Erbium-YAG and holmium-YAG laser ablation of bone

Results are presented for the latent heat of ablation of bone using an erbium-YAG laser operating at 2.9m, and a holmium-YAG laser operating at 2.1m. The values are 8.2±1.0 kJ cm^–3 and 18±2.0 kJ cm^–3, respectively. Secondary damage to surrounding tissue is found to extend approximately 5m with the erbium laser and is greatly increased to 80m with significant charring in the case of holmium. These secondary damage zones are much smaller than those produced by the CO₂ laser.     

A breast pre-cancer test? Preliminary results based on a breast temperature rhythm abnormality during the menstrual cycle

Summary This study documents the menstrual thermal cycle of 16 breasts considered at normal risk for breast cancer (8 women) and 15 breasts considered at high risk for breast cancer (i.e. ipsilateral N = 7 or contralateral N = 8 to a previously [locally] excised carcinoma). The surface thermometry studies were carried out for 1 1/2 hours each evening for one menstrual cycle using a special automated instrumentation, the Chronobra, with the subject at home. The surface temperatures were adjusted to remove the fluctuations in arterial blood temperature during the menstrual cycle, so that they are thought to represent a breast-specific menstrual rhythm. Across subjects, the cycles were synchronised by the day of the progesterone peak obtained by radioimmunoassay of saliva collected daily. Following ovulation, the normal risk breasts exhibited a steady rise of temperature for 14 days to a well defined peak. In contrast the high-risk breasts exhibited a continuous hyperthermia with smaller peaks. Linear discrimination analysis by multiple regression achieved a complete separation of the individual normal and high-risk data sets. The method shows promise for the development of a non-invasive screening test for breast pre-cancer in premenopausal women.     

主动脉瘤25例的影像诊断

目的探讨螺旋CT(SCT)和MRI对主动脉瘤的诊断价值。方法25例主动脉瘤,13例行MRI检查,12例行SCT及三维重建技术检查。三维重建方法采用表面阴影显示法(SSD)、最大密度投影(MaxIP)及多层面重建法(MPVR)。结果13例主动脉夹层MRI和SCT均较好显示主动脉夹层内膜片和真假腔,SCT显示内膜破口5例,MRI无一例显示;SCT及三维重建较好地显示了主动脉夹层的内膜撕裂的范围、真性主动脉瘤(TAA)瘤壁的厚度及钙化、附壁血栓的情况及与邻近大血管分支的关系。结论SCT及三维重建技术的联合应用较低场MRI更能明确主动脉瘤的病变,对帮助和指导手术更具有价值。     

甲基酚烯酸酯树脂的热裂解机理

研究了以甲基丙烯酸酯端基不饱和取酯树脂为主链,用甲基丙烯酸甲酯取代苯乙烯作为交联剂制成的甲基丙烯酸酯树脂（ＭＡＥＲ）与通用型不饱和聚酯树脂（ＧＵＰＲ）的热裂解机理、燃烧现象。结果表明：ＭＡＥＲ的裂角产物中苯环化合物含量（１４．９％）少于ＧＵＰＲ（７４．５％）。ＭＡＥＲ燃烧时的发烟量和毒性也远低于ＧＵＰＲ。在ＭＡＥＲ中加入三水合氧化铝（ＡＴＨ）后,裂解产物中有毒物质的各类和数量更少,在燃烧时只有少量     

图形设计中的写意造型

中国画的写意造型 ,展示的是似与不似之间、寓意于象、以象尽意“心物统一”的意象。在图形设计中采用写意造型方法 ,能使设计意念的表达更显符号化与象征性 ,同时也丰富观者感受层面与审美经验。     

红外线短波紫外线照射对感染伤口愈合的影响

目的：探讨红外线、短波紫外线照射对感染性伤口愈合的影响。方法：用随机方法将７２例感染伤口病人分为Ａ、Ｂ两组,每组３６例,Ａ为治疗组：在消炎、伤口换药基础上加用红外线、短波紫外线照射伤口７天,Ｂ为对照组：单纯消炎、伤口换药。结果：Ａ组治愈２８例,显效８例,有效率１００％。Ｂ组治愈１４例,显效１２例,无效１０例,有效率７２％,统计学处理Ｘ＾２＝１５．４７Ｐ〈０．０１,两组有显著差异。结论：红外线、短波     

Assessment of Photoinduced Frontal Polymerization Processes for a Stable 1K System

Frontal polymerization (FP) has attracted increasing interest in recent years in various applications. This polymerization method can be very promising for the polymerization of thick materials with high fillers content in the range of 50–80% (weight) by local application of a reasonable amount of energy. In this work, recent advances in controllable and predictive behavior for photoinduced frontal photopolymerization are reported. Here, tert-butyl peroxybenzoate (Luperox-P) is selected to initiate thermal polymerization at depth because its high polymerization ability and its decomposition temperature is in a promising range, i.e., neither extremely high (monomer decomposition) nor very low (storage stability issues). Thermal imaging experiments are used to follow the temperatures in the samples in real time. The number of cured layers and the depth of cure are also determined. This paper investigates various factors such as the contents of both photo and thermal initiators, the light intensity, the fiber contents, the irradiation time, etc., resulting in a statistical design of experiments with the factors: 1) content of Luperox P and 2) the irradiation time used to investigate the influence on photoinduced frontal polymerization. Markedly, FP appears to be fully controllable for a storage-stable, tunable 1K system.     

Gabapentin (neurontin) and S-(+)-3-isobutylgaba represent a novel class of selective antihyperalgesic agents

1. Gabapentin (neurontin) is a novel antiepileptic agent that binds to the α₂δ subunit of voltage-dependent calcium channels. The only other compound known to possess affinity for this recognition site is the (S)-(+)-enantiomer of 3-isobutylgaba. However, the corresponding (R)-(−)-enantiomer is 10 fold weaker. The present study evaluates the activity of gabapentin and the two enantiomers of 3-isobutylgaba in formalin and carrageenan-induced inflammatory pain models.
2. In the rat formalin test, S-(+)-3-isobutylgaba (1–100 mg kg⁻¹) and gabapentin (10–300 mg kg⁻¹) dose-dependently inhibited the late phase of the nociceptive response with respective minimum effective doses (MED) of 10 and 30 mg kg⁻¹, s.c. This antihyperalgesic action of gabapentin was insensitive to naloxone (0.1–10.0 mg kg⁻¹, s.c.). In contrast, the R-(−)-enantiomer of 3-isobutylgaba (1–100 mg kg⁻¹) produced a modest inhibition of the late phase at the highest dose of 100 mg kg⁻¹. However, none of the compounds showed any effect during the early phase of the response.
3. The s.c. administration of either S-(+)-3-isobutylgaba (1–30 mg kg⁻¹) or gabapentin (10–100 mg kg⁻¹), after the development of peak carrageenan-induced thermal hyperalgesia, dose-dependently antagonized the maintenance of this response with MED of 3 and 30 mg kg⁻¹, respectively. Similar administration of the two compounds also blocked maintenance of carrageenan-induced mechanical hyperalgesia with MED of 3 and 10 mg kg⁻¹, respectively. In contrast, R-(−)-3-isobutylgaba failed to show any effect in the two hyperalgesia models.
4. The intrathecal administration of gabapentin dose-dependently (1–100 μg/animal) blocked carrageenan-induced mechanical hyperalgesia. In contrast, administration of similar doses of gabapentin into the inflamed paw was ineffective at blocking this response.
5. Unlike morphine, the repeated administration of gabapentin (100 mg kg⁻¹ at start and culminating to 400 mg kg⁻¹) over 6 days did not lead to the induction of tolerance to its antihyperalgesic action in the formalin test. Furthermore, the morphine tolerance did not cross generalize to gabapentin. The s.c. administration of gabapentin (10–300 mg kg⁻¹), R-(−) (3–100 mg kg⁻¹) or S-(+)-3-isobutylgaba (3–100 mg kg⁻¹) failed to inhibit gastrointestinal motility, as measured by the charcoal meal test in the rat. Moreover, the three compounds (1–100 mg kg⁻¹, s.c.) did not generalize to the morphine discriminative stimulus. Gabapentin (30–300 mg kg⁻¹) and S-(+)-isobutylgaba (1–100 mg kg⁻¹) showed sedative/ataxic properties only at the highest dose tested in the rota-rod apparatus.
6. Gabapentin (30–300 mg kg⁻¹, s.c.) failed to show an antinociceptive action in transient pain models. It is concluded that gabapentin represents a novel class of antihyperalgesic agents.

     

Measurement of Glass Transition Temperatures of Freeze-Concentrated Solutes by Differential Scanning Calorimetry

Thermal analysis of aqueous solutions in which the solute does not crystallize immediately upon freezing was carried out to define the effects of experimental parameters on thermograms in the glass transition region. The intensity of enthalpy relaxations in the glass transition region is related to both the rate of cooling and the rate of heating through the glass transition region—slow cooling or slow heating increases the extent of structural relaxation in the glassy state and increases the intensity of the endotherm. Plots of the logarithm of heating rate versus l /Tg are linear, and activation enthalpies for structural relaxation are in the range of 210–350 kJ/mol. For polymeric solutes, both the activation enthalpies for structural relaxation and the heat capacity change accompanying the glass transition increase with increasing molecular weight of the solute. Molecular weight dependence of the observed midpoint of the glass transition agrees with the Fox–Flory relationship. Results are compared and contrasted with glass transitions in solid polymers and with the glass transition of hyperquenched water. Practical implications for characterization of formulations intended for freeze-drying are discussed.     

Periventricular- intraventricular hemorrhage in the premature infant- A historical perspective

The objective of this chapter is to trace the evolution of intraventricular hemorrhage in the premature infant highlighting the importance of the germinal matrix, a critical role for cerebral blood flow changes in the genesis of hemorrhage, clinical factors that increase the bleeding risk, and potential preventative strategies. In 1976, neuropathological studies demonstrated capillary rupture within the germinal matrix as the precursor of hemorrhage. In 1980, introduction of cranial ultrasound facilitated diagnosis of intraventricular hemorrhage. In 1979, loss of cerebral autoregulation in sick newborn infants was demonstrated. In the 1980’s, studies demonstrated the importance of intravascular factors in provoking hemorrhage. In 1983, the association of cerebral blood flow velocity fluctuations and subsequent hemorrhage was demonstrated. In 1994, antenatal steroids use to accelerate lung development was recommended. This was associated with an unanticipated reduction in hemorrhage. In the mid 1990’s early indomethacin administration was associated with a reduction of severe hemorrhage.