigens increases. There is close concordance between the outcome of living related grafts with zero, one, and two mismatched haplotypes against the recipient and no observable benefit of haplotype matching. We show that Chinese renal transplant recipients in other centers also have better long-term graft outcome than Caucasians, both for cadaveric and living related transplants. We draw attention to the existence of a detrimental "race effect" in other studies when Black recipients are compared with Caucasians and consider whether an enhancing race effect exists for Chinese or whether the better outcome reflects different underlying diseases in Chinese.

Improved treatment outcome in adult acute lymphoblastic leukemia using the intensive German protocol, a preliminary report

Thirty-nine consecutive patients with acute lymphoblastic leukemia were treated with an intensive chemotherapy protocol. There were 23 males and 16 females with a median age of 37 years (range: 15-65). Eighteen patients had common ALL, seven had pre-B ALL, three early-precursor B ALL, seven T-ALL and four had aberrant expression of myeloid antigens (c-ALL in three and pre-B ALL in one). The median initial leukocyte count was 11.8 x 10(9)/l (range: 0.65-295). Cytogenetic result of the marrow was available in 16 of 39 patients (41 per cent) and showed Philadelphia positivity in six, a normal result in six and one each of t(4,11), t(1,19), hyperdiploidy and del 12p. Hepatosplenomegaly was present in about 20 per cent of the patients. L-Asparaginase-related hepatic toxicity was the commonest toxicity (48.7 per cent) during phase I of induction. Prolonged pancytopenia and hypoplastic death were common during phase II. With the use of growth factors during the neutropenic period of phase II induction, the rate of hypoplastic death was reduced from 40 per cent to 3 per cent. Common causes of treatment failure included early hypoplastic death (27.8 per cent) and leukemia relapses (50 per cent) while primary refractory leukemia, hepatic failure and perforated peptic ulcer contributed to 11.1, 5.5 and 5.5 per cent of the other deaths. A high complete remission (CR) rate (87.4 per cent) was achieved after phase I induction. The median event-free survival (EFS) was 8 months and the 3-year event-free survival was 43 per cent. This result compared favourably to the other regimens previously employed in our institution. In conclusion, satisfactory survival can be achieved with this intensive regimen. Good supportive care was however, essential to minimize toxicities.

A phase II study of single agent paclitaxel in patients at first relapse following initial chemotherapy for breast cancer

This study was initiated to evaluate the safety and efficacy of 3-weekly paclitaxel given at 225 mg/m2 over 3 hours without colony stimulating factor support in patients at their first relapse following adjuvant therapy for breast cancer. Thirty patients were entered into the study; all were assessable for response and toxicity. All patients had received adjuvant/neo-adjuvant chemotherapy; 22 patients had had prior hormonal therapy and 26 previous adjuvant radiotherapy. The group was characterized by a short time to first relapse (median 7.5 months (range 2-43)) and widespread disease, with 22 patients having multiple disease sites including: nodes (43%), skin and soft tissue (43%), liver (40%), lung (37%) and bone (50%). A total of 219 cycles of paclitaxel were given, with a median of eight per patient. The major non-haematological toxicities were: grade 3 alopecia (82% cycles), grade 2/3 arthralgia/myalgia (26%), grade 2/3 fatigue (16%) and grade 2/3 peripheral nervous system toxicity (12%). Haematological toxicity was mainly neutropenia of short duration, with grade 4 counts documented in 16% of cycles. Thrombocytopenia was minimal and there were no significant hypersensitivity reactions. The objective response rate was 60% (95% CI 42.5-77.5) with one complete response and 17 partial responses. The median duration of overall response was 30 weeks (range 15-75+ (95% CI 25-33)) with a median survival time for all patients of 42 weeks (range 1-124+). This study demonstrates that paclitaxel 225 mg/m2 is well tolerated as a 3-hour infusion and can be given safely in an outpatient setting without routine use of granulocyte colony stimulating factor. The response rate is encouraging and shows that this regimen is effective in this poor prognosis patient population.

Human lagochilascariasis treated successfully with ivermectin: a case report

A 15 year old male patient was diagnosed as being infected with the nematode Lagochilascaris minor, presenting as abscesses over the left mastoid region, and invading the temporal bone, mastoid sinuses and possibly the CNS. Surgical drainage and administration of cambendazole and levamisole led to improvement, followed by an early relapse and poor tolerance to the antihelminthic drugs. Repeated doses of ivermectin (an animal preparation) were used for the first time to treat this condition and resulted in complete remission of signs of infection, maintained for 15 months after the end of drug therapy, indicating cure of the disease.

Use of skin staples for fixation of T tubes and drains

Stapled anchorage is safe and effective for T tubes and drains and is preferred to the conventional technique. Significant bile leaks never occur. Three and two staples are recommended for anchoring T tubes and drains, respectively.

Endoscopic sphincterotomy in young patients with choledochal dilatation and a long common channel: a preliminary report

An anomalous elongated pancreaticobiliary common channel encourages reflux up both the biliary tree and the pancreatic ductal system, resulting in progressive choledochal dilatation, cholangitis with ductal calculi, relapsing pancreatitis and malignant change. Transduodenal sphincteroplasty has been used to improve drainage from the abnormal channel. The use of endoscopic sphincterotomy (ES) to establish drainage and minimize the surgical risks is reported in six symptomatic patients with mild choledochal dilatation (common bile duct diameter less than 15 mm), a common channel less than 15 mm in length and a distal stenosis. This was successful in five patients, who have no further symptoms. ES failed in the only patient with an undilated common channel and this patient went on to have open surgery. We believe ES to be safe and effective in the treatment of selected cases of long common channel.

Intestinal obstruction due to axial twisting of bowel in transmesenteric hernia

A baby, born with gastroschisis, had an unrepaired large aperture in the mesocolon close to a short segment of colon. One day, the entire length of bowel proximal to the defect traversed the rent. The free segment of colon was affected by the resulting twist along the long axis of the bowel and became obstructed. A large mesenteric defect, albeit too wide to strangulate the bowel, is not totally innocuous and should always be closed.

Presacral myelolipoma: case report with computed tomographic and angiographic findings

A rare case of presacral myelolipoma in an otherwise healthy 53 year old man is described. His only complaint was lower abdominal discomfort. Full investigation including computed tomography and angiography revealed a well-delineated, heavily calcified, avascular retrorectal mass adhering to the presacral fascia. Histologically the mass showed a mixture of haemopoietic tissue and mature fat cells. Clinically the absence of symptoms and bone involvement served to distinguish this condition from other more sinister presacral lesions, particularly a chordoma.

Recurrent pancreatitis contributing to choledochal cyst formation

We report three cases of choledochal cyst. The calibre of the common bile duct in each of them was demonstrated by ultrasonogram, CT scan, radiography and laparotomy to be almost normal before recurrent attacks of pancreatitis, following which the common bile duct was shown to become grossly dilated. This observation leads us to surmise that recurrent pancreatitis contributes to the formation of choledochal cysts.

Polyps and diverticula of the large intestine: a necropsy survey in Hong Kong

The study is based on a prospective survey of 200 necropsies, to determine the prevalence of colonic polyps and diverticula in Hong Kong. Adenomatous polyps were found in 34% of men and 19% of women. The corresponding figures for hyperplastic polyps were 22% and 15%. When compared with European countries having similar rates for colorectal cancer, the polyp pattern by type, prevalence, and distribution is very similar. For diverticula the prevalence rate in this study was only 5%; most of these were situated in the caecum. This is at marked variance to the European pattern.

Primary leiomyosarcoma of renal capsule

The renal capsule long has been suggested to be the origin of leiomyosarcoma of the kidney but this speculation has never been proved. We describe a case of leiomyosarcoma lying with the renal capsule. The radiographic, as well as the macroscopic and microscopic appearances provide convincing evidence of capsular origin.

Pan-caliceal ileoneocystostomy--a new operation for intrapelvic tuberculotic strictures of the renal pelvis

Intrarenal scarring with stricture formation is common in late cases of renal tuberculosis and has caused more loss of renal function than direct involvement by tuberculosis. The classical treatment of this condition is heminephrectomy for early cases and total nephrectomy for late cases. However, these destructive procedures are far from satisfactory. We describe a new operation, pan-caliceal ileoneocystostomy, that aims at draining the entire caliceal system into an ileal ureter, which thereby relieves the obstruction. Good results were obtained in 2 cases. This procedure also is applicable to cases of intrarenal scarring with stricture formation owing to other causes.