Crystal bending in triple-Laue X-ray interferometry. Part II. Phase-contrast topography

In a previous paper [Sasso et al. (2023). J. Appl. Cryst. 56, 707-715], the operation of a triple-Laue X-ray interferometer having the splitting or recombining crystal cylindrically bent was studied. It was predicted that the phase-contrast topography of the interferometer detects the displacement field of the inner crystal surfaces. Therefore, opposite bendings result in the observation of opposite (compressive or tensile) strains. This paper reports on the experimental confirmation of this prediction, where opposite bendings were obtained by copper deposition on one or the other of the crystal sides

Crystal bending in triple-Laue X-ray interferometry. Part I. Theory

The measured value of the (220) lattice-plane spacing of silicon 28 using scanning X-ray interferometry is essential to realize the kilogram by counting Si-28 atoms. An assumption made is that the measured lattice spacing is the bulk value of an unstrained crystal forming the analyser of the interferometer. However, analytical and numerical studies of the X-ray propagation in bent crystals suggest that the measured lattice spacing might refer to the analyser surface. To confirm the result of these studies and to support experimental investigations of the matter by phase-contrast topography, a comprehensive analytical model is given of the operation of a triple-Laue interferometer having the splitting or recombining crystal bent

Amifostine reduces the seminiferous epithelium damage in doxorubicin-treated prepubertal rats without improving the fertility status

<p>Abstract</p> <p>Background</p> <p>Amifostine is an efficient cytoprotector against toxicity caused by some chemotherapeutic drugs. Doxorubicin, a potent anticancer anthracycline, is known to produce spermatogenic damage even in low doses. Although some studies have suggested that amifostine does not confer protection to doxorubicin-induced testicular damage, schedules and age of treatment have different approach depending on the protocol. Thus, we proposed to investigate the potential cytoprotective action of amifostine against the damage provoked by doxorubicin to prepubertal rat testes (30-day-old) by assessing some macro and microscopic morphometric parameters 15, 30 and 60 days after the treatment; for fertility evaluation, quantitative analyses of sperm parameters and reproductive competence in the adult phase were also carried out.</p> <p>Methods</p> <p>Thirty-day-old male rats were distributed into four groups: Doxorubicin (5 mg/kg), Amifostine (400 mg/kg), Amifostine/Doxorubicin (amifostine 15 minutes before doxorubicin) and Sham Control (0.9% saline solution). "Standard One Way Anova" parametric and "Anova on Ranks" non-parametric tests were applied according to the behavior of the obtained data; significant differences were considered when p < 0.05.</p> <p>Results</p> <p>The rats killed 30 and 60 days after doxorubicin treatment showed diminution of seminiferous epithelium height and reduction on the frequency of tubular sections containing at least one type of differentiated spermatogonia; reduction of sperm concentration and motility and an increase of sperm anomalous forms where observed in doxorubicin-treated animals. All these parameters were improved in the Amifostine/Doxorubicin group only when compared to Doxorubicin group. Such reduction, however, still remained below the values obtained from the Sham Control group. Nevertheless, the reproductive competence of doxorubicin-treated rats was not improved by amifostine pre-administration.</p> <p>Conclusions</p> <p>These results suggest that amifostine promotes a significant reduction of the doxorubicin long-term side effects on the seminiferous epithelium of prepubertal rats, which is reflected in the epidydimal fluid parameters in the adult phase. However, fertility status results suggest that such protection may not be effective against sperm DNA content damage. Further investigation of sperm DNA integrity must be carried out using amifostine and doxorubicin-treated experimental models.</p

Canagliflozin and Cardiovascular and Renal Outcomes in Type 2 Diabetes Mellitus and Chronic Kidney Disease in Primary and Secondary Cardiovascular Prevention Groups

Background: Canagliflozin reduces the risk of kidney failure in patients with type 2 diabetes mellitus and chronic kidney disease, but effects on specific cardiovascular outcomes are uncertain, as are effects in people without previous cardiovascular disease (primary prevention). Methods: In CREDENCE (Canagliflozin and Renal Events in Diabetes With Established Nephropathy Clinical Evaluation), 4401 participants with type 2 diabetes mellitus and chronic kidney disease were randomly assigned to canagliflozin or placebo on a background of optimized standard of care. Results: Primary prevention participants (n=2181, 49.6%) were younger (61 versus 65 years), were more often female (37% versus 31%), and had shorter duration of diabetes mellitus (15 years versus 16 years) compared with secondary prevention participants (n=2220, 50.4%). Canagliflozin reduced the risk of major cardiovascular events overall (hazard ratio [HR], 0.80 [95% CI, 0.67-0.95]; P=0.01), with consistent reductions in both the primary (HR, 0.68 [95% CI, 0.49-0.94]) and secondary (HR, 0.85 [95% CI, 0.69-1.06]) prevention groups (P for interaction=0.25). Effects were also similar for the components of the composite including cardiovascular death (HR, 0.78 [95% CI, 0.61-1.00]), nonfatal myocardial infarction (HR, 0.81 [95% CI, 0.59-1.10]), and nonfatal stroke (HR, 0.80 [95% CI, 0.56-1.15]). The risk of the primary composite renal outcome and the composite of cardiovascular death or hospitalization for heart failure were also consistently reduced in both the primary and secondary prevention groups (P for interaction &gt;0.5 for each outcome). Conclusions: Canagliflozin significantly reduced major cardiovascular events and kidney failure in patients with type 2 diabetes mellitus and chronic kidney disease, including in participants who did not have previous cardiovascular disease

Canagliflozin and Renal Outcomes in Type 2 Diabetes and Nephropathy

BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodium–glucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to 300 to 5000) and were treated with renin–angiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of <15 ml per minute per 1.73 m 2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P<0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years

The watt-balance operation: magnetic force and induced electric potential on a conductor in a magnetic field

In a watt-balance experiment, separate measurements of magnetic force and induced electric potential in a conductor in a magnetic field allow for a virtual comparison between mechanical and electrical powers, which leads to an accurate measurement of the Planck constant. In this paper, the macroscopic equations for the magnetic force and the induced electric potential are re-examined from a microscopic point of view and the corrective terms due to a non-uniform density of the conduction electrons induced by their interaction with the magnetic field are investigated. The results indicate that these corrections are irrelevant to the watt-balance operation

Measurement of Individual Bond Magnetostrictive Strain in α-TbFe2

The structural changes exhibited by materials in response to their surroundings is of fundamental importance across countless disciplines in science and engineering. In the field of transducer technologies, strain-inducing phenomena (such as magnetostriction) are utilised in their own right, and form the physical foundation for sensor and actuator devices. Knowledge of their origin, and how they manifest themselves in different materials, underpins the development of new transducers and the optimisation of existing technologies. Yet in spite of this, direct measurement of a material’s intrinsic magnetostriction – the strain induced between individual atoms at a microscopic level – has proven elusive. This has essentially been due to the difficulty in measuring atomic motion with sufficient precision. In most materials, magnetostrictive atomic displacements saturate at just a few femtometres. Here, even sensitive atomic probes, such as x-ray absorption spectroscopy (XAS), lack the resolution to observe this motion by some two orders of magnitude. As a result, common experiments employ strain gauges on macroscopic samples, where the strain is easier to detect, but where atomic information is lost. However, with the recent development of differential XAS (DiffXAS) at the European Synchrotron Radiation Facility (ESRF), such atomic-scale measurements have become possible [1,2]. Initial studies into the magnetostriction of FeCo thin films demonstrated a sensitivity to femtometre scale motion [1]. Subsequent work extended this study to investigate the magnetoelastic coupling of FeCo under applied hydrostatic pressure [3], and new experiments looked into the behaviour of FePt, and rare-earth iron alloys such as Fe2Tb. But the most significant study conducted to date has been that of the Fe-Ga system [4,5]. In recent years, binary metal alloys such as Fe-Al or Fe-Ga, have attracted considerable interest [6]. It is well known that pure Fe exhibits only an extremely small magnetostriction, but when alloyed with certain nonmagnetic metallic elements, it can be enhanced by over an order of magnitude. Compositions of Fe-Ga with around 19at% Ga have reported strains of up to 400 ppm [7]. Although this doesn’t constitute a truly ‘giant’ magnetostriction, it is of interest for device applications since Fe-Ga is devoid of expensive rare-earth components, saturates in fields of only several hundred Oersteds, and possesses more desirable mechanical properties than, say, the much studied Terfenol-D alloy. In order to identify the origin of this enhancement, we took a splat-cooled foil of Fe81Ga19 and measured its Joule saturation magnetostriction with DiffXAS [4]. Unlike conventional macroscopic measurements that describe the sample as a whole, magnetostriction coefficients provided by DiffXAS describe the strain of just the first two or three atomic coordination shells surrounding a photo-excited atom. Furthermore, since it is possible to tune the x-ray energy, and so select which atom in the material is excited, it is possible to look at the strain in the local environment of each atomic species separately. Contributions from different types of bond within the structure may then be decoupled and analysed. Such fundamental information has immense value when attempting to verify theoretical models. In 2002, Wu [8] proposed a model for the magnetostriction of FexGa(1-x) that suggested a tetragonal “B2-like” structure in the vicinity of the Ga atoms was responsible for the observed enhancement. More recently, Cullen et al. [9] reached a similar conclusion, and stated that such a structure could be formed by Ga pairs randomly arranged throughout the material. Conventional XAS studies have confirmed the presence of these Ga pairs [5], but it is DiffXAS that describes how they influence the magnetostriction. From our DiffXAS spectra, we extracted the strain present in different types of bond, and with a subsequent analysis, solved the magnetostriction tensor for the material. This provided two sets of magnetostriction coefficients. In the environment around Fe, (3/2)100 = 40ppm and (3/2)111 = -32ppm, and in the environment around Ga, (3/2)100 = 390ppm and (3/2)111 ~0ppm. This demonstrates that the observed enhancement is dominated by strain in the vicinity of the Ga atoms. Furthermore, our analysis revealed that the strain in the Ga pairs was negligible, indicating that they do not contribute directly to the enhanced magnetostriction, but rather mediate the enhancement in the surrounding Ga-Fe bonds. Further experiments are planned to examine the full range of compositions over which magnetostriction enhancement is observed in this system, and, with the use of single crystal samples, investigate how the microscopic magnetostriction scales up to that seen macroscopically. [1] R.F. Pettifer, O. Mathon, S. Pascarelli, M.D. Cooke, M.R. J. Gibbs, Nature 435, 79 (2005) [2] M. P. Ruffoni, R.F. Pettifer, S. Pascarelli et al., AIP Conf. Proc. No. 882, 838 (2007) [3] S. Pascarelli, M. P. Ruffoni, A. Trapananti et al., Phys. Rev. Lett. 99, 237204 (2007) [4] M. P. Ruffoni, S. Pascarelli, R. Grössinger et al., Phys. Rev. Lett. 101, 147202 (2008) [5] S. Pascarelli, M. P. Ruffoni, R. Sato-Turtelli et al., Phys. Rev. B 77, 184406 (2008) [6] E. M. Summers, T. A. Lograsso, M. Wun-Fogle, J. Mater. Sci. 42, 9582 (2007) [7] A. E. Clark, A. B. Hathaway, M. Wun-Fogle et al., J. Appl. Phys. 93, 8621 (2003) [8] R. Wu, J. Appl. Phys. 91, 7358 (2002) [9] J. Cullen, P. Zhao, M. Wuttig, J. Appl. Phys. 101, 123922 (2007)Submitted versio

Transforaminal lumbar interbody fusion using unilateral pedicle screws and a translaminar screw

Lumbar spinal fusion is advancing with minimally invasive techniques, bone graft alternatives, and new implants. This has resulted in significant reductions of operative time, duration of hospitalization, and higher success in fusion rates. However, costs have increased as many new technologies are expensive. This study was carried out to investigate the clinical outcomes and fusion rates of a low implant load construct of unilateral pedicle screws and a translaminar screw in transforaminal lumbar interbody fusion (TLIF) which reduced the cost of the posterior implants by almost 50%. Nineteen consecutive patients who underwent single level TLIF with this construct were included in the study. Sixteen patients had a TLIF allograft interbody spacer placed, while in three a polyetheretherketone (PEEK) cage was used. Follow-up ranged from 15 to 54 months with a mean of 32 months. A clinical and radiographic evaluation was carried out preoperatively and at multiple time points following surgery. An overall improvement in Oswestry scores and visual analogue scales for leg and back pain (VAS) was observed. Three patients underwent revision surgery due to recurrence of back pain. All patients showed radiographic evidence of fusion from 9 to 26 months (mean 19) following surgery. This study suggests that unilateral pedicle screws and a contralateral translaminar screw are a cheaper and viable option for single level lumbar fusion

Acesso anterior para pacientes com fraturas traumáticas do tipo compressão do segmento toracolombar (T11 a L2) da coluna vertebral Anterior approach in patients with traumatic compression fracture type of thoracolumbar spine (T11-L2)

OBJETIVO: Relatar a experiência com o acesso anterior em fraturas traumáticas do tipo compressão no segmento toracolombar (T11 a L2) que foram submetidos à cirurgia pelo acesso anterior. MÉTODO: Estudo prospectivo de janeiro de 1994 a janeiro de 2004 envolvendo 32 pacientes. A presença da fusão óssea e do alinhamento foram analisadas 6 e 12 meses após a cirurgia. RESULTADOS: A idade média foi 36,53 anos, sendo 23 do sexo masculino. A vértebra mais atingida foi L1 (n=12). A maioria dos casos que internaram em ASIA/IMSOP C (n=10) e D (n=13) evoluiram para ASIA/IMSOP E. A média da deformidade angular pré-operatória foi 14,9&deg;&plusmn;7,5&deg;, com diferença estatística (p<0,0001) na comparação com o valor encontrado no pós-operatório de 30 dias. CONCLUSÃO: A via anterior permite melhor descompressão do canal e uma correção da deformidade angular superior à observada pela via posterior isolada.<br>OBJECTIVE: To describe experience with anterior access in compression fractures of thoracolumbar segment (T11 to L2) traumatic fractures that undergone anterior access surgery. METHOD: A prospective study was conducted between January 1994 and January 2004 with 32 patients. The bone fusion and thoracolumbar alignment were analyzed 6 months and 12 months after the surgery. RESULTS:The average age was 36.53 years old with 23 male patients. The most compromised vertebrae was L1 (n=12). The 23 patients that was ASIA/IMSOP C and ASIA/IMSOP D turned to ASIA/IMSOP E after 1 month (n=12) and 12 months (n=5) of surgery. The preoperative angular deformity average was 14.9&deg;&plusmn;7.5&deg;. Statistical significance was found (p<0.0001) when compared to the 30 days postoperative value. CONCLUSION: The anterior access permits a better spinal canal decompression and angular deformity correction when compared with the posterior access alone